COCONUT

Coconut Shell and Shell Products

Coconut shell comprises of 12 % of the weight of coconut. In India, coconut shells are mainly used for fuel and a very small quantity is used for handicrafts. Coconut shells are commercially utilized mainly in Sri Lanka, the Philippines and Indonesia.

1. Shell Charcoal:

Shell charcoal is one of the purest form of charcoal as hard wood charcoal and coal have much higher ash content.

Coconut shell charcoal are products obtained after carbonizing coconut shell with a limited supply of air. (This is the raw material for the manufacture of activated carbon).The yield varies from 25-33% of the mass of raw shell. In India, about 50,000 shell are required to yield one ton of charcoal. While in Sri Lanka and Philippines only 20,000 raw whole shells are required to yield as the coconut are big in size. The quality of charcoal depends upon several factors such as maturity of the shell, presence of fibre , kernel of the shell and carbonizing procedure. Now several modern methods are in vogue for the production of charcoal. In the modern waste heat recovery unit, the heat generated by the burning of coconut shells is used for drying copra and shell charcoal is obtained as by-product.

A good quality charcoal is uniformly black in colour and free from un burn pieces. According to Sri Lankan Standard 571 are: Moisture - 10% max; Volatile matter on dry basis - 20% max; Ash on dry basis - 2% max and Fixed carbon on dry basis - 79% min.

Shell charcoal are mainly used for the manufacture of activated carbon. Other important uses of shell charcoal include reductant in smelting furnaces and for carbon electrodes in dry cells. Shell charcoal is one of the purest forms of charcoal, as hardwood charcoal and coal have much higher ash contents.

2. Activated carbon:

Activated carbon can be made from a wide range of source materials, such as coal, coconut shells, wood, peat, or bone. The material is often charred, then activated chemically or in a high temperature steam environment to produce an extensive network of pores. These pores provide sites for the adsorption of chemical contaminants in gases or liquids. Coconut shell carbons have several advantages over carbons made from other materials. Coconut shell-based activated carbons have a high density, high purity, and are virtually dust-free, since they are harder and more resistant to attrition. Also, the pore structure is very uniform, with the majority of pores falling in the micropore range (5-10 Angstroms), particularly effective for air and water purification applications.

There are two types of activated carbons – granular (made of shell charcoal) and powdered (made of wood charcoal).

Activated carbon manufactured from coconut shell is considered superior to those obtained from other sources mainly because of small macropore structure which renders it more effective for the adsorption of gas/vapour and for the removal of colour and odour of compounds.

Steam activation and chemical activation are the two commonly used processes for the manufacture of activated carbon. Activared carbon from coconut shell is manufactured mainly in horizontal kilns. However coconut shell based activated carbon units are adopting the steam activation process to produce good quality activated carbon. Due to their incredibly large surface area (up to 1200 square meters per gram), activated and impregnated activated carbons are widely popular for many diverse applications. Examples of applications of shell charcoal activated carbon are military and industrial gas masks, solvent recovery plant in industry, recovery of petroleum gas, purifying recycled air in central air-conditioning, air pollution control, cigarette filters, tertiary treatment of water used in the brewery, liquor and pharmaceutical industry for the removal of flavours and odours, dechlorination of municipal water, and gold dust recovery. The activated carbon is extensively used in the refining and bleaching of vegetable oils and chemical solutions, water purification, recovery of solvents and other vapours, recovery of gold, in gas masks for protection against toxic gases, in filters for providing adequate protection against war gases etc.

3. Shell powder:

Coconut Shell Powder is derived from matured coconut shells by using a pulverizer. Coconut shells are cleaned and broken manually into small pieces and then fed into pulveriser. The shell flour is graded into particle sizes BSS-100+200, BSS-200+300, and BSS-300 (dust), using a cyclone separator. Recovery is around 90%. Coconut shell flour is extensively used as a compound filler for synthetic resin glues. Used with specialized surface finishing liquid products (as an absorbent), mastic adhesives, resin casting and bituminous products. It is also used as a filler and extender for phenolic thermosetting plastics such as Bakelite to reduce “ageing”. In a Granular form it is used as a Lost Circulation Material in Oil Well Drilling. Used as a mild abrasive in shot blasting of delicate objects and of historic buildings.In Asia, it is widely used for the manufacture of insect repellent in the form of mosquito coils.