Arsenic removal method for high-arsenic lead anode slime

Abstract

The invention relates to a method for removing arsenic from high-arsenic lead anode slime, and belongs to the technical field of metallurgy. The method comprises the following steps that (1) the high-arsenic lead anode slime is placed in air to be naturally oxidized for not less than 30 days at the room temperature, or air is adopted for pre-oxidation, and oxidized high-arsenic lead anode slime is obtained; and (2) roasting the oxidized high-arsenic lead anode slime in a nitrogen atmosphere or a nitrogen-oxygen mixed gas atmosphere to remove arsenic, so as to obtain the roasted high-arsenic lead anode slime. According to the method, for the high-arsenic lead anode slime, after the high-arsenic lead anode slime is oxidized, roasting arsenic removal is conducted in the nitrogen atmosphere or the nitrogen-oxygen mixed gas atmosphere, arsenic can be effectively removed, meanwhile, antimony and bismuth are prevented from being volatilized into smoke dust, and the method is short in process and easy and convenient to operate.

Description

Technical Field

[0001] The present application relates to the field of metallurgical technology, and in particular to a method for removing arsenic from high-arsenic lead anode mud. Background Art

[0002] Lead anode mud is a byproduct of the lead electrolytic refining process, and its main components include Au, Ag, Se, Te, Pb, Cu, As, Sb, Bi, etc. As As has a great influence on the treatment process of lead anode mud, lead anode mud is usually divided into high arsenic lead anode mud and low arsenic lead anode mud according to the As content in the lead anode mud. There are a lot of reports on the treatment of low arsenic lead anode mud at home and abroad, and both the pyrometallurgical and hydrometallurgical treatment processes are relatively mature. If the traditional low arsenic lead anode mud treatment process is used to treat high arsenic lead anode mud, arsenic is distributed in various intermediate links of the process, which not only causes environmental pollution, but also arsenic cannot be reasonably recovered. The adverse effects of arsenic are mainly that it is scattered during the smelting process, causing pollution and difficult to separate from antimony. Therefore, high arsenic lead anode mud must be pretreated to convert it into low arsenic lead anode mud before treatment.

[0003] In recent years, a lot of work has been done on the pretreatment process of high-arsenic lead anode mud, and many results have been achieved. At present, the pretreatment arsenic removal processes of high-arsenic lead anode mud mainly include pyrometallurgical arsenic removal process, hydrometallurgical arsenic removal process, and pyrometallurgical-hydrometallurgical combined arsenic removal process.

[0004] At present, the main methods of pyrometallurgical dearsenication include oxidation roasting, reduction roasting, vacuum dearsenication and smelting dearsenication. Pyrometallurgical dearsenication is a mature and commonly used method for anode mud dearsenication. It has the advantages of strong raw material adaptability and large processing capacity, but it has problems such as low dearsenication rate, poor working environment and serious environmental pollution.

[0005] Wet arsenic removal can be divided into hot water leaching arsenic removal, acid leaching arsenic removal, and alkaline leaching arsenic removal according to different leaching systems. The arsenic leaching rate of high-arsenic lead anode mud treated by wet method is relatively high, and arsenic can be effectively removed. It has received much attention in recent years. However, there are many problems in the wet process, such as large leaching liquid processing volume, long process, multiple steps, difficult separation, and complex recycling of valuable elements such as arsenic. And because it consumes a large amount of raw materials used for leaching, the cost is high, and it is difficult to apply to the pretreatment of high-arsenic lead anode mud.

[0006] The pyrometallurgical-wet arsenic removal process mainly converts arsenic into easily leached salts through a pretreatment process, and then uses wet leaching to make the arsenic enter the leachate. This type of process combines the advantages of pyrometallurgical and wet leaching, with strong raw material adaptability and high arsenic removal rate, but the process is long and there are many arsenic dispersion links, which is not conducive to the solidification treatment of arsenic.

[0007] For those skilled in the art, how to provide a treatment process with short flow, simple operation and good efficiency for high-arsenic lead anode mud, while removing arsenic to the maximum extent possible and limiting the volatilization of antimony and bismuth into the smoke as much as possible, so as to achieve effective separation of arsenic from antimony and bismuth has always been a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0008] In order to solve or partially solve the problems existing in the related art, the present application provides a method for removing arsenic from high-arsenic lead anode mud. For the method, the high-arsenic lead anode mud is first oxidized and then roasted in a nitrogen atmosphere or in a nitrogen-oxygen mixed gas atmosphere to remove arsenic, thereby effectively removing arsenic and limiting the volatilization of antimony and bismuth into smoke. The method has a short process and is easy to operate.

