CN114591360A

CN114591360A - Separation treatment system and recycling technology of organic silicon slurry residues

Info

Publication number: CN114591360A
Application number: CN202011298588.5A
Authority: CN
Inventors: 周曦东; 刘兰英
Original assignee: Beijing Nastek Nano Technology Co ltd
Current assignee: Zhejiang Xingneng Electronic Materials Co ltd
Priority date: 2020-11-19
Filing date: 2020-11-19
Publication date: 2022-06-07

Abstract

The invention mainly comprises the following steps: 1. by selecting a special solvent for extraction and a special centrifugal gravity settling method, the high-boiling-point substances of the liquid slurry of the slurry residue are completely separated and recycled, and the potential safety hazard in the liquid slurry is eliminated. 2. The liquid slurry residue recycling method is special, and comprises the steps of directly distilling low boiling point components to be directly utilized and directly converting the components to be utilized in the solution. 3. The solid slag slurry is washed and dissolved by special water to obtain solid, the solid is easy to filter and separate to obtain pure solid simple substance silicon powder with the content of more than 95 percent, and the pure solid simple substance silicon powder can be used for producing silicon substances such as silicon dioxide, silicon monoxide, silicon carbide, silicon nitride and the like. 4. The liquid obtained by washing the solid slag slurry with special water does not contain metal elements such as reducing copper, aluminum, tin, iron, calcium, nickel and the like, is enriched in an aqueous solution in the form of sulfate or chloride, can be enriched by ion exchange and is reduced and recovered, wherein the recovery rate of copper reaches more than 90%.

Description

Separation treatment system and recycling technology of organic silicon slurry residues

Technical Field

The invention relates to a technology for separating and recycling organic silicon slurry residues, and belongs to the field of comprehensive utilization of organic silicon slurry residues.

Background

The organosilicon residues are waste generated in the process of synthesizing organosilicon monomers, mainly comprise a large amount of high-boiling residues and a small amount of unreacted silicon powder and copper powder carried out by a fluidized bed, and if the organosilicon residues are exposed in the air, the organosilicon residues can be burnt or form strong acid mist or strong acid liquid, so the environment can be seriously polluted if the organosilicon residues are directly discharged, the solid content of the residues after the organosilicon synthesis products are subjected to pollution-free treatment and are subjected to rotational separation and fine stuffing separation is about 25 percent, and the components of the residues mainly comprise silicon, copper, zinc, carbon, trace aluminum, calcium, a shackle and the like; the main components in the liquid phase are (CH3)4Cl2Si2, (CH3)2Cl4Si2, other monosilane with low boiling point, Si-O-Si and other high-boiling substances with high boiling point, wherein the total amount of (CH3)4Cl2Si2 and (O)2Cl4Si2 accounts for 50-70% of the whole pulp. No mature process exists for the reduction treatment and hydrolysis of the organic silicon slurry residue in China. The reduction treatment basically adopts original precipitation separation, some processes adopt a flash evaporation tank evaporation separation process, but the effects are not good, the high-boiling residues recovered by the precipitation separation and the flash evaporation tank evaporation separation are few, and a large amount of high-boiling residues still exist in the separated pulp residue, so that the load of a hydrolysis system is large. The slurry residue hydrolysis process is various, each plant is generally constructed according to the experience of technicians, the hydrolysis is still incomplete, hydrolysis glue chain substances are generated in the hydrolysis process due to more residual high-boiling substances and the difference of hydrolysis control conditions, the glue chain death phenomenon is easy to occur, a large amount of hydrogen chloride gas is generated, safety accidents are easy to occur, the environment is easy to be polluted, and the environment is not protected. Therefore, the traditional waste residue slurry treatment method has the problems of complicated operation, incomplete treatment of clean waste, easy environmental pollution and the like; if the accumulation method is adopted for treatment, the pollution is serious, and potential safety hazards exist. The domestic waste residue slurry treatment technology is still a blank, and at present, only the blockage of a warehouse can be overstocked or copper can be simply recovered, so that the environmental protection problem is not fundamentally solved, and the waste of chlorine is not caused.

US Pat 4221691 provides a method of treating waste pulp: a small amount of mineral oil is added to the slurry to improve the handling characteristics of the hydrolysate. However, this method has disadvantages in that: the residue slurry is not fully contacted with a hydrolysis medium, the hydrolysis speed is relatively slow, and the obtained hydrolysate is viscous and difficult to separate from the system; in addition, the method requires that in the organosilicon monomer molecules of the slurry, the number of chlorine groups attached to each silicon atom is not less than 3, but most of the monomers in the slurry do not meet the requirements thereof, so that most of the slurries cannot be treated by the method; and the addition of mineral oil in the hydrolysis process increases the waste treatment cost, adds a new pollution source and does not meet the requirement of environmental protection.

