1. The ore dressing method for beneficiation and purification of talc is as follows:
1) Flotation Because the natural floatability of talc is good, the hydrocarbon oil collector can be floated. Commonly used collectors are kerosene and flotation oil as a foaming agent. The foam produced by methyl isobutyl methoxide (MIBC) is brittle and easy to obtain high quality concentrate.
The talc flotation process is relatively simple, and only one rough selection, one sweep, and two to four selections can be used to obtain the final concentrate.
2) Hand player selection is based on the slipperiness of talc and gangue minerals. Talc has good slipperiness, the higher the grade, the better the slipperiness, and it is easy to identify by hand. Most of the talc mines in China use hand-selected high-grade talc blocks.
3) In addition to talc, the electrostatic ore dressing talc ore also contains minerals such as magnesite, magnetite, magnetic pyrite, tremolite, and the inlaid grain size is about 0.5 mm. In the electrostatic field, talc has a negative charge, magnesite has a positive charge, and magnetite and magnetic iron ore are good conductors, so it is easy to separate the above minerals in an electric field.
4) Magnetically selected talc concentrates must have a certain degree of fineness in addition to a certain degree of fineness. Due to the presence of dyed iron minerals in the ore, sometimes the above method is not sufficient, and magnetic separation is required to remove the iron mineral. Wet magnetic separation can reduce the iron content of talc concentrate from 4% to 5% to less than 1%.
5) Photoelectric detection Photoelectric detection is a method of sorting using the different optical properties of talc and impurity minerals. Photoelectric sorters include preparation mechanisms (mines, feeders, belt conveyors), radiation sources and detectors (sensors), electronic control loops, and actuators. In addition, the use of talc to emit white fluorescence under ultraviolet light can be used to pick out pure talc using a photoelectric sorter. Generally, the labor Turks 621 type optical sorting machine is used. For example, the tussah company of the United States has used this method to enrich the lean ore with a talc content of 30% into a rich ore with a talc content of 69%, and finally grind to 200 mesh for flotation. , get 99% cosmetic grade talc.
6) Selective crushing and sieving The difference in selective crushing and shape between talc and gangue minerals can be separated by impact crushing and alternating rectangular sieves and square sieves to separate most of the associated quartz and More than half of the carbonate minerals.
2, fine grinding and ultra-fine grinding talc is ultimately applied in the powder state, therefore, fine grinding and ultra-fine grinding is the processing technology necessary for talc.
Talc has a Mohs hardness of 1, which is naturally breakable and grindable. Fine grinding of talc, the domestic general use of various types of Raymond mill (ie, suspension roller mill), mainly produces 200 mesh and 325 mesh products, but if you set up fine grading equipment, you can also produce 500-1250 mesh products. Ultra-fine talcum powder is one of the most used ultra-fine powder products in the world, widely used in paper, plastic, rubber, paints, cosmetics, ceramics and so on. At present, the processing of ultrafine talcum powder mainly adopts a dry process.
Although wet pulverization has been studied, it is rarely used in industry. Dry production equipment mainly includes high-speed mechanical impact mills, jet mills, centrifugal self-grinding mills, rotary mills, and vibration mills, mixer mills and tower mills. In addition to the jet mill, in order to meet the user's requirements for particle size distribution, other grading equipment generally needs to be equipped with subdivision equipment. The commonly used fine grading equipment is various turbine air centrifugal classifiers, such as MS type, MSS type, ATP. Type, LHB type, etc.
The principle of airflow pulverization of talc is as follows: talc-coarse-drying-medium-fine grinding (Raymond mill)--superfine pulverization (airflow mill)--cyclone aggregate-packaging production process is roughly talc Firstly, the feeder is sent to the hammer crusher for crushing; the crushed material is dried by the bucket elevator and the vibrating feeder into the vertical dryer; the dried material is broken by the hammer crusher and then enters the mine. The finely ground talc powder is finely ground into a jet mill for ultrafine pulverization. The final product fineness can reach 500-5000 mesh (d97=30-5um).
The jet mills used in the industry include disc-type jet mills, fluidized bed-to-jet jet mills, circulating tubular jet mills, and the like. The high-speed mechanical impact superfine pulverization process of talc is as follows: talc-crushing (hammer crusher)--high-speed mechanical impact type superfine pulverizer-turbine fine classifier-cyclone aggregate-packaging is generally talc After the block is broken to 8 mm, it is directly fed into a mechanical impact type ultrafine pulverizer, and the pulverized product is classified by a turbine type fine classifier and then collected by a cyclone collector. The graded fine-grained product can be returned to the mill or used as a separate product. The centrifugal self-grinding of the talc and the ultrafine grinding process of the rotary mill are generally similar to the high-speed mechanical impact superfine grinding process.
3. Surface-modified talc powder is widely used as a reinforcing filler for polymer-based composite materials such as polypropylene and nylon.
Surface modification can effectively improve the affinity of talc powder with polymer and the dispersion state of talc filler in polymer matrix, thereby improving the physical and mechanical properties of the composite. The surface modifier used for surface modification of talc mainly includes various surfactants, paraffin, titanate and zirconium aluminate coupling agents, silane coupling agents, phosphate esters and the like. The modification mainly adopts a dry modification process. The modification machine mainly includes a continuous type and a fluidization modification machine, a continuous vortex type powder surface modification machine (SLG type), a high-speed heating mixing kneader and the like.
4. Calcination The Guangfeng area of ​​Jiangxi Province in China contains abundant black talc resources.
The reason is that some talc mines contain more organic carbon. In order to exploit these black talc resources, calcination is a necessary process. The calcination temperature is generally 600-1200 ° C. In this temperature range, the higher the temperature, the higher the whiteness of the talc after calcination, and the whiteness of calcination is up to 90%. At present, most of the calcining equipments use a shuttle kiln, a tunnel kiln and a rotary kiln.
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