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In sub-containing electrolytic method Pb- indium-based alloy (Pb-Me-In) separating crude indium, indium impurity to the former (Me ') separating enriched, purified to obtain the product as the latter.
A Pb-Me-In Electrolysis
The raw material for Pb-Me-In electrolysis is crude lead containing indium, Pb-Sn or Pb-Sb, etc. The electrolysis process is shown in the following figure.
Lan has used indium-containing crude lead or Pb-based alloy as the anode, and placed the separator into sulfamic acid (and H 2 NSO 2 OH) 100g / L, lead sulfamate [Pb (H 2 NSO 3 ) 2 ] In 80g/L and gelatin 0.4g/L electrolyte, pure Pb or pure Pb-based alloy is obtained by electrolysis at current density of 100A/m 2 , and indium is enriched in anode slime. Unfortunately, there is no report on recovery of indium; Russia – The factory uses this method to extract indium from Pb-Sb 3.5~8.5 containing indium, using pure lead or stainless steel as cathode, the electrolyte is sulfamic acid 28~65g/L, sulfamic acid lead 20~60g/L, plus β - Naphthol and gelatin were electrolyzed to obtain pure lead at a current density of 100-150 A/m 2 and a cell pressure of 0.2-0.3 V. Indium was recovered from the anode mud, and no reported indium was reported. This method is simple, the product quality is good and there is no pollution. H 2 NSO 2 is readily available, and ammonia synthesis and urea are dissolved in fuming sulfuric acid.
In addition, silicon fluoride acid electrolysis method for indium, China and Canada have been industrialized. When silicon-fluoric acid electrolysis Pb-Sn is used in China, indium is basically transferred to waste electrolyte (including H 2 SiF 6 210~260g/L, Sn 125~140g/L, Pb 50~60g/L and In 7.4~5.9g/ Indium is recovered in L). Using 30% D 2 EHPA to extract the difference of In 3+ and Sn 4+ , take o / a = 1/4 quantitative extraction of indium, and then use 6mol / L HCl back extraction to obtain indium aqueous phase, plus Na 2 CO 3 Adjust to pH=3 and precipitate the impurity tin . After replacing the tin with the sponge obtained by the former, the pH is adjusted to 1.0~1.5, and the indium is replaced by the zinc plate at 65 °C. The indium recovery rate is about 70%. Coinco Canada casts Sn-Pb as anode, pure Sn-Pb as cathode, electrolyzes pure Sn-Pb in H 2 SiF 6 electrolyte, indium enters anode slime in the form of Sn-In, and is immersed in sulfurized roasting. to give In 2 (SO 4) 3 solution, filtered off and replaced with the other sheet after crude indium, copper, zinc or aluminum sheet substituted with indium sponge obtained, to give 99.99% indium by electrolysis.
B crude indium electrolysis
The crude indium containing about 90% is electrolyzed in a H 2 SO 4 AK HCl medium to obtain 99.99% indium. A typical In 2 (SO 4 ) 3 electrolyte contains In 40 ~ 100g / L, NaCl 80 ~ 100g / L, crude indium is the anode, pure indium is the cathode, the current density is 300 ~ 500A / m 2 and 20 ~ 40 99.99% indium is obtained by electrolysis at °C; typical InCl 3 electrolyte contains 20~80g/L of indium, 100g/L of NaCl, (only 50g/L with NH 4 Cl), the additive is as before, pH=2.0~2.5, 99.99% indium is electrolyzed at a current density of 60 to 100 A/m 2 , a cell pressure of 0.25 to 0.4 V, and room temperature.
The obtained electrolytic indium thallium-containing impurities and more can be accompanied by NH 4 Cl and ZnCl 2 (respectively 1.5% by weight of indium and 4.5%) melting at 280 deg.] C so that the dross thallium comprehensive recovery. The multiple compartments containing iodide, available methods: I added at 200 ℃ 2, KCl, and glycerin cadmium dissolved in K 2 CdI 4-glycerol; volatiles in vacuo at 90 deg.] C and cadmium is removed and utilization.