How To Make Fuel Briquettes - Charcoal Dust - Carbonization And Pyrolysis Of Biomass

Today, fuel prices are very high. A briquette is a block of compressed coal dust, charcoal dust, sawdust, wood chips or biomass, and is used as a fuel in stoves and boilers. Smokeless briquettes are made from carbonized or pyrolysed materials. Briquettes made from materials that have not been carbonized are a bit smoky. Carbonization is the conversion of organic substances into carbon in the absence of oxygen as it is done in the making of lump charcoal.

Pyrolysis is defined as thermo-chemical decomposition of organic material under pressure, starting anywhere from 200 °C and especially above 450 °C, in the absence of oxygen. Carbonization is actually extreme pyrolysis which leaves carbon as the residue. Biomass as a renewable energy source is defined as biological material from living, or recently living organisms. In many countries, people are growing crops and keeping animals.

The waste from crops and animals are biomass material that can be used in making fuel briquettes. Agricultural waste materials such as rice husk, coffee husk, coir pith, jute sticks, bagasse (sugarcane waste), groundnut shells, sawdust, mustard stalks, cotton stalks, maize/corn, wheat husk, cattle waste, grass, leaves and cassava can all be used in making fuel briquettes. It is possible to make briquettes from biomass without carbonizing the biomass.

To do this, the green raw materials of the biomass will need to be partially decomposed (fermented) for one or two weeks. The material is then dried before crushing it into small pieces. Then, these pieces are mixed in water into soupy slurry and then the mixture is pressed in the briquetting machine (briquette press). Fuel briquettes are also made from mixing charcoal dust with binder before introducing the mixture to the briquetting machine (briquette press).

You do not need to carbonize charcoal dust as the lump charcoal the dust comes from has already been carbonized. In every bag of lump charcoal there are charcoal fines occurring from breakages of charcoal when handling. The average quantity of these charcoal fines ranges from 10% to 20% of all the lump charcoal that was produced.

In many countries, all these fines go into waste as they are too small to be used in charcoal stoves. These charcoal fines already contain a lot of charcoal dust and the bigger ones can be pulverised further to make fine dust. These charcoal fines can be obtained for almost free of charge from charcoal vendors.

Carbonizing biomass can be messy and dirty because of the smoke emitted during the charring of the materials and charcoal dust. You must be mentally prepared that this is what you want to do. In that case, you need get yourself protective work garments usually worn over ordinary clothes, dust masks and hand gloves.

You will need to get yourself a 190-litres metal drum like the one shown in the photograph to the right. Once you have the drum make one wide opening at the top of the drum for loading the dry biomass material. Make a metal plate as a cover for that opening of the drum.

At the bottom of the drum, make several holes using a large nail and these holes should be evenly spaced. Let the drum stand on three or four stones such that the drums should be easy to remove when the drum get hot. Load the dry biomass material into the drum through the opening at the top. Under the drum and through the four stones the drum stands on, lit a fire using some papers or very dry leaves.

The fire will soon get into the biomass inside the drum. Air (oxygen) will pass through the holes at the bottom of the drum to support combustion of biomass inside the drum. The biomass will produce a lot of dark smoke. Let it burn for about 10 to 15 minutes and soon the smoke will become less and cleaner. After 10 - 15 minutes, the smoke will become lesser and cleaner. This is the time to close the opening at the top of the drum as well as the holes at the bottom of the drum.