Rice husk (RH) is the outer covering of the rice grain and is obtained during the milling process. Instead of wasting rice husk it can be utilized in many beneficial ways as a useful by-product.

1. Recycling of Rice Husk into a Locally made Water-
Resistant Particle Board

2. INTRODUCTION
 Rice is a major food crop in
many regions of the world.
 The worldwide production
area for rice is about 150
million hectares, while the
annual production is about
590 million tonnes.
 The milling of paddy rice has
nearly a 70% yield of rice
as its major product.
Percentage of crop area
under various crops

3.  Unconsumed portions of the
rice produced include rice
husk (20%), rice bran (8%)
and rice germ (2%).
 Rice husk (RH) is the outer
covering of the rice grain and
is obtained during the milling
process.

4. Spikelet
Paddy Rice Pedicel
Harvesting
Harvest
Dehusk
HuskBrown Rice
Polish
White Rice Bran &
Embryo
RICE PROCESSING

5. Composition
of Rice
Husk
The main
components in RH
are:
 Silica
 Cellulose
 Lignin

6. Potential uses of rice husk
 Production of
animal feeds
 Bedding materials
 Soil conditioner
 Fertilizer
 Bio-fuel
 Carbon
 Refractory
insulating
materials
 Paper board
manufacturing

7. In developed countries, like the
US, where rice mills are
operating on a large scale are
concentrated, rice husk have
been used to generate energy
for the rice mills themselves.

8.  As a renewable material, the use of RH can
eliminate waste disposal and support
environmental protection.
 Rice husk particleboard is being considered
as a potential substitute for wood and wood-
based board products.
 Particleboard is cheaper, denser and more
uniform than conventional wood and
plywood and is substituted for them when
appearance and strength are less important
than cost.

9. RH In The
Construction
Industry
High availability
Low bulk density
(90-150kg/m3)
Toughness
Abrasive in
nature
Resistance to
weathering
Unique
composition.

10. Rice Husk
Boards
Various types of
board can be
produced from rice
husk. These by-
products include:
 Particleboards
 Insulation boards
 Ceiling boards.

11. Traditional Approach for
Manufacturing Rice Husk
Particleboards
Producing particleboard panels requires:
 Combining wood particles (such as wood chips)
 Saw dust
 Rice husks
 Suitable binders
 Applying pressure in the presence or absence of heat
Requires little energy input to prepare the husk for board manufacture.

12. Process Involved in the
Production of RH
Particleboards
ResinRice Husk
Mixer
Mold ProductHydraulic Press

13. Traditional Approach for
Manufacturing Rice Husk
Insulation Boards
Insulation boards is similar to that of particleboards.
 Boards are generally made in different thicknesses, ranging
from 4mm to 25mm.
 Their densities range from 500kg/m3 to 900kg/m3 for medium-
density boards.
 For low-density RH boards, the density is less than 500kg/m3.

14. Classical Approach for
Manufacturing Rice Husk
Ceiling Boards
 It is produced by combing RH and sawdust.
 Slurry is produced by heating RH with caustic soda.
 This slurry is then washed with water and beaten into pulp, to
which sawdust (filler) and glue is added.
 The slurry is formed into sheets in the press and sun dried.
 Higher tensile strength (32N/m2) compared to only RH boards
(22N/m2) and are comparable to commercial ceiling boards
(23.5N/m2).

15. Process Flow Diagram for
Producing RH Ceiling Board
Rice
Husk
Water
Binder
Saw
Dust
Caustic
Soda
Digester
Beater
Press Drying Product

16. The Role of Adhesives in
Particle Board Production
 Some adhesives produce extremely strong bonds.
 Adhesives should be flexible and soft to respond to the dynamic
effects of swelling and shrinkage, yet impart the required
strength.
 Commonly used synthetic adhesives: phenol-formaldehyde and
urea formaldehyde.
 Natural adhesives: soybean protein and starch.

17. Modified
Starch
Adhesive
Particleboards
Mixture of modified starch (MS)
and wood fiber (WF) together
with raw RH made available
from a rice milling factory.
WF is made up of shredded
paper boxes disposed from
packaging.
These RH particleboards are
produced by placing the
mixture on a flat surface mold
and drying it under the sun.

18. RH particleboards produced with
100% WF, 50% WF plus 50% MS
and 100% MS by weight.

19. Advantages of
Rice Husk
Particleboards
Waste agricultural residues can be recycled to
form a useful product.
Inexpensive alternatives to high-end cabinets,
shelves and furniture.
Boards can be painted for decorative finishes.
Boards can be used in building interiors such as
wall or ceiling linings, paneling, partitioning and for
providing insulation in buildings.