Mixed iron ore beneficiation process and experimental study

If a mixed miners in western China by the magnetic iron ore and hematite, limonite and composition of ore grade of 26.32%, the grinding fineness can reach -0.043mm95% iron concentrate grade of greater than 60% of the mixed ore The multi-element analysis of raw ore and the analysis of the original mineral phase are shown in Tables 1 and 2.

It can be seen from the above Tables 1 and 2. The main element that can be recovered from the ore is iron. The ore acidity basic coefficient is 0.09<1, which is an acidic ore. The harmful element sulfur is not high, and the phosphorus content is 0.22%. The main mineral ore metal is red, and magnetite, limonite, while a small amount of iron silicate, iron carbonate and iron sulfide. The iron minerals recovered from ore dressing are mainly red, limonite and magnetite, and take into account the recovery of other useful iron minerals.

First, the mineral composition of the ore

The main mineral composition of the ore is identified in Table 3 below.

The ore is grayish black, dark brown, and has a fine structure. The iron minerals in the ore are mainly magnetite, followed by hematite and limonite. The content of metal sulfide minerals is very low, occasionally the sporadic distribution of pyrite, the gangue minerals are mostly quartz , followed by chlorite, iron dolomite, calcite and apatite, and other traces of two violent spurs, zircon , attapulgite, monazite, rutile and vermiculite.

Second, the beneficiation process and test

The above ore is a mixed type of iron or hematite iron ore. The useful minerals in the ore are mainly red, limonite and magnetite. The main impurity in the ore is SiO2. We should first consider low-field magnetic separation to obtain qualified iron concentrates as much as possible, and then recover the iron in the tailings by strong magnetic separation or re-election. According to the nature and characteristics of the ore, we should first consider the magnetic separation (weak magnetic separation - strong magnetic separation) of the different fineness of the ore in the ore dressing. Different ore fine grain size, strong magnetic separation concentrate re-election (shaker) sorting and different ore-concentrating particle size strong magnetic concentrate reverse flotation, and then based on the selected results to determine the reasonable selection process of the ore.

1. Magnetic separation of different grinding sizes of raw ore

Grinding fineness is based on the grinding particle size curve. The magnetic separation and selection of different grinding fineness products is combined with the index balance of iron concentrate to determine the fineness of grinding. The ore is ground to a different particle size by a ball mill to carry out magnetic separation beneficiation of different grinding sizes. First, weak magnetic separation is performed. The magnetic separation process is 1 coarse and 1 fine, and the magnetic separation condition is rough magnetic field strength 159.24KA/m, rising. The water volume is 15 mL/s; the selected magnetic field strength is 95.54 kA/m, and the rising water volume is 20 mL/s. We obtained the weak magnetic rough-choice tailings and then carried out strong magnetic separation. The beneficiation process was 1 rough selection. The ore-making conditions were magnetic field strength 796.18kA/m and concentrate rinsing water volume 300mL/s. The results are shown in Table 4 below:

We can see from the results in Table 4 above: as the fineness of grinding increases, the yield of concentrate obtained by weak magnetic separation and strong magnetic separation decreases, and the grade of concentrate iron increases, when the original ore is milled to - 0.038mm99% (-0.030mm95%), the yield can be obtained is 14.75%, the iron grade is 62.11% weak magnet concentrate, and the iron grade is 40.92% strong magnetic concentrate, which can be seen. The size of the inlay is very fine. To obtain a higher grade iron concentrate, it must be finely ground with a superfine ball mill.

2, strong magnetic rough selection iron concentrate strong magnetic selection

We can carry out the strong magnetic selection test of the strong magnetic concentrate obtained from the ore grinding grain size 10.043mm95% magnetic separation in Table 4 above. The test conditions are strong magnetic selection magnetic field strength 238.85kA/m, concentrate rinsing water volume 400mLs The test results can be derived from Table 5 below:

From the results in Table 5, we can see that the ore concentrate ore grinding grain size is -0.043mm95% of the strong magnetic rough selection concentrate for strong magnetic selection, even if the strong magnetic selection magnetic field strength is reduced to 238.85kA / m, Only the concentrate grade can be increased by 1.82 percentage points. It can be seen that the ore is only sorted by a single magnetic separation process, and the sorting effect is not good.

3, the original ore different grinding grain size strong magnetic concentrate re-election (shaker) selection

From the strong magnetic concentrate obtained from the magnetic separation test of different ore grinding sizes in the above table 5, the re-election (shaker) selection test was carried out, and the test results are shown in Table 6 below. Sorting principle flow chart 1.

It can be seen from the test results in Table 6 above that as the fineness of grinding increases, the yield of concentrate obtained by re-election (shaker) decreases, the grade of concentrate iron increases, and the enrichment ratio decreases, indicating that fine grinding makes minerals sufficient. The dissociation contributes to the improvement of the grade of the iron concentrate, but the grinding particle size is too fine, and the effect of the re-election sorting deteriorates, which is mainly due to the fact that the re-election is selected by the lower limit of the particle size.

4, the original ore different grinding grain size strong magnetic concentrate reverse flotation

The anti-flotation beneficiation process technology is one of the effective methods for improving the quality of iron ore. The strong magnetic concentrate obtained from the magnetic separation test of different ore-grown particle sizes in the above table 4 is the object of reverse flotation test. The test procedure is 1 coarse 2 Fine, the test conditions are rough selection: NaOH 1000g / t, starch (referred to as DF, the same below) 1000g / t, CaO 300g / t, collector 2 #300g / t.

1 selection: M1 100g/t, 2 selections: M1 50g/t. Flotation time: 5 min for rough selection, 3 min for 1 time, 2 min for 2 times, and the test results are shown in Table 7 below.

We can see from the test results in Table 7 above that the ore strong magnetic concentrate can be significantly improved by reverse flotation, and when the grinding particle size is -0.076mm99% (-0.043mm90%), An iron concentrate with a yield of 26.32% (6.25% for ore) and an iron grade of 58.35% can be obtained. It can be seen that the ore strong magnetic concentrate is effectively selected by a reverse flotation process.

Note: After the stage grinding, weak magnetic separation, strong magnetic separation and reverse flotation process, the iron ore can obtain the concentrate yield of 2.47% and the iron grade of 61.5 under the condition of final grinding particle size of -0.043mm90%. %, the iron recovery rate of 47.01 is the selection indicator, the process and indicators are shown in Figure 2 below:

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