Electrolysis process for purifying 4N crude tin into 6N high-purity tin

Abstract

The invention relates to an electrolyte for purifying or extracting tin. The electrolyte comprises concentrated sulfuric acid, 4-hydroxybenzenesulfonic acid, hydrazine sulfate, disodium ethylene diamine tetraacetate, tartaric acid, sodium chloride, 2-naphthol and stannous mono-sulphate. According to the method, through multi-dimensional innovation of electrolyte component design-process parameter optimization, key technical bottlenecks such as deep impurity removal, deposition layer densification and process stability control in the high-purity tin electrolysis purification process are successfully broken through, and indexes such as product purity, production efficiency and process stability all meet existing industrial standards; and a process with higher purification efficiency is provided for high-purity tin applied to the high-end manufacturing industry fields of semiconductor packaging, photovoltaic welding strips and the like.

Description

Technical Field

[0001] The present invention belongs to the field of metal material extraction, and relates to an electrolyte for purifying or extracting tin and its application, in particular to an electrolysis process for purifying 4N crude tin to 6N high-purity tin using this electrolyte. Background Art

[0002] High-purity tin (purity ≥ 99.9999%) is an irreplaceable strategic emerging material in the fields of aerospace precision devices, semiconductor packaging solders, and high-density integrated circuit manufacturing. In the current field of high-purity tin purification, the main purification methods include physical means such as Czochralski crystal pulling, vacuum distillation, and zone melting. However, there are significant bottlenecks in existing physical purification technologies: for example, the vacuum distillation - directional solidification combined process disclosed in "Research on the Preparation of High-Purity Tin by Vacuum Distillation - Zone Melting" can improve the purity of tin, but the purity it can currently achieve is at the 4N level, and its single processing cycle is as long as 120 hours. These methods generally face technical and economic defects such as high energy consumption, harsh operating environments (such as requiring high vacuum), and difficulties in large-scale production.

[0003] Electrolytic refining, as a classic method for metal purification, has been industrially applied in the 6N-level purification of metals such as copper and nickel, but in the field of tin purification, it has long been limited to crude tin purification (3N → 4N) and secondary resource recovery. There are two major technical obstacles in traditional tin electrolysis systems: (1) the problem of electrolyte turbidity caused by the hydrolysis of tin ions, which forces the electrolytic cell to be equipped with a complex filtration system; (2) the phenomenon that trace impurities such as Fe and Cu preferentially deposit at the cathode, resulting in contamination of the target product. These problems have led to the fact that existing electrolysis technologies have always been unable to break through the 5N purity threshold, objectively forming an industrial pattern in which physical purification methods monopolize the production of high-purity tin.

[0004] In view of this, it is urgent to develop a new type of electrolytic purification system, which can achieve breakthroughs in comprehensive performance such as simplified process flow (single electrolysis reaching the standard), reduced equipment investment, and production energy consumption control while ensuring a 6N-level ultra-high purity, so as to fundamentally reverse the passive situation of relying on imports for high-purity tin in our country.

[0005] The present invention uses 4N crude tin as the raw material and can obtain 6N high-purity tin only through one electrolysis and vacuum ingot casting, overcoming the disadvantages of long cycle and high cost of physical purification means. For the first time, the tin electrolysis process is used for the purification of 6N high-purity tin, innovating the purification method of high-purity tin. The process provided by the present invention has low input costs and low operating energy consumption, and has strong competitive advantages.

[0006] In addition, on the one hand, there are differences in the understanding of those skilled in the art; on the other hand, when the inventor made this invention, a large number of documents and patents were studied, but due to space limitations, all details and content were not listed in detail. However, this does not mean that this invention does not possess the features of these prior arts. On the contrary, this invention already possesses all the features of the prior arts, and the applicant reserves the right to add relevant prior arts in the background art. Summary of the Invention

[0007] One object of the present invention is to provide an electrolytic solution for purifying or extracting tin, which is selected from the following group:

[0008] Concentrated sulfuric acid, phenol sulfonic acid, hydrazine sulfate, disodium ethylenediaminetetraacetate, tartaric acid, sodium chloride, 2-naphthol, stannous sulfate;

[0009] Concentrated sulfuric acid, 4-hydroxybenzenesulfonic acid, hydrazine sulfate, disodium ethylenediaminetetraacetate, tartaric acid, sodium chloride, 2-naphthol, stannous sulfate.