[0009] A method for removing arsenic from high-arsenic lead anode mud in the present application comprises the following steps:

[0010] (1) placing the high-arsenic lead anode mud in air at room temperature for natural oxidation for not less than 30 days or pre-oxidizing with air to obtain oxidized high-arsenic lead anode mud;

[0011] The specific operation of pre-oxidation with air is as follows: air flow rate is 0.15-1L / min, pre-oxidation temperature is 300-350°C, and pre-oxidation time is 1-3h;

[0012] (2) roasting the oxidized high-arsenic lead anode mud in a nitrogen atmosphere or in a nitrogen-oxygen mixed gas atmosphere to remove arsenic, thereby obtaining roasted high-arsenic lead anode mud;

[0013] The nitrogen-oxygen mixed gas atmosphere is a mixed gas of nitrogen and oxygen, and the volume ratio of nitrogen in the mixed gas is 95%;

[0014] The high-arsenic lead anode mud has an arsenic mass fraction greater than or equal to 30wt%, and an antimony mass fraction greater than or equal to 25wt%.

[0015] Furthermore, in order to further remove arsenic from the roasted high-arsenic lead anode mud obtained after the preliminary arsenic removal treatment, the present application also provides a better arsenic removal method, which, on the basis of the preliminary arsenic removal treatment, further comprises the step of performing reduction roasting and arsenic removal on the roasted high-arsenic lead anode mud in a N2-CO atmosphere, and the arsenic-removed lead anode mud is obtained after the reduction roasting and arsenic removal;

[0016] The specific operation of reducing and roasting to remove arsenic in N2-CO atmosphere is as follows: the volume ratio of CO in the N2-CO mixed gas is 5%, the flow rate of the N2-CO mixed gas is 0.5L / min, the roasting temperature is 650-700°C, and the roasting time is 2-3h.

[0017] Furthermore, the specific operation of reducing and roasting to remove arsenic in a N2-CO atmosphere is as follows: the volume concentration of CO in the N2-CO mixed gas is 5%, the flow rate of the N2-CO mixed gas is 0.5 L / min, the roasting temperature is 700°C, and the roasting time is 3 h.

[0018] Furthermore, the natural oxidation time is not less than 60 days.

[0019] Furthermore, the specific operation of pre-oxidation using air is: the pre-oxidation air flow rate is 0.5 L / min, the pre-oxidation temperature is 300° C., and the pre-oxidation time is 1 h.

[0020] Furthermore, the specific operation of calcining and removing arsenic in a nitrogen atmosphere is: calcining temperature is 450-600° C., nitrogen flow rate is 0.5 L / min, and calcining time is 0.5-3 h.

[0021] Furthermore, the specific operation of calcining and removing arsenic in a nitrogen atmosphere is: calcining temperature is 600° C., nitrogen flow rate is 0.5 L / min, and calcining time is 0.5 h.

[0022] Compared with the prior art, the beneficial effects of this application are:

[0023] 1. Using fresh high-arsenic lead anode mud as raw material, the "natural oxidation-roasting dearsenification" or "air low-temperature pre-oxidation-roasting dearsenification" process can achieve effective separation of arsenic and antimony and bismuth. Under the conditions of pre-oxidation temperature of 300℃ and pre-oxidation time of 1h, the arsenic removal rate can reach more than 80%, and the antimony volatilization rate is about 10%. Under the condition of natural oxidation days of 60 days, the arsenic removal rate is 82.14% and the antimony volatilization rate is 13.23%.

[0024] 2. For high-arsenic lead anode mud, the present application can effectively remove arsenic by first oxidizing the high-arsenic lead anode mud and then roasting it in a nitrogen atmosphere or in a nitrogen-oxygen mixed gas atmosphere to remove arsenic, while limiting the volatilization of antimony and bismuth into smoke. The method has a short process, simple operation and low process cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects, features and advantages of the present application will become more apparent through a more detailed description of exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0026] Figure 1 Schematic diagram of the appearance of lead anode mud before roasting at different natural oxidation days in Example 1;

[0027] Figure 2 Schematic diagram of the appearance of lead anode mud after roasting for different natural oxidation days in Example 1;

[0028] Figure 3 is a schematic diagram of the appearance of the baked sand after volatilization and roasting under nitrogen and air atmospheres in Example 2;

[0029] Figure 4 is a schematic diagram of the appearance of roasted sand after arsenic removal by roasting under different air pre-oxidation conditions in Example 3;

[0030] Figure 5 is a schematic diagram of the appearance of roasted sand after roasting at different pre-oxidation air flow rates in Example 3;

[0031] Figure 6 This is a schematic diagram of the appearance of the high-arsenic lead anode mud before roasting in Example 4;

[0032] Figure 7 This is a schematic diagram of the appearance of different amounts of high-arsenic lead anode mud after roasting in Example 4;

