A. Scheelite flotation (1) Flotation method of scheelite. The molecular formula of scheelite is CaWO4. Because the molecular formula contains calcium, it is prone to chemical adsorption and chemical reaction to fatty acids. Common collectors are vegetable oleic acid and 731 oxidized paraffin soap. Vegetable oil oleic acid Zhongshan Cangzi oleic acid has excellent selectivity and collection. 731 oxidized paraffin soap has better selectivity, but poor collection power. ZN633, a new agent of scheelite produced in recent years, has the characteristics of low temperature resistance, selectivity and good collection performance, which greatly provides grade and recovery rate. Since scheelite often coexists with various calcium and magnesium phosphates, sulfates, carbonates, and fluorides, their floatability is similar, and it is often difficult to select qualified concentrates. To enhance the selectivity of the process, the following methods can be used: 1) Use sodium sulfide, cyanide, chromate, etc. to inhibit its associated sulfide minerals (if there are many sulfide minerals, you must first float separately); use water glass, tannin, sodium polymetaphosphate, chromate, etc. to inhibit its gangue Mineral: Use water glass or sodium carbonate to adjust the PH value of the pulp to 9.5 ~ 10, and 11 ~ 12 when selecting. 2) Lime-flotation method. The main points are: adjust the slurry with lime (about 0.5kg / t), then add sodium carbonate (about 0.15kg / t) and water glass (about 2.2kg / t), and finally use oleic acid and naphthenic acid (the two The ratio is 1: 1) collection. The characteristic of this method is that Ca2 + in the slurry is first adsorbed on the surface of the gangue minerals. When sodium carbonate is added, the Ca2 + adsorbed on the surface of the gangue becomes a CaCO3 film that is more easily suppressed. It can greatly improve the grade of concentrate. 3) A large amount of water glass heating selection method (ie Petrov method) is used. To add low-grade coarse concentrate, add 40 ~ 90kg / t water glass, heat up to 60 ~ 90 and cook for a while, stir and dehydrate (substantially remove the excess agent on the surface of the gangue), then adjust the pulp, then select 4 ~ 8 times to get higher grade concentrate. If the concentrate still contains more barite, the alkyl sulfate or sulfonate can be used for reverse flotation of the barite at a pH value equal to or less than 1.5 ~ 3. When the concentrate contains phosphorous, it can be leached with hydrochloric acid Concentrates are selected to dissolve the phosphate minerals. After solid-liquid separation and washing, the phosphorus content in the scheelite concentrate can be qualified. In the scheelite deposit, there are often some symbiotic minerals (such as tin, molybdenum, etc.), these symbiotic minerals will enter the scheelite concentrate during the re-election process, affecting the quality of the concentrate, therefore, in the flotation of scheelite There is also the problem of separation of tungsten tin and tungsten molybdenum. The separation of scheelite and cassiterite can be carried out by electric separation or flotation. During flotation separation, scheelite is captured with fatty acids, and cassiterite is suppressed with water glass. When scheelite contains aluminum, because molybdenum has good floatability, molybdenum ore can be floated first, and then scheelite.
(2) Examples of scheelite flotation. The main metal minerals in a tungsten ore are natural gold, antimony ore, scheelite, and golden iron ore, followed by pyrite, wolframite, sphalerite and so on. The main gangue minerals are quartz, followed by calcite, apatite, pyrophyllite and so on. The scheelite is generally produced in the quartz veins in coarse grains and irregular blocks, sometimes in thin layers and sheets in the antimony ore, and a small amount in thin lines in the surrounding rocks. The plant uses a combined heavy-float process to produce scheelite concentrate in both gravity and flotation. The scheelite concentrate produced by the re-election is of high quality and close to the premium grade. The scheelite concentrate produced by the flotation is of slightly lower quality and is often mixed with the re- election product before leaving the factory. The feed to the flotation operation is re-election (shaker) tailings. The original ore is ground by the second stage. The first section is coarsely ground to less than 0.8 mm, and coarse-grained white tungsten, antimony and gold are selected with a shaker. Shaker tailings are finely ground to 80% -0.074mm, mixed with antimony and gold by adding yellow medicine, black medicine, lead nitrate and copper sulfate, and the tailings after antimony and gold are floated to scheelite and oleic acid As a collector, sodium carbonate adjusts the PH of the slurry to about 9, and water glass is used as an inhibitor of silicate. Coarse beneficiation of scheelite produces a crude concentrate containing about 5% WO3. Because a large amount of calcium-containing minerals such as calcite and apatite also float together, beneficiation of scheelite is required. Select the thick slurry heating method, that is, first concentrate the scheelite coarse concentrate to 50% solids, then add a large amount of water glass (90kg / t coarse concentrate), heat it to about 90 with steam, stir for one Hours, then dilute the pulp to 20%, keep the pulp temperature between 26 ~ 30 , and select at a pH of 9 ~ 10. At this time, calcium-containing minerals such as calcite are suppressed, and apatite still floats together with scheelite, so the end of the process has the operation of acid leaching phosphorus. The concentrate obtained by flotation contains WO350% ~ 55%, after acid leaching it contains WO365% ~ 70%, and the recovery rate is over 85%.
