A method for obtaining high-grade tin concentrates from silver-splitter residues

Abstract

The application discloses a method for obtaining high-grade tin concentrate from silver separation residue, and specifically comprises the following steps: uniformly mixing silver separation residue, an additive and carbon powder according to a proportion, preparing spherical material, and obtaining roasting residue through rotary kiln roasting; grinding the obtained roasting residue into powder, using a reducing agent solution to perform tin leaching on the powdered roasting residue, obtaining leaching liquid and leaching residue, and sending the leaching residue to other valuable element recovery; adding an oxidizing agent to the obtained leaching liquid, selectively precipitating tin in the solution, and obtaining tin precipitation residue and tin precipitation liquid. The high-grade tin concentrate can be obtained after the tin precipitation residue is dried and washed. The method directly obtains the tin concentrate from the silver separation residue, and has the advantages of high grade, few impurities, simple overall process operation, small reagent consumption in the tin precipitation process, low cost, short reaction time and no need of heating.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal smelting technology, specifically relating to a method for obtaining high-grade tin concentrate from silver slag. Background Technology

[0002] The anode mud produced by copper electrolysis needs to undergo a series of processes to recover valuable elements. The residue left after the silver separation process is called silver separation slag, which contains trace amounts of gold and silver, as well as valuable metals such as tin, lead, and antimony. Tin in silver separation slag is highly valuable, but it usually exists in the stable form of tin dioxide, which is stable at room temperature and difficult to extract directly, resulting in resource waste. Currently, the commonly used extraction method is to convert stable tin dioxide into a soluble form through a high-temperature reduction reaction, then obtain a tin-containing leachate through wet leaching, and finally obtain a product with a relatively high tin content through a tin precipitation process.

[0003] However, the tin immersion process often uses calcium-containing reagents such as calcium oxide, calcium hydroxide, and calcium chloride to precipitate tin in the solution. In order to ensure that as much tin as possible is precipitated in the leaching solution, the amount of reagent added is often significantly excessive relative to the tin content. This not only wastes reagents but also precipitates impurities along with the tin. At the same time, some calcium enters the product, ultimately leading to a decrease in the tin content, an increase in impurities, and a reduction in quality. Summary of the Invention:

[0004] To address the aforementioned problems, this invention provides a method for obtaining high-grade tin concentrate from silver-separating slag, thereby solving any of the above-mentioned and other potential problems in the prior art.

[0005] To achieve the above objectives, the technical solution of the present invention is: a method for obtaining high-grade tin concentrate from silver-separating slag, the method specifically comprising the following steps performed sequentially:

[0006] S1) Mix the silver slag, additives and carbon powder evenly in proportion, form it into spherical material, and then calcine it in a rotary kiln to obtain calcined slag.

[0007] S2) Grind the calcined residue obtained in S1) to obtain calcined residue powder. Add the powder to a reducing agent solution and leach to obtain leachate and leaching residue. The leaching residue is sent for recovery of other valuable elements.

[0008] S3) An oxidant is added to the leachate to selectively precipitate tin in the solution, resulting in tin precipitate solution and tin precipitate slag. After drying and washing, the tin precipitate slag can be used to obtain high-grade tin concentrate.

[0009] Furthermore, in S1), the mass ratio of silver slag, carbon powder, and additives is 1:(0.2-1):(0.02-0.4). After mixing, the three are spherical, with a diameter of 0.3-3 cm.

[0010] Furthermore, the additive in S1) is one or more of sodium sulfide, calcium sulfide and magnesium sulfide.

[0011] Furthermore, the spherical material obtained in S1) is fed into a rotary kiln for roasting at a temperature of 500–900°C for a time of 0.5–3.0 h.

[0012] Furthermore, the roasted slag powder obtained by grinding in S2) has a particle size of <375μm (40 mesh);

[0013] Furthermore, in the leaching reaction process of S2), the reaction temperature is 50-90℃ and the time is 1-5h, and the entire leaching process is kept stirred; after leaching, the mixture is filtered to obtain leachate and leaching residue, and the leaching residue is sent for the recovery of other valuable elements.

[0014] Furthermore, the reducing agent used in the reducing agent solution in S2) is one or a combination of sodium sulfite, sodium bisulfite, sodium thiosulfate, and sodium oxalate.

