GB865325A - Improvements relating to the preparation of calcium carbide in a shaft furnace - Google Patents

Abstract

<PICT:0865325/III/1> In a process for the production of calcium carbide in a shaft furnace from a solid carbon fuel and lime or limestone by means of an oxygen-rich blast (as defined) a part or all of the blast is introduced so as to pass into and through the pool of molten calcium carbide which collects in the bottom of the furnace p hearth. The oxygen rich blast may be any blast of say oxygen enriched air, oxygen/steam mixture or oxygen alone but contains at least 50% by volume free oxygen. A mixture of lime or limestone and coke in proportion of say 1:2 by wt. and of particle size ranging from 5-100 preferably from 10 to 30 mm. and especially 20-25 mm. is fed through bunker 3 of test furnace 1, oxygen being admitted through tuyeres 2. Co-containing gases evolved during combustion are removed from the furnace at 4 and the pool of molten carbide which collects in the bottom of the hearth is drained either continuously or periodically through discharge port 5 and channel 6, the rate of drainage being controlled so that the level of the molten pool in the furnace remains above the inlet openings of the tuyeres so that oxygen introduced during the reaction passes into and through the molten carbide. Modifications of the furnace whereby a second discharge port is positioned in the furnace wall above the inlets of the tuyeres for removal of the molten carbide the lower port 5 being thereafter used for the periodic removal of heavy molten slag, e.g. ferrosilicon formed from the impurities in the melt, and the use of tuyeres positioned at different levels in the furnace wall such that one or more inlets are below and one or more inlets are above the surface of the pool of molten carbide at the bottom of the hearth, are referred to.