B. Wolframite flotation Common black tungsten minerals are tungsten manganese iron (Fe, Mn) WO4, tungsten iron ore (FeWO4) and tungsten manganese ore (MnWO4). They are homogeneous minerals. The floatability sequence of these three minerals is: Tungsten manganese> Tungsten manganese ore> Tungsten iron ore
Collectors commonly used in flotation wolframite are oleic acid, sulfosuccinamide, benzuric acid and phosphonic acid. Salicylhydroxamic acid is also a promising collector for futonite. Oleic acid has a strong collection power but poor selectivity. The PH value of the wolframite flotation with oleic acid is similar to that of scheelite, and sodium carbonate is used as the adjusting agent. The flotation of wolframite with phenylarsinic acid and phosphonic acid is carried out in acidic medium, and the regulator used is sulfuric acid or hydrochloric acid. Commonly used lead nitrate as activator. The gangue inhibitors of flotation wolframite are: sodium fluorosilicate, water glass, a mixture of water glass and aluminum sulfate (6: 1), dichromate, sulfuric acid and hydrofluoric acid. However, the wolframite itself can be inhibited by a large amount of oxalic acid, sodium fluorosilicate (above 4kg / t) and water glass, etc., so the amount of related inhibitors must be strictly controlled. Black tungsten ore flotation reagent-ZN802 Purpose: flotation and recovery of fine tungsten ore slime: good collection, selectivity and low temperature resistance. It has wide applicability to flotation and recovery of fine tungsten ore slime and is a national patented technology product. It can replace the traditional beneficiation agents 731 and 733, overcoming the shortcoming that the oxidized paraffin soap cannot withstand low temperature. A fine tungsten ore dressing plant processes finely selected fine mud, and its feed particle size is 36% less than 0.074mm. The metal minerals are wolframite, pyrite, limonite, sphalerite, and bismuthite. The grade of tungsten is 8% ~ 10%, and the gangue is garnet and quartz. Flotation with a mixture of phenylarsinic acid and oxidized paraffin soap, after a rough two sweep, the indicators are as follows: Original grade WO36% ~ 8%; concentrate grade WO340% ~ 47%; recovery rate WO378% ~ 82%.
At present, the grade of raw tungsten ore in the world is decreasing year by year. There are less and less easy-to-mining wolframite, while refractory scheelite and wolframite-scheelite intergrowth ore gradually occupy the main position. Therefore, Xinhai Mining strengthens the research on tungsten extraction process, and customizes the ideal tungsten extraction equipment according to the different types of tungsten ore, strives to improve the tungsten extraction efficiency and reduce the production costs.
Xinhai uses the sodium sulfide, cyanide and chromate to inhibit the associated sulfide minerals, and adopts the sodium silicate, tannin, sodium polyphosphate, chromate to inhibit the gangue minerals. Then, using the sodium silicate or sodium carbonate to adjust the pH value of the pulp to 9.5-10, and 11-12 for cleaning stage.
Xinhai adopts sodium silicate heating method, which means adding a certain amount of sodium silicate to low-grade coarse concentrate, heating up, cooking, stirring, dehydration and slurry mixing, then concentrating repeatedly. Finally, the high-grade tungsten concentrate can be obtained.
