Method for arsenic removal and arsenic fixation of high-arsenic soot in copper-lead-zinc smelting and ammonium magnesium arsenate

Abstract

The invention discloses a method for efficiently removing arsenic and fixing arsenic from high-arsenic soot in copper-lead-zinc smelting. The method comprises the following steps: carrying out first-stage normal-pressure alkaline leaching and solid-liquid separation on the high-arsenic soot to obtain first-stage leachate and first-stage leaching residues; the first-stage leaching residues are subjected to second-stage normal-pressure alkaline leaching under the leaching conditions that the concentration of NaOH ranges from 60 g / L to 80 g / L, the concentration of Na2S ranges from 20 g / L to 25 g / L, and second-stage leaching liquid and second-stage leaching residues are obtained through solid-liquid separation; carrying out oxidation treatment on the second-stage leaching solution, and carrying out solid-liquid separation to obtain an oxidized solution; ammonium salt and magnesium salt are added into the oxidized liquid for crystallization and arsenic precipitation, and ammonium magnesium arsenate slag and arsenic precipitation liquid are obtained through solid-liquid separation. The method is suitable for treating the high-arsenic soot in the copper-lead-zinc smelting process, arsenic removal and arsenic fixation of the high-arsenic soot and comprehensive recycling of valuable elements can be achieved, and the method has the advantages of being environmentally friendly, economical, capable of saving energy and high in resource utilization rate.

Description

Technical Field

[0001] The invention relates to the field of arsenic treatment, and in particular to a method for removing arsenic from high-arsenic ash in copper-lead-zinc smelting and fixing arsenic, and magnesium ammonium arsenate. Background Art

[0002] Separating arsenic from high-arsenic fly ash from copper, lead and zinc smelting is one of the current international problems. At present, there are two main methods for removing arsenic from high-arsenic fly ash: pyrolysis and hydrolysis. The principle of arsenic removal by pyrolysis is to use the difference in boiling points between arsenic oxides and other metal oxides at high temperatures to separate arsenic from other metals. It is suitable for materials with high arsenic content in fly ash and non-volatile valuable metals. Wet arsenic removal mainly includes water leaching, acid leaching and alkaline leaching. The principle of water leaching is that arsenic oxides can be dissolved in hot water solutions to remove arsenic. The reaction conditions of this method are mild, but the arsenic leaching rate is not high. The acid leaching method uses sulfuric acid, hydrochloric acid, nitric acid and dirty acid as leaching agents, which can immerse arsenic and other metals into the liquid phase at the same time. This method makes it difficult to separate arsenic from valuable metals. The alkaline leaching method uses alkaline leaching agents to leach arsenic from fly ash into the liquid phase. Commonly used alkaline leaching agents include sodium hydroxide, sodium sulfide, ammonia water, ammonium carbonate, etc. The advantage of alkaline leaching is that it can selectively leach arsenic and avoid the dissolution of a large amount of valuable metals. At the same time, it is conducive to the centralized resource treatment of arsenic in arsenic-rich alkaline leaching solution and the extraction of valuable metals in alkaline leaching residue containing valuable metals.

[0003] The alkali concentration in the alkaline leaching method has a significant effect on the separation of arsenic, and the arsenic separation efficiency increases with the increase of the alkali concentration. Although the arsenic separation efficiency is high at high alkali concentrations, other metals such as Zn, Pb, Sb, etc. will also be leached in large quantities, causing the loss of valuable metals. In addition, as the slurry temperature gradually decreases after filtration, colloidal products such as sodium arsenate, sodium plumbate and sodium zincate are mixed with the leaching residue to form a viscous slurry, which brings difficulties to the filtration of the slurry. Studies have shown that low alkalinity arsenic removal can eliminate the problem of difficult filtration.

