Method for separating fine particles by selective hydrophobic coagulation

A method for separating a hydrophobic constituent of a composite material comprising at least one non-hydrophobic constituent from the non-hydrophobic constituent by selective hydrophobic coagulation, comprising the steps of:

• a) pulverizing the composite material in water to form fine particles of the hydrophobic and non-hydrophobic constituents to liberate the hydrophobic constituent from the non-hydrophobic constituent and to form an aqueous slurry, wherein said fine particles have a mean particle size of less than approximately 25 microns;
• b) diluting the slurry to a desired pulp density and adding up to 1% by weight of hydrocarbon oil;
• c) agitating the slurry to selectively coagulate the fine particles of the hydrophobic constituent to form coagula containing said hydrophobic constituent through the action of attractive hydrophobic interaction forces acting thereon as the major driving force, while leaving the fine particles of the non-hydrophobic constituent in a dispersed state;
• and
• d) separating the coagula from the dispersed fine particles of the non-hydrophobic constituent.

A method for separating fine particles of oxidized coal from a mixture of fine particles including at least one component comprising a non-hydrophobic material by selective hydrophobic coagulation, wherein said particles have a mean particle size of less than approximately 25 microns, comprising the steps of:

• a) adding to the mixture of fine particles reagent means for enhancing the hydrophobicity of the coal, said reagent means comprising hydrocarbon oil in an amount which is less than 1% by weight of the clean hydrophobic material produced;
• b) adding water to the mixture of fine particles to form a suspension of the mixture of fine particles in the water having a solids concentration of between approximately 0.5% and approximately 3.0% by volume;
• c) allowing the particles of the coal to coagulate through the action of attractive hydrophobic interaction forces acting thereon as the major driving force for forming coagula containing said hydrophobic material, while leaving the particles of the non-hydrophobic materials in a dispersed state;
• and
• d) separating the coagula from the dispersed particles of the non-hydrophobic material.