Method for comprehensively utilizing and recycling organic silicon waste contact

Abstract

The invention provides a comprehensive utilization and recovery method for organic silicon waste contact mass, which comprises the steps of desilicication, iron removal, cuprous chloride preparation and copper preparation, and specifically comprises the following steps: leaching the organic silicon waste contact mass with hydrochloric acid under an oxidation condition, and carrying out solid-liquid separation to obtain a leaching solution a and a leaching residue b; iron powder is added into the leaching solution a for a replacement reaction, and copper sponge c and a replacement solution d are obtained; adding a sulfuric acid solution into the sponge copper c, leaching under the condition of introducing oxygen, and carrying out solid-liquid separation to obtain a leaching solution e and a leaching residue f; adding copper powder into the leachate e for reaction, and performing solid-liquid separation to obtain cuprous chloride precipitate and purified leachate g; the cuprous chloride precipitate is used as a catalyst for producing methyl chlorosilane; and copper powder or cathode copper and an electrodeposition post-solution are prepared by purifying the leaching solution g through electrodeposition.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling, and in particular relates to a method for comprehensive utilization and recycling of waste organosilicon contacts. Background Art

[0002] Organic silicon materials have excellent properties such as heat resistance, corrosion resistance, easy processing, and low surface tension. They are widely used in aerospace, new materials, biomedicine, electronic appliances and other fields. Methylchlorosilane is the main raw material for synthesizing organic silicon materials. It is industrially prepared in a fluidized bed with silicon powder and methyl chloride as raw materials and copper powder as a catalyst. However, after the fluidized bed has been running for a certain period of time, the reaction performance of silicon powder deteriorates due to the accumulation of carbon on the surface of silicon powder particles and impurity elements in the silicon powder particles. In order to avoid a decrease in yield, this part of silicon powder needs to be discharged from the production system through airflow, and the resulting powder is the waste contact body.

[0003] my country produces about 25,000 tons of waste contacts every year. With the further expansion of domestic silicone production capacity, this number will continue to increase. At present, research on waste contacts mainly focuses on two aspects. One is to reduce the emission of waste contacts from the source, and the other is to recover the valuable elements in the waste contacts. In order to reduce the source of waste contacts, researchers have proposed improvement measures such as setting up air flow nozzles in the fluidized bed and energy mills at the bottom of the reactor to reduce the discharge of waste contacts. Another idea is to put the waste contacts back into the fluidized bed after treatment. Shade removes impurities on the surface of the waste contacts by grinding and returns them to the fluidized bed, reducing the silicon loss rate to 8%.

[0004] The treatment of waste organic silicon contacts mainly includes: (1) recovery of elemental copper by oxidation-reduction method; (2) synthesis of phenyl monomer using silicon powder; (3) recovery of divalent copper salt; (4) synthesis of silicon tetroxide using silicon powder.

[0005] Regarding the recovery of valuable elements in waste contacts, the current research focus is on the recovery and utilization of copper in waste contacts. Waste contacts contain about 5% to 15% copper. In industry, hydrochloric acid leaching is generally used under oxidizing conditions. The copper leaching solution is used to prepare sponge copper using iron powder replacement method. The sponge copper obtained is of low grade and has low economic value for external sale. Summary of the invention

[0006] The purpose of the present invention is to provide a method for comprehensive utilization and recovery of waste organosilicon contacts.

[0007] The object of the present invention is achieved in that the method for recovering copper from waste organic silicon contacts comprises the steps of desiliconization, iron removal, preparation of cuprous chloride, and preparation of copper, specifically comprising: A. Desiliconization: 1) Leaching the waste organosilicon contact with hydrochloric acid under oxidizing conditions, and separating the solid and liquid to obtain a leachate a and a leach residue b; 2) Add iron powder to the leaching solution a to carry out a replacement reaction to obtain sponge copper c and replacement solution d; B. Iron removal: Sulfuric acid solution is added to the sponge copper c to carry out leaching under the condition of oxygen introduction, and the leaching solution e and leaching residue f are obtained after solid-liquid separation; C. Preparation of cuprous chloride: adding copper powder to the leaching solution e for reaction, and performing solid-liquid separation to obtain cuprous chloride precipitate and purified leaching solution g; the cuprous chloride precipitate is used as a catalyst for producing methylchlorosilane; D. Copper preparation: Copper powder or cathode copper and post-electrolysis liquid are prepared by electrolysis of the purified leaching solution g, and the post-electrolysis liquid is returned to step B.

