CN119571084A - Method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate - Google Patents
Method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate Download PDFInfo
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Abstract
The invention discloses a method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate, which comprises the following steps of firstly, liquid preparation; preparing electrolyte, electrolyzing, removing copper and refining, and vacuum distilling. According to the invention, crude tin is prepared into electrolyte and added with benzene sulfonate for electrolysis, so that the precipitation potential of lead and tin is changed, and further, the impurity lead element with high difficulty is removed, and other impurity elements in the crude tin can be removed, and the lead, copper element and other impurity elements are further removed by combining copper removal refining and vacuum distillation, so that the 5N or 6N standard high-purity tin is obtained, the content of lead element and bismuth element is less than 1ppm, the content of uranium element and thorium element is less than 1ppb, the requirements of low alpha-ray materials are met, the problem that the radioactive alpha-particle impurity elements in the crude tin are difficult to remove by an electrolysis method is effectively solved, and the high-purity tin is used as the use requirement of solder, so that the quality of a semiconductor chip is greatly improved.
Description
Technical Field
The invention belongs to the technical field of preparation of high-purity metal materials with low alpha-ray quantity for manufacturing electronic parts, and particularly relates to a method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzene sulfonate.
Background
Tin is a low melting point metal with silvery white luster, and is widely applied to industries such as electronics, information, electrical appliances, chemical industry, metallurgy, building materials, machinery, food packaging and the like. The high-purity tin has the excellent characteristics of soft texture, low melting point, strong expansibility, strong plasticity, no toxicity and the like, and is mainly used for preparing basic materials such as compound semiconductors, high-purity alloys, ultralow-temperature cooling alloys, superconducting materials, solders, doping agents of the compound semiconductors, targets and the like.
With the continued advancement and development of electronic information, the printed package production of semiconductors has also progressed rapidly, and the need for printed solder paste or related solder paste products has increased substantially. However, in the semiconductor device with high density and high capacity, the risk of soft errors caused by the influence of alpha rays from tin materials near the semiconductor chip is increased, so that the quality requirement on the product is more strict, and simultaneously, the purification technology and process of the high-purity low-alpha-ray tin materials are more highly required, especially, the heavy metal impurity elements (such as lead and bismuth) which are easy to generate alpha decay must be less than 1ppm, and the radioactive elements (such as uranium and thorium) must be less than 1ppb.
Currently, the main method for preparing high purity tin is electrorefining. In the electrolytic process, elements difficult to remove mainly comprise lead, iron, copper, arsenic, antimony, bismuth and the like, wherein the potentials of lead, bismuth and copper ions are relatively close to those of tin, the tin is difficult to purify to high purity by adopting an electrolytic means, the conventional electrolytic refining technology has poor effect of removing trace impurities such as lead, copper and the like, and the lead and copper elements can be effectively removed by combining the copper removal refining technology and the vacuum distillation technology.
Thus, there is a need for a method of removing metallic impurities by electrolytic coupling vacuum distillation of tin benzene sulfonate.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzene sulfonate aiming at the defects in the prior art. According to the method, crude tin is prepared into electrolyte, and benzenesulfonate is added for electrolysis, so that the precipitation potential of lead and tin is changed, and further, the lead element with high difficulty is removed, in addition, other impurity elements in the crude tin can be removed, and then, the lead element, copper element and other impurity elements are further removed by combining copper removal refining and vacuum distillation, so that the tin with low alpha-ray quantity and high purity is prepared.
