Most of the iron ores in Xinjiang, Anhui, Hubei, Jiangsu and other places in my country contain pyrrhotite to varying degrees; in addition, some of the iron ores imported into my country from abroad also contain high pyrrhotite content. In order to make full use of this iron ore resource, desulfurization treatment must be carried out. However, due to the strong magnetism and poor floatability of pyrrhotite, and the large differences in the properties of pyrrhotite at different mineral sites, there are currently no mature processes and chemicals in China that can well combine it with magnetite. separation. After long-term research, Ma’anshan Mining Research Institute has developed a new activator MHH-1. After testing two domestic and foreign magnetites with high pyrrhotite content (sulfur content is 10.07% and 2.51% respectively) , achieved good desulfurization results, and the sulfur content in the final iron concentrate was reduced to less than 0.3%, meeting the quality requirements of the subsequent process for the iron concentrate.
1. Desulfurization test of an imported high-sulfur iron ore
(1) Ore properties
An imported high-sulfur iron ore has a total iron grade of 60.97% and a sulfur content of 2.51%. The sulfide ores are mainly pyrrhotite and pyrite, and the pyrrhotite content is relatively high. To utilize this imported mineral resource, it is necessary to conduct research on the desulfurization process. The multi-element analysis results and iron phase analysis results of the ore are shown in Table 1 and Table 2 respectively.
Table 1 Multi-element analysis results of an imported ore raw ore %
(2) Reverse flotation desulfurization test
1. Grinding fineness test
Crush the raw ore to 2~0mm, grind it to different fineness, and conduct a coarse and fine reverse flotation desulfurization test. The pharmaceutical system is: rough selection plus H2SO4600g/t, MHH-1 200g/t, dixanthate 240g/t, diesel 26 g/t, 2# oil 54 g/t, and one selected plus dixanthate 120 g/t , diesel 13 g/t, 2# oil 27 g/t, two selected dixanthate 80 g/t, diesel 8 g/t, 2# oil 17 g/t. The test results are listed in Table 3.
The test results show that as the grinding fineness increases, the sulfur content in the iron concentrate gradually decreases. When the grinding fineness reaches -0.076mm and accounts for 75%, the sulfur content in the concentrate has dropped to 0.29%, reaching meets the requirement of less than 0.3%. However, considering the requirements for metal spinning lamp iron photography
lampshade concentrate fineness in pellet processing and possible fluctuations in actual production, the grinding fineness was selected to be -0.076mm, accounting for 85%.
2. Rough selection condition test
(1) Sulfuric acid dosage test
Grind the raw ore to -0.076mm and account for 85% of the raw ore to conduct a coarse sulfuric acid dosage test. The fixed conditions are: MHH-1200g/t, butyraldehyde 240 g/t, diesel 26 g/t, and 2# oil 54 g/t. The test results are listed in Table 4.
The test results show that as the amount of sulfuric acid increases, the sulfur content in the iron concentrate gradually decreases, but the change trend is slow. Based on the test results, the sulfuric acid dosage was selected to be 600g/t.
(2) Activator test
Activator is a key agent that affects the desulfurization effect. In particular, pyrrhotite has poor floatability, so it is particularly important to use a suitable activator to activate it. To this end, the activator was first selected, that is, three schemes were compared: no activator, using CuSO4 as the activator, and using MHH-1 developed by Maanshan Mining Research Institute as the activator. The test adopts the same process structure and pharmaceutical system as the grinding fineness test. The test results are listed in Table 5.
The test results show that without adding an activator or using CuSO4 as the activator, the sulfur content in the final iron concentrate is difficult to reduce to less than 0.3%. However, using MHH-1 activator to activate pyrrhotite has a more obvious reverse flotation effect. , the sulfur content in the final iron concentrate has been reduced to 0.29%, therefore, MHH-1 was selected as the activator.
