Improvements in or relating to the manufacture of synthetic aggregates

摘要

Aggregates are prepared from clay or material containing clay such as pulverized fuel ash, finely divided slag, shale or mixtures thereof by mixing the material with water and additional clay where necessary to a consistency such that when the mixture is divided into granules the granules will not readily adhere to each other or break up, dividing the mix into granules by extruding the mix and cutting the extruded material into lengths, feeding the granules to a kiln in which the atmosphere is dry and at a temperature of 150-200 DEG C., progressing the granules through the kiln in the presence of a gaseous oxidizing agent, sintering the granules and discharging them from the kiln. Fluxes and/or a foaming agent may be added to the mix before extrusion. Fig. 1 shows clay emulsifier 4, clay emulsion hopper 6 and ash hopper 10, both hoppers leading via metering valves to mixer conveyer 16 which discharges into granulating mill 30 which discharges the formed granules into inlet hood 50 of rotary kiln 54 fitted with radial vanes 82, gas burner 86 and annular discharge weir 88. The granulating mill is shown in Fig. 12 where roller 34 is eccentrically mounted within perforated drum 30, rotation thereof causing the mix to be extruded through the perforations and cut into lengths by means of wire cutters 121 when they fall on to conveyer belt 136 where they are coated with sand which is fed to the belt from hopper 130.