Study on Beneficiation Process of a Molybdenum, Zinc and Iron Complex Polymetallic Ore

First, the nature of the ore

The relative content of each mineral in the ore is shown in Table 1. The mineral composition of the ore is complex, and elements such as molybdenum , zinc , iron , copper , lead and sulfur are mainly present as independent minerals. The independent mineral of molybdenum is molybdenite; the independent mineral of zinc is sphalerite; the iron mineral is mainly magnetite, and occasionally a small amount of hematite and limonite are visible; the independent mineral of sulfur is mainly pyrite. , there are small amounts of pyrrhotite; other metals as well as trace minerals chalcopyrite, chalcocite, covellite and chalcocite blue copper minerals and other trace amounts of galena like. Gangue minerals are serpentine, talc, quartz, feldspar, calcite, dolomite, followed sericite, clay minerals, muscovite, biotite, as well as other mineral diopside, rutile and the like.

Table 1 Mineral composition table of ore

The inter-mineral inclusion relationship in the ore is more complicated. The molybdenum ore is closely related to the gangue mineral inlay, and is mainly distributed into the gangue minerals in the form of fine granules, followed by the irregular aggregates and plate-like local enrichment in the gangue minerals. Sphalerite is mainly embedded in gangue minerals in an irregular manner; sphalerite is closely related to chalcopyrite, pyrite and magnetite, and chalcopyrite is often found in the form of droplets embedded in sphalerite. The solid solution separation structure is formed, and the pyrite is sometimes closely symbiotic with it. Sometimes the sphalerite is filled with cementite magnetite along the magnetite gap. Magnetite is mainly embedded in gangue minerals, sometimes distributed in gangue minerals by star-shaped or fine veins; magnetite and sphalerite, pyrite, pyrrhotite Closer, sometimes closely associated with each other, sphalerite, pyrite, pyrrhotite often fills magnetite along magnetite fractures or voids; magnetite is often seen in the form of inclusions in pyrite in.

The molybdenum, sphalerite and magnetite have finer grain sizes and are not uniform. The embedding grain size of the molybdenum ore is generally 0.015 mm to 0.147 mm; the inlaid grain size of the sphalerite is generally 0.017 mm to 0.117 mm; and the inlaid particle size of the magnetite is generally 0.020 mm to 0.295 mm.

The main chemical composition analysis results of representative ore samples are shown in Table 2. The results of chemical phase analysis of molybdenum, zinc and iron are shown in Table 3.

Table 2 Analysis results of main chemical components of ore

Table 3 Analysis results of molybdenum, zinc and iron phases (%)

Second, the formulation of the beneficiation process

Process mineralogical studies have shown that in addition to the main metal minerals such as molybdenite, sphalerite and magnetite, the ore also contains more pyrite and pyrite and a large number of serpentine and Talc (accounting for 32.7% of the original ore) and other gangue minerals, because some of the minerals in serpentine and talc are very buoyant, it seriously interferes with the flotation of molybdenum ore, affecting the grade of molybdenum concentrate, so this part of serpentine Stone and talc minerals must be selected preferentially; for pyrrhotite, due to its strong magnetism, the unselected pyrrhotite will be magnetically selected into the iron concentrate together with the magnetite, so that the iron concentrate contains sulfur High and reduce the grade of concentrate, so pyrite should be selected as much as possible before iron selection.

According to the mineral processing characteristics of each mineral, the principle of beneficiation principle to be adopted: firstly flotation of talc and serpentine with good buoyancy; re-selection of molybdenum; then selection of zinc and sulfur; magnetic separation of flotation tailings to recover magnetite .

(1) Reverse flotation talc test

Due to its special structure, the talc has a strong oleophilic hydrophobicity and exhibits excellent floatability in the pulp, and its floatability is even better than that of molybdenite. Since talc and some friable gangue minerals are difficult to distinguish, they are uniformly classified into talc for convenience (the same below). In order to ensure the grade of molybdenum concentrate, it is necessary to first float the talc-like gangue minerals with excellent buoyancy to improve the grade of molybdenum concentrate.