[0010] According to a preferred embodiment, the electrolytic solution contains:

[0011] Hydrazine sulfate, 1 - 10 g / L;

[0012] Disodium ethylenediaminetetraacetate, 1 - 10 g / L;

[0013] Tartaric acid, 1 - 10 g / L; and

[0014] Sodium chloride, 5 - 30 g / L.

[0015] According to a preferred embodiment, the electrolytic solution contains:

[0016] Phenol sulfonic acid or 4-hydroxybenzenesulfonic acid, 30 - 60 g / L;

[0017] Stannous sulfate, 40 - 70 g / L;

[0018] Concentrated sulfuric acid, 50 - 100 g / L; and

[0019] 2-naphthol, 0.1 - 1 g / L.

[0020] According to a preferred embodiment, the electrolytic solution contains:

[0021] Hydrazine sulfate, 1 - 10 g / L;

[0022] Disodium ethylenediaminetetraacetate, 1 - 10 g / L;

[0023] Tartaric acid, 1 - 10 g / L;

[0024] Sodium chloride, 5 - 30 g / L;

[0025] Phenolsulfonic acid or 4 - hydroxybenzenesulfonic acid, 30 - 60 g / L; and

[0026] Tin(II) sulfate, 40 - 70 g / L.

[0027] According to a preferred embodiment, the electrolyte comprises:

[0028] Hydrazine sulfate, 1 - 10 g / L;

[0029] Disodium ethylenediaminetetraacetate, 1 - 10 g / L;

[0030] Tartaric acid, 1 - 10 g / L;

[0031] Sodium chloride, 5 - 30 g / L;

[0032] Phenolsulfonic acid or 4 - hydroxybenzenesulfonic acid, 30 - 60 g / L;

[0033] Tin(II) sulfate, 40 - 70 g / L; and

[0034] 2 - naphthol, 0.1 - 1 g / L.

[0035] Preferably, the electrolyte comprises 1 g / L of hydrazine sulfate. The electrolyte comprises 2 g / L of hydrazine sulfate. The electrolyte comprises 3 g / L of hydrazine sulfate. The electrolyte comprises 4 g / L of hydrazine sulfate. The electrolyte comprises 5 g / L of hydrazine sulfate. The electrolyte comprises 6 g / L of hydrazine sulfate. The electrolyte comprises 7 g / L of hydrazine sulfate. The electrolyte comprises 8 g / L of hydrazine sulfate. The electrolyte comprises 9 g / L of hydrazine sulfate. The electrolyte comprises 10 g / L of hydrazine sulfate.

[0036] Preferably, the electrolyte comprises 1 g / L of disodium ethylenediaminetetraacetate. The electrolyte comprises 2 g / L of disodium ethylenediaminetetraacetate. The electrolyte comprises 3 g / L of disodium ethylenediaminetetraacetate. The electrolyte comprises 4 g / L of disodium ethylenediaminetetraacetate. The electrolyte comprises 5 g / L of disodium ethylenediaminetetraacetate. The electrolyte comprises 6 g / L of disodium ethylenediaminetetraacetate. The electrolyte comprises 7 g / L of disodium ethylenediaminetetraacetate. The electrolyte comprises 8 g / L of disodium ethylenediaminetetraacetate. The electrolyte comprises 9 g / L of disodium ethylenediaminetetraacetate. The electrolyte comprises 10 g / L of disodium ethylenediaminetetraacetate.

[0037] Preferably, the electrolyte comprises 1 g / L of tartaric acid. The electrolyte comprises 2 g / L of tartaric acid. The electrolyte comprises 3 g / L of tartaric acid. The electrolyte comprises 4 g / L of tartaric acid. The electrolyte comprises 5 g / L of tartaric acid. The electrolyte comprises 6 g / L of tartaric acid. The electrolyte comprises 7 g / L of tartaric acid. The electrolyte comprises 8 g / L of tartaric acid. The electrolyte comprises 9 g / L of tartaric acid. The electrolyte comprises 10 g / L of tartaric acid.

[0038] Preferably, the electrolyte contains 3 g / L of sodium chloride. The electrolyte contains 4 g / L of sodium chloride. The electrolyte contains 5 g / L of sodium chloride. The electrolyte contains 6 g / L of sodium chloride. The electrolyte contains 7 g / L of sodium chloride. The electrolyte contains 8 g / L of sodium chloride. The electrolyte contains 9 g / L of sodium chloride. The electrolyte contains 10 g / L of sodium chloride. The electrolyte contains 15 g / L of sodium chloride. The electrolyte contains 20 g / L of sodium chloride. The electrolyte contains 25 g / L of sodium chloride. The electrolyte contains 30 g / L of sodium chloride.

