The rapid development of my country’s economy has led to a huge demand for steel products. Iron ore is used as a material for iron smelting, and the development of its sorting skills is directly related to the level of use of iron ore materials. With the daily reduction of ore that is simply selected, the development and use of ore with small reserves and difficult to select becomes increasingly important.
The grade of a certain iron ore is 46.16%. The main iron-bearing ore deposits are magnetite and hematite. The harmful element sulfur content is relatively high. A single magnetic separation method is used for processing, during which the weakly magnetic hematite cannot be used. usage of. According to the nature of the ore, this study selects the process flow of grinding-weak magnetic separation-strong magnetic roughing, coarse concentrate fine grinding and selection-shaking table sweeping, and the iron ore grade and iron recovery rate can be separated as follows: The magnetite concentrates of 64.73% and 16.51%, and the hematite concentrates of 56.51% and 46.58% of iron grade and 46.58% respectively, and the sulfur content of the two iron concentrates are not overrun.
one. The nature of the ore
The results of multi-element analysis of ore chemistry and phase analysis of iron are shown in Table 1 and Table 2. It can be seen from Table 1 and Table 2 that the iron in the raw ore mainly exists in the form of magnetite and hematite (mostly hematite), and the others are a few iron carbonate and pyrite.
According to Table 1, the content of harmful elements phosphorus and arsenic in the raw ore is not high, both lower than 0.10%, but the sulfur is 0.36% high; according to the data in Table 2, the iron grade of the raw ore iron sulfide is very low at 0.045%, so the sulfur in the raw ore is not Derived from iron sulfide. The results of spectrum analysis of the raw ore indicate that the content of the raw ore is as high as 0.40%; therefore, most of the sulfur in the raw ore may come from barite (BaSO4) in the gangue deposit. Obviously, this kind of sulfur can be removed by physical beneficiation methods.
two. Experimental discussion and results
1. Raw ore grinding fineness experiment The raw ore is crushed to less than 2mm, the magnetic induction intensity of the magnetic separator is 0.15T, and the grinding fineness experiment is carried out. The results are shown in Figure 1 below.
It can be seen from Figure 1 that with the improvement of the grinding fineness, the iron grade crucible of the weak magnetic separation iron concentrate increases, and the iron recovery rate decreases; this is because the finer the raw ore grinding particle size, the more abundant the iron ore deposit is dissociated. Taking into account the feasibility of production practice, the grinding fineness is -0.074mm accounting for 90%, and the iron grade corresponding to the weak magnetite concentrate reaches 65.71%.
2. The grinding fineness of the raw ore weak magnetic separation experiment is -0.074mm, which accounts for 90%. The target of the iron concentrate changes with the magnetic induction intensity of the weak magnetic separation as shown in Figure 2. It can be seen that with the improvement of magnetic induction, the grade of iron ore concentrate decreases and the yield of iron ore concentrate increases. The main consideration is the iron grade target of the iron concentrate, and the magnetic induction intensity of the raw ore weak magnetic separation should be 0.15T.
3. The strong magnetic separation experiment of raw ore weak magnetic separation tailings is based on the results of iron phase analysis in Table 2. The iron dispersion rate of hematite in the raw ore accounts for 75.65% of the total iron; therefore, it is useful for separation of this type of iron ore deposits. It is the key factor to complete the useful separation of raw ore. For this type of iron ore deposit, the SLon-100 periodic pulsating high gradient permanent magnet cylinder magnetic separator is used, with a fixed pulsating stroke of 6mm and a stroke rate of 200r/min, selecting a 2 mm rod magnetic medium, and changing the magnetic induction intensity of the scene to achieve high pulsation. Gradient magnetic separation experiment, 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 drops, exceeding 0.8T, the iron grade drops significantly, and the iron recovery rate tends to stabilize; it is obvious that the magnetic induction intensity of the high-gradient magnetic separation of the raw ore should be 0.8 T. At this moment, the iron grade of the iron concentrate obtained is 49.87%, and the iron recovery rate is 60.90%. Therefore, after the strong magnetic magnetite is removed from the raw ore through the weak magnetic separation, only about 50% of the iron grade iron ore can be obtained by the gradient magnetic separation; the microscope observation of the iron ore shows that the iron grade is not high The primary reason for this is because there are many conjoined organisms. At the same time, this experimental result shows that the magnetite and hematite in the raw ore have different monomer dissociation degrees.