In order to solve the technical problems, the technical scheme adopted by the invention is that the method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzene sulfonate is characterized by comprising the following steps:
Heating and melting 2N-4N crude tin, extracting with water to obtain tin beads, adding the tin beads into a dilute sulfuric acid solution, heating and dissolving, and finally performing solid-liquid separation to obtain a stannous sulfate solution;
Preparing an electrolyte, namely adding concentrated sulfuric acid, benzenesulfonate, resveratrol, naphthol, gelatin, hydroquinone and deionized water into the stannous sulfate solution obtained in the step one to obtain the electrolyte, wherein the electrolyte comprises 40-60 g/L stannous sulfate, 120-160 g/L concentrated sulfuric acid, 8-20 g/L benzenesulfonate, 0.03-0.08 g/L resveratrol, 0.2-0.5 g/L beta-naphthol, 1.0-2.5 g/L gelatin and 4-6 g/L hydroquinone;
Step three, electrolysis, namely adding the electrolyte obtained in the step two into an electrolytic tank, then using a titanium plate as a cathode and a thick tin plate as an anode, and carrying out electrolysis on the titanium plate at the cathode at the anode distance of 50-80 mm, the cathode current density of 60A/m 2~100A/m2 and the tank voltage of 0.04-0.06V and the electrolysis temperature of 20-40 ℃ to obtain cathode tin on the cathode;
Stripping off the cathode tin obtained in the step three, cleaning, heating and melting, covering with NH 4 Cl when the cathode tin is close to melting, slagging off and casting after the NH 4 Cl is volatilized completely to obtain an electrolytic tin ingot, adding stannous sulfide into the electrolytic tin ingot, heating and stirring, removing scum after cooling, and casting to obtain a copper-removed tin ingot;
And fifthly, vacuum distillation, namely placing the copper-removing tin ingot obtained in the fourth step into a graphite crucible of vacuum distillation equipment, then opening a mechanical pump to vacuumize the vacuum distillation equipment, then opening a diffusion pump to vacuumize further, heating and melting the copper-removing tin ingot after reaching the vacuum degree requirement, preserving heat, then carrying out gassing, pouring out molten tin liquid, and cooling to obtain high-purity tin.
The invention obtains a solution of which the main salt is stannous sulfate by water quenching crude tin into tin beads, adding dilute sulfuric acid, heating and dissolving and solid-liquid separation, changes the precipitation potential of lead and tin by adopting a benzenesulfonate-containing electrolyte for electrolysis, further removes lead elements which are impurities with great difficulty, and further removes other impurity elements in the crude tin, and combines copper removal refining and vacuum distillation to further remove the lead, copper elements and other impurity elements, thereby preparing the tin with low alpha ray quantity and high purity.
The invention adds concentrated sulfuric acid into electrolyte to improve the conductivity of the electrolyte, and simultaneously prevents Sn 2+ from being oxidized into Sn 4+, and adds benzene sulfonate to change the precipitation potential of lead and tin, so as to facilitate the electrolytic removal of lead and tin, and adds resveratrol to improve the conductivity and stability of the electrolyte, thereby improving the purity and yield of tin, adding beta-naphthol to improve cathode polarization, ensuring compact crystallization and smooth surface, preventing whisker formation, adding gelatin to improve the polarization effect of metal ions during cathode reduction, and also playing the roles of refining grains and improving the compactness of a coating, adding hydroquinone as an antioxidant to inhibit Sn 2+ dissolved in the electrolyte from being oxidized into Sn 4+, and inhibiting precipitation and precipitation in the electrolyte, thus preventing the reduction of the electrolytic refining efficiency.
In the copper removal refining, NH 4 Cl is used for covering when the molten tin is close to melting, a large amount of bubbles are generated in a molten pool, metal oxide slag inclusion is effectively removed, stannous sulfide is added into an electrolytic tin ingot, then the molten tin is heated, stirred and cooled, and copper is removed by high-efficiency separation.
The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate is characterized in that the concentration of dilute sulfuric acid in the first step is 9mol/L, and the heating and dissolving are carried out in an oil bath at 90-100 ℃ for 24-48 h. The invention ensures thorough dissolution of tin beads by controlling the concentration of dilute sulfuric acid and the temperature and time of heating.
The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate is characterized in that in the first step, a filter press, a polyester cloth bag or a nylon filter bag is adopted for solid-liquid separation, when the filter press is adopted, the filtering pressure is 0.4MPa, the compression pressure is 0.7MPa, the filter cloth material is polypropylene, and the air permeability of the filter cloth is 100cm 3/cm2/min. The invention ensures the full removal of impurities by controlling the solid-liquid separation device.
The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate is characterized in that the benzenesulfonate in the second step is sodium benzenesulfonate and/or calcium benzenesulfonate. The sodium benzenesulfonate and the calcium benzenesulfonate adopted by the invention have strong complexing capability and leveling property, can change the precipitation potential of lead and tin, improve the removal effect of lead and tin, and are preferably sodium benzenesulfonate, and have stronger complexing capability and leveling property and lower price.
