Method for producing white carbon black and active carbon by using residual rice hull ash after gasification

Abstract

The invention provides a method for producing white carbon black and active carbon by using residual rice hull ash after gasification, which comprises the following steps of: performing alkali solution impregnation, drying and roasting on the residual rice hull ash after the gasification, which serves as a raw material, to obtain a mixture of powdery water glass and carbon powder; adding water into the mixture to dissolve the mixture and boiling the mixture to obtain a water glass solution and the carbon powder; performing the reaction of the water glass solution and soluble alkali metal acid carbonate to obtain silicon dioxide hydrate; filtering the silicon dioxide hydrate; washing and drying a precipitate to obtain the white carbon black; and washing and activating filter residue of the carbon powder to obtain the active carbon, wherein an alkali solution can be recycled. In the method, silicon dioxide in raw materials can well react with alkali, the impregnating absorption performance is good, the uniform permeation is achieved quickly, and the drying link can be switched immediately, so that the large silo capacity for storing impregnated rice hull ash is unnecessary; the anoxic roasting temperature is low, so that the high-temperature corrosion of a furnace body is avoided; the alkali solution can be recycled, so that the loss of chemical raw materials is reduced; the intermediate product powder, which is the mixture of the water glass and the carbon powder, is easy to be separated and filtered; and a prepared white carbon black product is high in purity and strong in activity.

Description

technical field [0001] The invention relates to a manufacturing method of white carbon black and activated carbon, in particular, the remaining rice husk ash after gasification is used as raw material to make water glass and carbon powder, then respectively use carbon powder to make activated carbon, and water glass to make white carbon black. Carbon black and its chemical raw material alkali can be recycled. Background technique [0002] As we all know, white carbon black is a general term for white powdery X-ray amorphous silicic acid and silicate products, mainly referring to precipitated silica, fumed silica, ultrafine silica gel and aerogel. Silica is a porous substance whose composition can be SiO 2 ·nH 2 O indicates that its nH 2 O exists in the form of surface hydroxyl groups. White carbon black is resistant to high temperature, non-combustible, tasteless, odorless, has good electrical insulation, and is easy to crush. Silica is mainly used as a reinforcing agen...

AI Technical Summary

Problems solved by technology

Traditional activated carbon preparation methods mostly use wood, charcoal, etc. as raw materials. Excessive felling of wood will bring about the deterioration of the ecological environment. In order to achieve sustainable development, the country quickly implemented a ban on natural forest logging, resulting in shrinking sources of wood charcoal. Preparation of activated carbon Raw materials are greatly restricted, and prices are also on the rise

In my country, the total rice output is about 200 million tons (accounting for 1 / 3 of the world's total output, ranking first in the world), and a large number of rice husk resources have not been well utilized. In many areas, rice husks are burned, which pollutes The environment is damaged, and rice husk resources are wasted. Under this situation, the new technology of using rice husks to produce activated carbon and white carbon black needs to be improved and perfected urgently

