Treatment method of tin-containing waste liquid

Abstract

The invention discloses a tin-containing waste liquid treatment method which comprises the steps of multiple times of rotational flow electrolysis and filtration until the tin ion concentration is lower than a preset value, and filtrate is recovered and filtered. According to the treatment method of the tin-containing waste liquid, the tin-containing waste liquid is subjected to tin extraction treatment by adopting a rotational flow electrolysis technology, after the tin-containing waste liquid enters a rotational flow electrolysis device, most of tin ions or stannous ions are deposited on a cathode to form metallic tin, the other part of tetravalent tin is hydrolyzed to form tin hydroxide precipitates, the metallic tin can be efficiently recycled, the process is simple, and the cost is low. The method is simple and convenient to operate, avoids the harm of the tin-containing waste liquid to the environment, improves the resource recovery rate, saves the tin-containing waste liquid treatment cost, and improves the economic benefits.

Description

Technical Field

[0001] The invention relates to a nonferrous metal recovery process, in particular to a method for treating tin-containing waste liquid. Background Art

[0002] Tinning is a surface treatment technology widely used in the electronics manufacturing industry. During the tinning process, the solution in the plating tank will gradually be consumed. At the same time, the impurities brought into the plated parts will accumulate, resulting in a decrease in the performance of the plating solution. Therefore, the plating tank needs to be replaced regularly. During the tank replacement process, in order to ensure the purity and effect of the new plating solution, the tank body must be thoroughly cleaned, and this process will produce a large amount of tin-containing waste liquid.

[0003] At present, flat-plate electrode structure electrolysis is usually used to treat tin-containing wastewater. However, since the electrolyte is in a low-speed flow exchange state during the electrolysis process, the convective mass transfer rate in the solution has a limit value. When the tin content in the electrolyte is lower than 1g / L, the cathode is prone to concentration polarization during the tin plating process due to the slow solution flow rate, which reduces the electrolysis efficiency and makes the plated body become loose sand, which cannot be peeled off as a whole. Summary of the invention

[0004] The purpose of the present invention is to propose a method for treating tin-containing waste liquid to solve the problem that the above-mentioned existing flat cathode is prone to concentration polarization due to too slow solution flow rate during tin plating, resulting in the plated body becoming loose sand and unable to be effectively recovered.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for treating tin-containing waste liquid, comprising the following steps:

[0007] S1, inputting the tin-containing waste liquid into a cyclone electrolysis device, and obtaining primary electrolytic metallic tin and a first solution through cyclone electrolysis;

[0008] S2, recovering the electrolytic metal tin in step S1, filtering the first solution for the first time to obtain a second solution, and recovering the first filtration residue;

[0009] S3, inputting the second solution into a cyclone electrolysis device, and obtaining a second electrolytic metal tin and a third solution through cyclone electrolysis;

[0010] S4, recovering the secondary electrolytic metallic tin in step S3, filtering the third solution again to obtain a fourth solution, and recovering the filter residue after the second filtration;

[0011] S5, detecting the tin ion concentration in the fourth solution, and when the tin ion concentration is higher than a predetermined value, repeating steps S3 and S4 until the tin ion concentration is lower than a predetermined value, and then recovering the filtered filtrate.

[0012] In the method for treating the tin-containing waste liquid, in steps S1 and S3, the tin-containing waste liquid / second solution is input from the bottom of the cyclone electrolysis device and flows upward in a spiral manner so that the tin-containing waste liquid / second solution is fully in contact with the anode electrode and then output from the top of the electrolyte.

[0013] In the method for treating the tin-containing waste liquid, the flow rate of the tin-containing waste liquid / second solution cyclone electrolysis is 50 to 100 L / min, and the current density of the cyclone electrolysis is 50 to 150 A / m 2 .

[0014] In the method for treating tin-containing waste liquid, the predetermined value of the tin ion concentration is 5 mg / L.

[0015] The method for treating the tin-containing waste liquid further comprises a pretreatment step, and the pretreatment step comprises: pre-filtering the tin-containing waste liquid.

[0016] In the method for treating the tin-containing waste liquid, the pre-filtration in the pre-treatment step, the first filtration in step S2 and the second filtration in step S3 are all filtered using ceramic filters.

[0017] In the method for treating tin-containing waste liquid, the negative electrode of the cyclone electrolysis device is made of stainless steel or titanium, and the positive electrode of the cyclone electrolysis device is a titanium column with a conductive coating or a lead dioxide column with a conductive coating.

