Charcoal made out of the modified pit method can be used in making charcoal briquettes. Charcoal briquettes are charcoal dust compactly massed by a binder of either cassava flour, corn or sweet potato starch.
As fuel, charcoal briquettes have higher heating value than wood or plain charcoal. They are almost smokeless when burning and give off intense and steady heat. They can be used in the smelting of iron ore since it is compact and dense.
Aside from their used as fuel, charcoal briquettes can be converted to other industrial products. In the chemical industry, they are used in the manufacture of carbon disulfide, carbon electrodes, carbon tetrachloride,
carbon carbide, sodium cyanide and activated charcoal for purifying air or water.
Materials and Equipment
To make the charcoal briquettes, you need well-charred charcoal made through the modified pit method and cassava corn or camote starch as binder.
Hammer mill or wooden mallets, pail, mild and a tapahan type dryer are also needed.
Charcoal briquettes can be produced manually or mechanically. For a small-scale briquettes maker, the manual method will suffice. The method is simple and can easily applied in places where coconuts abound.
First, prepare or have ready smokeless charcoal. This type of charcoal is shiny and gives a metallic sound when tapped. Powder the charcoal into dust particles by hammering with a mallet or wooden hammer or by passing through a hammer mill.
Cook cassava corn or camote starch under moderate heat. The starch should have a syrupy consisting which is neither too thick nor too thin. This will be used as binder.
Mix thoroughly the charcoal dust and the binder in a pail or any available container. When the mixture has reached an even consistency, knead in the same ways making dough for bread.
Molding the resulting mixture into desired shape and size using the hands or an improved wooden molder such as a sungkahan.
The dry briquettes under the sun. Better still, oven cook them in an improvement tapahan type dryer using pieces of wood, coconut shells and dusks and other waste materials for fuel.
Making of charcoal briquettes can be practically costly if undertaken in areas where coconut shells or other suitable materials are discard as waste.
Materials for Briquetting
Only materials which would produce soft and poor quality charcoal should be used for charcoal briquetting. It is not advisable to convert hard charcoal into charcoal briquette. Big charcoal manufacturing establishments, could put up charcoal briquettting units to convert charcoal fine and small broken charcoal particles into briquettes.
Studies show that in charcoal manufacturing establishments, fine waste constitutes 10 to 15 percent of usable charcoal. To ensure a smokeless charcoal briquette, the charcoal fine must be well-charged, that is, it must contain at least 75 percent fixed carbon and not more than 24 percent volatile matter.
For big scale (one ton per hour and up) briquetting, charcoal fines and lump charcoal may be combined as raw materials.
Materials recommended for charcoal briquetting are:
- Charcoal fines accumulated during charcoal manufacturing, handling, and transporting;
- charcoal from low-density wood and bulky materials like coconut husks, corn cobs, etc.;
- charcoal from wood wastes during logging, lumbering and veneering such a log ends, stumps, branches, twigs, barks and trimmings;
- charcoal from the fine agro-forestry waste materials such as sawdust, ricehull, and coconut coir dust; and
- charcoal from tree plantations.
These materials abound in the country. Their use in charcoal briquetting creates jobs and generates more income and recycles waste in the countryside into a useful commodity.
Binders for Charcoal Briquetting
1. Smokeless binders :
- Meal binders such as cassava starch, corn starch, and other starches are smokeless but not moisture resistant. they are normally used in the range of 4 to 6 percent on the oven-dry basis. In some cases, small amounts of moisture resistant binders are used.
2. Smoky binders :
- Smoky but moisture resistant binders are tar, pitch, asphalt, sugar cane molasses, and others. Recommended percentage for wood- tar pitch and coal-tar pitch is less than 30 percent. Briquettes with these blinders are smoky when ignited. But this characteristic is not a drawback for briquettes used in smelting and heating. For home use it could be very annoying.
Manufacture of Charcoal Briquettes
a. Mechanical Process
Charcoal is manufactured either mechanically or manually. A lot- size briquetting machine installed at the Forest Products Research and Development Institute (FPRDI) produces better quality briquettes faster. The steps in manufacturing charcoal briquettes are:
a1. Preparation of Charcoal Fines:
Use charcoal material with low moisture content and high fixed carbon content. If lump charcoal is used, pass these through a primary crusher, then through a disintegrator. This process is skipped if charcoal is fine like those obtained from sawdust, rice hull, and other agro-forestry fine materials such as those accumulated during charcoal manufacturing.
a2. Mixing Charcoal Fines with Binder
Charcoal fines is mixed with binder which could be any of gelatinized starch of pastry consistency, liquid tar, molasses, or heated asphalt. Mixing usually use a kneader type, double- shaft mixer. This process is one of the most critical operations in the manufacture of charcoal briquettes. Efficient mixing is essential to obtain a strong product.
a3. Briquetting of the Mixture
After thorough mixing of charcoal fines and the binders, mixture is fed into the molds where pressure is applied to make the particles compact. The size and shape of the briquettes go with the molds. The most common is the ovoid-type or pillow-shaped briquettes.
a4. Drying of the Briquettes
Briquettes are dried first before packaging, to make them strong. They are dried in a batch-type or continuous dryer.
b. Manual Process
For small-scale briquette manufacturing, the manual method is recommended. Although, this method is time-consuming and produces irregularly shaped briquettes, it is good alternative for small- scale operators who cannot afford an expensive briquetting unit. It is also ideal for housewives and amateur charcoal briquettes makers who are willing to experiment.
The same operations and principle used in the mechanical method are applied in the manual method. The only difference is the use of the hand in the manual technique.
First, the charcoal fines and binder are separately prepared. Charcoal fines are pulverized into soft or low quality charcoal with a hammer or mallet. The binder is made by simply sun-drying sliced cassava or sweet potato for about one week the pulverizing them until they turn into starch. Corn starch may also be used. It is cooked into a syrup consistency, neither too thick nor too thin.
In a pail or any suitable container, mix thoroughly the charcoal fine and the binder by kneading. The mixture is molded into desired shapes and sizes by hand. An improvised wooden molder may also be used.
Dry the molded briquettes under the sun for about three days. Or better still, dry them in an improvised “tapahan” type dryer fueled by wood, coconut shell or husk or other waste material. When the briquette moisture goes down to 10 percent, the briquettes are removed from the dryer.
source: region10.dost.gov.ph, photo from commons.wikimedia.org