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Beneficiation process
Author：管理员 Publish in：2024-07-01 10:59:13 Page view (975)
Memo：In order to select the useful minerals from the ore, the ore must first be crushed so that the useful minerals in it and the time to reach monomer dissociation. Sometimes in order to meet the requirements of subsequent operations on the size of the material, it is also necessary to add a certain crushing operation in the middle.
Technological process
First, prepare homework before the electionIn order to select the useful minerals from the ore, the ore must first be crushed so that the useful minerals in it and the time to reach monomer dissociation. Sometimes in order to meet the requirements of subsequent operations on the size of the material, it is also necessary to add a certain crushing operation in the middle. The preparation work before the selection is usually carried out in two stages: crushing and screening operation and mineral classification operation. The crusher and the screening machine are mostly combined operation, and the mill and the classifier often form a closed cycle. They are the main mechanical equipment composed of the crushing workshop and the grinding workshop.
Crushing: The process of crushing the ore block with a particle size of 500 ~ 1500mm extracted from the mine to a particle size of 5 ~ 25mm. There are crushing, crushing, splitting, etc., generally according to coarse crushing, medium crushing, fine crushing in three stages.
Grinding: mainly grinding and impact. Grind the crushed product to a particle size of 10 ~ 300μm. The particle size of the grinding is determined according to the particle size of the useful mineral in the ore and the separation method used. Commonly used grinding equipment are: rod mill, ball mill, autogenous mill and semi-autogenous mill. Grinding operations have high energy consumption, usually accounting for about half of the total energy consumption of beneficiation. Since the 1980s, various new lining plates and other measures have been applied, and the grinding efficiency has been improved and the energy consumption has been reduced.
Screening classification: According to the size of the sieve surface, the material is divided into different particle size levels called screening, which is often used to deal with coarse-grained materials. According to the different sedimentation rate of particles in the medium (usually water), the material is divided into different equal grades, called grading, for materials with smaller particle size. Screening and classification is to separate the appropriate particle size of the material in the crushing process, or the material is divided into different particle size levels.
Ore washing: In order to avoid the mud in the mud mineral raw material clogging the crushing and screening equipment, it is necessary to wash the ore. If the raw material contains soluble useful or harmful ingredients, it should also be washed. Ore washing can be carried out in the scrubbing machine or in the screening and grading equipment.
Second, select homework
The mineral raw materials are separated by grinding operation, so that useful minerals and gangue are separated, or various useful minerals are separated from each other. This is the main part of mineral processing. Sorting operations include gravity sorting, flotation, electric sorting, sorting and chemical sorting.
reselection
In the medium (mainly water) flow, the different specific gravity of mineral raw material particles is used for sorting. Yes, jig, shaking table, chute selection, etc. Gravity separation is the main method for separating wolstenite, cassite, placer gold, coarse-grained iron and manganese ore. It is also widely used to select rare metal placers. The suitable size range of gravity separation is wide, from several hundred millimeters to less than one millimeter, the dressing cost is low, and the environmental pollution is less. Where the mineral particle size is within the above range and the specific gravity difference between components is large, gravity is the most suitable. Sometimes, you can use gravity (mainly heavy media selection, jigging, etc.) to remove part of the waste stone, and then use other methods to reduce the cost of mineral processing. With the increase of lean ore and fine mineral raw materials, the gravity separation equipment tends to be large-scale and multi-layered, and the use of composite motion equipment, such as centrifugal separator, shaking tilting machine, shaking chute, etc., to improve the gravity separation efficiency of fine particle materials. The material of 20μm can be effectively separated by gravity separation. Gravity separation is the most important coal separation method.
flotation
The difference of water wettability (hydrophobicity or hydrophilicity) on the surface of various mineral raw materials is used to select. Usually referred to as foam flotation. There are few natural hydrophobic minerals, and collectors are often added to the pulp to enhance the hydrophobic properties of the minerals to be surfaced. Add various adjustment agents to improve selectivity; Add foaming agent and aerate to produce bubbles, so that hydrophobic mineral particles attached to the bubbles, floating separation. Flotation can usually deal with materials less than 0.2 ~ 0.3mm, in principle can select a variety of mineral raw materials, is one of the most widely used methods. Flotation can also be used for sorting out smelting intermediate products, ions in solution (see), and treating wastewater. In addition to the use of large flotation machines, there are also some new methods to recover fine materials (less than 5 ~ 10m). For example, selective flocculation-flotation, a flocculant is used to selectively form a certain fine particle material into a larger size of floc, and then separated by flotation (or desliming) method; Shear flocculation-flotation, high intensity stirring after adding collector, etc., to make fine minerals form floc reflotation, carrier flotation, oil agglomeration flotation, etc.
Machine selection
Boiling separator is a collection of flotation, centrifugal gravity separation, inflatable flotation, jump titanium as one, as long as the specific gravity difference in 0.05 can separate minerals, computer remote control of high degree of automation, adjustable speed. It can desliming, agglomerating and carrier flotation. There is no magnetic sorting can be selected another kind of separator.
