The cyclone-static microbubble flotation column was developed by China University of Mining and Technology and won the second prize of the 2002 National Technology Invention. The main structure includes a column flotation section, a cyclone separation section, and a tube flow mineralization device. The whole equipment is the main part, and the column flotation section is located in the upper part of the column. It adopts the flotation principle of countercurrent collision mineralization, and realizes the sorting of fine materials in the static sorting environment of low floc flow, starting from the whole column sorting method. To rough selection and selection. The cyclone separation section and the column flotation section are connected to the upper and lower structures to form the main body of the column sorting method. Swirl sorting includes gravity separation by density and swirl flotation in the context of a swirling force field. Swirl flotation not only provides a highly efficient mineralization method, but also greatly reduces the lower limit of flotation particle size and greatly improves the flotation speed. Swirl sorting plays the role of sweeping the column flotation mine in the column sorting process with its strong recovery capacity. The tube flow mineralization device is connected to the swirling separation section along the tangential direction, and the middle ore is subjected to cyclic sorting. The pipe flow mineralization device utilizes the jet principle to form a gas-solid-liquid three-phase system of circulating minerals in the pipe flow by introducing a gas and pulverizing it into a bubble, and achieving high flocculation mineralization. The cyclone-static microbubble flotation column has the characteristics of stable operation, good sorting selectivity, high efficiency, large processing capacity, low power consumption and strong adaptability.
The cyclone-static microbubble flotation column has been used for the reverse flotation of a strong magnetic separation concentrate. Ore flotation column tests iron grade of 44.87% under the conditions of use of a roughing, once scavenging reverse flotation, fine mineral rate can be obtained 47.80%, 67.41% grade iron ore, the recovery rate of 71.52% Better indicator. Compared with the flotation machine, the recovery rate is increased by 8.37 percentage points when the ore grade and the concentrate grade are basically the same, and one rough selection, one concentrate, three sweeps when using the flotation machine The reverse flotation process has been greatly shortened.
In this study, the cyclone - static microbubble flotation column 42.00% iron mixed on a magnetic iron ore beneficiation plant to improve the anti-flotation concentrate grade small laboratory tests.
1. Samples and flotation reagents
(1) Samples and their properties
1. The sample is a mixed magnetic separation iron concentrate obtained from an iron ore beneficiation plant. The iron minerals are mainly hematite, magnetite and imaginary hematite, and the gangue mineral is mainly quartz . The main chemical composition of the sample is shown in Table 1, and the particle size analysis results are shown in Table 2.
Table 1 Main chemical composition of the sample
ingredient | TFe | SiO 2 | MgO | CaO | Al 2 O 3 |
content | 42.00 | 43.50 | 1.57 | 0.46 | 1.67 |
Table 2 Sample particle size analysis results
Size/mm | Yield/% | Iron grade /% | |
individual | Grand total | ||
+0.154 | 0.52 | 9.60 | 9.60 |
-0.154+0.090 | 7.89 | 9.91 | 9.89 |
-0.090+0.074 | 37.70 | 32.59 | 28.45 |
-0.074+0.053 | 7.10 | 35.62 | 29.41 |
-0.053 | 46.79 | 56.28 | 41.98 |
total | 100.00 | 41.98 | |
As can be seen from the results of the particle size analysis, the fineness of the sample was -0.074 mm, accounting for 53.89%. Microscopic observation shows that the iron mineral and quartz have been well dissociated under this fineness (see Figure 1), so no further grinding is required.
Figure 1 Mineral micrograph of different size samples
If the chart is unclear, you can call it for free.
2, flotation reagent
NaOH is used as a pulp conditioner. Adjust the pH of the slurry in the mixing tank to be 11.0~11.5.
Causticized starch is used as an inhibitor of iron minerals. When the causticized starch was placed, 20% NaOH was added, stirred at 90 ° C for 1 h, then cooled and diluted to 5% for testing.
Analytically pure CaO was used as an activator for quartz.
Saponified oleic acid is used as an anionic collector for iron minerals. Oleic acid was saponified by the addition of 20% NaOH, and saponified and diluted to 10% for testing.
Second, the test device
The laboratory type cyclone-static microbubble flotation column of ф70mm×1600mm and ф70mm×1400mm is used as the column flotation equipment . Both flotation columns are made of plexiglass tubes, the former for reverse flotation rough selection and the latter for reverse flotation sweep.
