US1249061A - Process for producing spelter. - Google Patents

Description

CHARLES H. FULTON, OF ST. LOUIS, MISSOURI, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

METALLURGICAL LABORATOBIE$, INCO PORATION OF ILLINOIS.

RPOBATED, 0F CI'ICAGO, ILLINOIS, A COR- manner;

No Drawing.

To all whom it may concern:

Be it known that I, CHARLES H. FUL'roN, a citizen of the United States, residing at St. Louis, Missouri, have invented a certain new and useful Improvement in Processes for Producing Spelter, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

tion, or by electrolyzing pure zinc solutions,

or by distilling impure spelter or other material containing metallic zinc. When spelter is made by the latter method it is called redistillation and is ordinarily carried out in a modified form of the ordinary well known retort furnace.

One object of my present invention is to provide a novel process by which a good grade of spelter can be roducedat a low cost from blue powder, zlnc dross and zinc ashes, impure spelter and other zinc-bearing materials containing zinc in the metallic form, obtained directly or indirectly by the treatment of zinc ores.

Another object is to provide a distilling process for the purpose described that can be accurately controlled. Other objects and desirable features of my invention will be hereinafter pointed out.

Briefly described, my process consists in forming zinc-bearing material containing zinc in the metallic form, into objects that will retain their substantially original form and volume when heated to a dist1lling temperature, subjecting said objects to treatment in a distilling furnace, so as to convert the metallic zinc in the material into vapor, and thereafter, condensing the zinc vapor into spelter in'a condenser.

The material from which the said objects are formed may consist of blue powder, zinc dross and zinc ashes, impure spelter, or, in fact, any zinc-bearing material containing zinc in the metallic form, produced either directly or indirectly by the treatment of zinc ores. While it is immaterial, so far as my broad idea is concerned, how sald ob- I Specification of Letters Patent.

Application filed January 22, 1917. Serial No. 143,795.

Patented Dec. 4, 1911'? jects are formed, I prefer to form them by combining finely-divided zinc-bearing materlal of any suitable kind containing zinc in the metallic form and a binding material in certain proportions, heating said mixture and forming it into solid objects under high pressure. The reducmg a ent that I prefer to use is pulverized co e and the binding material is either tar or hard coal tar pitch, as objects formed in the manner previously described from such materials and zinc-bearing material containing zinc in the metallic form have the same essential characteristics and desirable features as the ore briquets described in my prior U. S. Patent N 0. 1,193,- 680, dated August 8, 1916, namely, they remain intact and preserve their form and volume throughout the distilling operation to which they are subjected. The purpose of heating the mixture during the process with a reducing agent.

other suitable carbonaceous material may be used in place of hard coal tar pitch. Other reducing agents than coke may also be used, but it is preferable to use coke, as it contains no volatile matter to be driven off preliminary to distillation; it gives rise to no gas during the distilling operation, except the carbon monoxid formed by the union of its carbon with the oxygen of the zinc oxid, which union constitutes the reducing reaction, and as its particles have assumed what may be considered their final form at the time the coke is incorporated in the briquet, said particles will not break down during the distilling operation, thus insuring the continued stability of the briquet during and after the distilling operation.

The shape of the briquets is immaterial, but in practice I form the mixture into briquets of spherical or cylindrical form in molds wherem they are subjected to a pressure of between 500 lbs. and 1,000 lbs. per square inch, so as to solidify the mixture and form it into a compact mass that will not swell and crack during the subsequent drying and distilling operations. When a carbonaceous binding material is used, it is as i necessary to preheat the briquets prior to the distilling operation, so as to drlve off the volatile matter in the bindin material and convert said material into co e, thus elimit mating the possibility of the zinc vapor being diluted by volatile hydrocarbons m the distilling operation. This preheating of the briquets also tends to make the brlquets better electrical conductors and is advantageous if the briquets are electrically distilled, as hereinafter described. In the preheating and dryin operation just referred to it is desirable t at the briquets be protected from the action of oxygen, so as to prevent the coke in the outer surface of the briquets from oxidizing, and thus causing the outside of the briquet to assume a loose and friable condition, with resulting disintegration of the surface of the briquet. It is also necessary, when tar 'is used as the binder, to support the briquets in some suitable manner during the preheating operation, so as to prevent them from breaking down or collapsing. The preheating operatlon may consist of a separate and distinct step or the preheating and distillation of the briquets can be merged into practically one operation by arranging raw briquets in the distilling chamber, and there heating them either by the stored heat in said chamber, or by any other means.

