CN109513521B - Mineral processing technology for recovering iron from asbestos tailings - Google Patents

Mineral processing technology for recovering iron from asbestos tailings Download PDF

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CN109513521B
CN109513521B CN201910072216.1A CN201910072216A CN109513521B CN 109513521 B CN109513521 B CN 109513521B CN 201910072216 A CN201910072216 A CN 201910072216A CN 109513521 B CN109513521 B CN 109513521B
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iron
asbestos
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CN109513521A (en
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王玉亮
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王玉亮
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B03SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03BSEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
    • B03B7/00Combinations of wet processes or apparatus with other processes or apparatus, e.g. for dressing ores or garbage
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B03SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03BSEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
    • B03B9/00General arrangement of separating plant, e.g. flow sheets

Abstract

The invention discloses a beneficiation process for recovering iron from asbestos tailings, which comprises the following steps: crushing the asbestos tailings after primary screening, screening again after crushing, adding water into the materials with the granularity of less than 10mm after secondary screening, and performing next-stage treatment, wherein the materials with the granularity of more than 10mm are returned to continue crushing; a ball mill and a grader are adopted, the concentration of the graded ore pulp of the material is controlled to be 7-25%, and the concentration of the ore pulp of ball milling and ore grinding is controlled to be 75-85%; a magnetic separator is adopted to absorb iron-containing minerals in the material and send the iron-containing minerals to the next process; discharging the materials which are not absorbed into a tailing pond as tailings; classifying the iron-containing minerals by adopting a cyclone, carrying out cyclone concentration on the materials with the particle sizes of more than 250-plus-325 meshes, then carrying out secondary ore grinding, and carrying out secondary magnetic separation on the materials with the particle sizes of less than 250-plus-325 meshes; finally, dehydrating by a disc type vacuum filter to obtain a fine iron powder product. The beneficiation process for recovering iron from asbestos tailings provided by the invention has the advantages of high beneficiation efficiency and low cost and energy consumption.

Description

Mineral processing technology for recovering iron from asbestos tailings
Technical Field
The invention relates to the technical field of beneficiation processes, in particular to a beneficiation process for recovering iron from asbestos tailings.
Background
Chrysotile, also known as serpentine asbestos, is a class of minerals in non-metallic ores. The asbestos deposits are serpentine deposits containing cotton, the average industrial grade of which is between 3 and 6 percent, and due to the low grade, asbestos beneficiation can produce a large amount of serpentine tailings. Because the mining history is long and the mines are numerous, the inventory of the asbestos tailings accumulated in China is more than 10 hundred million tons. The serpentine contains 6-10% of iron oxide ore, and more than 80% of the iron oxide ore is magnetic mineral. Because the asbestos tailings are crushed in multiple sections during the asbestos separation, the granularity of the asbestos tailings is less than or equal to 30mm, the grade of iron in the asbestos tailings is not high, but the iron separation still has a certain economic benefit, and the serpentine mineral contains various non-ferrous metal minerals such as nickel oxide, cobalt oxide and the like besides magnetite. The minerals are symbiotic with magnetite, and various non-ferrous metal minerals in the serpentine can be simultaneously selected during iron selection, so that the recovery and utilization of the multi-metal minerals in the asbestos tailings are realized. Therefore, the method has certain comprehensive benefits in the iron selection of the asbestos tailings.
The existing iron separation process of asbestos tailings basically adopts a common magnetic separation process, and the basic flow can be briefly described as the processes of crushing, multi-section ore grinding, multi-section grading, multi-section magnetic separation and dehydration. The process has poor adaptability to the iron selection operation of asbestos tailings, and has undesirable effect, the most direct appearance of the process is that the recovery rate of iron is low (only 50-60%), the grade of iron concentrate is low (52-56%), the beneficiation efficiency is not high, and the cost and the energy consumption are high.
Disclosure of Invention
The invention aims to provide a beneficiation process for recovering iron from asbestos tailings, which aims to solve the problems in the prior art, and has the advantages of high iron recovery rate, high grade of iron concentrate, high beneficiation efficiency, low cost and low energy consumption.
