US 3507644 A
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United States Patent 3,507,644 TITANIUM ADDITIVE AND METHOD OF USE THEREOF John D. Coyle, Chicago, Ill., assignor to Miller & Company, Chicago, 11]., a corporation of Illinois No Drawing. Filed Apr. 4, 1966, Ser. No. 539,740 Int. Cl. C22c 33/02, 37/00, 37/04 US. Cl. 75130 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to the production f gray iron, and specifically to a titanium additive therefor and methods of making and using the additive.
Titanium is generally recognized as a desirable addition to gray iron, particularly because of its tendency to reduce pin holes and gas holes in iron castings. Specifically, it removes nitrogen and oxygen and thereby tends to reduce, if not substantially eliminate, pin hOles and gas holes. Titanium is considered to be a potent graphitizer in that it causes the flake graphite to precipitate in a better distribution pattern. Titanium acts as a scavenger for nitro gen and tends to eliminate pin holes in iron castings since an inert titanium nitride is precipitated which is generally recognized as a harmless inclusion. Titanium further promotes the formation of a finer grain structure, sounder castings, and improves physical properties, particularly strength and machinability. It is likewise generally recognized that small quantities of titanium decrease the chilling tendency.
Titanium in pure or relatively concentrated alloy form is not normally added to the cupola because of inconsistent final analyses at the cupola spout. Possibly titanium in such forms is readily oxidized by the cupola blast, but it appears more likely that the primary reason for erratic recoveries is that small additions of such materials as ferro titanium sift down in a vertical shaft furnace and do not remain as a component of the original charge. Ladle additions of titanium must be rather carefully controlled or again recoveries may be low or erratic.
Accordingly a primary object of the invention is to provide a titanium additive which can be incorporated into conventional iron foundry practices with little or no modification of, or addition to, either the existing foundry equipment or the conventional foundry practice.
Another object is to provide an additive as above described which utilizes titanium in a convenient material form and which can be associated with other addition materials such as silicon carbide, ferro silicon, ferro manganese, ferro chrome and combination thereof, said other addition materials thereby performing the additional function of a carrying agent.
Yet another object is to provide a titanium additive in such a form that high recoveries and uniform results will be consistently achievable.
Yet another object is to provide a titanium additive which can, without modification, be used in all the conventional melting units currently employed in foundries, but is especially well adapted for cupola practice.
Yet a further object is to provide a method of making the above described titanium additive material.
3,507,644 Patented Apr. 21, 1970 Yet a further object is to provide a method of making iron or other metallic componds in which titanium is a desired element.
Other objects and advantages will become apparent from a reading of the following description of the invention.
At the present time silicon carbide in granular or briquetted form is widely used in the production of gray ifon, ductile iron, and malleable iron because it is an excellent deoxidizer and degasser. It may be made into conveniently sized briquettes which are used during the melting and pouring process. In the cupola, for example, silicon car. bide briquettes are charged on top of each coke split and descend through the stack of the cupola with each charge. At the melting zone the briquettes contact the molten metal and slag. After the silicon carbide dissolves into molten iron it disassociates and becomes chemically reactive. In electric and air furnace practice the silicon carbide briquettes may be charged on the bottom of the furnace or added to the top of the molten metal bath. At the present time conventional silicon carbide briquettes are available with varying silicon carbide contents, two readily available types containing, respectively, 65% and silicon carbide. Such briquettes function as a deoxidizer and a source of silicon.
My invention includes the concept of associating a titanium containing material with a carrying element, such as silicon carbide, and adding the resultant product to the charge to be melted in the melting unit. In this Way the titanium is brought into intimate contact with the molten metal and oxidation losses resulting from the cupola blast Will substantially, if not largely, be eliminated. As a result the titanium recovery will be high and consistent, and the desirable advantages heretofore mentioned will be achieved. A detailed description of several embodiments of my invention follow.
For purposes of illustration it will be assumed that the titanium will be added to the cupola. It should be understood that it is quite within the scope of the invention to add the titanium by substanially the same means to other types of melting units such as the electric or reverberatory furnace.
Titanium containing material in several forms may be used as a starting material, among which are ferro titanium, titanium slag, ilmenite and rutile ores.
