Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3450257 A
Publication typeGrant
Publication dateJun 17, 1969
Filing dateNov 15, 1967
Priority dateMar 2, 1964
Publication numberUS 3450257 A, US 3450257A, US-A-3450257, US3450257 A, US3450257A
InventorsEdwin Kenneth Cundy
Original AssigneeEnglish Clays Lovering Pochin
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Processing of clay
US 3450257 A
Abstract  available in
Images(2)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent US. Cl. 209 4 Claims ABSTRACT OF THE DISCLOSURE A method of removing titanium mineral impurities from a clay containing at least 40% by weight of particles smaller than 2 microns equivalent spherical diameter which comprises conditioning the clay at a solids content of at least 30% by weight for a time suflicient to dissipate therein at least 25 horsepower hours of energy per ton of solids and thereafter subjecting the clay to a froth flotation process in the presence of an activator consisting of a water-soluble salt of an alkaline earth metal or a heavy metal.

BACKGROUND OF THE INVENTION This is a continuatiou-in-part of application Ser. No. 435,340 filed Feb. 25, 1965 and now abandoned.

This invention relates to the processing of clays, of which kaolin and china clay are examples, containing at least 40% by Weight of particles smaller than 2 microns equivalent spherical diameter, and is more particularly concerned with a method of treating such clays to improve the brightness thereof by removing titanium mineral impurities therefrom.

Titanium mineral impurities occur in some clays as mined and, if they are colored, they detract from the appearance of the clay. It has previously been proposed to remove impurities by forming a suspension, or slurry, raising the pH of the slurry of the clay to an alkaline value, for example by the addition of ammonium hydroxide, and subjecting the slurry to a froth flotation process. In general the froth flotation process comprises adding a collector, for example oleic acid, to the alkaline slurry of the clay, conditioning the slurry by agitating the slurry in a tank for a time suflicient to dissipate therein about 5 to horsepower hours of energy per ton of solids, adding a frothing agent, for example pine oil, to the conditioned slurry, and then passing air through the slurry in a known manner in a froth flotation cell to effect separation of the impurities from the clay. However, many clays naturally contain a high proportion, i.e. greater than 40% by weight, of particles of extremely small dimensions, i.e. two microns equivalent spherical diameter or smaller, and these clays are therefore natural slirnes; such particles are difficult to separate by a simple froth flotation process of the type described above. The individual, extremely small particles of the clay are grouped together into large masses and are loosely bound by inter-particulate forces i.e. they are flocculated. Such masses may have impurities included and held therein and these impurities, which are bound in the larger masses, are not therefore capable of being separated by a simple froth flotation process. In fact, in many industrial froth flotation processes, all the material consisting of particles smaller than 50 microns is separated from the crude ore and discarded. In order to try to overcome this problem it has been proposed to deflocculate the clay before treating the same by a froth flotation process. To effect the deflocculation, it has been proposed to add, for example, sodium silicate to the clay slurry before the addition of the ammonium hydroxide.

It has also been proposed to add an activator to the slurry before carrying out the froth flotation process, see for example United States Patent No. 2,894,628 in which it is proposed that the froth flotation process described above should be carried out in the presence of an activator selected from ammonium, potassium and magnesium sulphates. However, all of these \known processes only work efficiently with coarse clays, i.e. clays containing not more than by weight of particles smaller than 2 microns, and do not work efficiently with clays containing a high proportion, i.e. greater than 40% by weight, of particles smaller than 2 microns equivalent spherical diameter.

