Molybdenum is a strategic non-renewable mineral resources, its excellent properties, are widely used in iron and steel, chemical, military, electronics, computer, bio-medicine, agriculture and other fields. Molybdenum is an element with little distribution in nature, and the average content in the earth's crust is about 0.001. At present, there are more than 30 known molybdenum minerals, of which molybdenite is the most widely distributed and is the most important molybdenum mineral in the industry. According to relevant statistics [2], 99% of the world's molybdenum production is obtained from Yixuan molybdenum ore. With the development of science and technology, the demand for molybdenum is increasing, the reserves of molybdenum resources are drastically reduced, and the shortage of molybdenum resources has become an indisputable fact. Therefore, summarizing the domestic difficult selection of molybdenum resources and the progress of mineral processing technology , advancing the progress of mineral processing technology, and making better use of this part of the resources have certain practical significance for supporting the development of China's molybdenum and related industries.

First, the types and nature of complex refractory molybdenum ore in China There are a large number of various refractory molybdenum ores in the world. The treatment of such refractory molybdenum ore by traditional flotation method is not low. It is difficult to select a higher grade molybdenum concentrate product, or both. Low product quality and low resource utilization are two common problems that need to be solved. In addition, in China, refractory molybdenum ore also has a wide range of problems in dealing with such high energy consumption and environmental pollution. According to relevant statistics [3], the main refractory molybdenum ore in China is: high oxidation rate molybdenum ore, talc -containing molybdenum or talc-containing copper- molybdenum ore, carbonaceous, carbonaceous shale and organic molybdenum carbon molybdenum ores or metals, or fine-grained dip superfine molybdenum ores, complex structure and molybdenum ores. Most of these refractory molybdenum ores contain more than 0.08 molybdenum, which exceeds the industrial grade of molybdenum. Individual molybdenum ore contains more than 0.1 molybdenum, and is also associated with valuable metals such as lead , gold and silver . It has certain development value and comprehensive utilization value.

Second, China's difficult selection of molybdenum ore resources and its progress in mineral processing technology

(I) Progress of talc-type molybdenum resources and progress in mineral processing technology

Talc type molybdenum ore refers to molybdenite ore containing a certain amount of talc. Because talc and molybdenite are very similar in floatability, mineralists say talc and molybdenite are “equivalent floatable minerals”, and it is difficult to achieve them as a modern beneficiation technique. The talc-containing molybdenum ore is very common. For example, the famous large-scale ferromolybdenum symbiotic deposit in Shangfanggou, Heilongjiang Jixi Molybdenum Mine, Henan Sanmenxia Night Changping Molybdenum Mine, and a molybdenum mine in Hubei all contain more talc. Research on mineral processing technology of talc-type molybdenum ore, Zhengzhou Institute of Mineral Resources Comprehensive Utilization of Chinese Academy of Sciences [4] conducted a groundbreaking study on the Shangfanggou molybdenum deposit in Luanchuan, using magnetic separation-grading-mud sand sorting-new medicament for ore The process of inhibiting non-metallic gangue minerals with good buoyancy and other non-metallic gangue minerals was completed in 2000. The technical indicators are: molybdenum concentrate grade >45%, recovery rate >80%, comprehensive recovery of iron concentrate Grade > 64%, recovery rate 76%. He Chunming et al [5] discussed the beneficiation process of high talc-type ferromolybdenum ore in Shangfanggou mining area, and formulated “rough grinding-magnetic separation-magnetic separation tailings de-mud-molybdenum rough selection-fine grinding-molybdenum selection”. "The principle process, using CF-3, CF-4, CF-5 three drugs mixed drugs to inhibit talc, achieved an ideal index. On the basis of the pilot test, the Zhengzhou Institute of Minerals Comprehensive Utilization of the Chinese Academy of Geological Sciences [6] conducted an expansion test on the Shangfanggou talc-type molybdenum ore in 2007, and finally obtained a recovery rate by using a special agent for inhibiting talc. %, a good indicator of 45.12% of molybdenum concentrate grade. Dong Yuzhen [7] for a talc-type molybdenum ore, by using a better selective FT agent, preferential flotation talc and other easy-floating gangue minerals, followed by molybdenum, molybdenum coarse concentrate re-grinding and 8 times selected molybdenum The mine obtained an index of 45.54% molybdenum grade and 82.29% molybdenum recovery rate.

