The search for molybdenum ore flotation collector

1. Flotation of molybdenum ore

(1) The floatability of molybdenum ore

Molybdenum ore, or molybdenum disulfide, is the most common and important molybdenum-containing mineral in the world's molybdenum supply. Molybdenum ore (MoS ₂ ), which is a hexagonal or trigonal system, is a typical layered structural mineral. The figure below is a pure molybdenum ore selected from the Luanchuan molybdenum ore. This figure is an image magnified 1000 times under an electron microscope.

Molybdenum disulfide electron microscope image (1 × 10000)

The layered (or flaky) structure is clearly visible from the figure. The molybdenum ore layer is S-Mo-S surface, and the cleavage surface is very developed. Even if the molybdenum crystal is ground to a nanometer size by ultrafine grinding, the peak of the 001 plane or 002 cleavage plane shown by the X-ray diffraction pattern of the nanometer-sized mineral is still very obvious. The surface of the molybdenum ore surface is smooth, so that the molybdenum ore exhibits natural hydrophobicity and has good natural floatability.

On the other hand, the molybdenite crystal is anisotropic, that is, its layer is opposite to the facet, the layer is non-polar, the facet is polar, the molybdenum atom is exposed, and the facet is oxophilic and hydrophilic. Therefore, most ore miners have determined that the molybdenite surface determines the floatability of the molybdenum ore. The facet determines the E-potential of the molybdenum ore. The floatability of the molybdenite particles is controlled by the surface of the molybdenite. The larger the surface ratio, the better the floatability, and the E-potential determines the molybdenum floatability.

Of course, in the practice of flotation, the floatability of molybdenum ore is related to the embedding grain size of molybdenum ore, the oxidation rate of molybdenite surface, the type of symbiotic sulfide minerals, and the types of gangue minerals.

(2) Flotation of molybdenum ore

Based on research floatability of molybdenite, nearly half a century of research and practice shows that can be collectorless molybdenite flotation during flotation, oil-based oils available flotation collector can also be used Some sulfur-containing collectors are flotation.

Since the molybdenite surface layer is non-polar, so most of the oil collector with a concentrator, such as kerosene, diesel, light cycle oil, and oil vapor as molybdenite collectors.

Hydrocarbon oil such as kerosene is strongly adsorbed on the surface of molybdenite by Coulomb gravity, and the two attract each other very closely. Whether JINDUICHENG molybdenite concentrate or Luanchuan production of molybdenite concentrates contain large amounts of kerosene, molybdenum concentrate oil content of up to 3% to 6% (mass fraction). The molybdenum concentrate (about 6% oil) and Tween-80 were stirred vigorously for 30 min, and then filtered. The dried molybdenum concentrate contained a large amount of kerosene. The oily molybdenum concentrate was vigorously stirred with 10% acetone for 30 minutes to remove a portion of the adsorbed kerosene. In the United States Climax Molybdenum Company, the flotation of Mo-containing 54% molybdenum concentrate containing steam oil up to 6.53%, in the multi-hearth furnace roasting, the first furnace temperature is 345 ~ 400 ° C before the molybdenum concentrate The steam oil in it drops to 0.85%. It can be seen that kerosene and the like are strongly adsorbed on the surface of the molybdenum ore and the molybdenum ore is floated.

However, when using collectors such as steam oil (or diesel) and kerosene, the recovery rate of molybdenum in many molybdenum plants is not high, especially the crude recovery rate. For example, in some large-scale molybdenum plants in China, when the Mo content is 0.1%-0.15%, the crude recovery rate is about 82%-87%. Many molybdenum plants in Luonan area of ​​Shaanxi have a selected grade of 0.05%. ~0.06%, the molybdenum concentrate grade contains Mo≤42%, and the recovery rate is between 65% and 72%. A vanadium vanadium mine in southern Shaanxi, the ore contains Mo 0.06%, the inlaid grain size is 0.005-0.001mm, and the tongs and the biotite are densely symbiotic. When the ore is ground to 1000 mesh, 90%, when 200g/t kerosene is used for flotation The concentration of molybdenum coarse concentrate is difficult to reach 0.5%, and the molybdenum recovery rate is less than 20%.