[0004] In fact, although alkaline leaching arsenic removal technology has great advantages, how to achieve efficient separation of arsenic in high-alkali solutions is still a problem that restricts its widespread application. In recent years, researchers have proposed new technologies such as ion exchange, membrane separation, and biochemistry. However, these technologies are usually very expensive. Compared with these technologies, chemical precipitation methods that convert dissolved arsenic into low-solubility compounds are widely used because of their low cost. The traditional practice is to add calcium salts and iron salts to arsenic-alkali solutions to produce stable arsenate precipitates. However, due to the co-precipitation of a large amount of hydroxide precipitates with arsenate precipitates, a large amount of alkali will be consumed, producing a large amount of low-grade arsenic slag. However, due to the limitations of reaction conditions, the sulfidation method and the scorodite method require a large amount of acid and cannot achieve alkali recycling. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for removing arsenic and fixing arsenic from high-arsenic fly ash in copper, lead and zinc smelting, and magnesium ammonium arsenate, so as to solve the problems of incomplete arsenic removal from arsenic-containing fly ash and large loss of valuable metals in the existing process.

[0006] In order to achieve the above technical objectives, the technical solution of the present invention is: a method for removing arsenic and fixing arsenic in high-arsenic fly ash in copper, lead and zinc smelting, the method specifically comprising the following steps:

[0007] S1) subjecting the high-arsenic fly ash to a stage of alkaline leaching at normal pressure, and separating the solid from the liquid to obtain a stage of leached residue and a stage of leaching liquid;

[0008] S2) subjecting the first-stage leaching residue obtained in S1) to second-stage atmospheric pressure alkali leaching, and obtaining second-stage leaching residue and second-stage leaching liquid by solid-liquid separation, returning the obtained second-stage leaching residue to the lead smelting system, and returning the second-stage leaching liquid to the first-stage atmospheric pressure alkali leaching;

[0009] S3) adding an oxidant to the second-stage leaching solution obtained in S2) for oxidation treatment, and separating the solid and liquid to obtain an oxidized liquid;

[0010] S4) adding ammonium salt and magnesium salt to the oxidized solution obtained in S3), adjusting the pH of the solution, starting the crystallization arsenic precipitation reaction, and separating the solid and liquid to obtain ammonium arsenate magnesium slag and arsenic precipitation solution, and the arsenic precipitation solution is returned for the second stage normal pressure alkali leaching.

[0011] Further, the leaching conditions in S1) are: NaOH concentration 30-45g / L, Na 2 S concentration is 10-15g / L, reaction temperature is 60-95℃, time is 0.5-1.5h, liquid-solid ratio is 3-7:1.

[0012] Further, the leaching conditions in S2) are: NaOH concentration 60-80g / L, Na 2 S concentration is 20-25g / L, reaction temperature is 60-95℃, time is 1.0-2.0h, liquid-solid ratio is 5-10:1.

[0013] Further, the molar ratio of the oxidant added to the second-stage leaching solution in S3) to the arsenic in the first-stage leaching solution is 2-4:1;

[0014] The oxidant is hydrogen peroxide.

[0015] Further, the amount of ammonium salt added in S3) is NH 4 + :As molar ratio is 4-10:1;

[0016] The amount of magnesium salt added is Mg 2+ :As molar ratio is 1-2:1;

[0017] The initial pH of the crystallization arsenic precipitation reaction is 8-11, and the reaction time is 0.5-1.5h.

[0018] Furthermore, the ammonium salt is any one of ammonium sulfate, ammonium carbonate, ammonium bicarbonate, and ammonium chloride; the magnesium salt is any one of magnesium sulfate, magnesium carbonate, and magnesium chloride.

[0019] Furthermore, in the method, the solid arsenic efficiency is above 97%, and the arsenic grade of the obtained magnesium ammonium arsenate slag is above 25%.

[0020] A magnesium ammonium arsenate is prepared by the above method.

