Method for removing arsenic and recovering tin from arsenic-containing tin residue

Abstract

The present application belongs to the technical field of non-ferrous metallurgy, and particularly relates to a method for removing arsenic and recovering tin from arsenic-containing tin residue. The method comprises the following steps: mixing the arsenic-containing tin residue and a reducing agent, and then performing reduction roasting under vacuum conditions to obtain volatilization and residue, wherein the volatilization contains arsenic trioxide, and the residue is a recovered tin product; the reducing agent is anthracite, and the mass ratio of the reducing agent to the arsenic-containing tin residue is 1:8-12. In the present application, anthracite is used as the reducing agent to perform reduction roasting on the arsenic-containing tin residue under vacuum conditions, and the arsenic in the arsenic-containing tin residue is reduced to arsenic trioxide by changing the existing form of arsenic, which is more easily volatilized into the gas phase under vacuum conditions, thereby achieving the removal of arsenic and the enrichment and recovery of tin. The method is simple, low in cost, high in reaction efficiency, high in arsenic removal rate, and high in tin recovery rate, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal metallurgy technology, specifically relating to a method for removing arsenic from arsenic-containing tin slag and recovering tin. Background Technology

[0002] Tin, along with tungsten, antimony, and rare earth elements, is known as one of the world's four major strategic metal resources. As one of the most widely used metals, tin is primarily applied in aerospace, electronics, conductors, the electronics industry, transportation, and construction, among other fields. Due to the depletion of available resources and the ever-increasing demand for tin, recovering tin from tin-containing secondary resources is crucial for alleviating resource shortages. During the hydrometallurgical extraction of tin from tin-containing secondary resources, over 90% of the arsenic is leached out along with the tin, resulting in arsenic-containing tin slag typically containing over 7% arsenic. This slag also contains other metals such as antimony, iron, and zinc. Therefore, arsenic-containing tin slag is an important non-ferrous metal resource, and developing clean and efficient technologies for its high-value and reduced-volume treatment is imperative.

[0003] Currently, the main technologies for treating arsenic-containing materials are divided into hydrometallurgical processes and pyrometallurgical processes. Depending on the leaching agent, hydrometallurgical processes are further divided into acid leaching, alkaline leaching, and neutralization leaching. Arsenic-containing materials are mostly leached with acidic solutions. The arsenic-containing residue after leaching is stored as arsenate precipitates such as ferric arsenate and calcium arsenate. The resulting arsenic-containing wastewater and arsenate slag still pose significant potential environmental hazards and require further treatment. Traditional pyrometallurgical arsenic removal processes are the earliest applied treatment methods, including direct roasting, oxidative roasting, and sulfide roasting. Through roasting, arsenic and its compounds are selectively separated in the form of arsenic trioxide, elemental arsenic, and arsenic sulfide. The arsenic-free material is then further smelted to recover other valuable metals. Pyrometallurgical treatment of arsenic-containing materials has the advantage of strong raw material applicability, but the arsenic removal rate is generally low, only about 70%. ～ Around 80%. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for removing arsenic from arsenic-containing tin slag and recovering tin. The method for removing arsenic from arsenic-containing tin slag and recovering tin provided by this invention has a high arsenic removal rate and a high tin recovery rate.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for removing arsenic and recovering tin from arsenic-containing tin slag, comprising the following steps:

[0007] Arsenic-containing tin slag and reducing agent are mixed and then reduced and roasted under vacuum conditions to obtain volatiles and residues, respectively. The volatiles contain arsenic trioxide and the residues are recycled tin products.

[0008] The reducing agent is anthracite, and the mass ratio of the reducing agent to arsenic-containing tin slag is 1:8 to 12.

[0009] Preferably, the reduction calcination temperature is 700–850°C, and the holding time is not less than 3 hours.

[0010] Preferably, the reduction calcination temperature is 750–800°C, and the holding time is 3–5 hours.

[0011] Preferably, the system pressure under the vacuum condition is 1 to 100 Pa.

[0012] Preferably, the mass ratio of the reducing agent to the arsenic-containing tin slag is 1:10.

[0013] Preferably, the fixed carbon content in the anthracite is 55-85 wt%.

[0014] Preferably, the anthracite has a moisture content of 1-3 wt%, an ash content of 25-30 wt%, and a volatile matter content of 6-10 wt%.

