Lump Bentonite for Building Material

1 Foundry industry

Foundry bentonite is the largest user of bentonite, with an annual consumption of 1.1 million tons.

Bentonite is mainly used in clay-bonded sand for casting, because bentonite has the characteristics of strong cohesion, high plasticity, good release film, excellent air permeability, and stable physical and chemical properties under high temperature and wet conditions. Clay-bonded sand is used as a molding material to produce castings, which is a long-established process. Today, with the vigorous development of various chemically-bonded sands, clay green sand is still the most important molding material. It is so large that no other modeling material can match it. Modern high-pressure molding, injection molding, air-blast molding, static pressure molding and non-shock vacuum pressure molding and other new processes are also based on the use of clay wet molding sand, which has a strong ability to adapt to molding conditions. . Foundry bentonite mainly includes sodium bentonite and calcium sodium bentonite. Sodium bentonite is processed from natural sodium bentonite or artificial sodium bentonite. It is popular in the foundry industry for its good reusability and high wet compressive strength. . Due to its good plasticity, it can prevent the phenomenon of sand inclusion, scarring, falling blocks, and sand mold collapse. In addition, it has strong formability and high cavity strength, which is convenient for casting wet or dry molds in the metal industry. It is the first choice for precision castings. Sand Binder. Calcium-sodium bentonite is processed from natural base calcium-sodium bentonite, which is a commonly used molding sand binder for light castings. It is popular with users for its practicality and ease of casting sand cleaning. Compared with other binders, bentonite has an important feature that it has a certain heat resistance. As long as the heating temperature is not too high, the bentonite from which free water has been removed can still restore its stickiness as long as water is added. The binding ability of bentonite can only be exhibited after adding water. The loss of binding ability of bentonite is also related to its dehydration. So far, it is believed that there are three forms of water in bentonite: one is free water, that is, the water adsorbed by bentonite particles. When heated to above 100 °C, the free water can be removed, and the bentonite with free water is removed. It is not affected; the two kinds of water are firmly bound water. When heated for a long time at 110 °C, bentonite can completely remove free water, but will not remove firmly bound water. The bentonite that has completely removed free water will continue to lose weight when heated at a higher temperature (such as 200°C, 300°C), indicating that there is still water loss. After the bentonite is heated and dehydrated in this way, as long as water is added, the bonding ability can be completely restored; the three types of water are lattice water, which is also called structural water. Lattice water can only be partially or completely removed at relatively high temperatures. After the lattice water of the swelling water is removed, it loses its binding ability and becomes dead clay. Different bentonites have different temperatures at which they lose their binding ability. It is proved by the differential thermal analysis experiment: Generally speaking, the failure temperature of natural sodium bentonite is 638℃, and that of calcium bentonite is 316℃. Artificially activated sodium bentonite has different failure temperatures due to different activation conditions, but it is lower than natural sodium bentonite.

2 Drilling mud

Bentonite for drilling mud is the second largest user of bentonite, with an annual consumption of 700,000 tons.

Bentonite is a clay mineral with montmorillonite as the main component. It has strong water absorption and can absorb water equivalent to 8 times its own volume, expands 10 to 30 times in volume, and is suspended and gelled in aqueous solution. . When drilling oil and gas, mud is used to cool the drill bit, remove debris, protect the well wall and balance the ground pressure. Bentonite has good dispersibility and large slurry output, so it is an ideal material for manufacturing drilling mud. For bentonite used as drilling mud, the most important technical requirements are suspension properties, wet screen analysis and moisture content.

Bentonite plays an important role in drilling, making it a very large amount. It is understood that, on average, about 8 tons of bentonite are used for each well mined.

3 Iron ore pellets 

Bentonite for iron ore pellets is the third largest user of bentonite, with an annual consumption of 450,000 tons.

Bentonite for iron ore pelletizing is one of the important accessories in the modern metallurgical industry. After the concentrate iron powder is mixed with an appropriate amount of bentonite and water, it is rolled into a ball shape in a pelletizer, and then dried, preheated, baked and sintered into a high-strength The pellets are then smelted.

4 Activated clay and granular clay

Activated clay is a chemical product processed from bentonite. It has many functions of activated carbon, and the price is much cheaper than that of activated carbon. Therefore, it is widely used in various mineral oils in the petroleum industry, animal and vegetable oils in the oil industry, solid and liquid paraffin, fatty acids, waste oil regeneration, ethanol and benzene and other decolorization and purification. It can also be used for clarification of wine and juice, purification of sugar juice in sugar industry, catalyst carrier in chemical industry, additives for powder pesticides, etc.

There are about 40 manufacturers of activated clay in my country, with an annual output of about 420,000 tons. The largest production facility has a capacity of 50,000 t/a. The production areas of activated clay are mainly concentrated in Northeast China, North China, East China and other regions, and the output accounts for more than 70% of the whole country. At present, the demand for activated clay in my country is about 650,000 t/a, and about 40,000 tons are imported every year.