[0008] The specific operations are as follows: (1) Desiliconization: The waste contact is leached with hydrochloric acid under oxidizing conditions, and the obtained leaching solution is replaced with iron to obtain sponge copper; the waste contact is leached with hydrochloric acid under oxidizing conditions, the leaching rate of Cu is greater than 99%, silicon and carbon are almost not leached, the leaching rate of zinc is greater than 99%, and the sponge copper obtained after replacement with iron powder contains more than 65% copper. The contents of other impurities in the sponge copper are 5-8% iron, 2-5% silicon, and 2-8% chlorine; (2) Iron removal: Leach the sponge copper in a high pressure autoclave with dilute sulfuric acid for 1-2 hours, maintain the temperature above 160°C, and filter to obtain the leachate. The sponge copper is leached in a high pressure autoclave, where the copper leaching rate is >99%, the chlorine leaching rate is >98%, and the iron will be converted into hematite (Fe3O4) during the leaching process and remain in the leaching residue, and the iron leaching rate is <5%; (3) Preparation of cuprous chloride: copper powder is added to the leachate to prepare cuprous chloride precipitate, which is filtered to obtain a purified leachate; the purified leachate contains less than 0.3 g of iron, less than 0.2 g of chlorine, and less than 0.5 g of silicon. The obtained cuprous chloride precipitate can be used as a catalyst for the production of methylchlorosilane and returned to the previous process flow for use; (4) Electrolytic production of copper powder or metallic copper; Electrolytic production of purified leaching solution to produce copper powder or cathode copper. The prepared copper powder can also be returned to the previous process flow and used as a catalyst; the prepared cathode copper meets the A-grade cathode copper standard in GBT 467-2010 cathode copper standard.

[0009] The main components of the waste contact body are silicon, copper, carbon, zinc, etc., and their contents in the waste contact body are 65% to 75% silicon, 10% to 15% copper, 1% to 5% carbon, and 0.2% to 0.8% zinc, respectively. The contents of carbon and zinc are low, and have little impact on subsequent treatment, and do not need to be considered.

[0010] In the step (1), the concentration of hydrochloric acid is 50 g / L-200 g / L, the liquid-to-solid ratio is 2:1-7:1 ml / g (the liquid-to-solid ratio is the ratio of liquid to waste contact body), and the leaching time is 1-2 hours.

[0011] The oxidation conditions in step (1) are adding hydrogen peroxide or introducing oxygen, the ratio of hydrogen peroxide: waste contact body is 1:1-1.5:1 ml / g; the oxygen introduction rate is 2-3 L / min.

[0012] In step (2), the concentration of sulfuric acid is 120-180 g / L, and the liquid-to-solid ratio is 5:1-8:1 (the liquid-to-solid ratio is the ratio of liquid to sponge copper).

[0013] The pressure of oxygen introduced into the autoclave in step (2) is 0.2-1.8 MPa.

[0014] In step (3), the amount of copper powder added is 0.5-1 times the chlorine content (measured by mass ratio), and the reaction time is 10-120 minutes.

[0015] The process for preparing copper powder by electrowinning in step (4) is as follows: adjusting the Cu content of the purified leaching solution to 1-20 g / L, the sulfuric acid concentration to 20-60 g / L, and the current density to 1000-3000 mA / m 2 .

[0016] The process for preparing cathode copper by electrowinning in step (4) is as follows: adjusting the Cu content of the purified leaching solution to 40-60 g / L, the sulfuric acid concentration to 150-200 g / L, and the current density to 150-230 mA / m 2 .

