Abstract: A granular material which includes an inorganic substrate has a ceramic coating which substantially reduces dust generation during processing of the granular material. The ceramic coating comprises the reaction product of an alkali metal silicate and an aluminosilicate, the ceramic coating further including a magnesium complex and an alkali metal chloride. The magnesium complex and alkali metal chloride are dispersed within the coating. It has been found that the use of magnesium chloride alone eliminates the use of oil in preventing dusting of the resultant granule material. Methods of producing such ceramic-coated granular materials are also disclosed, as well as methods of reducing dust generation using magnesium chloride.

Abstract: Roofing granules having surfaces treated with a polysiloxane that has a long-chain hydrocarbon group bonded to a silicon atom on the polysiloxane backbone wherein the long-chain hydrocarbon group preferably is a straight or branched aliphatic group having 5 to 30 carbon atoms and the roofing granules treated with such polysiloxanes demonstrate good dust control and water repellency, and also resist staining from oils in asphalt-based substrates.