CN104843721A - Organic silicon waste contact recovery method - Google Patents

Abstract

The invention relates to an organic silicon waste contact recovery method which includes the steps: (1) calcining an organic silicon waste contact and removing surface carbon deposits; (2) leaching, filtering and washing the organic silicon waste contact treated in the step (1) in ammonia-ammonium salt mixed solution containing oxidizing agents, and drying filter residues to obtain silicon containing solid residues; (3) adding acid liquor into the silicon containing solid residues obtained in the step (2), and soaking, separating, washing and drying the silicon containing solid residues to obtain silicon powder; (4) dispersing the silicon powder obtained in the step (3) in water, controlling temperature and activating the silicon powder to obtain suspending liquid, adding a catalyst into the suspending liquid, heating and stirring the suspending liquid, performing reaction, and performing suction filtration after standing to obtain silica solution. The method is low in cost and simple to operate, materials are easily obtained, and large-scale popularization is easily performed.

Description

A kind of recycling method of organosilicon waste contacts

technical field

The invention relates to the field of recycling organosilicon waste contacts, in particular to a method for preparing silica sol by recycling and treating organosilicon waste contacts.

Background technique

Methylchlorosilane is the most important monomer for the preparation of silicone polymers. Among them, dimethyldichlorosilane [M ₂ ] is used in the largest amount, accounting for about 90% of methylchlorosilane. In the fluidized bed reactor producing _M2 , silicon powder and copper catalyst are mixed to form an active contact body. As the reaction time prolongs, more and more deposits will be deposited on the contact body surface, which will reduce the activity of the contact body and lead to M ₂ Selectivity is reduced. At this time, the mixture of unreacted silicon powder and catalyst needs to be discharged from the reactor, and new contacts are added to facilitate the continuous and stable reaction. In addition, with the continuous consumption of silicon powder during the reaction, the silicon particles continue to become smaller, and the gas-solid separation system of the fluidized bed continuously discharges fine powder with serious surface pollution, and these two parts of waste residue become waste contacts. The main components of these waste contacts are: silicon, copper, carbon, zinc, etc., and their weight contents in waste contacts are 65%-80%, 3%-20%, 1%-10%, 0.05%- 2.0%. Due to the small particles and high activity of copper powder, the waste contact body is prone to oxidation reaction when it encounters air, causing the organic matter and carbon in it to burn and emit pungent white smoke, which is difficult to store and seriously pollutes the environment. pose great dangers. As early as the 1950s, foreign countries have carried out research on the recycling of waste organosilicon contacts. At present, domestic organosilicon companies generally dispose of waste contacts by burying them or selling them to small businesses at low prices. This not only causes serious environmental pollution, but also wastes silicon and copper resources. The presence of heavy metals will pollute the environment; and the waste of expensive elemental silicon results in high cost of organic silicon products.

The comprehensive utilization research of the prior art in this field mainly focuses on the recovery of silicon powder and copper powder (such as CN1083418A, CN1844422A and CN1618840A), and has carried out the research on the processing and utilization of recycled silicon powder (CN1760124A and CN1465524A), such as processed into Qualified silicon powder is returned to the organosilicon monomer production line, or processed into silicon blocks through smelting and utilized. However, in the prior art, the process of comprehensive utilization of organosilicon waste contacts is complicated, and harmful gases are generated during the process, and the utilization rate of silicon cannot reach 100%, and waste silicon powder is still generated.

Solving the "three wastes" problem of waste contacts and carrying out research on environmentally friendly and economical recycling of waste contacts is a technical problem that must be solved in the current organic silicon field. It will reduce costs and reduce pollution for organic silicon companies. It is of great significance to promote the healthy development of my country's organic silicon industry.

Silica sol is a colloidal solution in which nanoscale silica particles are dispersed in water, also known as silicic acid sol, or silica hydrosol. Silica sol has many excellent properties and has great development prospects in inorganic silicon compounds. Due to its corrosion resistance, high temperature resistance, oxidation resistance, large specific surface area, high adsorption, high dispersion, high insulation and other properties, and raw materials Since the 1940s, silica sol has been widely used in machinery manufacturing, petrochemical, textile, electronics and other industrial sectors, especially inorganic With the rise of polymer architectural coatings and the rapid development of the electronics industry, the demand for silica sol has increased rapidly.

