Precipitated Silica from Rice Husk Ash

Silica is the major constituent of the rice husk ash. So precipitated silica production will not only provide value addition but also solve the problem of large amount of ash disposal generated from gasification process. 

Precipitated Silica Production

Silica is not a new commodity in the plastics market. Its usage as extenders and reinforcing fillers, as pozzolanic material and as glass microspheres for specific engineering applications are well known in the market. Because of its high silica and lignin content, rice husk is tough, woody and abrasive in nature with low nutritive properties and resistance to weathering. With growing environmental concern, open burning has been outlawed in many major rice-producing countries. 18% of the rice husk can be retrieved as ash after the gasification process. Silica content in ash is almost 90% and the rate of recovery of precipitated silica is 90-95% from the rice husk ash if the conversion efficiency is more than 70%. Rice hull ash (RHA) contains over 60% of silica which can be an economically viable raw material for the production of silica based products.

Uses of Precipitated Silica
• Rubber industry – as a reinforcing agent
• Cosmetics
• Tooth pastes – as a cleansing agent
• Food industry – as an anti-caking agent.
• Paints – as a filler