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What is white carbon black?
News source:    Reads:14549    AddTime:2009/1/9 16:25:49    Collects this page

White carbon Black is a white powder X-ray amorphous white carbon blackte and white carbon black products, collectively, mainly refers to the white carbon black precipitation, fumed white carbon black, white carbon black gel and ultra-fine aerogels, including synthetic powder Aluminum and calcium white carbon blackte, and so on. White carbon black is a porous material, its composition can be used SiO2 . nH2O said nH2O which is in the form of surface hydroxyl groups. Can be dissolved in hydrofluoric acid and caustic alkali, insoluble in water, solvents and acids (hydrofluoric acid). High temperature, non-combustible, tasteless, odorless, has a very good electrical insulation.
       By white carbon black production methods can be divided into precipitated white carbon black and fumed white carbon black. Fumed white carbon black for normal flocculent translucent white amorphous solid colloidal nanoparticles (particle size less than 100nm), non-toxic, there are huge surface area (100 ~ 400m2 / g) (using the F-Sorb 2400 surface area Instrument testing method BET). Fumed white carbon black is all the nano-white carbon black, the product purity of up to 99%, up to size 10 ~ 20nm, but the complexity of the preparation process, expensive; precipitated white carbon black is divided into the traditional precipitated white carbon black and special precipitation White carbon black, the former refers to the sulfuric acid, hydrochloric acid, CO2 and water glass as the basic raw material production of silicon dioxide, which refers to the use of high-gravity technology, sol - gel, chemical crystal method, the crystallization of the second or RP Microemulsion micelles and other special methods of production silicon dioxide. The white carbon black surface area is also very important, the white carbon black surface area of research and data in the report, only detected by BET using the results are real and reliable, at home and abroad because of the development of specific surface area measured by the standard tests are based on BET Method-based. (GB.T 19587-2004) - gas adsorption BET principle of determination of specific surface area of solid material. Determination of surface area-specific analysis of the surface area tester, is a more mature domestic dynamics of nitrogen absorption, most of the existing China-made equipment can also direct comparison of the law, F-Sorb 2400 surface area analyzer is able to achieve real BET method of detection equipment (both direct contrast) and, more importantly, F-Sorb 2400 surface area analyzer is so far the only fully automated intelligent than the surface area of detection equipment, test results and consistency of the international high Stability is also very good at the same time to reduce human error and improve the accuracy of test results.
        Precipitated white carbon black mainly for natural rubber and synthetic rubber reinforcing agent, toothpaste, etc. friction. Gas white carbon black mainly for the silicone rubber reinforcement agent, coating resins and unsaturated thickener, ultra-fine white carbon black aerogels and gel coating is mainly for extinction agent, thickening agent, plastic film openings, etc..
2, production methods
      Preparation of white carbon black traditional method is to use sodium white carbon blackte, silicon tetrachloride and do TEOS silicon source, with the exception of sodium white carbon blackte, other costs are high. A new method using low-cost non-metallic mining as a source of silicon, greatly reducing the cost of production of white carbon black.
2.1 Traditional methods
(1) Gas Act
      For the main chemical vapor deposition (CAV) method, also known as pyrolysis, dry or burning them. General raw materials for its silicon tetrachloride, and oxygen (or air) and hydrogen, from a high temperature reaction. Reaction:
SiCl4 + 2H2 + O2-> SiO2 +4 HCl
      After air and pressurized hydrogen gas, respectively, separation, dehydration cool, dry white carbon black, after the dust filter into the synthesis furnace hydrolysis. Silicon tetrachloride raw materials will be sent to the distillation after distillation, in the evaporator in heat evaporation, and dry, filtered air as a carrier to the synthesis furnace hydrolysis. Silicon tetrachloride at a high temperature gasification (flame temperature 1000 ~ 1800 ℃), with a certain amount of hydrogen and oxygen (or air) at about 1800 ℃ high temperature gas hydrolysis; generated at this time of fumed white carbon black particles Very fine, gas and aerosol form, not easy to capture, it gathered in its first-in gathered into larger particles, and then collected by the cyclone, and then off into the furnace acid, nitrogen dioxide gas to wash the air blowing PH value of between 4 to 6 is finished.
      Degussa (Degussa) and the United States, Cabot Corporation (Cabot) the company's gas production of the world's leading technology. Their large-scale production, a high degree of automation products, low-cost brands (especially in the field of application of the special features of the product-specific brand), good quality and distribution, such as surface area, low water content. China's Shenyang Chemical Industry Co., Ltd. and Shanghai Chlor-Alkali Chemical Co., Ltd. also gas production, but the scale of production, production technology, automation products and brands, and so on far less than foreign companies. Guangzhou Science and Technology Ji Sheng Industrial Co., Ltd. will present domestic production is the largest, most brand-wide, the most technologically advanced silicon dioxide gas suppliers, fumed white carbon black is a national standard GB20020-2005 units in charge of drafting.
