Extraction Of Silica From Rice Husk tank 0.4-30t/h Capacity

Extraction of Silica from Rice Husk

The plants belonging to graminae family, namely, rice, wheat, barley, oats, maize are the main sources of biogenic the roots as dissolved monosilicic acid, Si(OH)4& precipitated within around cells as hydrated deposits.The monosilicic and moves by evaporation of polymerized to force a cellulose silica membrane. It has been formal that silica is highly concentrated in the inner and outermost surfaces of the epidermal twice. As a result, rice husks are relatively friable, brittle and abrasive. The term white ash refers to residue obtained from complete combustion of rice husk. It if chiefly composed of silica (86-97%). This silica has following structure, in which the atom is bonded to four surrounding O atoms by Si-O-Si bonds. Above fig. shows that each Si atom is surrounded by four O atoms and O atom serves as a neighbor to two Si atoms there by leading to a condensation product with a formula SiO2.Silica occurs in nature mainly in three crystalline fours namely quartz (hexagonal), cristobolite (white) and tridymite (hexagonal) and also in amorphous form like opal and silica in rice husk being of bioquenic origin is essentially of amorphous nature. But it can be connected into any of above three crystalline forms by heat treatment at different temperature.

The precipitated silica market can be broadly classified as rubber grade and non- rubber grade. The total size of the silica market in India is about 16000 tones.  Out of this rubber grade silica market is 11000 tones and non-rubber grade market is 5000 tones. Tires, rice roller mills, adhesive, toothpastes, free-flowing salt and certain food products are major users of silica in the country. The market is currently growing at the rate of 8% per annum. Some uses are as listed below

 Reinforcement of elastomeric products like shoe soles.  Reinforcement of silicone rubber.

 Reinforcing material in tires.

 In sheathing compounds for cables.

 Constituent of adhesives in for bonding of unvulcanized rubber to textiles or steel tire cord.

 In thermoplastics used to act as anti-blocking agents and to prevent plate out effects in films and film production.

 To improve mechanical properties of PVC flooring.

 As carrier silica for materials and as free flow agents for powder formulation, particularly of hygroscopic and adhesive substances.

 As adsorbent.

 In toothpaste to control rheological properties and as a cleansing agent.

 Hydrophobic precipitated silica is used in mineral oil and silicone oil antifoaming effect.

 Purification and stabilization of beer.

 Analysis of blood.

 Cosmetics.

 Food industry as an anti-caking agent.

 Specially prepared silica gels from silica are used for making thermal insulation material.

 As a dehumidifying agent for air and other gases.

 As a filtering agent to clarify of juices.