Raw ore powdering process

Abstract

The invention relates to the technical field of mineral separation, in particular to a raw ore pulverizing process which comprises a pulverizer and a powder concentrator, the pulverizer is material bed pulverizing equipment, and the powder concentrator is a V-shaped powder concentrator and / or a screening device; a selective crusher is arranged in front of the pulverizer and is used for pretreating raw ore; the raw ore comprises laterite type nickel ore, or smelting slag, or stone coal vanadium ore, or waste concrete, or alluvium type gold ore; according to the strength difference between the target mineral and gangue, the grinding force of the grinding machine is adjusted; after the raw ore is ground by the grinding machine, the raw ore is sorted by the powder concentrator, and according to the particle size of the material, coarse particle discarding tailings or fine particle discarding tailings are selected; in addition, the materials with the middle particle size are returned to the flour mill to be ground again; by applying the process, excessive grinding can be eliminated during powder preparation, pre-selection and enrichment are realized, the ore grade is improved, and finally the smelting cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of ore dressing, and in particular to a raw ore powder making process. Background Art

[0002] Ore dressing is the process of crushing and grinding the ore according to the physical and chemical properties of different minerals in the ore, and then separating the useful minerals from the gangue minerals by gravity separation, flotation, magnetic separation, electrostatic separation and other methods, and separating the various symbiotic (associated) useful minerals from each other as much as possible, removing or reducing harmful impurities, so as to obtain the raw materials required for smelting or other industries; Ore dressing can enrich the useful components in the minerals, reduce the consumption of fuel and transportation in the smelting or other processing processes, and make low-grade ores economically utilized.

[0003] For some difficult-to-select ores, sometimes the mineral processing method alone often fails to achieve satisfactory results or even fails to separate them, so it is necessary to adopt a combined mineral processing and metallurgical process for treatment; the combined mineral processing and metallurgical process is a process for treating ores by alternating mineral processing and metallurgical methods.

[0004] Chinese patent CN117120172A discloses a laterite nickel ore dressing equipment and process, the equipment includes: a cylindrical ore washer, a trough ore washer, a vibrating screen, a hydrocyclone connected to the trough ore washer and the vibrating screen, a first thickener connected to the hydrocyclone, a spiral chute connected to the hydrocyclone, a first ball mill connected to the spiral chute, and a second thickener connected to the first ball mill; the process includes: three-stage sorting and re-selection of the ore materials in sequence, settling the ore materials that meet the requirements after the three-stage sorting and re-selection, and crushing, grinding and settling the ore materials that meet the requirements. The ore is fully utilized, the waste of ore is reduced, and the nickel collection rate is improved.

[0005] In the process of implementing the embodiment of the invention, the inventors found that the prior art has at least the following defects: over-grinding is easily produced in the process of grinding the raw ore.

[0006] The over-grinding phenomenon refers to the fact that materials that have already reached the reasonable fineness requirements continue to be ground in the mill, resulting in the materials being too fine. The inventors have recognized that in the mineral processing industry, over-grinding usually manifests itself in the following aspects: (1) if the gangue minerals that should not be ground are also ground, they will be mixed into the high-value target minerals, causing ore depletion and bringing difficulties to sorting; (2) in addition, as the grinding time increases, the target mineral grains are easily over-grinded. If the target mineral is also over-grinded, the over-fine target mineral is easy to enter the tailings along with the gangue minerals, commonly known as running ore and running tailings, resulting in a decrease in recovery rate and unnecessary energy consumption. Therefore, it is urgent to provide a raw ore powder making process to solve the technical problem of over-grinding that is easy to occur in the prior art, so as to improve production efficiency and reduce production costs. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the present invention provides a raw ore milling process. In the milling (grinding) stage, a material bed grinding device is selected as a milling machine to replace the traditional tube mill, and the grinding force of the milling machine is adjusted according to the strength difference between the target mineral and the gangue, and the tailings are discarded in time to enrich the target mineral through selection. The purpose of the present invention is achieved through the following technical solutions: A raw ore powder making process, comprising a grinding mill and a powder concentrator, wherein: The grinding mill is a material bed grinding device, including an external circulation vertical mill or a roller press, wherein the external circulation vertical mill is a vertical mill without a separator; The powder classifier is a V-type powder classifier, and / or a screening device, wherein the screening device comprises a rotor-type powder classifier (32), a cylindrical screen, or a grading screen; The grinding force of the grinding mill is adjusted according to the strength difference between the target mineral and the gangue; after the raw ore is ground by the grinding mill, it is sorted by the powder concentrator, and coarse particles or fine particles are discarded according to the particle size of the material; and the material with an intermediate particle size is returned to the grinding mill and ground again; by applying this process, over-grinding can be eliminated during powder making, pre-selection enrichment can be achieved, and the ore grade can be improved.

