Six common methods of mineral processing

Commonly used mineral processing methods include re-election, flotation, magnetic separation, electro-election, chemical beneficiation, and bacterial beneficiation.

Microbial beneficiation

Also known as "bacterial beneficiation." It mainly uses iron oxide bacteria, sulfur oxidizing bacteria and silicate bacteria to remove iron, sulfur and silicon from minerals. Iron-oxidizing bacteria can iron. SOx sulfur-oxidizing bacteria can, using bacterial decomposition of silicate clay mineral removal from aluminum silicon. In addition to desulfurization, de-ironing and desiliconization, it can also be used to recover copper , uranium , cobalt , manganese and gold .

Bacterial beneficiation, also known as bacterial leaching, utilizes the catalytic action of certain microorganisms to dissolve the metal in the ore. For example, there is a sulfur-oxidizing bacterium which has the ability to oxidize elemental sulfur to form sulfuric acid in solution. Another type is iron oxidizing bacteria, which has the ability to accelerate the oxidation of FeSO4 to Fe2(SO4)3, which greatly increases the Fe2(SO4)3 content in the solution. The H2SO4 and Fe2(SO4)3 solutions are effective solvents for sulfide ore and other minerals.

For example, pyrite is generally contained in polymetallic sulfide ore. In the presence of water and oxygen, pyrite is slowly oxidized and FeSO4 and H2SO4 are formed. The reaction formula is:

In the presence of aerobic and sulfuric acid, ferric bacteria oxidize FeSO4 to Fe2(SO4)3 at a very fast rate. The reaction formula is:

Fe2(SO4)3 can dissolve metals in minerals. For example, when it acts on chalcopyrite, it can form CuSO4, FeSO4 and S. The reaction formula is:

The FeSO4 formed by the above reaction can be reoxidized by the iron oxidizing bacteria to form Fe2(SO4)3, and the reaction is repeatedly circulated in the solution, and the leaching action is continuously performed. If there is sulfur oxidizing bacteria in the solution, the S formed by the reaction will be oxidized by sulfur oxidizing bacteria to form H2SO4, which is more effective for the leaching of ore. The reaction formula is:

Advantages of bacterial leaching:

(1) Simple equipment and convenient operation, (2) Adapted to the treatment of lean ore, waste ore, tailings and slag, etc., (3) Comprehensive leaching, comprehensive recovery of various metals, (4) Current copper, uranium bacteria The leaching process is relatively mature, and the copper leaching solution can recover the copper therein by extraction-electrowinning or iron displacement-flotation.

The main disadvantage of bacterial leaching is that the cultivation of bacteria is troublesome and the leaching period is relatively long.

There are many examples of application of bacterial beneficiation in China, such as a copper mine in Guangdong, bacterial leaching in an old mining area in a copper mine in Anhui, and a copper mine in Hunan. This paper introduces the application of bacterial leaching to treat copper-bearing tailings in a copper mine in Hunan.

A large number of flotation tailings and re-election tailings exist in a copper mine in Hunan. The flotation tailings contain 0.11%~0.20% copper; the re-election tailings contain 2.25%~1.50% copper, and both tailings contain Rare metal.

The process of bacterial leaching of tailings is shown in Figure 7-7. Since the tailings have a fine particle size, the leaching tank is used for leaching. The acid, acidified water and alkaline gangue in the ore are first added. When the pH reaches about 2.0, the leaching solution containing the high-iron (Fe3+) is added for cyclic leaching until the concentration of copper and rare metals in the immersion liquid is low. Then add a copper, rare metal bacteria infusion, when the concentration of the leachate is lower, and then wash for 2 to 3 days to discharge.