(2) precipitation
       Sodium white carbon blackte, also known as acid precipitation method, using water glass solution with the acid reaction, sedimentation, filtration, washing, drying and calcining be white carbon black. Reaction:
Na2SiO3 + 2H + -> white carbon black + 2Na + + H20
Most of the domestic manufacturing enterprises to adopt precipitation.
2.2 A new method
       A new method to the main non-metallic mineral and its extension to the source of silicon, using white carbon black prepared by precipitation. The technology is the key to the crystalline white carbon black and white carbon blackte into amorphous silicon dioxide. The main raw materials are wollastonite, opal, halloysite rock, olivine, a snake mosquito stone, kaolin, hard kaolin, coal, fly ash, and so on.
This report focuses on hard-to kaolin, or kaolin, coal fly ash or raw materials for the preparation of white carbon black technology.
(1), kaolin, or hard kaolin as raw materials
       Kaolin first or kaolin hard smash to 50 to 60 head, and then 500 ~ 600 ℃ high temperature roasting 2 hours, and then roast the concentration of land and 30% of the industry by hydrochloric acid 1:2.5 (weight) ingredients, in about 90 ℃ Acid leaching 7 hours, and, filtration, washing, drying be white carbon black, the quality of products in line with the standard GB10507-89; at the same time be highly efficient water purification agent chloride. Acid leaching and calcination reaction is as follows:
Roasting: Al2O3 • 2Si02 • 2H20 -> Al2O3 • 2Si02 + 2H20
Acid leaching: Al2O3 • 2Si02 + 6HCl + 9H20 -> 2AlCl3 • 6H20 + 2SiO2
(2) to coal fly ash as raw materials or
     First coal fly ash or crush size to less than 120 head, and then two steps:
The first step in the production of sodium white carbon blackte: to smash the coal fly ash or soda ash and 1:50-to-weight ratio by evenly mixed, with high-temperature melting Ye (1400 ~ 1500 ℃, 1 hour), water extraction solution Baptist (100 ℃ over , 4 to 5 hours), to filter impurities, concentrated filtrate to 45 ~ 46 degrees Baume is to be sodium white carbon blackte.
     The second step white carbon black production: first match sodium white carbon blackte solution (module for the 2.4 ~ 3.6, SiO2 content of 4 ~ 10%), and then 5 to 20% of the sulfuric acid in acid leaching (28 ~ 32 ℃ , 8 to 16 hours) and then heated to 80 ℃, mixing, adjusting PH value of 5 to 7, ripening 20 minutes, and then filtered by washing, drying, sorting, to be white carbon black. It white carbon black for the activity of high purity.
3, production capacity / output
     To the domestic precipitated white carbon black-based, in 1958 precipitated white carbon black to achieve the industrialized production, but production of small, slow development. 1987 also produced only 2687 tons; 10,000 tons in 1990 to achieve a breakthrough 10,600 tons; growth in 1994 to 28,100 tons, representing an increase of 9.4 times in 1987; in 1997 China's white carbon black production reached 80,000 tons or so; rise in 2004 To nearly 300,000 tons. Over the last decade shows that China's output of carbon black is white by leaps and bounds.
     Domestic production of white carbon black broader distribution, a total of more than a dozen provinces and municipalities production, production of which is larger, Fujian, Shandong, Jiangsu, Jiangxi Province. At present, there are dozens of white carbon black manufacturing enterprises in the total capacity of 400,000 tons / year or so. Among the larger precipitated white carbon black manufacturing enterprises have Kerry in conjunction Fujian Nanping Chemical Co., Ltd., Shanghai Fine Chemical Co., Ltd. Sum Nine, Zhuzhou Xinglong Chemical Industry Co., Ltd., Rhodia White carbon black (Qingdao) Co., Ltd., Wuxi Hang Heng white charcoal And limited liability company, Xin Xu Tengzhou Chemical Co., Ltd. and so on. Fumed white carbon black, the Guangzhou Science and Technology Ji Sheng Industrial Co., Ltd. will be able to reach production of 6,000 tons / year, is the largest supplier of fumed white carbon black.
      As the white carbon black optimistic about the prospects for the market, some domestic enterprises currently under construction or planned construction projects white carbon black, expansion, but also new. If the nine-chen of the Shanghai Fine Chemical Co., Ltd., Puyang City, Guang-pu petrochemical companies, such as Hubei Success Group.
      China in 2010 is expected to white carbon black production capacity is expected to exceed 1,000,000 tons / year mark.

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