US 4408030 provides a waste treatment process for chlorosilane-containing multi-streams comprising the steps of: (A) determining the average SICL functionality of the stream; (B) combining at least two streams such that the SICL functionality of the combined stream is greater than or equal to 2.8; (C) hydrolyzing the mixture of hydrolysis media at a temperature between 50 ℃ and the boiling point of the hydrolysis media, and (D) separating the hydrolysis media to obtain colloidal particles which are easy to handle during subsequent processing, convenient to transport and further to handle. Wherein the hydrolysis medium is selected from the group consisting of water, calcium chloride solution, and concentrated hydrochloric acid solution. The hydrolysis temperature is preferably 60 to 90 ℃. The HCL produced during hydrolysis can be recovered. The crumb in this process may be washed with water to further reduce the chlorine content of the crumb. If the hydrolysis solution initially contains only water, hydrochloric acid is formed as the hydrolysis proceeds, and hydrogen chloride is desorbed when the hydrochloric acid in the water is saturated. Hydrochloric acid and inorganic chloride may be added to the hydrolysis medium to saturate the hydrolysis solution so that hydrogen chloride is evolved at the beginning of the hydrolysis. The hydrolysate is separated from the liquid by filtration or centrifugation, the obtained solid hydrolysate particles are non-adherent, easy to handle, convenient to transport and further to process, and the hydrolysate can be washed with water one or more times to further reduce the chlorine content in the hydrolysate. The method has the following disadvantages that firstly, water, calcium chloride solution or concentrated hydrochloric acid solution is used as a hydrolysis medium, hydrolysis particles are fine and are not easy to extract from a reaction kettle; secondly, the concentration of chloride ions adsorbed on the surface of the hydrolysate reaches more than 10 percent, and if the chloride ions are reduced to a lower concentration, a large amount of water is needed for washing, so that the discharge amount of the waste acid liquid is large.

EP 867442A2 describes a process for the hydrolysis of methylchlorosilanes by-products which results in at least two phases, which comprises hydrolysis of the by-products by addition of an aqueous medium which may contain surfactants and which has a pH of at least about 7 and a temperature of above 0 ℃. One of the phases is an inert solid and the second phase is an aqueous solution, substantially free of metals, which may be discharged with or without treatment. Solids may be separated by filtration, precipitation, flotation or centrifugation techniques, and the aqueous medium may be separated to recover salts, silicates or discharged to a wastewater treatment facility. The surfactant is an anionic or nonionic surfactant, preferably a non-surfactant. The process has the advantages that: firstly, the method reduces the concentration of heavy metals in the hydrolysate, solves the problem of waste treatment, and the product obtained by the hydrolysis process is inert, has high flash point, no gas precipitation, no viscosity, no dust, easy flowing and easy treatment and transportation. Secondly, copper is enriched in the solid hydrolysate and can be fully recovered. The disadvantages are that: hydrogen chloride which is one of reaction products is neutralized by alkali in a hydrolysis medium to form salt, and a part of resources are wasted; in addition, the reduced copper contained in the solid hydrolysate is easy to spontaneously combust under the conditions of heat, long-time irradiation of sunlight or accumulation, and is an important safety hazard.

DE 4116925A 1 describes a process for hydrolyzing methylchlorosilanes by-products by preparing a raffinate consisting of a direct mixture of chloro-and/or organochlorosilanes at a temperature of from 20 ℃ to 100 ℃ (predominantly between 35 ℃ and 60 ℃) in a concentration of 20%

70% (mainly 40% to 60% concentration) sulfuric acid is mixed and subjected to neutralization reaction with the separated hydrolysate, calcium hydroxide, calcium oxide, calcium carbonate or a mixture thereof, until a floating solid mainly composed of polysiloxane or alginic acid is produced. By mixing with calcium hydroxide, calcium oxide, calcium carbonate or mixtures thereof, a dry suspended solid is produced from the original wet hydrolysate. This solid comprises a maximum of 5% wt of residual chloride and a small amount of 20%water, waste specific gravity total 0.5

1 g/ml. The separated liquid phase is again hydrolyzed or used to wash and dry the conversion reactants, gaseous hydrogen chloride. The main disadvantage of this process is that the slurry phase is completely hydrolyzed, resulting in waste.