That is, the jigging gross sand is produced when the qualified ore is sent to multi-stage jigging after the vibrating screen. The coarse-grained jig tailings are sent to grinding mill for re-grinding, and the fine-grained jig tailings enter into multi-stage shaking table after the classifier, then the shaking table gross sand is produced. The shaking table tailings are sent to the tailings pond, and the middlings are returned for regrinding and re-separating, and the gross sand of jig and shaking table is sent to concentrating stage.
Concentrating: Xinhai adopts flotation-gravity separation combined process or flotation-gravity separation-magnetic separation combined process, and recovers the associated elements in the concentrating stage.
Through the coarse and fine-grained table flotation (flotation -shaking table combined method) and flotation to remove the sulphide ore, the sulphide ore of table flotation and flotation merges into the sulfide ore flotation separation. And the wolframite after table flotation and flotation becomes the wolframite concentrate by the gravity separation process. If there are scheelite and cassiterite in the wolframite concentrate, gravity separation-flotation or gravity separation-flotation-magnetic separation combined process can be adopted to separate wolframite concentrate, scheelite concentrate and tin concentrate.
Fine sludge treatment: Xinhai usually carries out desulfurization first, and then adopts gravity separation, flotation, magnetic separation, electric separation or combined process to recycle the tungsten ore according to the properties of fine sludge, and utilize the associated metal minerals at the same time.
For the extraction of tungsten from wolframite-scheelite intergrowth ore, especially the fine-grained wolframite-scheelite intergrowth polymetallic ore, Xinhai usually adopts the bulk flotation process.
Bulk flotation of sulfide ore - bulk flotation of wolframite and scheelite - heating and separation of scheelite - strong magnetic separation of scheelite tailings - gravity separation of wolframite;
Before: The original plant adopted crushing pre-separation-gravity separation-concentrating process, which resulted in the loss of a large amount of fine-grained tungsten minerals, high mineral processing cost and poor mineral processing indexes.
After: After making the careful research on the ore properties and processing technology, Xinhai decided to optimize the wolframite process, add fine slime processing technology, and finally get the better mineral processing indexes.
After the modification, the recovery of fine-grained wolframite was strengthened obviously, and the influence of fine slime on the wolframite separation was reduced, which obviously improved the recovery indexes and the economic benefit of the plant.
Xinhai has make class B design qualification, and set up mine design institute and mineral processing research institute. More than 200 professionals provide the technical support service for 70 kinds of ore.
Depending on its professional mineral processing EPC+M+O service, Xinhai has got the EU certification, and ISO9001:2015 quality management system certification, who is classified as the assured brand with advanced products and standard quality!
Xinhai has multiple patents technologies, more than 500 mineral processing plants spread among China, Southeast Asia, South America, Africa, Iran, Russia, Mongolia, North Korea and other places, and Xinhai has established multiple overseas offices around the world.
Scheelite (CaWO4) and Wolframite ((Fe,Mn)WO4) are the principal minerals of tungsten, but other important minerals include ferberite (FeWO4) and huebnerite (MnWO4) will also respond to froth flotation. The high specific gravity of these minerals makes many of these ores amenable to gravity concentration methods, however, the fine dissemination of mineral in gangue for some ores may require finer grinding and recovery of mineral by flotation at finer sizes.
Flotation of Wolframite (Including ferferite and huebnerite) Wolframite basedtungstenexhibits very similar flotation properties to that of cassiterite; hence it is floated in an acid medium using sulphosuccinimates (Cyanamid S3903 or Allied Colloids CA 540) or styrene phosphonic acid (SPA), and is floated as cassiterite.
New advances have been made in the application of phosphonic and arsonic acids in the flotation of wolframite slimes. The collecting effectiveness of these two collectors is ouch better than that of carboxylic collectors. Flotation results of wolframite slime roughing products using phosphonic or arsonic acid collectors are recognized to be more satisfactory, and this flotation system is adopted extensively in Chinese wolframite mills. For example, the high-intensity magnetic separator product grade is 6.9% WO3 and arsonic acid flotation gave a final concentrate grade of 50.94% WO3 with 95% recovery. Table 1 shows that flotation recovery is more effective in the size range of 60 to 0 m.
