Method for recovering tin from MOCA wastewater and waste

Abstract

The invention discloses a method for recovering tin from MOCA waste water and waste materials, which comprises the steps of pretreating the tin-containing MOCA waste water, pretreating the tin-containing MOCA waste materials, preparing a tin-containing hydrochloric acid solution, preparing crude tin oxide and the like, and is characterized in that the MOCA waste water and waste materials are pretreated, and then hydrochloric acid is used for separating tin elements in MOCA production waste water and the MOCA production waste materials to obtain the tin-containing hydrochloric acid solution; the crude tin oxide prepared by the method has high tin content and few impurities and can be directly applied to a tin smelting raw material or a tin chemical production raw material, the sodium chloride solution is directly recovered by evaporative crystallization, and the MOCA waste after tin separation can also be returned to an MOCA production line, so that the production cost is reduced, and the production efficiency is improved. Therefore, the utilization rate of the metal tin and the MOCA raw material is effectively increased, generation of hazardous waste is reduced, and good economic and environmental benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of metal recovery, in particular to a method for recovering tin from MOCA wastewater and waste materials. Background Art

[0002] The product name of MOCA is 3,3'-dichloro-4,4'-diaminodiphenylmethane, commonly known as Moca, which belongs to the diamine chain extender. When MOCA is used as a vulcanizing agent for cast polyurethane wear-resistant rubber, it can be widely used in the machinery industry, automobile and aircraft manufacturing, mining industry, sports facilities (such as plastic tracks, plastic floors) and light manufacturing industry. It can also be used as a cross-linking agent for polyurethane coatings and adhesives, and a curing agent for epoxy resins to prepare products with extremely high electrical resistance.

[0003] The preparation method of commercial finished product MOCA often uses o-chloroaniline as raw material, first reacts with hydrochloric acid to form o-chloroaniline hydrochloride, then condenses with formaldehyde in the presence of stannous chloride as a catalyst to form 4,4'-methanedi(2-chloroaniline) hydrochloride, then neutralizes with sodium hydroxide to form MOCA, and then adopts multi-stage cleaning, oil-water separation, stripping deamination, dehydration, and granulation to obtain it. The synthetic catalyst stannous chloride not only remains in the synthetic mother liquor but also in the wastewater of the cleaning process and the by-product MOCA waste. The wastewater is evaporated and concentrated, and the recovered distilled water is discharged after meeting the standards, while the catalyst stannous chloride continues to be mixed in the distillation residue and MOCA waste and is safely landfilled as hazardous waste.

[0004] This treatment method is a huge waste of precious metallic tin resources. How to separate and recycle metallic tin from MOCA waste is a bottleneck problem that needs to be solved urgently in this industry. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for recovering tin from MOCA wastewater and waste materials, comprising:

[0006] Pretreatment of tin-containing MOCA wastewater: adding 40-60 wt% hydrogen peroxide to MOCA production process wastewater, stirring until all the residual stannous substance in the MOCA production process wastewater is converted into tetravalent tin, then adding sodium hydroxide to adjust the pH to 6-7, filtering and recovering the tin mud;

[0007] Pretreatment of tin-containing MOCA waste: mixing waste materials (such as MOCA, stannous chloride, tin oxychloride, and dichloroaniline) generated in the MOCA production process with tin mud, adding 25-35wt% hydrochloric acid solution to adjust the pH to 3-5 to obtain a mixture a, adding 3-5L of deionized water to each 1kg of the mixture a, mixing and stirring into a slurry, separating the solid and the liquid, and repeatedly washing 2-5 times to remove soluble salts (such as sodium chloride, etc.) in the tin-containing waste to obtain pretreated tin-containing MOCA waste;

[0008] Preparation of tin-containing hydrochloric acid solution: Detect the tin content in the pretreated tin-containing MOCA waste, add 25-35wt% hydrochloric acid solution to the pretreated tin-containing MOCA waste according to the stoichiometric ratio of tin to hydrogen chloride (1:4-8) mol, heat to react for 4-6 hours, cool, separate the solid and liquid to obtain a tin-containing hydrochloric acid solution, and return the MOCA waste after tin recovery to the MOCA production line for use;

[0009] Preparation of crude tin oxide: Add sodium hydroxide or sodium carbonate to the tin-containing hydrochloric acid solution, adjust the pH value to 6-7, stir, separate the solid and liquid, and wash to obtain crude tin hydroxide and sodium chloride solution.

[0010] Preferably, in the process of pretreating tin-containing MOCA wastewater, the mass concentration of hydrogen peroxide is 50wt%.

