Tungsten ore beneficiation (2)

Table 7 Soviet advanced tungsten concentrate quality standards

Table 8 Foreign quality tungsten concentrate quality reference materials

6. Main mineral processing methods and recovery of by-products
Most tungsten deposits are low grade ore. The ore grade of tungsten ore in China was about 0.5% WO ₃ in the 1950s, and some reached 0.7% WO ₃ , and dropped to 0.25-0.33% WO ₃ after the 1970s. The foreign tungsten ore grades are up to 1% WO ₃ , such as the Canton tungsten mine in Canada. Different types of ore are sorted by different beneficiation methods and processes. The main beneficiation methods of the black tungsten ore and scheelite are described as follows:
1. Beneficiation of Hematite (1) Pre-enrichment Most black tungsten mines have a high depletion rate of mining, often above 80%. It is extremely important to pre-dispose coarse and poor waste rock before re-election. China's black tungsten ore dressing plant, according to the boundary between the ore-bearing gangue and the surrounding rock is clear, the color is clear, easy to distinguish, the ore is washed and classified, and a large amount of waste rock can be discarded by artificial hand selection. In particular, the narrow-scale backhand selection of coarse-grained ore can improve the picking efficiency. The hand-selected waste rock rate is generally 50%, the high is 70%, and the low is about 35%. The selected waste rock grade is 0.015~0.04%. The proportion of tailings selected by WO3 is low, and the recovery rate of the operation is 96.5~99%.
Heavy media beneficiation 70 years has invested in eastern Hunan, and Tong Yang Hongling three tungsten mineral processing plant, with pyrite as a weighting agent, were selected in the cyclone and turbo separator carve, have achieved good technical and economic index. For example, the combination of hand selection and heavy medium beneficiation in Xiangdong Tungsten Mine increased the selection rate of waste rock from 43% of the original single hand to 57%, and the cost of mineral processing decreased by 5-11%. The selection rate of waste rock in Yangtang Concentrator increased from 40% to 53%, and the cost of mineral processing decreased by 8.1%. The selection rate of waste rock for vortex sorter in Hongling Concentrator is 50~59%, and the cost of ore dressing is reduced by 2.3%. Later, due to the depletion of mine resources or the loss of associated metals, the heavy medium beneficiation of several tungsten mines was suspended.
Photoelectric picking is sorted according to the color difference between the ore-bearing gangue and surrounding rock. Several models of photoelectric picking machines have been developed by Zhangzhou Nonferrous Metallurgy Research Institute, Dajishan Tungsten Mine and Yaogangxian Tungsten Mine. The mine can process 20~40 mm ore, which can replace some artificial hand selection.
Some black tungsten ore mining plants abroad also attach great importance to pre-enrichment. For example, the Panasqueira tungsten mine in Portugal, 80% of the ore is pre-enriched by heavy medium, and the equipment used is a single 500 mm heavy medium. cyclone, ferrosilicon as medium, separation density from 2.72 to 2.75 g / cm ^3, the sorting ore grain size of 0.5 to 2.5 mm accounted for dropped to 95% of the light product ore, mineral rate equivalent to the original 76% of the waste rock grade is 0.025%. The Hemetaon tungsten plant in the UK is selected using the new Dyna Whirpoll Process. The ore has a particle size of 0.5 to 9 mm and is made of ferrosilicon and magnetite. 80 to 90% of waste rock. The Mt. Carbine tungsten mine in Australia is the most effective example of using the photoelectric picker. The mine uses three M-16 pickers to divide the broken ore into 16~40, 40~80 and The 80~160mm three-stage is sorted by photoelectric picker, which separates the dark gray surrounding rock from the quartz containing black tungsten and white tungsten. The ore grade after sorting is enriched from 0.09% WO ₃ to 0.9% WO ₃ , recycling The rate is 90%, the disc disposal rate is about 91%, and the three pickers process 300 tons of ore per hour.
