Agriculture Reference
In-Depth Information
However, briquettes may be better suited for low-end applications. At present some
briquettes are made from different materials, mostly wastes. In Asian and Far Eastern
countries, briquettes made from rice hulls are very popular. China and Thailand are
offering to produce briquettes having dimensions of 20-40 cm (length) and 5-7 cm
(diameter) and these densified briquettes will have a heat content of 3,000-4,000
kcal/kg. Rice hulls in the densified state are difficult to ignite, so manufacturers may
incorporate an igniting promoter in the mix. There will be a market for the ash that
results from such procedures.
5.4.11 Rice Hull Ash
The ash produced after hulls have been burnt is high in silica. The list below shows
some of the possibilities in which this material can be applied but a word of caution
is called for. Irrespective of the process that results in the production of ash or the
method employed directly to produce rice hull ash, a very fine 'dust' will be emitted
into the air in addition to the deposits of ash at the bottom of a device. In general, this
dust will emerge through a chimney and, if not grounded through a curved chimney,
will cause air pollution and create problems for any buildings close by:
• Aggregate and iller for the production of concrete and board
• Economical substitute for micro-silica/silica fumes
• Absorbents for oil and chemical spills
• Soil ameliorants
• Source of silicone
• An insulation powder in steel mills
• Repellents in the form of 'vinegar-tar'
• Release agent in the ceramics industry
• Insulation material for homes and refrigerants
5.4.12 Case in Point
I present a case in point for the beneit of readers of this topic for the possibility of
using rice hulls in the natural state as fuel for steam boilers on an industrial scale.
 
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