[0011] Preferably, in the process of pretreating tin-containing MOCA wastewater, the ratio of MOCA production process wastewater to 40-60wt% hydrogen peroxide is 1000L:(1-5)L. Excessive hydrogen peroxide will lead to excessively high cost of treating wastewater on the one hand, and on the other hand, excessive hydrogen peroxide will also cause secondary environmental pollution.

[0012] Preferably, in the process of pretreating tin-containing MOCA wastewater, the ratio of MOCA production process wastewater to 40-60wt% hydrogen peroxide is 1000L:(2-3)L.

[0013] Preferably, in the process of pretreating tin-containing MOCA wastewater, the stirring time is 2 to 4 hours and the stirring speed is 500 to 1500 r / min.

[0014] Preferably, the heating temperature during the preparation of the tin-containing hydrochloric acid solution is 90-120° C. Reasonable heating temperature can ensure that the hydrochloric acid fully reacts with the tin compounds in the waste material while avoiding unnecessary side reactions or volatilization losses caused by excessively high temperature.

[0015] Preferably, the heating temperature during the preparation of the tin-containing hydrochloric acid solution is 95-110°C.

[0016] Preferably, the mass concentration of the hydrochloric acid solution used in the preparation of the tin-containing hydrochloric acid solution is 31wt%

[0017] Preferably, in the process of preparing crude tin oxide, the stirring time is 2 to 4 hours and the stirring speed is 500 to 700 r / min. The stirring speed should not be too fast, as it will easily generate bubbles and lead to inaccurate pH test. It should not be too slow, as it will lead to uneven stirring and inaccurate pH test. The stirring time should not be too short, as it will lead to incomplete reaction.

[0018] The beneficial effect is that the present application first pre-treats MOCA wastewater and waste materials, then separates the tin element in MOCA production wastewater and MOCA production waste by hydrochloric acid to obtain a tin-containing hydrochloric acid solution, and then neutralizes the tin-containing hydrochloric acid solution by an alkaline substance to form a tin oxide precipitate. The crude tin oxide obtained by this method has a high tin content and less impurities, and can be directly used as a tin smelting raw material or a tin chemical production raw material. The sodium chloride solution is directly recovered by evaporation and crystallization, and the MOCA waste after tin separation can also be returned to the MOCA production line, which effectively improves the utilization rate of metallic tin and MOCA raw materials, reduces the generation of hazardous waste, and has good economic and environmental benefits. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0020] The following embodiments are only used to illustrate the present invention, but are not limited to the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the protection scope of the present invention.

[0021] In the examples of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the examples of the present invention, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art.

[0022] Source of raw materials:

[0023] MOCA wastewater waste was purchased from Huaibei Xingguang New Material Technology Co., Ltd.;

[0024] The remaining reagents are commercially available.

[0025] Example 1

[0026] A method for recovering tin from MOCA wastewater waste, comprising:

[0027] Pretreatment of tin-containing MOCA wastewater: adding 40wt% hydrogen peroxide to MOCA production process wastewater at a volume ratio of 1000L:1L, stirring until all the residual stannous substance in the MOCA production process wastewater is converted into tetravalent tin, the stirring time is 2h, the stirring speed is 500r / min, then adding sodium hydroxide to adjust the pH to 6-7, filtering and recovering the tin mud;

[0028] Pretreatment of tin-containing MOCA waste: mixing the waste generated in the MOCA production process with tin mud, adding 25wt% hydrochloric acid solution to adjust the pH to 5 to obtain a mixture a, adding 3L of deionized water to each 1kg of the mixture a, mixing and stirring into a slurry, separating the solid and the liquid, and repeatedly washing twice to obtain the pretreated tin-containing MOCA waste;

[0029] Preparation of tin-containing hydrochloric acid solution: Detect the tin content in the pretreated tin-containing MOCA waste, add 25wt% hydrochloric acid solution to the pretreated tin-containing MOCA waste according to the stoichiometric ratio of tin to hydrogen chloride of 1mol:4mol, heat to 90℃ for 4h, cool, separate the solid and liquid to obtain the tin-containing hydrochloric acid solution, and return the MOCA waste after tin recovery to the MOCA production line for use;

[0030] Preparation of crude tin oxide: Add sodium hydroxide to the tin-containing hydrochloric acid solution, adjust the pH value to 6-7, stir, then separate the solid and liquid, and wash. The stirring time is 2 hours and the stirring speed is 500r / min to obtain crude tin hydroxide and sodium chloride solution.

