Experimental Study on Beneficiation of a Quartz Fluorite Ore in Hunan Province

Fluorite also called fluorspar, is the nature of fluorine-highest non-metallic minerals, mainly used in chemical, metallurgy, glass, ceramics and other industries. Fluorite in nature often coexists with various minerals such as calcite , quartz , barite , kaolinite, etc. The symbiotic type with other minerals directly affects its utilization value in smelting, cement and other industries.

There are three main types of fluorite ore, namely quartz-fluorite type, barite-fluorite type, calcite-fluorite type, and the sorting method plays a decisive role in its end use. For the quartz-fluorite type ore with quartz as the main gangue, due to its relatively simple mineral composition, it is often used for rough grinding, coarse concentrate regrind, and multiple selected processes. Under normal circumstances, the chemical system uses sulfuric acid or sodium carbonate as the pH adjuster, water glass as the main inhibitor of gangue such as quartz, and the collector uses oleic acid, so that the gangue such as fluorite and quartz can be better separated. , to obtain qualified fluorite concentrate products. In the flotation process, care should be taken to avoid the activation of quartz and other silicate minerals by metal ions such as Ca2+, Fe3+, Mg2+, etc., and to control the mass fraction of SiO2 in the concentrate.

1. Raw ore properties

The test ore sample was taken from a quartz-type fluorite ore in Zhuzhou City, Hunan Province. The ore grade was 30%, the main gangue mineral was quartz, followed by calcite, feldspar and mica .

According to the ore nature of the sample, the sample belongs to the quartz-type fluorite ore with fine grain size. To ensure the quality of the fluorite concentrate, the flotation process with multiple selections of grinding and fluorite is selected. .

2, rough selection conditions test

The rough selection test procedure is shown in Figure 1. The pH adjuster is sodium carbonate, the inhibitor is made of water glass, and the collector is oleic acid.

(1) Rough grinding grinding fineness test

The grinding time is 1, 3, 5, 7 min, respectively, and the grinding fineness test results are shown in Fig. 2.

The rough selection conditions are: sodium carbonate 200g/t, water glass 100g/t, collector oleic acid 400g/t, flotation foaming time is 5min, rough roughing fineness test results are shown in Fig. 3.

It can be seen from Fig. 3 that as the fineness of the grinding increases, the grade of the coarsely selected concentrate remains basically unchanged, but the recovery rate gradually decreases. For quartz-type fluorite ore, because quartz has a higher hardness than fluorite, the stage grinding stage is very important for desiliconization. Therefore, rough selection is advantageous for desiliconization under coarser fineness conditions. The grinding time was 1 min, and the grinding fineness was -0.074 mm, accounting for 42.52%.

(2) Crude selection of sodium carbonate dosage test

The rough selection keeps the grinding time 1 min, the water glass is 400 g/t, the collector is 400 g/t, and the amount of sodium carbonate is changed. The test results are shown in Fig. 4.

It can be seen from Fig. 4 that as the amount of sodium carbonate increases, the grade of fluorite increases and the recovery rate decreases. When the amount of sodium carbonate reaches 400g/t, the grade reaches the maximum and the recovery rate is minimized, and then continues to increase. The amount of sodium carbonate, the grade of fluorite is reduced, and the recovery rate is increased. In order to meet the requirements of grade and recovery rate in the rough selection process, the amount of sodium carbonate was chosen to be 200g/t. At this time, the grade of crude fluorite concentrate was 76.33% and the recovery rate was 76.38%.

(3) Inhibitor species exploration test

Since the sample belongs to the quartz type fluorite ore, the quartz mass fraction is high, the quartz is easily activated by metal ions or enters the concentrate product due to foam entrainment, so it is necessary to select a suitable inhibitor for the flotation separation of fluorite and quartz. .

1 single inhibitor test

Inhibitor selected single sodium fluoride, citric acid, shuttle methylcellulose, sodium hexametaphosphate four kinds. The test results are shown in Table 1.

The experiment found that the effect of citric acid and sodium hexametaphosphate is relatively good, but the effect is not satisfactory in the test with water glass compounding, and the sodium hexametaphosphate has a strong inhibitory effect on fluorite in the later selected section. Not used.