Domestic molybdenum ore, molybdenum ore and sericite are densely symbiotic. Molybdenum ore contains 40% to 60% (mass fraction) of sericite. When kerosene is used as collector, the ore is 0.4% Mo and the recovery rate of molybdenum is less than 70%. In another molybdenum ore, the molybdenum ore and graphite or carbonaceous minerals are combined with cattle, and the selected grade contains Mo 0.4% to 0.6%. The kerosene is used as a collector, and the graphite is first floated with pine oil, and then the molybdenum ore is selected. The grade of molybdenum concentrate is difficult to reach 20%, and the recovery rate of molybdenum is less than 70%. When a molybdenum ores molybdenite dense symbiotic with monazite, kerosene as collector flotation agent, when molybdenum concentrate containing Mo 42.61%, monazite kerosene also adheres the molybdenum concentrate containing up to 0.48% phosphorus containing 2.42% lead.

In the flotation of many copper- molybdenum ores, the mixed preferential flotation method is adopted, that is, the xanthate collector or the trisulfide carbonate collector and the foaming agent are used to float the copper sulfide ore and molybdenite. Copper-molybdenum mixed concentrate, then use diesel or kerosene as collector to float molybdenum ore, use Nokes (diphosphorus pentasulfide and caustic soda reaction product) and a small amount of sodium cyanide to inhibit copper-bearing sulfide minerals, such as chalcopyrite and molybdenite For example, copper ore, etc., contains copper 0.4%, Mo 0.02% (most copper molybdenum ore copper and molybdenum grades), copper recovery of about 90%, molybdenum recovery of 40% to 60%, molybdenum recovery The rate needs to be improved. If molybdenum is enriched to 54%, the molybdenum recovery is about 30%.

Second, molybdenum ore flotation collector search

Although the natural floatability of molybdenite is good, the quality of molybdenum ore flotation and the recovery rate are determined by the developer's research depth of molybdenum ore process mineralogy, beneficiation process selection, equipment selection and pharmaceutical system. . However, most ore dressing scholars have turned their attention to the recovery rate of molybdenum and turned their attention to the collector of molybdenite.

Improving the recovery rate of molybdenum, in resource and environmental research and development projects, is a key issue supported by the state. It is estimated that a ton Molybdenum plant, if the recovery rate by 3 percentage points from 85% of its economic benefits will reach tens of millions, it is very important in the international price of silver is so high, but this precious resource molybdenum-time Especially important, but it is also a problem.

For a long time, in the practice of molybdenum ore dressing, as a collector of tongs, whether domestic or foreign, except for a few manufacturers, most manufacturers use diesel (or steam oil) and kerosene. However, recent laboratory studies have found that the recovery rate of many molybdenum collectors used in the test (under similar conditions of molybdenum concentrate grades) is higher than that of diesel. These collectors are:

1. Natural vegetable oil and synthetic oil. Such as cottonseed oil, rice bran oil, corn oil, soybean oil, coconut oil, castor oil, peanut oil and tung oil. There are also essential oils (EssentialOil) such as scented sesame oil, citronella oil, JOJO oil and camphor oil. Synthetic oils such as 2-butyloctyl oleate.

2. Sulfur-containing collector. Such as n-dodecyl mercaptan, tert-dodecyl sulfate, dodecyl mercaptan to tetradecyl mercaptan mixture, tert-dodecyl sulfate-styrene polyethylene glycol or trivinyl poly A glycol ether mixture, a dialkyl dithiophosphate, a trithiocarbonate, and the like.