[0031] Example 2

[0032] A method for recovering tin from MOCA wastewater waste, comprising:

[0033] Pretreatment of tin-containing MOCA wastewater: adding 50wt% hydrogen peroxide to MOCA production process wastewater at a volume ratio of 1000L:2L, stirring until all the residual stannous substance in the MOCA production process wastewater is converted into tetravalent tin, the stirring time is 3h, the stirring speed is 750r / min, then adding sodium hydroxide to adjust the pH to 6-7, filtering and recovering the tin mud;

[0034] Pretreatment of tin-containing MOCA waste: mixing the waste generated in the MOCA production process with tin mud, adding 28wt% hydrochloric acid solution to adjust the pH to 4 to obtain a mixture a, adding 4L of deionized water to each 1kg of the mixture a, mixing and stirring into a slurry, separating the solid and the liquid, and repeatedly washing 3 times to obtain the pretreated tin-containing MOCA waste;

[0035] Preparation of tin-containing hydrochloric acid solution: Detect the tin content in the pretreated tin-containing MOCA waste, add 31wt% hydrochloric acid solution to the pretreated tin-containing MOCA waste according to the stoichiometric ratio of tin to hydrogen chloride of 1mol:6mol, heat to 95℃ for 5h, cool, separate the solid and liquid to obtain the tin-containing hydrochloric acid solution, and return the MOCA waste after tin recovery to the MOCA production line for use;

[0036] Preparation of crude tin oxide: Add sodium hydroxide or sodium carbonate to the tin-containing hydrochloric acid solution, adjust the pH value to 6-7, stir, then separate the solid and liquid, and wash. The stirring time is 3 hours and the stirring speed is 600r / min to obtain crude tin hydroxide and sodium chloride solution.

[0037] Example 3

[0038] A method for recovering tin from MOCA wastewater waste, comprising:

[0039] Pretreatment of tin-containing MOCA wastewater: adding 55wt% hydrogen peroxide to MOCA production process wastewater in a volume ratio of 1000L:3L, stirring until all the residual stannous substance in the MOCA production process wastewater is converted into tetravalent tin, the stirring time is 3.5h, the stirring speed is 1000r / min, then adding sodium hydroxide to adjust the pH to 6-7, filtering and recovering the tin mud;

[0040] Pretreatment of tin-containing MOCA waste: mixing the waste generated in the MOCA production process with tin mud, adding 32wt% hydrochloric acid solution to adjust the pH to 4 to obtain a mixture a, adding 5L of deionized water to each 1kg of the mixture a, mixing and stirring into a slurry, separating the solid and the liquid, and repeatedly washing 4 times to obtain the pretreated tin-containing MOCA waste;

[0041] Preparation of tin-containing hydrochloric acid solution: Detect the tin content in the pretreated tin-containing MOCA waste, add 33wt% hydrochloric acid solution to the pretreated tin-containing MOCA waste according to the stoichiometric ratio of tin to hydrogen chloride of 1mol:7mol, heat to 110°C for reaction for 5h, cool, separate the solid and liquid to obtain the tin-containing hydrochloric acid solution, and return the MOCA waste after tin recovery to the MOCA production line for use;

[0042] Preparation of crude tin oxide: Add sodium hydroxide or sodium carbonate to the tin-containing hydrochloric acid solution, adjust the pH value to 6-7, stir, then separate the solid and liquid, and wash. The stirring time is 3 hours and the stirring speed is 600r / min to obtain crude tin hydroxide and sodium chloride solution.

[0043] Example 4

[0044] A method for recovering tin from MOCA wastewater waste, comprising:

[0045] Pretreatment of tin-containing MOCA wastewater: adding 60wt% hydrogen peroxide to MOCA production process wastewater at a volume ratio of 1000L:5L, stirring until all the residual stannous substance in the MOCA production process wastewater is converted into tetravalent tin, the stirring time is 4h, the stirring speed is 1500r / min, then adding sodium hydroxide to adjust the pH to 6-7, filtering and recovering the tin mud;

[0046] Pretreatment of tin-containing MOCA waste: mixing the waste generated in the MOCA production process with tin mud, adding 35wt% hydrochloric acid solution to adjust the pH to 3 to obtain a mixture a, adding 5L of deionized water to each 1kg of the mixture a, mixing and stirring into a slurry, separating the solid and the liquid, and repeatedly washing 5 times to obtain the pretreated tin-containing MOCA waste;

[0047] Preparation of tin-containing hydrochloric acid solution: Detect the tin content in the pretreated tin-containing MOCA waste, add 35wt% hydrochloric acid solution to the pretreated tin-containing MOCA waste according to the stoichiometric ratio of tin to hydrogen chloride of 1mol:8mol, heat to 120℃ for 6h, cool, separate the solid and liquid to obtain the tin-containing hydrochloric acid solution, and return the MOCA waste after tin recovery to the MOCA production line for use;

[0048] Preparation of crude tin oxide: Add sodium hydroxide or sodium carbonate to the tin-containing hydrochloric acid solution, adjust the pH value to 6-7, stir, then separate the solid and liquid, and wash. The stirring time is 4 hours and the stirring speed is 700r / min to obtain crude tin hydroxide and sodium chloride solution.