In order to achieve the purpose, the invention provides the following scheme:
the invention provides a beneficiation process for recovering iron from asbestos tailings, which comprises the following steps:
step one; pretreating, crushing asbestos tailings after primary screening, screening again after crushing, adding water into the materials with the granularity of less than 10mm after secondary screening, and feeding the materials with the granularity of more than 10mm back to the next treatment device for continuous crushing;
step two; grinding the ore for the first time; adopting a grid ball mill with phi 2.2 multiplied by 4.5m and a double-helix classifier with the model of phi 1.2 multiplied by 12m, controlling the concentration of classifying ore pulp of the material to be 7-25% and the concentration of ore pulp of ball milling and grinding to be 75-85%;
step three; first-stage magnetic separation; a barrel-type permanent magnetic separator is adopted to absorb iron-containing minerals in the material and send the iron-containing minerals into the next process; discharging the materials which are not absorbed into a tailing pond as tailings;
step four; cyclone classification; classifying the iron-containing minerals by adopting a polyurethane cyclone, concentrating the materials with the particle sizes of more than 250-plus-325 meshes by cyclone, then entering a second-stage ore grinding process, and directly entering a second-stage magnetic separation process for the materials with the particle sizes of less than 250-plus-325 meshes;
step five: and repeating the second step, the third step and the fourth step until the iron-containing minerals are subjected to three-stage magnetic separation, and then dehydrating through a disc type vacuum filter to obtain the fine iron powder product.
Optionally, a magnetic gravity separation step is also included between the magnetic separation and the cyclone classification; the magnetic-gravity separation adopts a magnetic-gravity separator, the diameter of the magnetic-gravity separator is 3.5m, the height of the magnetic-gravity separator is 3.0m, the magnetic field intensity of a bottom magnetic disk is 1300MT, and the stirring speed is 7 r/min.
Optionally, in the step one, the material after secondary screening further comprises a step of removing asbestos, wherein an alternating flow state machine is adopted in the step; in the second step and the fifth step, the materials after the first-stage ore grinding and the second-stage ore grinding are subjected to asbestos removal operation by adopting an alternating flow state machine; and (4) performing final asbestos removal operation on the materials subjected to the three-section ore grinding by adopting a cylindrical screen.
Optionally, a cylindrical screen is arranged on a tail water flow path of the alternating flow state machine after the second-stage ore grinding, and is used for collecting asbestos and returning the asbestos to the iron-containing ore pulp.
Optionally, the method also comprises an asbestos recycling step, wherein the asbestos removed after being screened by the alternating flow state machine and the cylinder is recycled; firstly, 4 parallel cylindrical sieves are adopted to carry out spraying type first-stage screening purification; secondly, two parallel cylindrical sieves are adopted for spraying type two-stage screening and purification, then one 4 groups of cyclone units are adopted for cyclone desanding, and finally a filling type filter is adopted for dehydration.
Optionally, the magnetic gravity separator comprises a cylinder, wherein the side wall of the upper end of the cylinder is respectively connected with a tail water discharge hole and an overflow groove, a vertical feeding sleeve and a stirring shaft are arranged in the cylinder, and the top end of the stirring shaft is arranged at the top of the cylinder through a stirring shaft bearing seat; the stirring shaft is symmetrically provided with a plurality of stirring scrapers, the bottom of the barrel is provided with a magnetic disk, a conical part is arranged below the magnetic disk, the conical part is hermetically connected with the bottom of the barrel, a water supply pipe disc is arranged above the conical part, and the bottom of the conical part is provided with a second closed discharger.
Optionally, the magnetic disk is of a disk-shaped structure with a permanent magnet inside and a magnetically permeable and wear-resistant material outside, and the diameter of the magnetic disk is smaller than that of the inner cylinder of the cylinder; the permanent magnets are arranged in the magnetic disk along the radial direction according to the magnetic poles of S-N-S-N.
Optionally, four stirring scrapers are symmetrically arranged on the stirring shaft, and each of the four stirring scrapers is of an involute structure.