The flowsheet consists of three sections: centrifugal separation of low-grade slimes, wolframite flotation of gravity concentrates, and magnetic separation of flotation concentrates to upgrade concentrates. Before centrifugal separation, it is necessary to undertake bulk sulfide flotation. The adoption of the centrifugal separation/flotation/magnetic separation process has led to technical and economic improvements. The recovery of tungsten slimes was raised from 46.76% (conventional tabling) to 61.48%, and the grade was improved from 51.85% to 61.32% WO3. The advantages of this process are that the mixture of primary and secondary slimes is treated without sorting, a high-grade concentrate being obtained without further desliming; additional tungsten recovery comes from tailings by the centrifugal separators; there is a high recovery of tungsten by flotation and effective removal of impurities by magnetic separation; and lower investment and production costs are involved.
The flowsheet is composed of four parts: scaling and low-intensity magnetic separator for removing wood chips and tramp iron, high-intensity wet magnetic separation for removing gangue minerals, sulfide flotation, and wolframite flotation. Performance data of industrial-scale tests and full production are shown in Table 5.
Tailings of the shaking table are fed to the centrifugal separator, and concentrates of the centrifugal separator concentrator are sent to the belt sluice for upgrading. The process yields tungsten concentrate grades of 10-16% WO3 and 62% recovery.
The B-M separator is a high-capacity preconcentrator, and the crossbelt is an upgrading concentrator, both of which utilise the same separation mechanism. The most-common applications of the flowsheet fall into two categories:
Addition to existing plant to treat final tailings or a specific product such as table tailings, flotation tailings, cyclone overflow, etc. Retreatment of materials in the tailing dump. The metallurgical data for the recovery of tungsten from plant tailings are indicated in Table 6.
Tungsten ore processing, that is separation and beneficiation of tungsten minerals from tungsten bearing ores. Tungsten concentrates are sent to smelters to refine the metals tungsten, tungsten carbide, tungsten alloys and tungsten compounds, while tungsten middlings is chemically treated to produce synthetic scheelite, ammonium paratungstate, tungsten powder and tungsten carbide. Minerals and Resources There are more than 30 kinds of tungsten minerals in nature, but tungsten minerals of industrial significance are mainly scheelite and wolframite, followed by Calcium tungsten molybdenum ore (CaMo)wo, and copper-tungsten (Cuwo). Wolframite can be divided into Ferberite, wolframite and huebnerite according to the content of FeO and MnO. Wolframite has weak magnetism, which increases with the increase of iron content.
Tungsten distribution The worlds tungsten resources are mainly concentrated in the countries bordering Asia and the Pacific. Chinas tungsten reserves and production ranks the World First, mainly in wolframite. Other major tungsten producing countries are the former Soviet Union, Canada, South Korea, Bolivia and so on, dominated by scheelite.
How is tungsten extracted from its ore? The main beneficiation methods for tungsten ores are physical methods such as pre-concentration, gravity concentration, flotation and magnetic separation; as for the refractory middling ore and low-grade concentrate, prefer to chemical concentration way.
Wolframite property: tungsten from wolframite ore mostly in quartz vein type, high dilution rate, low grade, coarse particle size, high density, low hardness, easy sliming and deep color. Wolframite mineral processing method mainly in gravity separation, and includes four parts: pre-selection, gravity separation, concentration and recovery.
According to the paragenetic relationship between scheelite and different types of gangue ores, scheelite ores can be divided into different types, and the beneficiation methods for different types of scheelite ores are also different. For example, scheelite-quartz (or silicate) type can be used in combination with gravity separation and flotation according to the particle size distribution, while scheelite-calcite-fluorite-barite type can be recovered by flotation.
The separation methods of scheelite are different with different disseminated grain size. For coarse-grained scheelite, generally uses a gravity separation method, which has the advantages of lower cost, less environmental pollution and higher recovery ratio. For fine size scheelite, the separation uses the flotation separation method.
Scheelite flotation is carried out in alkaline medium, adjust slurry PH value in 9 ~ 10 by the sodium carbonate, sodium hydroxide. Common inhibitors are sodium silicate, tannin, various phosphates. Collectors have sodium oleate, tar oil and oxidized paraffin, etc. Scheelite has good floatability, but it is often associated with fluorite, calcite, apatite, barite and gangue minerals containing calcium and barium, those have similar floatability, increase the separation difficulty. In order to improve the flotation selectivity of scheelite and calcareous gangue minerals, multi-metal salts, such as iron sulfate, are often used in combination with sodium silicate to improve the flotation effect of scheelite.
