Fluorite mineral processing technical information

Mineral fluorite (processing of fluorspar ores)

The process of sorting out fluorite concentrates from fluorite ore. Fluorite, also known as fluorspar, has a chemical composition of CaF2 and is usually symbiotic with quartz , calcite , barite , and clay . Fluorite in metallurgical industry mainly used as a steel slag flux smelting, the chemical industry for producing hydrofluoric acid and a fluoride fluorite. Fluorite is also an important raw material for industries such as plastics, ceramics and cement. The quality standard of fluorite concentrate is generally divided into metallurgical grade according to its end use: CaF2 ≥ 80% ~ 85%, SiO2 ≤ 5%, CaCO3 ≤ 4% ~ 5%, PbS ≤ 0.7%; ceramic grade: CaF2 ≥ 95% , SiO2 ≤ 3%, CaCO3 ≤ 1.0%, Fe2O3 ≤ 0.12%; acid grade: CaF2 ≥ 97%, SiO2 ≤ 1.0%, CaCO3 ≤ 1.0%.

In addition to the main minerals of the deposit, fluorite is a metal deposit, especially associated minerals of lead and zinc deposits. The fluorite deposit is divided into quartz-fluorite deposit, carbonate-fluorite deposit and polymetallic fluorite deposit. The world's largest fluorite mine is located in Transvaal, South Africa.

The beneficiation methods used in the separation of fluorite are mainly hand-selected, re-elected and floated. Among them, the flotation method is the most widely used. Hand-selected for the treatment of coarse, massive fluorite. It can be sorted according to +200mm, 200～30mm, 30～15mm, 15～0mm four grades, and its use is determined according to the concentrate grade and impurity content. Re-election is suitable for the production of metallurgical lump or as a pre-selection for flotation. Usually, the ore or hand-selected tailings are crushed to 25~30mm or less, and are selected by screening and classification. The fine-grained grade is sorted by the jigging beneficiation method or the shaker beneficiation method; the coarse-grained grade is sorted by the heavy medium beneficiation method, and the ferrosilicon is commonly used as the weighting property. When the ore is included in heavy minerals such as barite and galena, the fluorite is recovered as the first weight, otherwise it will be enriched in the heavy product. Flotation is mainly used in the production of high grade concentrates for the chemical and ceramic industries.

Typical processes are the quartz – fluorite ore flotation process and the carbonate – fluorite ore flotation process. The fluorite in the polymetallic ore is recovered as a by-product. The flotation of fluorite is usually carried out by using a fatty acid such as oleic acid or oxidized paraffin soap or other soap as a collector , and the slurry is subjected to a pH of 8 to 10 and a slurry temperature of 25 ° C or higher. Commonly used pH adjusters are sodium carbonate and caustic soda. The gangue inhibitors include water glass, tannin, tannin, sodium lignosulfonate and white bark juice. To ensure the quality of the concentrate, it is selected at least three times.

Quartz – Fluorite Ore Flotation Process This process is used for the separation of quartz-based fluorite ore associated with impurity minerals. The fluorite crystal size is extremely uneven, ranging from a few microns to tens of millimeters, and is closely symbiotic with quartz. Other impurity minerals include calcite, pyrite, and kaolinite. The ore is of an easy-to-select type, and is generally selected by using a fatty acid collector such as oleic acid in an alkaline medium to obtain a qualified concentrate. Commonly used water glass is used as a quartz inhibitor, but the dosage should be strictly controlled. When the dosage is small, the fluorite is activated. If the amount is too much, the fluorite is inhibited. It is also often added by adding a polyvalent metal cation such as Al3+ or Fe2+ and a calcite such as alum or aluminum sulfate. The structure of the process is characterized by multi-stage grinding. The choice of regrind location and medium ore treatment options will vary depending on the ore size characteristics of the ore and the quality of the concentrate. The process structure has coarse concentrate re-grinding and medium-mine sequence return; coarse concentrate re-grinding and medium-mineral treatment; medium-mineral re-grinding return and medium-mine re-grinding separately. The typical process is shown in Figure 1, which is the beneficiation process of China Dongfeng Fluorite Company. There are two types of ore processed by the company: fluorite lump ore, CaF2 grade <40%, fluorite and quartz inlays are fine, difficult to grind; clastic mine, particle size – 20mm, grade 55%～65%, quartz Less content, easy to grind and easy to choose. The process is to crush the raw ore, carry out rough grinding and flotation, re-grind the coarse concentrate and make it through six selections. The oleic acid is used as a collector and the sodium carbonate is used as a regulator. Water glass is used as an inhibitor. The main selection indicators are concentrate CaF2 ≥ 98%, SiO2 ≤ 0.8%, and CaF2 recovery ≥ 74%.

Carbonate – Fluorite ore flotation process The main associated minerals of this ore are calcite, barite, quartz, etc. This type of ore is a refractory ore. Because fluorite, calcite, and barite are very similar in floatability, it is often necessary to have a selective inhibitor to effectively separate them. Commonly used inhibitors are water glass, ammonium hydrogen chloride, tannin, tannin, sodium lignosulfonate and white bark juice. The inhibitors used are mostly two or more combinations. Typical processes, such as the Alcoa concentrator process in the United States, are shown in Figure 2. The plant first uses heavy medium selection and flotation to remove metal minerals such as galena and sphalerite associated with fluorite ore, and then produces acid grade fluorite concentrate by flotation. Fluorite flotation is carried out in an alkaline medium. Oleic acid is used as a collector, sodium carbonate is used as a pH adjuster, and tannic acid is used as a calcite inhibitor. The ore contains CaF2 50.0%, Pb 1.3%, Zn 0.7%, SiO2 15.5%, CaCO3 24.7%; fluorite concentrate grade: CaF2 97.6%, SiO2 0.7%, CaCO3 1.4%.