The tailings leaching time is 20 days, and the leaching results are listed in Table 7-2. After the rare metal in the leachate is adsorbed, the tail liquid contains about 1.5~2.0 g/L of copper, and the copper is precipitated into sponge copper by the iron replacement method. The chemical reaction formula is:

(1) The higher the copper content of the replacement liquid, the better, the iron content should be as low as possible, pH = 1.8%~2.0;

(2) When the pH value of the solution is about 1.5, the copper concentration is 2~4g/L, the iron consumption ratio is 2.0~2.5 times of copper; when the pH value is about 2, when the copper concentration is high, the iron consumption ratio is 1.5 times that of copper;

(3) Iron replacement time, which is related to temperature, quality and quantity of scrap iron, acidity of solution and replacement method. Generally, when the temperature is greater than 20 ° C, in the case of ventilation, the replacement can be completed in six hours;

(4) Discharge the tail liquid immediately after the replacement, adjust the Fe2+ concentration and acidity in the tail liquid, and return to the bacterial culture solution for use.

The main technical and economic indicators:

(1) The total recovery of copper is 70%~75%; the total recovery of rare metals is 75~80%;

(2) Sponge copper grade 60%~650%;

(3) 40%~45 kg of sulfuric acid per ton of mine; 2.5 tons of iron per ton of copper;

(4) The cost of converting pure metal copper per ton is 2,000 yuan.

Reselection method

The re-election method is to classify minerals based on the difference in relative density of minerals (commonly referred to as specific gravity). Mineral pulls with different densities are subjected to fluid dynamics and various mechanical forces in the moving medium (water, air and heavy rolling), resulting in suitable loose delamination and separation conditions, so that different density of ore particles can be separated.

Gravity beneficiation (referred to as re-election) is based on the density of various minerals (commonly referred to as specific gravity), and thus the gravity, fluid dynamics and other mechanical forces in the moving medium, so as to achieve the process of sorting ore groups by density. . Mineral particles and shapes will affect the accuracy of sorting by density.

Due to the difference in density of various mixed ore particles, the sedimentation speed of the moving medium (such as water, heavy medium with a density greater than water, and air, etc.) is not, and the degree of movement is also different, thereby achieving separation of minerals and all re-election. The process is based on the sedimentation law of the ore particles in the selected medium.

The common features of various re-election processes are:

1 There must be a difference in density (or particle size) between the ore particles;

2 sorting process is carried out in the moving medium;

3 Under the combined action of gravity, fluid dynamics and other mechanical forces, the ore group is loose and stratified by density (or particle size);

4 points of good layer material, separated under the movement of moving media, and get different final products.

Re-election is a long-established method of mineral processing. In the Han Dynasty of China, it was known to re-elect the tin ore. Since the re-election method is simple, low cost, and increasingly well-developed, so the re-election law is still the main method of beneficiation of tungsten tin and coal. It has also been widely used in the selection of certain non-ferrous metals, ferrous metals, precious metals and non-metallic minerals.

Granular sorting processes (such as grading, dewatering, etc.) in gravity beneficiation are indispensable in almost all concentrators.

Flotation method

The flotation method is based on the difference in physical and chemical properties of the mineral surface, and is treated by a flotation agent, and the mineral is selectively attached to the bubble to achieve the purpose of sorting. Non-ferrous ore dressing, such as copper, lead, zinc, sulfur, molybdenum and other miners to use flotation process, some ferrous metals, rare metals, and some non-metallic minerals, such as graphite ore, apatite, also flotation Law selection.

In the flotation process, flotation agents are added to the slurry to improve and adjust the floatability of the mineral. Many minerals that are not naturally floatable are not floatable or floatable after being acted upon by flotation agents, or vice versa. In order to artificially control the floatability of minerals. So some people say that flotation reagents are the mainstay of flotation technology, which makes sense. The development of flotation reagents is inseparable from the development of flotation process. The production practice of flotation promotes the research of flotation reagents, and the development of flotation reagents promotes the development of flotation technology.

Five major pharmacy

The use of flotation reagents and their basic types are shown in Table 6-2.

Flotation agents are used to adjust and control the flotation process. The main uses of the agent are: (1) to enhance the difference in the floatability of the minerals, thereby separating the minerals from each other and from the useful minerals and gangues. (2) Increasing the speed and strength of the useful ore particles attached to the bubbles, (3) improving the formation conditions of fine and diffuse bubbles in the slurry, and creating conditions for the formation of stable mineralized foam on the surface of the slurry.

