Processing of molybdenum ores
The process of separating and enriching molybdenum minerals from molybdenum- containing ores. Mineral products molybdenum concentrate for smelting molybdenum alloy steel, molybdenum, molybdenum based alloys and chemical products.
Mineral resources of nature and molybdenum minerals are more than 30 kinds of industrial interest molybdenum minerals are molybdenite, molybdenum, tungsten, followed by calcium ore, lead ore color molybdenum, iron, molybdenum, China, etc. (see table). The molybdenum ore industry type has a single molybdenum ore, copper molybdenum ore, tungsten molybdenum ore, uranium molybdenum ore, and molybdenum-containing polymetallic ore. China's molybdenum resources are abundant and its reserves are among the highest in the world. The distribution of molybdenum mines is very wide, mostly concentrated in Shaanxi, Henan, Jilin and Liaoning provinces. The main molybdenum mines include Shaanxi Jinduicheng molybdenum mine, Liaoning Yangjiazhangzi molybdenum mine and Henan Luanchuan molybdenum mine. The characteristics of China's molybdenum mines are low grade, symbiotic mines and large reserves, mainly for underground mining. In addition, the world's molybdenum mines are mainly concentrated in the Cordillera Mountains in North and South America. Important molybdenum-producing countries include the United States, Canada, Chile, Peru, Mexico, Russia, and Armenia.
The process according to the molybdenum mineral hardness is small, the inlay size is fine, but the floatability is good. The molybdenum ore beneficiation mostly adopts the stage flotation and the selected process flow. The beneficiation process of molybdenum ore is divided into two types: single molybdenum ore beneficiation and molybdenum-containing polymetallic symbiotic ore beneficiation.
The single molybdenum ore beneficiation adopts a closed-circuit grinding rough selection, and the coarsely selected tailings are discharged through 2 to 3 sweeps to discharge the final tailings. After coarse grinding of the concentrate, the molybdenum concentrate is selected (4-12 times).
The molybdenum-containing polymetallic symbiotic ore beneficiation adopts different beneficiation processes according to the optional differences of associated minerals. Copper-molybdenum symbiotic ore mostly adopts copper-molybdenum mixed flotation, discards a large number of tailings, and the process of copper and molybdenum separation after mixing the concentrate and re-grinding; molybdenum-tungsten symbiotic ore, associated scheelite ore is preferential flotation, associated with wolframite The combined process of flotation re-election; the molybdenum-uranium symbiotic ore generally adopts a flotation-water-smelting combined process. Flotation is an effective method for recovering molybdenite and separating molybdenum minerals and associated metal minerals. Flotation the hydrocarbon oil (coal oil, transformer oil) as collector, pine oil, xylenol, higher fatty alcohols used as blowing agent. Inhibitors associated with sulfide ore are sodium cyanide, sodium sulfide, and Nokes. When the ore contains Mo 0.09% to 0.3%, the selected molybdenum concentrate molybdenum grade is 47% to 55%, and the recovery rate is 80% to 90%. The third ore dressing plant of the typical mineral processing plant Jinduicheng Molybdenum Company is located in Hua County, Shaanxi Province, China. It was put into operation in 1984 and its production scale is 15,000 t/d. It is the largest molybdenum ore selection plant in China. The main metal ores molybdenite minerals, followed by magnetite, chalcopyrite and galena, sphalerite, cassiterite bismuthinite and the like. Gangue minerals are quartz, feldspar, followed by fluorite, white mica, black mica, silk marble, calcite. The ore dressing process consists of three parts: crushing, rough selection and selection; broken into three sections and one closed road; rough selection is one rough selection, second selection, and second sweeping; selected as a section of re-grinding, nine selections . The original ore molybdenum grade is 0.118%, the concentrate molybdenum grade is 46.87%, and the recovery rate is 80.66%.
The Xiaosigou copper-molybdenum ore dressing plant is located in Pingquan County, Hebei Province, China. It was completed in 1971 and has been expanded and rebuilt several times. In 1991, the production scale reached 3000t/d. The Xiaosigou ore is a vein-infiltrated porphyry copper-molybdenum ore. The main gold 244 minerals are molybdenite, pyrite, chalcopyrite, followed by sphalerite, chalcopyrite, porphyrite and galena. The gangue minerals are mainly quartz and feldspar, followed by sericite, muscovite and chlorite. The beneficiation process consists of three sections and one closed road crushing ore, copper-molybdenum mixed flotation, and copper-molybdenum separation flotation process. The products are molybdenum concentrate and copper concentrate. 1987 indicator: the original ore contains Mo0.064%, containing CuO. 129%; antimony concentrate contains Mo46.67%, the recovery rate is 74.96%; copper concentrate contains Cul6.15%, the recovery rate is 50.91%.
