Integrated charring and ore reduction

摘要

A continuous process employing a pair of rotary kilns for reducing oxidic ore bearing material in the presence of hot combustible gases and a solid carbonaceous reductant of low volatile content, characterized in continuously feeding a high volatile solid carbonaceous reductant through the first kiln 11 whilst heating to produce a low volatile char with evolution of hot combustible gases; passing said hot gases as evolved into the second kiln 10, whilst also passing therethrough a mixture of ore and low volatile char, part, at least, of which comprises the char formed in the first kiln 11; and reducing the ore bearing material therein by burning said combustible gases with oxygen containing gas, introduced into the kiln at rate such as to provide the requisite temperature for reducing said ore bearing material. In the embodiment described the charring of the carbonaceous material in the first kiln is effected by burning a portion thereof by controlled introduction of an oxygen containing gas. In each kiln the air is introduced at points 42, and 30 spaced along the length thereof. The volatile char is discharged from the first kiln in a hot state and may be fed immediately into the second kiln (via the path 56), or it may be fed, with the discharge from the second kiln successively through a quenching tank 58, where it is quenched to atmospheric temperature, and a separator 59 for removing the ash and separating the iron values from the recycle coke or char, to a rotatable hopper 61; or it may be fed into a mixer 65. The material fed to the hopper 61 may be fed to the second kiln via the hopper 62 and path 63, or may be passed into the mixer 65 and thence to sieve 67, the fines being returned to the second kiln 10 and the oversize material being passed to a grinder 70 and thence returned to the sieve.