Tungsten minerals can be divided into scheelite and wolframite. In general, scheelite is much more floatable than wolframite.

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%.