WO2007024505A2

WO2007024505A2 - Synthesized hybrid rock composition, method, and article formed by the method

Info

Publication number: WO2007024505A2
Application number: PCT/US2006/031324
Authority: WO
Inventors: Ross Guenther; James L. Wood; Carl E. Frahme; Ian I. Chang; Robert D. Villwock
Original assignee: Ceramext, Llc
Priority date: 2005-08-25
Filing date: 2006-08-09
Publication date: 2007-03-01
Also published as: CN103288354A; MX2008002511A; AU2006283780B2; ZA200801850B; WO2007024505A3; BRPI0614705A2; CN101228096A; AU2006283780A1; US20070049487A1; US20120235320A1; US20100273630A1; CN101228096B; CA2611749A1; WO2007024505A8; EP1917220A2; CA2611749C; US8216955B2; EP1917220A4; US8901023B2; US7704907B2

Abstract

The invention relates to synthetic hybrid rock compositions, articles of manufacture and related processes employing mineral waste starting materials such as mine tailings, mine development rock, ash, slag, quarry fines, and slimes, to produce valuable articles of manufacture and products, which are characterized by superior physical and structural characteristics, including low porosity, low absorption, increased strength and durability, and retained plasticity. The resulting materials are compositionally and chemically distinct from conventional synthetic rock materials as demonstrated by scanning electron microprobe analysis, and are useful in a wide variety of applications, particularly with respect to commercial and residential construction.

Description

Synthesized Hybrid Rock Composition., Method, and Article

Formed by the Method

Ross Guenther, James L. Wood, Carl E. Frahme, Ian I. Chang, and Robert D. Villwock

FIELD OF THE INVENTION

The following invention is generally directed to synthetic hybrid rock

compositions of matter, articles of manufacture and related processes employing as

starting material mine tailings, mine development rock, ash, slag, quarry fines, slimes,

and similar mineral waste materials.

DESCRIPTION OF RELATED ART

Mine reclamation and waste mineral processing are not, by far, new industries.

Numerous systems, processes and methods exist to affect environmental mine clean-up,

and manufacture useful products from raw materials comprised primarily of waste

minerals constituents.

U.S. Patent No. 3,870,535 discloses a method of treating coal mining refuse to

produce a cementitious material, which is self-hardening at atmospheric pressure, and

may be used as structural fill, road base material, or alternatively as an aggregate

consolidated barrier to prevent penetrating percolation and resulting surface water

contamination. The method involves treating coal mining tailings from coal extraction

processes with lime (to neutralize sulfuric acid), or lime and a pozzolanic material, such

as fly ash, to react at atmospheric pressure for at least several days, in the presence of

moisture with sulfate ions that have been released from the tailings, and in some cases

also to react with soluble iron products in the tailings. The claimed products are

admixtures of coal mining refuse and stoichiometrically distinct concentrations of lime,

water and fly ash. The products of the invention are generally of the variety 3CaO,

A1₂O3, 3CaSO₄, 30-32H₂O or 3CaO, Al₂O₃, CaSO₄, and 10-12H₂O. Permeability testing

data for product samples indicated that permeability diminished after completion of a

seven day curing period at 100° F. Likewise, compressive strength data indicated that the

material's compressive strength, measured in PSI, increased as the curing period

progressed. Detailed information regarding the composition's density and plasticity is

not disclosed. However, the composition is cementitious in nature, and therefore limited in application and potential utility. Well known disadvantages associated with cement

based products include high porosity and structural instability as a result of temperature

and climate fluctuations.

U.S. Patent No. 5,286,427 discloses a method of effecting environmental cleanup

by producing structural building materials using mine tailings waste material. The

method involves providing facilities for producing the structural building material;

providing raw materials for producing the building material, the raw materials comprising

unprocessed mine tailings (with a material gradation suitable for immediate use) as a

substitute for processed silica sand, plus cement and aluminum powder; analyzing the

mine tailings to determine composition and weight percentage amounts of other raw

materials present; preparing a slurry from the mine tailings and combining the slurry with

other raw materials to form a batch slurry; adjusting amounts of other raw materials in

accordance with determined weight percentage amounts in the mine tailings; and

processing the batch slurry through the provided facility, including a final curing step that

produces the building structural material. Due to the chemical reaction that takes place in

the casting stage, the production slurry changes from a fluid form to a quasi-solid form of

the building material. The quasi-solid form expands and conforms to a mold shape and

facilitates being cut into smaller units prior to curing. The autoclaved aerated cement, as

produced and claimed, is of limited utility because the composition lacks plasticity and is

therefore incapable of efficient subsequent reformation. Information regarding the

material's permeability, porosity, and required curing time period are not disclosed. As previously stated, well known disadvantages associated with cement include high

porosity and structural instability as a result of temperature and climate fluctuations.

U.S. Patent No. 6,825,139 discloses a crystalline composition, a poly-crystalline

product, an article of manufacture, and a related process utilizing coal ash as starting

material. The process involves mixing coal ash particles with at least one glass forming

agent and at least one crystallization catalyst, melting this combination to form a mixture,

and cooling the resulting mixture to ambient temperature to form a homogenous, non-

porous poly-crystalline product comprising SiO₂, Al₂O, CaO, Fe₂O₃, TiO₂, MgO, Na₂O,

Li₂O, CeO₂, ZrO₂, K₂O₅ P₂O₅, Cr₂O₃, ZnO and MnO₂. The poly-crystalline products are

poly-crystalline materials obtained from glass compositions by means of catalysis

crystallization and consisting from one to several crystalline mineralogical phases

uniformly distributed in the remaining glass phase. Microstructure assessment, as

revealed by electron microscopy, showed a dense glass-ceramic structure with crystal

dimensions approximately 1 μm. The composition's mineralogical composition, as

demonstrated by X-ray diffraction, revealed that the predominant crystalline phase is

anorthite, whereas additional crystalline phases include albite and lithium disilicate. The

glass density was found to be up to 2720 kg/m³; the porosity less than 0.02%; and

bending strength was up to 150 MPa. However, the composition is heated to

temperatures that require addition of at least one crystallization catalyst to effect the

various crystalline phases, and to that extent the composition, article and corresponding

process are relatively cumbersome and prone to inaccuracy should mistakes occur during

catalyst addition. Bulk processing of relatively homogeneous mined mineral material has also

resulted in the creation of numerous ceramic tile products of varying quality and

durability. For instance, conventional ceramics produced by processing mixtures of

natural mineral constituents and admixtures can be classified according to their glass

content as non- vitreous, semi-vitreous, and vitreous. Non-vitreous ceramic, of which

Dai-Tile is an example, is generally manufactured from clay, talc, and carbonate

minerals, and has water absorption greater than about 7%. No fluxing minerals such as

feldspar are used in these compositions. Non- vitreous Dai-Tile of this type has a water

absorption of 13-14%, as measured by ASTM C373. This type of tile has virtually no

glass content, and gets its structural integrity from solid-state reactions and sintering.

Semi- vitreous ceramic, of which Balmor is an example, generally has some glass content

and corresponding water absorption between about 4% and about 7%. This is a red body

product, its color due to its natural iron content. Such bodies are often made of natural

clay-containing earth mixtures which contain natural quartz and feldspar. The latter acts

as a fluxing agent to produce a liquid phase during firing, said liquid phase converting to

glass during cooling. Vitreous ceramic, including porcelain tile, of which Granitifϊandre

Kashmir White is an example, has less than 4% water absorption. True porcelain

products typically have water absorption values less than about 0.5%. These materials

are primarily produced from the raw materials kaolinite clay, quartz, and feldspar. They

have a high glass content (typically 20-30%), and are also characterized by a lack of

crystalline phases that have precipitated from the melt during cooling. They often contain the mineral mullite (3 Al₂O₃-2 SiO₂) formed at elevated firing temperatures from solid

state decomposition of the kaolinite raw material.

Commercially available ceramic-tile materials - non- vitreous

Figure 1 is the scanning electron microprobe back-scattered electron (BSE) image

of the non- vitreous commercial ceramic tile manufactured by Dai-Tile™. This BSE

image illustrates the typical microfabric of this non- vitreous ceramic tile dominated by

discrete flaky particles (1 and 2) that are cemented (sintered) with no apparent glass

matrix. The Energy Dispersive X-ray (EDX) microchemical analysis spectra of the

dominant flaky particles show a magnesium-silicate chemistry. This composition

corresponds with the mineral "enstatite" (MgO-SiO₂) identified in the X-ray diffraction

analysis (XRD) performed on this ceramic tile sample. The enstatite mineral phase did

not "grow" or crystallize out of a melt, since none exists, but instead was formed as a

high temperature pseudo-morphous solid state replacement mineral for an original largely

talc feedstock material. Talc is a hydrated magnesium silicate mineral Mg₃Si₄O_1O(OH)₂).

Light colored (white) reaction rims (3) surround voids (black), some of which

contain partially dissolved particles (4). EDX analysis indicates that the rims (3) possess

a magnesium aluminum silicate chemistry that corresponds with the mineral cordierite

(MgO-Al₂O₃-SiO₂) detected by XRD analysis. The partially dissolved particles in the

center of some of the voids have a magnesium oxide chemistry typical of periclase. The

abundance of this MgO material was too low to be detectable in XRD analysis.

