Fluorite Ore Beneficiation Process Machinery And Production Line

Fluorite (CaF2) is an important fluorine mineral, which is mostly used for the production of hydrofluoric acid and as a flux in steel making. Other uses are the manufacture of glass, fiberglass, pottery and enamel, etc.

Most fluorite ores have to be upgraded before entering the fluorite market. The most commonly used beneficiation process is froth flotation, producing fluorite concentrates of up to 99% purity.

Crushing Fluorspar Ore

For the average small mill treating up to 100 tons of ore a day, primary crushing is usually adequate and very economical. Larger tonnage will require primary and secondary crushing for maximum efficiency in size reduction and subsequent ball milling.

Grinding Circuit

Fluorspar ores usually require grinding to 48 or 65 mesh to liberate the calcium fluoride from the gangue impurities.

Ball mill grinding with a Steel Head Ball Mill in closed circuit with classifier is the general practice. In larger plants, particularly when fine grinding is necessary, thickening of the classifier overflow is necessary to maintain proper density and feed regulation to flotation. This thickening step on fluorspar ores containing sulphides is usually between the sulphide and fluorspar flotation circuits. Reagents used for selective flotation of lead and zinc then can be rejected in the thickener overflow water.

Fluorspar Flotation

Flotation of fluorspar must be extremely selective when producing acid grade concentrate. This selectivity is essential as the ratio of concentration is low, often up to 80% or more of the entire tonnage, and must be floated in the rough circuit. Cleaning by two or more stages of flotation must bring the rougher product up to acid grade and at the same time retain a high weight recovery with a minimum circulating load.

The “Sub-A” Flotation machine, the accepted standard in all fluorspar flotation plants, has been adapted specially for fluorspar treatment with provision for multi-stage cleaning and recirculation of middling products without the need of auxiliary pumps. Cleaner tailings may be conveniently removed at any point in the circuit. The flowsheet on the reverse side of this page shows one of the many possible cell arrangements used in treating fluorspar ore.

Thickening and Filtering

Thickening of fluorspar concentrates offers no special problem. Thickener capacity, however, should be adequate to handle the tonnage and have ample storage capacity during possible interruption in the filtering and drying sections. Fluorspar flotation froth has a tendency to build up on the thickener surface, but this can be taken care of by retaining rings near the overflow lip and by sprays so only clear water overflows the thickener. Thickened concentrates at 50 to 60% solids is removed by a Adjustable Stroke Diaphragm Pump, feeding by gravity to the filter.

Fluorspar is extremely rapid filtering even when ground fine, provided a non-blinding filter media is used. The rotary fluorspar type filter with stainless steel filter media, heavy duty oscillating mechanism, oversize valve and ports, and high displacement vacuum pump is standard for fluorspar flotation concentrates and will discharge a filter cake with as low as 6% moisture. In the event the filtrate is slightly turbid or contains solids, it should be diverted back to the thickener. For this reason a adjustable stroke diaphragm pump is often used in place of the conventional centrifugal filtrate pump.

Drying and Storage

Fluorspar flotation concentrates of acid grade must be dried to less than 0.5% moisture. Dust losses are kept to a minimum by providing a closed system with a cyclone to insure only vapor laden air discharging to the atmosphere. Enclosed screw conveyors, elevators and often air-born systems are used to transport the finely divided dried acid spar to the storage bins. Provisions should be made for handling efficiently the hot concentrate discharging from the dryer. The Standard Dryer is ideal for this purpose.

Typical equipment list for a 100 ton per 24 hour acid grade fluorspar flotation plant producing 50 tons of concentrates per day when grinding a medium soft ore to 48 mesh.