[0015] Preferably, the tin content in the arsenic-containing tin slag is 10-45% by mass.

[0016] Preferably, the mass fraction of arsenic in the arsenic-containing tin slag is 2-12%.

[0017] Preferably, the arsenic-containing tin slag further includes antimony, iron, and zinc, wherein the mass fraction of antimony in the arsenic-containing tin slag is 0.1-8%, the mass fraction of iron is 0.5-7%, and the mass fraction of zinc is 0.1-10%.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention provides a method for removing arsenic and recovering tin from arsenic-containing tin slag, comprising the following steps: mixing arsenic-containing tin slag with a reducing agent and then performing reduction roasting under vacuum conditions to obtain volatiles and residues, wherein the volatiles contain arsenic trioxide and the residues are recovered tin products; the reducing agent is anthracite, and the mass ratio of the reducing agent to the arsenic-containing tin slag is 1:8-12. This invention uses anthracite as a reducing agent to perform reduction roasting on arsenic-containing tin slag under vacuum conditions, reducing the arsenate in the arsenic-containing tin slag to arsenic trioxide. Utilizing the difference in properties between arsenic oxide (due to the change in the state of arsenic) and tin under vacuum conditions, and based on the fact that the saturated vapor pressure of arsenic trioxide is much greater than that of tin dioxide and tin, it is more easily volatilized into the gas phase under vacuum conditions, thereby reducing the arsenic content in the arsenic-containing tin slag while simultaneously enriching tin. The specific ratio of reducing agent to arsenic-containing tin slag in this invention will not lead to an excessively high reducing atmosphere, which would cause arsenic compounds to be reduced to elemental arsenic and combine with metals to form intermetallic compounds, thereby reducing the arsenic removal rate. The method for removing arsenic and recovering tin from arsenic-containing tin slag in this invention has a high arsenic removal rate and a high tin recovery rate.

[0020] Furthermore, the method for removing arsenic and recovering tin from arsenic-containing tin slag of the present invention has the advantages of simple operation and low cost. Moreover, under vacuum conditions, it can achieve efficient removal and recovery of arsenic in a short time. The chemical reaction requires a lower temperature and has high reaction efficiency, showing good prospects for industrial application. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of the method for removing arsenic and recovering tin from arsenic-containing tin slag according to the present invention;

[0023] Figure 2 The image shows the EMPA diagram of the calcined product obtained in Example 1.

[0024] Figure 3 The image shows the EPMA diagram of the calcined product obtained in Comparative Example 1. Detailed Implementation

[0025] This invention provides a method for removing arsenic and recovering tin from arsenic-containing tin slag, comprising the following steps:

[0026] Arsenic-containing tin slag and reducing agent are mixed and then reduced and roasted under vacuum conditions to obtain volatiles and residues, respectively. The volatiles contain arsenic trioxide and the residues are recycled tin products.

[0027] The reducing agent is anthracite, and the mass ratio of the reducing agent to arsenic-containing tin slag is 1:8 to 12.

[0028] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0029] This invention involves mixing arsenic-containing tin slag with a reducing agent and then subjecting it to reduction roasting under vacuum conditions.

[0030] In this invention, the mass fraction of tin in the arsenic-containing tin slag is preferably 10-45%, more preferably 17.70-29.21%.

[0031] In this invention, the mass fraction of arsenic in the arsenic-containing tin slag is preferably 2-12%, more preferably 7.39-8.33%.

[0032] In this invention, the arsenic-containing tin slag preferably also includes one or more of antimony, iron, zinc, calcium, and sodium, and the balance of elements such as C, N, or O that are not determined by full elemental analysis; the mass fraction of antimony in the arsenic-containing tin slag is preferably 0.1-8%, the mass fraction of iron is preferably 0.5-7%, the mass fraction of zinc is preferably 0.1-10%, the mass fraction of calcium is preferably 0.1-10%, and the mass fraction of sodium is preferably 0.1-12%. In a specific embodiment of the present invention, the arsenic-containing tin slag used is preferably an arsenic-containing tin slag comprising the following components: Sn (17.70 wt%), As (8.33 wt%), Sb (3.46 wt%), Fe (1.19 wt%), Zn (6.52 wt%), Ca (6.45 wt%), and Na (3.74 wt%); or an arsenic-containing tin slag comprising the following components: Sn (29.21 wt%), As (7.39 wt%), Sb (0.96 wt%), Fe (2.88 wt%), Zn (5.47 wt%), Ca (5.43 wt%), and Na (4.72 wt%).