4. High-gradient strong magnetic coarse concentrate fine grinding experiment In order to obtain higher iron grade hematite concentrate, the coarse iron concentrate (fineness of -0.074mm accounting for 91.37%) of the previous high-gradient magnetic separation is carried out. The results of selected experiments and discussions are shown in Figure 4 below.
The operating conditions of this experiment select a pulsating stroke of 6mm, a pulsating stroke of 200r/min, a 2mm rod medium and a magnetic induction intensity of 0.8t.
As shown in Figure 4, as the grinding fineness improves, the ups and downs of the iron concentrate grade and iron recovery rate increase significantly, while the iron recovery rate decreases significantly. Therefore, the fine grinding particle size of coarse concentrate should be controlled at -0.074mm, accounting for about 97%. At this moment, the iron grade of the iron concentrate has increased from 49.87% to 55.86%, and the iron recovery rate is 39.95%. For the iron concentrate selected by iron, microscopic investigation found that the iron ore deposit has completely completed the monomer dissociation.
Therefore, fine grinding and beneficiation of the coarse concentrate obtained by high gradient magnetic separation can significantly improve the target of iron concentrate. In order to further improve the beneficiation goal of high gradient magnetic separation and explore the best operating conditions, the condition optimization experiment was carried out for the coarse and fine ore fine grinding and beneficiation operation. The results are shown in Table 3 below.
From the results in 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; but the operating recovery rate of the 2mm rod media is higher than the 3 mm rod media, although the latter The grade of the iron ore concentrate is slightly higher. The operating conditions of the selected operation should select the magnetic induction intensity 0.8T and 2mm rod medium.
5. High gradient and strong magnetic concentrate tailings gravity separation experiment
From Table 3 above, it can be seen that the iron grades of tailings in high-gradient beneficiation operations are relatively high, and directly discarded as tailings will seriously affect the total iron recovery rate; therefore, in order to explore the possibility of further improving the total iron recovery rate, The iron tailings obtained from the best high-gradient beneficiation operating conditions were subjected to shaker sweeping experiments. The experimental results show that for the high-gradient beneficiation of iron tailings, the skill targets of 52.76% and 3.58% of the iron grade and iron yield of the iron concentrate can be obtained, which is more significant.
three. Introducing process flow and continuous selection experiment results
1. Process flow In order to verify the feasibility of the above experiments in production practice, the best operating parameters determined by the above conditions are selected to conduct continuous selection experiments on the raw ore. The experimental flow is shown in Figure 5. The experimental results are shown in Table 4. In the continuous selection experiment, 2mm rod medium was used for both the rough selection and the selection test of high-gradient magnetic separation.
It can be seen from Table 4 that the raw ore is processed through the process in Figure 5, and the iron grade and iron recovery rate are 64.73% and 16.51% respectively, and the iron grade and iron recovery rate are respectively 56.51% and 46.58%. Red limonite concentrate. The analysis results of the two iron concentrates show that after the raw ore is processed through the above process, the content of sulfur, phosphorus and arsenic in the iron concentrate is 0.18%, 0.1% and 0.006%, and the content of sulfur, phosphorus and arsenic in the hematite concentrate is different. 0.20%, 0.04%, and 0.006%, and the content of sulfur, phosphorus and arsenic in the first-grade iron concentrate is required to be lower than 0.6%, 0.05% and 0.05%, so the harmful elements of the iron concentrate are not overrun; this result On the one hand, it proves the correctness of the previous analysis, and on the other hand, it explains the practical feasibility of the process. This technological process provides a feasible way for the separation of the same type of iron ore.