[0018] A technical solution in the present invention can have the following beneficial effects:

[0019] The method for treating tin-containing waste liquid adopts cyclone electrolysis technology to extract tin from tin-containing waste liquid. After the tin-containing waste water enters the cyclone electrolysis device, most of the tin ions or stannous ions are deposited on the cathode to form metallic tin, while the other part of tetravalent tin is hydrolyzed to form tin hydroxide precipitation, so that metallic tin can be efficiently recovered. The process is simple and the operation is convenient, and the harm of tin-containing waste liquid to the environment is avoided, the resource recovery rate is improved, the cost of treating tin-containing waste liquid is saved, and the economic benefit is improved. DETAILED DESCRIPTION

[0020] The technical scheme of the present invention is further illustrated by specific embodiments below. In order to facilitate understanding of the present invention, the present invention is described more comprehensively below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0021] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0023] The present invention provides a method for treating tin-containing waste liquid, comprising the following steps:

[0024] S1, inputting the tin-containing waste liquid into a cyclone electrolysis device, and obtaining primary electrolytic metallic tin and a first solution through cyclone electrolysis;

[0025] S2, recovering the electrolytic metal tin in step S1, filtering the first solution for the first time to obtain a second solution, and recovering the first filtration residue;

[0026] S3, inputting the second solution into a cyclone electrolysis device, and obtaining a second electrolytic metal tin and a third solution through cyclone electrolysis;

[0027] S4, recovering the secondary electrolytic metallic tin in step S3, filtering the third solution again to obtain a fourth solution, and recovering the filter residue after the second filtration;

[0028] S5, detecting the tin ion concentration in the fourth solution, and when the tin ion concentration is higher than a predetermined value, repeating steps S3 and S4 until the tin ion concentration is lower than a predetermined value, and then recovering the filtered filtrate.

[0029] The method for treating tin-containing waste liquid adopts cyclone electrolysis technology to extract tin from tin-containing waste liquid. After the tin-containing waste water enters the cyclone electrolysis device, most of the tin ions or stannous ions are deposited on the cathode to form metallic tin, while the other part of tetravalent tin is hydrolyzed to form tin hydroxide precipitation, so that metallic tin can be efficiently recovered. The process is simple and the operation is convenient, and the harm of tin-containing waste liquid to the environment is avoided, the resource recovery rate is improved, the cost of treating tin-containing waste liquid is saved, and the economic benefit is improved.

[0030] Water undergoes oxidation reaction at the anode to produce oxygen and hydrogen ions (H + ), the ionic equation of the oxidation reaction at the anode is:

[0031] 2H20-4e - =O2+4H + ;

[0032] Tin ions react at the cathode: they gain electrons, are reduced to metallic tin and deposited on the cathode. The ionic equation for the reduction reaction at the cathode is:

[0033] Sn2+ +2e - = Sn;

[0034] Sn 4+ +4e - =Sn.

[0035] Sn 4+ The ions will hydrolyze to produce tin hydroxide precipitate, the ionic formula is:

[0036] Sn 4+ +H20=Sn(OH)4+4H + .

[0037] Specifically, in steps S1 and S3, the tin-containing waste liquid / second solution is input from the bottom of the cyclone electrolysis device and flows upward in a spiral manner so that the tin-containing waste liquid / second solution is fully in contact with the anode electrode and then output from the top of the electrolyte.

[0038] The above-mentioned input method of the tin-containing waste liquid / the second solution can avoid the problem of concentration polarization caused by too slow solution flow rate during cathode tin plating when the tin ion content in the electrolyte is lower than 1g / L, and prevent the plated body from becoming loose sand and being unable to be peeled off as a whole. It improves the electrolysis efficiency and facilitates the recovery of the metallic tin obtained by electrolysis.

[0039] Specifically, the flow rate of the tin-containing waste liquid / second solution cyclone electrolysis is 50-100 L / min, and the current density of the cyclone electrolysis is 50-150 A / m 2 .

[0040] In a specific embodiment of the present invention, the flow rate of the tin-containing waste liquid / the second solution is 50 to 100 L / min, and the current density of the cyclonic electrolysis is 50 to 150 A / m 2 The time that the tin-containing waste liquid / second solution spends in the cyclone electrolysis device can be controlled by the flow rate and flow velocity, thereby controlling the cyclone electrolysis reaction time. The metallic tin can be effectively recovered by the above-mentioned flow rate, flow velocity entering the cyclone electrolysis and current density.

[0041] Specifically, the predetermined value of the tin ion concentration is 5 mg / L.

[0042] When the tin ion concentration is lower than 5 mg / L, it is difficult to recover metallic tin by cyclone electrolysis. The solution after the cyclone electrolysis can be discharged into a comprehensive wastewater pool for further treatment.

[0043] Specifically, the method further comprises a pretreatment step, wherein the pretreatment step comprises: pre-filtering the tin-containing waste liquid.

[0044] Using the above steps, pre-filtration can improve the stability of subsequent processes, especially in the case of chemical reactions or biological processes, where the removal of large particles helps ensure the uniformity and efficiency of the reaction.

[0045] Specifically, the pre-filtration in the pre-treatment step, the first filtration in step S2 and the second filtration in step S3 are all filtered using ceramic filters.

[0046] After electrolysis, the concentration of tin ions in the tin-containing solution will decrease; and after the low-concentration tin-containing solution is treated by cyclone electrolysis, the solution will produce fine tin-containing precipitates, which will be suspended in the solution. General filtering methods cannot completely separate the precipitates. The ceramic filter is a filtering device made of ceramic materials. The ceramic filter is equipped with a ceramic membrane. The ceramic membrane is used to filter the tin-containing precipitate wastewater and effectively filter out Sn. 4+ The tin hydroxide precipitation produced by ion hydrolysis avoids the influence of tin-containing precipitation on the cyclonic electrolysis.

