1. Test materials and methods (1) Test materials The test steel slag sample was taken from Taigang Group Linyi Iron and Steel Co., Ltd. In the steel slag sample, the main mineral components are dicalcium silicate, tricalcium silicate, calcium oxide and vitreous. According to the research of process mineralogy, the particle size distribution of metallic iron in steel slag is extremely uneven. The crystal size of magnetite, red and limonite is fine, and it is closely related to the intercalation of silicic calcium solid solution, which is difficult to dissociate. Metal minerals that can be directly recovered through beneficiation , mainly metal iron, magnetite, hematite and limonite. The steel slag was analyzed by multi-element chemical analysis, and its composition is shown in Table 1. Table 1 Results of chemical multi-element analysis element TFe FeO Si0 2 A1 2 0 3 CaO Mg0 S P K 2 0 Na 2 0 content/% 23.08 20.20 16.16 4.20 46.88 4.82 0.18 0.36 0.18 0.17 (2) Test methods Combined with the properties of steel slag, wet weak magnetic separation and wet strong magnetic separation comparison tests were carried out to obtain a suitable process route. Second, the test results and discussion (1) Wet weak magnetic separation test 1. Wet magnetic separation grinding fineness test The steel slag wet magnetic separation grinding fineness test is carried out in a weak magnetic field. The test has a fixed magnetic field strength of 0.16 T, and the grinding fineness is 60%, 70%, 80%, 90%, and 95% of the product of -200 mesh, respectively. The relationship between iron grade, recovery and grinding fineness can be obtained from the test data, as shown in Figure 1. It can be seen from Fig. 1 that the fineness of grinding has a great influence on the iron grade and recovery rate of iron concentrate. In the fineness of grinding -200 mesh 70%, the iron recovery rate is about 64%, the grade is about 59%; when the grinding fineness -200 mesh 80%, the iron recovery rate is increased to about 66%, but the grade is reduced. It is about 50%. Taking into account various factors, the grinding fineness is preferably -200 mesh and 75%. 2. Wet weak magnetic separation magnetic field strength test The steel slag wet magnetic separation magnetic field strength test was carried out under a fixed grinding fineness of -200 mesh and 92%, and the magnetic field strengths were 0.16 T, 0.145 T, 0.125 T, and 0.10 T, respectively. The relationship between iron grade, recovery and magnetic field strength can be obtained from the test data, as shown in Figure 2. It can be seen from Fig. 2 that as the magnetic field strength increases, the grade of iron concentrate decreases, but both are above 50%, and the recovery rate is significantly improved. At a magnetic field strength of 0.175 T, it reached 66.75%. Therefore, the weak magnetic field strength of 0.175T is preferred in this test. 3. Wet weak magnetic separation test results and analysis The steel slag wet weak magnetic separation verification test was carried out under the conditions of fixed grinding fineness - 200 mesh 75% and magnetic field strength 0.175T. The test results are shown in Table 2. Table 2 Wet weak magnetic separation verification test results product name Yield/% All iron grade /% Total iron recovery rate /% Iron concentrate 31.00 60.60 66.99 Tailings 69.00 13.42 33.01 Raw slag 100.00 28.98 100.00 It can be seen from Table 2 that the iron concentrate yield is 31.00%, the iron concentrate grade can reach 60.60%, and the total iron recovery rate is “66.99%. The test results are ideal. (2) Wet strong magnetic separation test 1. Wet strong magnetic selection magnetic field strength test In the test steel slag sample, there are weak magnetic mineral red and limonite. In order to further recover the iron in the red and limonite, the wet magnetic field strength test was carried out. The test raw material is the weak magnetic tailings of the wet weak magnetic separation magnetic field strength verification test. The relationship between iron grade, recovery and magnetic field strength can be obtained from the test data, as shown in Figure 3. It can be seen from Fig. 3 that as the magnetic field strength changes, the grade of iron concentrate does not change much, and the recovery rate increases. However, the grade of strong magnetic separation concentrate is only about 20%, and it is impossible to obtain qualified iron concentrate. 