Arsenic removal method for high-arsenic zinc oxide smoke dust

Abstract

The invention relates to a high-arsenic zinc oxide smoke dust arsenic removal method which comprises the following steps: 1) copper recovery: adding a predetermined amount of a copper removal agent into a stirring tank filled with zinc oxide smoke dust pickle liquor, stirring and reacting for 30-60 minutes, and performing solid-liquid separation to obtain copper sludge and copper removal filtrate; (2) arsenic separation: the copper-removed filtrate enters an oxidation reaction stirring tank, ferric salt and an oxidizing agent are sequentially added for precipitation and arsenic removal, the stirring speed is controlled to be 200-400 r / min, the reaction temperature is 75-85 DEG C, and iron arsenate precipitation and arsenic-removed liquid are obtained through solid-liquid separation. According to the zinc oxide smoke dust arsenic removal treatment process, rapid separation of copper ions, zinc ions and arsenic ions is achieved, arsenic is stably removed, meanwhile, loss of the zinc ions is greatly reduced, used chemicals are low in price and easy to obtain, used equipment is conventional devices, and the process is simple, safe, efficient, small in energy consumption and low in cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of lead-zinc smelting, and particularly relates to a method for removing arsenic from high-arsenic zinc oxide fume and dust. Background Art

[0002] The zinc oxide fume and dust generated during the roasting process of lead-zinc concentrate is rich in various valuable elements such as lead, zinc, silver, germanium, and indium. It is an important secondary resource in the smelting process and can be comprehensively recycled to enhance the utilization value of mineral resources. With the rapid development of lead-zinc smelting in China, the shortage of high-quality lead-zinc resources has led to the exploitation and utilization of a large number of low-grade and complex ores. The arsenic content in the raw ore has been increasing continuously. During the high-temperature smelting process, part of the arsenic enters the zinc oxide fume and dust with the flue gas, forming high-arsenic zinc oxide fume and dust. If these arsenic-containing fume and dust are directly returned to the lead-zinc smelting process, it will affect the production efficiency, reduce the product grade, and cause the entire smelting process to malfunction. Therefore, it is of great significance to study the arsenic removal technology for high-arsenic zinc oxide fume and dust and improve the comprehensive recycling value of the fume and dust.

[0003] At present, the arsenic removal processes for zinc oxide fume and dust mainly include pyrometallurgical arsenic removal and hydrometallurgical arsenic removal. Pyrometallurgical arsenic removal refers to volatilizing arsenic in the form of As2O3 at high temperature and then recovering the fume and dust. However, the arsenic removal rate of pyrometallurgical arsenic removal is low, and it is easy to cause secondary pollution. During the arsenic removal process, a large amount of metals such as zinc and lead will also escape, resulting in the loss of valuable metals. Hydrometallurgical arsenic removal includes the alkali method arsenic removal process and the acid method arsenic removal process. The alkali method arsenic removal mainly uses sodium hydroxide solution to leach the arsenic-containing oxides in the fume and dust to convert them into sodium arsenate and enter the solution, thereby achieving effective arsenic removal. However, the raw material cost of sodium hydroxide is relatively high, and the reaction time is too long. The acid method arsenic removal process mainly uses an acidic solution for leaching and removes arsenic through forms such as iron arsenate precipitation. In the prior art, the following two methods are the most widely used:

[0004] (1) Under acidic conditions, arsenic is precipitated and removed in the form of well-crystallized scorodite. However, this method needs to be carried out in high-pressure equipment, and there are problems such as large equipment investment and high operating costs;

[0005] (2) In an atmospheric pressure container, iron ions are added to form iron arsenate precipitation for arsenic removal. However, its process conditions are strict, the pH value of the obtained precipitation is relatively high, a large amount of lime needs to be added, resulting in a large amount of arsenic-containing waste residue and a large loss of zinc in the leaching solution.

[0006] To solve the problems such as low arsenic removal rate and excessive loss of zinc metal when treating high-arsenic zinc oxide fume and dust by the acid method, a low-cost and high-efficiency arsenic removal process is urgently needed. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for removing arsenic from high-arsenic zinc oxide fume and dust to minimize the loss rate of zinc and ensure the recycling value of zinc oxide fume and dust.

[0008] The present invention provides a method for arsenic removal from high-arsenic zinc oxide fume, comprising the following steps:

[0009] Step 1), copper recovery:

[0010] Add a predetermined amount of copper-removing agent to a stirring tank containing the acid leaching solution of zinc oxide fume. After stirring and reacting for 30 - 60 min, through solid-liquid separation, copper mud and copper-removed filtrate are obtained.

