HARD FOAMED PEARLITE AND ITS MANUFACTURING METHOD

PROBLEM TO BE SOLVED: To provide a method for efficiently and stably manufacturing hard foamed pearlite being fine, spherical and highly strong where non-granulated rock grains are used as a raw material and to provide the hard pearlite. SOLUTION: Rhyolitic non-granulated rock grains having an average grain diameter of 5 mm or less and a moisture content of 6 wt.% or less, favorably 3 wt.% or less, are used as the raw material. Different baking processes corresponding to the average grain diameter and the moisture content of the rock grains are performed. Specifically, the hard foamed pearlite having an average grain diameter of 5 mm or less, a sphericity of 0.7 or more and a compressive strength of 25 N/mm2or more is manufactured by one-stage combustion for raw material rock grains having an average grain diameter of 0.6-5 mm and by two-stage combustion for raw material rock grains having an average grain diameter of 50 μm-0.6 mm. COPYRIGHT: (C)2008,JPO&INPIT