Compared with the prior art, the invention has the following technical effects:
the invention makes the solid-liquid two-phase flow in the machine body generate wave motion with impact force under the action of pulse compressed air, can make the inclusion or agglomerate break in the motion of repeated air pressure impact, material collision and up-and-down rolling, and simultaneously the carpolite, iron-containing particles and fiber are separated in one time in the machine body, the asbestos separation efficiency can reach 98 percent, thereby effectively solving a series of adverse effects on magnetic separation and ore grinding operation caused by mixing asbestos wool and asbestos bundles which are continuously cleaved in section-by-section ore grinding in the process of selecting iron from asbestos tailings.
During the iron selection, the asbestos is recovered and the quality of the asbestos reaches the product standard, so that the separation, purification and utilization of the asbestos in the mineral separation process are realized, and the mineral separation comprehensive economic effect is better.
The medium magnetic agglomeration equipment (preferably the medium magnetic agglomeration equipment with stirring and capable of making ore pulp move in a rotational flow mode) used by the invention can effectively separate clay mineral particles without iron in the iron separation process, and can also collect the magnetic iron-containing mineral particles which are wrapped by the clay mineral and are not separated in the magnetic separation process of the magnetic separator.
The invention can make the grade of the selected iron concentrate powder reach 62 percent and the recovery rate of iron reach 75 percent. The recovery rate of the asbestos reaches 98 percent, the quality of the asbestos product reaches and exceeds the requirement of the national standard GB/T8071-708, and the comprehensive economic benefit is obvious.
No toxic, harmful or heavy metal substances are generated in the beneficiation process, and no secondary pollution is caused. The water in the process is recycled, and the water is recovered in a centralized manner due to the adoption of the sectional dehydration process among the working procedures, so that the utilization rate of the water is higher. The process is a wet operation, does not produce dust pollution and realizes the cleaning in the production process.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic flow diagram of an embodiment of a beneficiation process to recover iron from asbestos tailings;
FIG. 2 is a schematic flow diagram of an embodiment of a beneficiation process to recover iron from asbestos tailings;
FIG. 3 is a schematic flow diagram of an example beneficiation process to recover iron from asbestos tailings;
FIG. 4 is a schematic diagram of a magnetic gravity separator of a beneficiation process for recovering iron from asbestos tailings;
FIG. 5 is a top view of a magnetic gravimetric separator of a beneficiation process to recover iron from asbestos tailings;
in the figure, 1 is a tail water discharge hole, 2 is a stirring bearing seat, 3 is an overflow groove, 4 is a stirring shaft, 5 is a feeding sleeve, 6 is a stirring scraper, 7 is a magnetic disc, 8 is a second closed discharger, and 9 is a water supply coil pipe.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a beneficiation process for recovering iron from asbestos tailings, which aims to solve the problems in the prior art, and has the advantages of high iron recovery rate, high grade of iron concentrate, high beneficiation efficiency, low cost and low energy consumption.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
In each step of iron separation, the processes of alternating flow separation, magnetic gravity separation and magnetic separation, namely, the three-step type mineral separation process consisting of alternating fluidization, magnetic separation, magnetic gravity separation, classification and ore grinding, are adopted at the same time. The method is characterized in that no chemical agent is used in the beneficiation process, no special requirement is required for water, and the pH value is not required to be adjusted. The method is also characterized in that asbestos remained in the asbestos tailings and asbestos bundles which are continuously cleaved after section-by-section grinding are separated in time, and the adverse effect of the asbestos on iron selection in ore pulp is eliminated. The technology adopts an independently developed alternating flow state machine. The magnetic gravity ore dressing equipment is used for solving the adverse effect of clay minerals in ore pulp on the grade of iron dressing. A equipment for solving iron powder is choice adopts drum-type magnet separator. The equipment for classifying and concentrating the ore pulp adopts a cyclone classifier. The ore grinding equipment adopts a ball mill. The dewatering equipment adopts a disc type suction filter.