The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate is characterized in that the cathode in the third step can be made of stainless steel or graphite, the purity of the crude tin plate is 2N-4N, the crude tin plate is soaked in dilute hydrochloric acid solution before electrolysis, then cleaned and sleeved with a polyester cloth bag. According to the invention, the crude tin plate is soaked in the dilute hydrochloric acid solution to remove impurities on the surface before electrolysis, and the peeled anode mud is prevented from polluting the electrolyte by coating the terylene cloth bag.
The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate is characterized in that the cleaning process in the fourth step comprises the steps of soaking for 2min by adopting HCl with the mass fraction of 5%, and then washing with deionized water. According to the invention, the residual lead in the electrolyte is removed by soaking with HCl, so that the purity of the electrolytic tin ingot is ensured.
The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate is characterized in that bamboo chips are used for scraping surface scum in time in the casting in the fourth step. The invention ensures the purity of the electrolytic tin ingot by scraping the surface scum.
The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate is characterized in that the temperature of heating and stirring in the fourth step is 900 ℃ for 30min, and the temperature is reduced to 230 ℃. Copper is removed by controlling the parameters of heating and stirring and the parameters of cooling.
The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate is characterized in that the vacuum degree requirement in the fifth step is 0.001Pa-10 Pa, the heating and melting temperature is 1000 ℃ to 1600 ℃, and the heat preservation time is 60 min-120 min. The invention prevents oxidation and impurity introduction through vacuum degree, keeps good evaporation rate, controls the parameters through heating, and efficiently separates and removes lead, antimony and silver.
The method for removing metal impurities by electrolytic coupling vacuum distillation of the benzene sulfonate of tin is characterized in that the chemical components of the high-purity tin in the fifth step meet the standard of 5N or 6N high-purity tin, the content of lead element and bismuth element is less than 1ppm, the content of uranium element and thorium element is less than 1ppb, and the high-purity tin meets the requirement of low alpha-ray amount materials.
Compared with the prior art, the invention has the following advantages:
1. According to the invention, the crude tin is water quenched into tin beads, diluted sulfuric acid is added for heating and dissolving, and solid-liquid separation is carried out, so that a solution with main salt of stannous sulfate is obtained, the electrolytic solution containing benzenesulfonate is adopted, the precipitation potential of lead and tin is changed, and further, lead elements with great difficulty are removed, in addition, other impurity elements in the crude tin can be removed, and the lead, copper elements and other impurity elements are further removed by combining copper removal refining and vacuum distillation, so that the tin with low alpha-ray quantity and high purity is prepared, the problem that the radioactive alpha-particle impurity elements in the crude tin are difficult to remove by an electrolytic method is effectively solved, and the high-purity tin is used as the use requirement of solder, so that the quality of a semiconductor chip is greatly improved.
2. The invention adds concentrated sulfuric acid into electrolyte to improve the conductivity of the electrolyte, and simultaneously prevents Sn 2+ from being oxidized into Sn 4+, and adds benzene sulfonate to change the precipitation potential of lead and tin, so as to facilitate the electrolytic removal of lead and tin, and adds resveratrol to improve the conductivity and stability of the electrolyte, thereby improving the purity and yield of tin, adding beta-naphthol to improve cathode polarization, ensuring compact crystallization and smooth surface, preventing whisker formation, adding gelatin to improve the polarization effect of metal ions during cathode reduction, and also playing the roles of refining grains and improving the compactness of a coating, adding hydroquinone as an antioxidant to inhibit Sn 2+ dissolved in the electrolyte from being oxidized into Sn 4+, and inhibiting precipitation and precipitation in the electrolyte, thus preventing the reduction of the electrolytic refining efficiency.
3. In the copper removal refining, NH 4 Cl is used for covering when the molten tin is close to melting, a large amount of bubbles are generated in a molten pool, metal oxide slag inclusion is effectively removed, stannous sulfide is added into an electrolytic tin ingot, then the molten tin is heated, stirred and cooled, and copper is removed by high-efficiency separation.