There is a need in this field to develop a method for preparing silica sol by recovering silicon powder from organic silicon waste contacts. The method should have the characteristics of simple process, readily available raw materials and convenient operation.

Contents of the invention

In view of the deficiencies in the prior art, one of the purposes of the present invention is to provide a method for preparing silica sol from silicon powder recovered from waste organosilicon contacts, which has significant economic and environmental benefits.

The present invention is specifically realized through the following schemes:

A method for recycling organic silicon waste contacts, said method comprising the steps of:

(1) Calcining the organic silicon waste contact body to remove carbon on its surface;

(2) leaching the waste organosilicon contacts treated in step (1) in an ammonia-ammonium salt mixed solution containing an oxidizing agent, after leaching, filtering, washing, and drying the filter residue to obtain a silicon-containing solid residue;

(3) adding an acid solution to the silicon-containing solid residue obtained in step (2) for soaking, and after soaking, separate, wash and dry to obtain silicon powder;

(4) Disperse the silicon powder obtained in step (3) in water, activate it under temperature control, to obtain a suspension, then add a catalyst, heat and stir for reaction, and after standing still, suction filter to obtain silica sol.

Silicone waste contacts are mainly composed of silicon, copper, and carbon, and contain a small amount of metal components such as tin and zinc. After calcination, ammonia-ammonium salt leaching, and acid solution immersion provided by the present invention, pure silicon powder can be obtained; Silicon can form silicic acid monomer and hydrogen gas with water under alkaline conditions, and silicic acid monomer can form silica sol through its own polymerization. Specifically, silicon powder reacts with water under the action of a catalyst to generate silicic acid molecules, as shown in formula (1):

Si+2OH ^- +H ₂ O→SiO ₃ ^2- +2H ₂ ↑ (1)

The generated active silicic acid has a strong self-agglomeration tendency, so the active silicic acid is softly aggregated to form polysilicic acid. When the concentration of silicic acid in the solution reaches supersaturation, a phase transition reaction occurs, and part of the active silicic acid undergoes dehydration condensation reaction to precipitate crystal nuclei. The reaction is shown in formula (2):

mH ₂ SiO ₃ +nH ₂ SiO ₃ →(n+m)SiO ₂ +(n+m)H ₂ O (2)

When the crystal nucleus is formed, the active silicic acid will be adsorbed on the surface of the crystal nucleus, so that the crystal nucleus will continue to grow, thereby forming a silica sol. The reaction is shown in formula (3):

nSiO ₂ +H ₂ SiO ₃ →(n+1)SiO ₂ +H ₂ O (3).

The calcination temperature in the step (1) of the present invention is 300-800°C, such as 320°C, 350°C, 370°C, 450°C, 480°C, 562°C, 650°C, 730°C, 775°C, etc.; the calcination time is 0.5- 4h, such as 0.8h, 1.2h, 1.6h, 2.3h, 2.8h, 3.3h, 3.8h, etc.

Preferably, the calcination temperature in step (1) is 500-600°C; the calcination time is 0.5-2h.

Preferably, the calcination in step (1) is carried out in a muffle furnace, tube furnace or box furnace.

During the synthesis process of organosilicon monomer, a carbon layer will be deposited on the surface of silicon powder to form carbon deposits, which will affect the subsequent reaction activity. Therefore, the present invention can remove the carbon deposits on the surface of waste contacts by calcining the waste contacts.

The oxidizing agent in the ammonia-ammonium salt mixed solution containing the oxidizing agent in step (2) of the present invention is any one or a combination of at least two of air, oxygen or hydrogen peroxide.

Preferably, the ammonia-ammonium salt in step (2) contains both ammonia water and ammonium salt, and the ammonium salt is any one or a combination of at least two of ammonium chloride, ammonium carbonate or ammonium bicarbonate.

Preferably, the molar ratio of ammonia water to ammonium salt in the oxidant-containing ammonia-ammonium salt mixed solution in step (2) is 1:1.5 to 5, such as 1:1.6, 1:1.9, 1:2.3, 1:2.6, 1:3.5, 1:4.2, 1:4.8, etc.

Preferably, in the ammonia-ammonium salt mixed solution containing the oxidizing agent described in step (2), the mass ratio of the ammonia-ammonium salt to the leached organosilicon waste contact body is 0.2 to 1:1, such as 0.2:1, 0.5: 1, 0.6:1, 0.8:1, etc.

