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Mica classification
Mica mineral processing method
Mineral processing is an important prerequisite for improving the grade and quality of mica and achieving high-end applications to enhance the value of utilization. The mica beneficiation method is generally determined according to the mineral composition, occurrence state and embedding characteristics of the ore. The difference in physical and chemical properties between mica and other minerals in the ore is used to find a suitable beneficiation process for impurity removal and purification. The main beneficiation The methods include hand selection, friction dressing shape beneficiation, flotation and wind selection.
The flaky mica is usually hand-selected, friction-selected and shape-selected, and the crushed mica is separated from the gangue by air separation, hydrocyclone sorting or flotation.
As one of the most widely used beneficiation methods, flotation method also plays a very important role in the mica beneficiation. It mainly utilizes the difference of physical and chemical properties of mineral surface and is selectively rich in the solid-liquid-gas three-phase interface. One or several materials of interest are collected to achieve separation from the waste material. In addition to recycling mica as a useful mineral, mica is a common gangue mineral in many ores. Therefore, flotation is often used to remove mica gangue for effective sorting.
Mica flotation mechanism
1. Crystal structure and surface properties of mica
The mica mineral is a typical layered silicate mineral whose basic structure consists of a cation layer coordinated by an octahedron sandwiched between two identical (Si,Al)O4 tetrahedral monolayers. Some of the A13+ isomorphs replace the Si4+ in the siloxane tetrahedron, so the sandwich faces a charge that is compensated by the inter-layer cation. Rely on the interlayer alkali metal ions coordinated twelve interrelated, and ions having weak bond energy activity. Therefore, after dissociation of the mineral, the surface has a higher negative charge which is independent of pH in the aqueous solution, so that at a low pH, the cationic collector can also be covered in the negative charge region to make the mineral hydrophobic.
2. Research progress on the mechanism of action of flotation reagents and mica
The selection and use of flotation reagents is the key to obtain good flotation effect. The mechanism of action of pesticides and minerals can not only explain the flotation phenomenon from a theoretical point of view, but also guide the selection and synthesis of medicaments, and optimize the flotation process. helpful. There are not many researches on the mechanism of action of flotation reagents and mica at home and abroad. The research focuses on the mechanism of action of cationic collectors and mica. The research methods mainly include photoelectron spectroscopy, single mineral flotation test, adsorption measurement, potentiodynamic test and fluorescence test analysis. Along with the development of new detection technology and computer technology, atomic force microscopy (AFM) and molecular dynamics simulation (MD) have also been applied in this field, and some achievements have been made.
Since cationic collectors are widely used in mica flotation, there are relatively many studies on the mechanism of action of such collectors and mica, especially the mechanism of action of various primary and quaternary ammonium salts. Herder PC et al. reported the use of chemical analysis of photoelectron spectroscopy (ESCA) to quantify the adsorption of surfactants on the mica substrate. Nishimura S et al. used a plate flow potentiometer and atomic force microscopy (AFM) to study the adsorption of single-chain surfactant dodecyl-primary ammonium salts, secondary ammonium salts, tertiary ammonium salts and quaternary ammonium salts on the bottom-water interface of mica.
Liu et al. studied the hydrophobicity of the alkyl primary amine adsorbed on the surface of mica by surface contact angle measurement, atomic force microscopy (AFM) observation, density functional theory (DFT) and molecular dynamics simulation (MD). influences. The results show that the mica adsorbing octadecylamine is more hydrophobic than the methane adsorbing dodecylamine in the monolayer adsorption state, and the critical half micelle concentration (HMC) of octadecylamine is much lower. In dodecylamine, octadecylamine is more susceptible to multi-layer adsorption on the surface of mica, demonstrating that the longer the carbon chain of the alkyl primary amine, the stronger its ability to improve the hydrophobicity of the mica surface. The results of molecular dynamics simulation calculations also confirm this conclusion.
Yao Xu et al. used a PCFF layered silicate force field to simulate the adsorption of primary and quaternary amines with different chain lengths on the mica (001) surface, and calculated water molecules/amine ions and mica (001). The interaction energy of the surface. The calculation results show that the amine ion has the thermodynamic advantage that can sufficiently prevent the formation of the hydration layer, and can ensure the effective flotation process.
In addition to the cationic collector dodecyl acetate (DAA), Lo nghua Xu et al. also studied the adsorption mechanism of anionic collector (NaOL) and anionic and cationic mixed collector (NaOL+DAA) on the surface of muscovite. . They studied the adsorption of the above three agents on the surface of muscovite by single mineral flotation test, potentiodynamic test and flower fluorescence test. The results of flotation test showed that there was no capture effect of NaOL on muscovite alone; the recovery rate of DAA alone could be reduced from 80% (pH=2) to 50% (pH=11); NaOL+DAA could make white clouds The mother recovery increased from 80% (pH = 2) to 90% (pH = 11).