4. The method solves the problem that the prior high-purity tin preparation technology is difficult to lead the content of Pb and Bi to be less than 1ppm, and can meet the quality requirement of semiconductor tin solder.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is a flow chart of the process of the invention for removing metallic impurities by electrolytic coupling vacuum distillation of tin benzene sulfonate.
Detailed Description
Fig. 1 is a process flow chart of the invention for removing metal impurities by the electrolytic coupling vacuum distillation of the benzene sulfonate of tin, and as can be seen from fig. 1, the invention firstly heats and melts crude tin and extracts the water to obtain tin beads, then adds the tin beads into dilute sulfuric acid solution, heats and dissolves the tin beads, then carries out solid-liquid separation to obtain stannous sulfate solution, carries out electrolysis on the stannous sulfate solution to obtain cathode tin, adds the cathode tin into stannous sulfide to remove copper and refine the cathode tin, obtains copper and tin ingot, and carries out vacuum distillation on the copper and tin to obtain high-purity tin.
Example 1
The embodiment comprises the following steps:
Firstly, liquid is produced, namely 2N crude tin is placed in a crucible, heated and melted in a muffle furnace, water extraction is carried out to obtain tin beads, then 23g of tin beads are added into 25mL of 9mol/L dilute sulfuric acid solution, heated and dissolved in 90 ℃ oil bath for 36 hours until tin is not dissolved, the solution is poured out, 50mL of deionized water is used for heating together with residues, the rest stannous sulfate is extracted, finally, after the two solutions are combined, a filter press is adopted to filter the solution at a filtering pressure of 0.4MPa and a compression pressure of 0.7MPa, the material of filter cloth is polypropylene, and the air permeability of the filter cloth is 100cm 3/cm2/min, solid-liquid separation is carried out to obtain stannous sulfate solution;
Step two, preparing electrolyte:
Adding concentrated sulfuric acid, sodium benzenesulfonate, resveratrol, naphthol, gelatin, hydroquinone and deionized water into the stannous sulfate solution obtained in the step one to obtain 1000mL of electrolyte, wherein the electrolyte comprises 40g/L stannous sulfate, 120g/L concentrated sulfuric acid, 8g/L sodium benzenesulfonate, 0.03g/L resveratrol, 0.2g/L beta-naphthol, 1.0g/L gelatin and 4g/L hydroquinone;
Step three, electrolysis, namely adding the electrolyte obtained in the step two into an electrolytic tank, taking a titanium plate as a cathode, soaking a crude tin plate with the purity of 2N in a dilute hydrochloric acid solution, cleaning, sleeving a polyester cloth bag as an anode, and carrying out electrolysis on the titanium plate at the cathode current density of 60A/m 2, the tank voltage of 0.04V and the electrolysis temperature of 20 ℃ at the polar distance of 50mm to obtain cathode tin on the cathode;
Stripping cathode tin obtained in the step three, soaking for 2min by adopting HCl with the mass fraction of 5%, washing with deionized water, heating and melting, covering with NH 4 Cl when the cathode tin is nearly melted, slagging off and casting after the NH 4 Cl is completely volatilized, scraping surface scum with bamboo chips in time in the casting process to obtain 30g electrolytic tin ingots, adding stannous sulfide into the electrolytic tin ingots according to the stoichiometric ratio of 1:2 of copper to stannous sulfide in the electrolytic tin ingots, heating and stirring for 30min to 900 ℃, removing scum and casting after the temperature is reduced to 230 ℃, and scraping the surface scum with bamboo chips in time in the casting process to obtain the decoppered tin ingots;
Fifth, vacuum distillation:
Placing the copper-removing tin ingot obtained in the step four into a graphite crucible of vacuum distillation equipment, then opening a mechanical pump to vacuumize the vacuum distillation equipment to 15Pa, then opening a diffusion pump to vacuumize the vacuum degree to 0.01Pa, heating the copper-removing tin ingot to 1150 ℃ to melt and preserve heat for 100min, then deflating, pouring out molten tin liquid, and cooling to obtain high-purity tin.
The high purity tin prepared in this example was subjected to Glow Discharge Mass Spectrometry (GDMS) and the results are shown in table 1 in ppm, wherein 4NSn (99.99) represents a tin sample having a purity of 4N, 5NSn (99.999) represents a tin sample having a purity of 5N, and 6NSn (99.9999) represents a tin sample having a purity of 6N.
