Experimental study on beneficiation of a scheelite

The main tungsten mineral of a scheelite deposit is scheelite, containing a small amount of black tungsten ore and very few sulfide minerals. The content of high calcium gangue fluorite and calcite in the original ore is extremely high, which has a certain influence on the flotation recovery of tungsten. According to the mineral composition of ore and the grain size of tungsten minerals, this study used coarse grain re-election, re-selected the ore and tailings and re-grinded with fine mud to carry out flotation process to recover tungsten minerals, and obtained good test results.

    First, the nature of the ore

The main tungsten mineral in the ore is scheelite and contains a small amount of black tungsten ore. Few sulfide minerals, there are pyrite, yellow copper ore, galena like. Content of the gangue minerals of fluorite large, comprehensive utilization; other gangue minerals are sericite, calcite. The results of multi-element analysis and original mineral phase analysis of raw ore are shown in Tables 1 and 2, respectively.

Table 1 Multi-element analysis results of raw ore %

Table 2 Analysis results of tungsten ore phase of ore

The results of process mineralogical studies show that the main fraction of scheelite in ore ranges from 0.02 to 0.32 mm, and the size of wolframite concentrates above 0.04 mm.

Second, the determination of the principle process

This test only considers the recovery of tungsten in the ore. In view of the large difference in density between tungsten minerals and gangue minerals, and the relatively large particle size of tungsten minerals, it is determined that the coarse-grained tungsten minerals are first recovered by re-election under coarse grinding conditions, and the resulting re-selected ore and tail are produced. The ore is re-milled and combined with fine mud to recover fine-grained tungsten minerals by flotation.

    Third, re-election test

Choosing a reasonable re-election equipment is the key to ensuring the efficiency and economic indicators of re-election operations. The spiral concentrator and spiral chute have the characteristics of large processing capacity, high concentration of ore, small floor space, no moving parts of the equipment itself, easy operation, etc., and are often used as roughing equipment. The shaker has the characteristics of high sorting precision, but the processing capacity is small and the floor space is large. Therefore, it is often used as a selection equipment in combination with a spiral concentrator and a spiral chute.

For the ore, the -0.2+0.074mm fraction is coarsely selected and swept by the GL spiral concentrator, and the obtained coarse concentrate is selected by a shaker; the spiral concentrator sweeps the selected ore and the shaker tailings to select the tungsten minerals. The main body is the main body, and they are reground and then re-selected with a shaker. The -0.074mm size is selected by spiral chute for rough selection and medium ore re-election, and the obtained coarse concentrate is selected by micro-grain shaker. The re-election test procedure is shown in Figure 1, and the test results are shown in Table 3. It can be seen from Table 3 that after re-election, most of the tungsten in the ore has been effectively recovered.

Figure 1 re-election test process

Table 3 Re-election test results %

    Fourth, flotation test

(1) Normal temperature flotation test

1. Grinding fineness test

The tungsten minerals in the fine mud produced by re-election have basically dissociated all the monomers, and the dissociation of the tungsten minerals contained in the re-selected ore and tailings is not complete enough. Therefore, it is necessary to re-select the ore and tailings after grinding. Combined with fine mud as a feed for flotation. The grinding test procedure and conditions are shown in Figure 2, and the test results are shown in Figure 3. It can be seen that the WO ₃ grade and recovery rate of the coarse concentrate first increased with the increase of grinding fineness, but when the grinding exceeded -0.074 mm accounted for 85%, the WO ₃ grade decreased sharply. It was therefore determined that the re-selected ore and tailings were ground to -0.074 mm for 85%.

Figure 2 Grinding fineness test process and conditions

Figure 3 Grinding fineness test results

□-grade; ●-recovery rate

2, coarse selection of NaOH dosage test

The use of NaOH as a slurry medium regulator, the pH is controlled between 9 and 10, which is beneficial to the flotation of tungsten minerals. According to the flow of Figure 2, the coarsening NaOH dosage test is carried out under the condition of re-selecting the ore and tailings grinding fineness of -0.074mm, 85%, water glass dosage of 3000g/t, and FW2 dosage of 50g/t. 2 is shown. It can be seen that with the increase of the amount of NaOH, the grade of WO _{3 in the} coarse concentrate increases and the recovery rate decreases. Considering comprehensively, it is determined that the amount of coarsely selected NaOH is 1500 g/t.