Table 6-2 Uses of flotation reagents and their basic types

Gold silver ore flotation

The choice of flotation process is usually determined according to the nature of the gold and silver ore and the specifications of the product. The common principle process has the following five types:

The selection of the flotation process is usually based on the nature of the gold and silver ore and the specifications of the product. The common principle processes are as follows:

(1) Flotation + flotation concentrate cyanide The sulfide ore containing gold and silver quartz veins is subjected to flotation to obtain a small amount of concentrate, and then cyanidation treatment. Compared with the whole mud cyanidation process, the flotation concentrate cyanide has the advantages of not requiring fine grinding of all ore, saving power consumption, small plant area, and capital investment.

(2) Flotation + concentrate roasting + roasting cyanidation This process is commonly used to treat insoluble gold- arsenic ore, gold- bismuth ore and gold-pyrite ore with extremely high sulfide content. The purpose of roasting is Remove elements such as arsenic and antimony that are harmful to the cyanidation process.

(3) Flotation + flotation concentrate ore fire treatment Most of the polymetallic sulfide ore containing gold and silver is treated by this method. During the flotation, gold and silver enter the gold mines such as copper and lead which are closely related to them, and then send them to the smelting plant to recover gold and silver.

(4) Flotation + flotation tailings or medium ore cyanidation + flotation concentrate in situ roasting cyanide This scheme is used to treat quartz vulcanization containing antimony gold, pyrrhotite, chalcopyrite and other sulfide minerals In the ore and ore, the sulfide ore can be floated out as a concentrate, and then the gold and silver in the sulfide are exposed and calcined and then cyanated. Because the middle and tailings after flotation generally contain gold and silver, they are still cyanide.

(5) Flotation of raw ore cyanide + cyanide tailings When the gold and silver in the ore and sulphide are not completely recovered by cyanidation, the slag after cyanidation is floated again, which can improve the recovery rate of gold and silver.

Segregation-flotation

Segregation-flotation is a combination of pyrochemical treatment and flotation. For example, the separation-flotation of refractory copper oxide ore is to break the ore into a certain particle size, mix a small amount of salt (0.1-1.0%) and pulverized coal (0.5-2.0%), and heat it to about 900 degrees by oxygen. The copper in the ore is precipitated on the surface of the carbon particles in a metal state, and the calcine is cooled by oxygen and then floated by grinding to obtain a copper concentrate.

The biggest advantage of the segregation-flotation method is that it can solve the ore that cannot be treated by conventional beneficiation methods, and it can comprehensively recover useful metals in the ore. For example, in copper ore, when the ore contains a large amount of cyanite, azurite and bound copper, or contains a large amount of slime, the flotation method of such ore often has a low index, and the segregation rule is More effective.

The segregation method can also process mixed ore of copper oxide ore and copper sulfide ore, and can comprehensively recover useful metals such as gold, silver and iron. In addition, compounds of several metals such as gold, silver, nickel , aluminum, cobalt, rhodium , palladium , iridium , tin, etc. are easily reduced and are prone to generate volatile chlorides, and are also suitable for treatment by isolation.

The disadvantage of the segregation method is that the cost is high, the capital construction investment is large, and the production cost is also high. It is estimated that the infrastructure investment of the segregation method is about twice that of the same capacity flotation plant, and the production cost is also 2-3 times higher. Therefore, when the oxidized copper ore is difficult to be treated by the separation method, it is considered that the copper grade in the ore should be greater than 2% to obtain a better economic effect. So the separation method is only used to solve ore that cannot be treated by other methods. Therefore, before using this method, a comprehensive study should be conducted on the treated ore. If it can be treated by other methods, it is not appropriate to use the segregation method.

Three stages of copper segregation

The segregation process is more complicated. Although many experimental work has been done on the segregation of copper, there are still some different opinions on some issues. Most believe that the segregation process of copper oxide ore is roughly divided into three stages.