(II) Progress of high oxidation rate molybdenum resources and progress of mineral processing technology

High-oxidation molybdenum ore refers to the local oxidation of the upper part of the molybdenum deposit after wind erosion, rain, and sunshine in a long geological period, and molybdenum ore partially or mostly oxidized to molybdenum oxide or molybdate. Molybdenum oxide is naturally hydrophilic, a hydrophobic is extremely low, crystal is incomplete, and it is mostly fine-grained, which is very difficult to select. Many molybdenum deposits have hundreds of meters in the upper part and 10m in different degrees. Molybdenum oxide is a refractory molybdenum mineral because it is a natural hydrophobic mineral. Another reason is that there are many types of molybdenum oxide. Unlike molybdenite, the surface physical and chemical properties of various molybdenum oxide minerals are also different. In addition, most molybdenum oxide minerals have fine particle size and low floatability.

There are many molybdenum oxide resources in China. The Yunnan-porphyry molybdenum deposit contains molybdenum oxide with molybdenum content greater than 1%. The ore is yellow-brown and the oxidation rate is over 90%, which is very difficult to select. There are many molybdenum ore molybdenum ore in the southern part of Hunan Province, and the ore is yellow earthy. There is a large amount of "loess" on the bed of Luonan porphyry molybdenum deposit in Shaanxi, which is called "high loess" and is actually a molybdenum oxide belt. The "loess" is almost 90% of molybdenum oxide ore. The reserves are huge and need to be researched and developed. The Mo content is between 0.03% and 0.04%, which is the future treasure house of molybdenum. West Henan is an important molybdenum ore district in China, mainly molybdenum ore, but there are also quartz vein type molybdenum oxide and molybdenum sulfide mixed minerals. In some places, the molybdenum oxidation rate is as high as 80%. In addition, in the Mengbaotou area of ​​China, some large-scale molybdenum deposits have been discovered in recent years, and some places have been put into operation, but the ore dressing indicators have not been ideal. The ore is identified by rock ore, which makes the ore dressing index less than ideal. The main reason is the presence of a large amount of oxidized ore. Regarding the selection of high-oxidation molybdenum ore, there has been no breakthrough in domestic mineral processing technology. Zhengzhou Institute of Chinese Academy of Geological Mineral Utilization [9] water glass as sludge dispersants, coal oil as sulfide ore flotation collector, the modified sodium silicate gangue inhibitor, RT capture molybdenum oxide ore The preferred flotation sulfide ore re-floating oxidized ore can obtain 46.41% of molybdenum sulfide concentrate and 27.65% of molybdenum oxide concentrate from Mo0.34% ore. The total recovery of molybdenum is 78.01%. index.

Jiang Yuren [10] and other targets for a difficult refractory molybdenum ore in Shaanxi with high oxidation rate and serious muddying. A flotation process with a coarse and two sweeps was used. Kerosene was used as a collector and pine oil as a foaming agent to obtain 7.93% molybdenum. The molybdenum coarse concentrate has a recovery rate of 82.76%. Then, an appropriate amount of water glass is added as a dispersing agent in the ball mill to obtain a coarse concentrate containing 5.31% of molybdenum by sodium flotation-induced flotation, and the recovery rate is 85.53%. The former has a 2.77% increase in recovery. Zhengzhou Institute of Mineral Resources Comprehensive Utilization, Chinese Academy of Geological Sciences [11] for a gold-containing molybdenum oxide ore with sodium carbonate as a pH adjuster, the dosage is 1500g / t; modified water glass is an inhibitor of gangue minerals, the amount is 800g / t; RJT is a collector, the amount is 350g / t. The process of rough selection, three sweeps, three selections, and one fine sweep was used to carry out the oxidized ore flotation test, and finally the selection index of 23.5% of molybdenum oxide concentrate and 42.83% of operation recovery rate was obtained. Liu Xuesheng et al [12] conducted a pilot study on collectors and modifiers for a highly oxidized molybdenum oxide ore in a large undeveloped molybdenum deposit in China. It was found that the QY collector was combined with a modifier to initially solve the molybdenum oxide mineral. For the flotation problem, the preliminary closed-circuit test results are: good indicators of molybdenum ore grade 2.89%, concentrate grade 25.27%, and recovery rate 76.53%.

(III) Status of carbon-bearing nickel- molybdenum ore resources and progress in mineral processing technology

The nickel-molybdenum deposit is a symbiotic ore that is mainly nickel-molybdenum and contains vanadium , uranium and various rare metals of valuable value. The molybdenum mineral is mainly composed of molybdenum-molybdenum ore (MoS2), which is an amorphous molybdenum sulfide mineral, which is transformed into a hexagonal molybdenum ore by heating. Nickel minerals are nickel disulfide, nickel ore, and arsenic nickel.

Molybdenum ore is a unique polymetallic complex mineral resource in China, mainly distributed in Zunyi, Guizhou, Zhangjiajie, Hunan, Duchang, Hubei, Yunnan and Fuyang, Zhejiang. South China is a sedimentary nickel-molybdenum-vanadium polymetallic deposit and the main metallogenic belt of precious metal mineralization.