(2) Gravity beneficiation Hematite is mainly based on gravity ore dressing. Common wolframite ore minerals in their density (g / cm ³⁾ can be discharged Shu following series: 7.1 to 7.5 wolframite, cassiterite 7, 6 arsenopyrite, scheelite 5.4 ~ 6.1 pyrite 5, Hui 4.8 molybdenum, 4.6 pyrrhotite, 4,5 barite, brass mine 4.2, 4 sphalerite, siderite 3.9, 3.9 to 4.2 garnet, fluorite 3.1 ~ 3.1 2.8 mica, feldspar 2.54 ~2.8, calcite 2.5~2.8. The black tungsten ore has a high density and can be effectively separated from many minerals with a density of less than 3.5 to 4 by re-election. Especially in the quartz vein black tungsten deposit (mostly such tungsten ore in China), the black tungsten ore has large crystal grains, and it is more suitable to use re-election and early recovery in the case of coarse particles.
In the re-election operation, the jig and the shaker are common equipment. When selecting the black and tungsten-embedded black tungsten ore, the jig plays a major role. Before the selection, the ore sieve is often divided into three levels ( 10~4.5, 4.5~2, 2~0 mm), graded into jig. In order to reduce the mud ratio of the wolframite, the jig is inserted into the jig in the grinding cycle, so that the tungsten mineral which has been dissociated from the monomer is recovered early. The tungsten concentrate selected by the jig generally accounts for more than 45% of the total recovery rate of the whole plant.
The shaker is suitable for sorting medium and fine-grained grades (2~0.03 mm) of ore. The advantage is that the enrichment ratio is very high. In order to obtain a good sorting effect, it is necessary to strictly classify the materials before being selected. The concentrator is often graded using a four to six room hydraulic classifier.
The spiral concentrator is a large and low-cost equipment. It is widely used to sort materials of 0.074 mm or slightly thicker. It is especially suitable for sorting poor materials, such as the Climax molybdenum mine in the United States. A large number of black tungsten ore containing low grade (0.03% WO ₃ ) was selected from the tailings of flotation molybdenum by a spiral concentrator, which was also popularized in the tungsten-selecting process of Shizhuyuan and Xingluo.
(3) Fine mud treatment Tungsten minerals are brittle and easy to produce mud. According to statistics, the yield of raw and secondary fine mud (-0.074 mm) in domestic black tungsten ore dressing plant accounts for about 10% of the original ore, and the content of WO ₃ The rate is higher than 14%, and the grade of the slime is generally higher than the original grade, which is a difficult material. [next]
The slime is mainly from the pre-selected washing water, the dewatering in the re-election process and the overflow of the classifier. The overflow water of each of the above operations must be collected and concentrated separately before being selected, and then separately processed. Commonly used re-election equipment includes groove shaker, spring shaker, centrifugal concentrator and belt chute. Among them, the centrifugal concentrator has a large processing capacity, a high recovery rate, and a treatment particle size lower limit of 10 micrometers, which is an efficient rough selection device. The re-election equipment for foreign clay selection is the Bartles-Mozley sorting machine and the Bartles cross-belt belt. The former is used for rough selection and the latter is used for selection and effective separation. The particle size is selected from 100 to 5 microns, and the combination of the two is used as a matching equipment for sorting fine mud.
Black tungsten flotation has been studied in China. Toluene acid, benzyl phthalic acid, Medialen, styrenephosphonic acid, alkyl hydroxamic acid, 8-hydroxyquinoxaline, etc. are black tungsten. An effective collector for flotation; lead nitrate or ferrous sulfate can be used as an activator for wolframite. In the sorting process, it is recommended to carry out new processes such as branch flow flotation, speed selection, and thick slurry aeration, which can save the floating medicine and improve the flotation effect.
In addition to conventional flotation, carrier flotation and the separation of dispersed quartz by means of hydrophobic agglomeration and pellet agglomeration of black tungsten fines, respectively, through precipitation and sieving, respectively, have obtained good results. It will provide a new way for beneficiation of black tungsten fine mud.
In terms of magnetic separation, the newly developed wet-type strong magnetic separator has been used to select black tungsten fine mud. Therefore, in the process of black tungsten fine mud production, there is a beneficiation process of centrifugal concentrator-flotation; wet strong magnetic separation-flotation and the like, so that the recovery rate of black tungsten fine mud is greatly improved, and the concentrate grade is improved. At the same time, the recovery rate increased from 45 to 59% to 60 to 73%.