The technological process is also characterized in that the asbestos separated from each iron separation operation section is subjected to wet separation of dust removal and sand removal, so that the asbestos is purified, the standard of asbestos products is met, the asbestos products are obtained, the purpose of comprehensively utilizing tailings is achieved, and the economic benefit is better than that of singly selecting fine iron powder. The asbestos purifying process adopts two-stage sieving to remove dust, one-stage cyclone to remove sand and dewatering process. The screening and purifying operation adopts a spray type cylinder screen, the desanding operation adopts a plurality of groups of cyclones, and the dewatering operation adopts a filling type plate and frame filter.
Example one
The material used in this example is the tailings of an asbestos ore dressing plant, the asbestos content in the tailings is 3-3.5% (excluding asbestos bundles), the magnetite (TFe) content is 8.5%, and the moisture content of the tailings is about 3%.
As shown in figure 1, tailings are uniformly fed into screening operation by an ore bin according to the ore feeding amount of 2 tons/hour, screening equipment before crushing is an electromagnetic vibrating screen, the diameter of a screen hole is 30mm multiplied by 30mm, the area of the screen is 2.5m multiplied by 1.5m, ores which are not less than 30mm after classification enter a vertical shaft type crusher, ores which are less than 30mm enter grinding operation, and the model of the vertical shaft type crusher is a phi 750 four-layer vertical shaft type crusher. The crusher has the advantages of small damage to asbestos fibers and contribution to protecting the length of the asbestos fibers. The crushing granularity of the vertical shaft is 10mm, and the mesh opening of the electromagnetic vibration sieve behind the crusher is 10 multiplied by 10 mm. Returning and crushing the materials with the grain diameter larger than 10mm, and feeding the materials with the grain diameter smaller than 10mm into a first-stage ore grinding operation.
The first-stage grinding equipment is 2 grid ball mills of phi 2.2 multiplied by 4.5m, and the grading equipment is 2 double-screw classifiers of phi 1.2 multiplied by 12 m. The granularity of the first-stage ball milling is controlled to be 4-20 meshes. The concentration of the classified ore pulp is 7-25%, and the concentration of the ore pulp of ball milling ore is 75-85%.
The first-stage magnetic separation equipment is a cylinder type permanent magnetic separator, the size of a roller of the magnetic separator is phi 1.2 multiplied by 2.4m, and the magnetic field intensity is 350 mt. The two ore dressing rollers are arranged in parallel, the minerals absorbed by the magnetic separation roller are iron-containing minerals and enter the next ore dressing flow, and the minerals which are not absorbed are discharged into a tailing pond as tailings.
Because the target granularity of the secondary grinding is 250-325 meshes, the granularity of the ore pulp subjected to the primary magnetic separation is controlled to be 250-325 meshes through classification of cyclone classification, the particles larger than the granularity enter the secondary grinding after cyclone concentration, and the materials smaller than the granularity directly enter the secondary magnetic separation operation. The cyclone group consists of 6 polyurethane cyclones with diameter of 250 mm. The second-stage ore grinding equipment is an overflow ball mill with the diameter of 2.2 multiplied by 4.5 m. The two sections of magnetic separation equipment perform magnetic separation in the same section, and the two sections of magnetic separation equipment are parallel. The materials on the magnetic separation are subjected to cyclone classification, and the falling materials are thrown. The target granularity of the three-stage grinding is 380-400 meshes, so the cyclone classification before the three-stage grinding is controlled to be 380-400 meshes, materials with the particle size larger than the target granularity are subjected to cyclone concentration and three-stage ball milling and are ground, and the materials with the particle size smaller than the target granularity directly enter a three-stage magnetic separator for selection. The cyclone group consists of 4 polyurethane cyclones with diameter of 30 mm.
The three-stage ore grinding equipment is an overflow ball mill with the diameter of 2.2 multiplied by 4.5 m. The three-stage magnetic separation operation is 2 phi 800 multiplied by 700 permanent magnet drum magnetic separators, two of which are parallel and have the magnetic field intensity of 350 MT. And dehydrating the product obtained after the three-stage magnetic separation by using a disc type vacuum filter (two discs) to obtain the fine iron powder product.