[0015] Furthermore, the oxidant in S3) is one or a combination of several of hydrogen peroxide, sodium persulfate, potassium persulfate, and sodium percarbonate;

[0016] Furthermore, the specific process parameters in S3) are as follows: the amount of hydrogen peroxide added is 0.1-1 mol / L, the amount of sodium persulfate, potassium persulfate, and sodium percarbonate added is 0.01-0.5 mol / L, and the reaction time is 5-15 min.

[0017] Furthermore, the direct recovery rate of tin contained in the silver slag in the method is over 90%, and the tin content of the obtained tin concentrate is over 60%.

[0018] Compared with the prior art, the beneficial effects and outstanding advantages of the process of this invention are as follows:

[0019] 1) Using a reducing agent for leaching results in a higher leaching rate compared to conventional alkaline / acid leaching methods;

[0020] 2) The tin immersion reaction process does not require heating, has a short reaction time, low equipment requirements, and low energy consumption;

[0021] 3) The tin immersion process has good selectivity. Compared with other methods, the As and Sb contents in the obtained product are less than 0.4% and 0.3% respectively, and the Sn content is more than 60%. According to the tin concentrate standard, it can reach grade 3.

[0022] 4) The process is short, the recovery effect is good, and tin is selectively extracted from the silver slag, with a direct tin recovery rate of over 90%. Attached Figure Description

[0023] Figure 1The image shows the XRD pattern of the tin concentrate product from the method for obtaining high-grade tin concentrate from silver slag according to the present invention. Detailed Implementation

[0024] The present invention will be further described in detail below through embodiments, but the scope of the present invention is not limited to these embodiments. The present invention provides a method for obtaining high-grade tin concentrate from silver-separating slag, specifically comprising the following steps performed sequentially:

[0025] S1) Mix the silver slag, additives and carbon powder evenly in proportion, form it into spherical material, and then calcine it in a rotary kiln to obtain calcined slag.

[0026] S2) Grind the calcined residue obtained in S1) to obtain calcined residue powder. Add the powder to a reducing agent solution, heat and leach to obtain leachate and leaching residue. The leaching residue is sent for recovery of other valuable elements.

[0027] S3) An oxidant is added to the leaching solution to selectively precipitate tin, resulting in tin precipitate solution and tin slag. The tin slag, after drying and washing, yields high-grade tin concentrate. Figure 1 As can be seen from the data, the main component of this tin concentrate is tin dioxide.

[0028] The mass ratio of silver slag, carbon powder, and additives in S1) is 1:(0.2-1):(0.02-0.4). After mixing, the three are spherical, with a diameter of 0.3-3 cm.

[0029] The spherical material obtained in S1) is fed into a rotary kiln for roasting at a temperature of 500–900°C for a time of 0.5–3.0 h.

[0030] The additive in S1) is one or more of sodium sulfide, calcium sulfide and magnesium sulfide.

[0031] The calcined slag powder obtained by grinding in S2) has a particle size of <375μm (40 mesh);

[0032] The leaching reaction process in S2) is carried out at a temperature of 50-90°C for 1-5 hours, with stirring maintained throughout the leaching process; after leaching, the mixture is filtered to obtain leachate and leaching residue.

[0033] The reducing agent used in the reducing agent solution in S2) is one or a combination of sodium sulfite, sodium bisulfite, sodium thiosulfate, and sodium oxalate.

[0034] The oxidant in S3) is one or a combination of hydrogen peroxide and sodium persulfate, potassium persulfate, and sodium percarbonate.

[0035] The specific process parameters in S3) are as follows: the amount of hydrogen peroxide added is 0.1-1 mol / L, the amount of sodium persulfate, potassium persulfate, and sodium percarbonate added is 0.01-0.5 mol / L, and the reaction time is 5-15 min.

[0036] The method described above achieves a direct recovery rate of over 90% for tin in the silver slag, and the resulting tin concentrate contains over 60% tin.