[0033] In this invention, the anthracite preferably has a moisture content of 1-3 wt%, an ash content of 25-30 wt%, a volatile matter content of 6-10 wt%, and a fixed carbon content of 55-85 wt%. In a specific embodiment of this invention, the anthracite is preferably anthracite with a moisture content of 1.41 wt%, an ash content of 28.45 wt%, a volatile matter content of 7.89 wt%, and a fixed carbon content of 62.25 wt%.

[0034] In this invention, the mass ratio of the reducing agent to the arsenic-containing tin slag is preferably 1:10.

[0035] In this invention, the system pressure under the vacuum condition is preferably 1 to 100 Pa, more preferably 10 Pa.

[0036] In this invention, the reduction calcination temperature is preferably 700-850°C, more preferably 750-800°C, and the holding time is preferably not less than 3 hours, more preferably 3-5 hours, and even more preferably 4 hours.

[0037] In this invention, the reduction roasting is preferably carried out in a tube furnace, and the arsenic-containing tin slag and reducing agent are preferably placed in a corundum crucible. Preferably, the temperature inside the tube furnace is lowered to below 100°C, the crucible is removed, and the collected roasting product is the recovered tin product (arsenic-removed tin slag). The arsenic content in the arsenic-removed tin slag is preferably 0.35–0.7 wt%, more preferably 0.53–0.64 wt%, and even more preferably 0.57–0.58 wt%.

[0038] Figure 1 The flowchart of the method for removing arsenic and recovering tin from arsenic-containing tin slag of the present invention is shown. Arsenic-containing tin slag and anthracite are mixed and then vacuum roasted. The arsenic in the arsenic-containing tin slag is reduced to arsenic trioxide. Since the saturated vapor pressure of arsenic trioxide is much greater than that of tin dioxide and tin, it is easier to volatilize into the gas phase (volatiles) under vacuum conditions, while tin is enriched in the residue, thereby achieving the removal of arsenic and the enrichment and recovery of tin.

[0039] To further illustrate the present invention, the method for arsenic removal and tin recovery from arsenic-containing tin slag provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0040] In Examples 1-4 and Comparative Examples 1-10, the arsenic-containing tin slag used was arsenic-containing tin slag containing the following components: Sn (17.70 wt%), As (8.33 wt%), Sb (3.46 wt%), Fe (1.19 wt%), and Zn (6.52 wt%). 、 Ca (6.45wt%), Na (3.74wt%), and the balance C, N or O, and other elements not determined by full elemental analysis.

[0041] In Example 5, the arsenic-containing tin slag used was an arsenic-containing tin slag comprising the following components: Sn (29.21 wt%), As (7.39 wt%), Sb (0.96 wt%), Fe (2.88 wt%), Zn (5.47 wt%), Ca (5.43 wt%), Na (4.72 wt%), and the balance C, N or O, etc., which are elements not determined by full elemental analysis.

[0042] Example 1

[0043] A method for removing arsenic and recovering tin from arsenic-containing tin slag includes the following steps:

[0044] Take 10g of arsenic-containing tin slag and place it in a corundum crucible. Mix anthracite (reducing agent) and the arsenic-containing tin slag thoroughly at a mass ratio of 1:10, wherein the anthracite contains 62.25wt% fixed carbon. Place the crucible in a vacuum tube furnace and perform vacuum reduction roasting treatment at a temperature of 750℃ for 3 hours and a pressure of 10Pa. After roasting is completed, when the temperature inside the furnace drops below 100℃, remove the crucible and collect the residue.

[0045] The final product (calcined product) contained 31.41% Sn by mass and 0.53% As by mass. The direct recovery rate of Sn was 84.48%, and the removal rate of As was 96.97%.

[0046] The direct recovery rate of Sn = (mass of residue * tin content in residue) / (mass of arsenic-containing tin slag * tin content in arsenic-containing tin slag), and the removal rate of As = (mass of arsenic-containing tin slag * arsenic content in arsenic-containing tin slag - mass of residue * arsenic content in residue) / (mass of arsenic-containing tin slag * arsenic content in arsenic-containing tin slag)

[0047] Example 2

[0048] The difference from Example 1 is that the calcination time is 4 hours, while the other conditions are the same as in Example 1.