[0008] In a specific possible implementation manner, a selective crusher is arranged before the grinding mill for pre-processing of the raw ore; the selective crusher comprises a drum crusher.

[0009] In a specific possible implementation scheme, a powder collecting device is arranged after the powder classifier, and the powder collecting device includes a cyclone separator and / or a dust collector, and the dust collector is a bag dust collector or an electric dust collector; the powder collecting device is used for product collection and environmental protection; after the system exhaust gas is purified, it is led out by an exhaust fan connected to the powder collecting device and discharged into the atmosphere.

[0010] In a specific possible implementation scheme, a regulating valve is provided on the dust collecting duct of the system, and the dust collecting duct includes a ventilation duct; the wind speed is adjusted and controlled by the regulating valve, and then the product fineness is adjusted.

[0011] In a specific possible implementation scheme, waste heat from production is utilized, or a hot air furnace is provided; a hot air valve is provided on the heating pipeline to adjust the amount of hot air; and a cold air valve is provided to adjust the temperature of the hot air; hot air is provided for raw ore powder production to achieve both grinding and drying.

[0012] In a specific embodiment, the raw ore includes laterite nickel ore, or smelting slag, or stone coal vanadium ore, or waste concrete, or alluvial gold ore.

[0013] In summary, the present invention has the following beneficial effects: (1) The microstructure of minerals is closely related to the mineralization conditions. The mechanical properties of minerals and gangues are different, and the differences are related to their respective microstructures. The mechanical strength of a material is a measure of its ability to resist external forces without being destroyed. When the mechanical strength of a material is poor, it means that its resistance to external forces is weak. When subjected to external forces, such as grinding, cutting and other mechanical processing, materials with poor mechanical strength are more likely to deform or break. The above reasons cause the parts with poorer strength to be more easily ground during the grinding process. Therefore, by adjusting the pressure of the grinding roller, the soft ore is crushed first, and the hard ore is kept intact as much as possible, rather than all broken, thereby eliminating over-grinding. For example, under normal circumstances, even the hardest mineral will not be harder than a steel ball. The steel ball hits the material indiscriminately, crushing all the soft and hard ores, and even the ones that do not need to be crushed temporarily are also crushed, thus causing over-grinding. When using grinding rollers to crush mineral particle clusters, the soft ore is always crushed first, and then the soft ore particles hide in the space supported by the hard ore to avoid further squeezing, thus eliminating over-grinding.

[0014] (2) After the minerals are crushed, the soft ore and the hard ore are different in size, so it is convenient to separate the two in advance. The present invention can separate the fine powder (mostly soft ore) in time through sorting, and additionally, it can also reduce the over-grinding of soft ore.

[0015] (3) The content of target minerals in soft ores and hard ores is often different. It is understandable that separation of soft ores and hard ores helps to enrich the concentrate and improve the grade of the ore.

[0016] In the prior art, over-grinding can also cause low mineral processing efficiency. After eliminating over-grinding, the present invention can not only achieve the beneficial effect of saving energy consumption, but also improve the mineral processing efficiency. Improving the mineral processing efficiency can be said to be an unexpected technical effect.

[0017] So, why can't the prior art achieve the above beneficial effects? The inventors realized that the reason is that the equipment and process of the prior art are defective, and there is no separation measure in the grinding process, which easily causes over-grinding of materials; over-grinding leads to the impoverishment of the target mineral (doping, mixing of gangue), and the easy selection becomes difficult during the selection, which increases the burden of subsequent sorting. If there is subsequent flotation, the amount of reagents used will increase, and the production cost is high. And / or, the ore is lost (the loss of concentrate), resulting in waste of resources and a decrease in recovery rate.

