Experimental study and practice of improving the beneficiation index of a molybdenum ore

Molybdenum is found quite late one metal element, it was refined in 1792 by the Swedish chemist from molybdenite. Metal molybdenum is widely used in the industry because of its high strength, high melting point, corrosion resistance, and abrasion resistance.

Due to the increased mining depth in a molybdenum mine, the ore properties have changed. The variety of minerals increases and the mineral inlay relationship is more complicated. Distribution of most metallic minerals pyrite, accounting for 5.86% of the total of mineral, followed molybdenite, accounting for 0.63%, less mineral content of other metals. Most non-metallic minerals quartz content, accounting for 40.19%, followed by sericite, feldspar, biotite. Some molybdenites have poor crystallinity and more fine-grained inlays, and -38 μm accounts for 23.35%. The gangue minerals are severely altered, and the muddy minerals are sericite, chlorite, kaolin , and fault mud, so the degree of muddy in the ore is higher. In addition, there are graphite harmful minerals in the ore. Due to the above characteristics of the ore, the on-site production process and conditions cannot be adapted to the ore properties. The molybdenum concentrate has a low molybdenum grade and recovery rate, which seriously affects the economic benefits of the enterprise. To this end, the experimenter conducted a mineral processing test on the basis of the ore mineral composition and various mineral characteristics. The molybdenum concentrate has a significant improvement in molybdenum grade and recovery rate, thus creating greater economic and social benefits for the enterprise. .

First, the nature of the ore

(1) Mineral composition and relative content of ore

Metal ore minerals are nine kinds, the largest distribution pyrite, molybdenite followed, other metals not high mineral content, wherein the manganese ore and tetrahedrite less uniform distribution of the graphite in the ore, local enrichment. Non-metallic minerals have the highest content of quartz, followed by sericite and feldspar, biotite, and other minerals. The mineral composition and content of ore are shown in Table 1.

Table 1 Mineral composition and relative content of ore

(2) Molybdenum ore impregnation granularity

The grain size of molybdenum ore in the ore is relatively uniform in each size, but the distribution of fine-grained grade (-38μm) is more than that. It should be uniformly embedded in fine particles. The statistical results of molybdenum ore dip-dyeing are shown in Table 2.

Table 2 Statistical results of molybdenum ore dip staining %

(III) Main mineral output characteristics

Pyrite: Pyrite is the most abundant in metal minerals and is widely distributed. Pyrite is mostly produced by self-formed crystals, semi-automorphic crystals and other granular forms and aggregates. Due to the early formation of pyrite, there are late chalcopyrite, sphalerite and galena filling intrusion in the grain fissures and intergranular spaces, and the latter is more than the former, so that the pyrite is mostly residual structure. At the same time, pyrite is also interspersed with molybdenum ore. In the ore, pyrite is mostly produced as a single particle and distributed in the gangue, forming a typical disseminated structure. The aggregate particles are coarse, forming a mass and Point structure, but not widely distributed.

Molybdenum ore: Molybdenum ore is a valuable mineral in the ore and is widely distributed. The molybdenum ore is mostly distributed in the crevices and holes of the gangue in the form of plates, slats, strips, short veins and flakes, and the grain boundary is relatively clear, some molybdenum ore is poorly crystallized, and the aggregate particles are not blurred. In the Qing Dynasty, a small part of molybdenum is distributed in star-like and muddy soils in altered sericite and chlorite, and the grain boundary is unclear. The latter two kinds of molybdenum ore have a great influence on the beneficiation. Generally speaking, the dissociation is difficult and it is difficult to sort. The molybdenum ore is closely related to the metal mineral pyrite in the ore and has a certain contact relationship. The molybdenite deposits along the crushing fissures of the pyrite and interprets the pyrite; in addition, it is filled with cement in the gap between the chalcopyrite particles, and the chalcopyrite is replaced by a metamorphic structure; in the molybdenum ore, pyrite and yellow are often included. Fine particles of copper ore.

