Experimental Study on Beneficiation of Magnetic Red Limonite
Rapid economic development in China, leading to a huge demand for steel products. Iron ore is used as a raw material for iron making, and the development of its sorting technology is directly related to the utilization level of iron ore raw materials. As the easy-to-select ore decreases day by day, the development and utilization of ore that is difficult to select for small reserves is increasingly important.
The grade of an iron ore is 46.16%. The main iron-bearing minerals are magnetite and red limonite. The sulfur content of harmful elements is relatively high. It is treated by a single magnetic separation method. The weak magnetic red limonite is not effective. Use. In view of the nature of the mine, the study uses the grinding-weak magnetic separation-strong magnetic rough selection, coarse concentrate fine grinding selection-shaker cleaning process to obtain iron ore grade and iron recovery rate respectively: 64.73% and 16.51% of the magnetite concentrate, and the iron grade and iron recovery rate were 56.51% and 46.58% respectively, and the sulfur content of the two iron concentrates did not exceed the standard.
one. Ore nature
The results of multi-element analysis and iron phase analysis of ore minerals are shown in Table 1 and Table 2, respectively. It can be seen from Table 1 and Table 2 that the iron in the ore is mainly in the form of magnetite and red limonite (mostly red limonite), and the rest is a small amount of iron carbonate and pyrite.
According to Table 1, the content of harmful elements such as phosphorus and arsenic in raw ore is not high, all lower than 0.10%, but the high sulfur is 0.36%; according to the data in Table 2, the iron grade of ore iron sulfide is very low at 0.045%, so the sulfur in the raw ore is not From iron sulfide. The results of the ore spectrum analysis show that the strontium content of the ore is 0.40% higher; therefore, most of the sulphur in the ore may come from gangue mineral barite (BaSO4). Obviously, this sulfur can be removed by physical beneficiation .
two. Experimental research and results
1. Raw ore grinding fineness test The original ore is crushed to less than 2mm, and the magnetic induction strength of the magnetic separation tube is selected to be 0.15T. The grinding fineness test is carried out. The results are shown in Figure 1 below.
It can be seen from Fig. 1 that as the fineness of the grinding increases, the iron grade of the weak magnetic iron ore concentrate increases, and the iron recovery rate decreases; this is because the finer the ore grinding grain size, the more sufficient the iron mineral dissociation. Taking into account the practical feasibility of the production, the grinding fineness is -0.074mm, accounting for 90%, and the iron grade corresponding to the weak magnet concentrate is 65.71%.
2. The fineness of the ore weak magnetic separation test is -0.074mm, accounting for 90%, and the magnetic induction intensity of the iron concentrate index with weak magnetic separation is shown in Fig. 2. It can be seen that as the magnetic induction intensity increases, the grade of iron concentrate decreases and the yield of iron concentrate increases. Mainly consider the iron grade index of iron concentrate, the magnetic induction intensity of the weak ore selection of the original ore should be 0.15T.
3. Strong magnetic separation test of ore weak magnetic separation tailings From the iron phase analysis results of Table 2, the iron distribution rate of the red limonite in the ore is 75.65% of the total iron; therefore, the effective separation of such iron minerals It is a key factor in achieving effective separation of raw ore. For this type of iron mineral, apply SLon-100 periodic pulsating é«™ gradient permanent magnetic cylinder magnetic separator, fixed pulsating stroke 6mm and stroke 200r/min, select 2 mm rod magnetic medium, change background magnetic induction intensity, and perform high pulsation Gradient magnetic separation test, the results are shown in Figure 3.
It can be seen that as the intensity of the induction field increases, the iron grade of the iron concentrate decreases, exceeding 0.8T, the iron grade decreases significantly, and the iron recovery rate tends to be stable; obviously, the magnetic induction intensity of the ore high gradient magnetic separation should be selected 0.8T. At this time, the iron grade of the iron concentrate was 49.87%, and the iron recovery rate was 60.90%. Therefore, after removing the ferromagnetic magnetite by weak magnetic separation, only the iron concentrate with iron grade of about 50% can be obtained by gradient magnetic separation; the microscope of the iron concentrate is found to have low iron grade. The main reason is due to the existence of a large number of connected organisms. At the same time, the results of this test indicate that magnetite and chernorite in the ore have different monomer dissociation degrees.