[0021] The present invention mainly relates to the following reaction:

[0022] Alkali leaching process:

[0023] As 2 O 3 +6OH - →2AsO 3 3- +3H 2 O

[0024] MeO+2OH - →MeO 2 2- +H 2 O (MeO represents copper, lead, zinc oxides)

[0025] AsO 3 3- +3S 2- +3H 2 O→AsS 3 3- +6OH -

[0026] MeO 2 2- +S 2- +2H 2 O→MeS↓+4OH -

[0027] Oxidation process:

[0028] AsO 3 3- +H 2 O 2 →AsO 4 3- +H 2 O

[0029] AsS 3 3- +4H 2 O2 →AsO 4 3- +3S↓+4H 2 O

[0030] Arsenic Fixation Process:

[0031] Mg 2+ +2OH - →Mg(OH) 2 ↓

[0032] 3Mg 2+ +2AsO 4 3- +8H 2 O→Mg 3 (AsO 4 ) 2 8H 2 O↓

[0033] Mg 2+ +HAsO 4 2- +H 2 O→MgHAsO 4 ·H 2 O↓

[0034] NH 4 + +Mg 2+ +HnAsO 4 n-3 +6H 2 O→MgNH 4 AsO 4 6H 2 O↓

[0035] Sodium sulfide can not only promote the dissolution and removal of arsenic, but also ensure that the dissolved valuable metals are recovered in the form of sulfide precipitation, thereby avoiding the loss of valuable metals during the arsenic removal process. Compared with the prior art, the technical solution of the present invention has the following beneficial effects: a two-stage alkaline leaching method is used to achieve efficient removal of arsenic in high-arsenic fly ash, with a comprehensive arsenic removal rate of more than 93%, thereby avoiding incomplete arsenic removal under single alkaline leaching conditions and a large loss of valuable metals under high-alkali conditions. In addition, arsenic fixation is directly achieved in an alkaline system through an ammonium magnesium salt arsenic precipitation method, with a solid arsenic efficiency of more than 97%, and the arsenic grade of the obtained ammonium magnesium arsenate slag is more than 25%, which is conducive to storage and landfill. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope of protection of the present invention. In each of the drawings, similar components are numbered similarly.

[0037] Figure 1 This is the XRD spectrum of ammonium magnesium arsenate obtained by solidifying arsenic with ammonium magnesium salt in the embodiment of the present disclosure;

[0038] Figure 2 This is the SEM spectrum of ammonium magnesium arsenate obtained by solidifying arsenic with ammonium magnesium salt in the embodiment of the present disclosure;

[0039] Figure 3 A schematic flow chart of a method for removing arsenic and fixing arsenic from high-arsenic fly ash in copper-lead-zinc smelting provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0041] like Figure 3 As shown, the present invention provides a method for removing arsenic and fixing arsenic from high-arsenic fly ash in copper, lead and zinc smelting, and the method specifically comprises the following steps:

[0042] S1) The high arsenic fly ash is subjected to a normal pressure alkaline leaching, and the leaching conditions are: NaOH concentration 30-45g / L, Na 2 The S concentration is 10-15 g / L, the reaction temperature is 60-95°C, the reaction time is 0.5-1.5 h, the liquid-solid ratio is 3-7:1, and the solid-liquid separation is performed to obtain a first-stage leaching residue and a first-stage leaching liquid;

[0043] S2) subjecting the first-stage leaching residue obtained in step S1) to second-stage normal pressure alkali leaching, wherein the leaching conditions are: NaOH concentration 60-80 g / L, Na 2 The S concentration is 20-25 g / L, the reaction temperature is 60-95°C, the reaction time is 1.0-2.0 h, the liquid-solid ratio is 5-10:1, and the solid-liquid separation is performed to obtain the second-stage leaching residue and the second-stage leaching liquid. The obtained second-stage leaching residue is returned to the lead smelting system, and the second-stage leaching liquid is returned for the first-stage atmospheric pressure alkali leaching;

[0044] S3) adding an oxidant to the first-stage leachate obtained in step S1) for oxidation treatment, and separating the solid and liquid to obtain an oxidized liquid;

[0045] S4) adding ammonium salt and magnesium salt to the oxidized liquid obtained in step S3), adjusting the pH of the solution, starting the crystallization arsenic precipitation reaction, and separating the solid and liquid to obtain ammonium arsenate magnesium slag and arsenic precipitation liquid. The obtained ammonium arsenate magnesium slag can be stored or landfilled, and the arsenic precipitation liquid is returned for the second stage normal pressure alkali leaching.