(1) In the decomposition stage of salt, during the separation process, first, the crystal water in the salt and the ore forms hydrogen chloride at a temperature of 700 °C. Its reaction formula is as follows:

(2) During the volatilization stage of cuprous chloride, hydrogen chloride reacts with copper oxide minerals to produce volatile cuprous chloride. There are many types of copper oxide minerals. For the sake of simplicity, simple Cu2O is used as a representative. The formula is:

(3) In the reduction and isolation stage, the copper chloride vapor is reduced by hydrogen (hydrogen adsorbed by the carbon particles) to form isolated copper and covers the carbon particles. Its reaction formula is:

The copper (Cu) is efficiently recovered by flotation, and the hydrogen chloride (regenerated HC1) produced by the reduction of cuprous chloride can continue to react with the copper oxide mineral to form cuprous chloride, which causes the above reaction cycle to occur cyclically.

There are many factors affecting the segregation process, among which the following are the main factors.

(1) Ore properties The ore particle size and the material composition of the ore should affect the segregation process, especially when dealing with calcareous gangue, especially calcite , limestone, etc., the formation of calcium oxide will hinder the segregation of copper.

(2) Temperature influence The temperature directly affects the chlorination reaction rate, and accurate temperature control is an important condition for the separation process. The upper limit of the separation temperature depends on both the ore properties and the heat exchange conditions, as well as the economic factors. If the separation temperature is high, not only fuel is wasted, but also the sintering of the material occurs, and the kiln skin phenomenon occurs. If the temperature is below the separation temperature, the segregation effect is deteriorated.

(3) Residence time The residence time of the material in the separation kiln depends on the volume of the kiln, the relative density of the material, and the passing speed of the material. In general, the residence time of the material in the kiln should be sufficient to achieve a high recovery rate.

(4) Reducing conditions The reducing conditions have a great influence on the segregation process, and moderate reducing conditions are beneficial to the progress of the chlorination reaction.

(5) The amount of chlorinating agent The salt itself has no effect on the chlorination reaction, and the initiating reaction of the segregation is hydrogen chloride produced by the hydrolysis of the salt, and the chlorination reaction rate is proportional to the hydrogen chloride pressure. If the amount of salt added is too small, the supply of hydrogen chloride cannot meet the needs of the initial chlorination reaction rate. Excessive use of salt is also harmful, it will dissolve cuprous chloride, reducing the recovery of segregation.

(6) Water vapor steam plays an important role in the decomposition of chlorinating agent and the formation of hydrogen chloride. Experiments have shown that if the ore loses crystal water, the segregation process cannot proceed.

Magnetic separation

Magnetic separation is a beneficiation method that uses the difference in magnetic properties of various minerals to sort in the magnetic field of a magnetic separator. As shown in Figure 4-1, when the ore particles with different magnetic properties pass through the magnetic field of the magnetic separator, they are inevitably subjected to magnetic and mechanical forces. Since the magnetic particles with strong magnetic properties and the magnetic particles with weak magnetic properties are different in magnetic force, different trajectories are generated, so that the ore particles are divided into two or more separate beneficiation products according to their magnetic properties.

Magnetic separation is widely used in the selection of ferrous ore, the selection of colored and rare metal ores, the recovery of medium in heavy medium ore dressing, the removal of iron-containing impurities from non-metallic mineral raw materials, the removal of iron objects, the protection of crushers and other equipment. Recycling scrap steel from steel slag produced by smelting and removing pollutants from production and domestic sewage.

In recent years, due to the development of high field strength and high gradient magnetic separators, the application fields of magnetic separation methods are still expanding, such as removal of chemicals, paramagnetic particulate impurities in drugs, and the like.

At present, there are many types of magnetic separators used at home and abroad, and the classification methods are different. According to different characteristics, the following classification methods are available.

(1) According to the magnetic source of the magnetic separator, it can be divided into a permanent magnet magnetic separator and an electromagnetic magnetic separator.

(2) According to the strength of the magnetic field can be divided into:

1 weak magnetic field magnetic separator, magnetic field surface magnetic field strength Ho = 72 ~ 136 kA / m, magnetic field force HgradH = (2.5 ~ 5.0) × 1011 amp / 2 / 3;

2 medium magnetic field magnetic separator, the magnetic field strength of the magnetic pole surface Ho = 160 ~ 480 kA / m;

3 Strong magnetic field magnetic separator, the magnetic field strength of the magnetic pole surface is Ho = 480~1600 kA/m, and the magnetic field force HgradH=(1. 5~6. 0) × 1013A 2/m3.

