Lead-tin separation method in tin soot wet recovery process

Abstract

The invention discloses a lead-tin separation method in a tin soot wet recovery process, which is used for lead-tin separation in slag charge after zinc and copper recovery of tin soot, and comprises the following steps: lead immersion: adding tin-lead mixed slag charge into prepared saturated chlorine-containing salt water to dissolve lead in the chlorine-containing salt water to obtain lead chloride salt water and tin sludge, thereby realizing lead-tin separation; the obtained tin mud is sold as a product; and lead removal: slaked lime is added into lead chloride saline water, lead slime and chlorine-containing saline water are obtained after the reaction is completed, the chlorine-containing saline water is returned to the lead dipping procedure, and the obtained lead slime can be sold as a byproduct. According to the method, tin and lead are effectively separated from the slag obtained after zinc and copper recovery of the tin soot is completed through a chemical method, the method is simple and easy to operate, the raw material cost is low, the grade of a tin sludge product is improved, meanwhile, a lead by-product is produced, and therefore the economic benefit of tin soot wet recovery is improved; and the whole process of lead-tin separation does not generate waste water, waste residues and waste gas, is environment-friendly and is worthy of popularization and application.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal hydrometallurgy, and in particular to a lead-tin separation method in a tin ash hydrometallurgy recovery process. Background Art

[0002] Tin ash is an industrial hazardous waste. The content of valuable metals in tin ash from different smelters varies. It can be used for the recovery and refining of valuable metals such as zinc, tin, lead and copper. In actual production applications, zinc and copper can be separated by leaching with sulfuric acid. If the tin and lead in the remaining slag are sold directly, they can only be sold at the price of high-priced metallic tin. Lead is not only not priced, but also regarded as an impurity that affects the price grade of tin. Although some manufacturers will consider lead recovery, it is not generally applicable to lead-tin separation in the wet recovery process of tin ash due to high energy consumption or complex process operation. Summary of the invention

[0003] In order to solve the problem that the lead content of tin mud is generated in the wet recovery and refining process of the above-mentioned existing tin fly ash, the lead content not only lowers the grade of the tin mud, but also the lead is not priced, reducing the company's output efficiency. The present invention provides a lead-tin separation method in the wet recovery process of tin fly ash, which uses a chemical method to achieve effective separation of tin and lead in the tin-lead mixed slag after the recovery of zinc and copper in tin fly ash. The method is simple and easy to operate and has low raw material cost. It not only improves the grade of the tin mud product, but also produces lead by-products, thereby improving the economic benefits of the wet recovery of tin fly ash.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A lead-tin separation method in a tin ash wet recovery process, characterized in that it comprises the following steps:

[0006] S1, leaching: adding tin ash to sulfuric acid solution, stirring to leach zinc and copper, and then filtering to obtain zinc- and copper-containing filtrate and filter residue, wherein the filter residue is a tin-lead mixed slag material, and the zinc- and copper-containing filtrate is sent to the zinc and copper production line for post-treatment of extracting copper and zinc;

[0007] S2, lead leaching: adding the tin-lead mixed slag obtained in step S1 to the prepared chlorine-containing Cl salt water, stirring and heating, and then filtering by pressure to obtain lead chloride salt water and filter residue, wherein the filter residue is tin mud, which can be directly sold as a product;

[0008] S3, lead removal: slowly add slaked lime Ca(OH)2 to the lead chloride brine obtained in step S2, stir and adjust to pH 8, stop adding, continue stirring for 30-60 min, then filter press to obtain the brine and filter residue after lead removal, the brine after lead removal is returned to the lead leaching process in step S2 for recycling, the filter residue is lead mud, which can be directly sold as a by-product.

[0009] Preferably, in step S1, the concentration of the sulfuric acid solution is set to 60 g / L, and leaching is carried out at 60° C. under normal pressure and stirring, the end point is stabilized between pH 1 and 2, and the leaching time is 4 hours.

[0010] Preferably, in the chlorine-containing Cl salt water in step S2, Cl≧180 g / L, and the solid-liquid ratio of the tin-lead mixed slag material to the chlorine-containing Cl salt water is set to 1:8-1:10. The chlorine-containing Cl salt water mainly refers to a saturated sodium chloride solution.

[0011] Preferably, the pH of the feed liquid after the filter residue is added with the Cl-containing brine in step S2 is 2-3. If the pH is greater than 3, hydrochloric acid is added to the feed liquid to make the pH of the feed liquid reach 2-3.