(4) Concentrate re-enrichment and comprehensive recovery of by-products In addition to the black tungsten ore, some dense minerals such as cassiterite, scheelite and most sulfide minerals are accompanied by wolframite. Enter the coarse concentrate together. Therefore, it must be selected to improve the grade of tungsten concentrate, and comprehensively recover various by-products.
In order to obtain a commercial tungsten concentrate, the sulfide ore is usually separated from the re-selected coarse concentrate by wood floating and flotation. The floating energy of the wooden platform floats out the sulfide ore under coarse particles (2~3 mm), and the desulfurization rate is as high as 98%. In the process, some of the mixed gangue is removed again, which greatly improves the grade of tungsten concentrate. A highly efficient selection of equipment, in the tungsten selection operation, 70% of the coarse concentrate is selected by the wood platform. For some coarse concentrates with low tin content, qualified tungsten concentrates can be obtained only by Taifuge. The wooden table float is used for desulfurization and is also used for sorting white tungsten and cassiterite.
Magnetic separation can separate the black tungsten ore from the cassiterite and scheelite, and the electric selection is mainly used for the separation of scheelite and cassiterite. Of tungsten concentrates containing xenotime, which may be selected from the sorted electric xenotime, both to reduce the amount of phosphorous in the wolframite, it added comprehensive recovery of rare earth byproduct.
In addition, for certain minerals, the composition of the minerals is complicated. In order to meet the requirements of the products, in addition to the above-mentioned selection methods, it is sometimes supplemented by roasting and chemical beneficiation to facilitate purification and impurity removal, such as roasting sulfur, arsenic , chlorination roasting. In addition to tin; acid leaching phosphorus, calcium and so on.
The sulphide ore separated from the selection process is the main target of comprehensive recovery. After grinding and flotation, various by-products such as bismuth , molybdenum, copper, zinc and pyrite can be obtained, from the tail of magnetic separation and electrification. The by-products such as cassiterite, white tungsten and rare earth are recovered in the mine. In the hand-selection operation, beryl, crystal , lithium mica and rich ore of sulphide, molybdenum and copper sulfides can be sorted out. As for the comprehensive recovery from the re-election of tailings, only the Dalongshan Tungsten Plant of the Wutang Tungsten Mine will re-select the tailings for grinding molybdenum. The ore grade of the plant is 0.3~0.45% WO ₃ and 0.06~0.09%MO. After re-election, about 45% of the molybdenum entering the tungsten coarse concentrate is about 12% into the fine mud, and the grade is 0.18~0.25%. MO; the remaining 40% entered the re-election of tailings, the grade is about 0.16~0.08%MO. The latter is subjected to flotation and molybdenum after grinding, and the molybdenum concentrate grade is 48% MO, the operation recovery rate is 79%, accounting for 40% of the original mine molybdenum recovery rate, and the total recovery rate of the whole plant molybdenum is about 77%.
In summary, the principle process of China's black tungsten ore beneficiation is that the raw ore is coarsely crushed and then pre-enriched, and a large number of coarse waste rock is discarded; the qualified ore is crushed and sieved, and the third-stage jigging is used to strengthen the coarse grain early harvest; Tailing mine grinding classification, multi-stage shaker sorting, discarding tailings, re-election of medium-mineral re-election: concentrated concentration of fine mud, separate treatment; re-election of coarse fines by a variety of methods combined with selection, both to enhance tungsten Concentrate grade, and comprehensive recovery of by-products. The following picture shows the production process of China's black tungsten beneficiation principle.

Above picture Principle production process of China's black tungsten ore dressing plant [next]

2. Separation of scheelite ore dressing According to the characteristics of ore dyeing, it can be combined with re-election and flotation, or single flotation method. Individual scheelite ore dressing plants are also pre-enriched, such as The King Island scheelite ore plant selects 50% of waste rock from the ore by ultraviolet fluorescent picker. Its grade is lower than that of the tailings discharged from the concentrator. The recovery rate of scheelite is 90~96%. The picking capacity of the equipment is 35~40 tons/set.