Molybdenite is closely related to gangue minerals, especially to altered gangue minerals such as sericite and chlorite. Molybdenite is mostly distributed in sericite and chlorite, and is often smashed. The mica and chlorite surround, forming a reaction side and an outer shell, and have a ring-shaped, ring-shaped structure. Sometimes the molybdenum ore contains fine particles of gangue minerals. The above-mentioned output characteristics of molybdenite and gangue minerals have a great influence on the selection of molybdenite, and it is considered that the ore is difficult to distinguish.

Sericite: It is the most important muddy mineral in ore, and its content is second only to quartz. Sericite is mostly produced in small scales and is derived from feldspar alteration products. Sericite has low hardness and fine particles, so it is brittle and easy to mud.

Feldspar: The feldspar is produced in thick plate and irregular shape, and the feldspar is mostly etched into sericite, so the feldspar granules are unclear and the degree of alteration is high. Some feldspar particles are weathered into kaolin, and the latter are mostly distributed on the surface of feldspar. Feldspar and quartz are often produced.

(4) Multi-element analysis of raw ore chemistry

The results of multi-element analysis of ore chemistry are shown in Table 3.

Table 3 Multi-element analysis results of ore chemistry

(5) Analysis of original ore molybdenum phase

The results of analysis of the ore molybdenum phase are shown in Table 4.

Table 4 Analysis results of ore molybdenum phase

Second, the site overview and problem analysis

The process of the ore dressing plant is one rough selection, two sweeps, and four selections. The process flow is shown in Figure 1. The ore grade of the ore is 0.38%. In recent years, due to the increased depth of mining, the ore properties have changed. The grade of flotation molybdenum concentrate is 35.30% (annual accumulation), and the recovery rate is 73.68% (annual accumulation). Due to the instability of production, sometimes tailings The molybdenum grade is as high as 0.15%, causing a serious loss of molybdenum metal. After on-the-spot investigation and analysis, the main problems are: (1) due to the increased mining depth, there are many types of ore minerals, and the inter-mineral embedded relationship is more complicated; (2) the ore minerals in the ore are seriously altered, and the muddy minerals are easy to be muddy. The sericite, chlorite, kaolin, etc. increase, and the fault mud, so the degree of muddy in the ore is higher; (3) due to the finer grain size of the molybdenum ore, only a section of grinding is carried out in the production, which is not coarse Concentrate re-grinding to dissociate effective molybdenum ore; (4) partial molybdenite crystallisation is poor; (5) no sludge dispersant and inhibitor are used in on-site production; (6) on-site flotation The shorter time affects the uplift of molybdenite.

Figure 1 on-site production process

Third, flotation test

(1) Test of rough selection conditions

The recovery rate of rough selection operations plays a decisive role in the indicators of the whole test. Whether the selection conditions of rough selection operations are appropriate will affect the quality of the test indicators. To this end, detailed grinding and fineness, slurry pH, water glass dosage, flotation time, collector dosage, and foaming agent dosage were studied in detail.

1. Influence of grinding fineness on coarse selection index of molybdenum

The appropriate grinding fineness is determined by the embedding properties of the useful minerals in the ore. The finer the inlay, the higher the required fineness of the grinding. Production practice has proved that the flotation effects of different granular grades are different. In order to meet the requirements of the flotation process, the fineness of the grinding should be such that the useful minerals and gangue minerals basically reach the monomer dissociation, minimize the continuous body and avoid excessive pulverization. Grinding fineness test uses a rougher, time of 5min, the amount of lime 1000g / t, the amount of coal oil 150g / t, the amount of pine oil 40g / t. According to the experimental study of different grinding fineness, the influence of grinding fineness on the coarse selection index of molybdenum is shown in Figure 2.

Fig. 2 Effect of grinding fineness on coarse selection index of molybdenum

2. Influence of pH value of slurry on coarse selection index of molybdenum

The experiment uses lime to adjust the pH value of the slurry. The test uses one rough selection, flotation for 5 min, grinding fineness of -75 μm, accounting for 65%, water glass, 1000 g/t, kerosene, 150 g/t, pine oil, 40 g/t, pulp pH. The effect on the floatability of molybdenum minerals is shown in Figure 3.

