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China is the world's most abundant tungsten resource. The reserves of tungsten ore, tungsten consumption, tungsten production and tungsten exports are among the highest in the world. China mainly consumes black tungsten ore. The smelting process is basically based on black tungsten ore. The black tungsten ore is dense, brittle, easy to be crushed and muddy. Black tungsten fine mud refers to materials of <74μm size. Due to the small particle size, the specific surface area of ​​each mineral increases, the difference in motion between particles becomes smaller, and the difficulty of sorting is greatly increased [1]. With the deepening of the mining of tungsten deposits, fine mud is continuously produced during the mining, transportation and beneficiation process. Even if the necessary measures are taken in each process, the generation of fine mud can not be avoided, and the loss of tungsten in the general selection of the plant is generally avoided. The rate is 20% [2]. Therefore, strengthening fine mud recovery and further researching more effective fine mud recovery processes and equipment have always been one of the important topics in tungsten ore beneficiation. The process technology for improving the recovery rate of tungsten fine mud, such as re-election, flotation, magnetic separation and fine metallurgy, has been explored [3].
1 Flotation process and pharmacy
Black tungsten ore is a high-density oxidized mineral, and black tungsten fine mud flotation has always been recognized as a problem at home and abroad. With the deepening, continuous improvement and perfect flotation production practice of the research on the theory of black tungsten fine mud flotation, the flotation method is gradually becoming the main means of recovery of black tungsten fine mud, and the treatment of black tungsten fine mud by flotation The more people pay attention to it [4]. The flotation method can greatly improve the recovery rate of black tungsten fine mud. The key is to use a reasonable process and effective flotation reagent.
1. 1 flotation process
Conventional flotation is difficult to recover efficiently with -10 μm of useful minerals or the recovery rate is very low. With the continuous improvement and improvement of the black tungsten fine mud flotation process, many promising sorting processes such as selective flocculation, carrier flotation, oil agglomeration and flotation have been introduced. Fine-grained technology is also an important branch of flotation technology. In addition, there are flotation column sorting processes [5].
(1) Selective flocculation process. The selective flocculation process [6] is to add a suitable adjusting agent (pH adjuster and gangue mineral dispersant) to the pulp in high-speed stirring, so that various minerals are dispersed, and then a selective flocculant is added. The target mineral is flocculated into a mass, and the gangue mineral is in a dispersed state. According to the ore property, various sorting methods (re-selection, magnetic separation, flotation, etc.) are used to separate the target mineral from the gangue mineral. The selective flocculation process is simple and easy to industrialize, and is a promising sorting process for recovering fine-grained useful minerals. The selective flocculation process needs to solve two problems: one is to study the selective flocculant of the target mineral; the other is to develop a regulator that overcomes the adverse effects of Ca2+ and Mg2+ and an effective gangue mineral dispersant. For the fine-grained black tungsten ore, Yang Jiuliu et al [6] used Na2CO3, (NaPO3)6 and FD flocculant to optimize the chemical system to mix the wolframite with quartz , fluorite , garnet and calcite. Separation of minerals (particle size is -10 μm). Lu Yiping et al [7] studied the flocculation behavior of polyacrylic acid (PAA) on fine-grained wolframite, and studied the flotation of fine-grained wolframite (-2μm) with sodium oleate as collector . A new floc flotation process--CPC floc flotation process was proposed. Under the condition of pH 6.8, the amount of oleic acid was 100 g/L, plus 1 mg/L PAA-5 and no addition. The flotation test of fine-grained wolframite with a particle size of -2 μm was compared. The recovery rate of tungsten is 17.83%, and the grade of concentrate WO3 is 2.94%. The granules of the granules are reduced from 0.25 mm to 4% in the original sample, and the maximum flotation particles are increased from 0.02 mm to 0. 088 mm. Under the above mixed conditions, a mixed sample of -0.22 mm grain of wolframite and quartz (1:1) was subjected to flocculation flotation, and the tungsten concentrate was obtained to contain WO368. 46%, and the tungsten recovery rate was 91. 31% of the sorting indicators, the sorting efficiency reached 69.10%, an increase of 17.83 percentage points than the conventional flotation.
(2) Carrier flotation process. The carrier flotation process utilizes the general flotation granular grade ore as a carrier, so that the fine particle cover is floated on the carrier, and the carrier can be used for the same mineral or heterogeneous mineral [6]. Qiu Guanzhou et al. [8] carried out carrier flotation with -0. 01 mm of different grades of wolframite to -0. 005 mm fraction of wolframite, the recovery rate increased from 40.5% to 70.38%. . Zhu Jianguang [9] carried out carrier flotation with -0. 005 mm fractional wolframite, and compared with conventional flotation under the same conditions, the supported carrier was +0. 01 mm of different grades of wolframite, The test results can increase the flotation rate of -0.65 mm fine-grained black tungsten ore and greatly improve the sorting effect of fine-grained wolframite. It has been shown that [10]: in a styrene phosphonic acid solution having a pH of 8, a fine-grained black tungsten ore of -0. 005 mm may be adhered to the coarse-grained black tungsten ore, and the coarse-grained black tungsten ore is -0.005 mm. The carrier of the black tungsten ore, and the interaction between the quartz of -0. 005 mm and the surface of the coarse-grained black tungsten ore is repelled, and the fine-grained quartz is difficult to adhere to the coarse-grained black tungsten ore, and it is difficult to be fine-grained with The occurrence of hetero-coagulation indicates that it is possible to separate the fine-grained black tungsten from quartz by the carrier flotation process with coarse-grained black tungsten ore as a carrier, which is of great significance for improving the fine-grained black tungsten flotation.
