Beneficiation test of a red and limonite

With the high-quality iron ore resources and easy option of gradually reducing, especially the rapid development of China's iron and steel industry iron ore resources has highlighted the extremely tight, red, limonite and efficient beneficiation technology has gradually become the main direction of research in recent Significant progress has been made in the year. Due to the rising price of imported iron ore in recent years, the iron ore supply of iron and steel enterprises is tight, and the production cost has risen sharply, which has seriously restricted the sustainable development of steel production enterprises. In order to effectively solve the problem of iron ore resources, major steel companies are seeking new iron ore resources. Red and limonite resources, which were previously difficult to select and have low utilization rates, have become the focus of attention. At present, red and limonite are mainly treated by gravity ore dressing , magnetization roasting-magnetic separation, and magnetic separation-flotation. For the fine-grained weak magnetic red and limonite, foreign countries have selected the flocculation-magnetic separation process to obtain higher sorting efficiency and sorting index. The inlaid cloth of a red and limonite in Shanxi is very fine, and it is cemented together with clay minerals. It is difficult to dissociate the monomer. The process of single-magnetic separation and flotation can not reach the ideal index. The use of mirror iron ore blending is conducive to strengthening grinding and scrubbing, and has a significant effect. It can obtain good technical indexes of iron grade 60.15% and recovery rate 52.28%.

First, the nature of the ore

The ore sample used in the test was provided by a company in Shanxi. The multi-element chemical analysis of the sample was carried out. The results are shown in Table 1. The iron phase analysis results in the ore are shown in Table 2.

Table 1 Results of multi-element chemical analysis of ore

Table 2 Results of ore phase analysis

As can be seen from Table 1, the main components in the ore are Fe ₂ O ₃ , A1 ₂ O ₃ , SiO ₂ , and the TFe content is 41.80%. The content of Al and Si in the ore is high, especially A1 ₂ O ₃ 22.60%. A small amount of phosphorus (P ₂ O ₅ ) and SrO ₂ , trace amounts of K ₂ O, CaO, MgO, TiO ₂ , MnO and S. The substances to be removed by beneficiation are Al ₂ O ₃ , SiO ₂ , P ₂ O ₅ .

It can be seen from Table 2 that the ore sample does not contain ferromagnetic iron. The iron is mainly in the form of red and limonite, and its distribution rate accounts for 98.94%. The small amount exists in the form of pyrite, carbonate and silicate. . Theoretical analysis shows that with strong magnetic separation and high gradient magnetic separation, the recovery should be above 80%. In fact, due to the too small particle size of the red and limonite inlays, the symbiotic relationship with the gangue minerals is complicated, and the recovery rate in the test will be greatly affected.

Process ore mineralogy studies indicate that the main metallic minerals limonite and hematite; gangue minerals are mainly kaolinite, mica, Ling Ming ore, phosphate rock and so on. Iron minerals by size into two parts, most of iron minerals disseminated fine grain size, typically in a clever forest 6 m, as a cement-like hematite and bauxite or clay mineral aggregates cemented together, See Figure 1 (the bright particles in the photo are hematite). The dissociation of such ore monomers is difficult, and the iron mineral content is 30% to 35%, which is difficult to select by conventional single magnetic separation and flotation processes. The other part of the iron mineral inlay has a coarser grain size, generally in the range of 74 to 362 m. Iron minerals and clay minerals, bauxite contact edges are rugged, and some hematite contains gangue minerals below 10 m, see Figure 2. This part of the red and limonite is relatively easy to dissociate due to the large particles. The inclusion of iron minerals with fine grain size will affect the final concentrate grade and recovery rate.

Figure 1 Hematite in the form of a cementitious distribution

The bright particles in the photo are hematite.

Figure 2 Hematite with rugged edge contact with bauxite

The bright particles in the photo are hematite, and the particles are 0.486~0.1862mm;

The white arrow refers to the void, and the bauxite is 0.0528 to 0.092 mm (the mineral indicated by the black arrow)

Second, the formulation of the test plan

The results of process mineralogical studies show that most of the red and limonite inlays are finely grained and cemented with gangue minerals. Part of the hematite contains gangue minerals below 10 μm, and the interior of the clay minerals always contains fine-grained hematite. Grinding to -45 μm, iron minerals are difficult to completely dissociate. The ideal iron concentrate grade and recovery rate cannot be achieved by re-election, magnetic separation and flotation processes, and the grade of tailings is higher. Therefore, according to the characteristics of the original ore, it is proposed to use other ores to carry out ore blending, and then shake the bed to achieve the purpose of improving the iron grade and recovery rate.

Third, the selection scheme test

(1) Incorporation of limestone and feldspar test

The silicate limestone and feldspar with high hardness are used to blend the red and limonite, strengthen the selective grinding and scrubbing effect, and improve the concentrate grade. The ore is mixed with limestone and feldspar in a ratio of 7:1 and 6:1, respectively, and ball milled by XMB-70 three-roller four-cylinder grinding machine, ball milling for 6 min and 8 min respectively, grinding concentration of 60%. A shaker test of -0.097 mm (160 mesh) in the grinding product was carried out. Shaker conditions: lateral slope 0.5 °, flushing water 216 kg / h, stroke 16 mm, stroke 320 r / min. The test results are shown in Table 3.

Table 3 Results of rough selection of gray stone and feldspar shaker

It can be seen from Table 3 that the original ore is mixed with limestone and feldspar for the shake test. The iron concentrate grades are 56.70% and 55.14%, respectively, but the yield and recovery are extremely low, only 11.14%, 12.74% and 17.33%, 19.68%. And the yield and recovery rate of tailings is higher. The reason is that the symbiotic relationship between the iron minerals and the gangue minerals with fine grain size in the ore is complicated, and it cannot be recovered after being mixed with limestone and feldspar, and is lost in the tailings together with the gangue minerals.