TABLE 1
As can be seen from table 1, the chemical components of the high-purity tin prepared by the electrolytic refining coupling vacuum distillation technology in this embodiment all meet the standard of 5N high-purity tin, the content of lead and bismuth is less than 1ppm, the content of uranium and thorium is less than 1ppb, which indicates that the prepared high-purity tin meets the requirement of low alpha-ray amount materials.
The benzenesulfonate salt in this embodiment may also be calcium benzenesulfonate, or sodium benzenesulfonate and calcium benzenesulfonate.
The cathode in this embodiment may also be made of stainless steel or graphite.
Example 2
The embodiment comprises the following steps:
Firstly, liquid is produced, namely 3N crude tin is placed in a crucible, heated and melted in a muffle furnace, water extraction is carried out to obtain tin beads, then 28g of tin beads are added into 30mL of 9mol/L dilute sulfuric acid solution, heating and dissolving are carried out in an oil bath at 100 ℃ for 24 hours until tin is not dissolved any more, the solution is poured out, 50mL of deionized water is used for heating together with residues, residual stannous sulfate is extracted, and finally, solid-liquid separation is carried out on the two parts of solutions by adopting a polyester cloth bag after the two parts of solutions are combined, so as to obtain stannous sulfate solution;
Step two, preparing electrolyte:
Adding concentrated sulfuric acid, sodium benzenesulfonate, resveratrol, naphthol, gelatin, hydroquinone and deionized water into the stannous sulfate solution obtained in the step one to obtain 1000mL of electrolyte, wherein the electrolyte comprises 50g/L stannous sulfate, 140g/L concentrated sulfuric acid, 14g/L sodium benzenesulfonate, 0.05g/L resveratrol, 0.35g/L beta-naphthol, 1.7g/L gelatin and 5g/L hydroquinone;
Step three, electrolysis, namely adding the electrolyte obtained in the step two into an electrolytic tank, taking a titanium plate as a cathode, soaking a crude tin plate with the purity of 3N in a dilute hydrochloric acid solution, cleaning, sleeving a polyester cloth bag as an anode, and carrying out electrolysis on the titanium plate at the cathode current density of 80A/m 2, the tank voltage of 0.05V and the electrolysis temperature of 25 ℃ at the anode distance of 60mm to obtain cathode tin;
Stripping cathode tin obtained in the step three, soaking for 2min by adopting HCl with the mass fraction of 5%, washing with deionized water, heating and melting, covering with NH 4 Cl when the cathode tin is nearly melted, slagging off and casting after the NH 4 Cl is completely volatilized, scraping surface scum with bamboo chips in time in the casting process to obtain 30g electrolytic tin ingots, adding stannous sulfide into the electrolytic tin ingots according to the stoichiometric ratio of 1:2 of copper to stannous sulfide in the electrolytic tin ingots, heating and stirring for 30min to 900 ℃, removing scum and casting after the temperature is reduced to 230 ℃, and scraping the surface scum with bamboo chips in time in the casting process to obtain the decoppered tin ingots;
Fifth, vacuum distillation:
Placing the copper-removing tin ingot obtained in the step four into a graphite crucible of vacuum distillation equipment, then opening a mechanical pump to vacuumize the vacuum distillation equipment to 15Pa, then opening a diffusion pump to vacuumize the vacuum degree to 0.67Pa, heating the copper-removing tin ingot to 1200 ℃ to melt and keep the temperature for 70min, then deflating, pouring out molten tin liquid, and cooling to obtain high-purity tin.
The high purity tin prepared in this example was subjected to Glow Discharge Mass Spectrometry (GDMS) and the results are shown in table 2 in ppm, wherein 4NSn (99.99) represents a tin sample having a purity of 4N, 5NSn (99.999) represents a tin sample having a purity of 5N, and 6NSn (99.9999) represents a tin sample having a purity of 6N.
TABLE 2
As can be seen from table 2, the chemical components of the high-purity tin prepared by the electrolytic refining coupling vacuum distillation technology in this embodiment all meet the standard of 5N high-purity tin, the content of lead and bismuth is less than 1ppm, the content of uranium and thorium is less than 1ppb, which indicates that the prepared high-purity tin meets the requirement of low alpha-ray amount materials.
