Value state regulation and control method for arsenic leaching through arsenic sulfide oxygen control

Abstract

The invention discloses a valence state regulation and control method for arsenic leaching through arsenic sulfide oxygen control. The valence state regulation and control method comprises the following steps that firstly, preparation before slurrying is conducted, wherein sulfuric acid is added into liquid obtained after arsenic removal to adjust the liquid obtained after arsenic removal; step 2, slurrying: adding copper sulfate with the mass fraction of 5% into the arsenic sulfide slag, uniformly mixing, and then adding the adjusted arsenic-removed liquid; step 3, slurry adjustment and preheating: preheating the slurry to 70-80 DEG C, and adjusting the slurry by using the adjusted arsenic-removed liquid; 4, arsenic sulfide slag oxygen control leaching, wherein the mixed solution obtained in the step 3 is transferred into a reaction kettle; 5, reduction of the arsenic immersion liquid through SO2, wherein a certain amount of SO2 is added into the arsenic immersion liquid, and As < 5 + > in the arsenic immersion liquid is reduced into As < 3 + >; and step 6, cooling crystallization: cooling the solution obtained in the step 5 to 30 DEG C or below, separating out arsenic trioxide crystals, and filtering and purifying to obtain the arsenic trioxide crystals with higher purity. According to the method, the concentration of As < 5 + > in the arsenic immersion liquid is reduced, so that the usage amount of SO2 during reduction is reduced, the production cost of white arsenic is reduced, and the economic benefit is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of solid waste slag resources, and specifically relates to a method for regulating the valence state of arsenic in oxygen-controlled leaching of arsenic with arsenic sulfide. Background Art

[0002] Arsenic is an element that is extremely harmful to the ecological environment and human body. Elemental arsenic and some arsenic compounds are highly toxic substances. Arsenic in nature is mainly enriched in non-ferrous metal minerals such as copper, zinc, lead, nickel, cobalt, gold and silver. In the process of non-ferrous metal smelting, these raw ores are treated by smelting process and exist in the slag in the form of sulfide, forming arsenic sulfide slag. Arsenic sulfide slag contains a variety of heavy metal elements such as Cu and Pb, which can easily enter the soil through rainwater scouring and infiltration, causing soil pollution and affecting soil productivity. At the same time, these heavy metals will also affect the stability of aquatic ecosystems and have toxic effects on organisms. Moreover, long-term exposure to a small amount of arsenic sulfide in the human body may lead to chronic poisoning and cause cardiovascular disease. Large intake may lead to acute poisoning, with symptoms such as nausea and vomiting, and may even lead to death in severe cases.

[0003] At present, the main wet treatment methods for arsenic sulfide waste residues include copper sulfate replacement method, oxygen controlled leaching method, nitric acid oxidation method, alkaline leaching method, ferric sulfate oxidation leaching method and copper chloride leaching method. Wet treatment of arsenic sulfide waste residues can efficiently leach arsenic, and the obtained As2O3 product has high purity, but the arsenic recovery rate is low. Using oxygen pressure leaching to treat arsenic sulfide slag can also efficiently leach arsenic, but most of the arsenic in the leachate is As 5+ In the production of white arsenic, a large amount of reducing agent needs to be added, and the consumption of chemicals is large, which makes the cost of producing white arsenic high. Therefore, the optimal process conditions for improving the leaching rate still need further research.

[0004] Although oxygen pressure leaching of arsenic sulfide slag can avoid the problems of pyrometallurgical treatment of arsenic sulfide slag, As in the leaching solution 5+ The content is extremely high, and a large amount of SO2 will be used when reducing the arsenic leaching solution, which makes the production cost high. The present invention provides a technology for controlling the valence state of arsenic in arsenic sulfide slag by controlling oxygen leaching. This method can reduce the As content in the arsenic leaching solution of arsenic sulfide slag. 5+ concentration, reducing the amount of SO2 in the arsenic leaching solution during reduction, thereby reducing the cost of treating arsenic sulfide slag to produce white arsenic. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a method for regulating the valence state of arsenic in oxygen-controlled leaching of arsenic with arsenic sulfide to solve the technical problems mentioned in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for regulating the valence state of arsenic in oxygen-controlled leaching of arsenic by arsenic sulfide, comprising the following steps:

[0007] Step 1, preparation before slurrying: adding sulfuric acid to the dearsenicated liquid to adjust the dearsenicated liquid to adjust the sulfuric acid concentration in the dearsenicated liquid to 95-110 g / L;

[0008] Step 2, slurrying: add 5% by mass of copper sulfate to the arsenic sulfide slag and mix evenly, then add the adjusted dearsenicized liquid, the liquid-to-solid ratio in the slurry is 4:1, and the slurrying time is 2 hours;

[0009] Step 3: Slurry adjustment and preheating: preheat the slurry to 70-80°C, and use the adjusted arsenic-free liquid to adjust the slurry so that the solid-liquid ratio in the slurry becomes 8:1;

[0010] Step 4: oxygen-controlled leaching of arsenic sulfide slag: transfer the mixed solution after step 3 into a reactor, adjust the oxygen partial pressure of the reactor to 400-500 kPa, and adjust the temperature of the slurry in the reactor to 95-110° C., and control the leaching time to 4 hours;

[0011] Step 5: SO2 reduction of arsenic leaching solution: Add a certain amount of SO2 to the arsenic leaching solution, control the reduction temperature below 90°C, and the reduction time is 2h to reduce As in the arsenic leaching solution. 5+ Reduction to As 3+ ;

[0012] Step 6: Cooling and crystallization: The temperature of the solution obtained in step 5 is lowered to below 30°C, and arsenic trioxide crystals are precipitated. After filtration and purification, arsenic trioxide crystals with higher purity are obtained.

[0013] Furthermore, the arsenic sulfide slag in the step 2 is produced in the copper smelting process, and its main components are: As (52.37%), Bi (0.042%), Cu (0.061%), Fe (0.19%), Pb (0.45%), Sb (0.019%), Zn (0.02%), S (36.93%), and Re (0.1%).

[0014] Furthermore, in step 4, the leaching temperature is 95-110° C., the leaching time is 4 h, the sulfuric acid concentration of the added arsenic-removed liquid is 95-110 g / L, and the oxygen partial pressure in the reactor is 400-500 kPa.

[0015] Further, in step 5, As 5+ The molar ratio of ions to SO2 is 1:1.3.

[0016] Furthermore, in step six, the arsenic sulfide leaching solution is cooled and crystallized after reduction, and the temperature of the arsenic sulfide leaching solution is below 30°C.

[0017] In summary, the present invention mainly has the following beneficial effects:

[0018] 1. Reduce As in arsenic sulfide slag during leaching3+ Oxidation to As 5+ :

[0019] Although oxygen pressure leaching can improve the arsenic leaching rate in the arsenic sulfide slag, most of the arsenic in the arsenic sulfide slag leachate exists in the form of pentavalent arsenic. When cooling and crystallizing to recover white arsenic, pentavalent arsenic is difficult to crystallize and precipitate. This method can reduce the concentration of pentavalent arsenic in the arsenic sulfide slag leachate during arsenic sulfide leaching.

[0020] 2. Reduce the cost of oxygen pressure leaching to treat arsenic sulfide slag:

[0021] In oxygen pressure leaching of arsenic sulfide slag, part of the trivalent arsenic in the arsenic leaching solution will be oxidized to pentavalent arsenic. When the white arsenic is subsequently recovered, the pentavalent arsenic in the arsenic leaching solution needs to be reduced to trivalent arsenic before the subsequent white arsenic recovery can be carried out. This method can reduce the use of reducing agents, thereby reducing the cost of oxygen pressure leaching for arsenic sulfide treatment;

[0022] 3. Avoid the problem of waste liquid generated by wet treatment of arsenic sulfide slag:

[0023] When treating arsenic sulfide waste slag by wet method, waste liquid will be generated after the treatment of arsenic sulfide waste slag. Using this method, after the white arsenic is recovered, the dearsenicated liquid can be continuously used for oxygen-controlled leaching of arsenic sulfide slag after adding sulfuric acid for adjustment, thus realizing the recycling of the dearsenicated liquid, thereby reducing the waste liquid generated by the wet treatment of arsenic sulfide slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0026] The following describes an embodiment of the present invention based on its overall structure.