Minor angular particles (5) with a silica chemistry corresponds to the composition

of quartz (SiO₂) detected as a minor component in this ceramic tile by XRD analysis. The abundant void space (black) illustrates the high porosity of this non- vitreous

ceramic tile material (6). The absence of significant glassy matrix in this material causes

poor grain-to-matrix bonding contact (7). Both of these physical properties contribute to

greater water absorption, lower hardness and lower modulus of rupture (MOR — a

measure of mechanical strength) determined for this ceramic tile.

Commercially available ceramic-tile materials — semi-vitreous

Figure 2 is the scanning electron microprobe back-scattered electron (BSE) image

of the Balmor™ semi- vitreous commercial ceramic tile. Figure 2 illustrates the typical

microfabric of this semi- vitreous ceramic tile comprised of partially to completely

dissolved primary mineral grains. EDX analyses of these mineral grains revealed the

chemical compositions, which correlate to the specific minerals identified by XRD

analysis as being constituents of this tile material. These include potassium-feldspar (10),

plagioclase feldspar (11), quartz (12) and goethite (Fe(OH)₂) (13).

These primary mineral grains are cemented by a semi-continuous amorphous glass

matrix. The EDX microchemical analysis of two glassy matrix areas (14 and 15) shows

that the particular ratios of the cations K, Na, and Ca in the two glassy areas appear to be

similar to the two adjacent feldspar compositions (compare 10 with 14 and 11 with 15).

This similarity indicates that glass compositions may vary with respect to the cation

composition, and are influenced by the specific cation constituents within the adjacent

mineral grains that melt or dissolve to form the glass matrix material.

Figure 2 reveals that the glassy matrix of this semi- vitreous ceramic tile is semi-

continuous resulting in a moderate degree of retained porosity 16. This porosity is largely, but not completely, unconnected resulting in lower water absorption properties.

The primary grains are not entirely bonded (17) to the glassy matrix which causes a

reduction in the durability and hardness of the material.

Figure 2 also shows no secondary crystallite minerals within the glassy matrix.

No evidence is indicated that new crystalline mineral phases have precipitated from the

melt during the cooling process.

Commercially available ceramic-tile materials — vitreous

Figure 3 is the scanning electron microprobe back-scattered electron (BSE) image

of the Granitifiandre Kashmir White vitreous porcelain ceramic tile. This BSE image

illustrates the typical microfabric of this vitreous ceramic tile comprised of remnants of

partially dissolved primary grains. The EDX microchemical analysis of some of these

grains correlates with the XRD analysis to confirm that the mineralogy of this ceramic

tile is dominated by quartz (20), plagioclase feldspar (21) and zircon (22).

Figure 3 reveals that the quartz grain boundaries show evidence of significant

dissolution (20) while the feldspar grains are severely to completely melted or dissolved

(21). The minor zircon grains were evidently an admixture to achieve a mottled texture

in the porcelain tile body (surface 22). The glassy matrix appears to be continuous,

leaving only a few isolated voids or pores and producing low water absorption properties

(23).

Figure 3 also shows no apparent secondary crystallite minerals within the glassy

matrix and suggests that no such secondary minerals formed from the melt. However,

mullite — a mineral formed through solid state transformation from kaolinite — was identified in XRD analysis. Because of its typical needle-shaped crystal shape and very

small particle size, its presence in this ceramic was not positively identified in the BSE

analysis. The total atomic weight (density) of mullite may be too similar to the glass

matrix rendering it indistinguishable from the glass.

As discussed above, inefficiencies involving conventional methods of processing

waste minerals such as mine tailings, and the structural and compositional limitations

inherent in conventional ceramic products — particularly with respect to porosity and

corresponding water absorption, diminished hardness and low modulus of rupture —

demonstrate that a dual need exists for: (1) an effective and efficient strategy to reclaim

mineral wastes such as mine tailings at low cost and high safety; and (2) a low cost and

easily manufactured non-clay vitreous synthetic rock material with superior, and

heretofore collectively unavailable, characteristics including low porosity;

impermeability without glazing; high-plasticity for subsequent reformation; and high

strength and durability. The disclosed invention addresses these dual needs

simultaneously.

BACKGROUND OF THE INVENTION

Mine tailings and mine reclamation efforts have evoked enormous environmental

concerns in the United States and abroad. Tailings are waste products remaining in

containment areas or discharged to receiving waters after metals are extracted from a

particular site, and consist primarily of waste rock containing a variety of rock forming

minerals, including as major constituent groups crystalline silica, feldspars and clay

minerals; with minor constituent groups including carbonates, sulfates, sulfides and micas. Pollution issues associated with mine tailings relate to the structural integrity and

stability of tailings containment areas and the potential for pollution impacts should

containment failure occur. At the heart of these concerns is the pollution potential of

mine tailings on ground and surface water, and correspondingly how such potential

pollution affects people living in the immediate vicinity of tailings containment areas.

The need for effective mine reclamation strategies, and safe disposition of

potentially hazardous mine tailings, is widely recognized in the mining and

environmental industries alike. There is no legitimate doubt that disposing of mine

tailings in a safe manner, as opposed to continually attempting their containment, is

desirable from both an environmental safety and economic point of view. Likewise,

other mineral waste materials raise similar environmental contamination concerns, and

the need for their safe and effective disposition is also well acknowledged.

As far back as ancient Mesopotamia, researchers have located what they believe to

be basalt rock slabs formed from silt. It is believed that inhabitants used the basalt rock

as a main staple in the region for a variety of purposes, including pottery, architecture,

writing materials, art objects and tools. In simulation studies to recreate the basalt rock

from silt, researchers were able to approximate the composition and texture of the basalt

rock using local alluvial silt as raw starting material, and heating the material within a

defined temperature range over a sustained time period. The resulting basalt rock was

characterized by matted clinopyroxene crystals embedded in a glassy matrix, with

starting material remnants either rarely appearing in, or completely absent from, the final

basalt rock. The basalt rock was most likely of limited strength, as it lacked an aggregate microstructure. Due to the observed presence of many large pores, some as big as 3 mm,

the basalt had high water absorption, likely well in excess of 7%.

In more recent examples of waste materials, fly ash and bottom ash from burning

coal for electric power are largely incombustible residuals formed from inorganic

minerals in coal. Roughly hundreds of million tons is produced every year in the USA

alone. Fly ash and bottom ash are also produced in waste incinerators and biomass-

fueled power plants. Slag mineral waste materials result from metal processing

operations. Quarry and dredging operations often produce silicate waste materials such

as fines or slimes that must be disposed of in a safe manner.

Relatively pure mineral materials (kaolinite clay, feldspar, quartz, talc, etc.) have

conventionally been used to manufacture a variety of ceramic materials with varying

compositions and degrees of quality. As previously described, non-vitreous Dai-Tile,

semi-vitreous Balmor Tile and vitreous Granitifiandre Kashmir White tile represent a

very few. However, these and a vast array of other conventional ceramic products

(ceramic tile, dinnerware, sanitaryware, etc.) are typically manufactured by methods that

rely on the plasticity and bonding (in the unfired state) of clay — -largely kaolinite — and

generally use relatively pure raw materials. As previously stated, conventional ceramics

also demonstrate a number of undesirable characteristics, including moderate to high

porosity and water absorption, low hardness and strength, and the absence of secondary

crystallite formation upon cooling, which contributes to product durability. Also, in the

manufacture of conventional ceramics, considerable concern is placed on the quality and

purity of the raw material ingredients. Further, contaminants in the raw materials can cause considerable damage to the quality of the conventional product in terms of

structural integrity and defects in the cosmetic properties. Surprisingly, Applicant's

process and composition are tolerant of higher concentrations of many materials that are

considered contamination in conventional ceramics manufacture. Such materials include

iron, magnesium, manganese, sulfur, and their compounds.

The need exists in the environmental clean-up industry to develop an effective and

efficient strategy for reclaiming mines, disposing of mine tailings after mineral extraction

at the mine is complete, disposing of mine development rock, disposing of fly ash and

bottom ash from power plants or incinerators, disposing of slag, and disposing of fines or

slimes. An equally significant need exists in the synthetic rock industry to produce a low

porosity, easily manufactured, low absorption vitreous tile in a cost effective and

relatively fast manner.