-A high carbon ferro titanium Will contain approximately fifteen to eighteen percent titanium and from six to eight percent carbon. The cost of ferro titanium is relatively high, however.
As an alternative, titanium bearing slag may be employed, said slag being available from the Quebec Iron & Titanium Corp. of Sorel, Canada. The slag is derived from ilmenite ore which contains about 35% TiO The slag contains about 70% TiO Listed below is a typical analysis of the above described titanium slag:
TiO 7O% average content FeO-l2-15 Fe1.5 max. usually .7 to .8 metallic Fe SiO -3.55
CaO-1.2 max. usually .8 Cr O --.25 max. usually .18 V O .5.6
P O -.025 max. usually .015
Note: Ti O -l0-15% included in above content of TiO Preferably, however, a titanium bearing material in a form suitable for association with a carrying element is employed. Said materials may take any of several forms and may be described generally as titanium residues. It might for example be a titanium chip material such as would be produced from titanium machining operations. Or the titanium containing material may be the product of a chemical process which resulted in a titanium slime. In the latter event the material will preferably be further processed into a dry form suitable for bulk handling.
From the above it will be noted that the titanium bearing material may take many forms and may have a widely varying titanium content. As a specific example, a material known as TICO 90 may be employed. This material is available from Frankel and Co. Inc. of Detroit, Michigan. A typical analysis of TICO 90 follows:
Percent Titanium r 89 Aluminum 3 /2 Iron Balance The TICO 90 is preferably sized to about 20 mesh by down and then mixed in the desired proportions with a suitable carrying agent which preferably is another additive material used in the iron making process. Silicon carbide, ferro silicon, ferro chrome and ferro manganese or combinations thereof may be employed. Preferably the sized titanium containing material is mixed with silicon carbide which has been sized in a conventional manner to a conventional standard.
It will be understood that the relative proportions of the titanium containing material and carrying agent may be varied depending upon the titanium content of the titanium containing material, and the eventual recovery desired in the iron. Since TICO 90 contains about five times as much titanium as does ferro titanium, only onefifth as much TICO 90 need be employed for the same desired eventual titanium content of the iron as would be required if ferro titanium were used.
A suitable binder is then normally added to the mixture of silicon carbide and titanium containing material. One satisfactory binder is portland cement. Preferably a high early strength cement, which is also known as Type III cement (described by ASTM-l5063) is employed. This binder contains, as its primary constituents, the following materials, which are set out as a representative analysis.
Percent Tricalcium silicate 60 Dicalcium silicate 13 Tricalcium aluminate 9 Tetracalcium aluminoferrite 8 Magnesia, max Calcium sulphate, max 4 Ignition loss 1 Insoluble residue, max
For a more complete description reference is made to the aforementioned ASTM specification.
Suflicient water is then added to the mixture to effect complete hydration of the cement. The amount of water added will depend to some extent upon the following process steps, which will next be described.
Under some circumstances the use of a binder may be omitted. If titanium containing material is used in in a form which is inherently packable, such as shavings or turnings or chips, the silicon carbide or other carrying element and the titanium material may be formed into a desired shape by means which does not require a binder. Under some circumstances the titanium containing material and the carrying element may merely be deposited in self-sustaining containers, such as cans, or non-self-sustaining containers. The container should of course be composed of a material which is either compatible with the melting unit charge, such as low carbon steel, or which will not deleteriously affect it. When the container method is used the titanium containing material and the carrying element are preferably in a granular, intermixed form.
After the titanium containing material, the agent, the binder (if employed) and the water (if employed) have been intimately mixed the mixture is then composed into a form suitable for convenient incorporation into the iron making process. Preferably, the mixture is briquetted.
At the present time briquettes are formed by placing the flowable mixture into a mold assembly having a stationary mold member and exerting a mechanically derived pressure sufficient to set up the material in the stationary mold cavity. The briquettes may even be formed by subjection to hydraulic pressures. If desired the mixture may be made into a slurry and poured into molds which may be of brick shape. The material is then merely air cured in the molds. Alternately the slurry material may be cured by heat or chemical processes. It may even be convenient to extrude the mixture, the extruded product being dried by exposure to air, chemicals or heat.
After the material has hardened to a self sustaining shape it may be pelletized and shipped directly to the cupola Where it is charged into the melting unit.