[0012] The chlorine-containing brine after filter pressing in the lead removal process returns to the lead leaching process, which will make the pH greater than 3, and will inhibit the lead leaching effect of sodium chloride. Therefore, HCL needs to be added to the lead leaching solution to adjust the pH.

[0013] Preferably, in step S2, the mixture is stirred and heated to 80-90° C. and kept warm for 15-30 minutes.

[0014] Preferably, when the feed liquid reaches pH 8 in step S3, the feed liquid is taken to analyze the Cl content. If Cl<180 g / L, industrial salt is supplemented to maintain the Cl content in the brine ≥180 g / L.

[0015] The purpose of doing this is to reduce the chlorine content in the chlorine-containing brine returned to the leaching process after filtration, thereby ensuring the solubility of lead in the leaching process.

[0016] Preferably, in step S3, calcium chloride is regularly added to the feed liquid before filter pressing to remove SO4 2 The concentration was adjusted to <5 g / L.

[0017] The purpose of this is to reduce the SO4 in the chlorine-containing brine returned to the lead leaching process after filtration. 2 Concentration <5g / L, SO4 in the lead leaching process 2 High concentrations will inhibit the lead leaching effect of sodium chloride.

[0018] The reactions occurring in the tin and lead separation method of the wet recovery process of tin ash of the present invention mainly include:

[0019] Pb+2Cl=PbCl2

[0020] PbSO4+2NaCl=PbCl2+Na2SO4

[0021] PbCl2+2NaCl=Na2PbCl4

[0022] PbCl2+Ca(OH)2=CaCl2+Pb(OH)2↓

[0023] Na2SO4+Ca(OH)2=2NaOH+CaSO4↓

[0024] SO4 2- +Ca(OH)2=CaSO4↓+2OH -

[0025] SO4 2- +CaCl2=CaSO4↓+2Cl -

[0026] The technical solution of the present invention uses tin smoke ash as raw material, firstly performs sulfuric acid leaching at an appropriate temperature, and utilizes the characteristics of zinc and copper oxides reacting with sulfuric acid to generate soluble substances zinc sulfate ZnSO4 and copper sulfate CuSO4, so that zinc and copper enter the sulfuric acid leaching solution, and realize the separation of zinc, copper and other metals. The leaching rates of zinc and copper reach 90% and 85%, respectively, while the leaching rates of other metals are very low or not leached, forming a slag phase, and the zinc and copper leaching solutions are sent to the zinc and copper production lines for processing. The leached slag phase mainly contains PbO, PbSO4, SnO, SnO2 and SnSO4. The leached slag is added to saturated brine (Cl≥180g / L), and in a saturated sodium chloride (saturated brine) solution, lead ions (Pb 2+ ) and chloride ion (Cl - ) can form a variety of complexes, the stability of these complexes increases with the increase of chloride ion concentration. At higher chloride ion concentrations, lead ions are more inclined to form stable complexes with chloride ions, forming (PbCl4) 2- The complex has a high stability in the solution, making it more difficult for lead ions to precipitate, thereby increasing the solubility of lead ions in the solution. Tin ions do not have this property in chloride-containing salt water, so tin and lead can be separated to obtain tin mud and lead leaching solution, and the leaching rate of tin is greater than 95%. The initial pH of the lead leaching solution is 2-4, and slaked lime is slowly added. The lead ions in the lead leaching solution react with slaked lime to form lead hydroxide precipitate, and sulfate reacts with slaked lime to form calcium sulfate precipitate. In actual production, if sulfate SO4 2- If it is too high, calcium chloride needs to be added regularly to precipitate into sulfate SO4 2- Less than 5g / L, lead mud by-product can be obtained after filtration, the lead leaching rate is ≥75%, and the filtrate is returned to the lead leaching process for recycling.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. The present invention uses a chemical method to separate lead from tin. Compared with the traditional cooling separation physical method, the equipment is simpler, the operation is more convenient, and the energy consumption is more economical. After the lead-tin separation, the grade of the tin mud is greatly improved. The separated lead by-product can also be sold separately, which improves the economic benefits of the wet recovery of tin ash;

[0029] 2. The raw material cost of the present invention is low, and only a small amount of industrial salt and slaked lime need to be added to achieve continuous circulation operation;

[0030] 3. The process of the present invention is simple to operate. No waste water, waste residue and waste gas are generated during the entire process of the lead-tin separation method. It is environmentally friendly and belongs to a green recycling process, which is worthy of promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 : Schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Embodiment 1:

[0034] Take 3 tons of tin ash, the main components (dry basis) are: zinc 16.79%, lead 18.24%, copper 0.91%, tin 12.37%, sodium 5.35%, potassium 1.27%. 3 Prepare 12 ml of sulfuric acid solution with a concentration of 60 g / L in a stirring tank 3 , put tin ash into the reaction system, stir and leach at 60℃ and normal pressure, the end point is stabilized at pH 1-2, the leaching time is 4h, after the reaction, filter the leached material to obtain zinc and copper filtrate and tin-lead mixed residue, the zinc and copper filtrate is sent to zinc and copper production lines for processing; the precipitation rates of tin and lead in the process are both greater than 96%, the tin-lead mixed residue enters the lead leaching process.

[0035] Put the tin-lead mixed residue into a 12m 3 Cl≥180g / L NaCl salt water in a stirred kettle, heated to 85℃, continued constant temperature stirring for 20min, pumped the lead-leached material into a filter press for filtration, and obtained filter residue and filtrate. The main components of the filter residue are tin Sn: 23.3%, Pb: 2.1%, and the recovery rate of tin in the process is greater than 96.2%, which can be directly sold as a product; the filtrate is a mixed solution of lead chloride and sodium chloride, and the filtrate enters the lead removal process;

[0036] The filtrate after lead leaching is put into the lead removal stirring tank, stirred at room temperature and pressure, the stirring speed is set to 60 rpm, the initial pH of the feed liquid is between 2 and 4, and slaked lime is slowly added while stirring. When the pH rises to 8, the addition is stopped and the stirring is continued for 30 minutes. The feed liquid sample is taken to analyze the chlorine content. If Cl<180g / L, the amount of additional industrial salt is calculated and put into the stirring tank; if Cl≥180g / L, no additional operation is required, and the lead-removed material is pumped into the filter press for filtration to obtain filter residue and filtrate. The main component of the filter residue is lead Pb: 42.7%, and the lead recovery rate of the process reaches 82.4%, which can be directly sold as a by-product, and the filtrate is returned to the lead leaching process for recycling.

[0037] Embodiment 2:

[0038] Take 1.5 tons of fly ash, the main components (dry basis) are: zinc 11.81%, lead 25.38%, copper 1.66%, tin 8.16%, sodium 2.54%, potassium 2.75%. 3 Prepare 60g / L sulfuric acid solution in a stirring tank 3 , put tin ash into the reaction mixture, stir and leach at 60℃ and normal pressure, the end point is stabilized at pH 1.5-2, the leaching time is 4h, after the reaction, the leached material is filtered to obtain zinc and copper filtrate and tin-lead mixed residue, the zinc and copper filtrate is sent to zinc and copper production lines for processing; the precipitation rates of tin and lead in the process are both greater than 95%, the tin-lead mixed residue enters the lead leaching process.

[0039] Put the tin-lead mixed residue into a 12m 3 Cl≥180g / L NaCl salt water in a stirred kettle, heated to 90℃, continued constant temperature stirring for 10min, pumped the lead-leached material into a filter press for filtration, and obtained filter residue and filtrate. The main components of the filter residue are tin Sn: 15.6%, Pb: 3.3%, and the recovery rate of tin in the process is 97.1%, which can be directly sold as a product; the filtrate is a mixed solution of lead chloride and sodium chloride, and the filtrate enters the lead removal process;

[0040] The filtrate after lead leaching is put into the lead removal stirring tank, stirred at room temperature and pressure, and slaked lime is slowly added while stirring. When the pH rises to 8.5, the addition is stopped and stirring is continued for 45 minutes. The chlorine content of the feed liquid is analyzed. If Cl<180g / L, the amount of additional industrial salt is calculated and put into the stirring tank; if Cl≥180g / L, no additional operation is required. The lead-removed material is pumped into the filter press for filtration to obtain filter residue and filtrate. The main component of the filter residue is lead Pb: 44.2%. The lead recovery rate of the process reaches 79.5%, which can be directly sold as a by-product, and the filtrate is returned to the lead leaching process for recycling.