[0039] Preferably, the electrolyte contains 30 g / L of phenolsulfonic acid or 4-hydroxybenzenesulfonic acid. The electrolyte contains 35 g / L of phenolsulfonic acid or 4-hydroxybenzenesulfonic acid. The electrolyte contains 40 g / L of phenolsulfonic acid or 4-hydroxybenzenesulfonic acid. The electrolyte contains 45 g / L of phenolsulfonic acid or 4-hydroxybenzenesulfonic acid. The electrolyte contains 50 g / L of phenolsulfonic acid or 4-hydroxybenzenesulfonic acid. The electrolyte contains 55 g / L of phenolsulfonic acid or 4-hydroxybenzenesulfonic acid. The electrolyte contains 60 g / L of phenolsulfonic acid or 4-hydroxybenzenesulfonic acid.

[0040] Preferably, the electrolyte contains 0.2 g / L of 2-naphthol. The electrolyte contains 0.1 g / L of 2-naphthol. The electrolyte contains 0.3 g / L of 2-naphthol. The electrolyte contains 0.4 g / L of 2-naphthol. The electrolyte contains 0.5 g / L of 2-naphthol.

[0041] Preferably, the electrolyte contains 40 g / L of stannous sulfate. The electrolyte contains 45 g / L of stannous sulfate. The electrolyte contains 50 g / L of stannous sulfate. The electrolyte contains 55 g / L of stannous sulfate. The electrolyte contains 60 g / L of stannous sulfate. The electrolyte contains 65 g / L of stannous sulfate. The electrolyte contains 70 g / L of stannous sulfate.

[0042] More preferably, the electrolyte is configured as follows: add 400 g of 4-hydroxybenzenesulfonic acid, 20 g of hydrazine sulfate, 20 g of disodium ethylenediaminetetraacetate, 5 g of tartaric acid, 100 g of sodium chloride, 2 g of 2-naphthol, and 450 g of stannous sulfate to every 10 L of water.

[0043] The electrolyte is configured as follows: add 210 g of 4-hydroxybenzenesulfonic acid, 20 g of hydrazine sulfate, 20 g of disodium ethylenediaminetetraacetate, 5 g of tartaric acid, 100 g of sodium chloride, 2 g of 2-naphthol, and 280 g of stannous sulfate to every 10 L of water.

[0044] The electrolyte is configured as follows: add 420 g of 4-hydroxybenzenesulfonic acid, 20 g of hydrazine sulfate, 20 g of disodium ethylenediaminetetraacetate, 5 g of tartaric acid, 100 g of sodium chloride, 2 g of 2-naphthol, and 490 g of stannous sulfate to every 10 L of water.

[0045] According to a preferred embodiment, the electrolyte further contains concentrated sulfuric acid. The electrolyte contains:

[0046] Hydrazine sulfate, 1 - 10 g / L;

[0047] Disodium ethylenediaminetetraacetate, 1 - 10 g / L;

[0048] Tartaric acid, 1 - 10 g / L;

[0049] Sodium chloride, 5 - 30 g / L;

[0050] Phenolsulfonic acid or 4 - Hydroxybenzenesulfonic acid, 30 - 60 g / L;

[0051] Stannous sulfate, 40 - 70 g / L;

[0052] 2 - Naphthol, 0.1 - 1 g / L; and

[0053] Concentrated sulfuric acid, 50 - 100 g / L.

[0054] Preferably, the electrolyte contains 50 g / L of concentrated sulfuric acid. The electrolyte contains 70 g / L of concentrated sulfuric acid. The electrolyte contains 100 g / L of concentrated sulfuric acid.

[0055] According to a preferred embodiment, the electrolyte further contains gelatin. The electrolyte contains:

[0056] Hydrazine sulfate, 1 - 10 g / L;

[0057] Disodium ethylenediaminetetraacetate, 1 - 10 g / L;

[0058] Tartaric acid, 0.5 - 10 g / L;

[0059] Sodium chloride, 5 - 30 g / L;

[0060] Phenolsulfonic acid or 4 - Hydroxybenzenesulfonic acid, 30 - 60 g / L;

[0061] Stannous sulfate, 40 - 70 g / L;

[0062] 2 - Naphthol, 0.1 - 1 g / L;

[0063] Concentrated sulfuric acid, 50 - 100 g / L; and

[0064] Gelatin, 0.5 - 5 g / L.