2 water glass and inorganic agents test

After the water glass is mixed with several inorganic agents, the salified water glass or the oxidized water glass is prepared to investigate the effect of the water glass after the inorganic agent is added. The test results are shown in Table 2.

It can be seen from the test results that the combination of water glass and inorganic salt is not ideal for improving the flotation effect.

3 water glass and organic agent action test

The water glass was compounded with several organic agents shown in Table 3 to investigate the effect of the water glass after the organic agent was added. The test results are shown in Table 3.

It can be seen from Table 3 that after adding dextrin, the recovery rate of fluorite can be greatly improved without reducing the concentrate grade, and the grade of rough-selected fluorite concentrate is reduced from 76.33% to 71.53%, and the recovery rate is 76.38% increased to 95.63%, indicating that adding a certain amount of dextrin to the pulp has a good effect on improving the recovery rate of the coarse-choice fluorite concentrate, so the combination of water glass and dextrin is selected as the inhibitor.

(4) Collector dosage test

Grinding 1 min, sodium carbonate 200 g / t, water glass 400 g / t, dextrin 80 g / t, change the amount of collector, the test results are shown in Figure 5.

It can be seen from Fig. 5 that when the amount of collector increases, the grade of the concentrate changes little and the recovery rate changes greatly. When the dosage of the collector is 400g/t, the grade and recovery rate of the concentrate are high, so the catch is high. The dosage of the dosage is 400g/t. At this time, the crude fluorite concentrate grade was 71.53%, and the recovery rate was 95.63%.

3. Selected trials

(1) Fine 1 test

No fine agent is added during the flotation, and after a series of flotation tests, the empty self-medication system of Jing 1 is considered to be more effective for the subsequent selection of refined concentrate grades.

(2) Regrind time test

The flotation concentrate after the fine 1 enters the regrind mill. The purpose of "rough grinding-roughing" is to remove most of the quartz in the fluorite ore at a coarser particle size, because if the grinding particle size is too fine, the fine-grained quartz will enter the subsequent selection operation and it is difficult to remove. The purpose of "re-grinding-selection" is to fully dissociate the fine-grained fluorite single mineral and obtain flotation recovery. The results of the regrind time test are shown in Fig. 6.

It can be seen from the test results that the best effect is obtained when the regrind time is 2 min.

(3) Flotation full process open circuit test

The whole process of open circuit adopts 1 rough selection, 7 selections, fine 1 concentrate regrind process, and the pharmaceutical system is the same as Figure 7. The open circuit process test results are shown in Table 4.

It can be seen from Table 4 that using the open-circuit flotation process and the pharmaceutical system, concentrate products with a CaF2 grade of 97.31% and a recovery rate of 64.33% can be obtained.

(4) Flotation full-process closed-circuit test

By analyzing the open circuit test results, the closed-circuit whole process uses a 1 coarse 1 sweep 7 fine middle ore sequence return process. The closed circuit full flow chart is shown in Figure 7, and the closed circuit test results are shown in Table 5.

It can be seen from Table 5 that through the selected process flow and the pharmaceutical system, the final concentrate with a CaF2 grade of 96.45% and a recovery rate of 79.71% can be obtained, and the quality of the fluorite concentrate reaches the national first-class standard.

4 Conclusion

(1) The fluorite ore belongs to quartz-type low-grade fluorite ore. The main recoverable mineral is fluorite, the grade is 30%, the main gangue mineral is quartz, followed by calcite, feldspar and mica.

(2) According to the nature of the fluorite ore, through the systematic test of the coarse grinding time, the adjusting agent, the amount of the collector, especially the type of the inhibitor and the regrind time, the fineness of the rough grinding is determined to be - 200 mesh accounted for 42.52%, with water glass + dextrin as an inhibitor, oleic acid as a collector, using 1 coarse 1 sweep 7 fine, fine 1 concentrate re-grinding, closed loop process in the middle mine sequence, can get CaF2 grade 96.45%, a fluorite concentrate with a recovery rate of 79.71%.

(3) Through a single inhibitor test, the combination of water glass and inorganic inhibitors and the combination of water glass and organic inhibitors found that water glass and dextrin can be used as inhibitors without affecting the grade of fluorite concentrate. Under the premise, the recovery rate of rough fluorite is greatly improved.