The beneficiation method of molybdenum ore is mainly flotation, and the recovered molybdenum mineral is molybdenite. Sometimes in order to improve the quality of molybdenum concentrate, remove impurities, and then carry out chemical beneficiation of molybdenum concentrate. The molybdenite crystal is a hexagonal layered or plate-like structure formed by the S-Mo-S structure along the interlayer of Fanshijian and the polar covalent bond S-Mo in the layer. The bond between the layers is weak, and the covalent bond bonding within the layer is very strong. Therefore, molybdenum ore is easily disintegrated along the structural layer to produce flake or plate, which is the reason why the copper ore is naturally floatable. Practice has proved that under suitable grinding fineness, the dissociation of molybdenum crystal occurs between the S—Mo—S layers, and the hydrophilic S—Mo surface accounts for a small proportion. However, when over-grinding, the proportion of S-Mo surface increases, and the floatability decreases. Although a certain amount of polar collectors such as xanthate are added at this time, it is beneficial to the recovery of molybdenum ore, but the new slime produced by over-grinding Affect the flotation effect. Therefore, the selection of molybdenite should avoid and prevent over-grinding. In the production, it is necessary to adopt segmental grinding and multi-stage sorting process to gradually achieve monomer dissociation and ensure high recovery of molybdenum concentrate. The crushing of molybdenum ore generally adopts a three-stage and one-closed process, and the final product has a particle size of 12 to 15 mm. Grinding is usually carried out using a ball mill or a rod mill-ball milling process. Henderson is the only semi-self-grinding process. Flotation uses the preferred flotation method. Rough selection of molybdenum coarse concentrates, coarse sweeping of tailings to recover associated minerals or disposal. The molybdenum coarse concentrate is re-milled in two or three stages, and the final molybdenum concentrate is obtained in four or five times. The flotation agent of molybdenum ore uses a non-polar oil as a collector while adding a foaming agent. Surfactant Syntex is used as an oil emulsifier in the United States and Canada. Depending on the nature of the ore, lime is used as a conditioning agent, water glass is used as a gangue inhibitor, and sometimes cyanide or sulfide is added to inhibit other heavy metal minerals. In order to ensure the quality of molybdenum concentrate, heavy metal minerals such as copper, lead and iron contained in molybdenum concentrate and calcium oxide and carbonaceous minerals need to be further separated: sodium sulfide or sodium hydrosulfide, cyanide or ferricyanide is generally used. manufactured copper and iron; inhibition by weight of lead chromate or Knox (Nokes). If an inhibitor is used, the impurity content does not reach the quality standard, and it needs to be supplemented by chemical beneficiation: secondary copper sulfide is leached with cyanide; chalcopyrite is leached with ferric chloride solution; The galena is leached with hydrochloric acid and ferric chloride solution to achieve a standard content. The gangue containing calcium oxide is easily muddy, so it is not necessary to over-grind the ore containing such gangue. Production is often added sodium silicate, sodium hexametaphosphate or an organic phosphate gel as gangue inhibitor or dispersant; Activated carbon can also be added CMC (carboxymethylcellulose) inhibition carbonate gangue. Finally, it can be leached by hydrochloric acid or hydrochloric acid plus ferric chloride solution. For the separation of carbonaceous minerals, it is first necessary to find out that the carbonaceous material is graphite , asphalt or coal. The floatability of these carbonaceous minerals is similar to that of molybdenum ore, but the density is small, and it can generally be removed by re-election; using hexapoly-sodium metaphosphate and CMC to suppress molybdenum float; or adding ferric chloride or water glass It is also effective to inhibit carbonaceous material with sodium hexametaphosphate; it is also one of the methods to remove organic carbon by roasting. It should be noted that the separation of all these carbonaceous minerals is currently unsatisfactory and is still a problem that has not yet been fully resolved. The SiO2 (silica) content in the gangue is too high, which is often the reason for affecting the grade of molybdenum concentrate. It has been determined that the SiO2 content decreases with the increase of the grade of molybdenum concentrate, and there is a tendency for mutual consumption. As long as the molybdenum mineral reaches the monomer dissociation fineness, the SiO2 content can generally fall below the standard. Adding activated carbon to the oil on the molybdenum surface, and adding CMC to inhibit the silicate gangue, the SiO2 content can also be reduced below the standard.
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