[0046] Based on the above technical solution, the present invention can also be improved as follows.

[0047] Furthermore, in the method for efficiently removing arsenic and fixing arsenic from high-arsenic fly ash in copper, lead and zinc smelting, in S3), the oxidant added to the first-stage leaching solution is hydrogen peroxide, and the molar ratio of hydrogen peroxide to arsenic in the first-stage leaching solution is 2-4:1.

[0048] Further, in the method for efficiently removing arsenic and fixing arsenic from high-arsenic fly ash in copper, lead and zinc smelting, in step S4), the ammonium salt is any one of ammonium sulfate, ammonium carbonate, ammonium bicarbonate and ammonium chloride, and the magnesium salt is any one of magnesium sulfate, magnesium carbonate and magnesium chloride, wherein NH 4 + :As molar ratio is 4-10:1, Mg 2+ :As molar ratio is 1-2:1.

[0049] Furthermore, in the method for efficiently removing arsenic and fixing arsenic from high-arsenic fly ash in copper, lead and zinc smelting, in S4), the initial pH of the crystallization arsenic precipitation reaction is 8-11, and the reaction time is 0.5-1.5h.

[0050] The technical solution of the present invention is to deal with high-arsenic soot produced in the copper-lead-zinc smelting process, which mainly contains at least one metal among copper, lead and zinc. Arsenic in the high-arsenic soot mainly exists in the form of arsenic oxides, arsenates, arsenic sulfides and elemental arsenic.

[0051] Embodiment 1:

[0052] In this embodiment, the high-arsenic fly ash from lead-zinc smelting contains 39.06% Pb, 21.60% As, 12.09% Zn and 9.89% Sb.

[0053] (1) One-stage leaching: 100 g of high-arsenic fly ash from lead-zinc smelting was subjected to one-stage leaching at normal pressure, with a NaOH concentration of 45 g / L and Na 2 The S concentration is 15g / L, the reaction temperature is 75℃, the reaction time is 1.0h, and the liquid-solid ratio is 6:1. The first-stage leaching residue contains Pb: 52.21%, As: 4.63%, Zn: 16.06%, and Sb: 13.03%. The leaching rates of Pb, As, Zn, and Sb are 0.75%, 84.08%, 1.37%, and 2.18%, respectively.

[0054] (2) Second stage leaching: The first stage leaching residue is subjected to second stage atmospheric pressure leaching, where the NaOH concentration is 80 g / L, Na 2S concentration is 25g / L, reaction temperature is 80℃, reaction time is 1.0h, liquid-solid ratio is 5:1. The second-stage leaching residue contains Pb: 57.71%, As: 1.21%, Zn: 17.74%, Sb: 14.28%. The leaching rates of Pb, As, Zn, and Sb are 0.26%, 76.36%, 0.35%, and 1.14%, respectively.

[0055] (3) Oxidation treatment: hydrogen peroxide is added to the first-stage leaching solution to oxidize trivalent arsenic, wherein the molar ratio of hydrogen peroxide to arsenic in the first-stage leaching solution is 3:1. The composition of the oxidized solution is Pb: 0.43 g / L, As: 30.14 g / L, Zn: 0.25 g / L, Sb: 0.12 g / L.

[0056] (4) Arsenic crystallization: Add ammonium salt and magnesium salt to the oxidized solution (600 mL) for arsenic crystallization. 4 ) 2 SO 4 (NH 4 + :As molar ratio of 4:1) and 89.26 g MgSO 4 7H 2 O(Mg 2+ :As molar ratio was 1.5:1), the solution pH dropped to 9.4, and the reaction was stirred for 0.5h. The arsenic precipitation efficiency reached 97.52%, and the magnesium ammonium arsenate slag (MgNH 4 AsO 4 6H 2 O) Arsenic grade is 30.67%.