[0033] Figure 8 This is a schematic diagram of the appearance of 1000.00 g of melted high-arsenic lead anode mud in Example 4. DETAILED DESCRIPTION

[0034] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0035] Example 1

[0036] The method for removing arsenic from high-arsenic lead anode mud in this embodiment comprises the following steps:

[0037] (1) Five groups of high-arsenic lead anode mud, each containing 20 g, were placed in air for natural oxidation at room temperature, and the corresponding natural oxidation days for each group were 0 days, 15 days, 30 days, and 60 days, respectively, to obtain oxidized high-arsenic lead anode mud;

[0038] The high-arsenic lead anode mud was collected from a fresh high-arsenic lead anode mud sample from a smelter in Yunnan. It was gray-black and blocky in appearance. Its water content was 11.24% after vacuum drying. Its main chemical components are shown in Table 1.

[0039] Table 1 Main chemical components of high arsenic lead anode mud

[0040] Element content(%) Element content(%) Pb 10.15 Cu 1.47 As 36.43 Bi 1.76 Sb 25.18 <![CDATA[SiO2]]> 1.30 Ag 5.58 F 0.93

[0041] (2) The oxidized high-arsenic lead anode mud is roasted in a nitrogen atmosphere to remove arsenic, and the roasted high-arsenic lead anode mud is obtained. The roasting temperature for roasting and removing arsenic is 600°C, the nitrogen flow rate is 0.5L / min, and the roasting time is 0.5h. Table 2 shows the test results of the effect of natural oxidation days on the volatilization rate of arsenic, antimony, and bismuth. The appearance of the lead anode mud before and after roasting at different natural oxidation days is as follows Figure 1 and Figure 2 shown.

[0042] Table 2 Test results corresponding to different natural oxidation days

[0043]

[0044] From Table 1, Figure 1 , Figure 2 It can be seen that with the increase of the natural oxidation days of lead anode mud, the mass of lead anode mud after oxidation increases, the color of lead anode mud gradually turns gray, and there is agglomeration. After the natural oxidation days exceed 30 days, the mass increase trend of lead anode mud slows down. With the increase of the natural oxidation days of lead anode mud, the volatilization of arsenic, antimony and bismuth first increases and then decreases. When the natural oxidation days are 30 days, the lead anode mud still has a relatively obvious melting phenomenon after roasting, the roasting sand yield is 52.70%, and the volatilization rates of As, Sb and Bi are 84.30%, 25.60% and 39.81% respectively. When the natural oxidation days are extended to 60 days, the melting of roasting sand is improved, and the volatilization rates of As, Sb and Bi are reduced to 82.14%, 13.23% and 38.32% respectively. Considering the material properties of lead anode mud and the volatilization rates of arsenic, antimony and bismuth, the natural oxidation days of fresh lead anode mud are preferably around 60 days.

[0045] Example 2

[0046] Study on the effect of atmosphere on the volatility of arsenic, antimony and bismuth

[0047] Under the conditions of high arsenic lead anode mud mass of 20.00g, gas flow rate of 0.5L / min, and roasting time of 0.5h, volatilization roasting and arsenic removal tests were carried out in nitrogen and air atmospheres respectively. The test results are shown in Table 3. The appearance of the roasted sand after roasting is as follows: Figure 3 The chemical composition of high arsenic lead anode mud is as shown in Example 1.

[0048] Table 3 Results of arsenic removal by volatilization roasting under nitrogen and air atmosphere

[0049]

[0050] From Table 3 and Figure 3It can be seen that the anode mud melts when the temperature is between 500 and 600°C and roasted in air or nitrogen atmosphere. When roasted by volatilization in nitrogen atmosphere, the temperature is increased from 500°C to 600°C, and the volatilization rates of arsenic and antimony increase from 26.74% and 8.94% to 38.99% and 16.43% respectively, while the volatilization rate of bismuth is relatively low; at a roasting temperature of 600°C, the volatilization rates of arsenic and antimony in air atmosphere volatilization roasting are 29.31% and 11.55% respectively, which are 9.68% and 4.88% lower than those in nitrogen atmosphere volatilization roasting.

[0051] In summary, under optimized process conditions, the arsenic volatilization rate of high-arsenic lead anode mud is low when nitrogen or air atmosphere is used for volatilization roasting. The arsenic volatilization rate in nitrogen atmosphere is 38.99%, and the arsenic volatilization rate in air atmosphere is 29.31%. The lead anode mud material melts. This is because the high-arsenic lead anode mud is fresh lead anode mud with less natural oxidation, and contains a large amount of low-melting-point lead arsenate, which makes it difficult to volatilize and remove the arsenic.