SUMMARY OF THE INVENTION

The applicant's invention provides a crystalline and glass composition derived

from processing raw mine tailings and similar waste materials, which can be used to

create valuable articles of manufacture and products for a wide variety of uses,

particularly, but without limitation, in the commercial and residential construction

industry, for example floor, wall, and roof tile, brick, blocks, siding, panels, pavers,

countertops, aggregates for road base, and other building materials. The unique

composition comprises a clast phase, a glass phase, and a crystalline phase. Said clast

phase is further comprised of mineral grains, mineraloid grains, glass spherules, or rock

fragments, any of which may have been partially melted, or partially dissolved, or

partially transformed by chemical reaction. Said glass phase provides a matrix that

cements together the clasts. Said crystalline phase is fully enveloped by the glass phase,

having formed by growth from the melt. The unique composition of clasts fused together

by a unique glass phase, which further comprises a newly formed crystalline phase, is

characterized by a microscopic aggregate breccia (synthetic rock/glass matrix) structure

with superior physical and structural characteristics, including low porosity, low

absorption, increased strength and durability, retained plasticity to facilitate reformation

subsequent to initial processing, and readily distinguishable chemical attributes in

comparison to conventional synthetic rock materials, as demonstrated by scanning-

electron-microprobe analysis. The glass phase (glass matrix) is created as a result of partially melting a suite of

original raw mineral constituents, which may include feldspar, quartz and mineral

materials found in a wide variety of rock types, and which further may be present as

individual mineral grains (monomineralic) or as rock fragments (polymineralic). After an

optimal melting period, the resulting glass matrix is cooled over an optimal cooling

period, and during the cooling period unique silicate and non-silicate minerals with

varying proportions of iron, magnesium, calcium and sulfur crystallize from the melt to

form small crystallites distributed throughout the glass matrix. Importantly, the newly

formed secondary crystallites include specific inosilicate, tectosilicate and sulfate

compounds that are not present in the starting raw material, and are not found in

commercially-available ceramics in the same fashion. Occasionally, some of these

minerals may be found in commercially-available ceramics; however those minerals are

not secondary crystallites formed from a melt phase, but rather are remnants of the raw

starting material. The specific minerals formed in applicants ceramic materials are

influenced by the unique chemistry of the waste mineral feedstock materials such as

tailings, ash, etc.

Inosilicates are single-chain and double-chain silicate minerals. The Pyroxene

Group of inosilicates comprises single-chain, non-hydrated ferromagnesian chain

silicates. The Amphibole Group of inosilicates comprises double-chain, hydrated

ferromagnesian chain silicates. Wollastonite is a calcium silicate mineral in the

inosilicate group. Tectosilicates are framework silicate minerals, including minerals such as quartz

and the Feldspar Group. Plagioclase feldspar is a solid solution series of feldspar

minerals with varying amounts of sodium and calcium.

Sulfate minerals are a group of minerals containing sulfur. Gypsum and anhydrite

are calcium sulfates, with anhydrite forming the dehydrated form and gypsum the

hydrated form.

Pyroxenes, particularly enstatite and hypersthene (the iron containing version of

enstatite), as well as augite, diopside, bronzite, and pigeonite, are not conventionally

present in raw starting materials, and have not been detected in vitreous, semi- vitreous or

porcelain ceramics. Rather, pyroxenes have been detected, via X-Ray Diffraction

analysis (XRD) and Scanning Electron Microprobe analysis (microprobe) using an

Energy Dispersive X-ray Spectrometer (EDS), only in high porosity ceramics, such as the

non-vitreous ceramic Dai-Tile discussed above. However, microprobe analysis reveals

that those pyroxenes in the non- vitreous ceramic have a morphology that indicates to one

skilled in the art that they are the result of solid-state chemical reactions rather than

crystallization from a melt phase. Conversely, amphiboles, particularly in the form of

hornblende, have been detected in raw mine rock materials, but not in processed material,

because these compounds do not survive high temperature processing as a result of

dehydration and bond degradation during the heating process.

Wollastonite and plagioclase are common ingredients of some non- vitreous

conventional ceramics to achieve specific ceramic types and properties. However,

wollastonite and plagioclase have not been detected using microprobe analysis and EDS techniques as a newly crystallized phase in conventional ceramics, rather they appear as

sintered primary mineral grains.

Anhydrite and/or gypsum are not conventionally present in raw starting materials,

and have not been detected in conventional non-vitreous, semi- vitreous or vitreous

ceramics.

Applicant's compositions and articles of manufacture comprise both original

tailings fragments as well as newly formed mineral phases, which renders them

compositionally distinct not only from the raw mine tailings starting material, but - more

importantly — from conventional synthetic rock compositions and corresponding articles

of manufacture. A key compositional distinction between the raw starting material,

applicant's compositions and articles, and conventional synthetic rock compositions is

the presence or absence of inosilicate minerals, specifically pyroxenes, wollastonite,

tectosilicates, specifically plagioclase feldspar, and sulfates, specifically anhydrite. As

more fully set forth below, applicant's compositions and articles contain pyroxene

inosilicates, newly formed plagioclase, wollastonite and anhydrite, which heretofore have

not been detected in low porosity, vitreous synthetic rock materials. Specific pyroxene

minerals that may form in this synthetic rock may include, but are not limited to, one or

more of the following: augite, diopside, hypersthene, pigeonite, bronzite and enstatite.

In addition, applicant's invention employs a unique heating and cooling strategy,

which completely obviates the need for the addition of crystallization catalysts. That is,

heating of the raw material to a temperature at which some, but not all, of the components

of the raw material begin to at least partially melt. At these temperatures, a liquid phase is created that can flow to coat individual aggregate particles, bind them together, and fill

in void spaces. The liquid phase can also begin to dissolve additional solid material.

Upon cooling at reasonable unquenched rates, this liquid phase can partially crystallize

without the need for addition of nucleation additives because, due to partial melting, there

are already present solid surfaces to initiate crystallization. Mechanical pressure to

squeeze the material at temperature can help to distribute the liquid phase among the

various solid surfaces and increase binding. Vacuum to remove gas from void spaces can

help to eliminate resistance to filling in the voids with the liquid phase.

Typically the first components of the raw material to liquefy are glass particles or

feldspars, many of which liquefy at temperatures of approximately 1050 to 1300 degrees

C. Preferably, the raw material comprises glass or feldspar that becomes liquid at

temperatures in the range of 1100 to 1200 degrees C. Cooling from these temperatures

preferably takes place at a rate slow enough to allow crystallization to occur, preferably

about 1 to 50 degrees C per minute, more preferably about 5 to 20 degrees C per minute,

and most preferably about 10 degrees C per minute when cooling is initiated from the

peak temperature for the first few hundred degrees of cooling. Cooling at a maximum

rate of 10 degrees C per minute is also especially preferred as the material passes through

the temperature range of 600 to 500 degrees C, to avoid fracture due to the associated

volume change of the beta-to-alpha phase transition of any quartz that may be present in

the material.

In the embodiments and examples of the present invention that follow, an amount

of mine tailings, for example Historic Idaho-Maryland Mine Tailings ("HIMT"), containing both rock fragments and individual mineral grains, is heated in a forming

chamber to an optimal temperature, preferably in the range of 1100 to 1200 degrees C₅

and thereby partially melted over an optimal period of time, preferably about 0.5 to

6 hours. During the partial melting process, the HIMT raw material is simultaneously

exposed to pressure modification, which preferably is the application of mechanical force

to the material in the range of 1 to 200 psi, and which further may also be the application

of vacuum to reduce the absolute pressure to within the range of about 1 to 600 mbar in

order to remove interstitial gas phase.

Heating the HIMT raw material with pressure modification results in a partially

melted matrix, which is then allowed to cool over an optimal period of time. During the

cooling period, newly formed mineral crystallites with varying proportions of silicon,

aluminum, iron, magnesium, calcium, and sulfur crystallize from the initial raw material

melt to form small crystallites distributed throughout a glass matrix. As previously

stated, the invention does not employ added crystallization catalysts or nucleating agents

to facilitate the crystallization process.

The newly formed crystallized minerals occurring in the glass matrix comprise a

combination of minerals from the Pyroxene Group, Plagioclase Feldspar Group and

Sulfate Group. Morphological characteristics of the newly crystallized minerals indicate

their secondary growth from the initial raw material melt, as opposed to from a solid state

glass reaction. Most notably, these secondary growth indicators include the newly

formed minerals' generally uniform size, crystalline morphology and uniform

composition throughout the glass matrix. In one embodiment, the invention provides a vitreous, non-porous, impermeable

polycrystalline composition comprising an amount of clasts, an amount of glass matrix,

and an amount of at least one secondary crystalline phase. Said clasts comprise grains of

single minerals, such as quartz, or rock fragments, or unmelted glass fragments, or

mineraloid grains. Said glass matrix is distributed between the clasts, bonding to them

and filling in the nearly all of the interstitial space. Said at least one secondary crystalline

phase is contained within the glass matrix, and is comprised of crystals formed from a

melt with a mineral composition selected from the group consisting of ferromagnesian

minerals, pyroxenes (for example, clinopyroxene, orthopyroxene, augite, diopside,

hypersthene, pigeonite, bronzite, enstatite), illmanite, rutile, wollastonite, cordierite, and

anhydrite.

In one embodiment, the invention provides a method for processing mine tailings

resulting in a vitreous, non-porous, impermeable polycrystalline composition. Said

method comprises air drying a sampling of mine tailings to less than 3% moisture;

screening the mine tailings to remove material larger than 516 microns; and calcining the

mine tailings in air at approximately 900 degrees C. The mine tailings are then

mechanically compacted in a tube with an approximate pressure of 350 psi at an

approximate temperature of 1130 degrees C for approximately 60 hours, and

subsequently cooled at a rate of approximately 1 to 3 degrees C per minute, forming said

composition, comprising a clast phase, a glass phase, and at least one crystalline phase.

