New technology for iron reduction and silicon reduction in FCSMC flotation column

Lifting iron and reducing silicon is an important research content of China's mineral processing industry. Flotation columns have been widely used abroad to purify iron concentrates, while China is still the dominant flotation machine, and research on the anti-flotation of iron concentrate flotation columns is still in its infancy. The Changchang Group Gongchangling Concentrator is the first large-scale selection plant for the separation of magnetite by cationic reverse flotation. After more than two years of operation practice, the cationic reverse flotation foam is sticky and the flotation process is not smooth. As a problem that restricts production indicators and economic benefits, in order to obtain high-quality iron concentrates, improve economic efficiency and mineral processing technology , Angang Group Gongchangling Mining Co., Ltd. selects flotation columns as high-efficiency selection equipment for magnet concentrates. In the industrial test, advanced grades with iron concentrate grade higher than 69% and SiO ₂ content lower than 4.5% were obtained.

First, the flotation column structure and working principle

FCSMC flotation column is mainly composed of column flotation, cyclone sorting and tube flow mineralization. The sorting principle is shown in Figure 1. The whole equipment is a cylinder, and the column flotation 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 low turbulence static sorting environment, in the whole column sorting method. It plays a role of rough selection and selection; the cyclone separation and column flotation are connected to the upper and lower structures to form the main body of column sorting. Swirl sorting includes gravity separation by density and swirl flotation in the context of a swirling force field. Swirl flotation not only provides a high-efficiency mineralization reaction mode, but also greatly reduces the lower limit of flotation particle size and greatly increases the flotation speed. Swirl sorting plays the role of sweeping the column flotation mine in the column sorting process with its strong recovery capacity. Pipeline mineralization utilizes the jet principle to form a gas-solid-liquid three-phase system of circulating minerals in the pipe flow by introducing gas and pulverizing into bubbles, and achieving highly turbulent mineralization. Pipeline mineralization is connected along the tangential direction to the cyclone separation to form a cyclical separation of the middle ore.

Figure 1 FCSMC flotation column sorting principle

Second, the nature of the ore

The industrial test ore sample is from the fine sieve of the Gongchangling Concentrator. The grade of TFe is 63.63%, the content of SiO _{2 is} 10.51%, and the content of TFe ₃ O _{4 is} above 90%. As the particle size became finer, the iron content increased, and the grade of -0.030 mm grade iron reached 66.54%. The dissociation degree of the ore sample monomer is 92.7%, and the dissociation degree of the monomer of +0.074mm is also 87.9%, and the dissociation effect of the ore sample is ideal. The test can represent normal production samples in terms of fineness and monomer dissociation. The results of the determination of the size of the ore sample and the degree of dissociation of the monomer are shown in Tables 1 and 2.

Table 1 Results of particle size measurement

Table 2 Results of determination of dissociation degree of mineral sample

Third, the process

(1) Flotation machine beneficiation process

The magnetite ore in the Gongchangling mining area belongs to the Anshan-type sedimentary metamorphic iron deposit. The useful minerals are mainly magnetite and pseudo-hematite. The gangue minerals are mainly quartz , followed by actinolite, hornblende and chlorite. The separation plant of the ore dressing flotation flotation machine is a five-stage rough selection four-stage selection of a total of nine stages of reverse flotation, rough selection of mineral foam re-selection process, and the anti-flotation agent is dodecylamine. Add more medicine.

The on-site flotation machine selection process is shown in Figure 2. The sieved concentrate in the magnetic separation workshop is concentrated, pumped to the flotation tank, added to the collector, and then fed into the mixing tank. After fully mixing, it is fed into three series of 27 BF-20 coarse flotation machines. After the scrape is scraped out of the foam, more than 68% of the concentrate containing iron is flowed to the concentrate pump box and pumped to the filtration workshop for dewatering. The coarsely selected foam is pumped to a selected magnetic separator. After a fine sweep and tailing concentration, the concentrate is fed to the ball mill for further grinding. The grinding product is pumped to the dewatering tank and thrown. After the tail, the concentrate is further thrown into the second-stage magnetic separator. After further tailing, the second-stage magnetic separator concentrate is returned to the flotation machine for re-selection by the mine pump. The selected scraped medium-mine foam is directly returned to the ore tank for re-election through the fine tailing mine pump. The tailings produced by a sweeping magnetic separator, dewatering tank and two-stage magnetic separator are fed into the disc magnetic separator for further tailings recovery. A part of the concentrate is pumped to a magnetic separator for further grinding, and part of the self-flow After being fed into the ball mill and re-grinding, the tailings are fed to the thickener and concentrated.

