United States Patent (19) (11) 4,078,917 Swanson 45) Mar. 14, 1978 54 EXTRACTION OF ANTIMONY TRIOXIDE from antimony sulfide ore concentrate by solubility FROMANTIMONY SULFDE ORE differential of the trioxide in lower alkanol solutions of 76 Inventor: Rollan Swanson, The Baker House, sodium or potassium hydroxide and wherein the total 220 California Ave., Santa Monica, amount of water contained in the concentrate, the alka Calif. 95405 nol and the hydroxide is not more than 26.52 volume percent of the antimony sulfide content; which process (21) Appl. No.: 652,093 includes treating the ore in the absence of substantial (22) Filed: Jan. 26, 1976 amounts of air with an alkanol solution containing an excess of sodium or potassium hydroxide, basis Sb2S3 51) Int. Cl’.............................................. C22B 30/02 content in the ore; separating also, in the absence of 52 U.S. C. .................................... 7.5/101 R; 7.5/108; substantial amounts of air, insoluble concentrate mate 75/121; 42.3/87; 423/617 rial from a filtrate composed of water, alkanol, hydrox 58) Field of Search ..................... 75/101 R, 121, 108; ide and sulfide of potassium or sodium, antimony triox 423/87, 617 ide trihydrate, sodium or potassium dihydro pyroan (56) References Cited timonite; repeatedly extracting the insoluble material U.S. PATENT DOCUMENTS with the filtrate also in the absence of substantial 796,849 8/1905 MacArthur ........................ 75/121 X amounts of air; allowing the filtrate to settle so as to 975,148 ill/1910 Masson .................................. 75/121 form a precipitate of antimony trioxide and sodium or 1,548,854 8/1925 Schleicher .. ... 42.3/87 X potassium dihydro pyroantimonite; separating the pre 1,646,734 10/1927 Marden .............. ..., 75/121 X cipitate from the filtrate; dehydrating the precipitate to 3,723,267 3/1973 Baiborodov et al. ... 75/121 X leave behind a mixture of antimony trioxide and hy 3,883,345 5/1975 Caldon et al. ..................... 423/87 X droxide of sodium or potassium; and adding the sepa Primary Examiner-G. Ozaki rated alkanol to the mixture to dissolve the hydroxide Attorney, Agent, or Firm-Albert F. Kronman and leave behind antimony trioxide. (57) ABSTRACT Disclosed is a process for extracting antimony trioxide 13 Claims, No Drawings 4,078,917 2 After mixing the antimony sulfide concentrate and EXTRACTION OF ANTMONY TRIOXDE FROM the alcohol solution of sodium or potassium hydroxide ANTMONY SULFIDE ORE and with an agitation supplied from 1 to 3 minutes at temperatures not exceeding 65° F the mixture is filtered. It is best to use full closed containers for the mixing and BACKGROUND OF THE INVENTION the filtration should be with limited access to atmo This invention relates to a novel process for recover spheric oxygen. This is to prevent any oxidation of ing antimony trioxide from antimony sulfide ores and antimony from the tri-valent state to the pentavalent Concentrates. state of oxidation. Filtration should be accompanied by The main object of this invention is to reduce the air, 10 agitation of the material to prevent caking on the sides water, thermal and chemical pollution inherent in pres and thus trapping some of the white precipitate material ent processes of making antimony trioxide. in the solid residues. No heat or pressure is used in the disclosed process Some of the finely divided white precipitate of anti itself and any reduced pressure or heat is used only in mony trioxide or antimony-potassium - oxygen hy recycling of the alcohol and sodium or potassium hy 15 drated compounds will pass a No. 4, 1 or 2 filter paper. droxide reagents. The bulk of the formation of these white precipitates The process is remarkably efficient in recovering occurs in the filtrate after it has passed the filter paper. antimony trioxide from antimony sulfide concentrates. This is due to the fact that sodium or potassium meta By excluding atmospheric oxygen and by the use of antimonite is unstable in water and the remainder is due closed and preferably full containers and filters and 20 to the pairing of sodium or potassium hydroxy antimo with the removal of excess sulfur through decomposi nite molecules when sufficient water is available for tion of the antimony pentasulfide attemperatures above their hydration to permit the formation of the com 75 C, it is possible to maintain antimony in a tri-valent pound empirically written as sodium or potassium di state of oxidation wherein no thio-antimonates are hydro pyro-antimonite. This compound is quite insolu formed. Antimony, in this tri-valent state, forms little 25 ble as the sodium compound and more soluble as the