The leaching temperature in the step (2) of the present invention is 20 to 100°C, such as 25°C, 32°C, 38°C, 46°C, 55°C, 68°C, 75°C, 88°C, 95°C, etc., and the leaching time is 1～8h.

Preferably, the leaching temperature in step (2) is 20-70° C., and the leaching time is 3-5 hours.

The acid solution in step (3) of the present invention is selected from any one or a combination of at least two of nitric acid, sulfuric acid, hydrochloric acid or phosphoric acid;

Preferably, the concentration of H ⁺ in the acid solution is 2-10 mol/L, such as 3 mol/L, 5 mol/L, 9 mol/L, etc.;

Preferably, the mass ratio of the added amount of the acid solution to the silicon-containing solid residue is 0.5˜1:1.

The soaking temperature in the step (3) of the present invention is 20～60°C, such as 23°C, 25°C, 36°C, 42°C, 48°C, 55°C, etc., and the soaking time is 1～10h; preferably the soaking temperature is 20°C. ～60℃, soaking time is 3～5h.

The mass ratio of silicon powder and water in the step (4) of the present invention is 1:1-20, such as 1:2, 1:6, 1:12, 1:15, 1:18, 1:19, etc.

The catalyst in the step (4) of the present invention is selected from any one or a combination of at least two of sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia water, sodium silicate or potassium silicate.

Preferably, the mass ratio of the catalyst and silicon powder in step (4) is 0.02-0.1:1, such as 0.04:1, 0.06:1, 0.12:1, 0.15:1, 0.18:1, etc.

The heating and stirring temperature in step (4) of the present invention is 30-100°C, such as 40°C, 50°C, 68°C, 85°C, 92°C, etc., and the time is 3-10h;

Preferably, the temperature of heating and stirring in step (4) is 80-90° C., and the time is 8-10 hours;

Preferably, the standing time in step (4) is more than 5h, such as 6h, 8h, 11h, 16h, 20h, 23h, 25h, etc., preferably more than 10h.

The surface of silicon powder contains an inert film, mainly silicon dioxide film, which can passivate the internal substances and prevent the reaction from happening. The invention activates before reacting with the catalyst, which can remove the oxide layer on the surface of the silicon powder, increase the reaction activity, and make the reaction more likely to occur, otherwise the silicon powder in a passivated state will prolong the time required for the reaction.

As a preferred technical solution, the method for recycling organic silicon waste contacts of the present invention includes the following steps:

(1) Calcining the waste organosilicon contacts at 300-800°C for 0.5-4 hours to remove the carbon deposits on the surface of the waste contacts;

(2) Add an ammonia-ammonium salt mixed solution containing an oxidant to the sample obtained in step (1) for leaching, the leaching temperature is 20-100°C, the leaching time is 1-8h, and after filtering, washing and drying, the obtained Silicon-containing solid residue;

(3) adding acid solution to the silicon-containing solid residue obtained in step (2), soaking for 1-10 hours at a temperature of 20-60° C., and obtaining silicon powder after separation, washing and drying;

(4) Fully mix the silicon powder obtained in step (3) with water to obtain a mixed suspension, and then activate the reaction at a temperature of 30-100° C. for 10-60 minutes; add a catalyst to the obtained mixed suspension, and heat the reaction, wherein The mass ratio of the amount of the added catalyst to the silicon powder obtained in step (3) is 0.02:1-0.1:1. After the reaction, solid-liquid separation is carried out to remove unreacted silicon powder, and the obtained solution is silica sol.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention provides the silicon powder with higher purity obtained by calcination, ammonia leaching (ammonia-ammonium salt leaching) and acid leaching using the solid residue waste contacts of the organic silicon synthesis industry, and then dispersed in an aqueous solution containing an alkaline catalyst The method of obtaining silica sol, which saves production costs and has obvious economic benefits; reduces the pollution of waste contacts to the environment and has obvious environmental benefits;

(2) The method provided by the invention can prepare silicon powder with higher purity, which not only avoids environmental pollution caused by heavy metal discharge, but also realizes the recycling of materials;

(3) The method provided by the invention is easy to operate and low in cost; the reagents used are common in the market, the cost of materials is low, and it is easy to realize large-scale production.