[0011] Step 2), arsenic separation:

[0012] The copper-removed filtrate enters an oxidation reaction stirring tank, and iron salt and oxidant are added in sequence for arsenic precipitation removal. Control the stirring speed at 200 - 400 r / min and the reaction temperature at 75 - 85 °C. Through solid-liquid separation, iron arsenate precipitate and arsenic-removed liquid are obtained.

[0013] Furthermore, the method further comprises:

[0014] Step 3), filter pressing and washing the iron arsenate precipitate to obtain arsenic residue and washing solution. The washing solution is combined with the arsenic-removed liquid and returned to roasting ore leaching.

[0015] Furthermore, in Step 1), the Cu content in the acid leaching solution of zinc oxide fume is higher than 300 mg / L.

[0016] Furthermore, the copper-removing agent in Step 1) is iron powder.

[0017] Furthermore, the iron salt in Step 2) is selected from one or more of ferric chloride, ferrous sulfate, ferric sulfate, and polyferric sulfate.

[0018] Furthermore, the oxidant in Step 2) is selected from one or more of air, hydrogen peroxide, ozone, and potassium permanganate.

[0019] Furthermore, in Step 3), the temperature of the water for filter pressing and washing is 70 - 80 °C, and the number of washing times is 2 - 4 times.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1) The arsenic removal treatment process for zinc oxide fume provided by the present invention realizes the rapid separation of copper, zinc, and arsenic ions, and while stably removing arsenic, greatly reduces the loss of zinc ions.

[0022] 2) The arsenic removal treatment process for zinc oxide fume provided by the present invention uses inexpensive and easily available agents, and all the equipment used is conventional equipment. The process is simple, safe and efficient, with low energy consumption and low cost, and is easy to be industrially promoted. Description of the Drawings

[0023] Figure 1This is a flow chart of a method for removing arsenic from high-arsenic zinc oxide fume dust of the present invention. Specific embodiments

[0024] The present invention will be described in detail below in conjunction with the embodiments shown in the accompanying drawings. It should be noted, however, that these embodiments do not limit the present invention. Any equivalent transformation or substitution in terms of function, method, or structure made by those of ordinary skill in the art based on these embodiments shall fall within the protection scope of the present invention.

[0025] Refer Figure 1 As shown, this embodiment provides a method for removing arsenic from high-arsenic zinc oxide fume dust, aiming to generate crystalline ferric arsenate precipitate for arsenic removal by adding iron salts and oxidants under acidic conditions in a high-temperature and normal-pressure container, and then through pressure filtration and washing to minimize the loss rate of zinc and ensure the recycling value of zinc oxide fume dust. The specific steps are as follows:

[0026] Step 1), copper recovery:

[0027] A predetermined amount of copper-removing agent is added to the stirring tank containing the acid leaching solution of zinc oxide fume dust. After stirring and reacting for 30 - 60 minutes, solid-liquid separation is carried out to obtain copper mud and copper-removed filtrate.

[0028] Step 2), arsenic separation:

[0029] The copper-removed filtrate enters the oxidation reaction stirring tank, and iron salts and oxidants are added in sequence for arsenic precipitation removal. The stirring speed is controlled at 200 - 400 r / min, and the reaction temperature is 75 - 85 °C. After solid-liquid separation, ferric arsenate precipitate and arsenic-removed solution are obtained.

[0030] Step 3), pressure filtration and washing of the ferric arsenate precipitate are carried out to obtain arsenic residue and washing solution. The washing solution is combined with the arsenic-removed solution and returned to roast ore leaching. It is found that a large amount of zinc sulfate crystals precipitate during the separation process of the ferric arsenate precipitate in step 2), and zinc loss can be effectively reduced through pressure filtration and washing.

[0031] In this embodiment, the Cu content in the acid leaching solution of zinc oxide fume dust in step 1) is higher than 300 mg / L.

[0032] In this embodiment, the copper-removing agent in step 1) is iron powder.

[0033] In this embodiment, the iron salts in step 2) are selected from one or more of ferric chloride, ferrous sulfate, ferric sulfate, and polyferric sulfate.

[0034] In this embodiment, the oxidants in step 2) are selected from one or more of air, hydrogen peroxide, ozone, and potassium permanganate.