SUMMARY OF Til-IE INVE'N'IIION I have now discovered that the difliculties which arise when attempting to refine by a froth flotation process clays containing more than 40% by Weight of particles smaller than 2 microns equivalent spherical diameter are, to a large extent, due tosurface contamination of the particles which reduces the effective difference between two different mineral particles. To overcome these difliculties I propose, in accordance with the present invention, to subject the particles toa thorough scrubbing prior to carrying out the froth flotation process and to carry out the froth flotation process in the presence of an activator which is a Water-soluble salt of an alkaline earth metal or a heavy metal. More particularly, according to the present invention there is provided a method of treating a clay containing at least 40% by Weight of particles smaller than 2 microns equivalent spherical diameter in order to separate therefrom titanium mineral impurities, which method comprises the steps of:

'(a) Mixing the clay in the form of an aqueous slurry having a solids content of at least 30% by weight with an alkali to raise the pH of said aqueous slurry to an alkaline value, a deflocculant, a collector for the titanium mineral impurities, and an activator consisting of a water-soluble salt of a metal chosen from the alkaline earth metals and the heavy metals;

'(b) Conditioning the clay slurry at said solids content of at least 30% by Weight for a time suflicient to dissipate therein at least 25 horsepower hours of energy per ton of solids;

(c) Adding to the conditioned clay slurry a frothing agent; and

((1) Introducing the conditioned clay slurry containing the frothing agent into a froth flotation cell and subjecting the conditioned clay slurry to a froth flotation process.

Herein the term alkaline earth metals is to be understood to include magnesium, and the term heavy metals refers to metals having a specific gravity which is greater than 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS To accomplish the thorough scrubbing of the particles before carrying out the froth flotation process, it is essential that the conditioning of the clay slurry be carried out before the frothing agent is added thereto and at a solids content of at least 30% by weight. However, it is preferred that the solids content of the aqueous clay slurry be in the range of from 40% to 60% by weight.

The activator, which is a water-soluble salt of an alkaline earth metal or a heavy metal, is advantageously a water-soluble salt of barium, calcium, cupric copper, ferrous iron, plumbous lead, magnesium, manganous manganese, strontium or zinc. Examples of suitable salts are lead acetate, lead nitrate, barium chloride and calcium chloride. The amount of activator employed is generally in the range of from 0.2 to 2.0 lbs. per ton of solids in the clay slurry.

The alkali used for raising the pH of the slurry to an alkaline value can be ammonium hydroxide although it will be appreciated that other similar materials may alternatively be used.

The deflocculant can be, for example, sodium silicate.

The collector for the titanium mineral impurities can be, for example, oleic acid, and the frothing agent can be, for example, pine oil.

After the clay slurry has been conditioned and before it is treated inthe froth flotation cell it is advantageously diluted with water to a solids content of from 15 to 20% by weight.

The whole of the necessary quantities of the activator and of the collector are not necessarily added to the aqueous slurry of the clay before the beginning of the froth flotation process. Indeed, it has been found advantageous to add about one half the required quantity of each of these reagents prior to initiating the froth flotation process; and, thereafter, during the froth flotation process, to add further, smaller quantities of collector and activator, there preferably being a period of conditioning of the aqueous slurry of the clay after each further addition of reagent.

In order that the invention may be more clearly understood and readily carried into effect, reference will now be made to the following example.

Example In this example, a sample of kaolin from Georgia, United States of America, was employed. The chosen sample contained 45% by weight of particles smaller than 2 microns equivalent spherical diameter and showed a relatively high coloration. The clay was formed into an aqueous slurry having a solids content of 40% by weight. Sodium silicate was then added to the suspension in the amount of approximately 4 lbs. of silicate per ton of clay in order to deflocculate the clay. The slurry was then partially conditioned by agitation for 6 minutes with a high-speed stirrer. After the agitation, lead acetate, as activator, was added in the amount of 1.25 pounds per ton of clay, followed by 10% ammonium hydroxide solution in the amount of 2 pounds per ton and oleic acid in the amount of 3 pounds per ton of clay. The resulting clay slurry was further conditioned for a period of 6 minutes with the high-speed stirrer. The use of the high-speed stirrer and the total conditioning time of 12 minutes at the high solids content means that there was dissipated in the clay slurry about 30 horsepower hours of energy per ton of solids. After being conditioned, the clay slurry was diluted to form a slurry having a solids content of 16%. The resulting diluted slurry was treated in a froth flotation cell after the addition of pine oil as a frothing agent. At intervals of 20 to 25 minutes, further quantities of lead acetate and oleic acid were added at from A to A2 of the original amount, each addition being followed by a conditioning period before restarting the froth flotation process. The total time of the froth flotation process was about 100 minutes.