Example 3
The embodiment comprises the following steps:
Firstly, liquid making, namely placing 4N crude tin in a crucible, heating and melting in a muffle furnace, extracting with water to obtain tin beads, adding 33g of tin beads into 36mL of 9mol/L dilute sulfuric acid solution, heating and dissolving in an oil bath at 90 ℃ for 48 hours until tin is not dissolved, pouring out the solution, heating with 50mL of deionized water and residues to extract residual stannous sulfate, and finally combining the two parts of solutions, and then carrying out solid-liquid separation by adopting a nylon filter bag to obtain stannous sulfate solution;
Step two, preparing electrolyte:
Adding concentrated sulfuric acid, sodium benzenesulfonate, resveratrol, naphthol, gelatin, hydroquinone and deionized water into the stannous sulfate solution obtained in the step one to obtain 1000mL of electrolyte, wherein the electrolyte comprises the following components of 60g/L stannous sulfate, 160g/L concentrated sulfuric acid, 20g/L sodium benzenesulfonate, 0.08g/L resveratrol, 0.5g/L beta-naphthol, 2.5g/L gelatin and 6g/L hydroquinone;
Step three, electrolysis, namely adding the electrolyte obtained in the step two into an electrolytic tank, taking a titanium plate as a cathode, soaking a crude tin plate with the purity of 4N in a dilute hydrochloric acid solution, cleaning, sleeving a polyester cloth bag as an anode, and carrying out electrolysis on the titanium plate at the electrolysis temperature of 40 ℃ under the conditions that the electrode distance is 80mm, the cathode current density is 100A/m 2, the tank voltage is 0.06V, and the cathode tin is obtained on the cathode;
Stripping cathode tin obtained in the step three, soaking for 2min by adopting HCl with the mass fraction of 5%, washing with deionized water, heating and melting, covering with NH 4 Cl when the cathode tin is nearly melted, slagging off and casting after the NH 4 Cl is completely volatilized, scraping surface scum with bamboo chips in time in the casting process to obtain 30g electrolytic tin ingots, adding stannous sulfide into the electrolytic tin ingots according to the stoichiometric ratio of 1:2 of copper to stannous sulfide in the electrolytic tin ingots, heating and stirring for 30min to 900 ℃, removing scum and casting after the temperature is reduced to 230 ℃, and scraping the surface scum with bamboo chips in time in the casting process to obtain the decoppered tin ingots;
Fifth, vacuum distillation:
Placing the copper-removing tin ingot obtained in the step four into a graphite crucible of vacuum distillation equipment, then opening a mechanical pump to vacuumize the vacuum distillation equipment to 15Pa, then opening a diffusion pump to vacuumize the vacuum degree to 0.5Pa, heating the copper-removing tin ingot to 1300 ℃ to melt and keep the temperature for 60min, then deflating, pouring out molten tin liquid, and cooling to obtain high-purity tin.
The high purity tin prepared in this example was subjected to Glow Discharge Mass Spectrometry (GDMS) and the results are shown in table 3 in ppm, wherein 4NSn (99.99) represents a tin sample having a purity of 4N, 5NSn (99.999) represents a tin sample having a purity of 5N, and 6NSn (99.9999) represents a tin sample having a purity of 6N.
TABLE 3 Table 3
As can be seen from table 3, the lead content in the high-purity tin prepared by the electrorefining coupling vacuum distillation technology in this embodiment does not meet the standard of 6N high-purity tin, but meets the standard of 5N high-purity tin, other chemical components meet the standard of 6N high-purity tin, the lead content and the bismuth content are both less than 1ppm, and the uranium content and the thorium content are both less than 1ppb, which indicates that the prepared tin meets the requirement of low alpha-ray amount material.