[0049] The final product contained 31.42% Sn and 0.64% As. The direct recovery rate of Sn was 86.29%, and the removal rate of As was 96.26%.

[0050] Example 3

[0051] The difference from Example 1 is that the calcination time is 5 hours, while the other conditions are the same as in Example 1.

[0052] The final product contained 30.67% Sn and 0.58% As, with a Sn recovery rate of 83.19% and an As removal rate of 96.66%.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that the anthracite and arsenic-containing tin slag are mixed in a mass ratio of 1:4, while the other conditions are the same as in Example 1.

[0055] The final product contained 26.09% Sn and 1.63% As, with a Sn recovery rate of 84.03% and an As removal rate of 88.84%.

[0056] It can be seen that the removal rate of As in Example 1 is significantly higher than that in Comparative Example 1, and the arsenic content of the calcined product in Example 1 is much lower than that in Comparative Example 1.

[0057] Figure 2This is an EMPA image of the calcined product obtained in Example 1. Figure 3 The image shows the EPMA diagram of the calcined product obtained in Comparative Example 1. Figure 2 and Figure 3 It can be seen that when the reducing atmosphere is too high, arsenic compounds will be reduced to elemental arsenic. Elemental arsenic is easy to combine with other metals to form intermetallic compounds, which leads to a decrease in the arsenic removal rate.

[0058] Comparative Example 2

[0059] The difference from Example 1 is that the anthracite and arsenic-containing tin slag are mixed in a mass ratio of 1:7, while the other conditions are the same as in Example 1.

[0060] The final product contained 29.83% Sn and 1.22% As, with a Sn recovery rate of 87.31% and an As removal rate of 92.41%.

[0061] Comparative Example 3

[0062] The difference from Example 1 is that the anthracite and arsenic-containing tin slag are mixed in a mass ratio of 1:20, while the other conditions are the same as in Example 1.

[0063] The final product contained 31.85% Sn and 2.23% As. The direct recovery rate of Sn was 96.47%, and the removal rate of As was 85.64%.

[0064] Comparative Example 4

[0065] The difference from Example 1 is that the calcination time is 1 hour, while the other conditions are the same as in Example 1.

[0066] The final product contained 30.55% Sn and 1.61% As, with a Sn recovery rate of 93.91% and an As removal rate of 89.48%.

[0067] Comparative Example 5

[0068] The difference from Example 1 is that the calcination time is 2 hours, while the other conditions are the same as in Example 1.

[0069] The final product contained 30.09% Sn and 1.00% As, with a Sn recovery rate of 85.35% and an As removal rate of 93.97%.

[0070] Comparative Example 6

[0071] The difference from Example 1 is that the anthracite and arsenic-containing tin slag are mixed in a mass ratio of 1:5, the roasting temperature is 650℃, and the other conditions are the same as in Example 1.

[0072] The final product contained 24.14% Sn and 2.46% As, with a Sn recovery rate of 92.76% and an As removal rate of 79.91%.

[0073] Comparative Example 7

[0074] The difference from Example 1 is that the anthracite and arsenic-containing tin slag are mixed in a mass ratio of 1:5, the roasting temperature is 700℃, and the other conditions are the same as in Example 1.

[0075] The final product contained 26.16% Sn and 1.90% As, with a Sn recovery rate of 92.83% and an As removal rate of 85.67%.

[0076] Comparative Example 8

[0077] The difference from Example 1 is that the anthracite and arsenic-containing tin slag are mixed in a mass ratio of 1:5, the roasting temperature is 750℃, and the other conditions are the same as in Example 1.

[0078] The final product contained 26.75% Sn and 1.34% As, with a Sn recovery rate of 82.23% and an As removal rate of 91.24%.

[0079] Comparative Example 9

[0080] The difference from Example 1 is that the anthracite and arsenic-containing tin slag are mixed in a mass ratio of 1:5, the roasting temperature is 800℃, and the other conditions are the same as in Example 1.

[0081] The final product contained 26.98% Sn and 1.18% As, with a Sn recovery rate of 71.74% and an As removal rate of 93.42%.