[0065] More preferably, the electrolyte contains 0.5 g / L of gelatin. The electrolyte contains 1 g / L of gelatin. The electrolyte contains 1.5 g / L of gelatin. The electrolyte contains 2 g / L of gelatin. The electrolyte contains 3 g / L of gelatin. The electrolyte contains 4 g / L of gelatin. The electrolyte contains 5 g / L of gelatin.

[0066] One of the objects of the present invention is to provide the use of the electrolyte involved in the present invention in the extraction or purification of tin.

[0067] One of the purposes of the present invention is to provide a preparation method of purified tin.

[0068] One of the purposes of the present invention is to provide an electrolysis process for purifying 4N crude tin to 6N high-purity tin, and the electrolysis process includes the following steps:

[0069] Using titanium, stainless steel or 6N pure tin as the cathode plate, and the tin to be treated as the anode plate;

[0070] Immerse the cathode plate and the anode plate into the electrolyte involved in the present application for electrolysis.

[0071] According to a preferred embodiment, the electrolysis process includes:

[0072] (1) Mix concentrated sulfuric acid and pure water;

[0073] (2) Sequentially add the electrolyte involved in the present application and stir until dissolved;

[0074] (3) Dissolve gelatin and mix the dissolved gelatin into the mixture in step (2).

[0075] According to a preferred embodiment, during electrolysis, the electrolyte maintains a flow rate of 0.5 - 2 L / min. Preferably, the electrolyte maintains a flow rate of 0.5 L / min. The electrolyte maintains a flow rate of 1 L / min. The electrolyte maintains a flow rate of 2 L / min.

[0076] According to a preferred embodiment, the magnitude of the electrolysis current is 20 - 60 A. Preferably, the magnitude of the current is 20 A. Preferably, the magnitude of the current is 30 A. Preferably, the magnitude of the current is 40 A. Preferably, the magnitude of the current is 50 A.

[0077] According to a preferred embodiment, the electrolysis process further includes:

[0078] Repeat the step of "immersing the cathode plate and the anode plate into the electrolyte involved in the present application for electrolysis", and obtain the purified tin at the end of each electrolysis.

[0079] According to a preferred embodiment, the distance between the cathode plate and the anode plate can be 3 - 7 cm. Preferably, the distance between the plates can be 3 cm. Preferably, the distance between the plates can be 4 cm. Preferably, the distance between the plates can be 5 cm. Preferably, the distance between the plates can be 6 cm. Preferably, the distance between the plates can be 7 cm.

[0080] The technical solution provided by the present invention realizes the efficient purification of high-purity tin and the deep removal of impurities through the optimization of the electrolyte formula and the coordinated regulation of process parameters. Specifically, the beneficial effects of this technical solution are as follows:

[0081] 1. Electrolyte system based on multi-element synergistic removal

[0082] The present invention systematically proposes a composite complexing electrolyte system, especially for impurities such as Pb, Bi, Fe, As, Sb, Ge, etc. that are difficult to remove by traditional processes. Specific complexing agents and precipitants are introduced to form a synergistic impurity removal mechanism. After GDMS detection, the contents of 12 key impurity elements such as Mg, Al, Ca, Co, Ni, Cu, Zn, As, Ag, In, Sb, Au, etc. in the purified tin ingot are all lower than 0.005 ppm (detection limit). Among them, the residual amounts of As and Sb are reduced by two orders of magnitude compared with the traditional process, achieving a breakthrough in the single electrolytic purification of 4N grade crude tin to 6N grade (purity ≥ 99.9999%).

[0083] Since 6N grade tin has been greatly improved in terms of conductivity, thermal conductivity, corrosion resistance, welding performance, etc. compared with 4N grade crude tin, the application range of 6N grade tin is wider than that of 4N grade crude tin in the semiconductor field and optoelectronic field. Therefore, the technical solution of the present invention further expands the application range of tin.

[0084] 2. Electrolysis process with directional flow field control

[0085] By adjusting the electrolyte flow rate (0.5 - 2 L / min) and electrolysis current (20 - 60 A) of the present invention, the electrolyte forms a laminar flow state and is evenly distributed between the anode and cathode, and the fluctuation of the tin ion concentration gradient between the anode and cathode is reduced. The electrolysis process under this process not only promotes the improvement of the tin ion migration rate, but also reduces the surface roughness (Ra) of the cathode deposition layer compared with the traditional process, thereby effectively suppressing the mechanical inclusion of impurity particles and improving the purity of the extracted tin.

