October 28, 2013 at 11:25 am #2586
The following question was asked by Mr. Najeeb Kunjimoidu:
i have planned to produce charcoal briquettes, which is is all ways an ecofriendly programme. but please give me guidance regarding its ingredients, especially the binder. from various sources i came to know that cassava starch is the best, but i have a doubt regarding its moisture absorbing property. do cassava starch really have such a property? if yes, then is there anything else such as a filler, that can be added to counteract this without compromising the quality of the briquette? what is the percentage of cassava starch that should be added? if there is any liquid starch available in food grade standard that can be used for producing briquettes. are they really useful for domestic purposes? does charcoal briquettes produce light wieghted ashes that may settle on the barbeques?
please do reply me soon….
NajeebpkNovember 10, 2013 at 8:05 pm #2636
Dan SweeneyKey Master
Hello Mr. Kunjimoidu,
Thank you for your interesting questions regarding materials for binding char into fuel briquettes. You are correct, cassava and similar powdered starch binders are typically used in fuel briquette production. You are also correct that cassava and other starch-based binders are hygroscopic, or tend to absorb moisture. This presents a significant challenge if humidity is high or there is a possibility that the briquettes will be exposed to rain or other precipitation. There is some research being conducted to investigate binders additives which enhance non-hygroscopic properties of fuel briquettes. One approach that looks particularly promising, especially in the context of developing countries, is the addition of pyrolysis tar, or pyroligneous acid, to starch binders. The oily, combustible tars are highly non-hygroscopic and may help to make the fuel briquette water resistant. In addition, pyrolysis tars can be captured relatively easily from charcoal kilns (see the related forum post by Cookswell Jikos)! I’m sorry that I don’t have any more guidance regarding this, but I would encourage you to experiment with binder additives and share your results here at the Harvest Fuel Initiative.
In general, about 4-8% (by weight) starch powder is necessary to create briquettes with good mechanical strength and durability. This amount depends on the feedstock used to make the charcoal, the degree of carbonization and char particle size after grinding and sieving. From my experience, much of the starch powder used for briquette binder is food grade and expensive. However, some enterprises that I have spoken with are making binder using inexpensive spoiled starch roots (e.g. cassava) which are not suitable for food use. Another approach may be the use of clay instead of food grade starches. Again, please share your experiences regarding this if and when you have some.
The ashes produced during briquette combustion are light weight and generally settle in the cook stove or barbecue rather than entrain in combustion gases as fly ash. However, there are some problems associated with emissions of fine particles from wood and charcoal cook stoves.
Thanks again for your questions and comments, and we look forward to learning more about your experiences with charcoal briquettes!
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