Production of calcium carbide

A process for making calcium carbide by reacting an excess of coke with quicklime in the presence of oxygen in an oxygen-thermal furnace, which comprises:

• using precrushed coal as a starting material for coke and precrushed lime hydrate (Ca(OH).sub.2) or precrushed limestone (CaCO.sub.3) as a starting material for quicklime;
• mixing the precrushed materials, introducing the resulting mixture into a drying zone and freeing it therein at 80.degree. to 120.degree. C. from adhering water;
• introducing the warm mixture coming from the drying zone, and air, into a calcining apparatus, the coal constituent being coked and the lime constituent being simultaneously dehydrated or decarbonized therein at temperatures of 900.degree. to 1400.degree. C.;
• directly delivering the thermally-pretreated mixture of starting materials with an inherent temperature of 900.degree. to 1000.degree. C. to the oxygen-thermal furnace and reacting it with oxygen to produce calcium carbide therein, using the waste heat originating from the calcining apparatus for the generation of superheated high pressure steam from boiler feed water;
• using the superheated high pressure steam for operating a turbine, the latter being used for the liquefaction of air and separation into its components at low temperature so as to obtain the oxygen necessary for operation of the oxygen-thermal furnace, and also for the generation of electrical power, hot low pressure steam issuing through the turbine's opposite side being introduced at least partially into the drying zone for drying the mixture of starting materials therein;
• and taking condensate obtained in the drying zone therefrom, preheating it by means of off-gases originating from the oxygen-thermal furnace, and using it as boiler feed water for the generation of superheated high pressure steam by means of waste heat originating from the calcining apparatus.