(3) The medium according to the sorting process can be divided into a dry magnetic separator and a wet magnetic separator.

(4) According to the type of magnetic field, it can be divided into constant magnetic field, pulsating magnetic field and alternating magnetic field magnetic separator.

(5) According to the structure of the body, it is divided into belt magnetic separator, cylinder magnetic separator, roller magnetic separator, disc magnetic separator, ring magnetic separator, cage magnetic separator and pulley magnetic separator. .

Among them, the magnetic field strength and the selection of the medium structure are mainly distinguished.

Weak magnetic separator mainly used for sorting ferromagnetic minerals, such as magnetite, titanium magnetite, ferrosilicon. In the past, the industry was mostly electromagnetic magnetic system. The shape of the body was mostly tubular and belt type. At present, it is mostly permanent magnet magnetic system and cylindrical shape, and it is widely used in wet applications.

In the past, in the field of strong magnetic field magnetic separator, the dry magnetic separator was used to sort non-ferrous metals and rare metal minerals. In the past ten years, in order to select low grade, fine inlay size and minerals. Various types of wet magnetic separators have been developed, such as ring type, cage type, and disc type.

The medium magnetic field magnetic separator is mainly used for sorting locally oxidized ferromagnetic ore.

Magnetic fluid dressing

Magnetic fluid beneficiation is a new process for magnetic selection, including magnetohydrostatic separation and magnetohydrodynamic separation.

It uses a special flow ratio (such as a paramagnetic solution, a ferromagnetic colloidal suspension and an electrolyte solution) as a sorting medium, and uses these special fluids to generate a "weighting" effect under the combined action of a magnetic field or a magnetic field and an electric field. A beneficiation method that separates different minerals by the difference in magnetic properties and density of minerals or the difference in magnetic properties, electrical conductivity and density. When the magnetic difference between minerals is small, and the difference in density or conductivity is large, the magnetic fluid beneficiation method can achieve effective separation.

Including magnetic fluid static separation and magnetohydrodynamic separation: the latter is a combination of a magnetic field (uniform or non-uniform) and an electric field, with a strong electrolyte solution as the separation medium, according to the density and specific magnetic susceptibility between the minerals A method of beneficiation that separates different minerals and is suitable for the separation of ore that does not require high recovery; the former has similarities with heavy liquid separation, and is a paramagnetic liquid and ferromagnetism. The colloid (water-based liquid or organic solvent liquid) suspension is a sorting medium. Under the action of gravity field, centrifugal force field and magnetic field, the floating and sediment separation solid particles can be used as one of the selected methods in diamond dressing.

Since the magnetic fluid has magnetic properties, if a variable density gradient distribution is generated under different magnetic fields, the weighting medium in the conventional heavy medium beneficiation can be replaced for efficient heavy medium dressing, which is magnetic fluid sorting.

Electroporation

The full name of the power beneficiation method. A method of sorting in a high voltage electric field according to the difference in conductivity of ore minerals and gangue mineral particles. Including electrical selection, electrical grading, triboelectric charging sorting, high gradient sorting, dielectric sorting, electric dust removal and so on.

The electrical properties of minerals are the basis for electrification. The electrical properties of the two minerals are different and it is possible to conduct electrical selection. The parameters indicating the electrical properties of the mineral mainly include the dielectric constant, electrical conductivity and relative electrical resistance, electrothermal property, specific conductivity and rectification of the mineral.

The dielectric constant is represented by the symbol ε, and the larger ε indicates the better conductivity of the mineral, and vice versa. In general, those with ε > 10~12 or more belong to the conductor and can be separated by the usual high-voltage electrification, and those below this value are difficult to sort by conventional electro-selection.