The proportions of the coke and the metallic zinc-bearing materials should be such that a suilicient mass of porous material will be left in the briquet after the distilling operation to maintain substantially the original volume of the briquet. The proportions of course will vary with different metallic zinc-bearing materials, but as a general rule, the amount of coke used should be suflicient so that the weight of the briquet, after distillation, will not be less than 40% to 50% of the weight of the briquet before distillation. The amount of binding material used also varies with the degree of fineness of the coke and the metallic zinc-bearing material, but sufficient binding material should be used to cause the particles of coke and zinc-bearing ma terial to be completely surrounded by a film of binder which unites them together into a coherent mass. I have found that satisfactory briquets are produced if the amount of binder is between 12% and 15% of the weight of the metallic zinc-bearing material, plus the weight of the coke, when moderately fine coke such as will pass through a ten-mesh screen and metallic zinc-bearing material, such as will pass through a ten-mesh screen, or finer, are used. It is essential that the metallic zinc-bearing material be in a relatively fine state of division at the time it is mixed with the coke and binder. Blue powder, zinc ashes, etc., 65 are naturally so, and therefore, require no preliminary treatment, but crude spelter has to be converted into granular form, for example, by melting and granulating in water, before it is mixed with the-binder and the coke. It is also desirable that the coke be finely ground, as such coke will produce a much stronger briquet than moderately fine or comparatively coarse coke.

After the briquets have been formed in the manner above described, they are distilled in a distilling furnace, so as to cause the metalliczinc in same to be driven ofl in the form of vapor, and thereafter, the zinc vapor is admitted to a zinc condenser, wherein it is converted into spelter. The briquets can either be subjected to the usual zinc-distilling operation in the retorts of a spelter furnace, or they can be electrically distilled. I prefer to electrically distil the briquets in the manner described in my ending application Serial No. 109,724, file July 17 1918, which briefly described, consists in interosing one or more briquets as a continuous, xed resistor between electrodes in a closed retort furnace and passing through them an electric current of such strength as will cause the briquets to be heated to a distilling temperature. By varying the amount of current passed through the briquets the speed of distillation may be kept under perfect control and the rateof distillation be varied at will, the current being preferably supplied to the furnace through a transformer so designed as to supply current of different voltage. If the current is too great or too small at any given voltage, the voltage of the transformer may be decreased or increased until the proper flow of current is obtained. The amount of current passed through the briquets is preferably at first relatively small, so that the walls of the retort chamber of the furnace in which the briquets are arranged will be heated rather gradually to about 700 C. or about 800 C. by radiation from the briquets. The current he may then be rapidly increased and the briquets raised to a distilling temperature.

It is immaterial what type of condenser .is used for converting the zinc vapor into spelter, but I prefer to effect the recovery of the zinc in a condenser of the kind described in my pending application Serial No. 141,177, filed January 8, 1917, which is so constructed that it can be either heated or cooled, so as to maintain it within the proper temperature range.

By forming zinc-bearing materials containing zinc 1n the metallic form into objects or briquets of the character previously described and then distilling said briquets, I am able to recover a greater percentage of the zinc content of the material than is possible with any of the processes heretofore used in the manufacture of spelter practically free from the usual purities, 13o

impure metallic zine-bearing materials are used for the purpose of redistillation, in that the control of the distillationgsas re gards time and temperature, is veryclose. This control is of particular advantage in the production of high grade spelter, since by distilling at the beginning at a relatively low temperature, most of the cadmium can be eliminated and some high cadmium spelter produced, after which the temperature may be adjusted to produce very pure spelter free from cadmium, lead and iron, the lead not being appreciably distilled until a relatively hlgh temperature is reached, By proper manipulation of the condenser, namely, draining the zinc therefrom, at the right time, the different grades v,of spelter may be kept separate. 7

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is: i

1. A process for manufacturing spelter, Y

which consists in forming zinc-bearing material containing zinc in the metallic form into objects that will retain substantially their original form and volume when subjected to zinc distillation temperatures, heating said objects to convert the metallic zinc in the same into vapor, and thereafter condensing said zinc vapor into spelter.