[0017] Beneficial effects of the present invention: (1) In the process of recovering copper from waste contacts of the present invention, the effective elements silicon, chlorine and copper with high content in the waste contacts can be recovered and utilized, which is environmentally friendly and has good economic benefits; (2) The cuprous chloride precipitate obtained by the present invention can be used as a catalyst for producing methylchlorosilane and returned to the previous process flow for use; (3) The copper powder obtained by the present invention is returned to the previous process flow and used as a catalyst; the prepared cathode copper meets the Class A cathode copper standard in GBT 467-2010 cathode copper standard and can be sold externally; (4) The copper leaching rate of the leaching process of the present invention is high, the copper loss rate during the purification process is low, and the copper element can form a closed loop in the overall process without outflow, and there is almost no copper loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the embodiments, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0020] The method for recovering copper from waste organic silicon contacts of the present invention comprises the steps of desiliconization, iron removal, preparation of cuprous chloride, and preparation of copper, and specifically comprises: A. Desiliconization: 1) Leaching the waste organosilicon contact with hydrochloric acid under oxidizing conditions, and separating the solid and liquid to obtain a leachate a and a leach residue b; 2) Add iron powder to the leaching solution a to carry out a replacement reaction to obtain sponge copper c and replacement solution d; B. Iron removal: Sulfuric acid solution is added to the sponge copper c to carry out leaching under the condition of oxygen introduction, and the leaching solution e and leaching residue f are obtained after solid-liquid separation; C. Preparation of cuprous chloride: adding copper powder to the leaching solution e for reaction, and performing solid-liquid separation to obtain cuprous chloride precipitate and purified leaching solution g; the cuprous chloride precipitate is used as a catalyst for producing methylchlorosilane; D. Copper preparation: Copper powder or cathode copper and post-electrolysis liquid are prepared by electrolysis of the purified leaching solution g, and the post-electrolysis liquid is returned to step B.

[0021] A. The concentration of hydrochloric acid in step 1) is 50-200 g / L.

[0022] The oxidation conditions described in step A1) are adding hydrogen peroxide or passing oxygen.

[0023] The concentration of the sulfuric acid solution described in step B is 120-180 g / L.

[0024] The pressure of the oxygen introduced in step B is controlled to be 0.2-1.87 MPa.

[0025] The amount of copper powder added in step C is 0.5 to 1.0 times the chlorine content.

[0026] The reaction time in step C is 10 to 120 minutes.

[0027] The copper powder prepared by electrowinning in step D is obtained by adjusting the copper content of the purified leaching solution to 1-20 g / L, the sulfuric acid concentration to 20-60 g / L, and the current density to 1000-3000 mA / m 2 .

[0028] In step D, the cathode copper is prepared by electrowinning by adjusting the copper content of the purified leaching solution to 40-60 g / L, the sulfuric acid concentration to 150-200 g / L, and the current density to 150-230 mA / m 2 .

[0029] The present invention is further described below with specific implementation cases: Example 1 (1) Desiliconization: 50g of waste contact was leached with 120g / L hydrochloric acid for 1h (liquid-to-solid ratio 6:1) under oxygen flow, and 5g of the obtained leaching solution was used for replacement to obtain sponge copper; the leaching rate of Cu was 99.78%, silicon and carbon were almost not leached, the leaching rate was less than 2%, the leaching rate of zinc was 99.27%, and the sponge copper obtained after replacement with iron powder contained 68.77% copper. The contents of other impurities in the sponge copper were 5.26% iron, 3.4% silicon, and 2.3% chlorine; (2) Iron removal: Sponge copper was leached in an autoclave with dilute sulfuric acid at a concentration of 160 g / L for 1 h (liquid-to-solid ratio of 7:1), the oxygen pressure was 0.6 MPa, the temperature was maintained at 165 °C, and the leachate was filtered to obtain the leachate. The sponge copper was leached in an autoclave, and the copper leaching rate was 99.89%, the chlorine leaching rate was 98.45%, and the iron was converted into hematite (Fe3O4) during the leaching process and remained in the leaching residue. The iron leaching rate was <5%. The leachate contained Cu 78 g / L, Fe 0.46 g / L, and Si 0.56 g / L. (3) Preparation of cuprous chloride: copper powder is added to the leachate to prepare cuprous chloride precipitate, which is filtered to obtain a purified leachate; the purified leachate contains less than 0.3 g of iron, less than 0.2 g of chlorine, and less than 0.5 g of silicon. The obtained cuprous chloride precipitate can be used as a catalyst for the production of methylchlorosilane and returned to the previous process flow for use; (4) Electrolytic preparation of copper powder; adjust the Cu content of the purified leaching solution to 1-20 g / L, the sulfuric acid concentration to 20-60 g / L, and the current density to 1000-3000 mA / m 2 , copper powder was obtained on the cathode, and the grade of copper powder was 99.996%.