After selecting MMH-1 as the activator, a rough dosage test was conducted. In the test, the dosage of H2SO4, butyraldehyde, diesel, and 2# oil were fixed at 600, 240, 26, and 54g/t. The test results are listed in Table 6.
The results show that when the dosage of MHH-1 is above 200g/t, the desulfurization effect remains basically unchanged, so the dosage of MHH-1 is selected to be 200g/t.
(3) Collector test
First, a rough selection comparative test of B-xanthate and D-xanthate as collectors was conducted. The fixed conditions of the test are: H2SO4 600g/t, MHH-1 200g/t, diesel 26g/t, 2# oil 54g/t. The test results are shown in Table 7. It can be seen from the test results that, under the premise that other conditions remain unchanged, using ethyl xanthate as the collector, the sulfur content in the iron concentrate after rough separation is 1.65%, while using ethyl xanthate as the collector, After rough separation, the sulfur in the iron concentrate has been reduced to 1.00%. Therefore, dixanthate was chosen as the collector.
After it was determined to use dihuang as a collector, a rough selection and dosage test was carried out. The test fixed conditions are the same as above.
It can be seen that as the dosage of dichuang increases, the sulfur content in the iron concentrate gradually decreases. When the dosage of dichuang reaches 250g/t, and the dosage is increased, the decreasing trend of sulfur content in the iron concentrate slows down. , therefore, the medicinal dosage of rough-selected butyricum is 250g/t.
According to the production practice of similar ores and the research results on reverse flotation of pyrrhotite, diesel can assist and strengthen the collector of pyrrhotite. Therefore, a crude diesel dosage test was carried out. The fixed conditions of the test are: H2SO4 600g/t, MHH-1 200g/t, butyraldehyde 250g/t, 2# oil 54g/t. The test results are listed in Table 9. It can be seen from the test results that after adding diesel, the desulfurization effect is significantly improved, and the rough selection dosage is selected to be 26g/t.
(4) 2# oil dosage test
Using 2# oil as the foaming agent, a rough selection test was conducted. The fixed conditions of the test are: H2SO4 600g/t, MHH-1200g/t, butyraldehyde 250 g/t, and diesel 26 g/t. The test results are listed in Table 10. Based on the test results, the rough selection 2# oil dosage is selected to be 54 g/t.
3. Reverse flotation test
On the basis of the rough separation condition test, after a series of exploratory tests such as the number of selections and the selection agent system, a reverse flotation desulfurization was carried out based on the grinding fineness of -0.076mm accounting for 85% and the agent system listed in Table 11. Crude and fine process tests, the results are shown in Table 12.
It can be seen that after the imported iron ore is desulfurized by reverse flotation using MHH-1 new activator, an iron concentrate product with a sulfur content of 0.25% can be obtained, but its full iron grade can still be improved, so it is planned to be deslimed to improve iron grade.
(3) Reverse flotation iron ore desliming assembly and testing
The reverse flotation iron concentrate with a full iron grade of 64.35% was used to conduct a desliming test using a vertical magnetic gravity separator to further improve the iron grade.
It can be seen from the test results that after desliming the reverse flotation concentrate, the iron grade can be increased from 64.35% to 66.08%, and the operating recovery rate is 97.89%.
(4) Reverse flotation-desliming whole process test
Reverse flotation-desliming test process for an imported iron ore
It can be seen that the imported ore is ground to -0.076mm and accounts for 85%. After the reverse flotation and desliming process, an iron concentrate with a yield of 80.05%, an iron grade of 66.08%, and a sulfur content of 0.24% can be obtained. At present, the research results have been successfully transformed into industrial production.
(1) Using the MHH-1 new activator developed by Maanshan Mining Research Institute, its desulfurization effect is significantly better than that of CuSO4 and other activators.
(2) MHH-1 activator has the advantages of low dosage and low cost. It can effectively solve the problem that many mines currently have high sulfur content in concentrates due to the presence of pyrrhotite in iron ore. Sulfur offers new pathways.