Tailings are tailings produced by flotation recovery of nickel minerals. Chemical analysis shows that the total iron grade in the tailings is 10.07%, the magnetic iron grade is 2.95%, and the magnetic iron accounts for 29.29% of the total iron. The tail minerals are mainly recyclable. It is a magnetite with comprehensive recycling value. A beneficiation test for the comprehensive recovery of minerals in the nickel tailings.
First, the nature of the ore
The results of chemical multi-element analysis and iron phase analysis of nickel tailings samples are shown in Table 2 of Table 1. Nickel tailings magnetite accounts for 20.55%, pyrrhotite accounts for 6.85%, and pyrrhotite accounts for 6.85% of pyrite, which has a certain impact on the quality of iron ore products.
Second, the principle process
Due to the strong magnetic properties of the magnetite ore, there is a strong magnetic agglomeration between the magnetite and the magnetite. Therefore, the magnetite ore will enter the iron concentrate synchronously in the process of the second process, and it is difficult to separate by magnetic separation. Magnetite and pyrrhotite, but the pyrrhotite has a certain floatability after activation, so flotation is an effective way to reduce sulfur in iron concentrate. Since the main mineral of the tailings is magnetic ore dressing, the process of using the magnetic front and the floating is reasonable, and the iron concentrate after the magnetic separation is desulfurized by flotation, and a qualified magnet concentrate product is obtained.
Third, magnetic separation conditions experiment
1. Rough magnetic induction The strong magnetic induction intensity is the main factor affecting the selection of magnetic separation. Strong magnetic induction may cause some magnetic minerals to be lost without being selected. If the magnetic induction is too strong, it will cause the gangue minerals to be mixed in the magnetic products, thus affecting the concentrate grade. Since the test sample is nickel tailings and the particle size is fine, it is determined that the tailings are subjected to a magnetic separation to recover iron without grinding. The rising water flow of the magnetic separator is 360L/h. The experimental results are shown in Fig. 1. As the magnetic induction intensity increases to 120MmT, the iron grade and recovery index of the obtained iron concentrate are ideal, so the rough magnetic induction intensity is determined. It is 120ml.
2. Grinding fineness In order to further improve the grade of iron concentrate, the fineness test of the magnetic separation iron concentrate is carried out under the condition of the selected magnetic induction intensity of 60 mT. The experimental results are shown in Fig. 2.
It can be seen from Fig. 2 that with the increase of grinding fineness, the grade of iron concentrate is increasing. When the fineness of grinding is -38um or more than 80%, the iron grade and iron recovery rate remain basically the same. , to determine the grinding fineness of -38um accounted for 80%.
3. Selected magnetic induction intensity The selected magnetic induction strength test is carried out on the basis of grinding fineness - 38um 80%. The test results are shown in Fig. 3.
It can be seen from Fig. 3 that the iron concentrate grade slightly decreases with the increase of the magnetic induction intensity. When the magnetic induction intensity is greater than 60 mT, the iron recovery rate does not change much, so the selected magnetic induction intensity is determined to be 60 Mt.
4. Magnetic separation process The whole process of magnetic separation process is shown in the following figure. The test results are shown in Table 3.
It can be seen from Table 3 that the nickel tailings can obtain an iron concentrate with a total iron grade of 62.10% and a total iron recovery rate of 27.97% through a magnetic separation process, and the iron concentrate contains 7.85% of sulfur, which does not reach the iron concentrate grade. The requirements of the sulfur content index indicate that the magnetic pyrrhotite in the tailings has an enrichment effect in the magnetic selection and needs to be treated with sulfur reduction.
Fourth, iron concentrate flotation to reduce sulfur
1, determines the kind of the activator activator oxalic acid, sodium fluoride, sulfuric acid and copper sulfate on pyrrhotite, and combinations of a single species plus contrast, flotation results show that sulfuric acid and oxalic acid, compared to other agents, the resulting iron ore The sulfur reduction effect is better. Because the sulfuric acid price is relatively low, it is determined that sulfuric acid is used as an activator for sulfur reduction of iron concentrate.
2. The iron ore flotation and sulfur reduction process uses sulfuric acid as the activator, and the butyl xanthate is used as the collector to test the sulfur reduction of the iron concentrate and the comprehensive recovery of sulfur. The test procedure is shown in Figure 5. Raw ore (nickel tailings) is selected in g/t. The same test results are shown in Table 4. As the test results show, the test can obtain qualified iron concentrate and sulfur concentrate.
3. The amount of sulfuric acid used as a mineral processing agent has the dual effect of affecting both the test index and the beneficiation equipment. According to the test procedure, a rough selection and a sweeping sulfuric acid dosage test are carried out. The test results are shown in Table 5. It can be seen from Table 5 that the amount of sulfuric acid is preferably 450+220 g/t.
4. The amount of butyl xanthate is determined by the amount of sulfuric acid 450+220+110g/t, and the amount of the butyl yellow drug is roughly selected and twice selected for the iron concentrate. The test results are shown in Table 6. It can be seen from Table 6 that with the increase of the amount of butyl yellow, the sulfur content of iron concentrate gradually decreases. When the crude amount of butyl yellow drug is 70g/t, an iron concentrate containing 0.17% sulfur can be obtained. The test results are ideal.
V. Magnetic-floating full-process closed-circuit test
In the above condition test, the whole process closed circuit test was carried out. The test procedure is shown in Figure 6. The test results are shown in Table 7. From Table 7, we can see that the magnetic-floating full-circuit closed-circuit test can obtain 65.20% qualified iron concentrate with iron grade and 22.50% sulfur concentrate with sulfur.
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