SODIUM SILICATE Rotary Furnace Process: The State-Of-The-Art Technology is used to manufacture sodium silicate by fusing pure silica sand with soda ash in rotary furnace at 1300oC, various SiO2 /Na2O ratios are produced. When the molt is cooled down a clear glass of sodium silicate is obtained, which varies from colorless to greenish blue in color is obtained. A premium product with exceptionally pure quality (maximum of 0.3% metal oxides) is produced.

Mean Weight Ratio SiO2 : Na2O SiO2 % Na2O% Main Use 2.1:1.0 66.7 33.3 Detergents 3.3:1.0 76.7 23.3 Paints

By using a steam pressure dissolver with in-line filtration, glass dissolves in exothermic reaction and gives an exceptionally clear solution with a long shelf life. Various grades of solution with ratio ranging from 2.0 to 3.3 combined with density ranging from 1.36 to 1.6 gm/cm3 and a viscosity ranging from 150 to 7500 CP are being currently manufactured.

Uses

SiO2 : Na2O Wt. Ratio

%

Na2O % Wt. Ratio

SiO2 % Wt. Ratio

Density gm/cm3 @20oC

Total Solids Wt. Ratio

%

Viscosity CP

@20oC Detergent 2.0 15 30 1.54 45 600 Detergent 2.0 16.8 34.20 1.60 51 7500 Foundry 2.0 15 30 1.54 45 600 Titanium Dioxide 3.23 8.50 27.50 1.36 36 150 Recycle Paper 3.23 8.50 27.50 1.36 36 150 Oil Well 3.23 8.50 27.50 1.36 36 150 Construction Chemcials

3.20 9.45 30.25 1.40 40 850

Adhesive 3.20 9.45 30.25 1.40 40 850 Hydrothermal Process: Known as the "Wet Process" for the manufacture of silicates directly in solution form, where the silica from san leached out under pressure by concentrated caustic soda solution. This process lends itself to the production of crystalline silicates solution.

VARIOUS APPLICATONS OF SOLUBLE SILICATES Soluble silicates have properties not shared by other alkaline salts which, together with their relatively low cost, have resulted in wide spread use in many industries. Sodium silicate is used in far greater quantities than silicates based on other alkali metals. Potassium silicate is, however, sometimes preferred in applications where its specific advantages outweigh the extra cost. Detergency One of the earliest uses of sodium silicate was to improve the properties of soap and even today household detergents are one of the biggest single applications. Fabric washing powders actually contain 6% - 15% sodium silicate by weight, within the ratio range 2.0 to 2.4. The role of silicates is multi-functional. They act as corrosion inhibitors for metals and ceramics, assist in dispersion of defloculation of soil to prevent its re-desposition, and play an important part in structuring the finished products.

Chemical Industry Precipitated Silica and silica gels are used widely as reinforcing fillers in rubber, as matting agents for surfaces coating and as polishing and structuring agents in toothpastes. They are made using acid salts to neutralize the sodium silicate under carefully controlled conditions. Zeolites, which are crystalline aluminosilicates, are synthesized from sodium silicate and sodium aluminates. They have as their basic structural unit the SiO4 tetrahedral network, with partial replacement of silicon by aluminum. These materials, sometimes referred to as molecular sieves, are used for ion exchange, and as highly selective catalyst absorbents. Apart from its use as a source of silica, sodium silicate often assists in production, or end-use enhancement, of a number of other important industrial chemicals. Titanium dioxide is widely used as the primary specifying pigment in the paint, plastic and paper industries. Its performance is enhanced by silicate treatment to modify its surface characteristics. Foundry Iron, steel and non-ferrous castings are formed in patented sand moulds and cores which are set to shape using a number of binder materials. Sodium silicate is widely used as a binder in the principal setting systems-the silicate-carbon dioxide and self-setting sodium silicate processes. Adhesive Sodium and potassium silicates are practically the only inorganic materials used as adhesives. They are particularly suitable for adhesive application by reason of their low cost, reasonably rapid set and high strength. The production of paper products, particularly tubes and drums where strength is at a premium, provides and extensive field of application and there are many other industries where silicates are employed. Silicate bonded insulation materials such as vermiculite and perlite are completely non-flammable, the refractory nature of the bond being a major advantage. Potassium silicate is sometimes preferred for applications where heat insulation and fire resistance are chief aims, as it has a slightly higher softening/flow point that its sodium counterpart. Water Treatment Alkaline silicate, usually are used in various ways to treat potable or industrial water, partial neutralization of silicate with acids or acid salts produces an anionic sol which is an extremely efficient coagulation aide, for use with aluminum sulphate during normal purification process. Many bore hole water sources contain high source of iron and manganese. Upon aeration or chlorination these will precipitate as red/brown colored hydroxide, either in main pipelines or during use, giving rise to a high level of consumer complaints. The problem can be overcome by adding a few parts per million of a sodium silicate solution during the treatment process prior to aeration or chlorination. Refractory Cement The properties of Alkaline silicates are suitable for production of high temperature cements. The bond is completely inorganic and compatible with the range of refractory fillers normally used. Two types of refractory silicates cements may be produced. One, the so called plastic cement, is prepared by mixing sodium silicate with a filler, which may be clay or a refractory mineral, until the mix has a putty-like consistency. The other type is dry-blended using a powered grade of silicate and then mixed with the appropriate amount of water when required for use. Applications for refractory cement range from bonding or lining industrial furnace walls and chimneys to cement for household fire-back and stove. Choice of silicate is largely dictated by the degree of fluxing required. This increases with the amount of alkali present and is greater for sodium rather than potassium silicate.

