Non-fused aluminium oxide-based abrasive mineral, a process for its production and abrasive products comprising the said abrasive mineral

Claim 1

Method of making, synthetic, aluminum oxide-based abrasive mineral characterized by having a dense, granular, substantially homogeneous microcrystalline structure of randomly oriented crystallites comprising modifying component in a dominant continuous alumina phase comprising alpha-alumina, said method characterized by the steps of: (a) gelling a substantially calcium ion- and alkali metal ion-free homogeneous mixture of an alumina source compound and at least one precursor of at least one modifying component selected from (i) zirconia, hafnia, or a combination of zirconia and hafnia, and (ii) a spinel derived from alumina and at least one oxide of a metal selected from cobalt, nickel, zinc, or magnesium, said precursor being present in an amount to provide in said mineral a dominant continuous alumina phase comprising alpha-alumina and a modifying component content, on a volume percent of fired solids of the mineral, of either (a) at least 10% of said (i), (b), at least 1% of said (ii), or (c) at least 1% of said (ii) and 1-45% of said (i), (b) drying the gelled mixture to form chunky pieces of solid material, and (c) firing said solid material in a non-reducing atmosphere to a temperature of at least 1250°C., but not above the melting point of said mineral, to remove fugitive materials and to nondestructively convert said solid material to a dense aluminum oxide-based mineral.