Generally, the mineral resistance referred to in the electric selection is the resistance when the mineral particle size is d = 1 mm, that is, the ohmic value. When the mineral resistance is less than 106 Ω, it indicates that the conductivity is better, the resistance is greater than 106 Ω and less than 107 Ω, the conductivity is medium, and the resistance is greater than 107 Ω. The conductivity is poor and cannot be separated by conventional electric separation.

The specific conductivity of minerals is the amount that is easy for electrons to flow or flow out of the ore. It is usually expressed by the ratio of the lowest voltage of the electron flow on the ore particles to the lowest voltage of the electrons flowing out on the graphite. The larger the value, the more minerals are made. The higher the voltage flowing out, the worse the conductivity.

Some minerals are only used as conductors when the high voltage electrode is negatively charged, while another pad mineral is only used as a conductor when the high voltage electrode is positively charged, and some minerals can be used as conductors regardless of the positive and negative voltage of the high voltage electrode. The mineral is separated, and this property of minerals is called rectification. The minerals that only get negative electricity are called negative rectification, such as quartz and zircon ; the minerals that only get positive charge are called positive rectification, such as calcite; whether the electrode is positive or negative, the mineral can obtain electric charge, called full rectification. Sex, such as cassiterite, magnetite, etc.

List of dielectric constants and resistances of various minerals

In order to improve the sorting effect of the electric separator, different preparations should be taken according to the nature of the materials and operating conditions before electrification. Commonly used preparation operations include drying, de-sludge and grading of materials, and surface treatment.

First, dry

There are many methods for drying. In the laboratory, a constant temperature drying oven can be used. In the production, there are commonly used drum dryers, air flow dryers, boiling dryers, and drying ovens. The requirements of the product, equipment manufacturing, floor space, labor conditions, etc. can be selected according to the nature of the material.

Second, de-sludge and grading

In the cylindrical electric separator, since the centripetal force required for the circular movement of the coarse ore particles is large, the coarse ore particles are preferentially enriched in the conductor product, and the fine ore particles are preferentially enriched in the non-conductor product. In order to avoid this sorting by particle size, the material often needs to be sieved before electro-election. When the material contains a large amount of fine ore particles (less than 40 microns), the separation process is affected because the fine ore particles will stick to the grounded cylinder electrode, generate dust and cause spark discharge between the high voltage electrode and the ground electrode. Destruction, so it needs to be degreased beforehand. The grading of the electrified material is generally carried out by dry sieving, sometimes by wind grading, or in a box type electric sorter.

Third, mineral surface treatment

The effect of electrification depends to a large extent on the surface condition of the mineral. The surface condition of minerals can sometimes be artificially altered by pretreatment methods, for example, by treatment with chemicals to remove certain components from the mineral surface, allowing the mineral surface to selectively adsorb the agent to form a new surface film. Selectively change the conductivity of different minerals to facilitate sorting.

The electric field used in the electric separator has three kinds of electrostatic field, corona electric field and composite electric field.

The electrostatic field is often generated by a high-voltage DC power source, which can attract or repel the force of the charged ore particles, so that the ore trajectory is different and the sorting purpose is achieved. The corona electric field is an electric field widely used in electric selection. It uses two electrodes separated by a certain distance, one of which is a wire electrode with a small diameter (or a corona pole) with a large curvature and a high voltage DC negative voltage. Or positively charged, another extremely flat or large diameter drum (ground), where a corona electric field of partial discharge is generated, which can charge the ore between the two electrodes. The composite electric field refers to the electric field combined with the corona electric field and the composite electric field, and is a commonly used electric field in the electric field of the electric separator, which can greatly improve the sorting effect.

At present, electrical selection mainly has the following applications.

(1) a colored, black, and the selection of rare metals e.g., separation of cassiterite and scheelite; magnetite, hematite, chrome ore, manganese ore sorting; Tanni ore, iron ore Chin, rutile, Separation of monazite; sorting of gold, etc.

(2) Sorting of non-metallic minerals, for example, sorting of quartz and feldspar ; sorting of graphite, diamond, apatite, coal, and asbestos .