Two typical compositions for a briquette made by the first described procedure would be as follows:
Percent 5 8 75 75 Binder 8 8 Other (largely complex silicates) 12 9 Percent Titanium containing material 3-40 Carrying element 60-97 Binder material-Optional /2l2 If the metallic charge going into the cupola contains an insignificant amount of titanium the amount of titanium enriched silicon carbide briquettes to be added may be rather readily calculated knowing the recovery achievable. The recovery will vary from installation to installation depending on operating procedures peculiar to each installation, but a skilled foundryman will quickly be able to determine his recovery factor based on his specific equipment, procedure and experience. As the percentage of titanium containing returns increases, the amount of titanium enriched silicon carbide briquettes can be reduced. It is thereby feasible for the foundryman to carry only two types of silicon carbide briquettes, namely a conventional titanium free silicon carbide briquette, and a titanium enriched silicon carbide briquette. By suitably proportioning the amounts of each type of briquette to be used, and knowing the titanium content of the charge derived from the returns and the expected recovery, it is within the ability of a skilled foundryman to calculate the percentage of each type of briquette needed to achieve a final desired titanium content in the casting.
Optionally, the particles of titanium containing material and the carrying agent may be shrouded by a thin layer of coal tar, all as fully described in US. Patent 2,527,829. Shrouding or protecting the individual particles may, in some instances, ever further enhance the recovery of titanium.
It will be understood that the above description is exemplary only for it is apparent that one may depart from the specific examples Within the spirit and scope of the invention. Essentially my invention contemplates that a titanium containing material will be mixed in a relatively finely divided form with another additional material which is also in a relatively finely divided form, and the resultant product added to the iron making process at the same stage that the other additive material would have been added in the absence of titanium enrichment. By adding the titanium containing material to the charge in finely divided form during melting, high recoveries will be realized. Accordingly, it is my intention that the scope of my invention be limited not by the scope of the above description but solely by the hereafter appended claims.
1. A melting unit additive, said additive comprising a titanium containing material in heat reducible finely divided form selected from the group consisting of powder, shavings, turnings and chips physically intermixed with a. solid non-titanium additive material selected from the group consisting of silicon carbide, ferro silicon, ferro manganese, ferro chrome, and combinations thereof,
said mixture being formed into a coherent mass capable of being charged into a melting unit for nodularizing and physical property enhancement.
2. The melting unit additive of claim 1 further char acterized in that the titanium containing material is selected from the group consisting of titanium residues, ferro titanium, and titanium slag.
3. The melting unit additive of claim 2 further including a binder.
4. The melting unit additive of claim 3 further characterized in that the titanium containing material comprises about 3% to about 40%, by weight, of the additive.
5. The melting unit additive of claim 4 further characterized in that the binder comprises about /2% to about 12%, by Weight, of the additive.
6. The melting unit additive of claim 5 further characterized firstly, in that the titanium containing material has the following approximate composition:
Titanium-89 Aluminum-3 /2 Iron-Balance and the binder is portland cement.
7. The melting unit additive of claim 6 further characterized in that the non-titanium additive material comprises silicon carbide with incidental impurities.
8. The melting unit additive of claim 5 further characterized in that the additive is formed into briquettes. 9. In the process of making gray iron, the step of charging a melting unit additive comprising a titanium containing material in heat reducible, finely divided form selected from the group consisting of powder, shavings, turnings and chips which is physically intermixed with a solid non-titanium containing gray iron additive material selected from the group consisting essentially of silicon carbide, ferro silicon, ferro manganese, ferro chrome, and combinations thereof, and formed into a coherent mass, into the melting unit as a charge material for nodularizing and physical property enhancement.
10. The process of claim 9 further characterized in that the additive is charged into a cupola.
References Cited UNITED STATES PATENTS 1,397,404 11/1921 Coles 58 2,683,662 7/1954 Tisdale et al. 75123 2,805,145 9/1957 Henderson et a1. 7527 OTHER REFERENCES Cornstock, George F., Titanium in Iron and Steel. N.Y., John Wiley & Sons, Inc., 1955. pp. 20-29.
L. DEWAYNE RUTLEDGE, Primary Examiner J. E. LEGRU, Assistant Examiner US. Cl. X.R. 7558, 123, 129