GB1086438A - Concentration of phosphate ores - Google Patents

Abstract

Phosphate mineral, e.g. apatite, is separated from a phosphate-containing ore by conditioning an aqueous slurry of the ore with a hydrophylic gum of vegetable origin and separating the phosphate mineral from the slurry by froth flotation. The ore obtained from the mine is crushed and wet ground to liberate the apatite from the other minerals in the ore and to obtain the desired sizing for flotation. After slurrying with water removal of slime is effected, e.g. in a hydrocyclone. The de-slimed slurry is then conditioned at a pH of 7.5 to 10.0 by the addition of the hydrophylic gum which acts as a depressing agent for calcite, magnetite and silicate contained in the ore. A first froth flotation is carried out in the presence of a collecting agent, of which 80% may be added of the slurry enters the flotation circuit and the rest in subsequent flotation cells. The apatite particles adhere to the bubbles formed by the blowing of air or gas in the flotation cells and rise therewith to the surface of the slurry forming a froth which is recovered as a first concentrate which may be directly centrifuged and dried or refined. Alternatively, the first concentrate may be subjected to further froth flotation. The hydrophylic gum of vegetable origin may be a caustic soda-gelatinized starch obtained by agitating one volume of a 10% caustic soda solution with one to two volumes of an aqueous dispersion of about 10% of commercial starch. The suspension is then diluted to about 1% gelatinized starch content. The collecting agent is of an anionic character and may contain a major proportion of unsaturated fatty acids. A portion of the fatty acid may be saponified to maintain the required pH in the slurry. Alternatively, the fatty acid may be used with an olefin of a hydrocarbon oil, such as fuel oil, preferably with an emulsifier. Preferred collecting agents are linoleic and oleic acids and products rich in these compounds, e.g. distillate tall oil and red oil. Examples of the process are given.ALSO:Phosphate mineral, e.g. apatite, is separated from a phosphate-containing ore by conditioning an aqueous slurry of the ore with a hydrophylic gum of vegetable origin and separating the phosphate mineral from the slurry by froth flotation. The ore obtained from the mine is crushed and wet ground to liberate the apatite from the other minerals in the ore and to obtain the desired sizing for flotation. After slurrying with water removal of slime is effected, e.g. in a hydrocyclone. The de-slimed slurry is then conditioned at a pH of 7.5 to 10.0 by the addition of the hydrophylic gum which acts as a depressing agent for calcite, magnetite and silicate contained in the ore. A first froth flotation is carried out in the presence of a collecting agent, of which 80% may be added as the slurry enters the p flotation circuit and the rest in subsequent flotation cells. The apatite particles adhere to the bubbles formed by the blowing of air or gas in the flotation cells and rise therewith to the surface of the slurry forming a froth which is recovered as a first concentrate which may be directly centrifuged and dried or refined. Alternatively, the first concentrate may be subjected to further froth flotation. The hydrophylic gum of vegetable origin may be a caustic soda-gelatinised starch obtained by agitating one volume of a 10% caustic soda solution with one or two volumes of an aqueous dispersion of about 10% of commercial starch. The suspension is then diluted to about 1% gelatinised starch content. The collecting agent is of an anionic character and may contain a major proportion of unsaturated fatty acids. A portion of the fatty acid may be saponified to maintain the required pH in the slurry. Alternatively, the fatty acid may be used with an olefin or a hydrocarbon oil, such as fuel oil, preferably with an emulsifier. Preferred collecting agents are linoleic and oleic acids and products rich in these compounds, e.g. distillate tall oil and red oil. Examples of the process are given.