[0018] In the process of powder making, the present invention adopts a new process and adds separation measures, which can eliminate the phenomenon of over-grinding during powder making and reduce energy consumption; at the same time, by pre-selection and enrichment, the ore grade is improved, and part of the tailings are discarded, which can greatly reduce the ore processing volume in the subsequent process. In short, in the production process, collect in advance (recover useful minerals), discard as early as possible (discard tailings), and discard while walking, so as to reduce the cost of smelting; finally, the cost of smelting is reduced.

[0019] Through the above comparative analysis, it can be found that the traditional mineral processing technology is, in short, crushing, grinding, flotation and filter pressing; in the crushing and powder making stage, technical personnel in this field often only consider the dissociation of monomers and grind the raw ore into powder. They do not recognize the difference between the single particle crushing principle and the material bed crushing principle, nor do they realize the influence of the difference in mechanical properties between the mineral itself and the gangue on crushing. They ignore the control of crushing force and the selection of sorting time, resulting in over-grinding of materials; for ordinary technicians in this field, it is obviously difficult to understand the above knowledge and make improvements. This is also the reason why the relevant technology cannot achieve the beneficial effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flow chart of Embodiment 1 of the present invention; Figure 2 is a flow chart of Embodiment 2 of the present invention; Figure 3 This is a flow chart of Embodiment 3 of the present invention.

[0021] Description of the accompanying drawings: 1-drum crushing machine; 21-External circulation vertical mill; 22-Roller press; 31-V-type powder classifier; 32-rotor type powder classifier; 33-grading screen; 4-dust collector; 41-regulating valve; 42-exhaust fan; 5-hot air furnace; 51-hot air valve; 52-cold air valve. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments; based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention. It should be noted that the present invention can be implemented in a variety of different ways as defined and covered by the claims. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0023] At present, laterite nickel ore is mainly smelted by pyrometallurgical or hydrometallurgical processes to produce high-grade nickel matte or nickel-cobalt hydroxide (MHP) intermediate products respectively; if pyrometallurgical process is adopted, during the smelting process, smelting slag (molten slag) is discharged from the slag outlet. Usually, the slag is subjected to water quenching, crushing and sorting for many times; that is, the raw materials need to be smelted repeatedly to be continuously enriched and high-grade nickel-iron alloy is obtained; the present invention is suitable for grinding and powdering laterite nickel ore or smelting slag (including roasted ore).

[0024] The present invention has a simple structure, reasonable design and convenient implementation; in the embodiments of the present invention, a variety of optional implementation methods are provided, which can be selected according to actual needs. No matter which method is adopted, the existing technology is no longer used for the powder making process of specific minerals, and the problems in the existing technology can be solved and the corresponding effects can be achieved; the following embodiments can be applied to the powder making of laterite nickel ore or stone coal vanadium ore, and can also be applied to the resource recycling of waste concrete, or the pre-selection of alluvial gold mines, etc. Therefore, the application of the present invention includes but is not limited to the powder making process of laterite nickel ore.

[0025] Embodiment 1: In this embodiment, laterite nickel ore is ground into powder; as the finished product of the powder making stage, the powder is the raw material for smelting in the furnace, the free water content of the powder is about 1%, the crystal water content is 9% to 10%, and the residue on a 200-mesh sieve is 30%.

[0026] See also Figure 1 This embodiment provides a raw ore powder making process, including a grinding mill and a powder concentrator, wherein: In this embodiment, a selective crusher is arranged before the grinding mill, and the selective crusher includes a drum crusher 1 for pre-processing laterite nickel ore; the drum crusher 1 is a horizontally rotating cylindrical barrel, which is driven to rotate by a motor, and screen holes or screen bars are distributed on the barrel wall; the laterite nickel ore is fed from one end, wherein: the fine material leaks from the screen hole in the middle of the equipment and enters the grinding mill; the block material is discharged from the other end to achieve pre-discarding tailings; the tailings are low-grade lean ore and waste rock discarded as tailings; the tailings include pre-discarding tailings, which has the advantage of reducing the processing volume of subsequent grinding and sorting operations.