Fig. 3 Effect of pH value of slurry on coarse selection index of molybdenum

It can be seen from Fig. 3 that as the pH of the slurry increases, the molybdenum grade of the molybdenum coarse concentrate decreases significantly, while the molybdenum recovery rate does not change much. From the point of view of flotation phenomenon, the pH of the pulp is increased, the foam is sticky, and the amount of mud in the coarse concentrate is increased, which is not conducive to the selection and improvement of the molybdenum grade. Therefore, it is determined that the pH of the slurry is neutral (the amount of lime is 1000 g/t).

3. Influence of water glass dosage on coarse selection index of molybdenum

Due to the large amount of muddy minerals in the ore, a large amount of slime will be produced during the crushing and grinding process. The presence of the slime will seriously affect the flotation effect of the molybdenum minerals. Therefore, it is necessary to investigate the amount of dispersant (usually used water glass). . The test adopts one rough selection, flotation 5min, grinding fineness -75μm accounted for 65%, lime 1000g/t, water glass variable, kerosene 150g/t, pine oil 30g/t, water glass dosage to molybdenum rough selection index The impact is shown in Figure 4.

Fig. 4 Effect of water glass dosage on coarse selection index of molybdenum

It can be concluded from Fig. 4 that the addition of water glass to the slurry can play the role of dispersing the slime and inhibiting the gangue minerals, and is beneficial to improve the grade of the molybdenum concentrate.

4, flotation time inspection test

In order to determine the flotation time of rough selection of molybdenum, the flotation time is investigated. The test process is shown in Figure 5. The test results are shown in Table 5.

Figure 5 Floating wash time test process

Table 5 Flotation time test results %

From the test results in Table 5, the crude molybdenum concentrate yield was 3.90%, the molybdenum grade was 8.46%, and the molybdenum recovery rate was 80.78%. The crude molybdenum concentrate yield was 5.90% and the molybdenum grade was 5.92%. The molybdenum recovery rate reaches 85.48%; the flotation time increases again, the molybdenum recovery rate increases less, and the molybdenum grade is lower, so it is appropriate to determine the rough selection time of 5 min.

5. Influence of the amount of collector on the coarse selection index of molybdenum

The collector is selected from commonly used kerosene. The test uses a rough selection of 5 min, grinding fineness -75 μm, 65%, lime 1000 g/t, water glass 1500 g/t, kerosene variable, pine oil 40 g/t, one rough selection. The effect of the amount of collector on the coarse selection index of molybdenum is shown in Figure 6.

Figure 6 Effect of kerosene dosage on coarse selection of molybdenum

6. Effect of the amount of pine oil on the coarse selection index of molybdenum

The amount of pine oil used was 5 minutes for rough selection, 65% for grinding fineness -75μm, 1000g/t for lime, 1500g/t for water glass, 175g/t for kerosene, variable for pine oil, and the amount of pine oil for rough selection of molybdenum. The impact of the indicator is shown in Figure 7.

Fig. 7 Effect of the amount of pine oil on the coarse selection index of molybdenum

It can be seen from Fig. 7 that with the increase of the amount of pine oil, the yield of molybdenum coarse concentrate is obviously increased, and the recovery rate of molybdenum is improved, but the growth trend is gradually reduced.

(2) Selective test after regrind

1, regrind test

The grain size of molybdenum ore in the ore is relatively uniform in each grain size, but the distribution of fine-grained grade (-38μm) is relatively large, accounting for 23.35%, which should be uniformly embedded in fine particles. In order to improve the molybdenum grade in molybdenum concentrate, it is the key to improve the monomer dissociation degree of molybdenum minerals, and also consider the negative impact of the increased mud on the flotation index, so the regrind inspection test was carried out. The test procedure is shown in Figure 8, and the test results are shown in Table 6.