70 tons of tailings (with the average grade of 8.5%) are added in the iron separation operation of the process, the produced refined iron powder is 1.3 tons (dry basis), the grade of the refined iron powder is 54%, the average grade of the tailings is 5%, the grade of the raw ore is 8.5%, and the ore separation recovery rate is 45.3%.
Example two
The materials used in this example were the same as in example one. As shown in fig. 2, the difference between this embodiment and the first embodiment is that, in order to improve the grade and the mineral separation recovery rate of the final iron concentrate, clay minerals must be separated in time in three-stage separation operations, so that on one hand, the mineral separation grade of each stage of magnetic separation can be improved, and on the other hand, the useless work consumed by the clay minerals in grinding can be reduced.
The magnetic gravity separation equipment configured in the embodiment is CJ350 type, namely, a magnetic gravity separator with stirring at the bottom of a cylinder, the diameter of the cylinder is 3.5m, the height of the cylinder is 3.0m, a bottom type magnetic disk is arranged, the magnetic field intensity is 1300MT, and the stirring speed is 7 r/min. The concentration of the feed pulp is controlled between 5 and 9 percent. The magnetic weight of the first section and the second section are respectively 3 devices, one device is used for purifying fine powder, 2 devices are used for collecting tail slurry, and the magnetic weight machine is arranged in the third section. The other beneficiation equipment in the flow is the same as in example 1.
The same feed rate (2 tonnes/hour feed rate) as in example one, with a 70T ore throughput as one analytical unit, example 2 gave the following test results: the tailing treatment capacity is 70 tons (converted into dry base), and the total output of the fine iron powder is 4.8T. The grade of the fine powder is 56.7 percent and the grade of the tailings is 3.8 percent through testing. The grade of the selected asbestos tailings is 8.5 percent, and the mineral separation recovery rate is 59.2 percent.
The experimental results show that the second embodiment has obviously improved the pure magnetic separation process compared with the first embodiment because of the addition of the medium magnetic agglomeration equipment, the concentrate grade and the recovery rate are improved, but the ore grinding efficiency is not high, and the comprehensive index is not ideal.
EXAMPLE III
The materials used in this example were the same as in examples one and two. The embodiment is different from the first and second embodiments, two devices for removing asbestos are additionally arranged on the basis of the flow of the second embodiment, as shown in fig. 3, one device is an alternating flow state machine, the other device is a cylindrical screen, one device of the alternating flow state machine is arranged on the flow after crushing and screening and is used for removing asbestos wool of dry tailings, the other two devices are arranged at the rear ends of the first section and the second section of grinding, and before magnetic separation, the alternating flow state machine is used for removing asbestos of a large number of asbestos bundles which are cleaved after grinding, so that the material environment of magnetic separation operation is improved.
The cotton removing equipment additionally arranged after three-stage ore grinding is a cylindrical screen, which mainly considers that after three-stage ore grinding, the cracked asbestos bundles are few, the fiber is extremely short, the technological requirements can be met by using a very fine screen (300 meshes), and meanwhile, the equipment cost is low and the energy consumption is low.
