A large number of barite producers utilize flotation to recover and improve the grade of barite used as an additive in drilling mud, the formulation of brake shoe linings, and many other applications.
Commonly used collectors are alkyl sulfates or petroleum sulfonates. AERO 827 promoter has been used for many years in conjunction with sodium silicate to float barite concentrates. The flotation feed is conditioned at 60-65% solids at a pH of 9.5 to 10.2 which is achieved through the addition of 500 to 2000 grams per tonne of sodium silicate. The normal range of AERO 827 promoter required is 500 to 1000 grams per tonne. The feed is normally conditioned for a minimum of five minutes prior to introduction to the flotation cell, where the pulp is diluted to 25-30% solids.
Another collector that has gained wide acceptance is AERO 845 promoter, used either as the sole collector or as a replacement for 10% to 50% of the primary collector, resulting in improved grade and recovery. When used as the sole collector, AERO 845 promoter is added to the conditioner after addition of 1500 to 2500 grams per tonne of sodium silicate. It is recommended that a stage addition of the AERO 845 promoter be used with a total dosage of 150 to 500 grams per tonne. AERO 845 promoter is particularly recommended where selectivity against fluorite and calcite are important considerations.
The combination of AERO 800 series promoters and sodium silicate has been widely accepted for commercial use in separating barite from gangue minerals such as siderite, goethite, hematite, limonite, calcite, fluorite, quartz, and various silicates. Desliming of the feed is not required.
Barite ores often are found containing fluorite. In these cases, AERO 845 promoter is the preferred collector, because of the high degree of selectivity against fluorite in the presence of moderate to large amounts of sodium silicate. If the fluorite concentration is of commercial significance, the fluorite can be recovered from the barite flotation tailings by flotation with a fatty acid collector such as AERO 704 promoter. In most cases, the barite flotation tailings must be de-watered to reduce the concentration of sodium silicate, prior to conditioning with AERO 704 promoter for flotation of the fluorite. Quebracho can be added in the conditioning step to depress calcite, which is often present with fluorite minerals.