Example 4
The embodiment comprises the following steps:
Firstly, liquid is produced, namely 4N crude tin is placed in a crucible, heated and melted in a muffle furnace, water extraction is carried out to obtain tin beads, 33g of tin beads are added into 36mL of 9mol/L dilute sulfuric acid solution, heating and dissolving are carried out in 95 ℃ oil bath for 36 hours until tin is not dissolved, 50mL of deionized water is used for pouring out the solution, heating is carried out with residues, residual stannous sulfate is extracted, finally, a filter press is adopted for filtering the two parts of solution after the two parts of solution are combined, the compression pressure is 0.4MPa, the compression pressure is 0.7MPa, the filter cloth material is polypropylene, and the air permeability of the filter cloth is 100cm 3/cm2/min, so as to obtain stannous sulfate solution;
Step two, preparing electrolyte:
adding concentrated sulfuric acid, sodium benzenesulfonate, resveratrol, naphthol, gelatin, hydroquinone and deionized water into the stannous sulfate solution obtained in the step one to obtain 1000mL of electrolyte, wherein the electrolyte comprises 60g/L stannous sulfate, 160g/L concentrated sulfuric acid, 40g/L sodium benzenesulfonate, 0.1g/L resveratrol, 0.8g/L beta-naphthol, 3.2g/L gelatin and 6g/L hydroquinone;
Step three, electrolysis, namely adding the electrolyte obtained in the step two into an electrolytic tank, taking a titanium plate as a cathode, soaking a crude tin plate with the purity of 4N in a dilute hydrochloric acid solution, cleaning, sleeving a polyester cloth bag as an anode, and carrying out electrolysis on the titanium plate at the cathode current density of 100A/m 2, the tank voltage of 0.06V and the electrolysis temperature of 35 ℃ at the polar distance of 80mm to obtain cathode tin on the cathode;
Stripping cathode tin obtained in the step three, soaking for 2min by adopting HCl with the mass fraction of 5%, washing with deionized water, heating and melting, covering with NH 4 Cl when the cathode tin is nearly melted, slagging off and casting after the NH 4 Cl is completely volatilized, scraping surface scum with bamboo chips in time in the casting process to obtain 30g electrolytic tin ingots, adding stannous sulfide into the electrolytic tin ingots according to the stoichiometric ratio of 1:2 of copper to stannous sulfide in the electrolytic tin ingots, heating and stirring for 30min to 900 ℃, removing scum and casting after the temperature is reduced to 230 ℃, and scraping the surface scum with bamboo chips in time in the casting process to obtain the decoppered tin ingots;
Fifth, vacuum distillation:
Placing the copper-removing tin ingot obtained in the step four into a graphite crucible of vacuum distillation equipment, then opening a mechanical pump to vacuumize the vacuum distillation equipment to 15Pa, then opening a diffusion pump to vacuumize the vacuum degree to 0.1Pa, heating the copper-removing tin ingot to 1300 ℃ to melt and keep the temperature for 60min, then deflating, pouring out molten tin liquid, and cooling to obtain high-purity tin.
The high purity tin prepared in this example was subjected to Glow Discharge Mass Spectrometry (GDMS) and the results are shown in table 4 in ppm, wherein 4NSn (99.99) represents a tin sample having a purity of 4N, 5NSn (99.999) represents a tin sample having a purity of 5N, and 6NSn (99.9999) represents a tin sample having a purity of 6N.
TABLE 4 Table 4
As can be seen from table 4, the chemical components of the high-purity tin prepared by the electrolytic refining coupling vacuum distillation technology in this embodiment all meet the standard of 6N high-purity tin, the content of lead and bismuth is less than 1ppm, the content of uranium and thorium is less than 1ppb, which indicates that the prepared high-purity tin meets the requirement of low alpha-ray amount materials.
Example 5
The difference between this example and example 4 is that the mechanical pump was turned on to vacuum the vacuum distillation apparatus to 10Pa, then the diffusion pump was turned on to further vacuum, and after the vacuum degree reached 0.001Pa, the copper-removed tin ingot was heated to 1000 ℃ to melt and heat was preserved for 120min.
Example 6
The difference between the embodiment and the embodiment 4 is that a mechanical pump is started to vacuumize the vacuum distillation equipment to 15Pa, then a diffusion pump is started to vacuumize further, and after the vacuum degree reaches 10Pa, the copper-removing tin ingot is heated to 1600 ℃ to be melted and kept for 60min.