[0035] In this embodiment, the temperature of the pressure filtration washing water in step 3) is 70-80°C, and the number of washing times is 2-4 times.

[0036] In this embodiment, the addition amounts of iron salt and oxidant and the treatment time are not particularly limited and can be determined according to the best arsenic separation efficiency. In an embodiment of the present invention, the iron-to-arsenic molar ratio is 1, and the reaction time is 30 min.

[0037] Example 1:

[0038] The present invention provides a process for removing arsenic from high-arsenic zinc oxide fume. The experimental raw material is the acid leaching solution after recovering valuable metals such as indium from zinc oxide fume in a lead-zinc smelter in Inner Mongolia Autonomous Region. Its main components (%) are: Zn 14.71, As 1.40, Cu 0.12, Ge 0.008, Sb 0.01, Mn 0.28, Mg 1.31, Cd 0.30, SiO2 26.91, F - 53.53. It can be seen that this solution is a typical acid leaching solution of high-arsenic zinc oxide fume. In addition, its Cu content is 0.12%, which has a certain recovery value.

[0039] The specific test steps are as follows:

[0040] 1) Add iron powder to the acid leaching solution of zinc oxide fume, with a dosage of 2 g / L. After stirring and reacting for 30 min, solid-liquid separation is carried out to obtain copper mud and copper-removed solution.

[0041] 2) To the copper-removed filtrate, ferric sulfate (dosage of 18 g / L) and hydrogen peroxide (dosage of 27 g / L) are added in sequence for arsenic precipitation. The reaction temperature is controlled at 80°C, and stirring reaction is carried out at a rotation speed of 200 r / min for 30 min. After solid-liquid separation, ferric arsenate crystal precipitation and arsenic-removed solution are obtained.

[0042] 3) Use 70°C clear water to carry out pressure filtration washing on the ferric arsenate precipitation three times to obtain arsenic slag and cleaning solution. The latter is combined with the arsenic-removed solution and returned to roasting ore leaching. (See Table 1 for test analysis data)

[0043] Table 1 Test analysis data

[0044] Sample Name Cu (mg / L) Zn (%) As (%) <![CDATA[The slag amount (kg / m 3 )]]> Acid Leaching Solution of Zinc Oxide Fume 1214 14.71 1.42 / Copper-Removed Filtrate 0.126 14.33 1.50 / Arsenic-Removed Solution 0.105 14.75 0.27 / Washing Solution 1 at 70°C / 4.47 0.092 / Washing Solution 2 at 70°C / 1.69 0.035 / Washing Solution 3 at 70°C / 0.30 0.0075 / Copper Sludge 57.30 2.40 9.96 2.05 Arsenic Residue 0.016 4.19 35.22 30.65

[0045] It can be seen from the results in Table 1 that the copper recovery rate can reach over 99%, the copper grade in the copper mud is 57%, and the output is 2.05 kg / m 3 ; the arsenic removal rate is 81%, the amount of arsenic slag is 30.65 kg / m 3 , and the zinc loss rate is 0.91%.

[0046] Perform a toxicity leaching test on the arsenic slag precipitation (see Table 2 for the analysis data of the toxicity leaching of the precipitate).

[0047] Table 2 Analysis data of the toxicity leaching of the precipitate

[0048] Sample Name Unit Zn Cd As Toxicity Leaching of Arsenic Residue mg / L 0.883 0.056 1.82 GB5085.3 - 2007 mg / L ＜100 ＜1 ＜5

[0049] As can be seen from the results in Table 2, the arsenic residue generated in this embodiment meets the "National Hazardous Waste Identification Standard GB5085.1-2007".

[0050] Example 2:

[0051] The present invention provides a process for removing arsenic from high-arsenic zinc oxide fume. The experimental raw material is the acid leaching solution after recovering valuable metals such as indium from zinc oxide fume in a lead-zinc smelter in Inner Mongolia Autonomous Region. Its main components (%) are: Zn 15.99, As 0.61, Cu 0.01, Ge 0.0048, Sb 0.0058, Mn 0.27, Mg 1.30, Cd 0.29, SO4 2- 30.66. It can be seen that the content of Cu in this solution is relatively low, so copper recovery is abandoned in the experiment and zinc-arsenic separation is directly carried out.