Said clast phase comprises grains of single minerals, such as quartz, or rock fragments.

Said glass phase is distributed between said clast phase, bonding to clast particles and filling in nearly all surrounding interstitial space. Said at least one crystalline phase is

contained within said glass phase, and comprises crystals formed from a melt with a

mineral composition consistent with minerals selected from the group consisting of

bronzite, augite and pigeonite.

In another embodiment, the invention provides a method for processing mine

tailings resulting in a vitreous, non-porous, impermeable polycrystalline composition.

Said method comprises air drying a sampling of mine tailings to less than 3% moisture;

mine tailings in air at approximately 900 degrees C. The mine tailings are then

mechanically compacted in a tube with an approximate pressure of 300 psi at an

approximate temperature of 1140 degrees C for approximately 6 hours, and subsequently

cooled at a rate of approximately 10 to 20 degrees C per minute, forming said

Said glass phase is distributed between said clast phase, bonding to clast particles and

filling in nearly all surrounding interstitial space. Said at least one crystalline phase is

contained in said glass phase and comprises crystals formed from a melt with a mineral

composition consistent with minerals selected from the group consisting of bronzite,

augite, pigeonite, anhydrite and ilmanite.

In another embodiment, the invention provides a method for processing

metavolcanic mine development rock resulting in a vitreous, non-porous, impermeable

polycrystalline composition. Said method comprises air drying a sampling of the development rock to less than 3% moisture; and screening the development rock through

a 516 micron screen. Development rock powder is then processed through the apparatus

described in U.S. Patent No. 6,547,550 (Guenther) at a temperature of approximately

1160 degrees C, with mechanical pressure oscillating between approximately 30 psi and

160 psi for a defined time period, in a partial vacuum atmosphere for approximately 60

minutes, and subsequently cooled at an approximate rate of 5 to 15 degrees C per minute,

forming said composition, comprising a clast phase, a glass phase and at least one

crystalline phase. Said clast phase comprises polymineralic and monomineralic clasts.

composition consistent with minerals selected from the group consisting of augite,

pigeonite, maghemite and ilmanite.

In another embodiment, the invention provides a method for processing coal fly

ash resulting in a vitreous, non-porous, impermeable polycrystalline composition. Said

method comprises air drying a sampling of the coal fly ash to less than 3% moisture;

screening the coal fly ash with a 516 micron screen; and thereafter calcining the coal fly

ash. The coal fly ash is then mechanically compacted at an approximate pressure of

300 psi in a tube at an approximate temperature of 1115 degrees C for approximately

10 hours, and subsequently cooled at an approximate rate of 10 to 20 degrees C per

minute, forming said composition, comprising a clast phase, a glass phase, and at least

one crystalline phase. Said clast phase comprises remnant clasts from the original feedstock constituents. Said glass phase is distributed between said clast phase, bonding

to clast particles and filling in nearly all surrounding interstitial space. Said at least one

crystalline phase is contained in said glass phase and comprises crystals formed from a

melt with a mineral composition consistent with minerals selected from the group

consisting of wollastonite, plagioclase feldspar, anhydrite, and calcium sulfate.

In another embodiment, the invention provides a method of processing waste

materials selected from the group consisting of mine tailings, waste rock, quarry waste,

slimes, fly ash, bottom ash, coal ash, incinerator ash, wood ash, and slag, resulting in a

vitreous, non-porous, impermeable polycrystalline composition. Said method comprises

subjecting the waste materials to a screening apparatus; conveying the waste materials

from said screening apparatus to a heated rotating chamber for chemical transformation;

conveying the waste materials from said heated rotating chamber to a second heated

chamber optionally fixed with a vacuum; conveying the waste materials from said second

heated chamber to a third heated chamber positioned within a heating element; applying

pressure to the waste materials in said third heated chamber forming a hybrid rock;

extruding said hybrid rock through a die device and removing said hybrid rock from said

third heated chamber for subsequent use or further modification.

The benefits, advantages and surprising discoveries resulting from the present

invention are, in a word, remarkable. First and foremost, a surprising discovery

regarding applicant's invention is the presence of pyroxene inosilicates in the final

composition and corresponding articles. Heretofore, pyroxene mineral compounds have

not been detected in vitreous, low-porosity, low absorption synthetic rock materials such as applicant's present invention. Rather, pyroxenes have only been conventionally

detected in highly porous, non- vitreous materials.

Also surprising is the fact that applicant's invention achieves maximum

crystallization without the addition of crystallization catalysts or other nucleating agents.

The raw material in applicant's invention is not heated beyond its melting point, but

rather is only partially melted, which preserves crystallization nuclei sites already present

in the glass matrix. Conversely, conventional synthetic rock compositions must employ

crystallization catalysts to facilitate crystal formation because corresponding raw

materials are heated to above their melting point and completely melted to a homogenous

state during processing, which destroys potential crystallization sites. Conventional

crystallization catalysis is required to provide a site for crystallization.

Yet another surprising discovery regarding applicant's invention is that the

invention's glass matrix can comprise various amounts of glass, but that with less than

approximately 20% glass the composition achieves impermeability. Conventional low or

non-permeable synthetic rock materials require a high glass content to achieve

impermeability.

The invention also has the advantage of providing compositions of matter

comprising crystalline particles within a glass-binding liquid matrix, which allows the

compositions to maintain a significant amount of plasticity at high temperature, unlike

conventional clay tile. With this heightened plasticity level the compositions can, while

initially heated or re-heated, be pressed, rolled or injected into other shapes and a variety

of useful products after initial preparation. For instance, fine grained versions of the solid compositions can be pressed into aggregates and cobbles for a variety of construction

uses, including for use in cement, road base and cobblestones. Alternatively, commonly

known abrasives, such as silica carbide, quartz and garnet, can be added to the

composition for subsequent use in sanding blocks and grinding wheels.

Another advantage of the present invention is that the solid compositions and

corresponding articles of manufacture are impermeable without the need for glazing. The

invention's impermeability is directly related to the fact that, unlike conventional

synthetic rock materials, the composition and articles contain essentially zero open

porosity, due to the continuous glass matrix structure surrounding crystallites distributed

throughout therein. With the exception of certain rare vitreous expensive clay products,

such as porcelain, conventional synthetic rock and ceramic products require glazing to

achieve impermeability.

As previously stated, applicant's invention contains virtually zero open porosity,

which results in less porous and more impermeable articles as compared to conventional

ceramic materials. Surprisingly, voids (closed pores) may be induced in applicant's

invention to result in a lighter weight construction-type material, without compromising

the invention's impermeable characteristics.

Other aspects and alternatives or preferred embodiments of the invention exist.

They will become apparent as the specification proceeds. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a micrograph obtained from scanning electron microprobe analysis of

commercially available (Dai-Tile) non-vitreous ceramic tile.

Figure 2 is a micrograph obtained from scanning electron microprobe analysis of

commercially available (Balmor) semi-vitreous ceramic tile.

Figure 3 is a micrograph obtained from scanning electron microprobe analysis of

commercially available (Granitifiandre, Kashmir White) vitreous ceramic tile.

Figure 4 is a micrograph obtained from scanning electron microprobe analysis of

an article of manufacture resulting from Applicant's method of processing mine tailings,

including an illustration of the article's composition.

Figure 5 is a micrograph obtained from scanning electron microprobe analysis of

including an illustration of the article's composition.

Figure 6 is a micrograph obtained from scanning electron microprobe analysis of

an article of manufacture resulting from Applicant's method of processing mine

development rock, including an illustration of the article's composition.

Figure 7 is a micrograph obtained from scanning electron microprobe analysis of

an article of manufacture resulting from Applicant's method of processing coal fly ash,

including an illustration of the article's composition.

Figure 8 is a schematic flowchart depicting an apparatus and method of processing

waste mineral materials. DETAILED DESCRIPTION OF THE INVENTION

The First Embodiment

This embodiment is an apparatus and process for processing mine tailings

employing a slow cooling schedule, which results in Applicant's composition and

corresponding articles of manufacture.

Table 1. Composition of some feed materials

EXAMPLE 1

A sample of tailings from the Idaho-Maryland gold mine, having the general

composition shown in Table 1, was air-dried to less than 3% moisture and screened to

remove material larger than 516 microns (30 mesh). The raw tailings material was

calcined in air at 900 degrees C. Following calcining, the material, without additives, was mechanically compacted using a ram at a pressure of approximately 350 psi within a

nitride-bonded-silicon-carbide process tube at a temperature of 1130 degrees C for an

extended period of time, approximately 60 hours at temperature. The material was then

slowly cooled, at a rate of 1 to 3 degrees C per minute, forming a synthetic rock hybrid

material, which was then removed from the process tube. Test specimens of the resulting

synthetic rock hybrid material had an average modulus of rupture of about 85 MPa

(12320 psi), and an average water absorption of about 0.3% as determined by method

ASTM C373. Other resulting data are shown in Table 2.

Table 2. Physical properties of example synthetic rock hybrid materials.