CN 106220666A discloses a treatment system and a treatment method of organic silicon slurry, which comprises an organic silicon slurry source, a heating and evaporating device and a condensation and recovery device, wherein an inlet of the heating and evaporating device is connected with the organic silicon slurry source, the heating and evaporating device provides a low-pressure environment and heats the organic silicon slurry; the inlet of the condensation recovery device is connected with the upper end outlet of the heating evaporation device, and the gas-phase material evaporated by heating the organic silicon slurry slag is condensed and recovered. Although part of the high-boiling-point intractable organosilicon slurry can be recovered by the reduced pressure distillation method, the slurry residue has complex components and small difference of actual boiling points, so that the purity of the fraction after recovery is not solved at all, and the recovery rate of the whole liquid slurry is low.

CN1618840A introduces a method for treating waste residue slurry in the process of synthesizing organosilicon monomers. Most of high-boiling residues are recovered by centrifugal gravity settling separation, and the hydrolysate obtained by hydrolyzing the residual slurry is easy to extract and does not contain reducing copper, so that potential safety hazards are eliminated; copper in the slurry is enriched in the hydrolysis solution in the form of copper sulfate and can be recovered by a reduction method, and the recovery rate of the copper reaches more than 95 percent; the solid hydrolysate basically meets the requirement of environmental protection, but the method has very low recovery rate of the liquid slurry, and actually only solves the problem of the recovery rate of copper in the solid slag.

CN106170325B invention discloses a method for recovering hydrohalosilanes from reaction residues. Passing an inorganic halosilane slurry comprising (i) a tetrahalosilane, a trihalosilane, a dihalosilane, or any combination thereof removes heavies as the slurry passes through the thin film dryer to remove halosilanes and form a solid residue comprising silicon particles. The method aims at reducing the caking property of liquid reducing materials and solid slag materials and expanding the distillation volatilization speed, but because the area of the film evaporator and the pollution of the slurry slag on the film evaporator influence the heat transfer efficiency limitation, the method can not meet the requirement of large-scale slurry slag treatment capacity at all.

Disclosure of Invention

Aiming at the defects in the prior art, the invention discloses a separation treatment system and a recovery technical method of organic silicon slurry residues. In order to solve the technical problems, the technical scheme of the invention is as follows:

1. an extraction washing treatment system of organic silicon pulp slag comprises an organic silicon pulp slag source, a special solvent, a cosolvent, an air isolation closed stirring kettle, a centrifugal filter device, an ultrafiltration device and a filtrate recovery device, wherein the stirring kettle is connected with an organic silicon slurry residue source, a mixed solvent storage kettle, a centrifugal filter, an inlet and an outlet of an ultrafiltration device and the like by adopting closed pipelines, mixing the slurry residue source and the mixed solvent according to a certain proportion according to the requirements of the slurry residue solid content and viscosity and a centrifugal filter tank, introducing the mixture into a centrifugal filter, extracting and filtering for multiple times to obtain solid filter residue and liquid slurry, and is gathered in a temporary liquid storage tank for ultrafiltration to completely remove solid particles in the liquid to obtain the liquid for further utilization, and the solid in the centrifuge directly enters a solid cleaning kettle, and clean solid silicon powder and further processed filtrate are obtained after multiple times of cleaning and filtering.

Preferably, the separation treatment system further comprises a solvent and cosolvent mixing device, a silica slurry slag and solvent metering device, a coarse centrifugal separation device, a secondary centrifugal separation device, a fine centrifugal separation device, a centrifugal slurry slag solvent re-extraction dissolution stirring device, a solid slurry slag re-washing system, a filtering system and a filtrate treatment system.

Further preferably, in the separation treatment system, the separation of the liquid slurry from the solid slurry residue and the ultrafiltration stage of the liquid slurry are completed in a closed environment, and all materials of the device are resistant to corrosion, especially hydrogen chloride and special solvents.

More preferably, the slurry washing device can be heated and can be added with a benzenesulfonate washing synergist and hydrochloric acid or sulfuric acid to improve the washing effect and dissolve copper powder, wherein the temperature is 25-55 ℃, the acidity of the solution is controlled below pH 1, and the washed solid silicon powder can be dried and packaged on line.