The flotation column test uses a 30L mixing tank as a mixing equipment, a pipeline pump is used as a mine circulation pump, and a peristaltic pump is used to control the ore and discharge flow.
4kg per sample for the flotation column test. The water was heated in a mixing tank to adjust the temperature, and the temperature was adjusted to 40 ° C.
The comparative test used a laboratory XDF type 0.75L flotation machine, each time using 200g, the flotation concentration was 30%.
Third, the test results and discussion
The same chemical system was adopted for the cyclone-static microbubble flotation column and flotation machine: NaOH dosage 0.9kg/t; causticized starch dosage 1.0kg/t, pulping 5min; CaO dosage 0.38kg/t, pulping 3min The amount of saponified oleic acid was 0.35 kg/t, and the slurry was slurried for 2 min.
(1) Comparison test of swirling-static microbubble flotation column and flotation machine
The rough sample was subjected to a rough selection test using an unmodified swirl-static microbubble flotation column (shown in Figure 2). The results are shown in Figure 3. In order to examine the test results, a comparison test was carried out using a flotation machine under the same pharmaceutical system, and the results are shown in Fig. 4.
Figure 2 Unswirl-static microbubble flotation column
Figure 3 Flotation column rough selection test results
â– -concentrate grade; â–½-tailing grade; â—‹-concentrate recovery rate
Figure 4 Flotation machine rough selection test results
â– -concentrate grade; â–½-tailing grade; â—‹-concentrate recovery rate
Compared with the flotation machine and the cyclone-static microbubble flotation column, the results of rough selection test show that under the same chemical conditions, the flotation machine concentrate grade and tailings grade are stable, and the concentrate recovery rate does not change much; With the vortex-static microbubble flotation column, the grade of tailings gradually increased with the passage of time, and the recovery rate of concentrate decreased sharply.
The concentrate grade of the cyclone-static microbubble flotation column averages about 67%, while the tailings grade averages about 25%. The average grade of flotation concentrate is only about 64%, and the tailing grade averages about 16%.
The concentrate grade of the cyclone-static microbubble flotation column is about 3 percentage points higher than the concentrate grade of the flotation machine. It can be seen that the cyclone-static microbubble flotation column is advantageous as a selective equipment.
(2) Swirling-static microbubble flotation column one coarse one closed circuit test
In order to solve the problem of high grade of roughing tailings in the cyclone-static microbubble flotation column, two cyclone-static microbubble flotation columns were used, and a coarse and one closed circuit test was carried out according to the flow of Fig. 5. The test was taken once at 5, 10, and 15 min, and the results are shown in Fig. 6.
Figure 5 Flotation column one rough one closed circuit test process
Figure 6 Flotation column one rough one closed circuit test results
â– -concentrate grade; â–½-tailing grade; â—‹-concentrate recovery rate
It can be seen from Fig. 6 that the cyclone-static microbubble flotation column is a coarse-sweep closed-circuit reverse flotation, the concentrate grade reaches about 68%, the tailings grade drops below 12%, and the recovery rate is above 85%. Obviously, it is proved that the cyclone-static microbubble flotation column can well realize the selection of low-grade mixed magnetic separation iron concentrate in an iron ore dressing plant.
(3) The rough selection effect of the swirling-static microbubble flotation column after the mine mouth is moved down
In order to reduce and stabilize the rough-selected tailings grade of the cyclone-static microbubble flotation column, the structure of the flotation column was modified, that is, the feeding port of the flotation column was moved down, using the feeding port shown in Figure 7. 2 to the mine. The rough selection effect of the swirl-static microbubble flotation column after the mine is moved down is shown in Fig. 8.
Figure 7 Improved swirl-static microbubble flotation column
Fig. 8 Results of rough selection test after the flotation column is moved down to the mine mouth
â– -concentrate grade; â–½-tailing grade; â—‹-concentrate recovery rate
It can be seen from Fig. 8 that the downward transfer to the ore port does not reduce the grade of the rough-selected tailings of the cyclone-static microbubble flotation column, but the flotation process is unstable. The reason may be that the downward movement of the ore mouth shortens the reverse contact mineralization time of the slurry and the rising bubble, and reduces the probability of contact between the slurry and the rising bubble.