Granular clay is made of activated clay as the main raw material, which is scientifically formulated and chemically treated. High adsorption capacity, widely used in the purification of aromatic hydrocarbons in the petrochemical industry, the refining of aviation kerosene, and the refining of lubricating oil, base oil, diesel oil, etc. Nitride and other impurities. At present, domestic granular clay is mainly used to replace American TONSIL granular clay for olefin removal in aromatic hydrocarbon complexes, aviation kerosene and solvent oil refining, etc. . Granular clay is sometimes called oil filter silica gel. The use of oil filter silica gel can remove acid and sludge, biocolloids, and leaching of insulating materials. It can remove moisture, impurities and chromatographic analysis of hydrocarbon gases. It can be used for sewage treatment and toxic Gas filtration and catalytic cracking in petrochemical oil industry.

5 Desiccant

Bentonite desiccant has the functions of adsorption activity, static dehumidification and odor removal. It is widely used in products that cannot be sealed by oil and gas phase, such as optical instruments, electronic products, medical care, food packaging, and dry air sealing of military and civilian products. Compared with silica gel, it has the advantages of low price, fast adsorption speed and low preparation cost. Compared with other types of desiccants currently on the market, it not only has fast adsorption speed, high adsorption capacity, but also has the characteristics of non-toxic, odorless, non-contact corrosive, and non-environmental pollution. It is especially used in food packaging and does not harm the human body.

The export volume of bentonite desiccant is large.

6 Cat litter (granulated bentonite)

Cat litter (granular bentonite) is made of high-quality natural bentonite, which is dried and refined at high temperature. It has the characteristics of white and beautiful color, strong adsorption force, small specific gravity, durable and suitable for household pet cleaning and sanitation.

The export volume of cat litter (granulated bentonite) is large.

7 Sewage treatment

Using bentonite as animal gasket material to treat wastewater, odor bentonite can make animal manure easy to disperse and clean. Since the sewage and odor produced by captive animal farms, slaughterhouses, and aquatic products processing plants are harmful to the environment, bentonite can be sprinkled in these places to recover high-efficiency fertilizers.

Bentonite can be used as a clarifying agent for turbid water, a waterproofing agent for polluted water, and a sewage treatment agent. Bentonite was used to treat printing and dyeing wastewater, gas washing wastewater, monosodium glutamate factory and other wastewater and waste, and the removal rate was 99.5%.

Scattering bentonite in the upstream of the reservoir can flocculate the unclean substances in the reservoir and sink to the bottom of the reservoir for biological purification.

8 Construction Engineering

Using the lubricity, bonding and sealing, thickening and cementitious properties of bentonite to make mud, it is used for lining anti-seepage in various soil operations, such as partition wall construction, grouting, caisson, piling, land anti-seepage, Cement and concrete construction additives, solid water conservancy transportation, sewage treatment and tunnel shield lubrication, etc.

The river channel is paved with bentonite impermeable layer, which can lead the limited water to the distance. The bentonite waterproof layer can be directly laid with natural sodium-based bentonite powder, or it can be mixed and compacted with bentonite and local soil, or the bentonite can be sandwiched between two layers of fabrics to form a waterproof (permeable) blanket (board), which can quickly build a water storage tank and storage tank. Water kiln, aqueduct.

Bentonite can be used as waterproof material, such as corrugated cardboard with bentonite waterproof board, two layers of non-woven waterproof felt with bentonite in the middle, and one layer of non-woven and one layer of plastic board with bentonite double waterproof board. This material has been used in subway, It is widely used in underground engineering at the bottom of dams and landfills. Bentonite has a high degree of water tightness and the function of self-repair and recovery. It is waterproof and compact (sodium bentonite forms a diaphragm under water pressure, and when the thickness is about 5mm, it is equivalent to 100 times the compactness of 30cm thick clay), self-retaining water. Good performance (when sodium bentonite reacts with water, it has l3-l6 times the expansion force, so it can repair cracks on the concrete surface within 2mm) and has permanent waterproof performance (sodium bentonite will not age or corrode) and other characteristics. Bentonite is harmless to human body and has excellent environmental protection properties. Construction is simple. No need to heat and paste, not affected by air temperature. At the same time, the construction period is short, and compared with other waterproof materials, the construction is relatively soft and simple. Use only nails and washers. No special inspection is required after construction, and it is easy to repair if waterproof defects are found.

9 Food

Used as food additive and emulsifier in food, it can be used as calcium supplement and diet food.

Bentonite clay can clarify fruit juice and sugar juice.

Bentonite can soften hard water.

Bentonite is used for clarification of wine by fixing nitrogen without precipitation, reducing the formation of acetaldehyde and hydrogen sulfide, and eliminating all foreign odors.

10 Paint

Bentonite is used as a multifunctional white coating in the paper industry. It also acts as an anti-pitch adsorbent in pulpers, as a retainer in machinery, and as a rheology modifier in pulp.

Bentonite can also produce coatings. It is used as viscosity modifier and white mineral filler in coatings, and can partially or completely replace titanium dioxide; it can also partially replace polyvinyl alcohol, and it can also be used as a binder for non-woven fabrics and gypsum board particles.

Bentonite can modify the oxidized starch binder, which not only increases the solid content of the glue, reduces the water content, but also plugs and fills the gaps of paper fibers (especially straw pulp paper), reduces the water permeability, and improves the viscosity. The initial tack and drying speed of the mixture. Experiments show that bentonite has good effect and low price, and is an ideal quick-drying agent.