US1828756A - Process for the refining of chromium ores - Google Patents

Description

60. acid an Patented Oct. 27, 1931 UNITED STATES PATENT" orrlcs PA'O'L WEISE, 'WIESDOBF-ON-THE-RHINE, FRANZ SPEGHT,:OF OOLOGNE-ON-THE- RHINE, GERMANY, ASSIGNORS TO I. G. FABBEININDUSTBIE AKTIENGESELLSCHAFT, OF FBANKFORT-ON-THE-MAIN, GERMANY, A CORPORATION OF GERMANY PROCESS FOR THE BEFINING O F GHROMIUM OBES 80 Drawing. Application filed March 80, 1928, Serial No. 266,098, and in Germany April 18, 1927.

In the manufacture of chromium com-' pounds from chromium ores the impurities, such as silicic acid, alumina, magnesia and the like, present. in the gangue, often give 15 rise to serious difficulties, since they not only consume anequivalent quantity of the material used for working up the ores, butalso render the ultimate roduct impure and cause difliculties in working because the solutions so cannot be readily filtered.

In accordance with the present invention the ore is-subjected-to the action of alkalies in the absence of oxygen with the result that the gangue only is attacked, so that it will as be easily possible to separate the ore almost completely from the gangue without loss of chromium oxide occuring. By this sim le process inferior .ores can be converted wit out great'expense into hi h so percentage ores, which is important not on y in the manufacture of chromium compounds, but also in considerably reducing the'cost of transport. Besides this, the ore subjected to this prelimina treatment [is very easily as worked up so t at higher yields can be .ob

tained.

As agents for partial working up alkali metal hydroxides and ea'rbonates are suitable, employed either alonL-or in admixture with 10 one another or withsuch substances as lower the melting point. "The working up. can.

equally well be carried out either in the aqueous phase at temperatures above 100 C. with or without increased pressure, .Pyrogenis5 cally at the melting point of. the o rative' agent used for working up the ore. e ores thus treated, are quenched in water or in dilute alkali'solution, filtered land dried. 1 The workin%u agent and also the alumina, silicic j treating an ore under ike can be recovered from the filtrate in the known manner. It is likewise possible by treating the filtered, still damp sludge with dilute acids to further enrich the ore in regard to chromium oxide.

. The following examples will illustrate our lnventionz Ema/mple 1.-Finely ground chomium ore,

containing for example of Or o is mixed with the requisite quantity of caustic soda solution and heated in an autoclave in a nitrogen atmosphere to 200 C. with stirring. -When the working-up is complete, the oreis separated from the lye, washed with dilute. acid and dried. According to the source of the raw material, an ore is then ob-' tained containing from -7 0% of Cr O Example 2.-Finely ground chromium ore is mixed with the just requisite quantit of a mixture of sodium carbonate and so ium hydroxide and heated ina rotating furnace in the absence of oxygen to from 400-500" C.

The hot melt is quenched in water, the ore is separated .from the lye and dried. .The lye is worked up to obtain sodium carbonate,

alumina and silicic acid, while the high percentage chromium ore, thus obtained, is further worked-up according to one of the customary processes.

We claim: 1 In a process for the concentration of chromium ores, the step which comprises treating an ore-at temperatures above 100 C. with an alkali in the absence of oxygen. I

2. In a process for the concentration: of chromium ores, the step which comprises treating an ore at temperatures above C.

with an alkali metal hydroxide in the absence of oxygen.

3. In a process for the concentration of. chromium ores, the-step which comprises. treating an ore at temperatures above 100 C. with an alkali metal carbonate inthe absence of oxygen.

4. In a process for the concentration of ohromium ores, the 'step which comprises pressure at temperatures above 100 C. with an alkali in the absenceof oxygen.

5. In a process for the concentration of chromium ores, the: step which comprises treating an ore under pressure at temperatures above 100 C. with an alkali metal hydroxide in the absence of oxygen.-

6. In a process for the concentration of 6 chromium ores, the step which comprises treating an ore under pressure at tempera tures above 100 C. with an alkali metal carbonate in the absence of oxygen.

In testimony whereof we have hereunto 10 set our hands.

PAUL WEISE. FRANZ SPECHT.