Beneficiation, processing and environmental protection of barite

Mineral processing and processing

(1) The method of ore dressing of barite is hand-selected, re-elected, magnetically selected, and flotation

Hand selection: After the original ore is mined, the simple manual selection is a common dressing method used by many rural miners. Some mines, due to high geological quality and stable quality, can meet the requirements of foreign trade export after hand selection. For example, the Pancun Mine in Xiangzhou, Guangxi, selects the rich ore by hand selection, the particle size requirement is 30-150mm, BaSO4>95%, and generally can be greater than 92%. The hand selection method is simple and easy, and does not require any equipment, but the productivity is low and the resources are wasted.

Re-election: the original ore is washed and sieved, crushed, graded and de-sludged. After the jigging process, the concentrate with good quality can be obtained, and the product grade can reach over 88%. The concentrate of Hengnan barite mine after gravity dressing can reach 92%. The local people wash the mine with the soil method, and each person can get 100kg of concentrate per day. The crusher is generally a jaw crusher or an impact crusher, and the fine crusher is generally a pair of roller crushers. Select heavy medium drum sorting machine, cone classifier, jig sorter or shaker, screw machine, etc. The barite inlay has a particle size greater than 2 mm, and can usually be sorted by a heavy medium and jigging. The maximum particle size for heavy media sorting is 50mm, and the maximum particle size for wet and dry jigging is about 20mm. The inlay size is less than 2 mm and can be sorted by a shaker or a spiral classifier. Before the selection, a hydrocyclone should be used to remove the mud to improve the sorting effect.

Magnetic: used to select some of the iron-containing minerals such as siderite, barite raw material requirements for low iron barium-based drugs.

Flotation: China's barite ore has more ore and less ore, and more than 80% of the deposits with proven reserves are associated with other minerals. For the sorting of ore and re-selected tailings with very fine grain size, flotation must be used. There are positive flotation flotation and reverse flotation two types of reverse flotation is usually to remove the alkali metal sulfide.

As a common salt mineral, barite is divided into two types according to the adsorption form. One is an anionic collector such as fatty acid alkyl sulfate or alkyl sulfonate, which is chemically adsorbed. Adsorbed on the surface of barite minerals and separated from others; the other is the use of cationic amine collectors to float barite in a physically adsorbed form. Amine collectors are low in efficiency and sensitive to slime, so anionic collectors are preferred. Usually, NaOH is added to the ball mill to adjust the pH value to 8 to 10. The water glass is added to the slurry as a conditioning agent, and the oleic acid collector is used for flotation under the condition of a solid concentration of 40% to 50%. (2) Processing

1. Processing of high whiteness fine powder and ultrafine powder

The high whiteness finely pulverized barite powder is obtained by crushing, washing and whitening the barite ore. Holding the crystal structure of the mineral powder, widely used in coatings, rubber, plastics, paper, ceramics, etc., with a number of large and medium-coating plant which produce a variety of white powder paints instead of titanium, it is an excellent filler.

The Suizhou barite deposit is a sedimentary layered deposit. The results of mineral chemical analysis are: BaSO4 94.78%, acid soluble 2.1%, Si 0.72%, organic carbon 0.56%, Ca 0.43%, Fe 0.12%, Al 0.10%, Mg 0.17%.

After a few crushed ore to obtain a fine micron-sized raw material, the fired roaster 2.5h, clinker becomes removed alkalis, acid washed beating, sulfuric acid was added in the reaction vessel was washed with water, the aluminum powder (acid-soluble, Bleaching, stirring reaction at boiling temperature for 2.5 h, to obtain a bleaching material, washing off the soluble salts with water, pressing and drying (170 ° C) to become a finished product. The technical performance of the product meets the quality specifications of IS03262 barite b grade.

The chemical reaction process of acid reduction in the reactor is as follows:

Acid solution: dissolves impurities and colored elements with sulfuric acid.

[Fe2O3]+3H2SO4=Fe2(SO4)3+3H2O

[MnO]+H2SO4=MnSO4+H2O

[NiO]+H2SO4=NiSO4+H2O

Bleaching: Adding aluminum powder, generating hydrogen, reducing Fe2+ to bleach.

2Al+3H2SO4=Al2(SO4)3+3H2

Fe2(SO4)3+H2=2FeSO4+H2SO4

Among the above physical and chemical processing methods, bleaching treatment and ultrafine grinding are two key technologies. The bleaching treatment is carried out by calcination (removing carbon) and pickling (removing impurities and colored elements). Therefore, it is necessary to know the calcination temperature and time, the acid concentration, the rinsing time, the amount of the reducing agent added, and the number of times of addition and release, etc., which should be reasonably selected. Ultra-fine grinding should use high-efficiency grinding machine and reasonable selection of relevant parameters.

