US1114030A - Process of agglomerating fine ores. - Google Patents

Description

i To all whom it may concern:

PATENT OFFICE- JAMES H. PAY E, or Bntrnvionn, MaRLYLANn.

PROCESS OF AGGLOMERATI NG FINE OBES.

No Drawing.

i Specificationef Letters-Patent. .Pate t dflct 20 1914 Applieation filed April 10, 1913. Serial No. 760,260;

Be it known that I, JAMES I'IJPAYNE, a

citizen of the United States, residing at Baltimore, in the State of Maryland, have invented or discovered certain new and use ful Improvements in Processes of Agglonn erating Fine Ores, of which the following is a specification, reference being had therein to the accompanyingdrawings.

This invention relates to the treatment of fine ores and other comminuted metal bearing materials, such for example as fine dust and more particularly to the treat ment of materials of this character containing a relatively high proportion of sulfur,

for the purpose of. making the same available for use in the blast furnace or other reducing operations. finely divided or comminuted materials capable of commercial utilization it. is neces sary to convert the same into definite masses of appreciable size. This, in the case of iron and other metal bearing ores relatively low in sulfur, has been successfullyaccomplished by agglomeration or nodulization in accordance with a well known process described, for example, in the patents to Whitman, No. 978,971, Dec. 20, 1910; Dicke, No. 986,271, March 7, 1911; and King, .No. 995,542, June 20, 1911. In accordance with this process the finely divided material is introduced into the upper end of an inclined, rotating kiln or furnace to the lower end of which heat is applied, usually by means of a suitable oil or other vburner projectingfinto said lower end. The rotation of the kiln or furnace causes the material to travel downwardly therein, the heat first driving off the volatile matter in the material and finally, as such material approaches the lower end of the kiln, raising the temperature thereof to the point of incipient fusion, thus causing said material to becomesemi-plastic, so that, when agitated by rolling upon the interior of the rotating kiln, nodules, well adapted for further metallurgical operations, are produced and discharged from the lower end of the kiln. When, however, attempt is made to employ this process for the agglomeration of ores or materials containing a rel. atively high proportion of sulfur (by which is meant approximately 5% or over) such, for example, as sulfid ores of copper, certain difliculties are encountered. The process depends for its successful practice upon the In order to make such fact that the material to be agglomerated is raised merely to its sintering temperature, or to the point of incipient fusion, so as to become semi-plastic, in which condition it maybe readily rolled into nodules. If, however, the materialbe heated to a temperature considerably above this point, it will fuse completely, becoming too fluid to nod :ulize and adhering to the inner wall of the kiln. WVhen copper and other ores containing a considerable proportion of sulfur are subjected to heat, the sulfur is expelled and ignited, and the heat generated by the com temperature of the ore or othermaterial to a point considerably above that of incipient fusion, so that successful agglomeration cannot be effected. In order to overcome these difliculties and to permit the agglomeration of copper and other sulfur-bearing ores or materialsby means of the process above described, the present invention contemplates subjecting the material to be agglomerated to a treatment which will prevent the complete fusion thereof under the temperature generatedby the oxidization of the sulfur. Preferably this is accomplished by mixing with said material a substance which produces a-mixture, of which the melting point (that is the temperature at which inore melting would occur, than is required for proper nodulization) will lie above the temperature thus generated. The substance em ployed forthis purpose will depend upon the nature of the ore or material treated. The melting point of amaterial being at a minimum when said material is in a neutral condition, the substance added to raise the melting point of the mixture to be nodulized should be of a less nearly neutral character than that of the ore treated, being basic or acid according as the ore is of a basic or acid character. Thus, in operating upon a basic ore, lime or oxidof iron will preferably be -added, whereas in operating upon an acid 'ore, silica or a silicious material is preferably. mixed therewith. By so adding to the material, to be, agglomerated a substance bustion or oxidization thereof raises the which will cause the fusing point of the shaped flame at the lower end of the kiln, it

is found that the copper or other sulfur bearing ore may be successfully nodulized.

The admixture of the temperature raising material may be made prior to the introduction of the ore into the kiln or this material may be introduced into the kiln directly while the process is being carried on. In cases of ores or materials having a small proportion of sulfur, but suflicient tocause the difficulties above referred to, the latter course would preferably be followed. Thus the material to be agglomerated may first be introduced into the kiln in its natural condition, and the process carried on until the material begins to stick to the kiln wall, whereupon the introduction of a small quantity of lime or silica, as the case may be, into the kiln will cause the material at once to separate from the kiln walls and agglomerate.

lBy this method the amount of foreign material added maybe reduced to a minimum. In ordinary cases, however, as, for example, in treating sulfid copper ores which contain approximately 15% of sulfur, the silica or .lime is preferably added before the material is introduced into the kiln. Should accretions at any time begin to accumulate so as to hinder the proper working of the kiln, a quantity of material or mixture of an essentially higher melting point is fed in, either with or without stopping the supply of the material previously fed, the result being to remove the accretions already formed. In

this way the process may be carried on continuously, it being unnecessary to regulate carefully the proportions of the added material or temperature raising substance, a less or greater quantity being used according as the agglomeration is taking place properlyor not. The foregoing results may also be accomplished by adding to the ma terial a substance which contains an ingredient which, in addition to producing a mixture capable of withstanding the high temperature without too muclrmelting, will act as a retarder upon the effective application of the heat generated by the combustion of the sulfur, that is to say a substance capable of endothermic decomposition. A suitable material for this purpose is an alkaline earthsulfate, for exam ole, calcium sulfate, the breaking up of W ich is endothermic, and which leaves lime, which as above stated prevents too ready fusion of the ore. The oxidization of the sulfur, as above explained, develops a high heat exothermically, so that c the addition of a small quantity of calcium sulfate or other retarder having an endothermic action will arrest the fusion until the material has passed through the heat the use of metallic ores which possess the necessary acid, basic, or other characteristics.

Having thus described my invention, I claim:

1. The process of agglomerating comminuted material containing a relatively high proportion of sulfur which consists in mixing with said material a substance which will prevent the complete fusion of the mixture under the influence of the temperature generated by the oxidization of sulfur, applying sufiicient heat to said mixture to cause the same to become semi-plastic, and agitating the mass by rolling the same.

2. A process of agglomerating comminuted ores of an acid character, containing a relatively high proportion of sulfur, which comprises mixing with said ores a substance having a more strongly acid character than said ores, in amount sufficient to prevent over fusion, applying sufficient heat to said mixture to cause the same to become semiplastic, and while in said condition, causing the particles to agglomerate with each other.

3. The process of agglomerating fine sulfid ore of copper which consists in mixing with said ore a substance which raises the point of complete fusion of the mixture above the temperature generated by the oxidization of sulfur, applying sufiicient heat to said mixture to cause the same to become semi-plastic, and agitating the mass by rolling the same.

4. The process of aggloinerating comminuted material containing a relatively high proportion of sulfur which consists in mixing with said material a quantity of silicious material, applying suiiicient heat to said mixture to cause the same to become semi-plastic, and agitating the mass by rolling the same.

5. The process of agglomerating fine sulfid ore of copper which consists in mixing with said ore a quantity of silicious material, ap plying suflicient heat to said mixture to cause the same to become semi-plastic, and agitating the mass by rolling the same.

In testimony whereof I affix my signature,

in presence of two Witnesses.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of .Patents,

Washington, D. 0.