[0057] In this embodiment, the comprehensive arsenic leaching rate of the high-arsenic fly ash from lead and zinc smelting is 96.24% after two-stage leaching. Valuable metals such as lead, zinc, and antimony are all enriched in the leaching residue, and the total leaching rate does not exceed 6%. After the first-stage leaching liquid is subjected to oxidation treatment + crystallization arsenic precipitation, the arsenic precipitation rate is as high as 97.52%.

[0058] Embodiment 2:

[0059] In this embodiment, the copper smelting high arsenic fly ash contains As: 22.82%, Zn: 13.47%, Pb: 11.78%, and Cu: 1.95%.

[0060] (1) One-stage leaching: 100 g of copper smelting high-arsenic ash was leached at normal pressure, with a NaOH concentration of 40 g / L and Na 2The S concentration is 15g / L, the reaction temperature is 80℃, the reaction time is 1.0h, and the liquid-solid ratio is 5:1. The first-stage leaching residue contains As: 5.80%, Zn: 18.15%, Pb: 15.93%, and Cu: 2.65%. The leaching rates of As, Zn, Pb, and Cu are 81.34%, 1.14%, 0.78%, and 0.23%, respectively.

[0061] (2) Second stage leaching: The first stage leaching residue is subjected to second stage atmospheric pressure leaching, where the NaOH concentration is 80 g / L, Na 2 The S concentration is 25g / L, the reaction temperature is 80℃, the reaction time is 1.5h, and the liquid-solid ratio is 5:1. The second-stage leaching residue contains As: 1.66%, Zn: 20.00%, Pb: 17.8%, and Cu: 2.93%. The leaching rates of As, Zn, Pb, and Cu are 74.12%, 0.28%, 0.11%, and 0.08%, respectively.

[0062] (3) Oxidation treatment: hydrogen peroxide is added to the first-stage leaching solution to oxidize trivalent arsenic, wherein the molar ratio of hydrogen peroxide to arsenic in the first-stage leaching solution is 4:1. The composition of the oxidized solution is As: 36.94 g / L, Zn: 0.25 g / L, Pb: 0.14 g / L, Cu: 0.005 g / L.

[0063] (4) Arsenic crystallization: Add ammonium salt and magnesium salt to the oxidized solution (500 mL) for arsenic crystallization. Add 116.97 g NH 4 HCO 3 (NH 4 + :As molar ratio of 6:1) and 91.17 g MgSO 4 7H 2 O(Mg 2+ :As molar ratio was 1.5:1), the solution pH dropped to 10.2, and the reaction was stirred for 1.0h. The arsenic precipitation efficiency reached 98.49%, and the magnesium ammonium arsenate slag (MgNH 4 AsO 4 6H 2 O) Arsenic grade is 30.56%.

[0064] In this embodiment, the comprehensive arsenic leaching rate of the copper smelting high-arsenic fly ash after two-stage leaching is 95.17%, and valuable metals such as lead, zinc, and antimony are all enriched in the leaching residue. The total leaching rate does not exceed 5%. After the first-stage leaching liquid is subjected to oxidation treatment + crystallization arsenic precipitation, the arsenic precipitation rate is as high as 98.49%.

[0065] Embodiment 3:

[0066] In this embodiment, the high-arsenic fly ash from lead-zinc smelting contains As: 19.15%, Pb: 15.11%, Sb: 5.98%, and Zn: 3.15%.

[0067] (1) One-stage leaching: 100 g of high-arsenic fly ash from lead-zinc smelting was subjected to one-stage leaching at normal pressure, with a NaOH concentration of 35 g / L and Na 2 The S concentration is 10g / L, the reaction temperature is 80℃, the reaction time is 1.5h, and the liquid-solid ratio is 7:1. The first-stage leaching residue contains 4.94% As, 17.70% Pb, 6.93% Sb, and 3.68% Zn. The leaching rates of As, Pb, Sb, and Zn are 78.16%, 0.85%, 1.92%, and 1.18%, respectively.

[0068] (2) Second stage leaching: The first stage leaching residue was subjected to second stage atmospheric pressure leaching, where the NaOH concentration was 70 g / L and Na 2 The S concentration is 20g / L, the reaction temperature is 85℃, the reaction time is 1.0h, and the liquid-solid ratio is 6:1. The second-stage leaching residue contains As: 1.33%, Pb: 18.58%, Sb: 7.19%, and Zn: 3.86%. The leaching rates of As, Pb, Sb, and Zn are 74.37%, 0.28%, 1.37%, and 0.26%, respectively.