4. High-grained strong magnetic coarse concentrate fine grinding selection test In order to obtain a higher iron grade red brown iron concentrate, the high-grade magnetic separation of the crude iron concentrate (fineness is -0.074mm, accounting for 91.37%) is fine. Grinding selected experimental studies, the results are shown in Figure 4 below.
The operating conditions of this test were selected to be a pulsating stroke of 6 mm, a pulsating stroke of 200 r/min, a 2 mm rod medium and a magnetic induction intensity of 0.8 t.
As shown in Figure 4, as the fineness of the grinding increases, the increase in iron concentrate grade and iron recovery rate is significantly slower, and the iron recovery rate is significantly reduced. Therefore, the fine grinding fine grain size should be controlled at -0.074mm, which is about 97%. At this time, the iron grade of iron concentrate increased from 49.87% to 55.86%, and the iron recovery rate was 39.95%. For iron-selected iron concentrates, microscopic observations have found that iron minerals have basically achieved monomer dissociation.
Therefore, fine coarse grinding of the coarse concentrate obtained by rough selection of é«™ gradient magnetic separation can significantly improve the index of iron concentrate. In order to further improve the selected index of the é«™ gradient magnetic separation, explore the best operating conditions, and carry out condition optimization experiments on the fine ore fine grinding selection operation. The results are shown in Table 3 below.
From the results of Table 3, the following two conclusions can be drawn: First, in order to ensure the iron recovery rate of the selected operation, the selected magnetic induction intensity should not be too low; instead, the work recovery rate of the 2 mm rod medium is higher than that of the 3 mm rod medium, although The iron concentrate grade is slightly higher. The operating conditions for selected operations should be selected from magnetic induction 0.8T and 2mm rod media.
5. High-gradient strong magnetic concentrate tailings re-election test
As can be seen from Table 3 above, the iron grade of the tailings in the high-gradient selection operation is relatively high, and the direct disposal as tailings will seriously affect the total iron recovery rate; therefore, in order to explore the possibility of further increasing the total iron recovery rate, The iron tailings obtained from the best high gradient selected operating conditions were subjected to a shaker sweep test. The test results show that the high-gradient selected iron tailings can be selected; the iron grade and the yield of iron-stained iron concentrates can be 52.76% and 3.58%, respectively, and the effect is obvious.
three. Recommended process flow and reelection test results
1. The process flow is to verify the feasibility of the above test in the actual production. The best operation parameters determined by the above various conditions are used to conduct the continuous selection test of the ore. The test flow is shown in Figure 5. The test results are shown in Table 4. In the re-election test, the high-gradient magnetic separation rough selection and the selective inspection all use 2mm rod media.
It can be seen from Table 4 that the ore is processed by the process flow of Figure 5, and the magnetite concentrate with iron grade and iron recovery rate of 64.73% and 16.51%, respectively, and the iron grade and iron recovery rate are 56.51% and 46.58%, respectively. Red brown iron concentrate. The analysis results of the two iron concentrates show that the content of sulfur, phosphorus and arsenic in the iron concentrate is 0.18%, 0.1% and 0.006% after the original ore treatment, and the contents of sulfur, phosphorus and arsenic in the red brown iron concentrate are respectively 0.20%, 0.04%, and 0.006%, while the content of sulfur, phosphorus and arsenic in the primary iron concentrate is less than 0.6%, 0.05% and 0.05%, so the harmful elements of the iron concentrate are not exceeded; On the one hand, it confirms the correctness of the previous analysis, on the other hand, it illustrates the practical feasibility of the process. This process provides a viable route for the sorting of the same type of iron ore.
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