Precipitated Silica Production
Silica is not a new commodity inthe plastics market. Its usage as extenders and reinforcing fillers, aspozzolanic material and as glass microspheres for specific engineeringapplications are well known in the market. Because of its high silica andlignin content, rice husk is tough, woody and abrasive in nature with lownutritive properties and resistance to weathering. With growing environmentalconcern, open burning has been outlawed in many major rice-producing countries. 18% of the rice husk can be retrieved asash after the gasification process. Silica content in ash is almost 90% and therate of recovery of precipitated silica is 90-95% from the rice husk ash if theconversion efficiency is more than 70%. Rice hull ash (RHA) contains over 60%of silica which can be an economically viable raw material for the productionof silica based products.
Silica generation is a separateindependent process not dependent on electricity generation, although the inputash is dependent on gasification process. Provision will be taken in the designso that external ash is used also as input thus increase silica production.
Liquid sodium silicate isprocessed with acid and filtered. The filter separates a diluted sodium sulfate(Glauber’s salt solution) and the wet silica product. The salt solution can beevaporated or fed to a reverse osmosis and solid salt is produced as valuableby-product. The wet filter cake is finally washed and fed to the drying unit.With special dryers a precipitated silica product with about 8% water contentis produced. The precipitated amorphous silica powder is screened and stored instorage silos. For distribution of silica products packaging in bags of varioussizes is executed in the packing unit.
Uses of Precipitated Silica
• Rubber industry – as areinforcing agent
• Cosmetics
• Tooth pastes – as a cleansingagent
• Food industry – as ananti-caking agent.
• Paints – as a filler
The distinguishing feature of the growth of precipitated silica industryin India is that it has classifiably flourished in the small scale sector.Readily available new materials low capital investment & high rates ofreturn offer a distinct advantage to the small scale manufacturers to ventureinto this field. There is a very good scope in this sector.
Few Indian Major Players are as under:
Gujrat Multi Gas BaseChemicals Private Limited
Gujarat Multi Gas Base Chemicals PrivateLimited,
Mumbai ManswillChemicals Private Limited
Wellink ChemicalIndustrial Company Limited,
Nanping InsilcoLimited
Famous Minerals andChemicals Private Limited
Gujarat Silicon Pvt.Ltd.
