A process for reducing arsenic content from arsenic-bearing gold concentrate or other arsenic-bearing gold materials to produce a low arsenic-bearing gold concentrate. The process may comprise adding oxygen, water, and/or acid to an acidulated arsenic-bearing gold concentrate slurry and reacting them together in an autoclave at an elevated pressure and temperature in a pressure oxidation step. In one or more examples, the process may further comprise processing the oxidized concentrate slurry in an arsenic re-dissolution step to dissolve unstable solid arsenic compounds, and applying a first solid/liquid separation and wash step to form a first washed slurry/solid and first acid-containing solutions. The process may further comprise reacting the first washed slurry/solid with sulfur dioxide in a reductive leach step, and applying a second solid/liquid separation and wash step to form a second washed slurry/solid and second acid-containing solutions. The second washed slurry/solid may be a low arsenic-bearing gold concentrate.

A process for reducing arsenic content from arsenic-bearing gold concentrate or other arsenic-bearing gold materials to produce a low arsenic-bearing gold concentrate. The process may comprise adding oxygen, water, and/or acid to an acidulated arsenic-bearing gold concentrate slurry and reacting them together in an autoclave at an elevated pressure and temperature in a pressure oxidation step. In one or more examples, the process may further comprise processing the oxidized concentrate slurry in an arsenic re-dissolution step to dissolve unstable solid arsenic compounds, and applying a first solid/liquid separation and wash step to form a first washed slurry/solid and first acid-containing solutions. The process may further comprise reacting the first washed slurry/solid with sulfur dioxide in a reductive leach step, and applying a second solid/liquid separation and wash step to form a second washed slurry/solid and second acid-containing solutions. The second washed slurry/solid may be a low arsenic-bearing gold concentrate.

Provided are a removal liquid for removing an oxide of a Group III-V element, an oxidation prevention liquid for preventing the oxidation of an oxide of a Group III-V element or a treatment liquid for treating an oxide of a Group III-V element, each liquid including an acid and a mercapto compound; and a method using each of the same liquids. Further provided are a treatment liquid for treating a semiconductor substrate, including an acid and a mercapto compound, and a method for producing a semiconductor substrate product using the same.

Provided are a removal liquid for removing an oxide of a Group III-V element, an oxidation prevention liquid for preventing the oxidation of an oxide of a Group III-V element or a treatment liquid for treating an oxide of a Group III-V element, each liquid including an acid and a mercapto compound; and a method using each of the same liquids. Further provided are a treatment liquid for treating a semiconductor substrate, including an acid and a mercapto compound, and a method for producing a semiconductor substrate product using the same.

A stabilization process for an arsenic solution comprising thiosulfates, the process comprising: acidifying the arsenic solution to decompose the thiosulfates, to yield an acidified solution; oxidizing the acidified solution to oxidize residual As.sup.3+ to As.sup.5+ and reduced sulfur species to sulfates, to yield a slurry comprising elemental sulfur; separating elemental sulfur from the slurry to yield a liquid; oxidizing the liquid to oxidize residual reduced sulfur species, to yield an oxidized solution; and forming a stable arsenic compound from the oxidized solution.

A stabilization process for an arsenic solution comprising thiosulfates, the process comprising: acidifying the arsenic solution to decompose the thiosulfates, to yield an acidified solution; oxidizing the acidified solution to oxidize residual As.sup.3+ to As.sup.5+ and reduced sulfur species to sulfates, to yield a slurry comprising elemental sulfur; separating elemental sulfur from the slurry to yield a liquid; oxidizing the liquid to oxidize residual reduced sulfur species, to yield an oxidized solution; and forming a stable arsenic compound from the oxidized solution.

A method for comprehensively processing noble lead provided and utilizes two instances of vacuum distillation to realize an open circuit of arsenic, lead, antimony and bismuth and the high-efficiency enrichment of precious metals of gold and silver, and can obtain elemental arsenic, a lead-bismuth-antimony alloy, a silver alloy and a copper alloy, respectively. The lead-bismuth-antimony alloy, the silver alloy and the copper alloy are processed by oxidation refining, electrorefining and chlorination refining to obtain refined lead, refined antimony, antimony trioxide, electrolytic silver and electrolytic copper, and to realize gold enrichment. The entire process has advantages of high metal direct yield, low energy consumption, short flow chart, simple equipment, etc., and vacuum distillation belongs to a physical process in which the alloy can be separated only by means of the difference in saturated vapor pressure between the metals, without generation of wastewater, waste gas and waste residue.

Disclosed is a method for the removal of arsenic from materials containing a high arsenic content, or materials containing a high content of arsenic and selenium.

Disclosed is a method for the removal of arsenic from materials containing a high arsenic content, or materials containing a high content of arsenic and selenium.

A method for immobilizing arsenic includes adding calcium arsenate to a glass-forming material containing iron, silica, and alkaline components so that an iron/silica weight ratio is in a range of 0.5 to 0.9 and an amount of alkaline components is in a range of 14 wt % to 26 wt %, and thereby incorporating the arsenic into a glass solidified body. For example, the method for immobilizing arsenic may include: adding an alkaline solution and an oxidizing agent to a copper-arsenic-containing substance, and thereby carrying out an oxidizing leaching; separating a leach residue by solid-liquid separation; adding calcium hydroxide to a recovered alkaline arsenate solution to generate calcium arsenate; and adding the glass-forming material to the recovered calcium arsenate so that the iron/silica weight ratio and the amount of alkaline components are in the above-mentioned ranges, and thereby incorporating the arsenic into the glass solidified body.