2. A process for obtaining spelter, which consists in combining finely-divided, zinc-' bearing material containing zinc in the metallic form with a reducing agent and a binding material and forming said mixture into objects that will retain their approximately original form and volume when subjected to zinc distillation temperatures,

heating said objects so as to drive ofi' the metallic zinc in the form of vapor, and thereafter converting said vapor into spelter.

3. A process for obtaining spelter, char-- acterized by combining finely-divided, zincbearing material containing zinc in the metallic form with coke and a carbonaceous binding material and forming said mixture into briquets under pressure, heating said briquets sufficiently to drive off the volatile matter in the carbonaceous binding material and heating said briquets, and there after converting the Zinc vapor evolved in the distilling operation into spelter.

4. A-process for obtaining spelter, which consists in combining zinc-bearing material containing zinc in the metallic form with a reducing agent and a binding material of the charactermentioned and in approximately the proportions specified, converting said mixture into briquets that will not disintegrate when they are subjected to zinc distillation temperatures, and thereafter heating said briquets and condensing the vapor evolved in the distilling operation into s elter.

5. process for obtaining spelter, which consists'in forming zinc-bearlng material containing-zinc in the metallic form into briquets that are substantially free from hydrocarbon substances or compounds and which wilretain their substantially original form and volume when subjected to zinc distillation temperatures, heating said briquets so as to drive ofi' the metallic zinc in same in the form of vapor, and thereafter condensing said vapor into spelter.

6. A process for obtaining spelter, which consists in forming zinc-bearing material containing zinc in the metallic form into briquets that will retain their substantially original form and volume when subjected to zinc distillation temperatures, interposing one or more of said briquets as a continuous resistor between the electrodes of an electric furnace and passing a current of electricity through them to heat them to a distillation temperature, and thereafter condensing the zinc vapor evolved by the-heating of the briquets into spelter.

7. A process for forming briquets for use in the manufacture of spelter, characterized by combining zinc-bearing material containing. zinc in the metallic form with a reducing agent and a binding material in proper proportions, forming said mixture into briquets under pressure, and thereafter heating said briquets so as to drive ofi' any hydrocarbon compounds in same which would tend to dilute the zinc vapors evolved in the subsequent operation of heating the briquets.

8. A proces for manufacturing spelter, which consists in forming compressed objects from finely divided spelter or zinc dross, coke and a binding material mixed in such proportions that said objects will retain their substantially original form and volume when subjected to zinc distillation temperatures, heating said objects to convert the metallic zinc in same into vapor, and thereafter condensing said vapor into spelter.

9. A briquet for use in the manufacture of spelter composed of zinc-bearing material containing zinc in the metallic form, a reducing agent and a binding material combined into a compact mass that will retain its substantially original form and volume of spelter formed from finely-divided particles of zinc-bearing material containing zinc.

in the metallic form, a finely-divided reducing agent, and a substance that unites the particles of said material and reducing agent into ,a coherent mass that Will retain substantially its original form and volume when subjected to a zinc distilling temperature.

11. A briqnet for use in themanufacture of spelter, consisting of a compressed object composed of finely-divided, zinc-bearing maaoca material containing zinc in the metallic form, and a coke matrix, formed from a reducing agent and a carbonaceous binding substance in which the particles of sai material are embedded.

12. A briquet for use in the manufacture of spelter," consisting of a compressed object composed of finely-divided, zinc-bearing material containing zinc in the metallic form, coke, and the coked residue of a carbonaceous binder, such as tar or pitch.

CHARLES H. FULTON.