Treatment of expansible materials to form lightweight aggregate

Apparatus for heat-treating expansible particulate material, in the expanding of same for producing a lightweight granular product, comprising:

• a hearth of annular configuration adapted to rotate in a substantially horizontal plane;
• housing means enclosing the majority of the hearth to provide in succession circumferentially around the hearth preheating and charging and treating and discharging zones;
• supply means for supplying material to be treated to the charging zone of the hearth, so as to be distributed over the hearth;
• heating means for heating the pre-heating zone and the treating zone to an elevated temperature in the region of 1100.degree. to 1300.degree. F. at which at least a partial fusion and expansion of the material takes place;
• discharge means at the discharging zone for causing the resultant expanded product to be removed from the hearth;
• and a
• reciprocating rake adapted to loosen the expanded particles at the discharging zone.

Apparatus for heat-treating expansible particulate material, so as to expand the same and produce a lightweight granular product, comprising:

• a hearth of annular configuration adapted to rotate in a substantially horizontal plane;
• housing means enclosing the majority of said hearth to provide, in succession, circumferentially around said hearth, a charging zone, a treatment zone and a discharge zone;
• supply means for supplying material to be treated to the charging zone of said hearth, so as to be distributed over said hearth;
• heating means for heating the treatment zone of said hearth to an elevated temperature in the region of 1100.degree. to 1300.degree. C. at which at least partial fusion of the material takes place, so as to expand it;
• and
• discharge means, at the discharge zone, for causing the resultant expanded product to be removed from said hearth and including a rake having hollow tines and means for reciprocating the rake to loosen expanded particles and means for supplying fluid through the hollow tines to levitate same relative to the surface of said hearth.

Apparatus for heat-treating expansible particulate material, so as to expand the same and produce a lightweight granular product, comprising:

• an annular hearth adapted to rotate in a substantially horizontal plane;
• housing means enclosing the majority of the hearth;
• the hearth defining in successive angular sectors pre-heating and charging and treating and discharging zones;
• first heating means in the pre-heating zone for heating the empty hearth to a temperature in the region of 1100.degree. C. to to 1300.degree. C.;
• supply means for supplying treatable material to the charging zone in a substantially uniform layer not exceeding three particles in thickness;
• second heating means in the treating zone for heating the hearth and the treatable material thereon to a temperature in the region of 1100.degree. to 1300.degree. C. at which at least partial fusion and expansion of the material takes place;
• and
• discharge means at the discharging zone for causing the resultant expanded product to be removed from the hearth before re-entry into the pre-heating zone.