[0027] Further explanation is as follows. In this embodiment, the purpose of using the selective crusher is that: in laterite nickel ore, high-grade ore is fragile, while hard materials with obviously too high strength are often surrounding rocks or gangue; based on this characteristic, using a smaller crushing force can pre-separate the hard materials; in this embodiment, with the help of the drum crusher 1, the material is repeatedly dropped during the process of traveling, so that the target mineral can be broken by using a smaller crushing force, while the gangue remains intact, which is convenient for the separation of the two; after the pre-disposal of the tailings, the primary selection of the raw ore is completed; due to the large difference in the hardness of nickel ores in different regions, a nickel ore drop test must be performed before the selection of the equipment, and then the equipment specifications are determined according to the number of drops and the processing capacity of the nickel ore; Similarly, in the coal mining industry, the mined raw coal is often mixed with gangue. The gangue is hard and the raw coal is soft. If it is not crushed properly, the gangue will break into small pieces and mix into the raw coal, reducing the quality of the raw coal and making it difficult to pick. The drum crusher 1 has been used for crushing and screening raw coal in coal preparation plants. Selective crushers are used instead of manual gangue picking to mechanize gangue picking operations and reduce labor intensity.

[0028] In addition, in this embodiment, according to actual conditions, a medium-free mill (autogenous mill) can also be selected to act as the selective crusher. The medium-free mill is a grinding equipment that has both crushing and grinding functions. It uses the material to be ground as a medium and achieves crushing through mutual impact and grinding. The medium-free mill is named after this. Its greatest feature is that the raw ore from the mining field or the coarsely crushed ore no longer needs to pass through a crusher, etc., and can be directly fed into the mill; the medium-free mill can grind the material to -0.074mm at one time, and the content accounts for more than 20% to 50% of the total product; in the medium-free mill, its essence is to use the hard part of the raw material as a grinding body, and the soft raw material is always crushed first, so a similar effect can be achieved.

[0029] The laterite nickel ore that has completed the preliminary selection is fed into the grinding mill, which is a material bed grinding device, including an external circulation vertical mill 21 or a roller press 22, and the external circulation vertical mill 21 is a vertical mill without a separator; The main working parts of the vertical mill (vertical mill) are the grinding disc and the grinding roller. The motor drives the grinding disc to rotate through the reducer, and the grinding roller rolls around its own axis on the grinding disc. The material passes through the air-locking feeding device and the material falls to the center of the grinding disc through the material chute. Due to the action of centrifugal force, an annular material bed is formed and is clamped into the gap between the grinding roller and the grinding disc. It is crushed by the extrusion action, and at the same time, the shear force is generated due to the relative sliding, so that the material is ground finely; the vertical mill uses the grinding roller to squeeze the material on the grinding disc, and relies on the airflow to bring the particles that meet the fineness requirements out of the mill, and collect them through the dust collector to become the finished product; inside the vertical mill, the larger particles in the airflow fall back to the grinding disc for grinding under the action of gravity. This process must be carried out many times to achieve the required fineness; the roller press consists of two extrusion rollers that rotate synchronously in opposite directions, one is a fixed roller and the other is a movable roller; both the vertical mill and the roller press are material bed grinding equipment.

[0030] For a long time, in the mineral processing industry, tube mills are usually used as grinding equipment. The tube mills include ball mills. The ball mills are filled with a certain number of steel balls as grinding media in their cylinders. The main function of the steel balls in the ball mills is to impact and crush the materials, and they also play a certain grinding role. The grinding and crushing process of processing limonite laterite nickel ore will consume a lot of energy. The existing technology often uses ball mills, which have extremely low grinding efficiency and high energy consumption. According to the research and experimental measurements of grinding workers in various countries in the world, the grinding efficiency of tube mills is only a few percent, and the rest is the sound energy consumption, the wear energy consumption of grinding media and liner plates, etc. The fundamental reason is that tube mills usually adopt the principle of single-particle crushing. In single-particle crushing, each particle is crushed by contacting with the crushing equipment and being directly pressed or sheared by it, while material layer crushing is different from this. Different from the single particle crushing, the material bed grinding equipment adopts the material bed crushing (or material layer crushing) principle. Only a small number of particles are in direct contact with the crushing equipment. Under the action of pressure, the materials are squeezed and crushed. The crushing efficiency of the material layer crushing is high. The materials are crushed in the process of mutual squeezing. There is no unnecessary waste of energy, so it is energy-saving.

[0031] Furthermore, a vertical mill usually has its own separator, which can perform powder selection inside the mill; the present invention adopts an external circulation vertical mill 21, which is a vertical mill without a separator, that is, the present invention transfers the powder selection function to the outside of the mill, and can discharge the material with the required fineness and which does not need to be ground again in a certain period of time from the grinding mill in time, so as to meet the requirements of ore dressing; therefore, the ore is discharged in time and over-grinding will not occur.