thio-antimonites, which tend to decompose to antimony potassium compound, and seems to be the principal tri-sulfide. precipitate formed in the filtrate. The amount of water Use of the solubility differential between antimony necessary to form this compound is an additional trioxide and antimony tri-sulfide in various alcohol 66.66% of the total amount of water formed in the solutions, coupled with the addition of sodium or potas 30 initial reaction. sium hydroxide to the alcohol solution, coupled with The total time for precipitation from the filtrate is up the inability of antimony to form a hydroxide produces to four hours. This time can be reduced by the addition an unpredictable reaction wherein antimony trioxide is of sufficient water to permit the required degree of the end product, hydration to occur. The ratios are: Antimony trioxide finds utility in the manufacture of 35 tartar emetic; as a paint pigment; in enamels and glasses; as a mordant; and in flame proofing. SbS35 + 6 KOH336 or 6 NaOH240 = 3 (KS)36 or 3 NaS3. + SbO3HO345 The reaction of the process according to the present followed by: invention is as follows: SbO3HO expressed as 2 (HSbO) + 2 HO + 2 NaOH or SbS + 6 KOH or 6 NaOH in an ethanol, methanol 2 335KOH = Na (or( K.) H.HSbO 5HO,E. 36 80 or other alcohol solution, (wherein the concentration is 112 3 for i i81 foŠ5 approximately 16.66% solution of KOH, or 8% solution of NaOH) = 3 KS or 3 NaS -- SbO3.3H2O. The The total amount of water required as 90 parts of sodium sulfide (mono) is only slightly soluble in ethanol water with the varius ratios to the other ingredients of or mehanol whereas the potassium sulfide is much more 45 the mixture (54 of the 90 is produced in the initial reac soluble. tion). In addition to the water of hydration formed during There is also the hydrolysis of the potassium sulfides the initial reaction, water is found as an impurity in the and sodium sulfides produced in the reaction: antimony sulfide concentrate in the sodium or potas sium reagents and in the alcohol reagents, 15.92% of the 50 KS + HO = KHS + KOH and NaS + HO = weight of SbS in the concentrate will be water. The NaHS -- NaOH upper limit of the water content is 26.52%. In the pres ence of this quantity of water, the following reactions Hydrolysis of the sodium or potassium sulfides occurs OCC: because the ratio of 6 KOH or 6NaOH is sufficient with 55 1 mole of SbS to complete the reaction all the way to 2 HSbO (antimonous acid - a representation of the sodium or potassium di-hydro pyro-antimonite--if trihydrated antimony trioxide) + 2 NaOH or 2 KOH + there were no hydrolysis the number of sodium and 2HO = Na(or K.) HSbO3.5H2O. This is the sodium potassium hydroxides in the equation would be 8. With or potassium dihydro pyro-antimonite. Various other sodium, the insolubility of the mono-sulfide in the alco derivations of a compound of the same empirical for hols requires a greater than 6 ratio, preferably 8. Potas mula exist through the sodium or potassium hydroxyan sium did not require a greater ratio than 6. timonite and sodium or potassium meta-antimonite. When formed 3-5 minutes have elapsed, the filtrate 2( (Na) or (K) Sb (OH).HO) = Na(or K) with the white precipitate forming in it can be centri HSbOSHO fuged and the solids removed. The clear filtrate is then 65 added to the residues in the filter paper and additional 2( (Na) or (K) SbO3HO) = Na(or K) extractions can be made which will continue to precipi HSbO3.5H2O tate in the filtrate after passing the filter paper. An ex traction of 97% of the antimony can be made by recy 4,078,917 3. 4 cling the proper amount of filtrate a fifth time. As little The following examples illustrate but do not limit the exposure to atmospheric oxygen as possible should be invention. All the parts given are by weight unless vol allowed in both the mixing the filtering and the re-addi umes are specified. tion of the clarified filtrate to the solid residues. When the re-use of the clarified filtrate is ended, the EXAMPLE I solids are removed from the filtrate-as much as 4 hours 100 grams of potassium hydroxide was dissolved in may be required to completely precipitate the white sufficient methanol to make a total volume of 300cc or substances. If the procedures are properly carried out 33.3%. The solution was allowed to cool to 50 F before there are no yellow formations on the filter paper from using. The solution was made in a stoppered 500cc formation of thio-stibnates nor are there any red-yel- 10 flask. low-brown residues from the decomposition of sodium The antimony sulfide concentrate contained 60% or potassium thio-stibnite into antimony tri-sulfide. antimony or 83.7% antimony sulfide.