Magnetic separation
The different magnetic properties of mineral particles are used for sorting in non-uniform magnetic fields. Strong magnetic minerals (magnetite and pyrrhotite, etc.) are separated by a weak magnetic field magnetic separator; Weak magnetic minerals (hematite, siderite, ilmenite, wolframite, etc.) are separated by high magnetic field magnetic separator. The weak magnetic field magnetic separator is mainly an open magnetic system, mostly composed of permanent magnets, and the strong magnetic field magnetic separator is a closed magnetic system, and the electromagnetic magnetic system is multi-purpose. Weak magnetic iron minerals can also be changed into strong magnetic minerals by magnetizing roasting, and then separated by a weak magnetic field magnetic separator. The structure of magnetic separator has cylinder type, belt type, rotary ring type, disk type, induction roll type and so on. The magnetic pulley is used for presorting massive strong magnetic ore. The main development trend of magnetic separation is to solve the problem of recovery of fine and weak magnetic minerals. The Jones wet high-intensity magnetic separator with tooth plate concentrated magnetic medium, invented in the 1960s, promoted the selection of weak magnetic minerals. In the 1970s, the invention of high-gradient magnetic separators with high magnetic field gradient and strength with steel wool or steel mesh as the concentrated magnetic medium and superconducting magnetic separators with low-temperature superconductors instead of normal temperature conductors provided a good prospect for the recovery of fine-grained weak magnetic minerals.
Electric separation
The difference of electrical properties of mineral particles is used for sorting in high voltage electric field. It is mainly used for sorting conductor, semiconductor and non-conductor minerals. According to the electric field, the separator can be divided into electrostatic separator, corona separator and composite electric field separator. According to the charging method, it can be divided into contact charging electric separator, corona charging electric separator and friction charging electric separator. The size range of the electric separator is narrow, the processing capacity is low, and the raw materials need to be dried, so the application is limited; But the cost is not high, the sorting effect is good, less pollution; Mainly used for the selection of coarse concentrate, such as separation scheelite, cassiterite, zirconite, rutile, ilmenite, tantalum niobite, monazite and so on. Electrical separation is also used for the classification and dust removal of mineral raw materials. The development trend of electric separation is to develop equipment with large processing capacity and high efficiency for sorting fine grained materials.
select
Including hand picking and mechanical picking. It is mainly used for pre-selection and removal of waste rock. Hand selection is manual selection based on the external characteristics of minerals. This ancient mineral processing method is still used in some mines today. Mechanical sorting includes: ① light sorting, using the difference of mineral optical characteristics; ② X-ray sorting, using the characteristics of fluorescence under X-ray irradiation; (3) Radioactive sorting, using the natural radioactivity of uranium, thorium and other minerals. Electrical sorting and magnetic sorting using mineral conductivity or magnetism began to appear in the 1970s.
Chemical separation
Using the different chemical properties of minerals, using chemical methods or the combination of chemical and physical methods to separate and recover useful components, chemical concentrate is obtained. This method is more adaptable than the usual physical dressing method, the separation effect is good, but the cost is higher, and it is often used to deal with mineral raw materials, intermediate products or tailings that are difficult to deal with or cannot be dealt with by physical dressing methods. With the increasing number of mineral raw materials with complex composition, difficult to select and fine particles, the application of combined physical and chemical mineral processing process has been paid more and more attention. Examples of successful application of chemical separation include cyanide extraction of gold, acid leaching - precipitation - flotation, segregation - flotation treatment of copper oxide. The application of technologies such as ion exchange and bacterial leaching has further promoted the development of chemical separation. Its development trend is to develop more effective leaching agents and extractants, develop biochemical methods, reduce energy consumption and cost, and prevent environmental pollution.
In addition, there are mineral raw materials in the inclined plane movement or collision, the difference between the friction coefficient and the collision recovery coefficient is used to select other <A friction and bounce selection.
Third. Dehydration operation after selection
Most mineral processing products contain a lot of water, which is very bad for transportation and smelting processing. Therefore, before smelting, the water in the mineral processing product needs to be removed. Dehydration operations are often carried out in the following stages:
1) Concentration Concentration is the action of gravity or centrifugal force, so that the solid particles in the mineral processing products precipitate, so as to remove part of the water operation, concentration is usually carried out in the concentrator.
2) Filtration filtration is to make the slurry through a permeable but not permeable solid particles of the interval layer, to achieve solid-liquid separation of the operation. Filtration is a further dehydration operation after concentration, usually carried out on a filter.
3) Drying Drying is the final stage of dehydration. It is based on the principle of heating evaporation to reduce water operations. However, it is only used when the dehydrated concentrate still needs to be dried. Drying operations are generally carried out in dryers, and other drying devices are also used.
The auxiliary workshop composed of concentration, filtration, drying and other processes becomes the dewatering workshop.
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