Inorganic Binders
There a many kinds of binders which can be used for charcoal briquetting. To produce briquettes with less smoke on combustion, inorganic binders such as sulphite-liquor residues, molasses or starch may be a good choice. In generally, inorganic binders won’t lead to smoke problem since they do not volatilize until decomposed, but some inorganic binders such as petroleum residues and pitch tars volatilize, if the gases formed are not completely burned, they will cause possibly odor and smoke.
To some extent, a regular briquette shape allows a better-regulated air supply, which means more complete combustion. In another word, even when using these binders, it is quite possible to regulate the conditions, in such a way that the charcoal briquettes will produce less smoke than the lump coal from the screenings of which the briquettes are made. This is also seen as one big advantage to turn slack coal into briquettes.