[0052] Example 3

[0053] In this example, an air pre-oxidation-roasting arsenic removal test was investigated, and the effects of pre-oxidation temperature and time on the volatilization rates of arsenic, antimony and bismuth, and the effects of pre-oxidation air flow on the volatilization rates of arsenic, antimony and bismuth were investigated respectively.

[0054] 1. Investigate the effect of pre-oxidation temperature and time on the volatilization rate of arsenic, antimony and bismuth

[0055] In order to increase the melting point of fresh lead anode mud material, air is first used for pre-oxidation at low temperature for a period of time to oxidize the low-valent lead and elemental arsenic in the lead anode mud as much as possible, thereby creating favorable conditions for the efficient removal of arsenic.

[0056] Take 20.00g of high-arsenic lead anode mud, the chemical composition of which is as shown in Example 1, control the pre-oxidation air flow rate to 0.5L / min, and at a temperature of 200°C to 350°C, pre-oxidize for a period of time, and then investigate the effect of air pre-oxidation conditions on the volatilization rates of arsenic, antimony and bismuth under the conditions of a roasting temperature of 600°C, a roasting time of 0.5h and a roasting air flow rate of 0.5L / min. The test results are shown in Figure 4. The appearance of roasted sand after roasting and arsenic removal under different air pre-oxidation conditions is as follows: Figure 5 shown.

[0057] Table 4 Test results of air pre-oxidation conditions

[0058]

[0059] From Table 4 and Figure 4It can be seen that when the pre-oxidation time is the same, with the increase of the pre-oxidation temperature, the arsenic volatilization rate increases significantly, the antimony volatilization rate does not change significantly, and the bismuth volatilization rate shows an increasing trend. When the pre-oxidation temperature is 200℃ and the pre-oxidation time is 2h and 3h respectively, the anode mud still melts, and the As volatilization rate is also low, which is 35.71% and 33.07% respectively. When the pre-oxidation temperature is increased to 300℃ and the pre-oxidation time is 1h, 2h, and 3h respectively, the appearance of the anode mud after volatilization roasting and arsenic removal changes significantly, the melting degree of the anode mud is significantly improved, and the arsenic volatilization rate is greatly increased, which is increased to 80.68%, 77.97%, and 77.27% respectively. When the pre-oxidation temperature is increased to 350℃ and the pre-oxidation time is 2h, the melting degree of the anode mud after volatilization roasting and arsenic removal is aggravated again, and the arsenic volatilization rate is increased to 78.97%, which is not much of an increase. At the same pre-oxidation temperature, as the pre-oxidation time increases, the volatilization rate of arsenic decreases, while the volatilization rates of antimony and bismuth do not change significantly. Therefore, the pre-oxidation temperature should be controlled at around 300°C, and the pre-oxidation time should be around 1 hour.

[0060] 2. Investigate the effect of pre-oxidation air flow on the volatilization rate of arsenic, antimony and bismuth

[0061] Take 20.00g of high-arsenic lead anode mud, control a certain pre-oxidation air flow rate, at a pre-oxidation temperature of 300℃, after pre-oxidation for 1h, at a roasting temperature of 600℃, a roasting time of 0.5h, and a roasting air flow rate of 0.5L / min, the effect of pre-oxidation air flow rate on the volatilization rate of arsenic, antimony and bismuth is investigated. The test results are shown in Table 5. The appearance of roasted sand after roasting with different pre-oxidation air flow rates is as follows: Figure 5 shown.

[0062] Table 5 Pre-oxidation air flow condition test results

[0063]

[0064] From Table 5 and Figure 5 It can be seen that as the pre-oxidation air flow rate increases from 0.15L / min to 0.5L / min, the volatilization rate of arsenic increases slightly. When it continues to increase to 1.0L / min, the volatilization rate no longer increases. The volatilization rates of antimony and bismuth are not significantly affected by the pre-oxidation air flow rate. Therefore, the pre-oxidation air flow rate is preferably around 0.5L / min.

[0065] Example 4

[0066] This example conducts a kilogram-level expansion verification test

[0067] Under the optimized process conditions of pre-oxidation temperature of 300°C, pre-oxidation time of 1h, roasting temperature of 600°C, and roasting time of 0.5h, the effect of high-arsenic lead anode mud dosage on the volatilization rate of arsenic, antimony, and bismuth was investigated. The chemical composition of high-arsenic lead anode mud is as shown in Example 1. The sample of high-arsenic lead anode mud before roasting is as shown in Example 1. Figure 6 The test results are shown in Table 6. The appearance of the baked sand after roasting with different lead anode mud dosages is as follows: Figure 7 shown.

