A method for removing arsenic in nickel electrolytic mixed acid system

Abstract

The invention discloses an arsenic removal method in a nickel electrolysis mixed acid system. According to the method, the iron-arsenic ratio of anodic electrolyte is reasonably controlled through iron supplementation, and meanwhile, the temperature and pH value of an iron removal process are controlled, so that 80% or more of arsenic is separated out in an iron arsenate or adsorption form in the iron removal process; then, in the cobalt removal stage, the cobalt removal oxidation potential, reaction time and pre-cobalt-removal liquor pH value are controlled, and remaining arsenic in iron removal and arsenic removal filtered liquor is removed with cobaltous hydroxide at the cobalt removal stage in a coprecipitation manner. Besides, iron removal and arsenic removal filtered slag generated by purification and cobalt removal and arsenic removal filtered slag are subjected to nickel removal treatment and then filtered, filtered liquor returns to liquor making for treatment, part of arsenic is brought to the liquor making process, and arsenic removal is induced by controlling solution copper ions and electric current density in the liquor making process. By means of the method, the problem that arsenic contained in nickel electrolysis exceeds standards is well solved, the arsenic contained in electrolysis new liquor is smaller than 0.0002 g / l, the arsenic contained in electrolytic nickel is smaller than 0.0005%, and the arsenic removal rate in a solution of a whole system reaches 98% or above.

Description

technical field [0001] The invention belongs to the technical field of nickel electrolysis, and in particular relates to a method for removing arsenic in a nickel electrolysis mixed acid system. Background technique [0002] The nickel sulfide soluble anode diaphragm electrolysis process used in nickel electrolysis uses a high-matte anode plate as the anode in the electrolysis process, and the nickel starting plate as the cathode. The nickel electrolysis anolyte is purified and pumped to the cathode chamber of the electrolytic cell to produce new electrolytic solution. Under the action of direct current, the nickel ions in the catholyte are precipitated at the cathode to obtain electrolytic nickel. In the process of nickel electrolysis, due to the gradual increase in the arsenic content of purchased nickel concentrate and the tempering method of arsenic-containing slag from nickel electrolytic wet smelting, the arsenic content of high-nickel matte in top-blown furnaces incre...

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Problems solved by technology

In the process of nickel electrolysis, due to the gradual increase in the arsenic content of purchased nickel concentrate and the tempering method of arsenic-containing slag from nickel electrolytic wet smelting, the arsenic content of high-nickel matte in top-blown furnaces increased from 0.095% in 2012 to 2013 0.107% in 2009, resulting in the continuous increase of arsenic content in the nickel electrolytic anolyte. Since there is no method for removing arsenic in the nickel electrolytic mixed acid system, the anolyte arsenic enters the new electrolytic solution after the purification process, making the arsenic content in the new electrolytic solution exceed 0.0003g / L, so that the arsenic content of electrolytic nickel exceeds 0.00085% of the Ni9996 national technical standard requirements, and when the content of impurity elements in electrolytic nickel exceeds the national technical standard of electrolytic nickel, the sales will be downgraded (reduced price), which will affect the economic benefits of electrolytic nickel

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