Research progress on molybdenum ore beneficiation process

I. Introduction

Modern mineral processing projects are developing in the direction of increasing resource utilization, expanding available resources and recycling resources. E.g. beneficiation - Bayer Xuanye new technology enables the largest non-ferrous metal of aluminum may utilize resources extended from less than 10 years to 40 years, sulfide ore biological new metallurgical technology can reduce the available copper grade copper ore About 20% to 40% can increase the available resources of copper mines in China by more than two times. The flotation- molybdenum blue method can effectively utilize the molybdenum oxide ore with large reserves, and the low-grade molybdenum concentrate-oxygen oxidation method can increase the availability of some difficult-to-select high-oxidation molybdenum ore by 15%.

In recent years, traditional beneficiation processes are facing challenges. Many research institutes and institutions have introduced many resources to utilize high-tech molybdenum-selecting processes and combined metallurgy processes through years of research. The breakout of these processes is very eye-catching.

These new processes are compared with traditional coarse grinding and rough selection, re-grinding, copper-molybdenum ore mixed flotation and simple copper-molybdenum separation. It is unique, delicate and innovative. It is inevitable.

Second, no collector flotation - flotation process

Amax's Deepak.Malhotra et al ^{[1 ~ 3]} developed a new process for flotation of molybdenite with no collector flotation molybdenum ore, coarse tailings and strong collector.

The molybdenum ore containing Mo 0.18%, FeS ₂ 2.2%, Cu 0.007%, Pb 0.003%, and Zn 0.012% is ground in a ball mill to P80=100 μm without adding any molybdenite collector. vapor oil, diesel oil, and coal, adding only MIBC frother methyl isobutyl carbinol After rough selection, a coarse concentrate containing about 11% of Mo is obtained, the recovery rate of coarsely selected coarse concentrate molybdenum is 76.8%, and the coarse concentrate is re-grinded by 3 sections of gravel mill and 5 times of selection. A total of 140g/t of water glass was added, and the selected tailings contained Mo0.4% and were discarded. 5 Featured concentrate containing MoS ₂ 97.5% ~ 98%, and small amounts of iron sulfide-containing impurities, the final concentrate grade molybdenum disulfide lubricants, grinding by a jet mill to 0.5 ~ 1μm product.

The lubricant-grade molybdenum disulfide produced by the flotation-free flotation is leached with hydrochloric acid-hydrogen acid after the molybdenum concentrate selected from diesel or steam oil, and then washed with alkali to produce the lubricant grade II. Molybdenum sulfide (manufactured by Mitex) has a much lower C content, usually not more than 0.7%, and other impurities such as Fe, MoO ₃ and oil are also relatively low. It is well known that at present, the molybdenum concentrate selected by kerosene flotation is used for the production of lubricant-grade molybdenum disulfide precursor. The molybdenum concentrate is generally in the range of 2% to 4%. This hydrocarbon oil is used in the preparation of lubricant molybdenum disulfide. Can be converted to carbon. Not transferred

Carbonized hydrocarbon oil is also present in the lubricant. This part of the oil is generally 0.05% to 0.3%. Carbon and oil severely reduce the tribological properties of the lubricant grade molybdenum disulfide. High carbon and oil lubrication. The agent is not an excellent lubricant additive. In addition, molybdenum concentrates produced by flotation without collectors are also less expensive to produce lubricant grade molybdenum disulfide.

The tailings without flotation flotation will be larger and the area ratio will be larger. The molybdenum ore will be more complete and the molybdenum ore will be selected. In general, the part of the tailings Molybdenum ore is a fine-grained refractory molybdenite with poor floatability, such as molybdenum ore below -38 μm.

Amax's researchers use a collector with a higher recovery capacity than steam oil, and a more expensive mixture of dodecyl mercaptan and tetradecyl mercaptan, that is, a mixture of C12H23SH and C14H27SH flotation. First, coarse selection is carried out, and the coarse concentrate is re-selected after 1 or 2 times. The tailings are coarsely selected, and the selected tailings are also discarded. The selected copper-bearing molybdenum concentrate is used to suppress copper. (with sodium hydrosulfide), flotation molybdenum ore, and then selected 1 or 2 times to obtain the final molybdenum concentrate, which contains Mo55.8%, Cu<0.1%, and SiO2<3%.

It should be noted here that although the mixture of dodecyl mercaptan and tetradecyl mercaptan has higher ability to capture molybdenite than steam oil or diesel, their dispersibility in the slurry is poor. The thiol collector is emulsified, and the commonly used emulsifier is a polypropylene glycol or a polyethylene glycol surfactant.

Part of the non-collector flotation, flotation tailings with strong collector flotation process shown in Figure 1.

Figure 1 Part of the collector-free flotation process

Only use 18g/t foaming agent, adjust the pH value of the pulp to 8 or less with lime, and the coarse selection result of no collector flotation molybdenum ore is shown in Table 1.