The scheelite deposit is often accompanied by a variety of sulfide ore. Among them, molybdenum ore is especially common. In the process of beneficiation, the sulphide ore is generally floated and then the scheelite is floated. The flotation of scheelite is carried out in an alkaline medium. The pH of the slurry is adjusted to 9~10.5 with sodium carbonate and sodium hydroxide. The commonly used inhibitor is water glass (modulus 2.2~3), white bark juice. , tannins and various phosphates. Commonly used collectors are oleic acid, sodium oleate, tart oil, oxidized paraffin soap, etc. These collectors all have foaming properties, generally no additional foaming agent.
The scheelite has good floatability. In the ore, the flotation process is complicated by the presence of calcium-containing gangue minerals similar to their properties, such as calcite, fluorite, and apatite. In order to improve the selectivity of the flotation process, the addition of a polyvalent metal salt (such as ferrous sulfate) to the water glass can significantly improve the flotation effect of the scheelite.
Increasing the temperature of the slurry is also an important measure to improve the flotation of white tungsten. The Petrov method uses the slurry to heat up to 70-90 ° C, adding a large amount of water glass, so that the collector on the calcite surface is desorbed, scheelite Get selectively floating up.
A "lime method" flotation developed by Vazquez et al. of United Carbide Corporation of the United States can make scheelite have excellent selectivity in the presence of fluorite, contrary to the general theory. It is beneficial to add an appropriate amount of lime during the flotation process. It is considered that lime is added to the flotation system, and calcium ions are adsorbed on the surface of fluorite, calcite and quartz, which causes surface charge changes, from negative to positive, and white. Tungsten ore still maintains a negative charge. Then, when sodium carbonate is added to the slurry, the calcium carbonate precipitates on the surface of quartz, fluorite and calcite, while the scheelite is still negatively charged and the surface is not precipitated. After the addition of water glass, the inhibition of the other calculus is enhanced, thereby improving the selectivity of scheelite with calcite and fluorite flotation.
Shear flocculation flotation has been successful for the first time at the Yxioberg white tungsten concentrator in Sweden. This is a promising approach to improving the flotation of fine-grained scheelite. The method is to add an appropriate amount of flotation agent in the mixing tank before the white tungsten flotation, and control the pH and concentration of the slurry. Under strong stirring, the hydrophobic mineral particles collide with each other, and the water film is thinned to form hundreds of particles. The scheelite granules of the granules increase the effective size of the granules and are more likely to adhere to the bubbles and rise quickly. Recent semi-industrial tests conducted in Australia have shown that when the ore grade 0.83% WO ₃ scheelite ore is ground to 40-70%-15 microns, the recovery rate by conventional flotation is about 74% when the slurry is sheared. When flocculation is pretreated and then floated, the recovery rate is increased to 83%, the grade of coarse concentrate is also increased from 5% WO ₃ to 6% WO ₃ , and the value of multi-recovered tungsten is the cost of shear flocculation process. Times.
There are not many white tungsten flotation plants in China, accounting for about 5% of the processing capacity of tungsten processing plants. Floor finishes Baoshan scheelite flotation plant originally oleic acid as collector, with彼得洛夫法加temperature selection, after the collector in place of oleic acid to "731" oxidized paraffin soap, which is a sub-oil industry The production, the source is wide, the price is low, the pulp does not need to be heated during the flotation, and the high-quality selection index is obtained at room temperature, and it has been promoted and applied.
The search for a suitable pharmaceutical system and the implementation of normal temperature flotation are the development trend of scheelite flotation. Recently, in some studies of white tungsten ore dressing, “lime method” flotation was used, and oxidized paraffin soap was used as a collector at room temperature. Flotation yields high grade (>65% WO ₃ ) sulphur concentrate and high recovery. In order to ensure high recovery rate, in order to ensure high recovery rate, in many cases only low grade (15~30% 6WO ₃ ) concentrate is required, and then submitted to chemical beneficiation to produce synthetic white tungsten or ammonium paratungstate. Such products are economically advantageous, which is widely adopted abroad.

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