[0032] The materials entering the mill have different abilities to resist damage due to different mineral structures. The main function of the steel balls in the ball mill is to impact and crush the materials. The impact strength is the same, and the parts that should not be crushed are often crushed more, so it is easy to produce over-grinding. As a material layer crushing equipment, the external circulation vertical mill 21 can adjust the crushing force; that is, the crushing force of the mill is adjusted according to the strength difference between the target mineral and the gangue; therefore, the raw ore is crushed by the mill, and the difference in the impact resistance of different minerals is used to gradually increase the pressure step by step, and the tailings are discarded in multiple times, which further avoids over-grinding.

[0033] For example, the associated spinel-type chromite in laterite nickel ore has a strong abrasive effect on the anti-corrosion layer of wet process equipment. Therefore, it is very necessary to carry out beneficiation and impurity removal of chromite. The essence of beneficiation and chromium removal in laterite nickel ore is the separation and enrichment of chromite and limonite. Regarding the differences between limonite and chromite, the prior art believes that they mainly exist in density and magnetism. However, in addition to this, the inventors realized that abrasion occurs because some minerals are not easy to break, and the difficulty of breaking minerals is determined by their mechanical properties. That is to say, of chromite and limonite, one is difficult to grind and the other is relatively easy to grind. Under the same grinding conditions, the coarseness will be different. The difference in particle size can be used to separate chromite and limonite.

[0034] For another example, anthracite is a carbonaceous shale that is highly decomposed in an oxygen-deficient environment. The humus it contains has chelating and adsorption effects. At the same time, due to the combined influence of the formation conditions of anthracite and the hydrothermal impregnation during rock formation, anthracite is often accompanied or enriched with more than 60 metal elements such as vanadium, molybdenum, nickel, and copper, and most of the metal elements exist in the form of sulfide ores. In some anthracites, one or several of these metal elements can often reach the boundary grade of their mineralization or the industrial grade of independent mining, making the anthracite have independent mining value. For example, vanadium-containing anthracite or anthracite vanadium ore is a very important one among them. The vanadium in anthracite mainly exists in trivalent form, replacing aluminum (III) in the lattice of aluminosilicates such as mica and garnet through isomorphic effects. The occurrence state of vanadium in anthracite determines that the vanadium extraction process of anthracite should start with the destruction of silicate minerals such as vanadium-containing mica and illite.

[0035] Microstructure determines mechanical properties. Generally, the melting point of island-structured silicate minerals is higher and the hardness is greater. This is because the ions in their structure are closely arranged, making the mineral structure relatively stable. This structural feature makes island-structured silicate minerals have higher thermal stability and mechanical strength. In other words, the strength of island-structured silicate minerals is obviously higher than that of layered and frame-shaped silicates. Similarly, mica-type minerals are easily peeled off due to their layered structure, and their strength is not higher than that of frame-shaped quartz sand. Under the same grinding force, mica-type minerals must be broken first. By adjusting the grinding force of the mill, mica-type minerals (rich in vanadium) are broken first, and quartz sand (poor in vanadium) is kept intact. After the two are separated, the quartz sand is discarded, which can improve the grade of vanadium in the ore. This is understandable. Similarly, by applying this embodiment, part of the gangue in laterite nickel ore, including chromite, can be removed to achieve nickel enrichment.