[0069] (3) Oxidation treatment: hydrogen peroxide was added to the first-stage leaching solution to oxidize trivalent arsenic, wherein the molar ratio of hydrogen peroxide to arsenic in the first-stage leaching solution was 3.5:1. The composition of the oxidized solution was As: 21.14 g / L, Pb: 0.11 g / L, Sb: 0.08 g / L, and Zn: 0.02 g / L.

[0070] (4) Arsenic crystallization: Add ammonium salt and magnesium salt to the oxidized solution (700 mL) for arsenic crystallization. Add 75.94 g (NH 4 ) 2 CO 3 (NH 4 + :As molar ratio of 8:1) and 24.99 g MgCO 3 (Mg 2+ :As molar ratio was 1.5:1), the solution pH dropped to 9.7, and the reaction was stirred for 1.0h. The arsenic precipitation efficiency reached 99.34%, and the magnesium ammonium arsenate slag (MgNH 4 AsO 4 6H 2 O) Arsenic grade is 29.57%.

[0071] In this embodiment, the comprehensive arsenic leaching rate of the lead smelting high-arsenic fly ash after two-stage leaching is 94.40%, and valuable metals such as lead, antimony, and zinc are all enriched in the leaching residue. The total leaching rate does not exceed 6%. After the first-stage leaching liquid is subjected to oxidation treatment + crystallization arsenic precipitation, the arsenic precipitation rate is as high as 99.34%.

[0072] Embodiment 4:

[0073] In this embodiment, the high-arsenic fly ash from lead-zinc smelting contains 41.70% Pb, 12.36% As, 9.55% Sb and 4.26% Zn.

[0074] (1) One-stage leaching: 100 g of high-arsenic fly ash from lead-zinc smelting was subjected to one-stage leaching at normal pressure, with a NaOH concentration of 30 g / L and Na 2 The S concentration is 15g / L, the reaction temperature is 95℃, the reaction time is 1.5h, and the liquid-solid ratio is 7:1. The first-stage leaching residue contains 48.32% Pb, 3.39% As, 10.93% Sb, and 4.96% Zn. The leaching rates of Pb, As, Sb, and Zn are 0.67%, 76.46%, 1.90%, and 0.28%, respectively.

[0075] (2) Second stage leaching: The first stage leaching residue is subjected to second stage atmospheric pressure leaching, where the NaOH concentration is 60 g / L and Na 2 The S concentration is 25g / L, the reaction temperature is 95℃, the reaction time is 1.5h, and the liquid-solid ratio is 7:1. The second-stage leaching residue contains 50.94% Pb, 1.06% As, 11.40% Sb, and 5.22% Zn. The leaching rates of Pb, As, Sb, and Zn are 0.12%, 70.43%, 1.16%, and 0.11%, respectively.

[0076] (3) Oxidation treatment: hydrogen peroxide is added to the first-stage leaching solution to oxidize trivalent arsenic, wherein the molar ratio of hydrogen peroxide to arsenic in the first-stage leaching solution is 2:1. The composition of the oxidized solution is Pb: 0.34 g / L, As: 13.38 g / L, Sb: 0.08 g / L, and Zn: 0.01 g / L.

[0077] (4) Arsenic crystallization: Add ammonium salt and magnesium salt to the oxidized solution (700 mL) for arsenic crystallization. Add 66.89 g NH 4 Cl(NH 4 + :As molar ratio of 10:1) and 17.86 g MgCl 2 (Mg 2+ :As molar ratio was 1.5:1), the solution pH dropped to 9.8, and the reaction was stirred for 1.5 hours. The arsenic precipitation efficiency reached 99.91%, and the magnesium ammonium arsenate slag (MgNH 4 AsO 4 6H 2 O) Arsenic grade is 27.08%.