2. After solid-liquid separation is carried out on the slurry residue in the scheme, the liquid slurry and a special solvent are recovered together by adopting a fractional rectification mode, wherein low-boiling monosilane such as tetramethylsilane, trimethylchlorosilane, dimethyldichlorosilane, trichloromethylsilane and the like, low-boiling perchlorodisilane such as trichlorosilane, tetrachlorodisilane, pentachlorodisilane, hexachlorodisilane and the like has definite boiling points and can be directly recovered and utilized when the difference between the boiling points and the solvent is large, and the difference between the boiling points and the boiling points of the solvent is small. In the case of high-boiling compounds above 150 ℃, oligomeric chlorosilanes or polyalkylated prepolymers are generally converted directly into hyperbranched compounds by amination or alkoxy groups as special functional materials.

Preferably, trichlorosilane, tetrachlorodisilane, pentachlorodisilane and hexachlorodisilane in the liquid slurry are further purified and converted into silicon nitride and monocrystalline silicon coating materials which meet the electronic grade, and dichlorodisilane is converted into silicon nitride ceramic precursor materials for producing silicon carbide ceramic materials.

The further preferable high boiling point component which can not be cracked and separated is directly converted into a hyperbranched compound through amination or alkoxy, and the hyperbranched compound can be further modified with acrylic acid, silicon rubber raw materials, polyurethane, epoxy resin or amino resin to form a special composite material which is used in a special functional material.

Further preferred high boiling point components which cannot be cracked and separated are directly converted into high molecular functional surfactants through amination or alkoxy, and are directly applied to oil field chemicals or building cement additives and modifiers.

The invention has the beneficial effects that:

the invention can really change the organic silicon pulp residue which is difficult to treat into valuable things, avoids the difficult separation of hydrolysate, low recovery utilization rate of liquid components and incomplete cleaning of solid components by a conventional hydrolysis method through a solvent dilution extraction method, and simultaneously adopts different recovery and utilization methods for each grade of fraction through fractional rectification, the catalyst has high use efficiency and high catalytic cracking conversion rate, so that chlorosilane and high polymer with different boiling points and different application and use values can be respectively produced, the useful liquid in the pulp residue can be basically and completely recovered and utilized, the reduction treatment of the organic silicon pulp residue is realized, the utilization efficiency of useful materials in the pulp residue is improved, the pulp residue treatment cost is reduced, and the production cost is reduced. The annual output is 40 ten thousand tons of chlorosilane devices, 8000 tons of solid slurry residues can be recycled to reach 5000 tons of liquid components every year, and the method has good economic benefit.

The system and the method can not only carry out reduction production on the organic silicon slurry residues, recover most of chlorosilane in the organic silicon slurry residues, carry out hydrolysis neutralization reaction on the residual residues, reduce the hydrolysis difficulty of the residues, improve the hydrolysis degree of waste liquid in the residues, avoid the phenomenon of easy gum chain death in the hydrolysis process, but also greatly reduce the generation of hydrogen chloride gas; in addition, the clear liquid generated by hydrolysis can be used for the production of calcium chloride or the reaction in the process of circulating back hydrolysis, thereby reducing the discharge of waste liquid, improving the degree of treatment of organic silicon pulp slag, and simultaneously realizing energy conservation, environmental protection and income creation. The reaction reduces the discharge of waste liquid, improves the treatment degree of the organic silicon slurry slag, and simultaneously saves energy, protects environment and creates income.

Detailed Description

The present invention will be further described with reference to examples, but the following description is only for the purpose of explaining the present invention and does not limit the contents thereof.

Example 1

Taking 500 kg of pulp slag from a pulp slag raw material buffer tank, inputting the pulp slag into a centrifugal filter, obtaining 300 kg of liquid pulp and 200 kg of solid filter residue through centrifugal filtration, washing and filtering the filter residue with a solvent, repeating the washing and filtering for multiple times, converging 1500 kg of all filtrate, evaporating 1200 kg of the solvent, and rectifying to obtain 225 kg of a re-cleavable organic silicon component A and 135 kg of a component B which cannot be cleaved and has a high boiling point; for solid slag, acid is used for dissolving and washing for three times to obtain 180 kg of silicon powder C, 7 kg of copper is recovered by reducing iron powder, and the recovery rate is 95%.

And (3) re-injecting 225 kg of cleavable organosilicon A into the kettle, and cracking at 245 ℃ by using aluminum trichloride, hydrogen chloride and hydrogen as catalysts to obtain 150 kg of methyldichlorosilane, 50 kg of methyltrichlorosilane and 20 kg of dimethylchlorosilane.