The mineral containing valuable metals in addition to substandard Ni, Mo, also rich in platinum group metals and rare earth metals, is a complex multi-metal ore, wherein Zunyi Nickel and molybdenum northwest Hunan its resources are large resources, The high grades of nickel, molybdenum and precious metals have attracted great attention. Since this ore contains a large amount of graphite , although nickel and molybdenum exist in the form of sulfides, they coexist with pyrite with ultrafine particle size, and it is impossible to separate nickel and molybdenum by a conventional beneficiation method. If this ore is used alone as molybdenum ore, it will cause nickel loss. If it is used as a nickel ore, high molybdenum content will seriously affect the existing nickel metallurgy process. Due to the particularity of mineral morphology, the comprehensive recovery and beneficiation effect of molybdenum-nickel mineral resources is not satisfactory, and smelting currently stays in the process of electric furnace smelting ferromolybdenum, roasting-leaching, high temperature oxygen pressure leaching, normal temperature wet leaching, etc. It is limited to minerals with a molybdenum grade of more than 2%, and it causes serious pollution to the environment. In response to the refractory ore, many units have carried out a lot of research work and achieved certain results.

Pei Guanhua et al. studied the problem of extracting molybdenum from refractory nickel-molybdenum ore and proposed a method of first desulfurizing nickel-molybdenum ore at 600 °C, then leaching it with alkali and active oxygen, and passing the comparison test. The optimum process conditions were determined: sodium hydroxide 30% (or sodium carbonate 50%), leaching solution solid ratio of 3:1, temperature 90-100 ° C, reaction time 3 h. The test results show that the process is obviously superior to the traditional extraction method, and the use of sulfur dioxide flue gas released during the roasting process to obtain sodium metabisulfite can greatly alleviate the environmental pollution caused by sulfur dioxide emissions.

Under the optimum process conditions, the leaching rate of molybdenum is close to 100%. In order to solve the problem of comprehensive recovery of high-carbon molybdenum-nickel ore, Chen Daixiong and others, based on the nature of ore, have been experimentally researched to decarbonize first, to obtain a part of the concentrate containing higher molybdenum, and then add activator TSN-1 for molybdenum-nickel. Mixed flotation to obtain a molybdenum-nickel mixed concentrate. The decarburization operation not only excluded the influence of carbon on the molybdenum-nickel flotation in the latter stage, but also laid a good foundation for the latter stage flotation. The process is relatively simple, no need to re-select decarburization, and has greater innovation. Chen Liyun et al. conducted mineral ore leaching and leaching studies. The results showed that when the mineral beneficiation obtained 30% Mo concentrate, the recovery rate was less than 50%, after acid roasting, acid leaching or alkali leaching, followed by solvent extraction or ion exchange. The molybdate product obtained by the molybdate and acid leaching-extraction method contains only about 35% Mo, and the recovery rate is only 65%. The alkali leaching-ion exchange method can obtain the molybdate product with good quality, but in the leaching residue. The Mo content is still as high as 1.70% to 1.5%. Li Qinggang et al [18] used the process of ore crushing ball milling → sodium hypochlorite decomposition → ion exchange → purification → crystallization → drying, and carried out industrialization test. The results show that the ammonium molybdate product obtained by the full wet process has reached the national standard MSA21 standard. The metal recovery rate of the whole process is over 85%, and the processing cost of tons of ammonium molybdate products is less than 50,000 yuan. The main advantages of this process are friendly environment, high metal recovery rate, simple process and good product quality.

(IV) Other refractory molybdenum ore resources and progress in mineral processing technology

Other refractory molybdenum resources are mainly polymetallic symbiotic ore with molybdenum as the main, such as copper-molybdenum symbiotic ore [19], uranium-molybdenum symbiotic ore [20]. Regarding the beneficiation research of molybdenum polymetallic symbiotic ore, the recovery technology of molybdenum has been very mature. At present, the main problem is that the associated metals are not well integrated.

III. Conclusion Through a large number of mineral processing technology research and research, in recent years, China's complex refractory molybdenum ore beneficiation technology has made gratifying progress, but due to the complex nature of China's molybdenum ore and the low level of comprehensive mineral processing technology, it is difficult for China. The utilization rate of molybdenum ore resources is extremely low, and even some minerals are not effectively utilized. Therefore, the following aspects should be strengthened in the future.

1. For talc-type molybdenum ore, research and development of talc inhibitors should be strengthened in the future.

2. The national science and technology department should cooperate with relevant scientific research institutes to carry out scientific and technological research on molybdenum resources with certain reserves and certain development prospects.

3. Strengthen the process mineralogy research of refractory molybdenum ore, thoroughly investigate the reasons for the difficulty of selection, and provide strong technical support for the selection.

4. For some difficult-to-select molybdenum mines, strengthen the joint technology of metallurgy and research and explore the bioleaching process.

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