The magnetic gravity separation equipment is a magnetic gravity separator, as shown in fig. 4 and 5, the structure of the magnetic gravity separator comprises a feeding sleeve 5, ore pulp enters the bottom of a cylinder body through the feeding sleeve 5, and under the action of gravity, solid mineral particles flow around a magnetic disk 7 at the lower part of the sleeve. The magnetic disk 7 is a disk-shaped body which is internally provided with a permanent magnet and externally coated with a magnetic-permeable and wear-resistant material, and the diameter of the disk-shaped body is smaller than that of the inner cylinder of the cylinder body. The magnets in the disk 7 are arranged in a radial direction with magnetic poles of S-N-S-N, so that the magnetic field polarity extending in the radial direction S-N-S-N is also formed on the upper surface of the disk 7. The upper part of the magnetic disk 7 is provided with a stirring scraper 6 which is composed of four involute-shaped scrapers, and the part of the lower part of the stirring scraper 6, which is contacted with the magnetic disk 7, is a rubber plate to avoid the hard contact of the scraper and the magnetic disk 7 when the scraper rotates. The stirring scraper 6 is connected with the stirring shaft 4, and the stirring shaft 4 is fixed on the stirring bearing seat 2 at the upper part of the barrel and is driven by a driving device. Through adjusting the rotation rate of (mixing) shaft 4, just also adjusted the rotational speed of thick liquid stream in the barrel through stirring scraper 6, and then influenced the tangential velocity and the buoyancy of mineral particles in the ore pulp. The upper part of the cylinder body is provided with an overflow trough 3 and a tail water discharge hole 1, and tail water (containing tailings) overflowing from the upper part of the cylinder body is discharged through the tail water discharge hole 1. The water supply coil pipe 9 is arranged at the cone part of the cylinder body at the lower part of the magnetic disk 7, the size of the ascending water flow in the cylinder body is adjusted by adjusting the water supply size of the water supply coil pipe 9, and the buoyancy of the water is further adjusted. The lowermost end of the cone portion of the cylinder is fitted with a second closed discharger 8 for discharging heavy mineral particles (iron-containing mineral particles) falling from the edge of the magnetic disk 7, and also for preventing water from freely leaking.
During operation, ore pulp enters the cylinder of the water-filled magnetic weighing machine from the feeding sleeve 5, mineral particles flow onto the magnetic disc 7 through the lowest end of the feeding sleeve 5 under the action of self weight, the magnetic attraction force of the magnetic disc 7 causes the mineral particles containing magnet to be attracted on the magnetic disc 7, and the mineral particles without magnet gradually diffuse to the periphery of the magnetic disc 7. The magnetic disk 7 and the materials piled up at the feeding sleeve 5 are driven by the stirring scraper 6 which rotates continuously to move to the periphery of the magnetic disk 7 in time. The stirring scraper 6 is driven by a stirring shaft 4 fixed on the stirring bearing seat 2, and the upper part of the stirring shaft 4 is provided with a driving device. The materials on the magnetic disk 7 can move under the combined action of the magnetic attraction of the magnetic disk 7, the rotation of the stirring scraper 6 and the rotating water flow (caused by the rotation of the scraper); one is that the rotation of the stirring blade 6, which is designed in an involute shape, forces the mineral particles to move rapidly towards the periphery of the magnetic disk 7 (centrifugal force action). And secondly, the magnetic disk 7 designed to have S-N-S-N polarity can enable the moving mineral particles to continuously overturn under the combined action of magnetic attraction polarity change and forced driving of the stirring scraper 6, open the aggregate and the inclusion body and move towards the periphery of the magnetic disk 7 in an involute-shaped track. Thirdly, the ascending water flow driven by the stirring scraper 6 can make the light mineral particles (without magnet) which are continuously separated on the magnetic disk 7 due to overturning move upwards in a swirling manner, thereby implementing magnetic-heavy separation. Meanwhile, when mineral particles which continuously move towards the periphery of the cylinder body reach the edge of the magnetic disk 7, heavy mineral particles (minerals containing magnet) fall down through controlling the water supply quantity of the water supply coil pipe 9 at the lower part of the cylinder body, enter the cone part and are discharged by the second closed discharger 8 at the lowest part of the cylinder body. And the light mineral particles (containing no or few magnet minerals) reaching the edge of the magnetic disk 7 are driven by the constantly rising water flow around the magnetic disk 7 and the cylinder to move upwards and spirally rise along with the water flow, so that the material is reselected for the second time. The light mineral particles overflow from the uppermost part of the cylinder to the overflow groove 3 along with the spirally rising water flow and are discharged from the tail water discharge hole 1.