[0086] 3. Process synergy optimization of low current density - high filtration accuracy

[0087] Electrolysis is carried out at a low current density of 20 - 60 A to achieve a dynamic balance between the cathode deposition rate and the grain growth rate. Cooperating with a 2000-mesh polypropylene anode bag to construct a physical barrier, the interception efficiency of anode mud is ≥ 99%, and the electrolyte turbidity is stably maintained at a level that can effectively repeat at least 3 electrolysis operations, fundamentally eliminating the risk of secondary pollution caused by the backmixing of anode mud.

[0088] Generally speaking, through multi-dimensional innovations such as "electrolyte component design - process parameter optimization", the present invention successfully breaks through the key technical bottlenecks such as deep impurity removal, densification of the deposition layer, and process stability control in the electrolytic purification of high-purity tin. The indicators such as product purity, production efficiency, and process stability all significantly meet the industry standards, providing a process with higher purification efficiency for high-purity tin applied in high-end manufacturing fields such as semiconductor packaging and photovoltaic solder tapes. Detailed implementation mode

[0089] In the description of the present invention, the terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined.

[0090] Example 1

[0091] This example relates to an electrolyte for electrolyzing non-ferrous metals. This example also relates to an electrolyte for purifying non-ferrous metals. This example also relates to an electrolyte for electrolyzing tin. This example also relates to an electrolyte for purifying or extracting tin.

[0092] The preparation method of the electrolyte comprises:

[0093] (1) Mix 5 kg of concentrated sulfuric acid and 80 L of pure water;

[0094] (2) Sequentially add 3 kg of 4-hydroxybenzenesulfonic acid, 1 kg of hydrazine sulfate, 1 kg of disodium ethylenediaminetetraacetate, 50 g of tartaric acid, 1 kg of sodium chloride, 10 g of 2-naphthol, 4 kg of stannous sulfate, and 50 g of gelatin, and stir until dissolved;

[0095] (3) When in use, make up the volume of the electrolyte to 100 L.

[0096] Example 2

[0097] The preparation method of the electrolyte comprises:

[0098] (1) Mix 7 kg of concentrated sulfuric acid and 80 L of pure water;

[0099] (2) Sequentially add 4 kg of 4-hydroxybenzenesulfonic acid, 200 g of hydrazine sulfate, 200 g of disodium ethylenediaminetetraacetate, 50 g of tartaric acid, 1 kg of sodium chloride, 20 g of 2-naphthol, 4.5 kg of stannous sulfate, and 100 g of gelatin, and stir until dissolved;

[0100] (3) When in use, make up the volume of the electrolyte to 100 L.

[0101] Example 3

[0102] The preparation method of the electrolyte comprises the following steps:

[0103] (1) Mix 10 kg of concentrated sulfuric acid and 80 L of pure water;

[0104] (2) Sequentially add 6 kg of 4-hydroxybenzenesulfonic acid, 100 g of hydrazine sulfate, 100 g of disodium ethylenediaminetetraacetate, 40 g of tartaric acid, 500 g of sodium chloride, 15 g of 2-naphthol, 3.2 kg of stannous sulfate, and 500 g of gelatin, and stir until dissolved;

[0105] (3) The electrolyte was made up to 100 L.

[0106] Example 4

[0107] The preparation method of the electrolyte comprises the following steps:

[0108] (1) 7 kg of concentrated sulfuric acid was mixed with 80 L of pure water;

[0109] (2) 4 kg of 4-hydroxybenzenesulfonic acid, 200 g of hydrazine sulfate, 200 g of disodium ethylenediaminetetraacetate, 50 g of tartaric acid, 1 kg of sodium chloride, 20 g of 2-naphthol, 4.5 kg of stannous sulfate, and 100 g of gelatin were sequentially added and stirred until dissolved;

[0110] (3) The electrolyte was made up to 100 L.

