CN103241739A

CN103241739A - Alkali washing purifying method of silicon carbide filter cake

Info

Publication number: CN103241739A
Application number: CN2013101874732A
Authority: CN
Inventors: 周彬
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-05-16
Filing date: 2013-05-16
Publication date: 2013-08-14
Also published as: WO2014183381A1

Abstract

The invention relates to an alkali washing purifying method of a silicon carbide filter cake, which comprises the following steps of: (1) mixing the silicon carbide filter cake and water at a weight ratio of 1:1 and stirring uniformly; and mixing sodium hydroxide and water at a ratio of 1:2 and stirring uniformly; (2) slowly filling the silicon carbide filter cake suspension into alkaline water to conduct an alkali reaction; and (3) adding water into the silicon carbide suspension after the reaction at a ratio of 1:1, and respectively performing 3-4 times of pressure filtration to obtain a wet product of silicon carbide. Compared with the prior art, the method provided by the invention performs a silicon powder removing alkali reaction by a titration reaction method; the silicon carbide suspension is dropwise added into the alkaline water, the reaction temperature is always controlled at 90 DEG C, gas is uniformly generated, and a boiling state is avoided; the consumption of alkali and water is greatly reduced, the alkali and silicon powder are added at a ratio of 2:1, sufficient reaction can be realized, and the production cost is saved; later alkali washing is performed by a pressure filter and is fast and water-saving, the sewage treatment cost can be effectively lowered, and the production cycle can be shortened; and the content of silicon carbide after purification exceeds 98%.

Description

A kind of silicon carbide filter cake alkali cleaning method of purification

Technical field

The present invention relates to the solid-liquid separation technique field of waste mortar, especially a kind of from silicon single crystal section waste mortar after solid-liquid separation, the silicon carbide filter cake that obtains, the method for the silicon carbide of purifying again.

Background technology

Silicon carbide (micro powder grade) forms silicon carbide suspension mortar with after the polyoxyethylene glycol cutting fluid was mixed by 5: 5, and photovoltaic product list (many) crystal silicon rod is cut, and after cutting, this mortar can be recycled, and avoids influencing environment.Mainly contain silicon carbide, polyoxyethylene glycol cutting fluid, silica flour etc. in the waste mortar, after this waste mortar process pressure filter solid-liquid separation, obtain silicon carbide filter cake (mainly containing silicon carbide, silica flour, carbon etc.).

The general carborundum content 80% of silicon carbide filter cake, silica flour content 15%, carbon content 3.5%, other impurity 1.5%.In purification process, need adding sodium hydroxide and silica flour to react, thereby removal silica flour, traditional technology is that the silicon carbide filter cake is dropped in the water, add sodium hydrate solid more in batches and react, during produce a large amount of gas, temperature is up to 120 ℃, boiling state, material spray from reactor or reaction tank easily, cause loss of material; Adding alkali number is several times of the silica flour amount, thereby causes production cost to rise, and back road soda water consumption is big, the cost of sewage disposal height.

Summary of the invention

The purpose of this invention is to provide a kind of silicon carbide filter cake alkali cleaning method of purification, be fit to industrial scale production.It is raw material that the present invention adopts with silicon carbide filter cake, sodium hydroxide, silicon carbide filter cake and sodium hydroxide are dissolved in respectively in the water, and silicon carbide filter cake suspension splashes into and removes pasc reaction in the alkaline solution, adds water again and carries out press filtration, be neutral until pH, obtain wet carbonization silicon crude product.

The objective of the invention is by realizing by the following technical solutions:

Silicon carbide filter cake alkali cleaning method of purification, the step of described method is as follows:

(1) the silicon carbide filter cake was mixed with 1: 1 by weight with water, stir; Sodium hydroxide is mixed with 1: 2 with water, stir;

(2) silicon carbide filter cake suspension is slowly injected buck, carry out alkali reaction;

(3) reacted silicon carbide suspension was added water by 1: 1, carry out 3-4 press filtration respectively and obtain the wet product of silicon carbide.

As the preferred technical solution of the present invention, described initial reaction temperature is 60 ℃, and temperature of reaction is 90 ℃.

As the preferred technical solution of the present invention, the wet product of described silicon carbide and quality be than 1: 1, clean to pH be 7-8, carborundum content is more than 98%.

The invention has the beneficial effects as follows: with respect to prior art, the present invention adopts titration formula reaction method to remove the silica flour alkali reaction, and silicon carbide suspension is splashed in the buck, and temperature of reaction is controlled all the time at 90 ℃, and gas evenly produces, and can not cause boiling state; Significantly reduce the consumption of alkali, water, alkali and silica flour feed intake at 2: 1, can fully react, and save production cost; Back road soda adopts pressure filter, and quick, water-saving can effectively reduce cost of sewage disposal, shortens the production cycle; The carborundum content of the present invention after purifying reaches more than 98%.

Embodiment

The method that the alkali cleaning of silicon carbide filter cake is purified adopts titration formula silica removal alkali reaction, keeps 90 ℃ of temperature of reaction, and alkali and silica flour fully react; Adopt press filtration to carry out cleaning sic, significantly reduce the consumption of alkali, water, shorten the production cycle, reduce environmental pollution.

1, the batching that feeds intake

In the 2000L reactor, add 1000kg water and 1000kg silicon carbide filter cake respectively successively, open and stir, be dissolved in fully in the water until the silicon carbide filter cake, form silicon carbide filter cake suspension.In the retort of 6000L strap clamp cover, add 300kg sodium hydroxide and 600kg water, during exothermic dissolution can take place, water temperature is opened to stir and is also opened the jacket steam heating about 45 ℃, to water temperature at 60 ± 2 ℃, the steam off heating keeps stirring.

2, silica removal alkali reaction

2000L reactor bottom valve is slowly opened, silicon carbide filter cake suspension slowly injects the 6000L reactor, silica flour and alkali react, when temperature rises to 90 ℃ from 60 ℃, turn down 2000L reactor bottom valve, open the water coolant of 6000L reactor, keeping the still interior reaction temperature is 90 ± 2 ℃, about 3-4 hour, silicon carbide filter cake suspension dropwised, and prolonged 1 hour still internal reaction time.

3, press filtration soda

After the prolongation reaction finishes in the 6000L reactor, add 2500kg water, stir, pH value of water solution is about 12, this silicon carbide suspension squeezed into carry out press filtration in the plate-and-frame filter press, get wet carbonization silicon crude product 1050kg, again this 1050kg wet carbonization silicon crude product is dropped in the 1050kg water and stir, press filtration again, this operation is 1-2 time successively, detects between the pH value 7-8 until the silicon carbide crude product, finally obtaining wet carbonization silicon crude product is 960kg, moisture 20% after testing, and carborundum content is 98.2% (amounting to dry product calculates), yield 94.27% (amounting to pure silicon carbide calculates).

Claims

1. silicon carbide filter cake alkali cleaning method of purification is characterized in that the step of described method is as follows:

2. silicon carbide filter cake alkali cleaning method of purification according to claim 1, it is characterized in that: described initial reaction temperature is 60 ℃, temperature of reaction is 90 ℃.

3. silicon carbide filter cake alkali cleaning method of purification according to claim 1 is characterized in that: the wet product of described silicon carbide and quality be than 1: 1, clean to pH be 7-8, carborundum content is more than 98%.