[0078] In this embodiment, the comprehensive arsenic leaching rate of the high-arsenic fly ash from lead and zinc smelting is 93.04% after two-stage leaching. Valuable metals such as lead, zinc, and antimony are all enriched in the leaching residue, and the total leaching rate does not exceed 5%. After the first-stage leaching liquid is subjected to oxidation treatment + crystallization arsenic precipitation, the arsenic precipitation rate is as high as 99.91%.

[0079] The XRD spectrum of ammonium magnesium arsenate obtained by solidifying arsenic with ammonium magnesium salt in the above embodiment is as follows: Figure 1 As shown; the SEM spectrum of ammonium magnesium arsenate obtained by solid arsenic with ammonium magnesium salt, as shown Figure 2 shown.

[0080] The embodiments of the present application provide a method for removing arsenic and fixing arsenic from high-arsenic fly ash in copper, lead and zinc smelting, and magnesium ammonium arsenate, which are introduced in detail. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application; at the same time, for those of ordinary skill in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present application.

[0081] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" and "comprising" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problems within a preset error range and basically achieve the technical effects. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be subject to that defined in the attached claims.

[0082] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0083] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0084] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the scope of protection of the claims attached to the present application.

Claims

1. A method for efficiently removing arsenic and fixing arsenic from high-arsenic fly ash in copper, lead and zinc smelting, characterized in that: The method specifically comprises the following steps: S1) subjecting the high-arsenic fly ash to a stage of alkaline leaching at normal pressure, and separating the solid and liquid to obtain a stage of leached residue and a stage of leaching liquid; S2) subjecting the first-stage leaching residue obtained in S1) to second-stage atmospheric pressure alkali leaching, and obtaining second-stage leaching residue and second-stage leaching liquid by solid-liquid separation, returning the obtained second-stage leaching residue to the lead smelting system, and returning the second-stage leaching liquid to the first-stage atmospheric pressure alkali leaching; S3) adding an oxidant to the second-stage leaching solution obtained in S2) for oxidation treatment, and separating the solid and liquid to obtain an oxidized liquid; S4) adding ammonium salt and magnesium salt to the oxidized solution obtained in S3), adjusting the pH of the solution, starting the crystallization arsenic precipitation reaction, and separating the solid and liquid to obtain ammonium arsenate magnesium slag and arsenic precipitation solution, and the arsenic precipitation solution is returned for the second stage normal pressure alkali leaching.

2. The method according to claim 1, characterized in that The leaching conditions in S1) are: NaOH concentration 30-45 g / L, Na2S concentration 10-15 g / L, reaction temperature 60-95°C, time 0.5-1.5 h, and liquid-to-solid ratio 3-7:

1.

3. The method according to claim 1, characterized in that The leaching conditions in S2) are: NaOH concentration 60-80 g / L, Na2S concentration 20-25 g / L, reaction temperature 60-95°C, time 1.0-2.0 h, and liquid-to-solid ratio 5-10:

1.

4. The method according to claim 1, characterized in that: The molar ratio of the oxidant added to the second-stage leaching solution in S3) to the arsenic in the first-stage leaching solution is 2-4:1; The oxidant is hydrogen peroxide.

5. The method according to claim 1, characterized in that The amount of ammonium salt added in S3) is NH4 + :As molar ratio is 4-10:1; The amount of magnesium salt added is Mg 2+ :As molar ratio is 1-2:1; The initial pH of the crystallization arsenic precipitation reaction is 8-11, and the reaction time is 0.5-1.5h.

6. The method according to claim 5, characterized in that The ammonium salt is any one of ammonium sulfate, ammonium carbonate, ammonium bicarbonate and ammonium chloride; the magnesium salt is any one of magnesium sulfate, magnesium carbonate and magnesium chloride.

7. The method according to claim 1, characterized in that In the method, the solid arsenic efficiency is above 97%, and the arsenic grade of the obtained magnesium ammonium arsenate slag is above 25%.

8. A magnesium ammonium arsenate, characterized in that The magnesium ammonium arsenate is prepared by the method according to any one of claims 1 to 7.

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