(4) The rough selection effect of the swirling-static microbubble flotation column after increasing the pulsating magnetic field
Since the test ore sample contains a certain amount of ferromagnetic iron minerals, a pulsating magnetic field device is added to the cyclone-static microbubble flotation column to make the cyclone-static microbubble flotation column in the original gravity, buoyancy and Based on the action of the cyclone field, the magnetic force is further increased to achieve better separation of the iron mineral and the gangue mineral. The pulsating magnetic system includes two sets of excitation coils and a set of intermediate demagnetization coils, a schematic view of which is shown in FIG.
Under the action of the magnetic field formed by the upper excitation coil, the magnetic agglomeration of the ferromagnetic minerals in the slurry will occur; the magnetic agglomerates will be moved by the magnetic force from the center of the cylinder to the excitation coil, and at the same time, due to the growth of the magnetic agglomeration coil, under the action of gravity Lower movement; after the demagnetization coil in the middle, the agglomeration is opened, the ore is loose, and the gangue mineral originally mixed in the agglomeration rises under the action of the rising swirl, and the magnetic mineral continues to descend after passing through the lower excitation coil. , magnetic agglomeration is formed again, and finally enters the cyclone separation zone under the action of magnetic force to be recovered.
The results of the rough selection test after the swirling-static microbubble flotation column increases the pulsating magnetic field are shown in Fig. 9. It can be seen that under the action of the pulsating magnetic field, the grade of the rough-selected tailings has a large decrease, but the grade of the concentrate is unstable.
Figure 9 Rough selection test results after the flotation column increases the pulsating magnetic field
â– -concentrate grade; â–½-tailing grade; â—‹-concentrate recovery rate
(5) The swirling-static microbubble flotation column keeps the concentrate grade stable while reducing the grade of the tailings, and increases the pulsating magnetic field and adds the steady flow tube shown in Fig. 7. The results of the rough selection test after increasing the pulsating magnetic field and the steady flow tube are shown in FIG.
Figure 10 Rough selection test results after the flotation column simultaneously increases the pulsating magnetic field and the steady flow tube
It can be seen from Fig. 10 that after the vortex-static microbubble flotation column increases the pulsating magnetic field and the steady flow tube, the average grade of the coarsely selected concentrate reaches 67.85%, and the average grade of the tailings falls to 16.45%. The average recovery rate of the concentrate is 79.22%, compared with the rough selection index of flotation machine, the average grade of tailings is close, the average grade of concentrate is increased by nearly 4 percentage points, and the selection index is relatively stable, and the results are satisfactory.
(6) Flotation machine one rough and one fine sweep open circuit test
In order to better compare the improved cyclone-static microbubble flotation column with the flotation machine, a coarse and fine sweep open circuit test of the flotation machine was carried out according to the flow of FIG. The test results are shown in Table 3.
Figure 11 Flotation machine a rough one fine sweep open circuit test process
Table 3 Flotation machine one rough and one fine sweep open circuit test results
product | Yield | grade | Recovery rate |
Concentrate | 49.13 | 68.04 | 79.92 |
Selected tailings | 13.87 | 25.54 | 8.47 |
Sweeping concentrate | 9.63 | 17.14 | 3.95 |
Tailings | 27.36 | 15.79 | 10.33 |
Feed mine | 100.00 | 41.83 | 100.00 |
Comparing the test data of Table 3 and Figure 10, it can be seen that the flotation machine needs to pass the index of one coarse and one fine sweep three times to select the index. The improved swirl-static microbubble flotation column only needs to pass one coarse The choice can be basically achieved.
Fourth, the conclusion
(1) Reverse-flotation of a low-grade magnetically-selected iron concentrate with a cyclone-static microbubble flotation column. The crude ore grade can reach about 67% with one rough selection, but the tailings grade is higher.
(2) After adding a pulsating magnetic system to the cyclone-static microbubble flotation column, the cyclone-static microbubble flotation column can further increase the magnetic force on the basis of the original gravity, buoyancy and swirling flow fields, thereby Effectively reduce tailings grade.
(3) Adding a steady flow tube to the cyclone-static microbubble flotation column, the equipment can be divided into two distinct areas: the static reverse contact mineralization in the upper part and the cyclone strengthening separation in the lower part, which stabilizes the sorting process. And the role of indicators.
(IV) After the improvement of the vortex-static microbubble flotation column through the addition of the pulsating magnetic system and the steady flow tube, not only the concentrate grade is high, but also the grade of the tailings is greatly reduced. Therefore, compared with the flotation machine, the improved swirl-static microbubble flotation column can reduce the number of operations and simplify the process structure when the similar selection index is obtained.
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