[0037] Example 1

[0038] 1000g of wet silver-separating slag, 300g of carbon powder, and 30g of calcium sulfide were mixed and formed into pellets with a particle size of approximately 1cm. These pellets were then fed into a rotary kiln and calcined at 800℃ for 1.5 hours to obtain calcined slag. The calcined slag was ground into powder with a particle size of less than 80 mesh. The obtained calcined slag powder was added to 4L of a 0.25mol / L sodium sulfite solution and stirred continuously. The temperature was then raised to 90℃, and the reaction was carried out for 3 hours. After filtration, leaching residue and leachate were obtained. 0.3L of hydrogen peroxide and 50g of sodium percarbonate were added to the leachate, and the reaction was carried out continuously for 5 minutes. After filtration, tin precipitate slag and tin precipitate solution were obtained. The tin precipitate slag was washed and dried to obtain tin concentrate. The elemental contents of the tin concentrate are shown in the table below. The direct tin recovery rate from silver-separating slag to tin precipitate slag was 91.1%.

[0039]

[0040] Table 1. Element content of the tin concentrate obtained in Example 1

[0041] Example 2

[0042] 700g of wet silver-separating slag, 40g of magnesium sulfide, and 200g of carbon powder were mixed and formed into pellets with a particle size of approximately 1cm. These pellets were then fed into a rotary kiln and roasted at 650℃ for 3 hours to obtain roasted slag. The roasted slag was ground into powder until most of the powder particles were below 200 mesh. While stirring, the obtained roasted slag powder was added to 3L of a 0.8mol / L sodium thiosulfate solution. The temperature was raised to 80℃, and after reacting for 2 hours, the mixture was filtered to obtain leaching residue and leachate. The leaching residue was sent for the recovery of other valuable elements. 45g of sodium persulfate and 0.15L of hydrogen peroxide were added to the leachate, and while stirring, the mixture was reacted for 10 minutes. After filtration, tin-precipitating slag and tin-precipitating solution were obtained. The tin-precipitating slag was washed and dried to obtain tin concentrate. The elemental contents of the tin concentrate are shown in the table below. The direct tin recovery rate from silver-separating slag to tin-precipitating slag was 90.2%.

[0043]

[0044] Table 2. Element content of tin concentrate obtained in Example 2

[0045] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for obtaining high-grade tin concentrate from silver-separating slag, characterized in that, The method specifically includes the following steps: S1) Silver slag, additives and carbon powder are mixed evenly in proportion, formed into spherical material, and then roasted in a rotary kiln to obtain roasted slag; The additives are one or a combination of sodium sulfide, calcium sulfide and magnesium sulfide. The specific steps are as follows: S1.1) Mix the silver slag, carbon powder, and additives in a mass ratio of 1:(0.2~1):(0.02~0.4). After mixing evenly, form the mixture into spheres to obtain spherical materials with a diameter of 0.3~3cm. S1.2) The spherical material obtained in S1.1) is fed into a rotary kiln for calcination at a temperature of 500–900℃ for a time of 0.5–3.0 h. S2) Grind the roasted residue obtained in S1) into powder, and use a reducing agent solution to leach the powdered roasted residue with tin to obtain a leachate and a leaching residue. The leaching residue is sent for recovery of other valuable elements. The reducing agent used in the reducing agent solution is one or a combination of sodium sulfite, sodium bisulfite, sodium thiosulfate, and sodium oxalate, with the concentration of each component ranging from 0.05 to 1 mol / L. The specific process parameters are as follows: S2.1) First, grind the roasted slag to obtain roasted slag powder with a particle size of <375μm; S2.2) The powder obtained in S2.1) is added to the reducing agent solution for leaching. The leaching temperature is 50-90℃ and the time is 1-5h, with stirring throughout the process. After leaching, the solution is filtered to obtain the leachate and the leaching residue. S3) Add an oxidant to the leachate obtained in S2) to selectively precipitate tin in the solution, and obtain tin slag and tin precipitate solution; after drying and washing, the tin slag can be used to obtain high-grade tin concentrate; the amount of hydrogen peroxide added is 0.1-1 mol / L, the amount of sodium persulfate, potassium persulfate and sodium percarbonate added is 0.01-0.5 mol / L, and the reaction time is 5-15 min.

2. The method according to claim 1, characterized in that, The silver-separating slag is anode mud silver-separating slag.

3. The method according to claim 1, characterized in that, The oxidant is hydrogen peroxide and one or more of sodium persulfate, potassium persulfate, and sodium percarbonate.

4. The method according to claim 1, characterized in that, The method described above results in a direct recovery rate of over 90% of the tin contained in the silver slag, and the tin concentrate obtained contains over 60% tin.

5. A tin concentrate, characterized in that, The tin concentrate is prepared by the method described in any one of claims 1-4.

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