[0068] Table 6 Results of the air pre-oxidation-roasting arsenic removal expansion test

[0069]

[0070] From Table 6 and Figure 7 It can be seen that with the increase in the amount of high-arsenic lead anode mud, the thickness of the material layer increases. When it increases to 500.00g, the lead anode mud can still be completely oxidized, the volatilization rate of arsenic can reach 77.20%, and the volatilization rate of antimony can be controlled at about 10%. The results of the expanded verification test of the protective atmosphere resistance furnace are basically consistent with the results of the small-scale test of the tubular furnace.

[0071] When the dosage is expanded to 1000.00 g, there is a layer of melted anode mud (such as Figure 8 This is because the amount of lead anode mud increased and the thickness of the material layer increased, so that the lower layer of raw materials could not fully contact with the air to undergo oxidation reaction, resulting in a decrease in the volatilization rate of arsenic.

[0072] Example 5

[0073] In this embodiment, a volatilization roasting method for removing arsenic under a weakly oxidizing atmosphere of a nitrogen-oxygen mixed gas is adopted to investigate the effects of roasting temperature and different nitrogen-oxygen mixed atmospheres on the volatilization rates of arsenic, antimony, and bismuth, including the effects of roasting temperature on the volatilization rates of arsenic, antimony, and bismuth and the effects of different nitrogen-oxygen mixed atmospheres on the volatilization rates of arsenic, antimony, and bismuth.

[0074] 1. Effect of calcination temperature on the volatilization rate of arsenic, antimony and bismuth

[0075] Under the conditions that the mass of high-arsenic lead anode mud is 20.00 g, the flow rate of nitrogen-oxygen mixed gas (95% nitrogen + 5% oxygen) is 0.5 L / min, and the roasting time is 2.0 h, the effect of roasting temperature on the volatilization rate of arsenic, antimony and bismuth is investigated, and the test results are shown in Table 7. The chemical composition of high-arsenic lead anode mud is as shown in Example 1.

[0076] Table 7 Test results of calcination temperature conditions under (95% nitrogen + 5% oxygen) atmosphere

[0077]

[0078] It can be seen from Table 7 that when volatilizing and roasting in a nitrogen-oxygen mixed gas atmosphere (95% nitrogen + 5% oxygen), the temperature has a great influence on the volatilization rates of As, Sb, and Bi. When the temperature is between 400 and 500°C, as the temperature increases, the volatilization rate of arsenic increases rapidly, and the volatilization rates of antimony and bismuth increase to a certain extent. When the temperature is between 500 and 600°C, as the temperature increases, the volatilization rate of arsenic increases rapidly, and the volatilization rates of antimony and bismuth do not change much. When the temperature is > 600°C, the temperature continues to rise, the volatilization rate of arsenic increases, and the volatilization of antimony and bismuth also intensifies; due to the low melting point of lead anode mud, the material is prone to sintering. Therefore, it is difficult to achieve the decomposition of residual arsenic compounds and increase the volatilization rate of arsenic by simply increasing the temperature.

[0079] Therefore, in order to remove arsenic as much as possible and limit the volatilization of antimony and bismuth into the smoke as much as possible to achieve effective separation of arsenic from antimony and bismuth, the temperature should be controlled at no more than 650°C.

[0080] 2. Effects of different nitrogen and oxygen mixed atmospheres on the volatility of arsenic, antimony and bismuth

[0081] Under the conditions of high arsenic lead anode mud mass of 20.00g, roasting temperature of 650℃, gas flow rate of 0.5L / min and roasting time of 2.0h, the effect of oxygen concentration of nitrogen-oxygen mixed gas on the volatilization rate of arsenic, antimony and bismuth was investigated. The test results are shown in Table 8.

[0082] Table 8 Oxygen concentration condition test results

[0083]

[0084] It can be seen from Table 8 that with the increase of oxygen volume concentration in nitrogen-oxygen mixed gas, the roasting sand yield increases, and the volatilization rates of arsenic, antimony and bismuth decrease. When the oxygen volume concentration increases from 5% to 10%, the arsenic volatilization rate decreases significantly, from 85.43% to 61.18%, and the volatilization rates of antimony and bismuth also decrease, from 8.14% and 18.87% to 4.73% and 15.12% respectively; when the oxygen volume concentration continues to increase, the volatilization rates of arsenic, antimony and bismuth all decrease, but the decrease is not large. Therefore, increasing the oxygen volume concentration in nitrogen-oxygen mixed gas will inhibit the volatilization of arsenic, antimony and bismuth.

[0085] Example 6

[0086] Volatilization roasting in nitrogen or nitrogen-oxygen mixed gas atmosphere has an ideal removal effect on elemental As and As(III), but cannot remove As(V) phase in high-arsenic lead anode mud. In order to reduce As(V) to volatile As2O3, reduction roasting is carried out in N2-CO atmosphere to remove arsenic and inhibit excessive reduction of arsenic, so as to further improve the removal rate of arsenic in high-arsenic lead anode mud.