2, wet strong magnetic separation regrind test It can be seen from the results of the strength test of the strong magnetic separation of steel slag that the grade of strong magnetic separation concentrate is only about 20%. This may be because the crystal size of the red and limonite in the steel slag is small and does not reach the cause of monomer dissociation. Therefore, a strong magnetic separation regrind test was conducted, and the test magnetic field strength was 1.278T. The test results are shown in Table 3. Table 3 Results of fine magnetic separation test of weak magnetic separation tailings Grinding time / mm product name Yield/% grade/% Recovery rate/% TFe TFe 15 Iron concentrate Tailings Magnetic separation tailings 38.93 61.07 100.00 24.00 5.00 12.39 75.38 24.63 100.00 20 Iron concentrate Tailings Magnetic separation tailings 40.88 59.12 100.00 25.58 5.10 13.48 77.60 22.40 100.00 It can be seen from Table 3 that the weak magnetic separation tailings are reground and sorted under the same magnetic induction intensity. The iron concentrate grade can only reach 24% to 25%, which is far from the quality requirements of qualified iron concentrates. Moreover, the iron grade of the weak magnetic separation tailings is only 13% to 14%. Continue to improve the regrind, it is bound to increase the cost of grinding, economically not reasonable, so there is no need to continue to study in depth. (III) Analysis of quality inspection of iron concentrate In order to check the quality of mineral processing products, the quality analysis of iron concentrates was carried out, and the results of iron ore quality analysis are shown in Table 4. Table 4 Results of multiple chemical analysis of steel slag wet weak magnetic separation concentrate and tailings (%) Component TFe Si0 2 S P Cu Pb Zn Sn K 2 0 Na 2 0 As Iron concentrate 60.60 4.56 0.12 0.28 0.025 0.076 0.011 0.001 0.77 0.047 0.004 Tailings 13.42 37.70 0.10 0.24 0.016 0.071 0.99 0.001 0.65 0.041 0.001 From the analysis of the test results in Table 4, it can be seen that the wet weak magnetic separation process can select an iron concentrate having a grade of 60% or more from the steel slag. However, the excessive phosphorus-containing iron ore, phosphorus should be noted that in the smelting process. Third, the conclusion (1) The steel slag is wet-weak magnetic separation under the conditions of grinding fineness -200 mesh 75% and magnetic field strength 0.175T. The results show that the iron concentrate yield is 31.00%, the ore dressing ratio is 3.23, and the iron concentrate grade can be reached. 60.60%, the total iron recovery rate was 66.99%. (2) The wet weak magnetic separation process may select an iron concentrate having a grade of 60% or more from the steel slag. However, the iron concentrate contains excessive phosphorus. Toilent Tent,Military Toilent Tent,Army Crew Tent,Air Force Tents Bestway Industries (Group) Co., Limited , https://www.military-tents.com
Steel slag recycling technology
Steel slag is the waste residue generated during the steel making process, and the quantity is about 15% to 20% of the steel output. In recent years, with the rapid development of China's steel industry, steel slag emissions have increased. Slag contains a considerable amount of iron, iron metal containing an average of about 10%. Different types of steel slag can be used for different purposes. Steel slag with high TFe can be used as raw material for steel making, raw material for iron making, and as raw material for sintering. The remaining tailings are generally used for road construction, backfilling, and manufacturing of steel slag cement. Taigang Group Linyi Iron and Steel Co., Ltd. has an annual output of 300,000 tons of steel slag, and the content of iron in the converter waste is 17% to 28%. Except for some comprehensive utilization, these converter steel slags are all piled up in Dongwang slag yard. The comprehensive recovery of this part of iron in the converter slag has great long-term and practical significance for saving enterprise resources, reducing environmental pollution and increasing the economic benefits of enterprises. To this end, this test uses Lingang steel slag as raw material to carry out research on the process of recovering iron.