[0052] The specific test steps are as follows:

[0053] 1) Ferric sulfate (dosage: 27.5 g / L) and potassium permanganate (dosage: 3.3 g / L) are successively added to the acid leaching solution of zinc oxide fume for arsenic precipitation removal. The reaction temperature is controlled at 80 °C, and the mixture is stirred at a speed of 200 r / min for 30 min. After solid-liquid separation, ferric arsenate crystal precipitate and arsenic-removed solution are obtained;

[0054] 2) The ferric arsenate precipitate is pressure-filtered and washed three times with water at 70 °C to obtain arsenic residue and washing solution. The latter is combined with the arsenic-removed solution and returned to roast ore leaching. (See Table 3 for test analysis data)

[0055] Table 3 Test analysis data

[0056] Sample Name Zn (%) As (%) <![CDATA[The amount of slag (kg / m 3 )]]> Acid Leaching Solution of Zinc Oxide Fume 15.99 0.86 / Arsenic-Removed Solution 16.56 0.23 / Washing Solution 1 at 70°C 5.38 0.087 Washing Solution 2 at 70°C 1.95 0.031 Washing Solution 3 at 70°C 0.21 0.0095 2.05 Arsenic Residue 5.81 29.44 23.45

[0057] Calculated according to the test results in Table 3: the zinc loss rate is 0.82%; the arsenic removal rate is about 80%, and the amount of arsenic residue is 23.45 kg / m 3 .

[0058] A toxicity leaching test is carried out on the arsenic residue precipitate (see Table 4 for the analysis data of the toxicity leaching of the precipitate).

[0059] Table 4 Analysis data of the toxicity leaching of the precipitate

[0060] Sample Name Unit Zn Cd As Toxicity Leaching of Arsenic Residue mg / L 0.384 0.040 1.41 GB5085.3 - 2007 mg / L ＜100 ＜1 ＜5

[0061] As can be seen from the results in Table 4, the arsenic residue generated in this embodiment complies with the "GB5085.1-200 National Hazardous Waste Identification Standard".

[0062] The arsenic removal method for high-arsenic zinc oxide fume has the following technical effects:

[0063] 1) The arsenic removal treatment process for zinc oxide fume provided by the present invention realizes the rapid separation of copper, zinc, and arsenic ions, and while stably removing arsenic, greatly reduces the loss of zinc ions.

[0064] 2) The arsenic removal treatment process for zinc oxide fume provided by the present invention uses inexpensive and easily available reagents, and the equipment used is all conventional devices. The process is simple, safe and efficient, with low energy consumption and low cost, and is easy to be promoted industrially.

[0065] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

Claims

1. A method for arsenic removal from high-arsenic zinc oxide fume, characterized in that It includes the following steps: Step 1), copper recovery: Add a predetermined amount of copper removal agent to the stirring tank containing the acid leaching solution of zinc oxide dust. After stirring and reacting for 30 - 60 min, through solid-liquid separation, copper mud and copper removal filtrate are obtained; Step 2), arsenic separation: The copper removal filtrate enters the oxidation reaction stirring tank, and iron salt and oxidant are added in sequence for arsenic precipitation removal. Control the stirring speed at 200 - 400 r / min and the reaction temperature at 75 - 85 °C. Through solid-liquid separation, iron arsenate precipitate and post-arsenic-removal solution are obtained.

2. The method for arsenic removal from high-arsenic zinc oxide fume according to claim 1, characterized in that, It also includes: Step 3), filter pressing and washing the iron arsenate precipitate to obtain arsenic residue and cleaning solution. The cleaning solution is combined with the post-arsenic-removal solution and returned to roast ore leaching.

3. The method for arsenic removal from high-arsenic zinc oxide fume according to claim 1, wherein, In the acid leaching solution of zinc oxide dust described in Step 1), the Cu content is higher than 300 mg / L.

4. The method for arsenic removal from high-arsenic zinc oxide fume according to claim 3, characterized in that, The copper removal agent described in Step 1) is iron powder.

5. The method for arsenic removal from high-arsenic zinc oxide fume according to claim 1, characterized in that, The iron salt described in Step 2) is selected from one or more of ferric chloride, ferrous sulfate, ferric sulfate, and polyferric sulfate.

6. The method for arsenic removal from high-arsenic zinc oxide fume according to claim 5, characterized in that, The oxidant described in Step 2) is selected from one or more of air, hydrogen peroxide, ozone, and potassium permanganate.

7. The method for arsenic removal from high-arsenic zinc oxide fume according to claim 1, characterized in that, In Step 3), the temperature of the water for filter pressing and washing is 70 - 80 °C, and the number of washing times is 2 - 4 times.

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