Table 1 Results of rough selection of collector-free flotation molybdenum ore

The data in Table 1 shows that the molybdenum ore is ground to P80 = 100 μm. In the weakly alkaline (lime) medium, it is feasible to carry out the collector-free flotation with only the foaming agent. The molybdenum is enriched 60 times. 3/4 of the molybdenite is floated into the foam product and the results are ideal. It has also been confirmed that this part of the coarse concentrate can be re-grinded to obtain lubricant-grade molybdenum disulfide contaminated with hydrocarbon oil such as steam oil or diesel, while saving a part of the hydrocarbon oil.

The tailings of the non-collector flotation molybdenite are re-flotted with various collectors. The flotation results are shown in Table 2.

Table 2 Results of re-flotation test of various collectors for non-collector flotation tailings

The results in Table 2 show that the non-collector flotation tailings with the strong collector dodecyl mercaptan and dodecyl mercaptan mixture has the highest recovery rate of molybdenum. After the coarse concentrate is re-grinded, the molybdenum concentrate grade contains Mo 52.8% and the molybdenum recovery rate is 98.9%.

Third, the talc-containing copper-molybdenum ore flotation process

Martinc.kuhn et al ^[4] introduced a new flotation process containing talc copper-molybdenum ore, which is completely different from the traditional process, very novel, and the flotation index is significantly improved.

The copper-molybdenum ore contains Cu 0.64%, Mo 0.013%, Fe 6.35%, and Mg 1.7%. Copper ore was mainly chalcocite, covellite, chalcopyrite and bornite, pyrite iron minerals, pyrrhotite and pentlandite, gangue minerals quartz, feldspar further containing a relatively large amount of buoyant layered minerals talc and sericite, molybdenum ore was present molybdenite, dip moderate size.

The ore is ground to P80 = 150 μm and the slurry concentration is 35% to 40%. Flotation of copper-molybdenum minerals with the following flotation reagents:

Copper mineral collector such as copper ore: potassium sulfonate xanthate 10g/t

Accelerator: AEROFLOAT-23812g/t

Molybdenum collector: diesel 19g/t

Foaming agent: AF-6547～100g/t

Foaming agent: methyl isobutyl methanol 32 ~ 72g / t

pH adjuster: lime, pH 10~10.5

Copper and molybdenum separation flotation reagent:

Molybdenite and talc inhibitor: CMC15～40g/t

The steam was heated to 65 ° C for 1 h.

The process of copper-molybdenum ore beneficiation is shown in Figure 2. The process flow diagram comprises: grinding a copper-molybdenum ore containing 0.64% of Cu and 0.013% of Mo to P80=150 μm, and then performing copper-molybdenum mixed flotation with potassium pentyl xanthate and diesel, and the obtained crude is obtained. After the concentrate is re-grinded to 80% of 0.038mm, the lime is used to suppress the associated pyrite, and the copper-molybdenum sulfide ore is re-selected once. The coarse-choice tailings and selected tailings are discarded and sent to the tailings pond.

Figure 2 Copper and molybdenum ore dressing process flow chart

1 Discover crude concentrate buoyant main component is layered silicate, magnesium silicate, talc copper sulphide minerals such as chalcocite, chalcopyrite and molybdenite with a small amount of molybdenite and the like. Add CMC carboxymethyl cellulose 15～40g/t, stir to adsorb the carboxymethyl cellulose molecules on the surface of molybdenum ore, and then perform 1 selection of copper. The floating copper and molybdenum inhibit the talc, once selected. The concentrate is further mixed with CMC and then subjected to copper extraction twice to obtain a copper concentrate containing Cu 39.9% and Mo 0.029%. One copper selection and two copper-selected tailings are combined into a stirred tank to pass steam at 90 °C for 30-60 min to desorb the CMC adsorbed on the surface of the molybdenum ore before the flotation operation and lose it. The activity is followed by a molybdenite collector and a small amount of foaming agent for one molybdenite flotation, and then one sweep, and the foam is returned to the regrind operation.

The primary molybdenum concentrate still contains a certain amount of easy-to-float talc. In order to suppress this part of talc, a small amount of sulfuric acidified pulp is added to the concentrate at a pH of 1.3 to 1.9 to inhibit talc, and 2 times of molybdenum after acidification. Selected, 2 times molybdenum selected tailings are mainly talc, but it is still difficult to suppress in the 2nd molybdenum selected foam. For further separation of talc and molybdenite, the selected concentrate is baked at 250 °C for 30~ 40min, the diesel oil adsorbed on the surface of molybdenum ore is removed, and the light burning can also lightly oxidize the surface of the molybdenite particles to form a molybdenum oxide film, so that the floatability of the molybdenum ore is reduced, and the concentrate after light burning is added. Isobutyl butyl flotation talc, talc flotation tailings, alkali adjustment pH to about 9, and then the last selection to obtain molybdenum concentrate, the molybdenum concentrate containing Mo55.64%, Cu3.68% The total recovery rate of molybdenum is about 85%. The last time the molybdenum-selected tailings were returned to the coarse concentrate for re-grinding. Although the molybdenum concentrate contains 3.68% Cu, the quality of the molybdenum concentrate is high, and the molybdenum concentrate contains Cu, which may be due to the better floatability of the chalcopyrite in the copper-molybdenum ore.