[0036] After being rolled by the external circulation vertical mill 21, the material is sorted by the powder classifier, and coarse particles or fine particles are discarded according to the particle size of the material; and the material with an intermediate particle size is returned to the grinding mill for rolling again; In this embodiment, the laterite nickel ore is fed into a powder classifier after being ground. The powder classifier is a V-type powder classifier 31. The V-type powder classifier 31 is composed of baffles arranged in a trapezoidal shape. The baffles are similar to the grid plates at the outlet of an air conditioner and have the functions of guiding flow and material. The material is fed from the upper feed port and is dispersed by the stepped inclined baffles arranged on the inlet and outlet sides to form a material curtain. The material to be sorted falls on a group of steps in a trapezoidal shape, and the sorting airflow passes through the steps. The airflow entering the machine passes through the material curtain from the air inlet and contacts the material. The material collides back and forth at the ends of the baffles on both sides to achieve the effect of breaking up the material blocks, fully exposing the fine powder and extending the residence time of the material curtain. This embodiment utilizes waste heat from production, or sets a hot air furnace 5, to provide hot air for the V-type powder concentrator 31. After the hot air is temperature-adjusted, it becomes the inlet airflow of the V-type powder concentrator 31. This embodiment sets a hot air valve 51 on the heating pipeline to adjust the hot air volume; and a cold air valve 52 to adjust the temperature of the hot air; hot air is provided for raw ore powder making to achieve grinding and drying; In this embodiment, after the laterite nickel ore enters the V-type powder concentrator 31, the coarse particles in the material are separated from the material under the action of gravity and fall down along the guide plate to be discharged; under the same grinding conditions, this part of the material cannot be ground, which is equivalent to the passive screening of the grinding machine; this shows that the coarse particles are most likely gangue minerals such as quartz, or spinel-type chromite that is relatively difficult to grind, etc.; therefore, this embodiment selects coarse particles for tailings, thereby improving the ore grade.

[0037] Then, through the V-type powder concentrator 31, the airflow separates the fine material from the material and transports it to the fine material outlet (i.e., the exhaust port), and the airflow carries the fine material out of the exhaust port and enters the screening device; In the present embodiment, the screening device comprises a rotor powder classifier 32, and the rotor powder classifier 32 generates a high-speed rotating airflow through a rotor; the material enters the powder selection chamber of the rotor powder classifier 32 along with the airflow, and the coarse and heavy particles in the material are thrown to the inner wall surface of the powder selection chamber under the action of the inertial centrifugal force, and lose kinetic energy after collision and slide down along the wall surface, and fall into the coarse powder collection cone, and the remaining particles are taken away by the rotating rising airflow, and when passing through the action area of ​​the large wind blade, under the impact of the large wind blade, another part of the coarse and heavy particles are thrown to the inner wall surface of the powder selection chamber, and lose kinetic energy after collision and slide down along the wall surface, and enter the coarse powder collection cone; after passing through the large wind blade, the medium and coarse powder and the fine powder continue to rise and pass through the vertical guide blades to enter the secondary powder selection area under the carrying of the rising airflow, and under the action of the strong and stable plane vortex generated by the rotating cage rotor, the medium and coarse powder in the dusty airflow is thrown to the vertical guide blades under the action of the centrifugal force, and loses kinetic energy after collision and falls into the medium and coarse powder collection cone, and is discharged from the medium and coarse powder pipe; In this embodiment, the coarse and heavy particles (coarse powder) and the medium coarse powder refer to materials with intermediate particle sizes, which are unqualified in particle size but have the potential to become target minerals, so they are returned to the grinding mill and crushed again; By adjusting the speed of the rotor, the particle size of the fine powder can be adjusted. The fine powder that meets the requirements is discharged with the air flow through the cage-shaped rotor and collected by the powder collection equipment to become the finished product. In this embodiment, a powder collecting device is arranged after the powder classifier, and the powder collecting device includes a cyclone separator and / or a dust collector 4, and the dust collector 4 is a bag dust collector or an electric dust collector, which is used for product collection and environmental protection; wherein the cyclone separator is also called a cyclone barrel or a cyclone dust collector, which is a dry gas-solid separation device that separates dust from the airflow by the centrifugal force generated by the high-speed rotation of the gas-solid mixture; the system exhaust gas is purified by the powder collecting device, and then led out by the exhaust fan 42 and discharged into the atmosphere; a regulating valve 41 is arranged on the dust collecting pipeline of the system, and the dust collecting pipeline includes a ventilation pipeline; the wind speed is adjusted and controlled by the regulating valve 41, and the product fineness can also be adjusted; to prevent wear, the regulating valve 41 should be installed in a place with low dust concentration or a position with limited abrasion of dust particles.

[0038] In summary, this embodiment can separate part of the gangue minerals such as calcite and quartz in advance when grinding the anthracite vanadium ore to achieve vanadium enrichment; or, when grinding the laterite nickel ore, at least part of the spinel-type chromite that is difficult to grind can be separated; it is worth mentioning that the definition of the target mineral and the gangue is only relative. For example, when refining nickel metal, chromite is the gangue; when refining chromium metal, only chromite is the high-value target mineral.

