A method for recovering metallic tin from tin containing wastes formed in the tin plating process

Abstract

The invention relates to a method for recovering tin-containing wastes formed in the tin plating (ETL line) process as metallic tin (5).

Description

[0001] A METHOD FOR RECOVERING METALLIC TIN FROM TIN CONTAINING WASTES FORMED IN THE TIN PLATING PROCESS

[0002] Field of the Invention

[0003] The invention relates to a method for recovering tin-containing wastes formed in the tinplating (ETL line) process as metallic tin.

[0004] Background of the Invention

[0005] Production wastes with high tin content generated in a production facility are generally utilized by selling them to other companies. However, metallic tin cannot be recovered from the said wastes, instead these wastes are sold abroad. In the study of Henao et al., one of the studies carried out in this field, tin recovery was carried out with a two-stage recycling method [1]. In the said method, tin oxide (SnO2), a secondary raw material enriched with tin, is produced by acid leaching after the grinding process. However, it is not possible to obtain metallic tin from tin-containing waste in a single step.

[0006] In the study of Chang et. al., one of the applications known in the state of the art, the method of obtaining metallic tin from industrial tin-bearing byproducts with carbothermic reduction smelting is disclosed [2]. In the said study, the starting raw material, the use of different chemicals and the application of smelting at different temperatures are noteworthy. High process temperature (1200°C) increases energy costs

[0007] United States Patent document no US6110349 A, an application known in the state of the art, discloses recovering tin anode from tin sludge obtained from tinplating baths. The said patent application only covers tin recovery from tin sludge obtained from plating baths. There is no explanation for the use of tin slag with high tin content. However, in the said application, hydrometallurgical methods (aqueous systems) are used and pyrometallurgical methods are not mentioned. Whereas, in the pyrometallurgical method, it is possible to perform the reduction process in a single step by avoiding various intermediate processes.

[0008] United States patent document no US4119136 A, an application known in the state of the art, relates to a process and an apparatus for recovering tin from tin containing dross obtained in electronic industry.

[0009] Japanese Patent document no JPH0297624 A, an application known in the state of the art, relates to a recovery method developed for tinplated scrap steels.

[0010] Chinese Patent document no CN112142098 A, an application known in the state of the art, discloses producing Ag coated nanoparticle SnCh material by using tin sludge.

[0011] United States patent document no US2364815 A, an application known in the state of the art, discloses a method for recovering tin from tin-iron alloys.

[0012] Chinese patent document no CN108330296 A, an application known in the state of the art, discloses a method developed for recovering tin from tinplated wastes. In the said method, a coarse reduction process is applied, starting at a temperature of 900 °C and bringing it to 500-600 °C for 80-90 minutes. The product obtained at the end of this process is an intermediate product, not metallic tin. Afterwards, the said intermediate product is subjected to hydrometallurgical reduction process.

[0013] Japanese patent document no JP11092839, an application known in the state of the art, discloses a method developed for recovering metallic tin from a sludge containing tin oxide.

[0014] Summary of the Invention

[0015] The main objective of the present invention is to recover tin, an expensive metal which is lost in waste. Therefore, it is possible to prevent economic loss. The method of the present invention differs from the methods in the state of the art believed to have similar contents, mainly in terms of the starting raw material, method, type, and purity of the final product obtained.

[0016] Unlike the applications in the state of the art, in the present invention, it is essential to recover metallic tin from the slag obtained from tin plating baths and tin melting furnace. As a result of the chemicals and their compositions used in the method of the present invention, the reduction process can be carried out at 10000C and tin with purity above 95% can be obtained. In this method, a ceramic-based crucible is used.

[0017] Detailed Description of the Invention

[0018] “A Method for Recovering Metallic Tin from Tin Containing Wales Formed in the Tin Plating Process” developed in order to fulfil the objective of the present invention is illustrated in the accompanying figure, in which

[0019] Figure 1 is a schematic representation of a method for recovering metallic tin from tin-containing wastes formed in the tin plating process of the present invention.

[0020] The components shown in the figures are each given reference numbers as follows:

[0021] 100. Method of recovering metallic tin

[0022] 101. Drying process

[0023] 102. Melting process

[0024] 1. Tin sludge

[0025] 2. Tin slag

[0026] 3. Reducing agent

[0027] 4. Slagging agent

[0028] 5. Metallic tin A method (100) for recovering metallic tin from tin containing wasted formed in the tin plating process of the present invention relates to a method for recovering tin containing wastes obtained in tinplating (ETL line) process as metallic tin (5), and comprises the steps of:

[0029] • applying drying process (101) to the tin sludge (1) coming out of the ETL line,

[0030] • mixing the tin slag (2) coming out of the ETL line with tin sludge (1) to which the drying process (101) has been applied, reducing agent (3) and slagging agent (4) components, subjecting it to the melting process (102) and recovering the metallic tin (5).

