Rice Husk Ash

Rice milling industry generates a lot of rice husk during milling of paddy which comes from the fields. This rice husk is mostly used as a fuel in the boilers for processing of paddy. Rice husk is also used as a fuel for power generation. Rice husk ash (RHA) is about 25% by weight of rice husk when burnt in boilers.  It is estimated that about 70 million tones of RHA is produced annually worldwide. This RHA is a great environment threat causing damage to the land and the surrounding area in which it is dumped. 

During milling of paddy about 78 % of weight is received as rice , broken rice and bran .Rest 22 % of the weight of paddy is received as husk . This husk is used as fuel in the rice mills to generate steam for the parboiling process . This husk contains about 75 % organic volatile matter and the balance 25 % of the weight of this husk is converted into ash during the firing process , is known as rice husk ash ( RHA ). This RHA in turn contains around 85 % - 90 % amorphous silica.

So for every 1000 kgs of paddy milled , about 220 kg ( 22 % ) of husk is produced , and when this husk is burnt in the boilers , about 55 kg ( 25 % ) of RHA is generated. 

Preparation of Rice Husk Ash (RHA)

Acid treatment is one of the most useful routes used to remove the lignin, wax and oils covering the external surface of the fiber cell wall of natural fibers. Rice husk ash is a solid obtained after burning of rice husk and was washed with distilled water, dried in an oven at about 60°C for 2 h. Then bleached with conc. HCl to remove the dirt and other contaminants present in it and subsequently washed with water till the pH become neutral, then dried in oven at 60°C for 4 h. Then it was heated at 500°C for 5 h in a muffle furnace, to obtain rice husk ash.

Application of Rice Husk Ash

RHA is a carbon neutral green product. Lots of ways are being thought of for disposing them by making commercial use of this RHA. RHA is a good super-pozzolan . This super-pozzolan can be used in a big way to make special concrete mixes . There is a growing demand for fine amorphous silica in the production of special cement and concrete mixes ,high performance concrete , high strength, low permeability concrete, for use in bridges, marine environments , nuclear power plants etc. This market is currently filled by silica fume or micro silica , being imported from Norway, China and also from Burma . Due to limited supply of silica fumes in India and the demand being high the price of silica fume has risen to as much as US$ 500 / ton in India .

From RHA we manufacture organic micro-silica / amorphous silica, with silica content of above 89%, in very small particle size of less than 35 microns – Silpozz for application in High Performance Concrete.

Other uses of Rice Husk Ash 

This product can be used in a variety of applications like: 

• green concrete
• high performance concrete
• refractory 
• ceramic glaze
• insulator
• roofing shingles 
• waterproofing chemicals
• oil spill absorbent
• speciality paints
• flame retardants 
• carrier for pesticides
• insecticides and bio fertilizers etc

Specifications:

Rice Husk Ash (Standard specification)

Silica content more than 85%

Carbon Content less than 5%

Moisture less than 1%