In the process, the separation of molybdenum ore and talc is first inhibited by CMC, then the molybdenum ore is inhibited to inhibit talc, and then the molybdenite flotation talc is inhibited. This process separates the two.

Fourth, BinghamCanyo selection and metallurgy joint process

The Bingham Canyon copper-molybdenum deposit in Utah is a large copper-molybdenum deposit in the world. It is also a porphyry copper-molybdenum ore. The copper minerals in the ore are mainly chalcopyrite and molybdenum ore. Associated minerals, and the ore contains a large amount of sericite. Easy-floating minerals such as talc, although the ore contains 0.6% to 1.5% of Cu and 0.03% to 0.04% of Mo, the grain size of the molybdenum ore is finer, and the grinding grain size P80 is 74 μm. The ore is easy to be muddy, and the sericite and talc content is large, which is a difficult choice of copper-molybdenum ore.

The traditional mineral processing process is as follows:

Copper-molybdenum ore is ground to P80=74-100μm, and then used isopropyl xanthate, diesel collector and methyl isobutylmethanol as foaming agent, lime as adjusting agent, first select copper-molybdenum mixed coarse The ore is then separated from copper and molybdenum, sodium sulfide is used to inhibit copper sulfide ore such as chalcopyrite, and molybdenite is floated with diesel.

The copper-molybdenum mixed concentrate contains Cu 27.5% and Mo 1.8%. After copper and molybdenum separation, the tailings are copper concentrate containing Cu>30%. Sent to the copper smelter to recover copper. Separation of copper and molybdenum to obtain molybdenum coarse concentrate, dehumidification with hydrocyclone, overflow of cyclone and copper concentrate, cyclone bottom flow for several times of molybdenum selection, selected tailings returned to copper and molybdenum separation Selection, selected concentrates after filtration, drying, light burning, pulping, anti-flotation talc with foaming agent, talc (including partial copper) and copper concentrate merged into copper concentrate, reverse flotation tailings for the final Molybdenum concentrate, the process flow chart is shown in Figure 3.

Figure 3 BinghamCanyon copper and molybdenum concentrator flotation process flow chart

Because BinghamCanyon copper-molybdenum ore contains a large amount of easy-to-float talc and sericite, the impregnated granules are fine and difficult to select. The single flotation and reverse flotation process is used to float Mo52 from ore to molybdenum concentrate. 3% of molybdenum concentrate, the total recovery of molybdenum is only 50.55%, and the industrial molybdenum oxide roasting stage produced by roasting produces 57.3% of industrial molybdenum oxide with Mo content, the total recovery of molybdenum is only 49.9% (oxidation) The molybdenum recovery rate of the calcination operation was 98.71%). It should be said that the recovery rate of molybdenum is low, and the researchers proposed a flotation hydrometallurgical combined process. In the process, the copper-molybdenum mixed concentrate is subjected to rough selection to obtain a low-grade molybdenum concentrate containing 15.7%, Cu 3.8%, and S14.4% for oxygen pressure oxidation treatment, and finally the molybdenum product is pure molybdenum trioxide. . The combined process of flotation-oxygen oxidation is shown in Figure 4.

Figure 4 BinghamCanyon process and metallurgy joint process flow chart

V. Flotation-oxygen oxidation process

There are many copper-molybdenum ores in the world, such as the extra large Bingham copper-molybdenum mine with a copper reserve of tens of millions of tons in the United States, the extra-large Chuquika motor copper-molybdenum mine in Chile, and the extra-large porphyry copper in China. Molybdenum Dexing Copper Mine, Wunuge Tutong Molybdenum Mine, and many small and medium-sized copper-molybdenum mines, such as the Olajite Copper-Molybdenum Mine in Bulgaria.

When selecting such copper-molybdenum ore, the copper-molybdenum mixed concentrate is usually floated with xanthate and diesel, and then the copper mineral is inhibited by hydrosulfide, such as NaHS, and the molybdenite is floated with diesel, due to suppression. Copper minerals account for a large mass ratio of copper-molybdenum mixed concentrates, and the following reactions occur when copper minerals are inhibited:

2CuX+HS ^- +OH ^- →CuS↓+H ₂ O+2X ^-

Wherein X represents ROCSS ^- like xanthate.