The South-East Geological Brigade of Sichuan Province applied ultra-fine barite powder technology to process high-quality barite from a certain area in Sichuan, and produced BaSO4≥98%, Fe2O3≤0.05%, ZBD whiteness≥90%, fineness 98%+≤2μm Ultra-fine powder, and applied in the production of paper, rubber, paint and plastic, can completely replace the precipitated barium sulfate, and the basic performance of the product is better, and the industrial application prospect is more extensive.

2. Production of strontium salt products

Barite as raw materials to produce products in addition to the barium salt lithopone (lithopone), the main barium carbonate, barium chloride, barium hydroxide, barium nitrate, barium sulfate, barium titanate, barium molybdate, and some fine Chemicals.

(1) Liede powder (zinc bismuth white) Liede powder is white powder with an average particle size of 0.3-0.5 μm. It is insoluble in water, and does not work with hydrogen sulfide and lye. It decomposes in acid solution to release hydrogen sulfide. It will change color after long-term sun exposure, but it can still restore the original color when placed in a dark place. In addition to the production of raw materials lithopone barite, there are zinc oxide, sulfate, powder coal, which is the main chemical reaction:

ZnO+H2SO4=ZnSO4+H2O

BaSO4+2C=BaS+2CO2

ZnSO4+BaS=ZnS·BaSO4

(2) The main raw materials of barium carbonate are barite, limestone and coal. The process flow is: barite, pulverized coal → pulverization → roasting → heating steam leaching → clarification → carbonization → adding soda ash, steam desulfurization washing → filtration → drying → packaging.

(3) Barium chloride barium chloride is a white shiny monoclinic crystal which loses water when heated to 113 ° C and becomes a white powder. Soluble in water, solubility increases with increasing temperature. The aqueous solution has a bitter and salty taste and is toxic to humans, animals and insects.

The main raw materials are barite, coal, hydrochloric acid or chlorine gas, calcium chloride and the like. The preparation method includes a hydrochloric acid method, a calcium chloride method, and a chlorination method. The hydrochloric acid method is obtained by reacting barite with pulverized coal after calcination and reacting with hydrochloric acid. The calcium chloride method is also firstly reduced and calcined, and then obtained by leaching, desulfurization and the like. The chlorination method is a method in which a ruthenium sulfide solution is reacted with chlorine gas to obtain a ruthenium chloride solution, which is then treated.

(4) Barium hydroxide barium hydroxide is a white tetragonal system, easily soluble in hot water, and the solution is strongly alkaline. Anhydrous cesium hydroxide is a glossy white amorphous powder that is toxic.

In industrial production, the caustic soda method is mainly used, that is, it is obtained by reacting caustic soda with barium chloride solution, and evaporating, crystallizing and separating. The main chemical reaction: BaCl2+2NaOH→Ba(OH)2+2NaCl

(5) Neodymium nitrate is a colorless or white cubic crystal, soluble in water and concentrated sulfuric acid. It decomposes at high temperature and decomposes into oxide when burned to emit green light and is toxic. It is mainly made of concentrated nitric acid and barium carbonate. It is also made of nitric acid (50%) and barium sulfide (such as Hengnan Chemical Pesticide Factory). The first grade product contains lanthanum nitrate ≥99.0%, and the second grade product ≥98.5%.

(6) Precipitated barium sulfate (barium sulfate) Barium sulfate is a white crystalline powder which is hardly soluble in water and is melted in fuming sulfuric acid and molten alkali. Easy and potassium permanganate, calcium carbonate, or alkali metal nitrate mixed crystal. Co-heating with carbon can be reduced to strontium sulfide.

The production method includes a barite refining method and a mirabilite- sulfurization method. The former is calcined with barite and coal powder, and then reacted with Na2SO4, and the latter is reacted with barium sulfide and thenardite, and subjected to Pressure Filtration and drying. Made separately. Environmental Protection Most of China's barite mines use open-pit mining. During the mining and washing process, many muddy waters are produced, polluting rivers, and polluting farmland during the rainy season. Since most of the mines are mined by township and village enterprises, and there are many mining points scattered, direct treatment is not easy to implement and it is difficult. Guangxi Petrochemical Department adopts centralized washing method and deducts environmental protection when paying mining producers' mine money. The treatment fee shall be used centrally and uniformly by the relevant departments of the county. According to the flow of water, the simple overflow dam in the downstream building will be discharged through the overflow port after clarification, which basically solves the problem of muddy water pollution.

The barite mine mined underground, the waste water discharged from the pit is tested, the water quality is non-toxic and harmless, and it is free to be discharged without special treatment. The three wastes discharged from the production of strontium salt contain toxic components, which are seriously polluted by the environment and must be treated.

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