Description of drawings

Fig. 1 is the XRD spectrogram of the silicon powder that embodiment 1 step (3) obtains;

Fig. 2 is the SEM figure that embodiment 1 makes silica sol;

Fig. 3 is the SEM image of the silica sol provided in the comparative example.

Detailed ways

In order to facilitate understanding of the present invention, the present invention enumerates the following examples. It should be clear to those skilled in the art that the embodiments are only for helping to understand the present invention, and should not be regarded as specific limitations on the present invention.

Example 1

A method for recycling organic silicon waste contacts, comprising the steps of:

(1) Weigh 100g of waste contacts and put them into a muffle furnace for calcination at 500°C for 1 hour to remove carbon deposits on the surface of the particles;

(2) Add 17g of ammonium carbonate, 36g (25.0wt%) ammonia water, and 200mL of water to the solid obtained in step (1), at 20°C, stir and leach for 3 hours with air, after the leaching is complete, suction filter, wash, and dry A silicon-containing solid residue is obtained;

(3) Add 100mL of 20wt% hydrochloric acid to the silicon-containing solid residue obtained in step (2), soak at 20°C for 3h, dissolve various metal elements therein, then filter under reduced pressure, and wash the filter residue with water to pH ≈ 7, then Vacuum dry at 90°C for 2 hours in a vacuum drying oven to obtain silicon powder; the acid solution (hydrochloric acid) can be reused until it can no longer be used, and then neutralized with sodium hydroxide to pH ≈ 7 and discharged; the prepared silicon powder has a purity of 97.3%;

(4) Take 15g of the silicon powder obtained in step (3), add 200mL of water to disperse, and activate at 80°C for 30min to obtain a suspension; then add 0.5g of sodium hydroxide, stir and react at 80°C for 8h; then let stand overnight, Then suction filter to remove the unreacted silicon particles to obtain the silica sol.

Performance Testing:

The silicon powder that embodiment 1 reclaims from waste contacts is carried out XRD test on the X 'Pert PRO MPD type multifunctional X-ray diffractometer that Holland Panalytical Company (Panalytical) produces; Result is as shown in Figure 1, and Figure 1 It is the XRD spectrogram of the silicon powder that embodiment 1 step (3) obtains, and the diffraction peak wherein is the characteristic diffraction peak of silicon, does not have other miscellaneous peaks, shows that adopts this method to realize the purification of silicon;

The silica sol prepared in Example 1 was used to observe the surface morphology of the JSM6700 field emission scanning electron microscope produced by Japan Electronics Corporation; FIG. 2 is an SEM image of the silica sol prepared in Example 1.

Example 2

A method for recycling organic silicon waste contacts, comprising the steps of:

(1) Weigh 100g of waste contacts and put them into a muffle furnace for calcination at 500°C for 30 minutes to remove carbon deposits on the surface of the particles;

(2) Add 22.5g of ammonium carbonate, 40g (25.0wt%) ammonia water, and 200mL of water to the solid obtained in step (1), at 40°C, stir and leaching with air for 3h, after leaching is complete, suction filter and wash , dried to obtain a silicon-containing solid residue;

(3) Add 100mL of 20wt% hydrochloric acid to the silicon-containing solid residue obtained in step (2), soak at 30°C for 3h, dissolve various metal elements therein, and then filter under reduced pressure; the filter residue is washed with water to pH ≈ 7, and then Vacuum dry in a vacuum oven at 90°C for 2 hours to obtain silicon powder; the acid solution (hydrochloric acid) can be reused until it can no longer be used, and then neutralized with sodium hydroxide to pH ≈ 7 and discharged; the prepared silicon powder has a purity of 96.8%;

(4) Take 15g of silicon powder obtained in step (3), add 200mL of water to disperse, and activate at 80°C for 30min to obtain a suspension; then add 0.5g of sodium hydroxide, stir and react at 90°C for 8h; let the liquid stand overnight , and then suction filtered to remove the unreacted silicon particles to obtain silica sol.

