Barite is an important barium-containing mineral. It is widely used in petroleum, chemical industry, building materials and paint due to its high density, low hardness, stable chemical properties, non-toxicity, absorption of radioactive rays and other characteristics. an important strategic non-metallic mineral.
As a dominant mineral in my country, barite is mainly distributed in Guizhou, Hunan, Guangxi, Gansu and Shaanxi provinces. However, with the expansion of its application fields and the accelerated consumption of resources, the easy selection of high-grade barite ore has been decreasing day by day. At present, the proportion of barite commercial grade bonanza grades higher than 90% has declined. Salt and carbonate minerals coexist and can only be used after beneficiation.
The beneficiation methods of barite mainly include manual selection, gravity separation, magnetic separation and flotation. Among them, the beneficiation of barite ore associated with sulfide ore usually adopts flotation method or combined gravity separation and flotation process to recover barite after removing sulfide ore.
1. Manual Separation
For the high-grade barite ore, after coarse crushing, the massive barite is manually selected according to the color and gloss of the associated ore. The manual selection method is simple and convenient, low cost, and low dependence on equipment, but it has high requirements on ore and low production efficiency, which will cause great waste of resources.re the goals pursued in the future.
2. Gravity Separation
In actual production, most of them are low-grade barite ores, which are often closely associated with other metal ores and non-metallic ores in the ore-forming process, and manual selection often cannot meet industrial needs.
At present, barite ore (including its manual-separated tailings) is generally separated by gravity separation equipment such as jig concentrator and shaking table. In order to reduce the influence of particle size on separation, it is often classified according to particle size.
For barite compound ore with complex associated minerals, as well as barite ore with fine mineral inlaid particle size, low raw ore grade, and high concentrate grade, it is difficult to achieve the goal of gravity separation, and it needs to be further separated by flotation.
3. Magnetic Separation
When barite coexists with magnetic minerals such as siderite, magnetite and hematite, magnetic separation is an effective separation method, which can obtain high-grade concentrate products, which can be used as raw materials for the production of barium-based medicines. For the ferromagnetic minerals with finer grain size in barite, dry magnetic separators or wet high gradient magnetic separators are usually used to process them.
Due to the gradual dilution of barite ore resources, the ore composition is becoming more and more complex, and there are strict requirements on the grade and fineness of barite products in application, and methods such as gravity separation can no longer meet the demand. Flotation has gradually become the main method for sorting barite.
4. Flotation Separation
Flotation separation is not only an important way to deal with complex ores in traditional beneficiation methods, but also a commonly used method for the purification of salt minerals.
The interaction between the collector and the barite mineral has a great influence on the grade and recovery of the barite concentrate. At the same time, when flotation separates the associated minerals with similar floatability to barite, an effective inhibitor can increase the floatability difference between the two, which is also one of the keys to barite flotation separation. Therefore, in the flotation process of barite ore, both inhibitors and collectors play a very important role. Under conventional flotation conditions, the recovery rate of barite can reach more than 80%, and the collector used also has good foaming properties, so the research of activator and foaming agent are rarely involved in barite flotation.
In addition, flotation mainly occurs on the surface of barite minerals, and the quality of flotation is closely related to the flotation of barite, the surface electricity, the strength of chemical adsorption, and the pH value of the flotation environment.
5. Leaching and Purification
Leaching and purification is mainly used to remove colored impurities such as carbon, iron, manganese, vanadium and nickel in barite. Their existence affects the whiteness and application prospect of barite concentrate. The main methods to remove these impurities are: acid (alkali) leaching method, organic acid complex method, oxidation method, oxidation-reduction bleaching method, etc.
Acid (alkali) leaching treatment is the use of acid (alkali) to react with metals or metal oxides attached to the mineral surface to generate compounds soluble in water or dilute acid, and then filter and wash to separate the soluble matter, so as to achieve The purpose of removing impurities and purifying and improving the quality of minerals. Commonly used acid leaching agents are sulfuric acid, hydrochloric acid, nitric acid, oxalic acid and hydrofluoric acid, of which sulfuric acid is the most used; sodium hydroxide is often used in alkaline leaching.
The organic acid complexation method is to add organic acids such as EDTA, ascorbic acid, citric acid and oxalic acid in the process of removing iron impurities. Such acids can dissolve iron oxides and form complexes to achieve a good iron removal effect. .
The oxidation method is to use an oxidant to oxidize the iron minerals associated with the minerals into soluble iron salts, and at the same time oxidize the organic matter, making it into a colorless oxide that can be easily washed away. Commonly used oxidants are hydrogen peroxide and sodium hypochlorite, but the use cost of hydrogen peroxide is higher than that of sodium hypochlorite. The oxidation-reduction bleaching method is to first use the oxidant to react with the coloring substances in the barite, dissolve the coloring substances, and then add the reducing agent sodium hydrosulfite or sodium thiosulfate to reduce the impurity Fe3+ to Fe2+, which is filtered and washed to achieve purification and purification. whitening purpose.
6. Calcining and Purification
Calcining is an effective method for barite purification and whitening, which can directly remove the moisture in the ore and the impurities that can be oxidized and decomposed at high temperature. In industrial production, dyeing impurities such as Fe2O3, TiO2 and organic matter are distributed in barite crystals or fissures, making the ore gray, green, blue and black. Blue and gray, reducing the purity and whiteness of barite. Calcination can volatilize color-causing organic compounds, and the appropriate calcination temperature and time should be based on the premise of not destroying mineral crystals and maximizing the volatilization of organic compounds. In addition, adding chloride during calcination is beneficial to improve the whiteness of calcination.
On the whole, traditional physical beneficiation methods such as manual separation, gravity separation and magnetic separation have little effect on the development of some low-grade barite ores. In most cases, qualified concentrates must be obtained by combining flotation. The development and use of combined reagents in flotation is an important means to improve the flotation index of barite concentrate, and it is also the development trend of future reagent research. Traditional barite beneficiation products are only aimed at low value-added fields such as petrochemicals, such as weighting agents and barium-containing chemical products. Improving the fineness and whiteness of barium sulfate, developing high-purity barium salt and barium sulfate, and improving the added value of barite by physical and chemical methods are the goals pursued in the future.