The total consumption of reagents per ton of clay was as follows:

Lbs. Oleic acid 6.75 Ammonium hydroxide 2 Lead acetate 2.5 Sodium silicate 4 To determine the degree of purification of the clay, brightness values were measured both for the original clay and for the product of the process just described. The brightness of the clay was determined by measuring the percentage reflectance of violet light having a wave length of 458 millimicrons. The results of the tests are given in the table below. The clay treated by the process just described will for brevity be referred to as Clay A.

For comparison purposes, two separate samples of clay were processed by known methods. The first sample was formed into a slurry, conditioned for a time sufficient to dissipate therein about 10 horsepower hours of energy per ton of solids and treated with ammonium hydroxide to raise the pH level to pH 9; a froth flotation process was then carried out in known manner, using oleic acid as a collector and pine oil as a frothing agent. The clay treated by this method is referred to as Clay B in the table below. The second sample of comparison clay, Clay C, was treated in the same way as was Clay B except that sodium silicate was added before alkalination to ensure substantially complete deflocculation of the clay in the suspension.

I claim:

1. A method of treating a clay to remove therefrom titanium mineral impurities, said method comprising the steps of:

(a) mixing a clay containing at least 40% by weight of particles smaller than 2 microns equivalent spherical diameter in the form of an aqueous slurry having a solids content of clay of at least 30% by weight with an alkali to raise the pH of said aqueous clay slurry to an alkaline value, a deflocculant, a collector for the titanium mineral impurities, and an activator consisting of a water-soluble salt of a metal chosen from the alkaline earth metals and the heavy metals;

(b) conditioning the aqueous clay slurry at said solids content of at least 30% by weight for a time suflicient to dissipate therein at least 25 horsepower hours of energy per ton of solids;

(0) adding to the conditioned aqueous clay slurry a frothing agent; and

(d) introducing the conditioned aqueous clay slurry containing the frothing agent into a froth flotation cell and subjecting the conditioned aqueous clay slurry to a froth flotation process.

2. A method according to claim 1, wherein the aqueous clay slurry is conditioned at a solids content of clay of from 40% to 60% by weight.

3. A method according to claim 2, wherein the conditioned aqueous clay slurry is diluted to a solids content of clay of from 15% to 20% by weight before it is subjected to a froth flotation process.

4. A method according to claim 1 wherein the heavy metal has a specific gravity greater than 4.

References Cited UNITED STATES PATENTS 1,029,579 6/ 1912 Schwerm 209-5 2,105,826 1/1938 Tartaron 209-166 2,249,569 7/1941 Phelps 209-166 2,249,570 7/ 1941 Lane 209-166 2,569,680 10/1951 Leek 209-10 2,661,842 12/1953 Duke 209-166 2,861,687 11/ 1958 Lord 209-167 2,894,628 7/ 1959 Duke 209-166 3,164,549 1/1965 Seymour 209-166 2,990,958 7/1961 Greene 209-166 3,224,582 12/1965 Iannicelli 209-166 3,337,048 8/1967 Mercade 209-5 3,353,668 11/1967 Duke 209-166 X HARRY B. THORNTON, Primary Examiner.

ROBERT HALPER, Assistant Examiner.