Example 3

A method for recycling organic silicon waste contacts, comprising the steps of:

(1) Weigh 100g of waste contacts and put them into a muffle furnace for calcination at 550°C for 1 hour to remove carbon deposits on the surface of the particles;

(2) Add 20g ammonium carbonate, 45.5g (25.0wt%) ammoniacal liquor, 200mL water to the solid obtained in step (1), at 60°C, stir and leach for 3h in air, after the leaching is complete, suction filter and wash, Dry to obtain a silicon-containing solid residue;

(3) Add 100mL of 20wt% hydrochloric acid to the silicon-containing solid residue obtained in step (2), soak at 40°C for 3h, dissolve various metal elements therein, then filter under reduced pressure, and wash the filter residue with water to pH ≈ 7, then Vacuum dry at 90°C for 2 hours in a vacuum drying oven to obtain silicon powder; the acid solution (hydrochloric acid) can be reused until it can no longer be used, and then neutralized with sodium hydroxide to pH ≈ 7 and discharged; the prepared silicon powder has a purity of 97.2%;

(4) Take 25g of the silicon powder obtained in step (3), add 200mL of water to disperse, and activate at 80°C for 30min to obtain a suspension; then add 1.0g of sodium hydroxide, stir and react at 80°C for 8h; then let stand overnight, Then suction filter to remove the unreacted silicon particles to obtain the silica sol.

Example 4

A method for recycling organic silicon waste contacts, comprising the steps of:

(1) Weigh 100g of waste contacts and put them into a muffle furnace for calcination at 550°C for 2 hours to remove carbon deposits on the surface of the particles;

(2) Add 25g of ammonium bicarbonate, 53.5g (25.0wt%) ammonia water, and 200mL of water to the solid obtained in step (1), and stir and leach for 5h at 40°C. After the leaching is completed, suction filter and wash , dried to obtain a silicon-containing solid residue;

(3) Add 100mL of 20wt% nitric acid to the silicon-containing solid residue obtained in step (2), soak at 25°C for 3h, dissolve various metal elements therein, then filter under reduced pressure, and wash the filter residue with water to pH ≈ 7, then Vacuum dry at 90°C for 2 hours in a vacuum drying oven to obtain silicon powder; the acid solution (nitric acid) can be reused until it can no longer be used, and then neutralized with sodium hydroxide to pH ≈ 7 and discharged; the prepared silicon powder has a purity of 96.8%;

(4) Take 25g of the silicon powder obtained in step (3), add 200mL of water to disperse, and activate at 80°C for 30min to obtain a suspension; then add 1.0g of sodium hydroxide, stir and react at 90°C for 8h; then let stand overnight, Then suction filter to remove the unreacted silicon particles to obtain the silica sol.

Example 5

A method for recycling organic silicon waste contacts, comprising the steps of:

(1) Weigh 100g of waste contacts and put them into a tube furnace at 500°C for 30min to remove carbon deposits on the particle surface;

(2) Add 22.7g ammonium bicarbonate, 58.5g (25.0wt%) ammoniacal liquor, 200mL water to the solid obtained in step (1), at 50°C, stir and leach for 5h in air, after the leaching is complete, suction filtration, Washing and drying to obtain a silicon-containing solid residue;

(3) Add 100mL of 20wt% nitric acid to the silicon-containing solid residue obtained in step (2), soak at 30°C for 3h, dissolve various metal elements therein, and then filter under reduced pressure; the filter residue is washed with water to pH ≈ 7, and then Vacuum dry at 90°C for 2 hours in a vacuum drying oven to obtain silicon powder; the acid solution (nitric acid) can be reused until it can no longer be used, and then neutralized with sodium hydroxide until pH ≈ 7 and discharged; the prepared silicon powder has a purity of 97.4%;

(4) Take 30g of silicon powder obtained in step (3), add 200mL of water to disperse, activate at 80°C for 30min, and obtain a suspension; then add 1.0g of sodium hydroxide, stir and react at 90°C for 8h; let the liquid stand overnight , and then suction filtered to remove the unreacted silicon particles to obtain silica sol.