Under the condition that the grinding fineness is -0.074mm and the grain size is 70%, the talc flotation test is carried out by using various chemicals, and the test results are shown in Fig. 1. The principle of flotation talc is to select talc with low molybdenum content, low molybdenum loss rate and moderate yield. From the test results, the talc containing molybdenum and molybdenum loss rate were lower with FT agent. When the amount of FT agent was 16g/t, the talc contained 0.46% molybdenum and the molybdenum loss rate was 2.65%. Determine the talc flotation using FT agent, the dosage is 16g / t.

Figure 1 Results of different pharmaceutical flotation talc test (agent dosage 16g/t)

(2) Flotation molybdenum

After the talc floats out, an experimental study on the recovery of molybdenum is carried out. Since the floatability of molybdenite is better than that of sphalerite, pyrite, pyrrhotite and the like in the ore, molybdenum preferential flotation is adopted.

1. Molybdenum rough selection collector dosage test

Under the condition that the grinding fineness is -0.074mm and the grain size is 70%, the talc is firstly floated with FT16g/t, then 2000g/t of water glass is used as gangue inhibitor, KB is used as collector, BK-205 is used. The foaming agent was subjected to a molybdenum test of two coarse and two sweeps. The test results are shown in Figure 2. From the test results, under the condition of fixed amount of foaming agent, with the increase of the amount of KB in the collector, the recovery rate first increases and then decreases, while the grade decreases first and then increases slowly, which indicates that the amount of collector and foaming agent exists. A reasonable ratio, through the test found that the ratio of collector to foaming agent is about 2:1, the test results are relatively good. In order to continue to increase the molybdenum recovery rate, the amount of collector and foaming agent was adjusted synchronously according to this ratio. Under the conditions of KB collector and BK-205 foaming agent dosages of 100g/t and 50g/t, respectively, molybdenum coarse The concentrate recovery rate increased from 70.32% to 77.58%, and the effect was obvious.

Figure 2: Test results for the amount of molybdenum collector KB

2, molybdenum rough selection of water glass dosage test

Water glass is used as an inhibitor for the gangue mineral composition and flotation characteristics of the ore. The test results are shown in Figure 3. From the test results, with the increase of the amount of water glass, the recovery rate of molybdenum coarse concentrate gradually increased from 62.10% to 81.01%, and the recovery rate of water glass increased to 8000g/t. Therefore, the amount of molybdenum crude water glass was determined to be 8000 g/t.

Figure 3 test results of molybdenum water glass

3. Grinding fineness test

The grinding fineness test was carried out under the conditions of determining the amount of collector and foaming agent, and the test results are shown in Fig. 4. From the test results, the molybdenum recovery rate of molybdenum concentrate increased from 75.33% to 83.19% under the condition that the grinding fineness increased from 60% to 85% of -0.074mm. It can be seen that fine grinding is beneficial to the recovery of molybdenum, which is consistent with the results of process mineralogical research. However, considering the small scale of production on site and management, the ore is still using a section of grinding, trying to improve the grinding fineness of a section of grinding. Therefore, the fineness of grinding is determined to be -0.074mm, which is 70%.

Figure 4 Grinding fineness test results

4. Re-grinding test of molybdenum coarse concentrate

Due to the fine grain size of the molybdenite deposit, in order to obtain a qualified molybdenum concentrate, the molybdenum coarse concentrate must be re-grinded. The results of the re-grinding test are shown in Figure 5. It can be seen that the grade of molybdenum concentrate increases with the increase of regrind fineness. In order to ensure that the grade of molybdenum concentrate is above 45%, the regrind is determined to be -0.038mm and the fraction is 95%.

Figure 5 Results of regrind test of molybdenum coarse concentrate

(III) Experimental study on zinc and sulfur selection

According to the amount of zinc and sulfur minerals in the ore and its floatable characteristics, at the natural pH of the ore, the molybdenum tailings are activated by copper sulfate, and the BM collector is used for the mixed flotation of zinc and sulfur.