[0111] Example 5

[0112] The preparation method of the electrolyte comprises the following steps:

[0113] (1) 10 kg of concentrated sulfuric acid was mixed with 80 L of pure water;

[0114] (2) 6 kg of 4-hydroxybenzenesulfonic acid, 100 g of hydrazine sulfate, 100 g of disodium ethylenediaminetetraacetate, 40 g of tartaric acid, 500 g of sodium chloride, 15 g of 2-naphthol, 3.2 kg of stannous sulfate, and 500 g of gelatin were sequentially added and stirred until dissolved;

[0115] (3) The electrolyte was made up to 100 L.

[0116] Example 6

[0117] The preparation method of the electrolyte comprises the following steps:

[0118] (1) 8 kg of concentrated sulfuric acid was mixed with 80 L of pure water;

[0119] (2) 4.8 kg of 4-hydroxybenzenesulfonic acid, 800 g of hydrazine sulfate, 800 g of disodium ethylenediaminetetraacetate, 1 kg of tartaric acid, 3 kg of sodium chloride, 100 g of 2-naphthol, 7 kg of stannous sulfate, and 200 g of gelatin were sequentially added and stirred until dissolved;

[0120] (3) The electrolyte was made up to 100 L.

[0121] Example 7

[0122] This embodiment relates to a preparation method of purified tin. This embodiment also relates to a purification method of tin. This embodiment also relates to an extraction method of tin. This embodiment also relates to an extraction method of non-ferrous metals. This embodiment also relates to a purification method of non-ferrous metals. This embodiment relates to an electrolysis process for purifying 4N crude tin to 6N high-purity tin.

[0123] The preparation method of purified tin includes:

[0124] (1) Using titanium as the cathode plate and the tin to be treated as the anode plate, and using a circulation pump to circulate the electrolyte involved in any one of Embodiments 1 to 6 in the electrolytic cell at a speed of 0.5, 1 or 2 L / min.

[0125] (2) Setting the power controller to the constant current mode with a current magnitude of 20, 40 or 60 A, and then starting the electrolysis.

[0126] Example 8

[0127] This embodiment relates to a preparation method of purified tin. This embodiment also relates to a purification method of tin. This embodiment also relates to an extraction method of tin. This embodiment also relates to an extraction method of non-ferrous metals. This embodiment also relates to a purification method of non-ferrous metals. This embodiment relates to an electrolysis process for purifying 4N crude tin to 6N high-purity tin.

[0128] The method for purifying tin (the electrolysis process for purifying 4N crude tin to 6N high-purity tin) includes:

[0129] (1) Adding about 70 L of pure water into the tank, and then slowly adding 7 kg of concentrated sulfuric acid while stirring.

[0130] (2) Then sequentially adding 4 kg of 4-hydroxybenzenesulfonic acid, 200 g of hydrazine sulfate, 200 g of disodium ethylenediaminetetraacetate, 50 g of tartaric acid, 1 kg of sodium chloride, 20 g of 2-naphthol, and 4.5 kg of stannous sulfate. After adding the above reagents, stir to dissolve.

[0131] (3) Putting 100 g of gelatin into a beaker containing 1 L of pure water, and then putting the beaker into a water bath at 50 °C for heating and dissolving. After dissolution, mix it with the solution in step (2).

[0132] (4) Adding pure water into the tank to the 100 L scale, and then stirring evenly to complete the preparation of the electrolyte.

[0133] (5) Putting a Teflon strip around the periphery of 5 cathode plates made of titanium and cleaning them with pure water.

[0134] (6) After washing 6 cast tin anode plates with a purity of 4N with dilute hydrochloric acid - pure water, put on anode bags with 2000 meshes.

[0135] (7) Place the processed cathode plates and anode plates in the electrolytic cell in an alternating pattern with a pole spacing of 3 cm.

[0136] (8) Use a circulating pump to circulate the electrolyte in the electrolytic cell at a speed of 0.5 L / min.

[0137] (9) Set the power controller to the constant current mode with a current magnitude of 20 A, and then start electrolysis.

[0138] (10) After 10 days of electrolysis, peel off the tin sheets on the cathode plate, wash them clean with water, and then weigh about 2 kg of tin sheets and put them into a vacuum furnace for ingot casting to obtain high-purity tin ingots with a purity of 6N.

[0139] Example 9

[0140] A method for purifying tin (an electrolysis process for purifying 4N crude tin to 6N high-purity tin) includes:

[0141] (1) Add about 70 L of pure water into the tank, and then slowly add 7 kg of concentrated sulfuric acid while stirring.