Years of research and practice have shown that a large amount of xanthate is adsorbed when copper sulfide minerals such as chalcopyrite are floating, forming a surface film of copper xanthate with a positive solubility, and desorbing the HS ^- based solution by hydrosulfide dissociation Consuming a large amount of HS ^- , the general dosage should be as high as 10kg / t or more. Like the Bulgarian copper and molybdenum plant, when the molybdenum is selected, the NaHS dosage is as high as 17.2kg/t, accounting for 62% of the total cost of the chemical, which not only increases the ore dressing cost. Large, at the same time the concentrating plant air odor and serious environmental pollution. In addition, when sodium sulphide is added, the molybdenum concentrate after separation of copper and molybdenum still has a high molybdenum content, generally 0.5% to 2%, and the molybdenum concentrate of the selected molybdenum plant contains 3% copper, which wastes copper resources.

Based on the above situation, JONES.DL ^[6] proposed a new process to treat 0.5% to 10% of molybdenum concentrate containing Cu. The process is flotation-oxygen-oxidized molybdenum concentrate, and the copper concentrate separated by copper-molybdenum is also treated by oxygen pressure oxidation. The process flow is shown in Figure 5.

Figure 5 Flow chart of copper-molybdenum ore flotation-oxygen oxidation process

The flotation-oxygen oxidation process includes: after crushing and grinding the copper-molybdenum ore, using lime as a adjusting agent, a mixture of xanthate collector and diesel, and foaming with methyl isobutyl methanol and isooctanol. The agent floats out the copper-molybdenum mixed concentrate.

A sulfide mineral inhibitor using sodium hydrosulfide as copper to enhance the inhibitory effect of sodium hydrosulfide on copper sulfide ore, and reduce the amount of sodium hydrosulfide to prevent a rapid decrease in the potential of copper-molybdenum flotation slurry (generally from -600 mV -200mV) into the flotation operation (flotation tank) is filled with industrial nitrogen, after copper and molybdenum separation, two products are obtained, namely molybdenum concentrate containing Mo40%~50%, Cu0.5%~10% and a small amount Copper concentrate containing about 28% of Cu, depending on the grade of copper ore and the type of copper sulfide mineral.

The molybdenum concentrate containing mo45.2%, Cu3.6%, Fe3.6%, and all S34.2% selected from molybdenum is adjusted to a slurry containing 500 g/L of solid, and added to the slurry. 15g/LCu, 12g/LCl of copper chloride and 20g/L of acid were oxidized at 150 ° C and 1480 kPa for 1 h under oxygen pressure. After oxygen pressure oxidation, the slurry was discharged from the autoclave, filtered, and the filter cake was washed and the filtrate was filtered. The pH was 0.91, and the filtrate contained Cu31.34g/L, Mo3.64g/L, Fe5.87g/L, copper leaching rate of 96.2%, and molybdenum leaching rate of 1.6%. The filtrate is combined with the copper oxide oxygen oxidation product, the copper is enriched by solvent extraction, and the copper sulfate solution is decollected. After purification, the copper is electrolyzed, the copper extractant is made of hydroxyindole, the solvent is kerosene, and the copper phase is extracted. A small amount of molybdenum is recovered.

The flotation-oxygen oxidation process can enrich the molybdenum concentrate containing 0.5% to 10% of Cu to a high-grade molybdenum concentrate containing about 0.1% of Cu, and a small amount of molybdenum in the copper concentrate, via oxygen. It is recovered after pressure oxidation. Unlike the high-temperature and high-pressure oxygen-pressure molybdenum concentrate, the oxygen oxidation temperature of the process is low, only 150 ° C, the pressure is low, only 1500 kPa, only a small amount of CuCl ₂ is consumed, and copper in CuCl ₂ can be recovered.

The flotation-oxygen oxidation process can treat high copper molybdenum concentrate, which can reduce the amount of NaHS used in flotation and reduce the production cost of copper and molybdenum separation.

In short, with the continuous development of science and technology, the advent of a new process of molybdenum ore beneficiation and smelting and smelting will further increase the utilization rate of expensive molybdenum resources and expand the available reserves of molybdenum resources, which deserves the attention of the industry.

references

[1] Deepak.Malhotra.Recover of molybdenite [P].US4606817.1986.

[2] Adriaan. Wiechers.Froth flotation p rocess and collectorcomposition [P].US 4221644.1980.

[3] Harris.R.Flotation of molybdenite [P].US 4.122004.1978.

[4] Martin.C.Kuhn.Methods for recovery of molybdenam[P].US 20080067112.2008.

[5] Balliett.RWProduction of puremolybdenum oxide fromlow grade molybdenite concentrates [P]. US20050019247.2005.

[6] David.L.Jones.Process for the treatment of molybdenumcencentrate [P].US 20030124040.

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