Ex. 1 Ex. 2 Ex. 3 Ex. 4 modulus of rupture (psi) 12320 6060 9280 8230 apparent porosity (%) ASTM C373 0.7% 6.8% 2.3% 1.8% water absorption (%) ASTM C373 0.3% 3.2% 0.8% 0.7% apparent specific gravity ASTM C373 2.67 2.32 2.83 2.53 bulk density (g/cm3) ASTM C373 2.65 2.16 2.76 2.49

Figure 4 is the scanning electron microprobe back-scattered electron (BSE) image

of this synthetic rock hybrid material of Idaho Maryland mine tailings feedstock. Figure

4 illustrates the three characteristic phases typical of the unique microfabric of this

synthetic rock material. These three phases include clasts (partially dissolved remnant

primary grains of the tailings feedstock); a glass phase derived from the partial melting of

primary mineral grains; and a secondary crystalline phase comprised of similarly sized

crystallites that occur in the glass phase. The latter secondary minerals crystallized from the melt prior to cooling and formation of the glass phase. Figure 4 shows a remnant

primary quartz grain with rounded edges indicating dissolution of its formerly angular

grain boundaries (31). The nearly complete melting of most other primary mineral

constituents of the original feedstock components such as feldspar leaves little evidence

of their existence in this synthetic rock other than mottled areas that retain the chemical

signature of the parent mineralogy (32).

The glass phase (33) with an aluniinosilicate composition contains trace amounts

of cations such as potassium, calcium, sodium, magnesium, and iron (33). EDS

microchemical analysis of the glass throughout the ceramic indicates that the glass

composition is heterogeneous and varies with respect to the aluminum: silicon ratio as

well as the trace cation content (34).

The newly formed (secondary) crystallite comprises the crystalline phase of this

synthetic rock. The longer processing time resulted in secondary crystallites comprising

40-50% of the volume of this material. The crystallites appear in two recognizable

morphologies each with distinct chemistries as determined by EDS. Some crystallites

appear in narrow lath and skeletal shapes and occur singly and in clusters (35).

Crystallites of this morphology uniformly possess a chemistry most similar to the

bronzite species of pyroxene having high magnesium but low calcium and iron contents

(35). The size of the lath shaped crystallites ranges from 1 to 3μm in width and from 5 to

25μm in length.

The other common morphology of crystallites is an equant blocky shape similarly

occurring singly and in clusters (36). This latter crystallite morphology is associated with calcium to iron ratios similar to augite or pigeonite varieties of pyroxene having high

calcium but low iron contents. The size of these blocky crystallites ranges from 4 to

15μm.

The continuous glass phase in this synthetic rock material leaves widely spaced

isolated voids with little or no communication between them resulting in very low

absorption values (37).

The Second Embodiment

This embodiment is a method of processing mine tailings employing a fast cooling

schedule, which results in Applicant's composition and corresponding articles of

manufacture.

EXAMPLE 2

A sample of tailings from the Idaho-Maryland gold mine, having the general

calcined in air at 900 degrees C. Following calcining, the material, without additives,

was mechanically compacted using a ram at a pressure of approximately 300 psi within a

nitride-bonded-silicon-carbide process tube at a temperature of 1140 degrees C, with a

residence time of approximately 6 hours at temperature. The material was then extruded

through a rectangular die (15.2 by 1.3 cm) with a land length of 3.5 cm, and subsequently

cooled at a rate of about 10 to 20 degrees C per minute, forming a synthetic rock hybrid

material. Test specimens of the resulting synthetic rock hybrid material had an average modulus of rupture of about 42 MPa (6060 psi), and an average water absorption of about

3.2 % as determined by method ASTM C373. Other resulting data are shown in Table 2.

Figure 5 shows the scanning electron microprobe back-scattered electron (BSE)

image of the resulting synthetic rock hybrid material. Figure 5 illustrates the three

characteristic phases typical of the unique microfabric of this synthetic rock material.

These three phases include clasts (partially dissolved remnant primary grains of the

tailings feedstock); a glass phase derived from the partial melting of primary mineral

grains; and a secondary crystalline phase comprised of similarly sized crystallites

enveloped in the glass phase. The latter secondary minerals crystallized from the melt

during cooling, likely prior to the formation of the glass phase. Figure 5 shows a remnant

grain boundaries (41). The nearly complete melting of most other primary mineral

constituents of the original feedstock components leaves little evidence of their existence

in this synthetic rock.

The glass phase (42) with an aluminosilicate composition contains trace amounts

of cations such as potassium, calcium, sodium, magnesium, and iron (42). EDS

well as the trace cation content (43).

Four newly formed secondary crystalline phases are apparent in this synthetic rock

material including two distinct pyroxene types, anhydrite and ilmanite. Pyroxene

crystallites appear in two morphologies each with distinct chemistries as determined by EDS. One pyroxene crystallite morphology is a narrow lath shape (44). The lath type

pyroxenes uniformly possess a chemistry most similar to the bronzite species having high

magnesium but low calcium and iron contents (44). The crystallite sizes range from 1.5

to 3 μm in width and from 5 to 50 μm in length. The faster processing time to produce

this material (relative to Example 1) prevented complex cluster development of the

crystallites. Other pyroxene crystallites occur with an equant blocky shaped morphology

(45). This latter type pyroxene occurs singly and in simple clusters. This latter pyroxene

crystallite morphology is associated with calcium to iron ratios similar to augite or

pigeonite varieties with high calcium but low iron contents. The blocky crystallites range

from 1 to 5 μm.

Sulfur in this synthetic rock has combined with calcium to form crystallite clusters

of anhydrite (46). Individual crystallites within the clusters range from 2 to 7 μm in size.

Small similarly sized crystallites of ilmanite (iron titanium oxide) of 1 to 5 μm in

size appear randomly arranged in the glassy matrix (47).

The continuous glass phase in this synthetic rock material leaves few and widely

spaced isolated voids (48) with little or no communication between them, resulting in

very low absorption values.

The Third Embodiment

This embodiment is a method of processing metavolcanic mine development rock

employing a fast cooling schedule, which results in Applicant's composition and

corresponding articles of manufacture. EXAMPLE 3

A composite of drill-core samples taken from metavolcanic (andesite, dacite,

diabase, and others) rock from the Idaho-Maryland mine ("development rock") was air-

dried to less than 3% moisture, and ground to a size fine enough to pass 100% through a

516-micron (30-mesh) screen. The development rock powder had a composition as

shown in Table 1. The development rock powder, without additives, was processed

through the apparatus described in US Pat. 6,547,550 (Guenther) at a temperature of

1160 degrees C, with a mechanical pressure oscillating between about 160 psi and 30 psi

with a period of oscillation of 10 minutes, in a partial vacuum atmosphere (about

170 mbar absolute pressure), with a residence time of about 60 minutes before extruding

the consolidated plug of synthetic rock hybrid material. Following the extrusion, the plug

was cooled at a rate of about 5 to 15 degrees C per minute. Test specimens of the

resulting synthetic rock hybrid material had an average modulus of rupture of about

64 MPa (9280 psi), and an average water absorption of about 0.8% as determined by

method ASTM C373. Other resulting data are shown in Table 2.

Figure 6 is the scanning electron microprobe back-scattered electron (BSE) image

of the resulting synthetic rock material from composite Idaho Maryland development

rock feedstock. Figure 6 illustrates the three characteristic phases typical of the unique

microfabric of this synthetic rock material that collectively comprise an aggregate (or

breccia) arrangement. These three phases include partially dissolved remnant primary

grains of the original metavolcanic feedstock constituents; a glass phase derived from the

partial melting of primary mineral grains; and secondary crystalline phases comprised of similarly sized crystallites enveloped in the glass phase. The latter secondary minerals

crystallized from the melt during cooling, likely prior to the formation of the glass phase.

Figure 6 shows numerous remnant grains of a variety of primary constituents forming a

relatively coarse clasts fraction. These primary lithic grains include polymineralic

metavolcanic rock fragments (51) and monomineralic mineral grains (52). Specific

minerals that occur either in monomineralic grains comprised of a single mineral or

polymineralic rock fragments comprised of multiple minerals include plagioclase

feldspar (53); pyroxene (54); and remnants of degraded chlorite (55). Other primary

minerals inherited from the feedstock constituents that also occur but not illustrated in

Figure 6 include sphene, quartz and hematite.

The partial melting of feldspar (53) occurring in the metavolcanic feedstock

contributes to the formation of a melt phase that created a glass matrix upon cooling (56).

The rounded feldspar grain margins indicate dissolution or melting of its formerly

angular grain boundaries. The glass phase (56) with an aluminosilicate composition

contains trace amounts of cations such as potassium, calcium, sodium, magnesium, and

iron. EDS microchemical analysis of the glass throughout the ceramic indicates that the

glass composition is heterogeneous and varies with respect to the aluminum: silicon ratio

as well as the trace cation content (57).

Figure 6 illustrates the formation of the dominant secondary crystalline phase that

crystallized from the melt. Clusters of pyroxene crystallites appear in various locations

enveloped by the glass phase (58). The individual pyroxene crystallites within the

clusters possess an equant blocky morphology with calcium to iron ratios similar to augite or pigeonite varieties. Other secondary minerals that crystallized from the melt but

not illustrated in Figure 6 include maghemite (spinel group) and ilmanite (iron titanium

oxide).