[0142] (2) Then add 4 kg of 4-hydroxybenzenesulfonic acid, 200 g of hydrazine sulfate, 200 g of disodium ethylenediaminetetraacetate, 50 g of tartaric acid, 1 kg of sodium chloride, 20 g of 2-naphthol, and 4.5 kg of stannous sulfate in sequence. After adding the above reagents, stir to dissolve.

[0143] (3) Put 100 g of gelatin into a beaker containing 1 L of pure water, and then place the beaker in a water bath at 50 °C for heating and dissolving. After dissolution, mix it with the solution in step (2).

[0144] (4) Add pure water into the tank to the 100 L scale mark, and then stir evenly. The electrolyte is thus prepared.

[0145] (5) Put four-fluorine strips around the five cathode plates made of titanium and wash them clean with pure water.

[0146] (6) For six cast tin anode plates with a purity of 4N, after cleaning with dilute hydrochloric acid - pure water, put on anode bags with 2000 meshes.

[0147] (7) Place the processed cathode plates and anode plates in the electrolytic cell in an alternating pattern with a pole spacing of 7 cm.

[0148] (8) Use a circulating pump to circulate the electrolyte in the electrolytic cell at a speed of 2 L / min.

[0149] (9) Set the power controller to the constant current mode with a current magnitude of 60 A, and then start electrolysis.

[0150] (10) After 10 days of electrolysis, the tin sheets on the cathode plate are peeled off, washed clean with clear water, and then about 2 kg of tin sheets are weighed and put into a vacuum furnace for ingot casting to obtain a high-purity tin ingot with a purity of 6N.

[0151] Example 10

[0152] The method for purifying tin (the electrolysis process for purifying 4N crude tin to 6N high-purity tin) includes:

[0153] (1) Add about 70 L of pure water into the tank, and then slowly add 7 kg of concentrated sulfuric acid while stirring.

[0154] (2) Then add 4 kg of 4-hydroxybenzenesulfonic acid, 200 g of hydrazine sulfate, 200 g of disodium ethylenediaminetetraacetate, 50 g of tartaric acid, 1 kg of sodium chloride, 20 g of 2-naphthol, and 4.5 kg of stannous sulfate in sequence. After adding the above reagents, stir to dissolve.

[0155] (3) Put 100 g of gelatin into a beaker containing 1 L of pure water, and then put the beaker into a water bath at 50 °C for heating and dissolving. After dissolution, mix it with the solution in step (2).

[0156] (4) Add pure water into the tank to the 100 L scale, and then stir evenly to complete the preparation of the electrolyte.

[0157] (5) Put Teflon strips around the five cathode plates made of titanium and wash them clean with pure water.

[0158] (6) For the six cast tin anode plates with a purity of 4N, after cleaning with dilute hydrochloric acid - pure water, put on anode bags with a mesh size of 2000.

[0159] (7) Place the treated cathode plates and anode plates in the electrolytic cell alternately with a pole spacing of 5 cm.

[0160] (8) Use a circulation pump to circulate the electrolyte in the electrolytic cell at a speed of 1 L / min.

[0161] (9) Set the power controller to the constant current mode with a current of 40 A, and then start electrolysis.

[0162] (10) After 10 days of electrolysis, the tin sheets on the cathode plate are peeled off, washed clean with clear water, and then about 2 kg of tin sheets are weighed and put into a vacuum furnace for ingot casting to obtain a high-purity tin ingot with a purity of 6N.

[0163] Example 11

[0164] Carry out electrolysis in three rounds according to the electrolysis steps in Example 10. Each round of electrolysis lasts for 10 days. Based on this operation, 15 kg of cathode tin is obtained on average for each round.

[0165] The cathode tin ingots obtained in each round are analyzed and detected. The analysis and detection are carried out using a glow discharge mass spectrometer (GDMS). The detection results are shown in Table 1.

[0166] Table 1 Result comparison table (units are all ppm)

[0167] Element Raw material The first round The second round The third round Mg - ＜0.005 ＜0.005 ＜0.005 Al 4.2 ＜0.005 ＜0.005 ＜0.005 Ca - ＜0.01 ＜0.01 ＜0.01 Fe 22.1 0.011 0.021 0.028 Co 2.1 ＜0.005 ＜0.005 ＜0.005 Ni 1.9 ＜0.005 ＜0.005 ＜0.005 Cu 3.8 ＜0.005 ＜0.005 ＜0.005 Zn 3.2 ＜0.005 ＜0.005 ＜0.005 As 2.7 ＜0.005 ＜0.005 ＜0.005 Ag 4.1 ＜0.005 ＜0.005 ＜0.005 In - ＜0.05 ＜0.05 ＜0.05 Sb 16.1 ＜0.05 ＜0.05 ＜0.05 Au - ＜0.005 ＜0.005 ＜0.005 Pb 18.9 0.021 0.041 0.039 Bi 12.0 0.017 0.026 0.030

