Hydrometallurgy-indium replacement method for indium
Chemical and non-ferrous metal smelters output soot, slag, anode mud and mud acid indium are extracted material.
The replacement indium method is a common process in countries today to obtain crude indium.
The indium-containing raw material is subjected to acid leaching to obtain an indium-containing solution (for example, an indium-rich solution obtained by extraction when the content of indium in the liquid is low). Before substituting indium visual solution impurity profile or with iron when cuttings drop copper and arsenic, required to maintain the solution [Cu] / [As] = 1 ~ 2.5, the free acid 15 ~ 30g / L and 70 ~ 90 ℃, in Cu 3 As 2 form removes copper and arsenic, leaving [As]<0.02g/L in solution, so as not to cause AsH 3 poisoning when replacing indium; or introducing H 2 S into solution to make copper, arsenic and antimony sulfide slag was removed; or zinc powder added is less than the amount of indium sponge, substituted or added in advance to obtain a post-purged with copper, lead, tin, indium party sent replacement. The metal (Me) is more negative than the electrode potential of the indium (the following table). It is common to replace the indium (reduced to metal) from the solution by zinc and aluminum :
In 3+ +Me ==== In 0 ↓ +Me 3+
Technical control of substitution: If replacing indium from HInCl 4 solution, it is advisable to add NaCl or HCl to make the chloride ion concentration in the solution reach about 20g/L, pH=1.5~2, temperature 40~50°C, and the replacement tank keeps the negative pressure exhausted. Replace with zinc and aluminum sheets (if zinc is used, the replacement liquid is ZnCl2 liquid, generally containing 170~200g/L of zinc, and the zinc powder can be adjusted to ZnCl 2 grade to obtain commercial ZnCl 2 ; such as from In 2 (SO 4 ) 3 solution to replace indium, it is also advisable to add NaCl to 5~10 g / L, keep H 2 SO 4 15~50g / L, temperature 30 ~ 40 ° C, replace with zinc or aluminum sheet. Generally about 8 ~ 24h After the replacement is completed, the sponge-like indium containing about 90% to 95% of indium is scraped and stored in water to prevent oxidation. When the mold is molded, it is taken out from the water, pressed into a stainless steel pot, and covered with an indium weight of 50. %~60% of the alkali is heated to 320~350 °C for 2~3h to make the impurities (Me') into the slag and obtain the coarse indium of In≥99%.
Me '( II ) /Me ′( III ) +2NaOH ==== Na 2 Me ′ O 2 /2NaMe ′ O 2 +H 2 ↑
The replacement indium method is simple, economical and applicable.
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