[0027] like Figure 1 As shown, the specific operation includes the following steps:

[0028] Step 1, preparation before slurrying: add sulfuric acid to the dearsenicated liquid to adjust the dearsenicated liquid, and adjust the sulfuric acid concentration in the dearsenicated liquid to 95-110g / L; dry, grind, crush, and sieve the arsenic sulfide slag for later use, the arsenic sulfide slag is produced in the copper smelting process, and its main components are: As (52.37%), Bi (0.042%), Cu (0.061%), Fe (0.19%), Pb (0.45%), Sb (0.019%), Zn (0.02%), S (36.93%), Re (0.1%);

[0029] Step 2, slurrying: add 5% by mass of copper sulfate to the arsenic sulfide slag and mix evenly, then add the adjusted dearsenicized liquid, the liquid-to-solid ratio in the slurry is 4:1, and the slurrying time is 2 hours;

[0030] Step 3: Slurry adjustment and preheating: preheat the slurry to 70-80°C, and use the adjusted arsenic-free liquid to adjust the slurry so that the solid-liquid ratio in the slurry becomes 8:1;

[0031] Step 4: Oxygen-controlled leaching of arsenic sulfide slag: transfer the mixed solution after step 3 into a reactor, adjust the oxygen partial pressure of the reactor to 400-500 kPa, and adjust the temperature of the slurry in the reactor to 95-110 ° C, control the leaching time to 4 hours, and the arsenic in the arsenic leaching solution is mainly As 3+ and As 5+ The oxygen pressure condition is controlled to reduce the As in the arsenic sulfide leaching solution. 5+ The content of arsenic is reduced, thereby reducing the amount of SO2 used in the arsenic leaching solution during reduction and reducing costs. The leaching temperature is 95-110°C, the leaching time is 4h, the sulfuric acid concentration of the added arsenic removal solution is 95-110g / L, and the oxygen partial pressure in the reactor is 400-500kpa;

[0032] Step 5: SO2 reduction of arsenic leaching solution: Add a certain amount of SO2 to the arsenic leaching solution, control the reduction temperature below 90°C, and the reduction time is 2h to reduce As in the arsenic leaching solution. 5+ Reduction to As 3+ , in order to produce white arsenic, As 5+ The molar ratio of ions to SO2 is 1:1.3;

[0033] Step 6: Cooling and crystallization: The temperature of the solution obtained in step 5 is lowered to below 30°C, and arsenic trioxide crystals are precipitated. After filtration and purification, arsenic trioxide crystals with higher purity are obtained.

[0034] The present invention is specifically:

[0035] Example 1

[0036] Take 300 kg of arsenic sulfide slag and use oxygen pressure method to leach the arsenic sulfide slag. The As in the obtained arsenic leaching solution is5+ 、As 3+ The concentrations of arsenic sulfide are 30.22 g / L and 28.53 g / L respectively. The method of the invention is used to leach arsenic sulfide. 300 kg of arsenic sulfide slag is taken, 1200 kg of the adjusted arsenic removal solution is added, slurrying for 2 hours, and then 900 kg of the adjusted arsenic removal solution is added. After the slurry is preheated to 70°C, it is transferred to an autoclave, the oxygen partial pressure is adjusted to 400 kpa, the leaching temperature is 95°C, and after leaching for 4 hours, As in the leachate is 0.1%. 5+ 、As 3+ The purity of arsenic in the white arsenic obtained by cooling and crystallization can reach 98%.