The continuous glass phase of this synthetic rock material envelops nearly the

entire grain margin of the clasts resulting in widely spaced isolated voids (59). There is

little or no communication between the isolated voids resulting in the very low absorption

values determined for this synthetic rock hybrid material.

The unique structural attribute of this synthetic rock material is the aggregate

breccia microfabric created by the three important components that includes 1) the

primary remnant clasts, 2) the glass phase, and 3) the secondary crystallite phase. This

aggregate breccia structural arrangement of components (or constituents) creates a strong

aggregate microfabric with superior strength and durability properties unique to this

synthetic rock material.

The Fourth Embodiment

This embodiment is a method of processing coal fly ash employing a fast cooling

manufacture.

EXAMPLE 4

Coal fly ash material was obtained from a coal power plant, specifically Valmy

train 2 in Winnemucca, NV. The composition of the raw material is shown in Table 1.

The material was air-dried to less than 3% moisture, and screened to pass 100% through a 516-micron (30-mesh) screen. Following calcining, the calcined coal fly ash material,

without additives, was mechanically compacted using a ram at a pressure of

approximately 300 psi within a nitride-bonded-silicon-carbide process tube at a

temperature of 1115 degrees C, with a residence time of approximately 10 hours at

temperature. The material was then extruded through a cylindrical die, and subsequently

material. Test specimens of the resulting synthetic rock hybrid material had an average

modulus of rupture of about 57 MPa (8230 psi), and an average water absorption of about

0.7% as determined by method ASTM C373. Other resulting data are shown in Table 2.

Figure 7 is the scanning electron microprobe back-scattered electron (BSE) image

of the synthetic rock material fabricated from coal fly ash waste material feedstock.

Figure 7 illustrates the three characteristic phases typical of the unique microfabric of this

synthetic rock material that collectively comprise an aggregate structural arrangement.

These three phases include clasts of partially dissolved remnant primary grains of the

original fly-ash feedstock constituents; a glass phase derived from the partial melting of

primary mineral and fly-ash grains; and secondary crystalline phases comprised of

similarly sized crystallites enveloped in the glass phase. The latter secondary minerals

Figure 7 shows remnant grains of primary constituents that remain in this synthetic rock

including quartz (61) and fly-ash glass spherules (62).

The partial melting of fly-ash glass spherules — the dominant feedstock

constituent — created a melt phase that formed a continuous glass matrix upon cooling (63). The glass phase (63) with an aluminosilicate composition contains trace amounts of

cations such as potassium, calcium, sodium, magnesium, and iron. EDS microchemical

analysis of the glass throughout the ceramic indicates that the glass composition is

heterogeneous and varies with respect to the aluminum: silicon ratio as well as the trace

cation content (64).

Figure 7 illustrates the formation of up to four secondary crystalline phases that

crystallized from the melt during the cooling process. These secondary crystalline phases

include: clusters of wollastonite crystallites (65) some of which nucleated on remnant

primary quartz grains (61); lath-shaped plagioclase feldspar (66) and pyroxene (67)

crystallites randomly distributed in the glass phase; and blocky anhydrite crystallites

(calcium sulfate) not shown in Figure 7. The anhydrite phase is a major component of

this synthetic rock material and serves as a major receptacle for the sulfur that was a

dominant constituent of the coal fly-ash waste material.

Individual wollastonite crystallites range in size from 1 to 6 μm. The lath shaped

plagioclase and pyroxene crystallites range from 1 to 5 μm in width and 2 to 15 μm in

length. The larger blocky anhydrite phenocrysts are a size that can be resolved with the

polarized light microscope with typical sizes ranging from 10 to 70 μm.

The continuous glass phase of this synthetic rock material envelops the entire

grain margin of the primary and secondary mineral grains resulting in few if any isolated

voids (68). The predominant void space in this synthetic rock was inherited and

associated with the primary fly-ash spherules (69). There is little or no communication between any of the isolated voids resulting in the very low absorption values determined

for this synthetic rock material.

primary remnant clasts, which in this example include mineral grains and mineraloid

grains such as glassy fly-ash spherules, 2) the glass phase, and 3) the secondary crystallite

phase. The cluster development of the large wollastonite crystallites the crystallized

around primary quartz grains contributes to the coarse aggregate fraction (65). This

synthetic rock material.

The Fifth Embodiment

This embodiment is a method of processing waste mineral materials such as mine

tailings, ash, slag, slimes, and the like, which results in Applicant's composition and

corresponding articles of manufacture.

Referring to Figure 8, raw material for synthetic hybrid rock manufacture 100,

may be for example mine tailings, waste rock, quarry fines, slimes, fly ash, bottom ash,

coal ash, incinerator ash, wood ash, slag, or blends of these materials with each other or

with pure ceramic feed materials such as clay, feldspar, quartz, talc, and the like. Silicate

waste materials are particularly well-suited for use as raw material. Raw material 100 is

delivered to screening apparatus 120, which has an outlet 121 for oversize particles 122

with a size larger than a predetermined screen opening size, and which further has an outlet 123 for undersize particles 124 with a size smaller than a predetermined screen

opening size. Oversize particles 122 may be recycled to screening apparatus 120 via a

grinding process (not shown), or disposed of.

Undersize particles of raw material 124 are conveyed to a hopper 131 of rotary

calciner 130. Feed auger 137 is driven, for example by motor 136, and particulate raw

material is thereby conveyed to a heated rotating barrel 132. Barrel 132 is heated by any

of various means including but not limited to electric resistance heaters, gas burners, and

exhaust or waste heat from other processes. Drive 138 rotates barrel 132, which may

have a smooth interior surface, or alternatively may have a surface that is corrugated or

otherwise roughened, for example with lifters, to provide a means for the material to be

repeatedly lifted and dropped as it moves through the barrel. Barrel 132 is inclined at a

shallow angle from horizontal in order to slowly drive the powder toward the discharge

assembly 133. Calciner 130 optionally has gas inlet 135 for the addition of air or other

gases and vent 134 for the removal of combustion products or other gaseous

decomposition products. Calciner 130 is operated at temperatures below the point where

the material begins to soften and sinter, but at elevated temperatures such that the

material is preheated and dried. Other useful chemical transformations can be carried out

in the calciner, including but not limited to combustion of organic materials, conversion

of hydrated minerals to dehydrated oxides, desulphurization, decomposition of

carbonates, and the like. The process temperature for each of these operations varies, but

is generally in the range of 100 to 1000 degrees Celsius. Calcined particulate material 139 exits at a temperature within this range,

preferably about 800 to 1000 degrees Celsius, and passes through valve 140 to

hopper 150. Valve 140 can be closed to provide a vacuum-tight seal between hopper 150

and calciner 130. Preferably valve 140 is a high-temperature rotary valve that can

continuously flow material through while maintaining a pressure differential.

Hopper 150 is preferably thermally insulated, or alternatively provide with a

source of heat to maintain the temperature of particulate material. Vacuum outlet 151

may be provided for connection to vacuum 152. Vacuum removes entrained and

interstitial gas from particulate material and contributes to the production of void-free

synthetic hybrid rock material from a subsequent extrusion step. Vacuum can also reduce

the oxidation of minerals and can increase the variety or level of crystallization in the

resulting product.

Flange opening 161 of hopper 150 is connected to feeder 160 at flange opening

161. Feeder 160 may function as a reciprocating ram, or as an auger, or as both. Auger

162 is rotated by shaft 163 and drive 164, thereby conveying particulate synthetic hybrid

rock material forward into extruder barrel 180. The entire auger/drive assembly may be

moved axially, for example by means of hydraulic ram, 165 moving axially in hydraulic

cylinder 166 due to pressure created by pump or hydraulic power unit 167. The axial

motion of auger 162 also conveys particulate material into extruder barrel 180.

A typical operation cycle for using both auger and ram aspects of the invention

together is as follows. Under little, or none, or perhaps backward force from the

hydraulic ram 165, drive 164 rotates auger 162, which conveys particulate material into extruder barrel 180. When the available space in extruder barrel 180 is filled with newly

conveyed particulate material, drive 164 is shut down and auger 162 stops rotating.

Ram 165 is then energized by power unit 167 to provide an axial force on auger 162,

which in turn pushes on material in extruder barrel 180. Material is conveyed axially

down extruder barrel 180 in this manner for a predetermined distance. Once said

predetermined distance has been reached, the force applied by hydraulic ram is reduced,

and the cycle may be repeated.

Extruder barrel 180 may be constructed from a material with excellent resistance

to high temperatures, good thermal conductivity, acceptable strength, and excellent

resistance to wetting by or reaction with materials to be processed in the extruder.

Preferably, extruder barrel 180 is constructed from silicon carbide (SiC). Most

preferably, extruder barrel 180 is constructed from nitride-bonded silicon carbide (SiN-

SiC), for example Advancer™ material available from St. Gobain Industrial Ceramics.