[0087] The raw material for the reduction roasting arsenic removal test is lead anode mud after nitrogen roasting arsenic removal. Its main chemical components are shown in Table 9, and the results of X-ray diffraction analysis show that the main phases in the lead anode mud after roasting arsenic removal under nitrogen atmosphere are Ag, As2O3, CuSb2O6, Pb3Bi(AsO4)3, SiO2, AsSbO4, Ag3Sb, PbF2, BiAsO4, and Sb2O4.

[0088] Table 9 Main chemical components of lead anode mud after roasting in nitrogen atmosphere

[0089] element As Sb Bi content(%) 15.29 35.38 1.81

[0090] 1. Investigate the effect of reduction roasting time on the volatilization rate of arsenic, antimony and bismuth

[0091] Under the conditions of 15.00 g mass of high-arsenic lead anode mud after roasting, 0.5 L / min N2-CO gas flow rate, 5% CO volume concentration, and 600°C roasting temperature, the effect of reduction roasting time on the volatilization rate of arsenic, antimony, and bismuth was investigated. The test results are shown in Table 10.

[0092] Table 10 Reduction roasting time condition test results

[0093]

[0094] It can be seen from Table 10 that when the reduction roasting time is extended from 0.5h to 3.0h, the arsenic content in the dearsenicized anode mud gradually decreases, the arsenic volatilization rate increases from 18.12% to 40.67%, and the volatilization rates of antimony and bismuth do not change significantly. Therefore, the optimal roasting time is 3.0h.

[0095] 2. Investigate the effect of reduction roasting temperature on the volatilization rate of arsenic, antimony and bismuth

[0096] Since the raw material used in the reduction roasting time condition test is the dearsenicized anode mud obtained by mixing in the nitrogen roasting dearsenicization condition test, which contains a small amount of low-valent arsenic phase, the arsenic volatilization rate is relatively high during reduction roasting.

[0097] Under the conditions that the mass of high-arsenic lead anode mud after roasting is 15.00g, the N2-CO gas flow rate is 0.5L / min, the CO volume concentration is 5%, and the roasting time is 3.0h, the effect of reduction roasting temperature on the volatilization rate of arsenic, antimony and bismuth is investigated. The experimental results are shown in Table 11.

[0098] Table 11 Reduction roasting temperature test results

[0099]

[0100] Note: The volume concentration of DTSHYZ-5CO is 0%.

[0101] It can be seen from Table 11 that with the increase of reduction roasting temperature, the volatilization rates of As, Sb and Bi all increase. When the reduction roasting temperature increases from 600℃ to 650℃, the volatilization rate of As increases from 10.31% to 44.15%, the volatilization rate of Sb does not increase significantly, and the volatilization rate of Bi increases from 31.46% to 53.85%. When the reduction temperature is further increased to 700℃, the volatilization rates of As, Sb and Bi increase to 92.16%, 18.18% and 97.75% respectively. When the temperature is 700℃ and the CO volume concentration is 0, the volatilization rate of As drops to 46.62%, and Sb and Bi are almost non-volatile.

[0102] In summary, the reduction roasting process can further reduce the arsenic content in lead anode mud and improve the arsenic removal rate. The cumulative arsenic removal rate can reach more than 96%.

[0103] Furthermore, this application proves that for fresh high-arsenic lead anode mud, the "natural oxidation-roasting dearsenification" or "air low-temperature pre-oxidation-roasting dearsenification" process can achieve effective separation of arsenic from antimony and bismuth. The economic benefits of the two processes are analyzed below.

[0104] 1. “Natural oxidation-roasting arsenic removal” process

[0105] Natural oxidation process conditions: natural oxidation days are not less than 60 days; roasting arsenic removal process conditions: roasting temperature is 600℃, nitrogen flow rate is 0.5L / min, and roasting time is 0.5h. Under the above conditions, the roasting sand yield is 59%, the roasting sand contains 11.03% As, 37.03% Sb, the As removal rate is 82.14%, and the Sb volatilization rate is 13.23%.

[0106] (1) Roasting cost of “natural oxidation-roasting dearsenicization” process

[0107] The roasting temperature is 600℃ and the roasting time is 0.5h. After consulting relevant manufacturers, the roasting temperature is 600℃ and the closed electric furnace can process 1t of material with an operating power of about 500kW; the nitrogen consumption is 400-500Nm 3 / t 铅阳极泥 (Take the average of 450Nm 3 / t 铅阳极泥 ), the price of nitrogen fluctuates, and the average price from January to October 2024 is 0.3 yuan / Nm 3 ; The average electricity price from January to October 2024 is 0.48 yuan / kW.h.

