In recent years, increasing demand for iron ore, iron ore and high-grade ore richer or can not meet the market demand, poor and ultra-poor magnetite ore development and utilization of more and more attention. However, due to the low content of ferromagnetic iron minerals in super-poor magnetite, if the original ore is crushed and directly ground and then magnetically selected, the grinding cost will be greatly increased, resulting in high cost of the entire beneficiation , or even profitability. . Therefore, for the ultra-poor magnetite, a more optimized process should be adopted to reduce the cost of beneficiation. This paper takes the demineralization test of a super-poor magnetite in Xuanhua, Hebei Province as an example, and introduces the process flow of dry-selection waste-discharging, dry-selection concentrate coarse grinding magnetic separation appendix and coarse concentrate re-magnetization. The test results show that the use of this process is a more reasonable method of mineral processing for processing super-poor magnetite.
I. Analysis of ore phase of iron ore
From the results of the analysis of the ore iron phase (Table 1), the iron ore grade is very low, especially the iron content in the magnetic iron mineral is only 8.53%. If such iron ore is directly broken into the mill for grinding, a large amount of waste rock will be ground into the mill to be ground, which greatly increases the grinding cost, and even makes the total beneficiation cost higher than the concentrate sales, resulting in a loss. . Therefore, it is necessary to throw away the waste rock as much as possible before grinding. For this reason, the raw ore is first subjected to dry selection and throwing waste test.
Table 1 Results of ore phase analysis
Second, dry selection test
The ore is crushed to -8mm, and the φ1050×600 dry magnetic separator is used. The magnetic field strength is 3500οe, and the dry selection is performed. The dry selection results are shown in Table 2.
Table 2 Results of dry selection test
From the results of the dry selection test, after dry selection, more than 67% of the waste rock can be discarded. The content of magnetic iron in waste rock is only 1.77%, the total iron content of dry concentrate is increased from 13.67% to 26.35%, the content of magnetic iron is increased from 8.53% before dry selection to 21.87%, and the recovery rate of magnetic iron is over 85%. The effect of dry selection is very obvious. In this way, the ore can throw away 67% of the waste rock before grinding and the magnetic iron loss is small. The amount of minerals entering the mill is greatly reduced before the dry selection, which effectively reduces the grinding cost.
Third, dry selection concentrate rough grinding - magnetic separation test
Although more than 67% of the dry-selected tailings have been produced by dry magnetic separation after crushing, the dry concentrate concentrate is only 26.35%, and the magnetic iron grade is crushed to -2mm (which can be achieved by rough grinding at the production site). For wet magnetic separation, a magnetic-(GX) 167 drum magnetic separator was used, with a drum size of φ327×180 and a magnetic field strength of 1200 οe. The test results are shown in Table 3.
Table 3 Results of rough grinding and magnetic separation test of dry concentrate
From the test results, under the condition of coarse grinding -2mm, the coarse-grained tail is made by magnetic separation, the grade of magnetic separation concentrate is increased from 26.35% to 34.45%, and the operation recovery rate is 91.83%. The rate (sell rate) was 29.86%, and further produced a tailings close to one-third of the weight of the dry-selected concentrate, further reducing the amount of grinding of the fine grinding. The test results show that the effect of rough grinding magnetic separation is obvious.
Fourth, coarse grinding magnetic separation concentrate re-magnetization test
(1) Different grinding fineness magnetic separation tube test of coarsely ground magnetic separation concentrate
The XCS-73 type magnetic 50 mm magnetic tube is used. The magnetic field strength is set at 1200 οe, and the coarse grinding magnetic separation concentrate is used for different grinding fineness magnetic separation tube test. The test result is shown in Yuan 4.
Table 4 Test of different grinding fineness magnetic separation tube for coarse grinding magnetic separation concentrate
From the test results, as the grinding fineness increases, the concentrate grade continues to increase. When the grinding fineness is -200 mesh 49% or more, the concentrate grade can reach more than 65%.
(2) Magnetic separator test
Grinding fineness is set at -200 mesh and accounts for 50%. The magnetic- (GX) 167 drum magnetic separator is used, the drum size is φ327×180, and the magnetic field strength is 1200 οe. The test results are shown in Table 5. The results of the concentrate analysis are shown in Table 6.
It can be seen from the multi-element of concentrates that the phosphorus and sulfur content in the concentrate are not exceeded.
Table 5 Magnetic separator test results
Table 6 Results of multi-element analysis of concentrate
V. Calculation of acidity and alkalinity of concentrate
It is an alkaline iron concentrate.
6. Conclusion
For ultra-poor iron ore with recoverable iron minerals and magnetite-based, the process of dry-selection and waste-discharging, dry-selection concentrate coarse-grained magnetic separation of tails and coarse concentrate re-magnetization can be reduced. Grinding, greatly saving grinding costs. The test results show that the use of this process is a more reasonable method of mineral processing for processing super-poor magnetite.
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