[0031] The invention relates to a method (100) for recovering tin-containing wastes formed in the tin plating (ETL line) process as metallic tin (5). Two different tin- containing wastes emerge from the ETL line. One of these wastes is tin slag (2) and is obtained from the tin ingot melting furnace. The other waste is tin sludge obtained from the tin plating bath (1). Tin sludge (1) is first subjected to the drying process (101). Then, the melting process (102) is applied to the tin sludge (1) and tin slag (2). Carbon black, Na2COs and SiO2 components are used during melting. While carbon black functions as a reducing agent (3), Na2COa and SiO2 act as a slagging agent (4). While obtaining these chemicals, a number of preliminary experiments were carried out and the results of these were debatably explained in the experimental studies section. Tin sludge (1) and tin slag (2) are mixed with reducing (3) and slagging (4) components and melted preferably at 1000 °C for 2 hours. As a result of the melting process (102), metallic tin (5) with over 99% purity is obtained. More than 95% of the tin found in waste is recovered. In addition, the purity of the tin obtained is such that it can be used again in the ETL line.

[0032] The method of the present invention can also be applied to other raw materials with similar chemical content. However, in this case, optimization of the process parameters will be required. EXPERIMENTAL STUDIES

[0033] The experiments carried out within the scope of the study were designed to obtain tin at the highest purity, and the experiment with the highest tin content was determined as the reference recipe. While determining this recipe, temperature, time and chemical composition were considered as the experimental parameters and experimental sets were created accordingly. Another parameter that is taken into consideration is creating a recipe in which tin slag and sludge can be evaluated together. For this purpose, experiments were carried out in sets in which only one type of waste was used, and then new sets were created in which both types of waste were evaluated. The experimental conditions and the obtained metallic tin purity were given in 3 different tables.

[0034] In tin mud experiments conducted at 900°C, an average of 98% purity of tin was obtained. One of the experimental parameters whose effect is investigated here is the SiO2 effect. Although SiO2 does not have a serious effect on purity, it is necessary to use it in practice as it practically facilitates the separation of metal and slag by creating a glassy phase. Therefore, SiO2 was used in the following experiments. Another parameter that is optimized here is time. Trials were carried out at 4 different times, namely for 1, 2, 3 and 12 hours. As a result, it was concluded that 1 hour was not enough to complete the reaction, however since the purity of the metallic tin obtained from the experiments performed in 2, 3 and 12 hours was very close, the most appropriate time was 2 hours. When the results were evaluated in terms of temperature and composition, it was concluded that the optimum conditions were with the experiment carried out with Na2COs at 1000°C. Unlike the ones given in this list, CaCCh has also been tried as a slagging agent. However, since metallic reduction did not occur, it was not included in the list here. Table 1. Experiments carried out with tin sludge and their results Table 2. Experiments carried out with tin slag and their results

[0035] In the experiment carried out using tin sludge, over 99.5% tin purity was achieved for all experiments in the optimized chemical composition at different temperatures. Here, the carbon amount was tried to be optimized and successful results were obtained in all tried ranges.

[0036] As seen in the table, the purity of the obtained tin metal is more than 97% for all experimental conditions. While metal with over 99% purity can be obtained from tin slag at 900°C, this does not seem possible for tin sludge. For tin sludge, purities above 99% can only be achieved at 1000°C. However, since processing at 1100°C does not show any significant increase in tin purity, not many experiments have been carried out at this temperature. Table 3. Experiments carried out with tin sludge and slag and their results As the last step of the study, an experiment was carried out in which tin sludge and slag were used together. As a result of this experiment, tin with a purity of over 99% was obtained.

[0037] The experimental conditions in which two different tin wastes were used were determined as optimum conditions.

[0038] REFERENCES

[0039] [1]. Henao, H. M., Masuda, C., & Nogita, K. (2015). Metallic tin recovery from wave solder dross. International Journal of Mineral Processing, 137, 98-105.

[0040] [2]. Chang, J., & Sohn, H. (2021). The Recovery of Metallic Tin from an

[0041] Industrial Tin-Bearing By-Product Containing Na2SO4 by Reduction Smelting Process. Metals, 11(11), 1697.

Claims

CLAIMS1. A method for recovering tin-containing wastes formed in the tin plating (ETL line) process as metallic tin (5), characterized in that it comprises the steps of:• applying drying process (101) to the tin sludge (1) coming out of the ETL line,• mixing the tin slag (2) coming out of the ETL line with tin sludge (1) to which the drying process (101) has been applied, reducing agent (3) and slagging agent (4) components, subjecting it to the melting process (102) and recovering the metallic tin (5).

2. A method according to claim 1, characterized in that carbon black is used as reducing agent (3).

3. A method according to claim 1, characterized in that Na2COs and SiCh are used as slagging agent (4).

4. A method according to claim 1, characterized in that melting process (102) is carried out at 1000 °C for 2 hours.

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