The results of potentiodynamic test and flower fluorescence test showed that the surface of muscovite was negatively charged in the range of pH 2-12. The single cationic collector could strongly adsorb on the surface of mica, while the single anion collector had no obvious adsorption. . In the anion-cation collector mixing system, the co-adsorption effect can enhance the adsorption of dodecylamine, because the presence of sodium oleate reduces the electrostatic repulsion between the mineral surface and the amine ion and enhances the hydrophobicity of the tail. The results of the molecular dynamics simulation agree well with the experimental results.
RK Rath and S. Subramanian provide a reference for studying the mechanism of action of inhibitors and mica. They used a combination of adsorption measurement, single mineral flotation test, potentiodynamic test, field emission scanning electron microscopy (EDAX), dissolution test and coprecipitation test on various methods of polysaccharide macromolecular inhibitor Gur gel in black. The adsorption of mica surface has been studied in detail. The results showed that the adsorption amount of Gurga gel on the surface of biotite increased with the increase of pH value. The adsorption isotherm accorded with the Langmuir adsorption equation, and the adsorption process was affected by hydrogen bonding and metal ion hydroxyl groups on the surface of Gum and biotite. The chemical reaction between the groups is dominated.
Mica flotation agent
1, collector
The collectors used for mica flotation are also different at different pulp pH values. Under acidic conditions, the cationic collector is an effective agent, such as a long carbon chain of ammonium acetate, and commonly used are dodecylamine and cocoamine. Under alkaline conditions, it is necessary to use an anionic and cationic collector in combination. In practice, a long carbon chain amine acetate cation collector and a fatty acid anion collector are commonly used.
Conventional collectors such as dodecylamine in the flotation of mica, the foam is difficult to break for a long time and is easy to stick, resulting in increased water consumption and dosage. In order to solve this problem, Deng Haibo et al. studied the dodecylamine and three kinds of seasonal hinge collectors dodecyltrimethylammonium chloride (1231) and tetradecyltrimethyl chloride by single mineral flotation test. The effects of ammonium (1431) and cetyltrimethylammonium chloride (1631) on the flotation behavior of muscovite, phlogopite and lithium mica, and four kinds of captures were compared by hydrophilic-hydrophobic balance (HLB) analysis. The foaming properties and solubility of the four collectors were compared using the two-phase foam test method. Taken together, 1431 can be used as an effective collector for flotation of lithium mica and phlogopite. In addition, some newly synthesized collectors are gradually being used in the flotation of mica, such as the new collectors 3ACH and ACH-B of sericite reported in the literature.
In the treatment of certain mica ores, the use of a single collector often does not yield good flotation indicators, so the researchers did some research on the combination of collectors. He Guichun et al. studied the lithium mica in the tailings of Yichun antimony ore and carried out the experimental study on the flotation of lithium mica by combined collector. The results showed that the ratio of LZ-00 to cocoamine was 2:1. The best indicator when combining flotation lithium mica. Huang Wan Fu et HT with a new agent selected from an organic lithium agent + amine + to replace the original organic amine recovered HC1 is lepidolite of a tantalum and niobium ore, concentrate grade and recovery are improved. Liu Shuxian and Wei Shaobo for the sericite in a graphite tailings, using dodecylamine and diesel as the collector, after a rough selection and four selections, the sericite concentrate can be obtained.
2, inhibitor
Inhibitors are mainly classified into gangue mineral inhibitors and mica mineral inhibitors. At present, there are many researches on inhibitors of gangue minerals. In the acidic cation collector flotation process, the action of sulfuric acid can inhibit quartz in addition to controlling the pH. Starch has different degrees of inhibition on all silicate minerals. Under acidic conditions, starch has the strongest inhibitory effect on the quartz structure of the framework structure, and the inhibition of feldspar minerals in the framework structure is second. The structure and the double-stranded structure minerals have a poor inhibitory effect, so starch can also be used as an inhibitor of the flocculating sericite minerals.
In the alkaline anion and cation collector flotation process, sodium carbonate and lignosulfonate are commonly used to inhibit gangue. As the most widely used siliceous gangue inhibitor, water glass is also used in mica flotation. Several new gangue inhibitors have also been reported in recent literature, such as F-1 and FY used in sericite flotation. Inhibitors of mica minerals are mainly used in some mica as gangues. At present, there are few studies at home and abroad. It is reported in the literature that large molecular weight organic inhibitors such as guar gum and carboxymethyl cellulose (CMC) can be effective. Inhibition of mica minerals.
Mica flotation process
1. Influencing factors of mica flotation
There are many factors affecting the flotation process, which can be summarized as follows:
The material composition and chemical composition of the mineral;
Slurry preparation;
Flotation pharmacy system;
Working conditions caused by the flotation machine;
Flotation process.