(3) Fine particle technology. The fine particle technology mainly includes oil agglomeration flotation process, hydrophobic agglomeration sorting and polymer flocculation, and the latter is not mature in the tungsten ore sorting. Oil agglomeration is under the bridge of neutral oil, and the mineral particles aggregate with each other to form a large and strong spherical group. The advantage of this process is that the fine-grained ore is also dehydrated at the same time, which simplifies the solid-liquid separation process, but it has a large dosage and high cost. Hydrophobic agglomeration is to first adjust the fine mineral and gangue minerals with a slurry, then use an effective surfactant to make the surface of the target mineral hydrophobic, and then add non-polar oil as a bridge medium. Under the action of the shearing force field, the target minerals with hydrophobic surface are aggregated, and then separated from the gangue mineral by a conventional process.
(4) Flotation column process. The microbubble flotation column is a flotation device capable of efficiently recovering fine particles, and has been widely used in fine particle size flotation and resource recycling. The microbubble flotation column uses microbubbles to enhance the recovery of fine-grain minerals to improve the recovery rate, and the use of the foaming area to reduce the gangue mineral inclusions to improve the concentrate grade. Huang Guangyao et al [11] developed a CMPT microbubble flotation column using microbubble technology in view of the failure of effective sorting of fine-grained grades in the white tungsten flotation tailings of Hunan Anhua Xiang'an Tungsten Company. The expert system is used to control the key parameters of the flotation column to ensure that the flotation column is in a good working state. Semi-industrial and industrial tests have shown that microbubble flotation columns can recover fine-grained white tungsten from flotation tailings. The optimum working parameters of the flotation column were obtained by a semi-industrial test, and the average concentrate grade and recovery were 24.52% and 43.41%, respectively, and the enrichment ratio was 35.03. The water analysis test showed that the recovery rates of 3~10μm, 10~19μm and 19~38μm were all above 65%.
Due to the mass effect and surface effect of the fine-grained minerals, the CMPT process is technically difficult, and the key is the efficient recovery of useful minerals in the fine-grained particles. The effective ways that can be used are mainly three kinds of adjustment, granulation and foaming, that is, finding efficient flotation reagents, selecting a reasonable process, and developing a flotation device for fine-grained particle flotation.
In addition to the above flotation process, there are two liquid sorting, ion flotation, etc. These flotation processes are the same as the above processes, and there are still many factors that need to be perfected. After the efforts of researchers, there will be more and more The black tungsten fine mud flotation process is applied to production.
1. 2 flotation agent
In the case of black tungsten fine mineral flotation, the most important agent, especially the selectivity of the collector should be the first problem to be solved. The ore dressing researcher has done a lot of research work and made a lot of progress.
(1) A new type of highly efficient chelation collector. For a long time, in order to improve the recovery rate of tungsten fine mud, researchers have carried out many studies on the pharmaceutical system to improve the flotation effect of black tungsten fine mud [12]. In recent years, the research on the flotation theory and flotation reagents of the wolframite has been particularly strengthened, and the chelation collector is still the focus of research on the fine-grain flotation agent of the black tungsten ore in China. The new oxonium chelating collector COBA has good collection performance for wolframite, but when COBA is used alone, the wolframite is basically not floating, and only when mixed with sodium oleate and 2# oil can it be used for its collection. performance. The single mineral flotation test of -75~+38μm black tungsten ore shows that the recovery rate of tungsten is only 90% when sodium oleate 8×10-5mol/L is used alone, and the amount of mixed collector of COBA and sodium oleate is used. When only 3×10-5mol/L and 2# oil 50mg/L (to improve the foaming effect), the recovery rate of tungsten can reach 90%, and when the amount of mixed collector is increased to 5×10- At 5mol/L, the recovery rate of tungsten can reach 99.1%, indicating that the use of COBA can greatly reduce the dosage of the agent, and COBA has good collection performance for the black tungsten ore fines [13]. The distribution ratio of WO3 in scheelite, wolframite and tungsten in a tungsten fine mud (70% -30μm) in Jiangxi is 45. 30%, 53. 01%, 1. 69%, modified by Na2CO3. Na2SiO3 and Pb(NO3)2 are used as adjusting agents, TA-4 is used as collector to rough-select black and white tungsten ore, and then heated and selected for separation. The foam is acid-leached to obtain scheelite concentrate, and the tailings are selected by heating. The black tungsten concentrate was obtained by shaking the bed. The test results show that the reasonable addition of Na2CO3 directly affects the sorting effect of black and white tungsten mixed flotation. The new tungsten-selecting collector TA-4 is the key to improve the tungsten sorting index. The selection of Chinese and Canadian NTA is beneficial to the separation of scheelite and wolframite. 0%, the recovery rate is 19.53%, the WO3 grade is 36.62%, the recovery rate is 19.53%, the WO3 grade is 59.55%, the recovery rate is 47.2%. The black gold concentrate, the tungsten concentrate has a WO3 average grade of 50.60%, and the total recovery is 66.74% [14].
Black tungsten fine mud dressing process
The research status of black tungsten fine mud beneficiation process is introduced, and the research status of new technologies such as flotation process and chemicals, improved centrifuge re-election process, high gradient strong magnetic separation process and metallurgical combination process are introduced. The outlook is forecasted.