Besides the equipment for collecting asbestos and returning the asbestos-containing ore pulp to the tail water flow path of two-stage alternating flow state operation, a cylindrical sieve for collecting asbestos is additionally arranged on the main flow path of iron separation, so that the recovery rate of iron minerals is improved. The process of the embodiment designs a set of asbestos recovery and purification process, which consists of two sections of spraying type screening and purification and one section of rotational flow desanding. The first stage screening and purification is 4 parallel cylindrical screens, the second stage screening is 2 parallel cylindrical screens, the cyclone desanding is 4 groups of cyclone groups (phi 250), and the dewatering equipment is a filling type filter. The alternating current machine used in this example was an independently developed device, constructed as described in the material of the present application (see fig. 2), which handled 25 tons of ore per hour and had a bed size of 4.5m × 1.5m in length × width. In the embodiment, the solid-liquid ratio of the dry mineral except asbestos is controlled between 7 and 25. The concentration of the ore pulp in the ore pulp asbestos removing operation is controlled between 2 and 7. Because the equipment handling capacity is large, only one equipment is allocated to each section of the process.
The rotary spray type cylindrical sieve used in the embodiment is self-made equipment, the size of the sieve surface is phi 1.2m, the length is 4m, the rotating speed is 60r/min, and the treatment capacity per sieve is 4 tons (dry basis).
The concentration of the ore pulp obtained by each stage of magnetic separation in the embodiment is 10-7%.
The same feeding rate (2 tons/hour) as in the first and second examples, and taking 70T ore processing capacity as an analysis unit, the third example obtains the following test results:
the tailings treatment capacity is 70 tons (converted into dry base), the produced iron fine powder accounts for 8.5 tons, and the grade of the iron fine powder is 62.8 percent, the grade of the tailings is 2.3 percent, the grade of the selected asbestos tailings is 8.5 percent, and the ore dressing recovery rate of iron is 76 percent. In addition, 12.6 tons of recycled asbestos fiber (converted into dry basis) has the dust content of asbestos less than or equal to 5 percent and the sand content of less than or equal to 1.0 percent, which are superior to the national standard of products. The asbestos recovery exceeds the amount calculated as 3-3.5% of the cotton content of the tailings, which indicates that the tailings contain a large amount of non-cleaved asbestos wool of not less than 2%.
Due to timely asbestos removal, the iron separation process is smooth and efficient, the ore grinding efficiency is obviously improved, the abrasion is reduced, and the ore entering amount is increased. Through statistics, the energy consumption of the iron production line is reduced by 2% compared with the embodiment I and the embodiment II, and the treatment capacity and the production efficiency of the whole production system are obviously improved.
In the beneficiation process, the overflow product at the upper part after the gravity separation by the alternating flow state machine is a mixed product of asbestos and dust without iron sand, and washing, dust removal and sand removal operations are required, and the process is considered in the process. The overflow product after the gravity separation of the fluid cross-flow type separator is a water slurry mixture containing asbestos and dust, and the concentration of the slurry is between 5 and 7 percent. Because the asbestos dust is formed by mixing fine serpentine powder and fine particles of ground covering loess, talc, montmorillonite and the like, the minerals are mixed with water into ore pulp and have high viscosity. The phenomena of difficult separation of fiber and dust, screen pasting and screen sticking are shown in the screening operation; rotary shower-type cylindrical screens are preferred.
The concentration of the ore pulp entering the screening operation is controlled to be 5-7%, and the selected materials are fully mixed with water, so that the ore pulp is uniform. The equipment for screening, purifying and classifying asbestos and dust adopts a rotary spraying type cylindrical sieve. A magnetic re-dressing machine for removing clay minerals (or collecting weak magnetic minerals after magnetic separation to increase the recovery rate of iron) features that a medium-magnetic agglomerating apparatus with stirring function, such as medium-magnetic agglomerating magnetic separator and medium-magnetic agglomerator, is used. The concentration of the ore pulp entering the magnetic weighing machine is 10-30%. The apparatus used for grinding the ore is a ball mill, either overflow or grate type. The grading equipment of the second section and the third section is a common swirler group, the diameter of the swirler before the second section grinding is phi 70-350mm, and the diameter of the swirler before the third section grinding is phi 20-250 mm. And the grading equipment after the first-stage ball milling adopts a spiral grader.