Extruder barrel 180 is compressed between feeder 160 and spider 190 and

supported within furnace 170. Furnace 170 provides heat, for example by electrical

resistance heaters or by gas combustion, and is preferably a split-tube design for ease of

maintenance, and also preferably has multiple zones of temperature control along its

length. Furnace 170 provides heat to increase the temperature of extruder barrel 180 high

enough to fuse, sinter, partially melt, or otherwise accomplish the desired vitrification of

the material within. Within extruder barrel 180, particulate material fed by feeder 160 is conveyed

axially toward reducer die 181 and heated, thereby consolidating and vitrifying

particulate material into at least partially molten synthetic hybrid rock material.

Reducer die 181 connected to the end of extruder barrel 180 provides a resistance

to the flow of said at least partially molten synthetic hybrid rock material and thereby

increases the necessary pressure applied by ram 165 to convey the material, providing a

mechanism for consolidation of the material. Optional land die 182 connected to the end

of reducer die 181 may further increase the resistance to flow. In the absence of land die

182, a spacer may be used, for example an additional short length of barrel similar to

extruder barrel 180. At the discharge end of the extruder, that is where the land die or

spacer exits furnace 170, an insulator ring 183 made of strong, thermally insulating

material, preferably zirconia, is placed. Insulator ring 183 minimizes heat conduction

from the furnace to spider 190, and is captured in a recessed opening within spider 190.

Spider 190 is a stiff plate that allows passage of extruded synthetic hybrid rock

product 130 through a hole in the center while providing mechanical compression to

insulator ring 183, land die 182, reducer die 181 and extruder barrel 180. Spider 190 is

supported by a plurality of stiff springs 191, each reacting against a load cell 192

mounted on a fixed rigid support.

Extruded synthetic hybrid rock product 130 exits land die 182, proceeds through

insulator ring 183 and spider 190, and is supported and conveyed by a plurality of rollers

201 within heated chambers 200 and 220. The temperature in heated chambers 200 and

220 is maintained such that extruded synthetic hybrid rock material 230 remains deformable enough to be cut by cutters 210 attached to actuators 212. After cutting,

extruded synthetic hybrid rock material 230 may be removed from heated chamber 220

and cooled by various means to produce useful products. Alternatively, extruded

synthetic hybrid rock material 230 may be conveyed to subsequent operations such as

pressing, forming, rolling, molding, or glazing at a high temperature, thereby efficiently

using the heat in the material.

Claims

We Claim:

Claim 1 — A composition comprising, in combination, a fused mixture having:

a clast phase;

a glass phase; and

at least one crystalline phase,

wherein said at least one crystalline phase is comprised of newly-

formed crystallites dispersed in said glass phase.

Claim 2 - The composition of Claim 1 wherein said at least one crystalline phase

comprises crystallites having chemistries consistent with members of the

following mineral groups: pyroxene, plagioclase feldspar, wollastonite, or

sulfate groups of minerals.

Claim 3 - The composition of Claim 1 wherein said at least one crystalline phase

comprises crystallites having magnesium, calcium and iron concentrations

consistent with chemistries characterizing members of the pyroxene group

of minerals.

Claim 4 — The composition of Claim 1 wherein said at least one crystalline phase

comprises crystallites having chemistry consistent with members of the

pyroxene group of minerals having the chemistry (Mg,Fe²⁺)₂ [Si₂O₆].

Claim 5 — The composition of Claim 1 wherein said at least one crystalline phase

comprises crystallites having chemistry consistent with members of the pyroxene group of minerals having the chemistry

(Ca₅Na,Mg,Fe²⁺,Mn,Fe³⁺,Al,Ti)₂ [(Si₅Al)₂O₆].

Claim 6 - The composition of Claim 1 wherein said at least one crystalline phase

comprises crystallites having chemistry consistent with members of the

pyroxene group of minerals having the chemistry

(Mg₅Fe²⁺Ca)(Mg₅Fe²⁺)[Si₂O₆].

Claim 7 - The composition of Claim 1 wherein said at least one crystalline phase

comprises crystallites having chemistry consistent with members of the

pyroxene group of minerals having the chemistry Ca(Mg₅Fe)[Si₂O₆].

Claim 8 — The composition of Claim 1 wherein said at least one crystalline phase

comprises anhydrous CaSO₄.

Claim 9 — The composition of Claim 1 wherein said at least one crystalline phase

comprises crystallites having lath morphological characteristics consistent

with members of the pyroxene group of minerals.

Claim 10 — The composition of Claim 1 wherein said at least one crystalline phase

comprises crystallites having equant blocky morphological characteristics

consistent with members of the pyroxene group of minerals.

Claim 11 - The composition of Claim 1 wherein said at least one crystalline phase

comprises crystallites occurring either singly or in clusters.

Claim 12 - The composition of Claim 1 wherein said glass phase is heterogeneous and

comprises aluminum, silicon, and lesser concentrations of cations. Claim 13 - The composition of Claim 1 wherein said clast phase is partially dissolved and

comprises remnant primary clasts derived from original feedstock

constituents; and wherein said at least one crystalline phase comprises

secondary crystallites newly-formed from a melt.

Claim 14 - The composition of Claim 1 wherein said at least one crystalline phase is

comprised of crystallites having chemistry consistent with members of the

pyroxene group of minerals having the chemistries (Mg,Fe²⁺)₂[Si₂θ₆] and

(Ca₅Na₅Mg, Fe²⁺ ₅Mn₅Fe³⁺ ₅Al,Ti)₂ [(Si₅Al)₂O₆].

Claim 15 — The composition of Claim 14 wherein said clast phase is partially dissolved

and comprises remnant primary grains derived from original feedstock

constituents; and wherein said at least one crystalline phase comprises

secondary crystallites newly-formed from a melt.

Claim 16 - A composition comprising, in combination, a fused mixture having:

a clast phase;

a heterogeneous glass phase comprising aluminum, silicon, and lesser

amounts of cations; and

a plurality of newly-formed crystalline phases,

wherein said plurality of newly-formed crystalline phases is

dispersed in said glass phase and comprised of crystallites having

chemistry consistent with members of the pyroxene group of

minerals having the chemistries (Mg,Fe²⁺)₂ [Si₂O₆], (Ca₅Na₅Mg,

Fe²⁺,Mn,Fe³⁺,Al,Ti)₂ [(Si₃Al)₂O₆], (CaSO₄), and (FeTiO₃). Claim 17 — The composition of Claim 16 wherein said clast phase is partially dissolved

and comprises remnant primary clasts derived from original feedstock

constituents; and

wherein said plurality of newly-formed crystalline phases comprises

secondary crystallites newly-formed from a melt.

Claim 18 - A composition comprising, in combination, a fused mixture having:

a clast phase;

a heterogeneous glass phase comprising aluminum, silicon, and lesser

amounts of cations; and

a plurality of newly-formed crystalline phases,

wherein said plurality of newly-formed crystalline phases is

dispersed in said glass phase and comprised of crystallites having

constituent concentrations consistent with members of the pyroxene

group of minerals having the chemistries (Mg,Fe²⁺)₂ [Si₂O₆],

(Mg₅Fe²⁺Ca)(Mg₅Fe²⁺)[Si₂O₆], (CaSO₄), and (FeTiO₃).

Claim 19 - The composition of Claim 18 wherein said clast phase is partially dissolved

and comprises remnant primary clasts derived from the original feedstock constituents;

wherein said plurality of newly-formed crystalline phases comprises secondary

crystallites newly-formed from a melt.

Claim 20 - A composition comprising, in combination, a fused mixture having:

remnant clasts;

a glass phase; and a plurality of newly-formed crystalline phases,

wherein said plurality of newly-formed crystalline phases comprises

crystallites dispersed in said glass phase.

Claim 21 - The composition of Claim 20 wherein said remnant clasts are monomineralic

and polymineralic.

Claim 22 - The composition of Claim 20 wherein said remnant clasts comprise the

minerals plagioclase feldspar, pyroxene and degraded chlorite.

Claim 23 - The composition of Claim 20 wherein said glass phase is heterogeneous and

comprises aluminum, silicon, and lesser amounts of cations.

Claim 24 — The composition of Claim 23 wherein said cations comprise, in combination,

potassium, calcium, sodium, magnesium, and iron.

Claim 25 - The composition of Claim 20 wherein said plurality of newly-formed

crystalline phases comprises crystallites having chemistry consistent with members of the

pyroxene group of minerals with the chemistries (Ca,Na,Mg,Fe²⁺,Mn,Fe³⁺,Al,Ti)₂

[(Si₅Al)₂O₆] and (Mg₅Fe²⁺Ca)(Mg₅Fe²⁺)[Si₂O₆].

Claim 26 - The composition of Claim 20 wherein said plurality of newly- formed

crystalline phases comprises crystallites having equant blocky morphological

characteristics with chemistry consistent with members of the pyroxene group of

minerals with the chemistries (Ca,Na,Mg,Fe²⁺,Mn,Fe³⁺,Al,Ti)₂ [(Si₅Al)₂O₆] and

(Mg₅Fe²⁺Ca)(Mg₅Fe²⁺)[Si₂O₆].

Claim 27 - A composition comprising, in combination, a fused mixture having:

quartz and remnant ash mineral and mineraloid grains; a glass phase; and

a plurality of newly-formed crystalline phases,

wherein said plurality of newly-formed crystalline phases comprise

crystallites dispersed in said glass phase.