[0108] Roasting cost = 0.5 × 500 × 0.48 + 450 × 0.3 = 255 yuan / t 铅阳极泥

[0109] (2) Save reduction smelting costs

[0110] The "natural oxidation-roasting arsenic removal" process is used for pre-arsenic removal, and the roasted sand yield is 59%. Only this part of the roasted sand enters the reduction smelting furnace for further treatment; but if this process is not used for pre-arsenic removal, all the anode mud must enter the reduction smelting furnace for treatment. Smelting temperature: 900℃, smelting time: 12 hours / furnace, charging amount: 8-10t lead anode mud / furnace (9t on average), effective smelting volume excluding furnace bricks: Φ2050×3640, anthracite dosage: 1-2% of total feeding (1.5% on average), soda ash dosage: 10% of total feeding, precious lead yield: 35-55% (varies according to the different components of lead anode mud), precious lead silver content: 10-15% (varies according to the different components of lead anode mud), silver reduction slag yield: 15-25%, silver content 800-1200g / t, arsenic antimony smoke yield 35-40%, silver content 300-600g / t, natural gas dosage 130-160Nm 3 / t 铅阳极泥 (Take the average 145Nm 3 / t 铅阳极泥 ), about 95% of pipeline oxygen, oxygen volume is about 400-500Nm 3 / t 铅阳极泥 (Take the average of 450Nm 3 / t 铅阳极泥 ), natural gas prices fluctuate, averaging 2.85 yuan / Nm from January to October 2024 3 ; The average price of anthracite from January to October 2024 is 1,700 yuan / t; the average price of oxygen from January to October 2024 is 0.60 yuan / Nm 3 (excluding tax); the average price of electricity from January to October 2024 is 0.48 yuan / kW.h (excluding tax); the price of soda ash is about 1,800 yuan / t. The operating power of the converter motor is 20kW.

[0111] Saving of smelting cost = 0.015 × 1700 × (1-0.59) + 0.1 × 1800 × (1-0.59) + 145 × 2.85 × (1-0.59) + 450 × 0.6 × (1-0.59) + 20 × 24 × 0.48 × (1-0.59) / 18 = 369.64 yuan / t 铅阳极泥

[0112] Total economic benefits = (369.64-255) × 2500 = 286,600 yuan / year

[0113] 2. “Air pre-oxidation-roasting to remove arsenic” process

[0114] Air pre-oxidation process conditions: pre-oxidation air flow rate is 0.5L / min, pre-oxidation temperature is 300℃, and pre-oxidation time is 1h; roasting arsenic removal process conditions: roasting temperature is 600℃, roasting time is 0.5h, and roasting air flow rate is 0.5L / min. Under the above conditions, the roasted sand yield is 62.55%, the roasted sand contains 11.25% As, 35.83% Sb, the As removal rate is 80.68%, and the Sb volatilization rate is 10.99%.

[0115] (1) Roasting cost of “air pre-oxidation-roasting to remove arsenic” process

[0116] The roasting temperature is 600℃ and the roasting time is 0.5 hours. After consulting relevant manufacturers, the roasting temperature is 600℃ and the closed electric furnace can process 1t of material with an operating power of about 500kW; the air consumption is 400-500Nm 3 / t 铅阳极泥 (Take the average of 450Nm 3 / t 铅阳极泥 ), the air injection cost is about 0.1 yuan / Nm 3 ; The average electricity price from January to October 2024 is 0.48 yuan / kwh.

[0117] Roasting cost = 1 × 500 × 0.5 × 0.48 + 450 × 0.1 + 0.5 × 500 × 0.48 + 450 × 0.1 = 330 yuan / t 铅阳极泥

[0118] (2) Save reduction smelting costs

[0119] The "air pre-oxidation-roasting arsenic removal" process is used for pre-arsenic removal, and the roasted sand yield is 62.55%. Only this part of the roasted sand enters the reduction smelting furnace for further treatment; but if this process is not used for pre-arsenic removal, all the anode mud must enter the reduction smelting furnace for treatment. Smelting temperature: 900℃, smelting time: 12 hours / furnace, charging amount: 8-10t lead anode mud / furnace (9t on average), effective smelting volume excluding furnace bricks: Φ2050×3640, anthracite dosage: 1-2% of total feeding (1.5% on average), soda ash dosage: 10% of total feeding, precious lead yield: 35-55% (varies according to the different components of lead anode mud), precious lead silver content: 10-15% (varies according to the different components of lead anode mud), silver reduction slag yield: 15-25%, silver content 800-1200g / t, arsenic antimony smoke yield 35-40%, silver content 300-600g / t, natural gas dosage 130-160Nm 3 / t 铅阳极泥 (Take the average 145Nm 3 / t 铅阳极泥 ), about 95% of pipeline oxygen, oxygen volume is about 400-500Nm 3 / t铅阳极泥 (Take the average of 450Nm 3 / t 铅阳极泥 ), natural gas prices fluctuate, averaging 2.85 yuan / Nm from January to October 2024 3 ; The average price of anthracite from January to October 2024 is 1,700 yuan / t; the average price of oxygen from January to October 2024 is 0.60 yuan / Nm 3 (excluding tax); the average price of electricity from January to October 2024 is 0.48 yuan / kW.h (excluding tax); the price of soda ash is about 1,800 yuan / t. The operating power of the converter motor is 20kW.