[0082] Comparative Example 10

[0083] The difference from Example 1 is that the anthracite and arsenic-containing tin slag are mixed in a mass ratio of 1:5, the roasting temperature is 850℃, and the other conditions are the same as in Example 1.

[0084] The final product contained 22.32% Sn and 1.30% As, with a Sn recovery rate of 53.98% and an As removal rate of 93.32%.

[0085] Example 4

[0086] A method for removing arsenic and recovering tin from arsenic-containing tin slag includes the following steps:

[0087] Take 20g of arsenic-containing tin slag and place it in a corundum crucible. Mix anthracite and arsenic-containing tin slag thoroughly at a mass ratio of 1:10, wherein the anthracite contains 62.25wt% fixed carbon. Place the crucible in a vacuum tube furnace and perform vacuum reduction roasting at a temperature of 750℃ for 5 hours and a pressure of 10Pa. After roasting, when the temperature inside the furnace drops below 100℃, remove the crucible and collect the residue.

[0088] The final product contained 31.42% Sn and 0.64% As. The direct recovery rate of Sn was 86.29%, and the removal rate of As was 96.26%.

[0089] Example 5

[0090] A method for removing arsenic and recovering tin from arsenic-containing tin slag includes the following steps:

[0091] Take 10g of arsenic-containing tin slag (the composition of the arsenic-containing tin slag is: Sn (29.21wt%), As (7.39wt%), Sb (0.96wt%), Fe (2.88wt%), Zn (5.47wt%), Ca (5.43wt%), and Na (4.72wt%) and place it in a corundum crucible. Mix anthracite and the arsenic-containing tin slag thoroughly at a mass ratio of 1:10, wherein the anthracite contains 62.25wt% fixed carbon. Place the crucible in a vacuum tube furnace and perform vacuum reduction roasting treatment at a roasting temperature of 800℃ for 3 hours and a pressure of 10Pa. After roasting is completed, when the temperature inside the furnace drops below 100℃, remove the crucible and collect the residue.

[0092] The final product contained 46.38% Sn and 0.57% As, with a Sn recovery rate of 82.09% and an As removal rate of 96.01%.

[0093] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on the present invention without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for removing arsenic and recovering tin from arsenic-containing tin slag, characterized in that, Includes the following steps: Arsenic-containing tin slag and reducing agent are mixed and then reduced and roasted under vacuum conditions to obtain volatiles and residues, respectively. The volatiles contain arsenic trioxide and the residues are recycled tin products. The reducing agent is anthracite, and the mass ratio of the reducing agent to arsenic-containing tin slag is 1:8~12; The reduction calcination temperature is 700~850℃, and the holding time is not less than 3 hours.

2. The method for removing arsenic and recovering tin from arsenic-containing tin slag according to claim 1, characterized in that, The reduction calcination temperature is 750~800℃, and the holding time is 3~5h.

3. The method for removing arsenic and recovering tin from arsenic-containing tin slag according to claim 1, characterized in that, The system pressure under the vacuum condition is 1~100 Pa.

4. The method for removing arsenic and recovering tin from arsenic-containing tin slag according to claim 1, characterized in that, The mass ratio of the reducing agent to the arsenic-containing tin slag is 1:

10.

5. The method for removing arsenic and recovering tin from arsenic-containing tin slag according to claim 1 or 4, characterized in that, The fixed carbon content in the anthracite is 55-85 wt%.

6. The method for removing arsenic and recovering tin from arsenic-containing tin slag according to claim 5, characterized in that, The anthracite has a moisture content of 1-3 wt%, an ash content of 25-30 wt%, and a volatile matter content of 6-10 wt%.

7. The method for removing arsenic and recovering tin from arsenic-containing tin slag according to claim 1, characterized in that, The tin mass fraction in the arsenic-containing tin slag is 10-45%.

8. The method for removing arsenic and recovering tin from arsenic-containing tin slag according to claim 7, characterized in that, The mass fraction of arsenic in the arsenic-containing tin slag is 2-12%.

9. The method for removing arsenic and recovering tin from arsenic-containing tin slag according to claim 7, characterized in that, The arsenic-containing tin slag also includes antimony, iron, and zinc. The mass fraction of antimony in the arsenic-containing tin slag is 0.1-8%, the mass fraction of iron is 0.5-7%, and the mass fraction of zinc is 0.1-10%.

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