The factors that have a greater impact on the mica flotation include the ore size composition, the pulp pH value, and the composition of the gangue minerals. In recent years, researchers have conducted some studies on other factors affecting mica flotation, such as grinding media and metal cations in pulp. It is found that the above factors can activate or inhibit mica flotation.
2. Mica flotation process
(1) Mica flotation conventional process
Conventional methods for mica flotation include an acidic cation method, a basic anion, a cation method, and a combination flotation method. Many of the more widely used processes are now being modified and optimized on the basis of these several conventional processes. The acidic cation method is an effective method for recovering coarse mica. The upper limit of the recovered particle size can reach 14 mesh, but the ore must be delimed in advance. This method involves blending the slurry with sulfuric acid (solid concentration 40% to 45%) and floating the mica with the collector. When the pH of the slurry is 4, the flotation effect is best. Alkaline anion and cation flotation are effective methods for recovering mica in the presence of slime. The ore must also be delimed in advance to remove viscous minerals. The maximum particle size of this method is up to 20 mesh. The mica recovery rate is adjusted when the pH is 8. 0-10. 5 when the pH is 8.0. highest. The combined flotation method is to apply the above two methods to the mica flotation.
(2) Practical application of mica flotation
In actual production applications, the preliminary process flow needs to be determined according to the nature and characteristics of the actual ore, and the process is enriched and optimized through a series of conditional tests to obtain optimized technical and economic indicators. In production practice, flotation is mainly used for the recovery of crushed mica and fine-grained mica, especially mica resources in tailings.
(3) Joint process sorting mica
For the mica ore with complex ore properties, it is sometimes necessary to use a combination of flotation and other beneficiation processes to achieve the comprehensive utilization of useful minerals. Li Yongcong conducted a re-election experiment on the tailings of the Lingshou crushed mica mine. The process of first removing mud, re-selecting and recovering mica by shaker, magnetically recovering iron minerals, and finally flotation separation of feldspar and quartz was obtained. The muscovite concentrate with a yield of 27% can be obtained from quartz, feldspar, magnetite and zircon concentrate.
(4) Application of new flotation process and new equipment
With the gradual development of flotation theory research and equipment development, in order to better adapt to the special nature of ore, some new flotation techniques and equipment have also been applied to mica flotation, and also achieved good results. Different from the traditional froth flotation, the hydrophobic flotation can significantly improve the hydrophobicity of the mineral surface. This technology stirs the surfactant, neutral oil and mineral under high speed conditions, surface activation and shear agglomeration. The particle size of the target mineral is increased to form agglomerates, and the degree of hydrophobicity is increased, resulting in enhanced planktonicity, and the flotation recovery rate can be significantly improved. Luo Lin used this technology to purify sericite in the surrounding rock of a gold mine in Hebei Province. When the content of sericite in the ore is 20%, the sericite concentrate with 80.08% mica content and 43.16% recovery rate can be obtained. The recovery rate is increased.
3. Flotation separation of mica-like gangue minerals
As a widely distributed rock-forming mineral, mica is often associated with various mineral resources in gangue minerals, so it is often necessary to use flotation to separate useful minerals. Fang and Equality studied the separation of flotation and muscovite. Firstly, the floatability and surface electrical properties of the two minerals were studied by single mineral flotation test and surface dynamic potential test, and then the flotation separation test of artificial mixed ore under different pharmaceutical systems was carried out. The results show that the use of the cationic collector laurylamine or anion collector IM combined with lauric acid can effectively separate the artificial mixed minerals of the sillimanite and muscovite.
Conclusion
With the development of high-quality flaky mica resources, the application range of traditional wind selection and mechanical beneficiation process is bound to shrink gradually, and flotation will be more important in the mica beneficiation field due to its excellent adaptability and sorting effect. Status. In recent years, domestic and foreign mineral processing workers have carried out many meaningful work in the field of mica flotation, and have achieved a series of results, such as new flotation processes, new drug development and basic theoretical research.
However, there are still some questions to be resolved:
1 At present, the flotation of mica is mostly carried out under acidic or alkaline conditions, which puts high requirements on the treatment and equipment of the tailings, and lacks the process of flotation of mica under near-neutral conditions;
2 The research on the basic theory of mica flotation is not enough. The mechanism of action of some common collectors and inhibitors and mica remains unclear.
In the future research, we should strengthen the use of advanced analytical testing methods to study the mechanism of action of agents and mica, especially the mechanism of action of the regulator; strengthen the application range of molecular dynamics simulation, and partially replace the experimental research with simulation calculation. In addition, the use of combination agents, the application of the joint beneficiation process, and the development of new agents and new equipment are also very interesting research directions for the future mica flotation.
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