[0039] Embodiment 2: This embodiment is suitable for extracting aggregate (crushed stone) and recycled sand powder from waste concrete; the stockpile of waste concrete accumulates year by year, and the waste concrete is essentially a man-made mineral. Rational use of its resources can alleviate environmental pressure and provide construction aggregate resources.

[0040] See also Figure 2 This embodiment also provides another raw ore powder making process, including a grinding mill and a powder separator, and a selective crusher is arranged in front of the grinding mill, and the selective crusher includes a drum crusher 1. Waste concrete often contains soil, which is fragile. In contrast to embodiment 1, the drum crusher 1 is used as a soil removal screen; this embodiment separates the soil from the waste concrete in advance and then discards the soil; that is, the pre-treated waste concrete is fed into the grinding mill; after the soil is removed by mechanical scrubbing, the product quality can be guaranteed.

[0041] The difference from Example 1 is that in this embodiment, (1) The grinding mill is a roller press 22, and the roller press 22 includes a roller crusher; the roller crusher uses two rollers rotating in opposite directions to crush the material; the roller crusher is composed of a fixed roller, a movable roller, a bracket, a motor and a safety spring; the roller surface is mostly smooth, and the bearing of the movable roller can move along the frame and is supported by a strong safety spring. When a particularly hard object falls into it, the bearing automatically moves away and spits out the object.

[0042] (2) The crushed waste concrete is sent to the powder classifier, which includes a grading screen 33. The grading screen 33 is a bar vibrating screen, a drum screen, etc., which uses a screen to screen the material.

[0043] Pre-treated waste concrete often contains aggregate (crushed stone), bricks, masonry mortar, and plastering mortar, and their strengths decrease in sequence; when rolling, controlling the strength of the roller crusher can make the bricks and mortar break first, thereby peeling off the crushed stone; when the rolling force is appropriate, the crushed stone will not crack, and the quality is guaranteed. After screening, the screened materials are used for sand making; the remaining materials are returned and continue to be rolled until they become sand powder; the sand powder circulates in the system and acts as an abrasive until the fineness meets the requirements, and can be collected by the dust collector 4 and discharged from the system. This embodiment can make waste concrete into crushed stone first, and the remaining part can be made into sand and sand powder. Among them, the value of sand and sand powder is far less than that of crushed stone. Therefore, this embodiment can maximize the resource recycling of solid waste.

[0044] Embodiment 3: Alluvial gold ore is a muddy and sandy sedimentary mineral containing gold formed by long-term weathering of vein gold ore. It is a mineral with industrial mining value. In the ore deposit of the sedimentary gold ore, due to the washing during the formation process, the useful minerals with high specific gravity are relatively concentrated. In addition to native gold, it usually includes platinum, cassiterite, magnetite, ilmenite, chromite, rutile, wolframite, scheelite, rare earth and other minerals; the gangue minerals usually include quartz, garnet, tourmaline, barite, mica, etc.; among them, the particle size of natural gold is usually between 0.1 mm and 4 mm, and the shapes are various. Ore deposits usually contain fine mud, which is mainly composed of non-metallic minerals, including kaolin, montmorillonite, hydromica and other fine mud minerals. Montmorillonite is a layered mineral composed of extremely fine particles of hydrous aluminum silicate, also known as colloid stone and microcrystalline kaolinite; as well as fine mud minerals such as calcite and feldspar, whose particle size is usually greater than 5 microns and the content is more than 3%. The fine mud wraps the gold particles, and as the mud content increases, the difficulty of washing the gold ore becomes increasingly greater.

[0045] See also Figure 3 This embodiment also provides another raw ore powder making process, including a grinding mill and a powder concentrator, and a selective crusher is arranged in front of the grinding mill, and the selective crusher includes a drum crusher 1; the drum crusher 1 is used to remove large pieces of gangue such as pebbles in the ore bed, and then the remaining mud and sand mixture is sent to the grinding mill for repeated rolling.

[0046] The difference from Example 1 is that (1) In this embodiment, the grinding mill is a roller press 22; (2) Materials that are too coarse (pebbles, etc.) and materials that are too fine (fine mud) are discarded, and sand is repeatedly crushed as a potential rich ore to separate the coarse concentrate or concentrate; (3) Fine mud is collected and discarded as tailings.

