Silicate production caustic soda

With Silicon.—If a solution of caustic soda is brought to contact with elemental silicon, chemical reaction ikes place, with the production of sodium silicate and y drogen. The following equation was supposed to .present the reaction —... 

An intimate mixture of ferro-silicon and powdered caustic soda or lime is packed in strong cylinders communicating with a high pressure storage. By means of a fuse the temperature is locally raised so that chemical reaction takes place, with the production of hydrogen and sodium and calcium silicates. 

Al203, are dissolved in 2,300 ml of water, to which a solution comprising 272 g of caustic soda with 800 ml of water, is slowly added with stirring. Thereafter, a solution comprising 414 g of sodium silicate (Na20, 9%, Si02, 29%) with 100 ml of water is added, the mixture is heated and is stirred for five hours, while keeping the temperature at 60°C. When the reaction mixture becomes neutral it is allowed to cool and to stand, the supernatant fluid is withdrawn and the white gel-like precipitate is washed by decantation to remove the impurities and dried at 105°-110°C and 350 g of white powder of fine particle size is obtained as the final product (almasilate). 

Some of the major products that come to mind most naturally in this category are sulfuric acid, caustic soda, soda ash, chlorine, salt cake, phosphates, and silicates. 

The ore is first treated with caustic soda under pressure. The aluminium largely dissolves as the aluminate, the iron oxide is insoluble and the silica also remains in the form of a sodium aluminium silicate, which leads to a loss of aluminium. Hence the best bauxites are those low in silica. After filtration, the hydrated aluminium oxide is reprecipitated by seeding and the caustic soda solution may be re-used. The alumina is washed and then heated at 1200°C to remove water. The final step in the production of aluminium metal has to be electrolytic since the reduction of alumina with carbon is only possible at very high temperatures and the reverse reaction occurs on cooling. Moreover, because of the chemistry of aluminium, the electrolysis medium cannot be water in fact almost all commercial production of aluminium during the last ninety years has used an electrolysis in molten cryolite (Na3AlF5). 

Solutions of intermediate ratios may be adjusted by blending standard liquors of ratios 2 and 3, respectively (see Figure 22.3). Caustic soda can be added to produce more alkaline sodium sUicale solutions and silica to obtain more siliceous types [1,5,6,13,18,21]. The concentration in the filtered silicate solution may be increased to the desired density by passing it through evaporators under reduced pressure. Water may be added to achieve products of a lower solids level [1,5,6,11]. 

The caustic soda, which is needed for both the hydrothermal production of sodium silicate solution and for the production of sodium aluminate is manufactured by the extraction of sodium chloride [24-27,142] and subsequent electrolysis of sodium chloride brine to yield caustic soda solution [20,52-61,120,142]. 

A wide variety of snrfactants including anionic and nonionic are widely used as shown in Table 10.45. Bnilder salts, snch as phosphates, EDTA-Na4, soda ash, and citrates, are also used. Certain special ingredients snch as ammonia or pine oil are product specific and are widely nsed. Alkaline sonrces are added to the formnlations, and they are available from caustic alkali, alkanolamines, silicates, and phosphates. Many hard surface cleaners contain some solvents typically they are alcohol, glycol ethers, or abrasive materials are preferable. Calcium carbonate, laponite clay, silica (Si02), alnmina (Al Oj), and titania (Ti02) are widely used as abrasive agents. 

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