Improvements in or relating to methods of producing light-weight building materials of slate, slate-clay, or the like

摘要

Expanded slate or slate clay is produced by mixing slate or slate clay of particle size of 1-20 mm. with sand or other refractory material of a particle size of up to 2 mm., passing the mixture through a heated rotary kiln and separating the sand from the resultant product. If necessary, the slate or slate clay may be ground initially to a finer state of subdivision than that specified above, the fine material formed in granules, and these granules utilized in the above process. The sand or other refractory material may be added by coating the still moist granules with it prior to calcining. Furthermore, the fine and very fine fractions of slate or slate clay produced during comminution may be granulated, and the granules mixed with the large particles of slate or slate clay, prior to mixing with sand or other refractory material and calcining.