3. Mixed collector. Such as vegetable oil collector and sulfur-containing collector mixture, diesel and sulfur-containing collector, cottonseed oil and methyl bisphenol xanthogen, isopropyl naphthalene and mercaptobenzothiazole sodium, Various types of sulfur-containing collectors, cottonseed oil and trithiocarbonate, isopropyl-based N-ethyl thiocarbonate (1sopro-pyl N-ethythiocabamate) and ethylene glycol.

It is well known that most natural vegetable oils and animal oils are mixtures of triglycerides of various fatty acids. Triglycerides are products of the reaction of carboxylic acids with glycerol. Vegetable oil is a mixture of various fatty acid glycerides, and its structural formula is as follows:

Wherein R, R' and R" represent different aliphatic hydrocarbon groups, respectively. Certain glycerides contain alcohol functional groups, contain aldehydes and alcohol functions. Coconut oil is a saturated oil or a highly saturated oil, and the content of double bond fatty acids Almost zero. Linseed oil is a fatty acid containing 18 carbon atoms, its content is very high, there are three double bonds in the molecule (the following table is expressed by C _{18 : 3} ), the chemical composition of some common natural oils is shown in Table 1. in.

Table 1 Composition of common natural vegetable oils ^[1]

* Iodine value, iodine 100g natural vegetable mass can absorb g. Indicates the degree of unsaturation of natural vegetable oils.

C _l8 represents a fatty acid ester having 18 carbon atoms. C _{18 : 3} indicates that there are 3 double bonds in the fatty acid of 18 carbon atoms, and so on.

(1) The original molybdenum ore float is selected from natural vegetable oil as a collector test

The collector performance test was carried out using certain natural vegetable oils and certain essential oils as molybdenite collectors. The test ore contains Mo 0.0638%, 1kg ore, which is ground to -0.425mm in 65% (solid) in a ball mill , 90% of each collector is added to the ball mill with 100g/t, and then ground into a single tank flotation machine. Add 40g/t foaming agent, stir for 2min, first float for 1min, get the first coarse concentrate, stir 1mm, float for 6min to get the second coarse concentrate (middle mine), analyze the coarse concentrate separately Grade and calculated molybdenum recovery, the results are shown in Table 2.

Table 2 Test results of molybdenite flotation collector

The results showed that in addition to the linseed molecular oil, the oils tested, the crude concentrate grade and the crude recovery rate, plus the sweeping grade and the total recovery of sweeping were higher than diesel. Among them, Austrian gas oil and peanut oil have higher harvesting efficiency.

Table 3 Test results of some essential oils as molybdenite collectors

The results show that many essential oils (essential oils) are used as collectors for molybdenite, and their collection performance and selectivity are much better than diesel, especially 2-butyloctyl oleate.

Copper molybdenum ore flotation collector test. Copper-molybdenum ore, containing Cu 0.259%, Mo 0.0064, ore after grinding to -0.15mm accounted for 60%, using lime to adjust the pulp pH to 10.5, mine plus 6g / t ethyl xanthate, 10g / t oil Collector, 25g/t foaming agent, stir for 2min, float for 6min, add 4g/t ethyl xanthate and then float. The test results are shown in Table 4.

Table 4 Results of flotation test of copper-molybdenum ore

The results showed that sodium xanthate and light cycle oil mixture or sodium ethyl xanthate and cottonseed oil and light cycle oil mixture were the best to select copper minerals and molybdenite.

(2) Using sulfur-containing compounds as molybdenum collectors to float molybdenum ore. There are various sulfur-containing collectors, of which dodecyl mercaptan or branched dodecyl mercaptan is A very important molybdenum collector.

The formula of the alkyl mercaptan is C _n H _{2n + 1} SH, wherein n = 12-16. Among them, n-dodecyl mercaptan or branched tetradecyl mercaptan or dodecyl mercaptan and tetradecyl mercaptan, or a mixture of thirteen to hexadecyl mercaptan is preferred. In the production practice, the amount of collector can be reduced after emulsification of dodecyl mercaptan, and the recovery rate of copper minerals and molybdenite can be improved.

