Iron ore resources in China has proven, the weak magnetic iron ore accounted for about 65% of the total iron ore reserves, which Anshan poor hematite accounted for more than half of the weakly magnetic mines. With the development of the steel industry, the rich ore is becoming more and more exhausted, and the proportion of poor ore is increasing year by year. Therefore, the development and utilization of this type of deposit is of great significance to the development of China's steel industry. The ore grade of the iron oxide ore studied in this paper is only 28.34%. Through the exploratory experiment on the whole magnetic separation process and the magnetic separation-stage grinding-reverse flotation process, the ideal selection index is finally obtained. First, the nature of the ore The type of the deposit is the Anshan-type sedimentary metamorphic iron deposit, and the ore type is mainly quartz -type mirror iron ore and magnetite. Metal ore minerals are mainly hematite, magnetite, hematite, wherein TFe / FeO ratio of 6.23, belonging to lean deeper degree of oxidation of iron ore. The gangue minerals are mainly quartz, which are mainly striped and banded, with a relatively uniform distribution, and only a small amount of mica amphibole minerals are partially mixed. The multi-element and iron phase analysis of ore is shown in Tables 1 and 2. Second, the full magnetic separation process test (1) Grinding particle size test The ore was ground to -200 mesh to 80%, 85%, 90%, and then weak magnetic separation, weak magnetic tailings strong magnetic separation test, weak magnetic field strength of 0.2T, strong magnetic separation test using Slon-100 The periodic pulsation high gradient magnetic separator has a background field strength of 0.5T. The test results are shown in Table 3. It can be seen from Table 3 that when the grinding particle size is -200 mesh 80% to 90%, the grade of the strong magnetic concentrate is 49.67% to 54.28%. If the concentrate and the weak magnetic concentrate are used together as a product, Affect the final grade of the product. If the grinding fineness is further increased, not only will the grinding cost be greatly increased, but also the over-grinding of the magnetite will be caused, and the final recovery rate of the product will not be guaranteed. Considering comprehensively, it is determined that the grinding particle size is -200 mesh 85%. (2) Strong magnetic tailings sweep test According to past experience, when the grinding grain size is controlled at -200 mesh, which accounts for about 85%, it is necessary to perform a sweep of the strong magnetic tailings to improve the comprehensive recovery rate. To this end, a strong magnetic tailings sweep test was conducted, and the results are shown in Table 4. In Table 4, the strong magnetic concentrate refers to a mixed ore sample selected by strong magnetic rough selection and strong magnetic sweep. (3) Strong magnetic concentrate selection and re-grinding and re-election test The strong magnetic concentrates with a grinding particle size of -200 mesh and about 85% (see Table 4) were separately selected and reground and re-selected. The test results are shown in Tables 5 and 6. Note: The strong magnetic concentrate is reground to a -200 mesh content of 95%. It can be seen from Table 5 and Table 6 that when the strong magnetic concentrate is re-elected or re-grinded, the concentrate grade is improved, but the “running tail†is serious, the tailing grade is high, and the metal loss is large, indicating The full magnetic separation process has certain limitations on the selection of the mine. Third, strong magnetic concentrate re-grinding - reverse flotation test (1) Regrind particle size test Referring to the domestic experience of processing "Anshan-type" lean red iron ore, the re-grinding operation of the strong magnetic concentrate is carried out. The test procedure is shown in Figure 1. The pharmaceutical system is: MH850g/t, NaOH1250g/t, corn starch 1000g / t, CaO500g / t, pulp temperature 30 ° C. The test results are shown in Table 7. From the regrind particle size test, as the fineness of grinding increases, the grade of flotation concentrate also increases, but the recovery rate is not guaranteed; at the same time, the increase of grinding fineness will increase the cost of ore dressing . Taking all these factors into consideration, it is more reasonable to use -200 mesh to account for 95% of the grinding size. (2) Reverse flotation closed circuit test Under the condition of regrind particle size of -200 mesh and 95%, the reverse magnetic flotation closed-circuit test was carried out on the strong magnetic concentrate. The flow is shown in Figure 2, and the test results are shown in Table 8. Fourth, the comprehensive process test Considering the selection effect of the full magnetic separation and the strong magnetic concentrate re-grinding-reverse flotation process, it is determined that the low-grade weak magnetic iron oxide ore is selected by the weak magnetic-strong magnetic-stage grinding-reverse flotation combined process. No, the quality process is shown in Figure 3. V. Conclusion (1) The iron ore mine with a grade of 28.34%, through the weak magnetic-strong magnetic separation operation, can only obtain iron concentrate with a grade of 51.82%~58. 00%, the recovery rate is 60.15%~73. 70%; After the product is passed through strong magnetic or re-grinding-strong magnetic separation operation, the grade of concentrate is not increased much, and the product recovery rate is less than 60%, indicating that the whole magnetic separation process is not ideal for the selection of the mine. (2) Using the "strong magnetic-re-grinding-reverse flotation" process for the weak magnetic tailings, not only increased the selected grade of reverse flotation by 28%, but also abandoned about 85% of the tailings, reducing the regrind. The processing volume of the operation greatly reduces the grinding cost. The effectiveness of the SLon vertical ring pulsating high-gradient magnetic separator for pre-magnetic tailing treatment before de-floating of lean magnetic iron oxide ore was once again verified. (3) In recent years, anti-flotation agents have emerged with new varieties, and the specificity of selection has become stronger. In this paper, the selection and dosage of anti-flotation agents are based on the experience of predecessors. If further research is carried out in these two aspects, the ore dressing indicators are expected to be further improved.
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