[0047] Specifically, the negative electrode of the cyclone electrolysis device is made of stainless steel or titanium, and the positive electrode of the cyclone electrolysis device is a titanium column with an electric conductive coating or a lead dioxide column with an electric conductive coating.

[0048] Stainless steel or titanium has good conductivity, oxidation resistance and stability, which can improve the durability and safety of the electrode.

[0049] Titanium is an excellent conductive material, and conductive coating can further enhance its conductivity, allowing current to be conducted more efficiently.

[0050] The electrical conductivity of lead dioxide is relatively poor, but its electrical conductivity in electrochemical reactions can be enhanced by improving the conductive coating. Using titanium columns with conductive coatings or lead dioxide columns with conductive coatings as electrodes can improve electrical conductivity, enhance electrochemical reaction rates, and improve stability and wear resistance.

[0051] Example Group A

[0052] A method for treating tin-containing waste liquid comprises the following steps:

[0053] Pretreatment step: inputting the tin-containing waste liquid into a ceramic filter for pre-filtration;

[0054] S1, inputting the tin-containing waste liquid into a cyclone electrolysis device, and obtaining primary electrolytic metallic tin and a first solution through cyclone electrolysis;

[0055] S2, recovering the electrolytic metal tin in step S1, inputting the first solution into a ceramic filter for primary filtration to obtain a second solution, and recovering the primary filtration residue;

[0056] S3, inputting the second solution into a cyclone electrolysis device, and obtaining a second electrolytic metal tin and a third solution through cyclone electrolysis;

[0057] S4, recovering the secondary electrolytic metallic tin in step S3, inputting the third solution into a ceramic filter, filtering it again to obtain a fourth solution, and recovering the filter residue after the second filtration;

[0058] S5. Detect the tin ion concentration in the fourth solution. When the tin ion concentration is higher than 5 mg / L, repeat steps S3 and S4 until the tin ion concentration is lower than 5 mg / L, and then recover the filtered filtrate.

[0059] The initial tin content, tin-containing waste liquid / second solution flow rate, tin-containing waste liquid / second solution flow rate, the number of repetitions of step S3 and step S4, current density and the tin content of the final filtered filtrate in each embodiment are shown in Table 1.

[0060] Table 1-Specific parameters

[0061]

[0062] It can be seen from Examples 1 to 4 that the metallic tin in the tin-containing waste liquid can be effectively recovered by using the cyclone electrolysis technology to extract tin from the tin-containing waste liquid.

[0063] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific embodiments of the present invention without creative work, and these equivalent variations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A method for treating tin-containing waste liquid, characterized in that: The following steps are involved: S1, inputting the tin-containing waste liquid into a cyclone electrolysis device, and obtaining primary electrolytic metallic tin and a first solution through cyclone electrolysis; S2, recovering the electrolytic metal tin in step S1, filtering the first solution for the first time to obtain a second solution, and recovering the first filtration residue; S3, inputting the second solution into a cyclone electrolysis device, and obtaining a second electrolytic metal tin and a third solution through cyclone electrolysis; S4, recovering the secondary electrolytic metallic tin in step S3, filtering the third solution again to obtain a fourth solution, and recovering the filter residue after the second filtration; S5, detecting the tin ion concentration in the fourth solution, and when the tin ion concentration is higher than a predetermined value, repeating steps S3 and S4 until the tin ion concentration is lower than a predetermined value, and then recovering the filtered filtrate.

2. The method for treating tin-containing waste liquid according to claim 1, characterized in that: In the steps S1 and S3, the tin-containing waste liquid / second solution is input from the bottom of the cyclone electrolysis device and flows upward in a spiral manner so that the tin-containing waste liquid / second solution is fully in contact with the anode electrode and then output from the top of the electrolyte.

3. The method for treating tin-containing waste liquid according to claim 2, characterized in that: The flow rate of the tin-containing waste liquid / second solution cyclone electrolysis is 50-100 L / min, and the current density of the cyclone electrolysis is 50-150 A / m 2 .

4. The method for treating tin-containing waste liquid according to claim 1, characterized in that: The predetermined value of the tin ion concentration is 5 mg / L.

5. The method for treating tin-containing waste liquid according to claim 1, characterized in that: The method further comprises a pretreatment step, wherein the pretreatment step comprises: pre-filtering the tin-containing waste liquid.

6. The method for treating tin-containing waste liquid according to claim 5, characterized in that: The pre-filtration in the pre-treatment step, the first filtration in step S2 and the second filtration in step S3 are all filtered using ceramic filters.

7. The method for treating tin-containing waste liquid according to claim 1, characterized in that: The negative electrode of the cyclone electrolysis device is made of stainless steel or titanium, and the positive electrode of the cyclone electrolysis device is a titanium column with a conductive coating or a lead dioxide column with a conductive coating.

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