[0047] In the prior art, the ore dressing preparation work of alluvial gold mines mainly includes wet crushing, ore washing and wet screening of placer gold ore. In this process, large particles of gangue and fine mud can be discarded, which is convenient for subsequent classification and re-selection to recover gold. The disadvantage is that it consumes a lot of water. The present invention is applied to the pre-selection of alluvial gold mines, which can realize dry separation; it can achieve the effect of saving water resources and is suitable for arid areas.

[0048] In this embodiment, the medium-coarse powder (also called sub-coarse powder) of the powder separator is collected as coarse concentrate; the powder separator is a V-type powder separator 31, and the coarse powder separated by the V-type powder separator 31 can be subjected to magnetic separation or electric separation to obtain concentrate and medium ore, and the medium ore is returned to the roller press 22 for further rolling; wherein, the magnetic separation technology utilizes the magnetic difference of minerals for separation, and is particularly suitable for gold ore containing magnetic minerals; this technology effectively separates magnetic minerals from non-magnetic minerals in gold ore through a high-gradient magnetic separator or a roller magnetic separator; in the gold ore beneficiation process, magnetic separation is usually used to remove iron impurities that affect the subsequent purification process, thereby improving beneficiation efficiency.

[0049] The fine powder separated out at last is collected by the dust collector 4 as the tailings of the lean ore. Alternatively, in an additional embodiment, the fine powder is used as the finished product of the powder making section; for example, the silicate minerals are ground into powder using this process, and the powder can be used in the building materials industry. Unlike conventional oxide ores and sulfide ores, alluvial gold mines often have completed monomer dissociation, gold has good ductility, is relatively difficult to be ground into powder, and has a large specific gravity; the deposits of alluvial gold mines are often rivers, which are rich in silicate minerals, such as pebbles, sand, etc., which are essential raw materials for the building materials industry. According to these characteristics of the raw materials, gold can be panned while making powder, killing two birds with one stone, and can achieve unexpected results.

[0050] Similarly, this process can be applied in the crushing and beneficiation of smelting slag to crush the slag and recover the metal, which can overcome the problem of over-grinding, improve the metal recovery rate, and obtain slag micro-powder.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A raw ore powder making process, characterized in that: It includes a grinding mill and a powder classifier, wherein: The grinding mill is a material bed grinding device, comprising an external circulation vertical mill (21) or a roller press (22), wherein the external circulation vertical mill (21) is a vertical mill without a separator; The powder classifier is a V-type powder classifier (31), and / or a screening device, wherein the screening device comprises a rotor-type powder classifier (32), a cylindrical screen, or a grading screen (33); The grinding force of the grinding mill is adjusted according to the strength difference between the target mineral and the gangue; after the raw ore is ground by the grinding mill, it is sorted by the powder concentrator, and coarse particles or fine particles are discarded according to the particle size of the material; and the material with an intermediate particle size is returned to the grinding mill and ground again; by applying this process, over-grinding can be eliminated during powder making, pre-selection enrichment can be achieved, and the ore grade can be improved.

2. The ore powder making process according to claim 1, characterized in that: A selective crusher is arranged before the grinding mill for pre-processing the raw ore; the selective crusher comprises a drum crusher (1).

3. A raw ore powder making process according to claim 1 or 2, characterized in that: A powder collecting device is arranged after the powder classifier, the powder collecting device comprising a cyclone separator and / or a dust collector (4), the dust collector (4) being a bag dust collector or an electric dust collector; the powder collecting device is used for product collection and environmental protection; after being purified, the system exhaust gas is drawn out by an exhaust fan (42) connected to the powder collecting device and discharged into the atmosphere.

4. The ore powder making process according to claim 3 is characterized in that: A regulating valve (41) is provided on the dust collection pipeline of the system, and the dust collection pipeline comprises a ventilation pipeline; the wind speed is regulated and controlled by the regulating valve (41), thereby adjusting the fineness of the product.

5. A raw ore powder making process according to claim 1 or 2, characterized in that: Utilize waste heat from production or set up a hot air furnace (5); set up a hot air valve (51) on the heating pipeline to adjust the hot air volume; and a cold air valve (52) to adjust the temperature of the hot air; provide hot air for raw ore powder making to achieve powder grinding and drying.

6. A raw ore powder making process according to claim 1 or 2, characterized in that: The raw ore includes laterite nickel ore, smelting slag, stone coal vanadium ore, waste concrete, or alluvial gold ore.

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