US. Cl. X.R. 209-166

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1029579 *Aug 29, 1911Jun 11, 1912Botho SchwerinMethod of separating substances in suspension by washing.
US2105826 *Oct 18, 1935Jan 18, 1938Phosphate Recovery CorpConcentration of nonmetallic minerals
US2249569 *Jul 29, 1940Jul 15, 1941Edgar Brothers CompanyTreatment of clay by flotation
US2249570 *Jul 29, 1940Jul 15, 1941Edgar Brothers CompanyFractionation of clay
US2569680 *Feb 4, 1949Oct 2, 1951Edgar Brothers CompanyFlotation process for whitening clay
US2661842 *Aug 3, 1950Dec 8, 1953Attapulgus Minerals & ChemicalConcentration of phosphate ores
US2861687 *Sep 9, 1955Nov 25, 1958Southwestern Eng CoFlotation of heavy metal oxides
US2894628 *Jul 13, 1956Jul 14, 1959Minerals & Chemicals Corp Of AClay brightness by flotation
US2990958 *Dec 9, 1958Jul 4, 1961Minerals & Chem Philipp CorpFroth flotation method
US3164549 *Jul 31, 1961Jan 5, 1965Armour & CoFlotation separation of phosphate ores
US3224582 *Jun 1, 1965Dec 21, 1965Huber Corp J MKaolin clay beneficiation
US3337048 *Dec 2, 1964Aug 22, 1967Minerals & Chem Philipp CorpMethod for beneficiating clay by flotation
US3353668 *Dec 16, 1963Nov 21, 1967Mineral & Chemicals Philipp CoMethod for improving the brightness of clay
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3770213 *Jan 18, 1972Nov 6, 1973Bethlehem Steel CorpProcess for separating carbon from iron-bearing fines in blast furnace flue dusts
US3915391 *Aug 29, 1974Oct 28, 1975Engelhard Min & ChemRecovery of scheelite from ores by flotation
US3919079 *Mar 7, 1973Nov 11, 1975Weston DavidFlotation of sulphide minerals from sulphide bearing ore
US3964997 *Sep 26, 1974Jun 22, 1976David WestonConcentration of gold, sulphide minerals and uranium oxide minerals by flotation from ores and metallurgical plant products
US3974067 *Oct 8, 1974Aug 10, 1976Anglo-American Clays CorporationMethod for improving clay brightness utilizing magnetic separation
US3979282 *Jan 16, 1975Sep 7, 1976English Clays Lovering Pochin & Company LimitedFlotation of fine-grained materials
US4014709 *Jun 8, 1976Mar 29, 1977Engelhard Minerals & Chemicals CorporationOpacifying pigments and methods for making same
US4097372 *Jul 8, 1976Jun 27, 1978Anglo-American Clays CorporationMethod for improving clay brightness utilizing magnetic separation
US4098688 *Jul 21, 1976Jul 4, 1978Anglo-American Clays CorporationBrightening of clay by froth flotation
US4492628 *Aug 25, 1982Jan 8, 1985Freeport Kaolin CompanyMethod of treating clay to improve its whiteness
US4501658 *Aug 25, 1982Feb 26, 1985Freeport Kaolin CompanyMethod of conditioning clay for flotation using in situ ferrous activator
US4514288 *Oct 13, 1983Apr 30, 1985Mobil Oil CorporationOre beneficiation process
US4629556 *Nov 29, 1984Dec 16, 1986Thiele Kaolin CompanyPurification of kaolin clay by froth flotation using hydroxamate collectors
US4997550 *Nov 13, 1989Mar 5, 1991Ecc America Inc.Method for improved flotation of discoloring impurities from kaolinite
US5037534 *Sep 14, 1989Aug 6, 1991J. M. Huber CorporationFlotation aid and process for removal of impurities from silicate minerals
US5137574 *Nov 30, 1990Aug 11, 1992Ecc America Inc.Method for producing high opacifying kaolin pigment
US5180511 *Jun 20, 1991Jan 19, 1993J.M. Huber CorporationFlotation aid and process for removal of impurities from silicate minerals
US5213687 *Jan 22, 1992May 25, 1993Ecc International Inc.Apparatus for filtering mineral slurries
US5223155 *Jan 22, 1992Jun 29, 1993Ecc International Inc.Method for filtering mineral slurries