The above description is only one embodiment of the present invention, and not all or only one embodiment, and any equivalent alterations to the technical solutions of the present invention, which are made by those skilled in the art through reading the present specification, are covered by the claims of the present invention.

Claims

1. A separation treatment system and utilization technology of waste residue slurry in the synthetic process of organic silicon monomer comprise the following steps:

a, washing waste residue slurry in the synthesis of an organic silicon monomer for multiple times by using a special solvent, and separating a mixture with more than 98% of liquid slurry by using a centrifugal gravity settling centrifuge for rectification, cracking and conversion of other substances with other purposes;

b, washing the solid waste residue after centrifugation in a special hydrolysis kettle, wherein the hydrolysis medium is an acidic sulfuric acid or hydrochloric acid solution with the pH of 1-2, and a relevant washing synergist is added; a small amount of hydrogen chloride gas containing siloxane is separated out from the liquid phase;

c, performing liquid-solid separation on the washed matter, drying and recycling the solid, and performing subsequent treatment on the liquid phase to recycle copper, iron, aluminum and nickel.

2. The method according to claim 1, wherein the special solvent is a chlorinated hydrocarbon or a fluoroether, and the solvent has a boiling point of 40 to 70 ℃, is a nonflammable inert solvent having good solubility for silicone monomers and oligomers, a low boiling point, is chemically stable, and is not decomposed by heating, and can be recycled for a long period of time.

3. The method according to claim 1, wherein the solvent is washed several times, the liquid mixture is ultrafiltered, and the solvent is stored stably for a long time without separation with the organosilicon monomer or prepolymer and used in the production process of rectification, cracking and conversion of other materials.

4. The method according to claim 1, wherein the liquid separated by extraction of the sludge is recovered by a rectification method and a direct conversion method, wherein the distilled fraction has a higher purity and is directly recovered, and the fraction having a smaller difference in boiling point and a lower purity is converted into different substances by adding other substances, and then the related substances are separated; the polychlorinated disilane and the trichlorosilane with the chlorine atom number less than 3 are catalytically cracked to convert the small molecular monomer, and the high boiling point mixture with the boiling point more than 150 ℃ is directly added with other substances to convert other mixtures for utilization.

5. The method of claim 1 wherein the centrifugal gravity settling separation and liquid ultrafiltration process separation are conducted under a closed inert gas blanket to protect the liquid slurry from absorbing air water.

6. The method as set forth in claim 4, wherein the catalyst in the conversion of the liquid slurry components by the catalytic cracking method is selected from the group consisting of iron chloride, aluminum chloride, hydrogen gas, composite salts MAlX4(M is an alkali metal such as Na, K, Li; X is a halogen such as Cl, Br, F, etc.), organic amines and salts thereof (tertiary amines, N-dimethylaniline, N-dimethylformamide, N-diethylformamide, quaternary amine halides, quaternary phosphine halides, etc.), transition metals such as Pd, Pt, Rh, Ru and Ni and chlorides thereof such as K2PdCl4, (R3P)2PdCl2, (R3P)2PtCl2, (R3P)2 l2, (R is an alkyl group and a phenyl group having 1 to 6 carbon atoms), (Ph3P)2NiCl2, (Me2 PlP) 2Cl 2, (Ph3 PdCo 3P)4PdCo, etc., activated carbon, molecular sieves including natural zeolites such as chabazite, faujasite zeolites, luminescent zeolites, faujasite zeolites, and the like, Clinoptilolite, erionite and artificially synthesized zeolites ZSM-5, ZSM-1l, preferably LZ-Y-64, LZ-Y-74, LZ-M-8, and 1, 2 or more of them as catalysts assisted by a certain amount of hydrogen, chlorine or hydrogen chloride as cracking gas; the compounds in the non-catalytic cracking conversion include nitride-containing and oxide-containing, or self-condensing, polymeric organosilicon high-molecular substances, and these compounds may be silicon-based silicon carbide, silicon nitride precursors, polysiloxanes, polysilazanes, polysilanes, and other acrylic, polyurethane-based graft compounds.

7. The method B of claim 1, wherein the residue after solid-liquid separation is rapidly washed at room temperature or under heating, wherein hydrochloric acid, or sulfuric acid, or alkylbenzene sulfonic acid washing synergist can be added to improve washing speed and effect. .

8. The method according to claim 1C, wherein the washed elemental solid silicon has a high particle content and no hazardous impurity components, and can meet the circulation requirements of common chemicals, and the purity can meet the quality standards for producing silicon dioxide, silicon monoxide, silicon carbide, silicon nitride, and the like.