In order to further improve the concentrate grade, a shaker concentrate blended with feldspar minerals is further subjected to a shaker sorting. Shaker conditions: rinse water 288kg / h, other conditions remain unchanged. The test results are shown in Table 4.

Table 4 Selected test results of the feldspar shaker

It can be seen from Table 4 that after two shaker sorting, the grade of the concentrate is 60.37%, the operation recovery rate and yield are 38.92%, 35.56%, and only 7.66% and 4.53% for the ore. not ideal. Obviously, it is not feasible to use the mixed fly ash and feldspar blending process for the mine.

(2) Incorporation into the specular iron ore test

The mineral composition of the mirror iron ore is relatively simple. When the ore is ground to -0.074mm, about 90% of the monomers are dissociated. The target mineral is specular iron ore (a variant with high degree of crystallization in hematite), and the general particle size is between 0.074 and 0.135 mm, which is an easy ore.

1, shaker test

The ore and the specular iron ore are mixed in a ratio of 5:2 for ore blending. The ore grade of the mirror iron ore is 44.60%, and the theoretical grade after ore blending is 42.60%. Grinding 8min, grinding fineness -0.097mm (160 mesh) accounted for 83.67%. The -0.15 mm product was subjected to a shaker test, and the shaker conditions were the same as 3.1. The test results are shown in Table 5.

Table 5 Test results of blending into the porphyrite shaker %

It can be seen from Table 5 that the blending of specularite in the ore is carried out for the shaker test, and a good technical index of 61.79% of the iron concentrate grade and a recovery rate of 32.68% can be obtained.

2. Conditional test

(1) Different ratios of ore ratio tests. The ore is combined with specular iron ore, the ratio is 3:1, 4:1, 5:1, 6:1, grinding concentration is 60%, grinding is 7min, grinding fineness is -0.097mm, accounting for 85.41 %, the product of -0.15mm was subjected to a shaker test, and the condition of the shaker was the same as 3.2.1. Under this condition, the product of the bedside concentrate was broadened. The test results are shown in Table 6.

Table 6 Shake test results of different ore blending ratios %

It can be seen from Table 6 that the higher the ratio of the specular iron ore, the higher the grade and recovery rate of the concentrate obtained. When the ratio is 3:1, the grade and recovery rate reached 59.86% and 32.73%.

(2) Different grinding fineness tests. According to the ratio of raw ore to specular iron ore 4:1, different grinding fineness tests were carried out, and the grinding concentration was 60%. The grinding fineness results of different grinding times are shown in Table 7.

Table 7 Relationship between grinding time and grinding fineness

It can be seen from Table 7 that as the grinding time increases, the grinding fineness also increases. However, the increase is slow after 7 minutes, and the longer the grinding time, the more likely the ore is crushed, which affects the beneficiation index.

The shake test was carried out in -0.15 mm of the grinding product, and the test results are shown in Table 8.

Table 8 Shake test results of different grinding fineness

It can be seen from Table 8 that as the fineness of the grinding increases, the grade of the concentrate gradually becomes higher, but the recovery rate gradually decreases. Considering comprehensively, the grinding fineness is selected to be -0.097mm 85.41%, and the concentrate grade and recovery rate are 57.58% and 34.26%.

It can be seen from the above test that when the ratio of the ore and the specular iron ore is 5:2, the obtained iron concentrate has a high grade and a large recovery rate. The reason is that the hardness of the mirror iron ore is better, it can better play the scrubbing effect, and the dissociation degree and recovery rate of the ore monomer are improved. Therefore, the ratio of the original ore to the specular iron ore is selected to be 5:2 for the flow test.

3. Process test

Grind the prepared ore to -0.097mm to 85.41%, first carry out the shaker rough selection condition test, the conditions are the same as 3.2.1, select the coarse concentrate obtained from the best condition of the shaker, and select the tailings to return to the rough selection. . The test procedure is shown in Figure 3, and the test results are shown in Table 9.

Figure 3 Shaker rough selection - selection process

Table 9 Shaker rough selection - selected test results

From the results of Table 9, it can be seen that the mixed ore is roughly selected by the shaker, and the coarsely selected concentrate is selected once by the shaker. The iron concentrate grade is 60.15%, the recovery rate is 52.28%, and the recovery rate is greatly improved compared with other schemes.

Fourth, the conclusion

Through the mineral technology research and ore-matching test on a red and limonite in Shanxi, the ore's inlaid grain size is very fine, and it is cemented and cemented together with clay minerals. After grinding to -45μm, the ore still cannot be single. Complete dissociation is extremely difficult to select ore. The process of using single magnetic separation and flotation can not achieve the desired index. The use of silicate limestone and feldspar ore to ore and limonite ore to enhance selective grinding and scrubbing, the ore dressing index is still not ideal, the concentrate grade and recovery rate are low, and also reduce the iron content of the ore. grade.

The use of specular iron ore blending is conducive to strengthening grinding and scrubbing, has a significant effect, and can obtain meaningful beneficiation indicators. When the ratio of mirror iron ore to red and limonite is 2:5, the fineness of grinding -0.097mm accounts for 85.41%. Once the shaker is coarsely selected and selected once, it can reach 60.15% of iron concentrate grade, and the recovery rate is 52.28%. The better indicators provide a technical basis for the development of the iron ore resources, and have reference and reference value for the development and utilization of other similar iron ore.

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