US5332493 *Apr 28, 1992Jul 26, 1994Ecc International Inc.Method for improving rheological properties of kaolin clays
US5371051 *Dec 23, 1993Dec 6, 1994Ecc International Inc.Method for producing high opacifying kaolin pigment
US5454865 *Dec 23, 1993Oct 3, 1995Ecc International Inc.Method for preparing refined kaolin in clay products
US5522924 *Mar 17, 1995Jun 4, 1996Ecc International Inc.Method for producing high brightness low abrasion calcined kaolin pigment
US5522986 *Mar 3, 1995Jun 4, 1996Thiele Kaolin CompanyProcess for removing impurities from kaolin clays
US5545338 *Jan 19, 1993Aug 13, 1996Ecc International Inc.Method for filtering mineral slurries
US5547574 *Jan 19, 1993Aug 20, 1996Ecc International Inc.Apparatus for filtering mineral slurries
US5685899 *Jul 28, 1995Nov 11, 1997Thiele Kaolin CompanyProcess for conditioning kaolin clays prior to removing impurities
US5810998 *Jun 5, 1997Sep 22, 1998Thiele Kaolin CompanyProcess for improving the brightness of fine-grained kaolin clays
US5891326 *Dec 8, 1997Apr 6, 1999Thiele Kaolin CompanyProcess for removing impurities from kaolin clays
US6007618 *Nov 10, 1997Dec 28, 1999Thiele Kaolin CompanyKaolin clays which are conditioned prior to removing impurities
US6186335Mar 20, 1998Feb 13, 2001Thiele Kaolin CompanyProcess for beneficiating kaolin clays
US6200377Apr 16, 1999Mar 13, 2001Thiele Kaolin CompanyProcess for beneficiation of mixtures of mineral particles
US6390301Jul 18, 2000May 21, 2002Cytec Industries Inc.Process for removing impurities from kaolin clays
US7393462May 13, 2004Jul 1, 2008Cytec Technology Corp.Process and reagent for separating finely divided titaniferrous impurities from Kaolin
US7648032Mar 22, 2005Jan 19, 2010Imerys Pigments, Inc.Effective reductive bleaching of mineral slurries
US7727324Apr 28, 2005Jun 1, 2010Imerys Pigments, Inc.Compositions comprising kaolin having nanosize dimensions
US7780779Feb 8, 2006Aug 24, 2010Imerys Pigments, Inc.Method for separating mixture of finely divided minerals
US7806978Dec 15, 2003Oct 5, 2010Imerys Pigments, Inc.Fine platy kaolin composition
US8016936May 2, 2005Sep 13, 2011Imerys Pigments, Inc.Methods of calcining particulate material
US8083848Feb 8, 2006Dec 27, 2011Imerys Pigments, Inc.Compositions comprising fine sedimentary kaolin and methods for preparing same
US8465583Dec 21, 2011Jun 18, 2013Imerys Pigments, Inc.Compositions comprising fine sedimentary kaolin and methods for preparing same
CN102060303A *Dec 3, 2010May 18, 2011孝义市天章铝业有限公司Method for preparing artificial mullite raw material by bauxite
EP0104099A2 *Aug 5, 1983Mar 28, 1984Engelhard CorporationMethod for froth flotation
EP0104100A2 *Aug 5, 1983Mar 28, 1984Engelhard CorporationMethod of treating clay in order to remove mineral titanium-based impurities
EP1686104A1Jan 31, 2006Aug 2, 2006Companhia Vale Do Rio DoceA method for processing fine kaolin
WO1992009662A1 *Nov 26, 1991Jun 11, 1992Ecc America IncMethod for producing high opacifying kaolin pigment
WO1996027444A1 *Mar 1, 1996Sep 12, 1996Thiele Kaolin CoProcess for removing impurities from kaolin clays
WO2004085336A2Mar 16, 2004Oct 7, 2004Imerys Kaolin IncUnusually narrow particle size distribution calcined kaolins
WO2005113687A1Apr 27, 2005Dec 1, 2005Cytec Tech CorpProcess and reagent for separating finely divided titaniferrous impurities from kaolin
Classifications
U.S. Classification209/5, 209/166, 209/901
International ClassificationB03D1/06, B03D1/001, C04B33/10
Cooperative ClassificationB03D1/06, Y10S209/901, C04B33/06, C04B33/30, C04B33/10, B03D1/001
European ClassificationC04B33/30, C04B33/10, C04B33/06, B03D1/001, B03D1/06