GB393128A - Manufacture of calcium cyanamide - Google Patents

Abstract

Calcium cyanamide is obtained by causing nitrogen to act on finely granulated calcium carbide which is constantly kept in motion, the absorption of nitrogen being started at a relatively low temperature and the temperature being then permitted to increase at a sufficiently slow rate to prevent agglomerating until the final required temperature is attained. The temperature may be controlled by controlling the supply of external heat or the supply of nitrogen. The initial temperature may be 600-950 DEG C., which may be increased to final temperatures of 950-1050 DEG C. in periods of from 6-60 hours. The increase of temperature may be in steps say of 50 DEG C., each increase being permitted only after the absorption of nitrogen following the previous increase has ceased. Catalysts such as calcium chloride, calcium fluoride or calcium cyanamide or inert diluents such as calcium cyanamide or lime may be added to the calcium carbide and the presence or absence of such additions or the granular size of the carbide affects the allowable initial temperature or rate of increase thereof. The granular calcium carbide may contain some carbide in the form of dust. The nitrogen may be diluted with inert gases. The process may be carried out by introducing granulated calcium carbide and nitrogen continuously into an externally electrical-resistance heated rotating drum, the carbide moving continuously through the drum, which has a temperature of 780 DEG C. at the inlet and 1000 DEG C. at the outlet. Examples are given. Specifications 107,754 and 123,796, [both in Class 1 (ii), Inorganic compounds, other than &c.], are referred to.