(3) Production of ultra-pure iron concentrates For example, the use of electric selection to produce high-quality iron concentrates containing Fe greater than 66% and containing SiO2 less than 3% is advantageous for reducing coke ratio, saving energy and reducing costs.

(4) The classification of various materials can be classified according to the shape and particle size of the materials.

(5) Sorting of broken metal powder and fine particles in other insulating materials.

(6) Removal of non-ferrous metal materials from plastics.

(7) Recovery of useful metals such as copper and aluminum from municipal solid waste.

(8) Selection of grain and other cereals to remove impure debris.

(9) Sorting of tea leaves.

Chemical beneficiation

Chemical beneficiation is a mineral processing process based on the chemical nature of mineral and mineral components, the use of chemical methods to alter the mineral composition, and then other methods to enrich the target components.

For example, copper ore containing malachite is leached with dilute sulfuric acid. The mineral component is changed, that is, the malachite becomes a copper sulfate solution. Metal copper (sponge copper) can be obtained by replacing the copper ions in the solution with iron filings. Chemical beneficiation is one of the effective methods for the treatment and comprehensive utilization of some poor, fine and miscellaneous mineral raw materials. It is also one of the important ways to make full use of mineral resources and solve the three wastes (waste water, waste residue and waste gas) treatment, turn waste into treasure and protect the environment.

The treatment targets and purposes of chemical beneficiation are the same as those of physical ore selection. They are all processing mineral raw materials and enriching, separating and utilizing the mineral resources of the target components. However, its application range is wider than physical beneficiation. In addition to handling difficult raw ore, it can also handle intermediate products, tailings and coarse concentrates that cannot be processed by physical beneficiation methods, and can recover useful components from “three wastes”.

Therefore, chemical beneficiation has a promising future, but it should be pointed out that the current chemical dressing generally has a high problem of wood formation, mainly because the chemical beneficiation process requires a large amount of chemical test Liu, so under normal conditions, it can be treated by physical beneficiation method. It is not advisable to use chemical beneficiation methods.

Chemical beneficiation has different operations according to different processes. The typical chemical beneficiation process generally includes six main operations such as preparation.

(1) Preparation The operation is the same as the physical beneficiation method, including the processing of crushing and sieving, grinding and grading, and mixing of ingredients. The purpose is to break the material to a certain particle size, prepare suitable fineness and concentration for the next operation, and sometimes use physical beneficiation method to remove some harmful impurities or pre-enrich the target mineral, so that the mineral raw materials and chemical reagents are mixed. Mix well. If it is treated by fire, it is sometimes necessary to dry or sinter the material to create favorable conditions for the next job.

(2) Calcination The purpose of roasting is to change the chemical composition of the ore or to remove harmful impurities, and to change the target mineral (component) into a form that is easy to leach or facilitate physical beneficiation, and prepare conditions for the next operation. The calcined products include calcined sand, dry dust, wet dust collecting liquid and mud, and the useful components can be recovered according to the composition and properties thereof.

(3) Leaching operation This operation is based on the nature of the raw materials and the process requirements, so that the useful components or impurity components are selectively dissolved in the leaching solvent, thereby separating the useful components from the impurity components or separating the useful components. , creating conditions for the recovery of useful components from the leachate or leach residue for the next step.

(4) Solid-liquid separation operation This is the same as the dewatering operation of physical beneficiation products. However, the solid-liquid separation of chemical ore leaching slurry is more difficult. Generally, the leaching slurry is treated by sedimentation, filtration and classification to obtain the next A clear solution for the work process or a solution containing a small amount of fine ore particles.

(5) Purification operation In order to obtain a high-grade chemical concentrate, the leachate is subjected to purification and separation by a chemical precipitation method, an ion exchange method, a solvent extraction method, or the like to remove impurities, thereby obtaining a purification solution having a high useful component.

(6) Preparation of chemical concentrate operation Extracting useful metals (components) from the leachate to obtain chemical concentrates, generally by chemical precipitation method, metal replacement method, electrowinning method, carbon adsorption method, ion exchange or solvent extraction method In some cases, physical beneficiation can also be used. The principle flow of a typical chemical beneficiation can be represented by Figure 7-1.

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