[0037] Example 2

[0038] Take 300 kg of arsenic sulfide slag and use oxygen pressure method to leach the arsenic sulfide slag. The As in the obtained arsenic leaching solution is 5+ 、As 3+ The concentrations of arsenic sulfide waste residue were 30.22 g / L and 28.53 g / L respectively. The method of the invention was used to leach arsenic sulfide waste residue. 300 kg of arsenic sulfide residue was taken, 1200 kg of the adjusted arsenic removal solution was added, slurrying for 2 hours, and then 900 kg of the adjusted arsenic removal solution was added. After the slurry was preheated to 70 ° C, it was transferred to an autoclave, the oxygen partial pressure was adjusted to 500 kpa, the leaching temperature was 105 ° C, and after leaching for 4 hours, As in the leachate was 5+ 、As 3+ They are 19.73kg and 40.22kg respectively. SO2 is then added to reduce the arsenic leaching solution. The purity of arsenic in the white arsenic obtained by cooling and crystallization can reach 98%.

[0039] Although an embodiment of the present invention has been shown and described, this specific embodiment is only an explanation of the present invention and is not a limitation of the invention. The specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions and variations to the embodiments without creative contributions as needed without departing from the principles and purpose of the present invention. However, as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for regulating the valence state of arsenic in arsenic sulfide oxygen-controlled leaching, characterized in that: The following steps are involved: Step 1, preparation before slurrying: adding sulfuric acid to the dearsenicated liquid to adjust the dearsenicated liquid to adjust the sulfuric acid concentration in the dearsenicated liquid to 95-110 g / L; Step 2, slurrying: add 5% by mass of copper sulfate to the arsenic sulfide slag and mix evenly, then add the adjusted dearsenicized liquid, the liquid-to-solid ratio in the slurry is 4:1, and the slurrying time is 2 hours; Step 3: Slurry adjustment and preheating: preheat the slurry to 70-80°C, and use the adjusted arsenic-free liquid to adjust the slurry so that the solid-liquid ratio in the slurry becomes 8:1; Step 4: oxygen-controlled leaching of arsenic sulfide slag: transfer the mixed solution after step 3 into a reactor, adjust the oxygen partial pressure of the reactor to 400-500 kPa, and adjust the temperature of the slurry in the reactor to 95-110° C., and control the leaching time to 4 hours; Step 5: SO2 reduction of arsenic leaching solution: Add a certain amount of SO2 to the arsenic leaching solution, control the reduction temperature below 90°C, and the reduction time is 2h to reduce As in the arsenic leaching solution. 5+ Reduction to As 3+ ; Step 6: Cooling and crystallization: The temperature of the solution obtained in step 5 is lowered to below 30°C, and arsenic trioxide crystals are precipitated. After filtration and purification, arsenic trioxide crystals with higher purity are obtained.

2. The method for controlling the valence state of arsenic leaching by arsenic sulfide oxygen control according to claim 1, characterized in that: The arsenic sulfide slag in the step 2 is produced in the copper smelting process, and its main components are: As (52.37%), Bi (0.042%), Cu (0.061%), Fe (0.19%), Pb (0.45%), Sb (0.019%), Zn (0.02%), S (36.93%), and Re (0.1%).

3. The method for controlling the valence state of arsenic leaching by arsenic sulfide oxygen control according to claim 1, characterized in that: The leaching temperature in step 4 is 95-110° C., the leaching time is 4 hours, the sulfuric acid concentration of the added arsenic-removed liquid is 95-110 g / L, and the oxygen partial pressure in the reactor is 400-500 kPa.

4. The method for controlling the valence state of arsenic by oxygen-controlled leaching of arsenic with arsenic sulfide according to claim 1, characterized in that: In step 5, As 5+ The molar ratio of ions to SO2 is 1:1.

3.

5. The method for controlling the valence state of arsenic in arsenic sulfide oxygen-controlled leaching according to claim 1, characterized in that: In step six, the reduced arsenic sulfide leaching solution is cooled and crystallized, and the temperature of the arsenic sulfide leaching solution is below 30°C.

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