Method for extracting selenium from selenium-contained material

Abstract

The invention relates to a method for extracting selenium from selenium-deposited residue. The method comprises the following steps of: dissolving selenium-deposited residue to an alkaline sodium sulfite solution, generating water-soluble seleno sodium sulfate through a reaction between elemental selenium and the sodium sulfite solution; fully reacting the seleno sodium sulfate under the acidification of sulfuric acid to obtain a selenium elemental precipitate; and washing and drying to obtain coarse selenium with the purity of about 90 percent. The invention realizes separation of copper, silver and selenium in the selenium residue, and the separated selenium can be directly refined due to higher purity, therefore, the process flow of selenium recovery is shortened, the recovery rate is increased, and the production cost is decreased; the trouble of high copper content of an anode plate in silver electrolysis in the gold and silver refining process is solved and the pass rate of primary silver powder electrolysis is increased. The invention can be applied to recovering and extracting selenium from materials, such as selenium-contained residue generated in the technical process by using a wet method for treatment or selenium-contained acid mud generated in the production process of the copper anode slime by using a pyrogenic method for treatment and can also be applied to the production of high-purity selenium products by directly purifying a coarse selenium raw material.

Description

technical field [0001] The technology relates to the field of metallurgical technology, especially the technology for extracting crude selenium from raw materials containing silver, selenium, copper, lead, tellurium and other elements, specifically a process for separating and extracting selenium from materials containing selenium. Background technique [0002] At home and abroad, rotary kilns are often used to process copper anode slime, and sulfuration roasting is used to steam selenium to extract crude selenium. Now some enterprises use pressure leaching-fire smelting process to extract crude selenium. The main process is: copper anode slime is pressurized Leaching, the output leaching solution is replaced by copper powder to recover silver and selenium, the silver-selenium slag and the pressurized slag after pressure leaching are put into the Caldo furnace for smelting, and crude selenium is produced from the pyro-smelting flue gas recovery system. In the process of proc...

AI Technical Summary

Problems solved by technology

In the process of processing the copper anode slime pressurized leaching solution, the end point of selenium precipitation is not easy to detect. When the selenium content of the solution is particularly low, an excessive amount of copper powder is needed to replace a small amount of selenium, otherwise the selenium precipitation will not be complete. As a result, the selenium slag produced contains more than 30% copper, which is not conducive to the recovery of gold and silver in the subsequent Kaldor furnace smelting

Since the copper removal effect of the Kaldor furnace is not ideal, after these selenium slags with high copper content enter the furnace for smelting, the copper content in the output gold-silver alloy anode plate will be too high, so that the electrolytic silver powder in the gold-silver electrolysis process is qualified. rate reduction

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