[0168] Based on the results in Table 1, it can be seen that using the preparation method provided by the present invention, 4N crude tin can be electrolytically purified to 6N at one time. At the same time, using this preparation method, impurity elements such as Mg, Al, Ca, Co, Ni, Cu, Zn, As, Ag, In, Sb, and Au can be removed, so that the contents of impurity elements such as Mg, Al, Ca, Co, Ni, Cu, Zn, As, Ag, In, Sb, and Au in the purified tin are lower than the detection limit of the mass spectrometer. This result shows that the preparation method provided by the present invention has a significant effect on purifying crude tin.

[0169] It should be noted that the above specific embodiments are exemplary. Those skilled in the art can come up with various solutions inspired by the disclosed content of the present invention, and these solutions also belong to the disclosure scope of the present invention and fall within the protection scope of the present invention. Those skilled in the art should understand that the specification of the present invention is illustrative and does not constitute a limitation on the claims. The protection scope of the present invention is defined by the claims and their equivalents.

Claims

1. An electrolyte, characterized in that: The electrolyte is selected from the following group: Concentrated sulfuric acid, phenolsulfonic acid, hydrazine sulfate, disodium ethylenediaminetetraacetate, tartaric acid, sodium chloride, 2-naphthol, stannous sulfate; Concentrated sulfuric acid, 4-hydroxybenzenesulfonic acid, hydrazine sulfate, disodium ethylenediaminetetraacetate, tartaric acid, sodium chloride, 2-naphthol, stannous sulfate.

2. The electrolyte according to claim 1, characterized in that The electrolyte comprises: Hydrazine sulfate, 1-10 g / L; Disodium ethylenediaminetetraacetate, 1-10 g / L; Tartaric acid, 0.5-10 g / L; and Sodium chloride, 5-30g / L.

3. The electrolyte according to claim 1 or 2, characterized in that The electrolyte comprises: Phenolsulfonic acid or 4-hydroxybenzenesulfonic acid, 30-60 g / L; Stannous sulfate, 40-70 g / L; Concentrated sulfuric acid, 50-100 g / L; and 2-Naphthol, 0.1~1g / L.

4. The electrolyte according to any one of claims 1 to 3, characterized in that: The electrolyte solution is configured as follows: 400 g of 4-hydroxybenzenesulfonic acid, 20 g of hydrazine sulfate, 20 g of disodium ethylenediaminetetraacetate, 5 g of tartaric acid, 100 g of sodium chloride, 2 g of 2-naphthol, and 450 g of stannous sulfate are added to every 10 L of water.

5. The electrolyte according to any one of claims 1 to 3, characterized in that: The electrolyte solution is configured as follows: 400 g of phenolsulfonic acid, 20 g of hydrazine sulfate, 20 g of disodium ethylenediaminetetraacetate, 5 g of tartaric acid, 100 g of sodium chloride, 2 g of 2-naphthol, and 450 g of stannous sulfate are added to every 10 L of water.

6. The electrolyte according to any one of claims 1 to 5, characterized in that: The electrolyte also contains gelatin.

7. Use of the electrolyte according to any one of claims 1 to 6 in extracting or purifying tin.

8. An electrolytic process for purifying 4N crude tin to 6N high-purity tin, characterized in that: The electrolysis process consists of the following steps: Titanium, stainless steel or 6N pure tin is used as the cathode plate, and the tin to be treated is used as the anode plate; The cathode plate and the anode plate are immersed in the electrolyte according to any one of claims 1 to 6, and electrolysis is performed at a current of 20 to 60 A and an electrolyte flow rate of 0.5 to 2 L / min.

9. The electrolysis process according to claim 8, characterized in that: When electrolysis is performed, the electrolysis conditions are: a current of 40A and an electrolyte flow rate of 1L / min.

10. The electrolysis process according to claim 8 or 9, characterized in that: The electrolysis process further comprises: The step of "immersing the cathode plate and the anode plate in the electrolyte as claimed in any one of claims 1 to 6 for electrolysis" is repeated, and purified tin is obtained at the end of each electrolysis.