[0030] Example 2 (1) Desiliconization: 50g of waste contact was leached with 80g / L hydrochloric acid for 1.4h (liquid-to-solid ratio 6:1) under oxygen flow, and 5g of the obtained leaching solution was used for replacement to obtain sponge copper; the leaching rate of Cu was 99.24%, silicon and carbon were almost not leached, the leaching rate was less than 2%, the leaching rate of zinc was 99.67%, and the sponge copper obtained after replacement with iron powder contained 71.33% copper. The contents of other impurities in the sponge copper were 4.24% iron, 3.1% silicon, and 3.1% chlorine; (2) Iron removal: Sponge copper was leached in an autoclave with dilute sulfuric acid at a concentration of 157 g / L for 1 h (liquid-to-solid ratio of 7:1), the oxygen pressure was 1.2 MPa, the temperature was maintained at 160°C, and the leachate was filtered to obtain the leachate. The sponge copper was leached in an autoclave, and the copper leaching rate was 99.45%, the chlorine leaching rate was 98.89%, and the iron was converted into hematite (Fe3O4) during the leaching process and remained in the leaching residue. The iron leaching rate was <4%. The leachate contained Cu 80.5 g / L, Fe 0.56 g / L, and Si 0.23 g / L. (3) Preparation of cuprous chloride: copper powder is added to the leachate to prepare cuprous chloride precipitate, which is filtered to obtain a purified leachate; the purified leachate contains less than 0.4 g of iron, less than 0.23 g of chlorine, and less than 0.5 g of silicon. The obtained cuprous chloride precipitate can be used as a catalyst for the production of methylchlorosilane and returned to the previous process flow for use; (4) Preparation of metallic copper by electrowinning; the Cu content of the purified leaching solution was adjusted to 45 g / L, the sulfuric acid concentration to 180 g / L, and the current density to 180 mA / m 2 , cathode copper is obtained, and the prepared cathode copper meets the A-level cathode copper standard in GBT 467-2010 cathode copper standard.

Claims

1. A method for comprehensive utilization and recovery of waste organic silicon contacts, characterized in that: The method for recovering copper from waste organic silicon contacts includes desiliconization, iron removal, cuprous chloride preparation, and copper preparation steps, specifically including: A. Desiliconization: 1) Leaching the waste organosilicon contact with hydrochloric acid under oxidizing conditions, and separating the solid and liquid to obtain a leachate a and a leach residue b; 2) Add iron powder to the leaching solution a to carry out a replacement reaction to obtain sponge copper c and replacement solution d; B. Iron removal: Sulfuric acid solution is added to the sponge copper c to carry out leaching under the condition of oxygen introduction, and the leaching solution e and leaching residue f are obtained after solid-liquid separation; C. Preparation of cuprous chloride: adding copper powder to the leaching solution e for reaction, and performing solid-liquid separation to obtain cuprous chloride precipitate and purified leaching solution g; the cuprous chloride precipitate is used as a catalyst for producing methylchlorosilane; D. Copper preparation: Copper powder or cathode copper and post-electrolysis liquid are prepared by electrolysis of the purified leaching solution g, and the post-electrolysis liquid is returned to step B.

2. The method for comprehensive utilization and recovery of waste organic silicon contacts according to claim 1, characterized in that: A. The concentration of hydrochloric acid in step 1) is 50-200 g / L.

3. The method for comprehensive utilization and recovery of waste organic silicon contacts according to claim 1, characterized in that: The oxidation conditions described in step A1) are adding hydrogen peroxide or passing oxygen.

4. The method for comprehensive utilization and recovery of waste organic silicon contacts according to claim 1, characterized in that: The concentration of the sulfuric acid solution described in step B is 120-180 g / L.

5. The method for comprehensive utilization and recovery of waste organic silicon contacts according to claim 1, characterized in that: The pressure of the oxygen introduced in step B is controlled to be 0.2-1.87 MPa.

6. The method for comprehensive utilization and recovery of waste organic silicon contacts according to claim 1, characterized in that: The amount of copper powder added in step C is 0.5 to 1.0 times the chlorine content.

7. The method for comprehensive utilization and recovery of waste organic silicon contacts according to claim 1, characterized in that: The reaction time in step C is 10 to 120 minutes.

8. The method for comprehensive utilization and recovery of waste organic silicon contacts according to claim 1, characterized in that: The copper powder prepared by electrowinning in step D is obtained by adjusting the copper content of the purified leaching solution to 1-20 g / L, the sulfuric acid concentration to 20-60 g / L, and the current density to 1000-3000 mA / m 2 .

9. The method for comprehensive utilization and recovery of waste organic silicon contacts according to claim 1, characterized in that: In step D, the cathode copper is prepared by electrowinning by adjusting the copper content of the purified leaching solution to 40-60 g / L, the sulfuric acid concentration to 150-200 g / L, and the current density to 150-230 mA / m 2 .

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