Acid Resistant Cement Acid resistant brickwork and tank linings are required in many industrial processes and, while acid resistant bricks are readily available, choice of suitable cements is restricted. Potassium silicate has proved an extremely useful binder for these cements as the action of an acid and potassium silicate produces free silica which is resistant to all acids except hydrofluoric. These cements are formulated in a similar manner to refractory cements, but fillers chosen must also be acid resistant in this case. Mineral Beneficiation Sodium silicate is used in froth flotation to disperse slimes. It also acts as a depressant for siliceous gangue minerals and non-metallic beneficiation processes. A number of minerals, including copper, tin, tungsten, fluorspar and phosphate, utilize silicate in this way. Corrosion Prevention Corrosion is a well-known problem in industries where water systems are involved. Many systems have been developed over the years to protect metal surfaces from the effects of corrosion. One such method which has proved extremely successful is the addition of small quantities of sodium silicate to the water in the system. Sodium silicate is effective in controlling corrosion of many metals and will protect systems containing several different metals where electrolytic corrosion is often a grave problem. The ferrous metals; lead brass, copper, zinc and aluminum are all completely protected and problems caused by such phenomena as plumb-solvency eliminated. Sodium silicate actually reacts with the corrosion products of the metal to form almost insoluble protective film of metal silicate. Soil Consolidation Various techniques are employed to consolidate or seal the ground prior to further operations. In a number of these techniques a siliceous gel is precipitated from a solution of sodium silicate and a suitable reactant. The method by which the gel is prepared varies. One technique is to inject the silicate and a reactant such calcium chloride in separate streams, which react instantly, forming a gel at the point where consolidation is required. Co-reactants suitable for this technique include sodium bicarbonate or aluminates and a range of organic esters. Silicate Paints & Coating Coatings based on soluble silicates are used for various purposes including sealing porous surfaces, heat insulation, binding loose fivers and formulation of certain paints. Although sodium silicate can be used for these applications, it has a tendency to form a unsightly white bloom by interacting with atmospheric carbon dioxide. Potassium silicate is less affected and therefore often preferred. Surface suitable for coating or sealing with silicates include vermiculite, perlite, asbestos and other fibrous or loose-grained minerals and the non-flammability of the silicate is often an important consideration. Alkaline silicates are employed in anti-corrosion paints, particularly those based on zinc, and in situations where heat resistance is vital and can be formulated with aqueous synthetic resin dispersions to reduce cost. Ceramic and Minerals A clay slip, a suspension of clay in water is used to produce ceramic shapes for such applications as the production of bathroom ware. It is important to keep the slip mobile while minimizing water content, which is later removed in the process. To achieve this, a small amount of sodium silicate, usually of silica: Alkali ration 2:1, is added to act as deflocculant or "slip aid" as it is known in the industry. A similar use occurs in the wet process for Portland cement where sodium silicate is used to deflocculate aqueous slurries of chalk and clay, again with the objective of maximizing solids with minimum viscosity.

Roofing Tiles Roofing granules are mineral particles, coated with a coloring pigment prior to incorporation into tiles. The silicates served to bind the coloring pigment to the granule, prior to firing at a high temperature. Sodium silicate is commonly employed but, under certain conditions, potassium silicate may offer advantages by helping to lower the "fixing" temperature. Concrete Treatment New or old concrete surfaces can be improved by treatment with sodium silicate to provide a harder surface, which is far less prone to dusting. The effect is not confined to the surface, as the silicate penetrates into the concrete and reacts with residual free lime to reduce porosity. Welding Rods A welding rod flux coating consists of a variety of mineral and metal powders, bound together with sodium or potassium silicate, extruded onto a supporting wire. Apart from aiding extraction and acting as a binder, the silicate provides a source of alkali for the acr process itself. Reclamation of Mineral Oils During use, mineral oils collect many impurities. For example, carbon, grit, water and various acidic components which impair their properties. The oil can, however, be recovered using chemical processes which rely upon neutralization of acidity and separation of solid impurities into an aqueous phase. Sodium silicate plays an important role in both these mechanisms. Agglomeration Silicates find application as binders in granulating and briquetting fine articles. If the silicate bond is to be water insensitive it is necessary either to heat the bonded product, as when fabricating colored roofing granules, or use it in conjunction with a chemical species which will insolubilise the bond. This happens spontaneously, to some degree, if the material to be bonded contains reactive metal ions of, for example, calcium, aluminum or magnesium. Alternatively, it can be induced by addition of a heavy metal salt. Example of agglomeration applications range from soap and detergent granules to fine pellets or briquettes of phosphate sponge iron and chrome fines.