Figure 2 Flotation machine process

The main problems of the sorting system are: 1 the number of selected sections is large, the equipment covers a large area, and the auxiliary operations such as magnetic separation, grinding, and dewatering tanks make the flotation process complicated and the running cost high; As a reverse flotation collector, dodecylamine has a poor foam sticking and flotation process, which affects the smoothing and sorting effect of the process.

(II) Selection of industrial test process for flotation column

The selection of the industrial test procedure for the flotation column is based on the semi-industrial split test. The main body sorting system adopts one-time rough selection of flotation column and two-stage sweeping process. After sweeping the selected ore, it returns to the pre-sorting slurry mixing barrel to form the internal circulation of the selected ore, and the coarse-concentrated concentrate is used as the final flotation. The concentrate, the second-stage sweeping tailings and the magnetic separator tailings are combined as the final tailings, as shown in Figure 3.

Figure 3 Flotation column process

As the sole source of power, each flotation column is equipped with a slurry pump. The foam transfer and transport are no longer used for reloading in the pump pool. The foam suction conveying mode is adopted, that is, the flotation foam of the front flotation column is used in the flotation process by using the foam suction conveying device installed inside the subsequent flotation column. The suction column is sucked into the rear stage, and the feeding of the subsequent flotation column is carried out, which does not affect the slurry flow state inside the equipment, improves the flotation operation environment, and optimizes the sorting index.

The column sorting system has several advantages: 1 configuration system stream is simplified, simple configuration, self-contained foam tank, bottom load bearing support, easy to install. 2 large processing capacity, low power consumption. 3 Sorting selectivity is good and efficiency is high. 4 equipment operation is simple and stable, and the index fluctuation is small. In addition to pump accidents, equipment maintenance is low. 5 Flotation foam suction conveying, the process is antegrade, the arrangement is simple, solves the problem that the cationic foam is sticky, and the middle mine is antegrade and enriched. 6 underflow drainage automatic control. The use of pressure sensor → digital display → electronic control valve closed circuit control, can achieve stable control of the liquid level, while leaving a remote control interface, can achieve centralized control.

(3) Industrial test methods

The industrial test was carried out in the flotation workshop of the ore dressing plant of Gongchangling Mining Company of Anshan Iron and Steel Group Co., Ltd., and the incoming material was the fine sieve and sieved product of the selected workshop. The product was concentrated by the thickener and pumped to the 1 and 3 series of distribution bins. The industrial test flotation feedstock is the same as the on-site flotation machine. The welded pipe at the bottom of the distribution bin is directly fed into the slurry mixing tank in front of the flotation column after being controlled by the valve. Therefore, the change in the feed properties of the test is consistent with the actual production. The iron grade generally varies between 63% and 65%, and the SiO ₂ content varies between 10% and 12%. The individual maximum iron grade is 67% and the lowest is 61%. The fineness of the ore-0.074mm is generally 88% to 90%. In order to avoid the influence of incoming material fluctuation on the flotation column sorting system, the flotation column feed concentration, the ore amount and the dosing method are automatically controlled. The concentrator is responsible for the test sample collection and laboratory work. The sample mainly analyzes the grade of iron.

Fourth, industrial test results and comments

(1) Effect of the dosage of dodecylamine on the sorting effect of flotation column

The effect of the amount of dodecylamine on the sorting effect of the flotation column is shown in Figure 4. It can be seen from Fig. 4 that with the increase of the amount of dodecylamine, the recovery rate shows a downward trend, and the TFe grade begins to increase. When the dosage of the agent reaches 180g/t, the grade of the concentrate increases gradually. When the dosage is changed between 160 and 180 g/t, the sorting advantage is more obvious, and the concentrate grade and recovery rate are at a higher level.