1, copper sulfate dosage test

The test results of copper sulfate dosage are shown in Fig. 6. From the test results, when the amount of copper sulfate is too small, the zinc mineral cannot be completely activated; when the amount is too large, the excess copper sulfate will consume the collector, so the amount of zinc-selected copper sulfate selected is determined to be 250 g/t.

Figure 6 Test results of zinc sulfate

2, collector BM dosage test

Under the condition of determining the amount of copper sulfate, the collector BM dosage test was carried out, and the test results are shown in Fig. 7. It can be seen that the amount of the collector BM is preferably 70 g/t.

Figure 7 Zn dosage collector test results

3, zinc and sulfur separation lime dosage test

The test results of the separation of lime in zinc-sulfur mixed concentrate are shown in Fig. 8. From the test results, as the amount of lime increases, the grade of zinc concentrate rises. When the amount of lime reaches 2kg/t (pH=12.2), the grade of zinc concentrate is above 51%, so it is determined that zinc and sulfur are separated and coarsely selected. The amount of lime used is 2 kg/t.

Figure 8 Zinc-sulfur separation lime dosage test results

(4) Research on iron selection test

After the ore is selected by talc, molybdenum, zinc and sulfur, the tailings are used for the recovery of magnetite. The recovered magnetite is weakly magnetically selected. The flotation tailings are subjected to magnetic separation test under the condition of magnetic field strength of 0.12T. The grade of rough iron ore concentrate can only reach 45.38%, indicating that the magnetite has a fine grain size and is far below this fineness. Achieving full dissociation requires re-grinding of iron concentrates.

Selective tests for different regrinds of iron concentrates are shown in Figure 9. From the test results, the iron concentrate grade increased from 61.85% to 68.10% as the regrind fineness increased from 65% to 95% of the -0.038mm fraction; while the coarse concentrate was no longer ground, it was selected. The iron concentrate grade is only 55.89%. In order to ensure that the iron concentrate grade is above 65%, the proposed regrind fineness is determined to be -0.038mm and the grain size is 90%.

Fig. 9 Results of regrind test of iron coarse concentrate

(5) Closed circuit test

The closed-circuit process test was carried out on the basis of the open circuit test. The test results are shown in Table 4.

Table 4 Closed-circuit test indicators

Third, the conclusion

1. The useful mineral inlay in this ore is fine and uneven, and the easy-to-float gangue containing a large amount of talc is the main reason for the difficulty in selecting ore. According to the nature of the ore, fine grinding is necessary to obtain a reasonable beneficiation index. However, considering the uneven grain size of molybdenite, sphalerite and magnetite, the physical properties of minerals are quite different, so the stage grinding is reasonable. In addition, the reverse flotation of crater and other gangue minerals is very important for the selection of molybdenum concentrate.

2. The recommended beneficiation process is: using selective chemical anti-flotation talc and other easy-floating gangue minerals; then selecting molybdenum, molybdenum coarse concentrate and grinding 8 times to select molybdenum concentrate; then zinc and sulfur mixed Selected, mixed concentrate to separate zinc concentrate and sulfur concentrate; flotation tailings weak magnetic separation of iron, iron coarse concentrate re-grinding and then selected iron concentrate.

3, using this process, closed-circuit test obtained a molybdenum grade 45.54%, molybdenum recovery rate of 82.29% of molybdenum concentrate and zinc grade 48.07%, zinc recovery rate of 84.14% zinc concentrate, and iron grade 65.20%, on the original ore total iron The iron concentrate with a recovery rate of 53.46% (81.30% recovery rate of ore magnetite) also obtained a sulfur concentrate with a yield of 4.23%, a sulfur grade of 38.75% and a recovery of 60.42%, making molybdenum and zinc. Iron and sulfur have been comprehensively recovered.

references:

[1] Zhu Yushuang, Zhu Jianguang. The chemical principle of flotation reagents [M]. Central South University of Technology Press, 1987.

[2] Lin Chunyuan, Cheng Xiuyu. Beneficiation and deep processing of molybdenum ore [M]. Beijing: Metallurgical Industry Press, 1997.

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