(I) Beneficiation processing method 1. Beneficiation method of mineral processing bentonite is generally divided into dry method and wet method. Most of China's current mines use dry process beneficiation.
Dry beneficiation is generally used to treat bentonite with better ore quality. The method is to dry the raw ore, dry it naturally, dry it with dry mash and dry the oven, then crush it with a manual or jaw crusher, then grind it into 100, 150, 200 mesh with Raymond mill and other roller mills. Level products are sold.
Wet beneficiation is generally used to treat low grade bentonite with a smectite content of 30% to 80%. The method is to pulverize the ore to a particle size of less than 50 mm, add water to make a suspension, and then classify in a hydraulic separator, and the fine grade concentrate obtained is concentrated in a precipitator, dried in a dryer, and then powdered. Grinding, products that are suitable for drilling mud grades.
2. Modification
Bentonite modification includes artificial sodiumation of calcium-based bentonite, preparation of activated clay and organic bentonite.
The artificial sodiumation of calcium-based bentonite is also divided into dry and wet methods. The dry method is to add a sodium-containing reagent (generally sodium carbonate) to the calcium-based soil, and convert it into sodium-based bentonite by mixing and extrusion, and Na-Ca displacement reaction. The wet method is to stir and disperse with sufficient water when the reagent is mixed with the soil.
The preparation of acidic (active) clay is also available in both dry and wet processes. The wet method is to add hydrochloric acid (or sulfuric acid), water and a dispersing agent before mixing and extruding into a strip, and to stir and disperse well; in the dry method, it is only necessary to add hydrochloric acid (or sulfuric acid), and then fully stir.
The organic bentonite is obtained by adding sodium bentonite to an ethylene glycol solution of an organic amine salt, and stirring and reacting at a high speed.
1. Bentonite beneficiation process
The dry dressing process of bentonite is generally: raw ore → hand selection → preliminary drying → initial crushing → drying → grinding → classification → packaging.
The wet dressing process of bentonite is generally: raw ore → pulping → sand removal → classification → dehydration → drying → grinding → packaging.
2. Bentonite modification process
Bentonite modification process is generally: calcium-based bentonite ore → crushing → mixed extrusion → drying → milling → air classification → cyclone filtration → sodium bentonite products.
(II) Process flow and equipment The process of artificial sodiumation of calcium-based bentonite is generally: calcium-based soil ore → crushing → adding sodium carbonate (wet method also needs to add water) → mixed extrusion → rotary furnace drying → milling → air classification → Sodium-based soil products.
The processing procedure of active (acidic) clay is generally: bentonite→crushing→addition of hydrochloric acid or sulfuric acid (we need to add water and dispersant in wet process)→full agitation→mixing extrusion→rotary furnace drying→heating air grinding→air classification→storage.
The general process of organic bentonite processing is: raw ore → crushing → dispersion → modification (sodiumification) → purification → ammonium salt coverage → rinsing → dehydration → drying → crushing → packaging.
The most commonly used equipment for bentonite processing is Raymond Mill, which has specifications of 3R, 4R, 5R, etc. In addition, in the modification of bentonite, mixing and extrusion equipment such as a wheel mill and a screw extruder are often used.
(III) Dressing and processing practice 1. Montenegro bentonite mine Liaoning Heishan bentonite mine is one of the large open pit mines currently being exploited in China. The mine has an annual production capacity of 100,000 tons. The ore is directly sent to the drying field after being mined by the mine, and the ore water is reduced from an average of 31% to 15%. The semi-dry bentonite after drying is dried or directly ground before grinding. The fineness of grinding is 100, 150 and 200 mesh respectively. After drying and drying to reduce the moisture to less than 12%, the packaging is shipped. The product is mainly used for casting, pellets and drilling mud. The price of the 200 mesh product is 54.4ml/15g and the wet compressive strength is 36.28kPa. The process of artificial sodiumation of the calcium-based bentonite is shown in Figure 1. Sodium carbonate solution is used for sodiumation at a concentration of 3% to 4%. The swelling ratio of bentonite after sodiumation is increased by 15 to 20 times, and the adhesion, fire resistance and the like are greatly improved, the wet strength is 49.03 kPa, the colloidal price is 100 ml/15 g, the pulping rate is 10 m 3 /t, and the pH is 8.5.
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