For the single scheelite and wolframite with simple composition, the separation process is relatively simple. For the paragenetic ore of wolframite and scheelite, especially the paragenetic polymetallic ore of fine-grained wolframite and scheelite, tungsten is usually recovered by a mixed flotation process. There is two main tungsten ore dressing plant design:
(1) Mixed flotation of sulfide ore mixed flotation of wolframite-heated scheelite concentrate strong magnetic separation of Scheelite tailings gravity separation of Wolframite; (2) Mixed flotation of sulfide ores strong magnetic separation of wolframite scheelite flotation-wolframite flotation.
Case Tungsten ore processing plant JXSC focuses on mining equipment manufacturing, established in 1985has quite of experience of mining machine configuration and layout design & optimization among various minerals, gold, silver, diamond, copper, titanium, tungsten, coltan, chrome, and so on.
Mining Equipment Manufacturers, Our Main Products: Gold Trommel, Gold Wash Plant, Dense Media Separation System, CIP, CIL, Ball Mill, Trommel Scrubber, Shaker Table, Jig Concentrator, Spiral Separator, Slurry Pump, Trommel Screen.
The results of investigations into increasing the contrast of process properties of calcite and scheelite due to the combined application of water glass with salts such as sulfates of aluminum, zinc, iron, magnesium; mixtures of water glass and calcium chloride; sodium carboxymethyl cellulose (CMC); combinations of sodium oleate with low-polar compounds (neonol and fatty iso-alcohols); and data on the ultrasonic treatment of the liquid phase and oleate are described. The lowest recovery of calcite during the flotation of a monomineral calcite fraction in the Hallimond tube is attained when jointly using salts of iron(II) and water glass (3(4) : 1). The joint application of water glass and CaCl2 during the flotation of the low-grade scheelite ore with a high carbonate modulus using tap water lowers the calcite flotability. When using recycled water, adding calcium chloride to water glass leads to a certain increase in the yield of the rough concentrate (from 13.8 to 14.1%) with a significant decrease in the recovery of WO3 into the final selection concentrate of scheelite (from 72.7 to 53.3%) and worsens the concentrate quality. The replacement of water glass by CMC showed no satisfactory results. The ultrasonic treatment of the pulp, liquid phase, and collector leads to a certain increase in calcite flotation activity, possibly due to an increase in the liquid phase temperature and in the fraction of the ionic form of oleate. The use of neonols in the reagent flotation mode of the scheelite-containing ore with a high carbonate modulus does not confirm a decrease in the flotation activity of calcite formed when studying monomineral calcite fractions, in contrast with fatty iso-alcohols, which make it possible to fabricate the higher quality concentrates in the selection cycle when compared with one oleate.
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Sn was first separated from wolframitescheelite ore by reduction melting process.99% of tin was volatilized in the form of SnS in reduction melting process.(Fe, Mn) WO4 was converted to CaWO4 and Ca2(Fe, Mn)WO6 with the increase of CaSO4.CaWO4 and Ca2(Fe, Mn)WO6 were digested completely by sulphuric-phosphoric acid.
The separation and extration of tin and tungsten from wolframite scheelite mixed ore with high tin content is urgently needed given the increasingly exhaustion of the high-grade tungsten ore. However, current tungsten hydrometallurgy technologies suffer from considerably drawbacks, such as low recovery of tin, high consumption of chemicals, and large sodium salt waste water discharge. In this study, a novel reduction melting pretreatment method was used for the thorough separation of tin in the purification process and to improve the recovery of tin and tungsten. In this process, tin was first separated from tungsten and recovered in the form of SnS. Approximately 99% of tin was volatilized under the optimized conditions of the [WO3]/[CaSO4]/[C] molar ratio of 1:2:4 after blowing nitrogen at a flow rate of 3L/min for 15min, and the tin content in the reduction melting products was less than 0.05%. Meanwhile, wolframite was converted to scheelite and ferric calcium tungstate that then were easily digested by the mixed sulphuric-phosphoric acid solution, and the leaching ratio of tungsten reached 99%. The leaching residue of calcium sulfate was reused as the sulfurizing reagent in the reduction melting process. The efficient separation and extraction of tin and tungsten of this technology indicated its potential for industrial application.