[0041] Example 3

[0042] Take 3 tons of ash, the main components (dry basis) are: zinc 8.82%, lead 30.44%, copper 0.72%, tin 10.83%, sodium 1.78%, potassium 3.21%. 3 Prepare 60g / L sulfuric acid solution in a stirring tank 3 , put tin ash into the reaction mixture, stir and leach at 60℃ and normal pressure, the end point is stabilized at pH 1.5-2, the leaching time is 4h, after the reaction, the leached material is filtered to obtain zinc and copper filtrate and tin-lead mixed residue, the zinc and copper filtrate is sent to zinc and copper production lines for processing; the precipitation rates of tin and lead in the process are both greater than 95%, the tin-lead mixed residue enters the lead leaching process.

[0043] Put the tin-lead mixed residue into a 25m 3 Cl≥180g / L NaCl salt water in a stirred kettle, heated to 90℃, continued constant temperature stirring for 20min, pumped the lead-leached material into a filter press for filtration, and obtained filter residue and filtrate. The main components of the filter residue are tin Sn: 26.8%, Pb: 3.1%, and the recovery rate of tin in the process is 96.5%, which can be directly sold as a product; the filtrate is a mixed solution of lead chloride and sodium chloride, and the filtrate enters the lead removal process;

[0044] The filtrate after lead leaching is put into the lead removal stirring tank, stirred at room temperature and pressure, and slaked lime is slowly added while stirring. When the pH rises to 8.5, the addition is stopped and stirring is continued for 45 minutes. The chlorine content of the feed liquid is analyzed. If Cl<180g / L, the amount of additional industrial salt is calculated and put into the stirring tank; if Cl≥180g / L, no additional operation is required. The lead-removed material is pumped into the filter press for filtration to obtain filter residue and filtrate. The main component of the filter residue is lead Pb: 46.4%. The lead recovery rate of the process reaches 77.6%, which can be directly sold as a by-product, and the filtrate is returned to the lead leaching process for recycling.

[0045] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A lead-tin separation method in a wet recovery process of tin ash, characterized in that: The following steps are involved: S1, leaching: adding tin ash to sulfuric acid solution, stirring to leach zinc and copper, and then filtering to obtain zinc- and copper-containing filtrate and filter residue, wherein the filter residue is a tin-lead mixed slag material, and the zinc- and copper-containing filtrate is sent to the zinc and copper production line for post-treatment of extracting copper and zinc; S2, lead leaching: adding the tin-lead mixed slag obtained in step S1 to the prepared chlorine-containing Cl salt water, stirring and heating, and then filtering by pressure to obtain lead chloride salt water and filter residue, wherein the filter residue is tin mud, which can be directly sold as a product; S3, lead removal: slowly add slaked lime Ca(OH)2 to the lead chloride brine obtained in step S2, stir and adjust to pH 8, stop adding, continue stirring for 30-60 min, then filter press to obtain the brine and filter residue after lead removal, the brine after lead removal is returned to the lead leaching process in step S2 for recycling, the filter residue is lead mud, which can be directly sold as a by-product.

2. The lead-tin separation method in a wet recovery process of tin ash according to claim 1, characterized in that: In step S1, the concentration of the sulfuric acid solution is set to 60 g / L, and leaching is carried out at 60° C. and at normal pressure with stirring. The end point is stabilized between pH 1 and 2, and the leaching time is 4 hours.

3. The lead-tin separation method in a wet recovery process of tin ash according to claim 1, characterized in that: In the step S2, the Cl in the chlorine-containing Cl salt water is ≥180 g / L, and the solid-liquid ratio of the tin-lead mixed slag material to the chlorine-containing Cl salt water is set to 1:8-1:

10.

4. The lead-tin separation method in a wet recovery process of tin ash according to claim 1, characterized in that: In step S2, the pH of the feed liquid after the filter residue is added with the Cl-containing brine is 2-3. If the pH is greater than 3, hydrochloric acid is added to the feed liquid to make the pH of the feed liquid reach 2-3.

5. The lead-tin separation method in a wet recovery process of tin ash according to claim 1, characterized in that: In step S2, the mixture is stirred and heated to 80-90° C. and kept warm for 15-30 minutes.

6. The lead-tin separation method in a wet recovery process of tin ash according to claim 1, characterized in that: When the feed liquid reaches pH 8 in step S3, the feed liquid is taken to analyze the Cl content. If Cl<180 g / L, industrial salt is added to maintain the Cl content in the brine ≥180 g / L.

7. The lead-tin separation method in a wet recovery process of tin ash according to claim 1, characterized in that: In step S3, calcium chloride is regularly added to the feed liquid before the filter press to remove SO4 2 The concentration was adjusted to <5g / L.

Images