[0003] In order to solve the above problems, the inventor once participated in the design of "a method for producing white carbon black" whose authorized announcement number is CN1037110C. It impregnated grass raw materials such as rice husks with sodium carbonate or potassium carbonate solution, and the impregnated The raw materials are dried with the flue gas of the carbonization furnace, and sent to the reduction carbonization furnace for carbonization treatment or direct combustion to generate a mixture of carbon powder and water glass, which are boiled in hot water at normal pressure and filtered to obtain water glass. Then water glass is reacted with soluble alkali metal acid carbonate to generate hydrated silica, which is filtered, washed and dried to make white carbon black. The filtrate is sodium carbonate solution, and the filtrate sodium carbonate is recovered and recycled. One part is used to impregnate the raw rice husk, and the other part reacts with an appropriate amount of carbon dioxide to form sodium bicarbonate, which is then used to produce white carbon black. The mixture of water glass and carbon powder is dissolved in water, and after the water glass is filtered out, the filter residue is cleaned to contain carbon. The carbon residue with a high amount is the raw material for the production of activated carbon. The advantage of this patent is that the alkali (sodium carbonate) solution is recovered and recycled. This method still has some major disadvantages: (i) the above-mentioned rice husk is impregnated by the alkali solution as a whole , and then drying, this process is not completely reasonable, ① rice husk contains a lot of organic matter, impregnating organic matter with alkaline solution and drying it is ineffective work, which greatly increases the total workload, ② In addition, the characteristics of rice husk are Hydrated silica is interspersed in the organic matter in the form of a network, and the rice husk is very dense, so that the time for the alkali (sodium carbonate or potassium carbonate) solution impregnated with the rice husk to reach uniform penetration is as long as 10-20 hours, so the impregnation of the rice husk requires Large storage capacity. All in all, direct impregnation of rice husks with alkali (sodium carbonate or potassium carbonate) solution is not the best solution and needs to be improved; Or direct combustion, the process of generating carbon powder and water glass mixture” also has defects that need to be improved: ①The impregnated raw materials are dried and then carbonized in a reducing carbonization furnace, which is essentially the process of gasification of organic matter. After the rice husk is dried, a considerable amount of alkali is only attached to the surface of the rice husk, and the impregnated rice husk after drying in the carbonization (organic gasification) process is violently turned over in the gasification gas and adheres to the surface of the rice husk. Alkali on the surface of the surface will fall off and be carried away by the air flow, they have no chance to interact with SiO 2 The reaction produces water glass, and this part of the alkali is lost in essence.

②If it is directly burned, the temperature is often high and it is not easy to control. The consequence is that the carbon powder for preparing activated carbon is insufficiently retained, and at the same time, water glass is easily sintered into a block, which is not conducive to boiling and extraction.

[0004] Also have as publication number CN101177264 " utilize biomass power plant waste to co-produce activated carbon, the method for white carbon black and soda ash ", publication number is CN101391778 " a kind of method that prepares high-purity white carbon black with rice husk ash as raw material ", the publication number is CN101402458 "the method for preparing nanometer silica with rice husk ash", the publication number is CN1039000 "rice husk ash co-production of water glass and activated carbon", the publication number is CN1062513 "using rice husk, rice straw The method for producing water glass", the publication number is CN1229057 " the method for preparing water glass and by-product activated carbon with rice husk ash charcoal ", the publication number is CN101456555 " the method for preparing high modulus water glass and activated carbon with rice husk ash ", the authorized announcement number is CN201254463 "Using rice husk gasification power generation ash to directly produce water glass device", the authorized announcement number is CN13119033 "Highly activated carbon and its preparation method prepared by caustic digestion of rice husk ash", publication number Be CN101264885 " a ​​kind of production method of rice husk ash system high-quality activated carbon ", in the caustic soda boiling method of above-mentioned each patent, caustic soda can not be recycled, when making white carbon black, sodium sulfate, sodium chloride discharge, not environmental protection

[0005] For example, the publication number is CN1090306 "New Process for Preparing Amorphous White Carbon Black and Activated Carbon", the publication number is CN101417798 "A Method for Comprehensive Utilization of Rice Husk Combustion Waste Gas and Waste Residue", and the authorized announcement number is CN1113216 "A Purification Process". SiO 2 The production process of ", adopts the method of boiling rice husk ash with water and alkali, and dissolves the obtained water glass and NaHCO 3 Mix in hot solution, water glass and NaHCO 3 The mixed hot solution of is an unstable system, causes following shortcoming: 1. water glass concentration is too low; 2. water glass and NaHCO 3 The mixed hot solution system is unstable, and the temperature drops slightly when filtering, that is, white carbon black is precipitated, which makes water glass and NaHCO 3 It is very difficult to separate the mixed hot solution from the carbon powder

The reaction temperature of this method is as high as 1300-1400 °C, the furnace body is corroded seriously, the energy consumption is high, and the water glass dissolution process is complicated.

Images