Figure 8 Regrind test procedure

Table 6 Regrind test results %

From the results of Table 6, it can be seen that the molybdenum concentrate has a low molybdenum grade of 26.85% when it is no longer ground. It is difficult to make the molybdenum concentrate containing molybdenum grade more than 45% by selection; the regrind fineness is -38μm. When 84% is increased to 88%, the molybdenum grade is increased from 34.39% to 37.81%, which is a large increase, while the molybdenum recovery rate is reduced from 58.97% to 57.59%, with a small decrease; the regrind fineness -38μm is increased from 88% to 92%. At %, the molybdenum grade increased from 37.81% to 38.67%, with a small increase, while the molybdenum recovery rate decreased from 57.59% to 54.11%, a large drop. Therefore, the test determined that the regrind fineness -38 μm accounted for 90%.

2. Influence of the amount of collector after coarse refining on the selected index of molybdenum

In the results of the regrind test, the yield, molybdenum grade and molybdenum recovery rate of Jingwei 2 were higher, and should be captured. Therefore, the kerosene dosage test of the collector after regrind was carried out. The test flow is shown in Figure 8. The effect of collector kerosene on molybdenum selection indicators is shown in Figure 9.

Figure 9 Effect of kerosene dosage on molybdenum selection index

3. Influence of selected water glass dosage on molybdenum selection index

Due to the presence of muddy minerals in the ore, the effect of water glass on the selected indicators of molybdenum was investigated in a selection test. The test flow is shown in Figure 8. The effect of water glass usage on molybdenum selection indicators is shown in Figure 10.

Figure 10 Effect of selected water glass dosage on molybdenum selection index

It can be seen from Fig. 10 that as the amount of water glass increases, the molybdenum grade increases, but the molybdenum recovery rate decreases significantly, so the test determines that the amount of water glass is 300 g/t.

(3) Comprehensive open circuit test

According to the test results of the above conditions, the optimal conditions suitable for the ore's ore properties are determined for comprehensive open circuit tests. The test process is shown in Figure 11, and the results of the comprehensive open circuit test are shown in Table 7.

Figure 11 Integrated open circuit test process

Table 7 Comprehensive open circuit test results %

From the results of Table 7, it is seen that the comprehensive open circuit test obtains molybdenum concentrate containing 48.06% of molybdenum and 48.59% of molybdenum recovery.

(4) Closed circuit test

A closed circuit test is performed on the basis of a comprehensive open circuit test. The test process is shown in Figure 12, and the closed-circuit test results are shown in Table 8.

Figure 12 Closed circuit test process

Table 8 Closed-circuit test results %

(5) Industrial production practices

In order to enable industrial production to achieve better indicators and production stability, the on-site production process has been technically modified. The process flow after the transformation is shown in Fig. 13 using the original ore one-stage grinding, one rough selection, one rough selection, one coarse concentrate re-grinding, three sweeping, and re-grinding. After one year of production and operation, the production index is stable, and the molybdenum grade of molybdenum concentrate has reached 46.52% and the recovery rate has reached 78.78%.

Figure 13 Production process after transformation

Fourth, the conclusion

There are many kinds of molybdenum minerals, and the mineral inlay relationship is more complicated. The most distributed metal minerals are pyrite, followed by molybdenite, and other metal minerals are less. The non-metallic minerals contain the most quartz, followed by sericite. , feldspar, biotite. The particle size of molybdenum ore in the ore is relatively uniform in each size, but the distribution of fine-grained grade (-38μm) is more than that of fine-grained particles. This property requires fine grinding.

Molybdenum ore is mostly distributed in the cracks and holes of gangue in the form of plates, slats, strips, short veins and flakes. Some molybdenites have poor crystallinity and the aggregate particles are ambiguous; some molybdenite It is distributed in the star-like and muddy soils of altered sericite, chlorite and other minerals. The grain boundary is extremely unclear; in the molybdenite, fine particles containing pyrite and gangue minerals are common, and the latter two are produced. The molybdenum ore is generally difficult to dissociate, and the ore also contains a small amount of graphite. These properties all result in a relatively low molybdenum grade and recovery of the molybdenum concentrate.

After the ore dressing test, the coarse concentrate re-grinding was determined, and the number of selected operations was increased. The small-scale test technical indicators were: molybdenum concentrate molybdenum grade 45.23%, molybdenum recovery rate 77.09%; industrial production molybdenum concentrate grade reached 46.52 %, the recovery rate reached 78.78%, which has created greater economic and social benefits for the company.