Example 6

A method for recycling organic silicon waste contacts, comprising the steps of:

(1) Weigh 100g of waste contacts and put them into a tube furnace for calcination at 500°C for 1 hour to remove carbon deposits on the particle surface;

(2) Add 25g ammonium carbonate, 35.5g (25.0wt%) ammoniacal liquor, 200mL water to the solid obtained in step (1), at 60°C, stir and leach for 5h in air, after leaching, suction filter and wash, Dry to obtain a silicon-containing solid residue;

(3) Add 100mL of 20wt% hydrochloric acid to the silicon-containing solid residue obtained in step (2), soak at 50°C for 5h, dissolve various metal elements therein, then filter under reduced pressure, and wash the filter residue with water to pH ≈ 7, then Vacuum dry at 90°C for 2 hours in a vacuum drying oven to obtain silicon powder; the acid solution (hydrochloric acid) can be reused until it can no longer be used, and then neutralized with sodium hydroxide to pH ≈ 7 and discharged; the prepared silicon powder has a purity of 96.9%;

(4) Take 20g of the silicon powder obtained above, add 200mL of water, and activate at 80°C for 30min to obtain a suspension; then add 0.5g of sodium hydroxide, stir and react at 80°C for 10h; then let stand overnight, and then suction filter, The unreacted silicon particles are removed to obtain the silica sol.

Example 7

A method for recycling organic silicon waste contacts, comprising the steps of:

(1) Weigh 100g of waste contacts and put them into a tube furnace for calcination at 550°C for 1 hour to remove carbon deposits on the particle surface;

(2) Add 30g of ammonium carbonate, 42.6g (25.0wt%) ammonia water, and 200mL of water to the solid obtained in step (1), and stir and leaching with air for 5 hours at 60°C. After the leaching is completed, suction filter and wash , dried to obtain a silicon-containing solid residue;

(3) Add 100mL of 20wt% hydrochloric acid to the silicon-containing solid residue obtained in step (2), soak at 50°C for 7h, dissolve various metal elements therein, then filter under reduced pressure, and wash the filter residue with water to pH ≈ 7, then Vacuum dry at 90°C for 2 hours in a vacuum drying oven to obtain silicon powder; the acid solution (hydrochloric acid) can be reused until it can no longer be used, and then neutralized with sodium hydroxide to pH ≈ 7 and discharged; the prepared silicon powder has a purity of 97.3%;

(4) Take 30g of the silicon powder obtained above, add 200mL of water, and activate at 80°C for 30min to obtain a suspension; then add 1.0g of sodium hydroxide, stir and react at 80°C for 10h; then let stand overnight, and then suction filter, The unreacted silicon particles are removed to obtain the silica sol.

Example 8

A method for recycling organic silicon waste contacts, comprising the steps of:

(1) Weigh 100g of waste contacts and put them into a tube furnace for calcination at 600°C for 1 hour to remove carbon deposits on the surface of the particles;

(2) Add 30 g of ammonium bicarbonate, 68.3 g (25.0 wt %) of ammonia water, and 200 mL of water to the solid obtained in step 1, and at 70° C., stir and leaching with air for 5 h, after leaching is completed, suction filter and wash, Dry to obtain a silicon-containing solid residue;

(3) Add 100mL of 20wt% hydrochloric acid to the silicon-containing solid residue obtained in step (2), soak at 60°C for 5h, dissolve various metal elements therein, then filter under reduced pressure, and wash the filter residue with water to pH ≈ 7, then Vacuum dry at 90°C for 2 hours in a vacuum drying oven to obtain silicon powder; the acid solution (hydrochloric acid) can be reused until it can no longer be used, and then neutralized with sodium hydroxide until pH ≈ 7; the prepared silicon powder has a purity of 97.5%;

(4) Take 30g of the silicon powder obtained above, add 200mL of water, and activate at 80°C for 30min to obtain a suspension; then add 1.0g of sodium hydroxide, stir and react at 90°C for 10h; then let stand overnight, and then suction filter, The unreacted silicon particles are removed to obtain the silica sol.

comparative example

Commercially available silica sol was purchased from Beijing Hongxing Guangsha Chemical Building Materials Co., Ltd. hx type silica sol.

Fig. 3 is the SEM image of the silica sol provided in the comparative example; the silica sols shown in Fig. 2 and Fig. 3 are all spherical.

The performance test result of embodiment and comparative example is shown in Table 1:

The performance test result of the silica sol that table 1 embodiment and comparative example provide

The performance test methods are: SiO ₂ content: high temperature burning method; Na ₂ O content and average particle size: titration method; pH: PHS-3C pH meter; density: Baume hydrometer.