Figure 4 Effect of dodecylamine dosage on sorting index

(2) Effect of circulating slurry pressure on the selection of flotation column

The circulating slurry pressure is an important working parameter for the flotation column to improve the sorting efficiency and strengthen the sorting and recovery. It indirectly reflects the strength of the swirling force field at the bottom of the flotation column and the amount of circulating slurry. It is also the realization of the flotation column on the mineral. The only source of energy for sorting, the magnitude of the pressure is directly related to the operating state of the entire device and the sorting effect. Since the operation state of the rough-selected flotation column is directly related to the quality of the iron concentrate, for this reason, the influence of the rough-sorting slurry pressure on the sorting index is specifically examined in the test, and the results are shown in Fig. 5. It can be clearly seen from Fig. 5 that as the pressure increases, the TFe grade shows an upward trend. When the pressure exceeds 0.30 MPa, the change in the grade is not large. Therefore, the pressure of the circulating slurry during operation should be adequate to meet the principle of sorting swirl strength and appropriate inspiratory capacity.

Figure 5 Effect of cyclic slurry pressure on sorting index

(III) Influence of slurry concentration on the selection of flotation column

The effect of slurry concentration on the sorting effect of the flotation column is shown in Figure 6. It can be seen from Fig. 6 that the too low slurry concentration is not conducive to the recovery of iron, but when the concentration of the ore is too high, the resistance of the bubbles passing through the recovery zone is correspondingly increased, and the rise of the bubbles is difficult, resulting in a decrease in the TFe grade. When the concentration reaches a suitable level, the concentration of the ore is increased, and the recovery rate shows a downward trend. When the ore concentration is 40% to 45%, the technical index is better.

Figure 6 Effect of slurry concentration on sorting index

(4) Influence of ore supply on the selection of flotation column

The effect of the ore supply on the sorting effect of the flotation column is shown in Fig. 7. It can be seen from Fig. 7 that as the processing capacity increases, the concentrate grade gradually decreases and the recovery rate increases. When the system processing capacity is around 70t/h, the comprehensive sorting index is relatively good. This indicator fully meets the 65t/h processing capacity expected by the system design.

Figure 7 Effect of ore processing capacity on sorting indicators

V. Comparison of sorting indexes between flotation column and flotation machine

The flotation column industrial test system adopts FCSMC flotation column of Φ3.6m, Φ3.0m and Φ2.6m3 to form a cation full-process reverse flotation process for magnetic separation and concentration in a coarse two-sweep. Compared with the one-and-a-half-finishing of the flotation machine production system and the re-grinding magnetic separation and tailings recovery process, the process is greatly simplified. Through industrial tests, when the ore processing capacity is 70.61 t / h, the grinding particle size is -0.074 mm, the grain size is 89.30%, and the iron grade is 63.59%, the concentrate iron grade is 69.15%, and the SiO ₂ content is 4.40%. The tailings iron grade is 22.37%, and the iron recovery rate is 95.81%. Compared with the production index of flotation column, when the concentrate grade is basically the same, the concentrate yield is increased by 1.27 percentage points, the recovery rate is increased by 1.27 percentage points, the first grade grade is increased by 2.13 percentage points, and the pass rate is increased by 2.28 percentage points; The recovery machine feed (flotation machine tailings) grade is 11.78 percentage points lower than the final tailings of the recovery machine by 4 percentage points. The comparison of sorting results is shown in Table 3.

Table 3 Comparison of sorting indexes between flotation column and flotation machine industrial system

Conclusion

(1) Using the flotation column to sort the Gongchangling magnetite, a high-quality iron concentrate with an iron grade of 69.15%, a SiO ₂ content of 4.40% and an iron recovery rate of 95.81% can be obtained. The ideal industrial test operating parameters are: The dosage of diamine agent is 160-180g/t, the pressure of crude selective circulating slurry is 0.30MPa, the concentration of slurry is 40%~45%, and the processing capacity is about 70t/h.

(2) Using the flotation column-rough two-sweeping process, the cation collector can be used to purify the magnet concentrate and the middle mine, and the five sections of the existing flotation machine are selected and coarsely selected. regrinding and re-election process is the same, the rate of fine mineral flotation column increase 1.27 percent, ferrous metals recovery increased 1.27 percentage points, a product rate increased 2.13 percentage points, the pass rate increased by 2.28 percentage points; tailings grade than The tailings grade of the flotation machine is 11.78 percentage points lower than the tailings grade of the recovery machine by 4 percentage points.