GB1406093A - Process for removing impurities from carbonaceous material and manufacturing of hard ashless charcoal briquettes - Google Patents

Abstract

1406093 Purified charcoal briquettes J F SYMONDS 4 Sept 1972 40897/72 Heading C1A [Also in Divisions C5 and C7] Substantially pure carbon is obtained by placing a container containing a finely divided carbonaceous material in the vicinity of an electrode of an electrolytic cell containing dilute sulphuric acid as electrolyte, the material is electrically connected to the electrode and a potential is applied to the electrode, whereby inorganic impurities in the starting material are converted to soluble or volatile compounds or ions, the container is removed from the electrolyte to a wash vat where the material is washed to remove soluble compounds or ions to give said substantially pure carbon. The electric potential on the electrode may be reversed for periods of 1 to 12 minutes during the treatment. Hard ashless charcoal briquettes may be obtained using the above process, by drying the carbon product, and compressing it at a temperature of at least 550‹ C. and a pressure of at least 200 tons/in.<SP>2</SP> and then curing the briquettes in the presence of carbon dioxide at a pressure of at least 50 tons/in.<SP>2</SP> for at least 20 hours. The carbon may be treated in the electrolytic cell at a potential of 3À5 to 24 volts with a current density of 40 to 80 amps/square foot for at least 10 mins., the sulphuric acid concentration of the electrolyte being 5 to 40% by weight. The silicate content of the so purified carbon may be reduced by treatment with a 10 to 20% solution of HF. If desired the carbon material purified by the electrolytic process may be obtained from a suitable vegetable source, e.g. wood, vines, shrubs, forest or agricultural waste, by carbonizing this material, for example by treatment with concentrated sulphuric acid, e.g. of a concentration of 50% to 100%, the source material being ground, e.g. to a size of # to “ inch to produce the desired finely divided carbonaceous material as a starting material for the electrolytic treatment. Suitable charcoals may be obtained by other carbonizing processes provided they are ground to the indicated degree of fineness either before or after carbonizing treatment. The briquettes said to be useful as fuel in blast furnaces may have a specific gravity of 3À16 to 3À18, a hardness of 9 on Mhos scale, and a heat value of 40,000 to 45,000 Btu per pound when moulded at 500 tons/sq. inch and 1500‹ C. Different figures are given for briquettes moulded under different conditions, but the process is said to improve the fuel value of charcoal briquettes.