Claim 28 - The composition of Claim 27 wherein said glass phase is heterogeneous and

comprises, in combination, aluminum, silicon, and lesser amounts of cations.

Claim 29 - The composition of Claim 27 wherein said plurality of newly-formed

crystalline phases comprises crystallites with chemistry consistent with the chemistry

(Ca[SiO₃]).

Claim 30 — The composition of Claim 27 wherein said plurality of newly-formed

crystalline phases comprises lath-shaped, plagioclase feldspar crystallites.

Claim 31 - The composition of Claim 27 wherein said plurality of newly-formed

crystalline phases comprises pyroxene crystallites.

Claim 32 - The composition of Claim 27 wherein said plurality of newly-formed

crystalline phases comprises crystallites having the chemistry (CaSO₄).

Claim 33 - A composition comprising, in combination, a fused mixture having:

quartz and ash remnant mineral and mineraloid grains;

a glass phase; and

a plurality of newly-formed crystalline phases,

wherein said plurality of newly-formed crystalline phases comprises

crystallites having the chemistry (Ca[SiO₃]), lath-shaped plagioclase feldspar crystallites, pyroxene crystallites, and crystallites having the

chemistry (CaSO₄).

Claim 34 - A hybrid rock formed by the process of:

reclaiming waste material selected from the group consisting of mine

tailings, fly ash, bottom ash, slag, quarry fines, or slimes; and

subjecting the waste materials to pressure; and

subjecting the waste materials to heat;

whereby the waste materials convert to a hybrid rock characterized

by water absorption less than 7%.

Claim 35 - The hybrid rock of Claim 34 wherein said hybrid rock is characterized by

water absorption less than 4%.

Claim 36 - The hybrid rock of Claim 34 wherein said hybrid rock is characterized by

water absorption less than 1%.

Claim 37 - The hybrid rock of Claim 34 wherein said hybrid rock is characterized by

water absorption less than 0.5%.

Claim 38 — The process of Claim 34 wherein the waste material is delivered to a

screening apparatus to separate undersized and oversized tailings particles from the mine

tailings to be processed.

Claim 39 - The process of Claim 38 wherein after screening, the waste material is

conveyed to a heated rotating chamber.

Claim 40 - The process of Claim 39 wherein the waste material in said heated rotating

chamber undergoes chemical transformation. Claim 41 - The process of Claim 40 wherein said chemical transformation of the waste

material comprises drying, preheating, combustion, dehydration, desulphurization,

decomposition and the like.

Claim 42 - The process of Claim 40 wherein the waste material exits said heated rotating

chamber and passes through a valve before entering a second heated chamber.

Claim 43 - The process of Claim 42 wherein said valve is rotary and capable of

continuously passing the waste material while simultaneously maintaining a pressure

gradient.

Claim 44 - The process of Claim 42 wherein a vacuum is applied to the waste material in

said second heated chamber.

Claim 45 — The process of Claim 42 wherein the waste material exits said second heated

chamber and are conveyed forward into a third heated chamber positioned within a

heating element.

Claim 46 - The process of Claim 45 wherein pressure is applied to the waste material in

said third heated chamber for a predetermined amount if time.

Claim 47 - The process of Claim 46 wherein said hybrid rock passes through a die device

and is removed from said third heated chamber for subsequent use, or alternatively

forwarded to terminal heated chambers for further modification.

Claim 48 - A process for converting waste material selected from the group consisting of

mine tailings, fly ash, bottom ash, slag, quarry fines, or slimes into a hybrid rock

characterized by water absorption less than 7%, the steps including:

pressurizing the mine tailings; heating the mine tailings; and

forming a useful article of manufacture while deformable.

Claim 49 — The process of Claim 48 wherein the waste material is heated and pressurized

( within a heated chamber at an optimized temperature with an optimized amount of

pressure over an optimized period of time.

Claim 50 - The process of Claim 49 wherein the waste material is heated and pressurized

within said heated chamber at a temperature of approximately 1130 degrees C over a time

period of approximately 60 hours.

Claim 51 - The process of Claim 49 wherein during heating the waste material is

pressurized at a pressure of approximately 350 psi.

Claim 52 - The process of Claim 49 wherein the waste material is cooled at an

approximate rate of 1 to 3 degrees per minute.

Claim 53 - The process of Claim 49 wherein the waste material is heated and pressurized

within said heated chamber at a temperature of approximately 1140 degrees C over a time

period of approximately 6 hours.

Claim 54 - The process of Claim 53 wherein during heating the waste material is

pressurized at a pressure of approximately 300 psi.

Claim 55 - The process of Claim 53 wherein the waste material is cooled at an

approximate rate of 10 to 20 degrees per minute.

Claim 56 — The process of Claim 49 wherein the waste material is heated and pressurized

within said heated chamber at a temperature of approximately 1160 degrees C over a time

period of approximately 60 minutes. Claim 57 - The process of Claim 56 wherein during heating the waste material is

pressurized at an oscillating pressure between approximately 30 psi and 160 psi.

Claim 58 - The process of Claim 56 wherein the waste material is cooled at a rate of

approximately 5 to 15 degrees C per minute.

Claim 59 - The process of Claim 57 wherein the waste material is subjected to said

oscillating pressure in a partial vacuum environment.

Claim 60 — The process of Claim 49 wherein the waste material is heated and pressurized

within said heated chamber at a temperature of approximately 1115 degrees C over a time

period of approximately 10 hours.

Claim 61 - The process of Claim 60 wherein during heating the waste material is

pressurized at a pressure of approximately 300 psi.

Claim 62 - The process of Claim 60 wherein the waste material is cooled at a rate of

approximately 10 to 20 degrees C per minute.

Claim 63 - The process of Claim 49 wherein said hybrid rock is extruded through a die to

consolidate said hybrid rock, thereby forming a useful article of manufacture.

Claim 64 — A hybrid rock characterized by its primary constituent component of mine

tailings modified to exhibit lower water absorption by virtue of a glass matrix within

which crystallites are distributed.

Claim 65 — A hybrid rock characterized by its primary constituent component of mine

tailings, or silicate waste materials selected from the group consisting of mine

development rock, fly ash, bottom ash, slag, quarry fines, or slimes; said hybrid rock being formed by reclaiming the mine tailings or the silicate waste

materials, and subjecting the mine tailings or silicate waste materials to pressure,

and subjecting the mine tailings or silicate waste materials to heat, to exhibit low

water absorption.

Claim 66 - A hybrid rock characterized by a partially dissolved grain phase comprising,

in combination:

remnant mine tailings;

a glass phase; and

a crystalline phase distributed in said glass phase,

whereby said hybrid rock exhibits low water absorption.

Claim 67 - A hybrid rock characterized by its constituent component of mine tailings or

silicate waste materials selected from the group consisting of mine development rock, fly

ash, bottom ash, slag, quarry fines, or slimes;

a glass phase; and

at least one crystalline phase distributed in said glass phase,

said hybrid rock being formed by reclaiming the mine tailings or the silicate

waste materials, and subjecting the mine tailings or silicate waste materials to

pressure, and subjecting the mine tailings or silicate waste materials to heat, to exhibit

low water absorption. Claim 68 - An apparatus for forming hybrid rock, comprising in combination:

a means for preheating silicate waste materials selected from the group consisting of

mine tailings, mine development rock, fly ash, bottom ash, slag, quarry fines, or slimes; a

means for feeding silicate waste materials into a heated chamber; a means for heating

said heated chamber; and a means for delivering plastic hybrid rock from an exit of said

heated chamber.

Claim 69 — The apparatus of Claim 68 wherein said means for preheating silicate waste

materials comprises a heated rotating chamber maintained at an optimal temperature to

preheat and dry the silicate waste materials without melting the silicate waste materials.

Claim 70 — The apparatus of Claim 69 wherein said heated rotating chamber is situated at

an optimized angle to facilitate driving the silicate waste materials toward a discharge

assembly.

Claim 71 — The apparatus of Claim 69 wherein said heated rotating chamber is optionally

fixed with a gas inlet and vent for the respective entry and removal of air, gases, and the

like.

Claim 72 - The apparatus of Claim 69 wherein said optimal temperature of said heated

rotating chamber is approximately 800 to 1000 degrees C.

Claim 73 - The apparatus of Claim 68 wherein said means for feeding silicate waste

materials into said heated chamber comprises a dual capacity press assembly driven by

axial or rotational force.

Claim 74 — The apparatus of Claim 73 wherein said press assembly is powered by

hydraulic force. Claim 75 — The apparatus of Claim 68 wherein said means for heating said heated

chamber comprises mounting said heated chamber in a heating element substantially

surrounding said heated chamber.

Claim 76 - The apparatus of Claim 75 wherein said heating element comprises a split-

tube design and is constructed with multiple temperature zones throughout.

Claim 77 — The apparatus of Claim 75 wherein said heating element provides heat by

electrical resistance heaters, gas combustion, and the like.

Claim 78 - The apparatus of Claim 68 wherein said means for delivering plastic hybrid

rock from an exit of said heated chamber comprises a pressure resistance device to

consolidate said plastic hybrid rock material; and a die device with an aperture allowing

said plastic hybrid rock material to pass through.

/ / /