The industry standard is:

SiO ₂ content: ≥20wt%; Na ₂ O content: ≤0.4wt%; pH: 9.0-10.0; 25°C density: 1.12-1.21g/cm ³ ; average particle size, ≤100nm.

The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow process can be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (9)

1. a recovery method for abandoned catalyst in direct synthesis methylchlorosilane, is characterized in that, described method comprises the steps:

(1) calcine abandoned catalyst in direct synthesis methylchlorosilane, remove its area carbon;

(2) abandoned catalyst in direct synthesis methylchlorosilane in the ammonia-ammonium salt mixing solutions containing oxygenant after leaching step (1) process, leaches complete, filters, washing, and dry filter residue, obtains silicon-containing solid residue;

(3) add acid solution in the silicon-containing solid residue obtained to step (2) to soak, soak after terminating, be separated, washing, obtain silica flour after drying;

(4) be dispersed in water by the silica flour that step (3) obtains, temperature control activates, and obtain suspension, add catalyzer afterwards, heated and stirred is reacted, and after leaving standstill, suction filtration obtains silicon sol.

2. method as claimed in claim 1, it is characterized in that, step (1) described calcining temperature is 300 ~ 800 DEG C; Calcination time is 0.5 ~ 4h;

Preferably, step (1) described calcining temperature is 500 ~ 600 DEG C; Calcination time is 0.5 ~ 2h;

Preferably, step (1) described calcining is carried out in retort furnace, tube furnace or box-type furnace.

3. method as claimed in claim 1 or 2, is characterized in that, step (2) is described is the combination of any a kind or at least 2 kinds in air, oxygen or hydrogen peroxide containing the oxygenant in the ammonia-ammonium salt mixing solutions of oxygenant;

Preferably, the described ammonia-ammonium salt of step (2) is simultaneously containing ammoniacal liquor and ammonium salt, and described ammonium salt is the combination of any a kind or at least 2 kinds in ammonium chloride, volatile salt or bicarbonate of ammonia;

Preferably, step (2) is described is 1:1.5 ~ 5 containing the mol ratio of ammoniacal liquor and ammonium salt in the ammonia-ammonium salt mixing solutions of oxygenant;

Preferably, step (2) is described containing in the ammonia-ammonium salt mixing solutions of oxygenant, and the mass ratio of the abandoned catalyst in direct synthesis methylchlorosilane of ammonia-ammonium salt and leaching is 0.2 ~ 1:1.

4. method as described in one of claims 1 to 3, is characterized in that, step (2) described leaching temperature is 20 ~ 100 DEG C, and leaching time is 1 ~ 8h;

Preferably, step (2) described leaching temperature is 20 ~ 70 DEG C, and leaching time is 3 ~ 5h.

5. method as described in one of Claims 1 to 4, is characterized in that, step (3) described acid solution is selected from the combination of any a kind or at least 2 kinds in nitric acid, sulfuric acid, hydrochloric acid or phosphoric acid;

Preferably, H in described acid solution ⁺concentration be 2 ~ 10mol/L;

Preferably, the add-on of described acid solution and the mass ratio of silicon-containing solid residue are 0.5 ~ 1:1.

6. method as described in one of Claims 1 to 5, is characterized in that, step (3) described soaking temperature is 20 ~ 60 DEG C, and soak time is 1 ~ 10h; Preferred described soaking temperature is 20 ~ 60 DEG C, and soak time is 3 ~ 5h.

7. method as described in one of claim 1 ~ 6, is characterized in that, the mass ratio of step (4) described silica flour and water is 1:1 ~ 20.

8. method as described in one of claim 1 ~ 7, is characterized in that, step (4) described catalyzer is selected from the combination of any a kind or at least 2 kinds in sodium hydroxide, potassium hydroxide, lithium hydroxide, ammoniacal liquor, water glass or potassium silicate;

Preferably, the mass ratio of step (4) described catalyzer and silica flour is 0.02 ~ 0.1:1.

9. method as described in one of claim 1 ~ 8, is characterized in that, the temperature of step (4) described heated and stirred is 30 ~ 100 DEG C, and the time is 3 ~ 10h;

Preferably, the temperature of step (4) described heated and stirred is 80 ~ 90 DEG C, and the time is 8 ~ 10h;

Preferably, step (4) described time of repose is more than 5h, preferred more than 10h.