[0120] Saving of smelting cost = 0.015 × 1700 × (1-0.6255) + 0.1 × 1800 × (1-0.6255) + 145 × 2.85 × (1-0.6255) + 450 × 0.6 × (1-0.6255) + 20 × 24 × 0.48 × (1-0.6255) / 18 = 337.63 yuan / t 铅阳极泥

[0121] Total economic benefits = (337.63-330) × 2500 = 19,100 yuan / year

[0122] In summary, the cost of pre-desarsenicization using the above two processes is lower than that of the existing direct reduction smelting treatment of lead anode mud, especially the "natural oxidation-roasting dearsenicization" process has lower costs; in addition, considering pre-desarsenicization followed by reduction smelting can reduce the output of silver reduction slag and arsenic-antimony smoke in the reduction smelting process, avoid the introduction of most of the arsenic causing the entrainment of precious metals such as gold and silver in the silver reduction slag and arsenic-antimony smoke, which is beneficial to improving the recovery rate and direct recovery rate of precious metals such as gold and silver in the precious lead smelting process, and is also beneficial to reducing environmental pollution and occupational health and safety risks.

[0123] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for removing arsenic from high-arsenic lead anode mud, characterized in that: The following steps are involved: (1) placing the high-arsenic lead anode mud in air at room temperature for natural oxidation for not less than 30 days or pre-oxidizing with air to obtain oxidized high-arsenic lead anode mud; The specific operation of pre-oxidation with air is as follows: air flow rate is 0.15-1L / min, pre-oxidation temperature is 300-350°C, and pre-oxidation time is 1-3h; (2) roasting the oxidized high-arsenic lead anode mud in a nitrogen atmosphere or in a nitrogen-oxygen mixed gas atmosphere to remove arsenic, thereby obtaining roasted high-arsenic lead anode mud; The nitrogen-oxygen mixed gas atmosphere is a mixed gas of nitrogen and oxygen, and the volume ratio of nitrogen in the mixed gas is 95%.

2. The method for removing arsenic from high-arsenic lead anode mud according to claim 1, characterized in that: The method also includes the step of reducing and roasting the roasted high-arsenic lead anode mud in a N2-CO atmosphere to remove arsenic, and the arsenic-removed lead anode mud is obtained after the reduction roasting and arsenic removal; The specific operation of reducing and roasting to remove arsenic in N2-CO atmosphere is as follows: the volume ratio of CO in the N2-CO mixed gas is 5%, the flow rate of the N2-CO mixed gas is 0.5L / min, the roasting temperature is 650-700°C, and the roasting time is 2-3h.

3. The method for removing arsenic from high-arsenic lead anode mud according to claim 2, characterized in that: The specific operation of reducing and roasting to remove arsenic in N2-CO atmosphere is as follows: the volume concentration of CO in the N2-CO mixed gas is 5%, the flow rate of the N2-CO mixed gas is 0.5L / min, the roasting temperature is 700°C, and the roasting time is 3h.

4. The method for removing arsenic from high-arsenic lead anode mud according to claim 1 or 2, characterized in that: The natural oxidation time is not less than 60 days.

5. The method for removing arsenic from high-arsenic lead anode mud according to claim 1 or 2, characterized in that: The specific operation of pre-oxidation using air is: pre-oxidation air flow rate is 0.5L / min, pre-oxidation temperature is 300°C, and pre-oxidation time is 1h.

6. The method for removing arsenic from high-arsenic lead anode mud according to claim 1 or 2, characterized in that: The specific operation of calcining and removing arsenic in a nitrogen atmosphere is: the calcining temperature is 450-600° C., the nitrogen flow rate is 0.5 L / min, and the calcining time is 0.5-3 h.

7. The method for removing arsenic from high-arsenic lead anode mud according to claim 6, characterized in that: The specific operation of calcining and removing arsenic in a nitrogen atmosphere is: calcining temperature is 600° C., nitrogen flow rate is 0.5 L / min, and calcining time is 0.5 h.

8. The method for removing arsenic from high-arsenic lead anode mud according to claim 1, characterized in that: The high-arsenic lead anode mud has an arsenic mass fraction greater than or equal to 30wt%, and an antimony mass fraction greater than or equal to 25wt%.

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