Abstract: Spherical and rod-shaped proppants and anti-flowback agents made from sillimanite minerals possess high strength and high conductivity. The sillimanite minerals may be selected from the group consisting of kyanite, sillimanite, and andalusite and may be used alone or in combination with other materials, such as bauxite, kaolin, meta-kaolin, pure or technical grade alumina (about 98%-99.9% alumina by weight), alumina-containing slag, zirconia, silica, iron, alkali elements (such as calcium, magnesium, and sodium), and virtually any other mineral containing alumina. The starting material may optionally be milled to achieve better compacity and crush resistance in the final proppant or anti-flowback agent. A fracturing fluid may comprise the rods or spheres alone, or in combination with each other or other proppants or anti-flowback agents of different shapes.

Abstract: Spherical and rod-shaped proppants and anti-flowback agents made from sillimanite minerals possess high strength and high conductivity. The sillimanite minerals may be selected from the group consisting of kyanite, sillimanite, and andalusite and may be used alone or in combination with other materials, such as bauxite, kaolin, meta-kaolin, pure or technical grade alumina (about 98%-99.9% alumina by weight), alumina-containing slag, zirconia, silica, iron, alkali elements (such as calcium, magnesium, and sodium), and virtually any other mineral containing alumina. The starting material may optionally be milled to achieve better compacity and crush resistance in the final proppant or anti-flowback agent. A fracturing fluid may comprise the rods or spheres alone, or in combination with each other or other proppants or anti-flowback agents of different shapes.

Abstract: Spherical and rod-shaped proppants and anti-flowback agents made from sillimanite minerals possess high strength and high conductivity. The sillimanite minerals may be selected from the group consisting of kyanite, sillimanite, and andalusite and may be used alone or in combination with other materials, such as bauxite, kaolin, meta-kaolin, pure or technical grade alumina (about 98%-99.9% alumina by weight), alumina-containing slag, zirconia, silica, iron, alkali elements (such as calcium, magnesium, and sodium), and virtually any other mineral containing alumina. The starting material may optionally be milled to achieve better compacity and crush resistance in the final proppant or anti-flowback agent. A fracturing fluid may comprise the rods or spheres alone, or in combination with each other or other proppants or anti-flowback agents of different shapes.

Abstract: The invention provides particulate natural magnesium hydroxide (e.g. brucite) having a d90 less than or equal to 6.2 ?m, as measured by CILAS, and a particulate filler material for use in a polymeric composition, particularly but not exclusively a flame-retardant polymeric composition, the filler material comprising the particulate natural magnesium hydroxide and optionally one or more other particulate inorganic material (e.g. alumina trihydrate).

Abstract: A process for improving the brightness of an alkaline earth metal carbonate utilizing formamidine sulfinic acid or sodium dithionite as a reductive bleaching agent is disclosed. Where the alkaline earth metal carbonate is calcium carbonate, addition of the reductive bleaching agent to an aqueous slurry of the calcium carbonate takes place prior to, during, or after formation of the carbonate, which is chosen from at least one of a precipitated calcium carbonate and a ground calcium carbonate.