Figure 4 Test results of NaOH dosage in normal temperature flotation

□-grade; ●-recovery rate

3, rough selection of water glass dosage test

In the flotation of tungsten ore, water glass is usually used as an inhibitor of gangue such as fluorite and calcite. The amount of water glass is too low to effectively suppress the gangue; if the amount is too high, the tungsten mineral will also be inhibited. Therefore, it is very important to choose the right amount of water glass. According to the flow of Figure 2, in the re-election of the ore and tailings grinding fineness of -0.074mm accounted for 85%, NaOH dosage of 1500g / t, FW2 dosage of 50g / t, the crude water glass dosage test is carried out, the results are shown in the figure 5 is shown. It can be seen that as the amount of water glass increases, the grade of WO _{3 in} coarse concentrate increases and the recovery rate decreases. Considering comprehensively, the amount of coarsely selected water glass is determined to be 3000 g/t.

Figure 5 Test results of coarse water flotation in normal temperature flotation

□-grade; ●-recovery rate

4, rough selection of collector FW2 dosage test

FW2 Guangzhou Research Institute of Nonferrous metal tungsten ore efficient collector. According to the flow of Figure 2, the rough selection FW2 dosage test was carried out under the condition of re-selecting the ore and tailings grinding fineness of -0.074mm, 85%, NaOH dosage of 1500g/t, and water glass dosage of 3000g/t. 6 is shown. It can be seen that as the amount of FW2 is increased, the recovery rate of WO _{3 in} coarse concentrate increases and the grade decreases. Considering comprehensively, it is determined that the amount of crude FW2 is 50g/t.

Fig. 6 Test results of rough selection FW2 dosage at normal temperature flotation

□-grade; ●-recovery rate

5, normal temperature flotation closed circuit test

On the basis of the conditional test and the open circuit test, the normal temperature flotation closed circuit test was carried out on the re-selected mine, tailings and fine mud. The test procedure and conditions are shown in Figure 7. The test results are shown in Table 4. It can be seen from Table 4 that due to the interference of calcium-containing gangue minerals such as fluorite and calcite, a qualified flotation concentrate cannot be obtained at normal temperature.

Figure 7 Normal temperature flotation closed circuit test process and conditions

Table 4 Results of closed-circuit test at room temperature flotation %

(2) Heating flotation test of normal temperature flotation concentrate

1. Heating flotation water glass dosage test

The normal temperature flotation concentrate still contains more fine-grained fluorite, calcite and other calcium-containing gangue minerals, and its floatability is close to that of scheelite, and the separation is very difficult. The research found that under the condition of adding water glass and high temperature, high concentration and high stirring strength, the planktonic properties of scheelite are much better than those of calcium-containing gangue minerals. Good floating tungsten indicator. According to the test, the temperature of the slurry is controlled at 90 °C, and the effect of mixing for 1 h or so is better. Under this condition, the water glass dosage test was carried out according to the flow of Fig. 8, and the test results are shown in Fig. 9. According to the results of Fig. 9, it is determined that the amount of the heated flotation water glass is 3500 g/t, and at this time, the flotation concentrate WO ₃ can be made 66% or more.

Figure 8 Test procedure and conditions for heating flotation water glass

Figure 9 Test results of heated flotation water glass

□-grade; ●-recovery rate

2, heating flotation closed circuit test

On the basis of the water glass dosage test, the heating flotation closed circuit test was carried out. The test procedure and conditions are shown in Figure 10. The test results are shown in Table 5. Table 5 shows that the warm flotation can make the flotation concentrate WO ₃ grade reach 66.70%, and the operation recovery rate is 94.82%.

Figure 10 Heating flotation closed circuit test process and conditions

Table 5 Heating Flotation Closed Circuit Test Results %

    V. Full process test

The whole process and conditions of the re-election-flotation test are shown in Figure 11, and the test results are shown in Table 6. It can be seen that the process of recovering coarse-grained tungsten ore by re-election method under rough grinding conditions and recovering fine-grained tungsten ore under normal-temperature flotation-heating flotation method under fine grinding conditions has achieved very good beneficiation index: The re-election concentrate WO ₃ grade is 68.93%, the recovery rate is 82.71%; the flotation concentrate WO ₃ grade is 66.70%, the recovery rate is 9.34%; the comprehensive concentrate WO ₃ grade and recovery rate are as high as 68.70% and 92.05% respectively. .

Figure 11 Re-election-flotation process and conditions

Table 6 Full Process Test Results %

    Conclusion

(1) For a scheelite ore rich in high calcium gangue, it is first re-selected with GL spiral concentrator, spiral chute and shaker under rough grinding conditions, and the WO ₃ grade can be obtained at a low cost of 68.93%. The rate is 82.71% of coarse concentrate.

(2) Re-selecting the ore and tailings after re-grinding and mixing with fine mud, using high-efficiency new collector FW2 for normal temperature flotation, and then by heating flotation, the WO ₃ grade is 66.70%, and the recovery rate is 9.34%. Fine-grain concentrate.

(III) The whole process integrated concentrate WO ₃ grade and recovery rate is as high as 68.70% and 92.05%, which provides a new way for the development and utilization of high calcium gangue scheelite resources.