The general formula of the floater is R ₁ -(O-R _2)m -OH

In the formula, R ₁ -phenyl, alkyl, alkyl-substituted benzene, hydrogen or a saturated heterocyclic group. R ₂ -alkylene RCH= and polyethylene glycol having a molecular weight of 50 to 2000.

The mixing ratio of dodecyl mercaptan to the emulsifier was used at 95:5 by volume of 90:10, 85:15 and 80:20. It is also possible to use dodecyl mercaptan in combination with potassium pentyl orthosilicate and polyethylene glycol. The Climax molybdenum ore was floated with dodecyl mercaptan.

The test method comprises a molybdenum ore containing Mo 0.18%, Cu 0.003%, Pb 0.012%, Zn 0.012%, FeS ₂ 2.2% and Ag 0.9 g/t, and is ground at a concentration of 60% in a rod mill to +100 mesh 35%. Then, the slurry was adjusted to 35% solids, and the pH was adjusted to 8 with lime. The l8g/t pine oil was added, stirred in a flotation machine for 3 minutes, and floated for 2 minutes. The crude concentrate contained Mo 11.06% and the yield was 1.25%. , the crude recovery rate is 76.8%, and the crude tailings are 0.042%. The crude tailings are used as raw materials, and steam oil (plus octox), dodecyl mercaptan mixture and pentyl xanthate Flotation was carried out for the collector, and flotation was carried out for 4 min. The results are shown in Table 5.

Table 5 Comparison table of various collector flotation results ^[2]

The results show that the recovery of molybdenum is significantly improved when using dodecyl mercaptan as a molybdenite collector compared with conventional collector vapor oil (plus a small amount of Xintex). The use of dodecyl mercaptan as a molybdenite collector for flotation of several molybdenum mines in China has also achieved similar effects, except that a small amount of activated carbon (1 g/t) is sometimes deactivated during the selection.

(III) Mixed collector flotation test

Copper molybdenum ore containing Cu 0.543% and Mo 0.014%. Grinding to -65 mesh accounts for 90%. Add lime to the straight grinding, adjust the pH to 10.8, and float in a Denver single tank flotation machine. Add 30g / t natural vegetable oil collector and other types of collector, the mixture foaming agent 20g / t. Stir for 2 min and float for 5 min. The test results are shown in Table 6.

Table 6 Test results of mixed collector flotation copper molybdenum ore

The results show that the copper molybdenum ore is distilled with 20% cottonseed oil, 20% dodecyl mercaptan, 20% dialkyl dithiophosphate, 20% sulfurized carbonate and 20% ethylene glycol. The flotation mixed collector copper molybdenum ore flotation results are better.

For some copper-molybdenum ore, natural vegetable oil, dodecyl mercaptan, dithiophosphate and thiocarbonate mixed collectors have better flotation effect.

Other studies have shown that for some copper-molybdenum ore, 65%, N-ethyl O-isoreylthiocarbonate, 5% mercaptobenzotriazole sodium and 30% diethylene glycol mixed collector The flotation effect is better. In summary, the study of collectors for molybdenite flotation collectors and copper-molybdenum ores, such as chalcopyrite, chalcopyrite, porphyrite and molybdenite, will continue to evolve with the development of science and technology, especially petrochemicals. With the continuous development and development, it is believed that through the efforts of the mineralogists, it will surely find a new molybdenite collector with better harvesting performance and better performance.

references

[1] Tom1. Yaung, Flotation of sulfide mineral species with oils [P]. USb, 827, 220.

[2] Deepak Malhotra, Recovery of molybdenite [P]. US 4606, 817.

[3] Heinrich Hesse, Collector for moll iran metal sulphid prepration 『P].US 2004/0099836.

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