GB355664A - Improvements in or relating to the roasting of ores containing iron and copper sulphides - Google Patents

Abstract

Copper pyrites containing valuable constituents such as silver and molybdenite is roasted at a temperature not exceeding 500 DEG C., regulated quantities of air being supplied during treatment and uniform composition of roasting gases being maintained, whereupon both iron and copper may be magnetically separated from the residue. The temperature range may lie between 430 and 470 DEG C., and in the case of argentiferous fine ore 440 DEG C. is preferable. The furnace is of the shelf type as described in Specification 255,432, [Class 51 (ii), Furnaces and kilns for applying &c.], and comprises a number of compartments 1 with hollow bottoms 2. A vertical revolving shaft 6 is rotated by a gear wheel 8, the slot and key connecting them together enabling the shaft to be axially <PICT:0355664/III/1> displacable. The material in the compartments is distributed by means of spiral-shaped rabbles 12 and falls from the upper compartment to the lower one through peripheral openings 15. In this compartment the windings of the rabble are in the opposite direction so that the material is conveyed towards the centre from where it falls into the lowermost compartment through central openings 17. This compartment has a corresponding rabble and discharge openings to those in the uppermost compartment. The furnace is heated electrically and may be heat insulated. Air is supplied to each compartment from a main 24 and branches 25 having valves 26. The gases issue through pipes 27 and regulating valves 28 to a common flue 29. The draught in the latter is regulated by rotation of the pipe 33 which leads to a flue 36 containing a fan. Air is blown into the hollows of the bottoms from main 37.