[0049] Test method:

[0050] Crude tin hydroxide was tested according to the Chinese national standard GB / T 24268-2009;

[0051] The test results are shown in Table 1. Table 1 is the test results of the tin content in the crude tin hydroxide.

[0052] Table 1 Detection results of tin content in crude tin hydroxide

[0053]

[0054]

[0055] From the above table data, it can be seen that the tin content in the final product crude tin hydroxide reaches more than 30%, and the tin conversion rate is high, which means that the adoption of this technical solution can effectively remove impurities, and the obtained crude tin oxide has a high tin content and less impurities. The final product crude tin hydroxide can be directly used as tin smelting raw materials or tin chemical production raw materials.

[0056] The above is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for recovering tin from MOCA wastewater and waste materials, characterized in that: include: Pretreatment of tin-containing MOCA wastewater: adding 40-60 wt% hydrogen peroxide to MOCA production process wastewater, stirring until all the residual stannous acid in the MOCA production process wastewater is converted into tetravalent tin, then adding sodium hydroxide to adjust the pH to 6-7, filtering and recovering the tin sludge; Pretreatment of tin-containing MOCA waste: mixing the waste generated in the MOCA production process with the tin mud, adding 25-35wt% hydrochloric acid solution to adjust the pH to 3-5 to obtain a mixture a, adding 3-5L of deionized water to each 1kg of the mixture a, mixing and stirring into a slurry, separating the solid and the liquid, and repeatedly washing 2-5 times to obtain the pretreated tin-containing MOCA waste; Preparation of tin-containing hydrochloric acid solution: Detect the tin content in the pretreated tin-containing MOCA waste, add 25-35wt% hydrochloric acid solution to the pretreated tin-containing MOCA waste according to the stoichiometric ratio of tin to hydrogen chloride (1:4-8) mol, heat to react for 4-6 hours, cool, separate the solid and liquid to obtain the tin-containing hydrochloric acid solution, and return the MOCA waste after tin recovery to the MOCA production line for use; Preparation of crude tin oxide: adding sodium hydroxide or sodium carbonate to the tin-containing hydrochloric acid solution, adjusting the pH value to 6-7, stirring, then solid-liquid separation and washing to obtain crude tin hydroxide and sodium chloride solution.

2. The method for recovering tin from MOCA wastewater and waste materials according to claim 1, characterized in that: In the process of pretreating the tin-containing MOCA wastewater, the mass concentration of the hydrogen peroxide is 50wt%.

3. The method for recovering tin from MOCA wastewater and waste materials according to claim 1, characterized in that: In the process of pretreating the tin-containing MOCA wastewater, the ratio of the MOCA production process wastewater to the 40-60wt% hydrogen peroxide is 1000L:(1-5)L.

4. The method for recovering tin from MOCA wastewater and waste materials according to claim 1, characterized in that: In the process of pre-treating the tin-containing MOCA wastewater, the ratio of the MOCA production process wastewater to the 40-60wt% hydrogen peroxide is 1000L:(2-3)L.

5. The method for recovering tin from MOCA wastewater and waste materials according to claim 1, characterized in that: In the process of pre-treating the tin-containing MOCA wastewater, the stirring time is 2 to 4 hours and the stirring speed is 500 to 1500 r / min.

6. The method for recovering tin from MOCA wastewater and waste materials according to claim 1, characterized in that: The heating temperature during the preparation of the tin-containing hydrochloric acid solution is 90-120°C.

7. The method for recovering tin from MOCA wastewater and waste materials according to claim 1, characterized in that: The heating temperature during the preparation of the tin-containing hydrochloric acid solution is 95-110°C.

8. The method for recovering tin from MOCA wastewater and waste materials according to claim 1, characterized in that: The mass concentration of the hydrochloric acid solution used in the process of preparing the tin-containing hydrochloric acid solution is 31 wt %.

9. The method for recovering tin from MOCA wastewater and waste materials according to claim 1, characterized in that: In the process of preparing the crude tin oxide, the stirring time is 2 to 4 hours and the stirring speed is 500 to 700 r / min.

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