(1) Hydrolysis method The main elements such as copper , zinc , cadmium and indium are separated by adjusting the different pH values ​​of various elements during hydrolysis, and the indium hydroxide can be completely precipitated at pH=4.67 to 4.85.
(2) Selective Dissolution and Precipitation Method Dissolving the indium-containing precipitate in sulfuric acid allows most of the lead to precipitate as a poorly soluble sulfate and separate from the indium. The hydroxide precipitate is treated with a caustic soda solution to bring aluminum , zinc and lead into solution, while indium remains in the precipitate for separation from indium. The indium-containing solution is treated with ammonia to co-precipitate indium with iron and aluminum, and copper, cadmium and zinc are added to the solution to form an ammonia salt. The phosphorus acid salts from the weak acid solution (PH = 3.2) precipitated indium, and indium can lead, zinc, iron and cadmium separation.
(3) selective displacement method using a metal deposition potential different selective accumulation of indium, zinc powder can be replaced with the copper in the first solution, after the addition of copper, indium and cadmium zinc can be replaced with various other elements separated.
The zinc oxide roasting leaching of Zhuzhou Torch Metal Co., Ltd. adopts neutral and acidic two-end leaching process, and then replaces the enriched indium with zinc powder. By adopting a series of improvements in the process, the recovery rate of zinc indium oxide is about 40%. Increased to over 55% now. The main chemical reactions are as follows:
ZnO+H 2 SO 4 =ZnSO 4 +H 2 O
In 2 O 3 +3H 2 SO 4 =In 2 (SO 4 ) 3 +3H 2 O
In 2 (SO 4 ) 3 +3Zn=3ZnSO 4 +2In↓
(4) Extraction of indium P204 is an acidic phosphate extractant, usually in the form of a bimolecular form, which can form a compound with a trivalent element. This compound does not contain a hydrophilic group, so it is hardly soluble in water, and is easily soluble in an organic solvent and can react with the same series of metal ions. Its extraction rate for various ions is a function of the pH of the solution, so controlling the different pH values, the efficiency of extraction of each metal ion is also different. The indium special effect extractant has not been found in China, and the indium extraction mechanism of the acidic phosphorus extractant has been studied. The order of the indium extraction ability of the phosphorus extractant is as follows: P204>P5708>P507>P5709, anti-extraction ability On the contrary, they are arranged in the order of P5709>P507>P5708>P204. Industrial commonly used extractants have the advantages of stable performance, low price and easy operation.
The P204 extractant has good selectivity to indium, and indium is extracted from the indium-containing solution, so that the indium enters the organic phase, and is separated from the copper, zinc, cadmium and arsenic and the ferrous iron which are difficult to extract in the aqueous phase. The indium entering the organic phase is back extracted by a high concentration of hydrochloric acid, and the indium enters the aqueous phase to obtain an aqueous solution of indium containing hydrochloric acid.
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