The above description is only of the preferred embodiments of the present invention, and is not intended to limit the present invention. Any simple modification, variation and equivalent variation of the above embodiments according to the technical substance of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (10)
1. A method for removing metallic impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate, comprising the steps of:
Heating and melting 2N-4N crude tin, extracting with water to obtain tin beads, adding the tin beads into a dilute sulfuric acid solution, heating and dissolving, and finally performing solid-liquid separation to obtain a stannous sulfate solution;
Preparing an electrolyte, namely adding concentrated sulfuric acid, benzenesulfonate, resveratrol, naphthol, gelatin, hydroquinone and deionized water into the stannous sulfate solution obtained in the step one to obtain the electrolyte, wherein the electrolyte comprises 40-60 g/L stannous sulfate, 120-160 g/L concentrated sulfuric acid, 8-20 g/L benzenesulfonate, 0.03-0.08 g/L resveratrol, 0.2-0.5 g/L beta-naphthol, 1.0-2.5 g/L gelatin and 4-6 g/L hydroquinone;
Step three, electrolysis, namely adding the electrolyte obtained in the step two into an electrolytic tank, then using a titanium plate as a cathode and a thick tin plate as an anode, and carrying out electrolysis on the titanium plate at the cathode at the anode distance of 50-80 mm, the cathode current density of 60A/m 2~100A/m2 and the tank voltage of 0.04-0.06V and the electrolysis temperature of 20-40 ℃ to obtain cathode tin on the cathode;
Stripping off the cathode tin obtained in the step three, cleaning, heating and melting, covering with NH 4 Cl when the cathode tin is close to melting, slagging off and casting after the NH 4 Cl is volatilized completely to obtain an electrolytic tin ingot, adding stannous sulfide into the electrolytic tin ingot, heating and stirring, removing scum after cooling, and casting to obtain a copper-removed tin ingot;
And fifthly, vacuum distillation, namely placing the copper-removing tin ingot obtained in the fourth step into a graphite crucible of vacuum distillation equipment, then opening a mechanical pump to vacuumize the vacuum distillation equipment, then opening a diffusion pump to vacuumize further, heating and melting the copper-removing tin ingot after reaching the vacuum degree requirement, preserving heat, then carrying out gassing, pouring out molten tin liquid, and cooling to obtain high-purity tin.
2. The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate according to claim 1, wherein in the first step, the concentration of the dilute sulfuric acid is 9mol/L, and the heating and dissolving are carried out in an oil bath at 90-100 ℃ for 24-48 h.
3. The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate according to claim 1, wherein in the step one, a filter press, a polyester cloth bag or a nylon filter bag is adopted for solid-liquid separation, when the filter press is adopted, the filtering pressure is 0.4MPa, the compression pressure is 0.7MPa, the filter cloth material is polypropylene, and the air permeability of the filter cloth is 100cm 3/cm2/min.
4. The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate as claimed in claim 1, wherein in the second step, the benzenesulfonate is sodium benzenesulfonate and/or calcium benzenesulfonate.
5. The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate according to claim 1, wherein the cathode in the third step is made of stainless steel or graphite, the purity of the crude tin plate is 2-4N, the crude tin plate is soaked in dilute hydrochloric acid solution before electrolysis, then washed and sleeved with a dacron cloth bag.
6. The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate as claimed in claim 1, wherein in step four, the cleaning process is that HCl with mass fraction of 5% is used for soaking for 2min, and then deionized water is used for cleaning.
7. The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate as claimed in claim 1, wherein in said casting step four, said surface dross is scraped off by bamboo chips in time.
8. The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate as claimed in claim 1, wherein in step four, the temperature of heating and stirring is 900 ℃ for 30min, and the temperature is reduced to 230 ℃.
9. The method for removing metal impurities by electrolytic coupling vacuum distillation of tin benzenesulfonate according to claim 1, wherein the vacuum degree requirement in the fifth step is 0.001 Pa-10 Pa, the heating and melting temperature is 1000 ℃ to 1600 ℃, and the heat preservation time is 60 min-120 min.
10. The method for removing metal impurities by electrolytic coupling vacuum distillation of benzene sulfonate of tin according to claim 1, wherein the chemical composition of the high-purity tin in the fifth step meets the standard of 5N or 6N high-purity tin, the content of lead element and bismuth element is less than 1ppm, the content of uranium element and thorium element is less than 1ppb, and the high-purity tin meets the requirement of low alpha-ray amount materials.
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