The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (4)

1. A mineral processing technology for recovering iron from asbestos tailings is characterized in that: the method comprises the following steps:
step one; pretreating, crushing asbestos tailings after primary screening, screening again after crushing, adding water into the materials with the granularity of less than 10mm after secondary screening, and feeding the materials with the granularity of more than 10mm back to the next treatment device for continuous crushing;
step two; grinding the ore for the first time; adopting a grid ball mill with phi 2.2 multiplied by 4.5m and a double-helix classifier with the model of phi 1.2 multiplied by 12m, controlling the concentration of classifying ore pulp of the material to be 7-25% and the concentration of ore pulp of ball milling and grinding to be 75-85%;
step three; first-stage magnetic separation; a barrel-type permanent magnetic separator is adopted to absorb iron-containing minerals in the material and send the iron-containing minerals into the next process; discharging the materials which are not absorbed into a tailing pond as tailings;
step four; cyclone classification; classifying the iron-containing minerals by adopting a polyurethane cyclone, concentrating the materials with the particle sizes of more than 250-plus-325 meshes by cyclone, then entering a second-stage ore grinding process, and directly entering a second-stage magnetic separation process for the materials with the particle sizes of less than 250-plus-325 meshes;
step five: repeating the second, third and fourth steps until the iron-containing minerals are subjected to three-stage magnetic separation, and then dehydrating through a disc type vacuum filter to obtain an iron concentrate powder product;
a magnetic gravity separation step is also included between the magnetic separation and the cyclone classification; the magnetic-gravity separation adopts a magnetic-gravity separator, the diameter of the magnetic-gravity separator is 3.5m, the height of the magnetic-gravity separator is 3.0m, the magnetic field intensity of a bottom magnetic disk is 1300MT, and the stirring speed is 7 r/min; in the first step, the material after secondary screening also comprises a step of removing asbestos, wherein an alternating flow state machine is adopted in the step; in the second step and the fifth step, the materials after the first-stage ore grinding and the second-stage ore grinding are subjected to asbestos removal operation by adopting an alternating flow state machine; the materials after the three-section ore grinding are subjected to final asbestos removing operation by adopting a cylindrical sieve; a cylindrical screen is arranged on a tail water flow path of the alternating flow state machine after the second-stage ore grinding, and is used for collecting asbestos and returning iron-containing ore pulp; the method also comprises an asbestos recovery step, which is used for recovering the asbestos removed after the screening of the alternating flow state machine and the cylinder; firstly, 4 parallel cylindrical sieves are adopted to carry out spraying type first-stage screening purification; secondly, two parallel cylindrical sieves are adopted for spraying type two-stage screening and purification, then one 4 groups of cyclone units are adopted for cyclone desanding, and finally a filling type filter is adopted for dehydration.
2. The beneficiation process to recover iron from asbestos tailings according to claim 1, wherein: the magnetic gravity separator comprises a cylinder body, wherein the side wall of the upper end of the cylinder body is respectively connected with a tail water discharge hole and an overflow groove, a vertical feeding sleeve and a stirring shaft are arranged in the cylinder body, and the top end of the stirring shaft is arranged at the top of the cylinder body through a stirring shaft bearing seat; the stirring shaft is symmetrically provided with a plurality of stirring scrapers, the bottom of the barrel is provided with a magnetic disk, a conical part is arranged below the magnetic disk, the conical part is hermetically connected with the bottom of the barrel, a water supply pipe disc is arranged above the conical part, and the bottom of the conical part is provided with a second closed discharger.
3. The beneficiation process to recover iron from asbestos tailings according to claim 2, wherein: the magnetic disc is of a disc-shaped body structure, the interior of the magnetic disc is provided with a permanent magnet, the exterior of the magnetic disc is coated with a magnetic-permeable and wear-resistant material, and the diameter of the magnetic disc is smaller than that of the inner cylinder of the cylinder; the permanent magnets are arranged in the magnetic disk along the radial direction according to the magnetic poles of S-N-S-N.
4. The beneficiation process to recover iron from asbestos tailings according to claim 2, wherein: four stirring scrapers are symmetrically arranged on the stirring shaft, and are of involute structures respectively.
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CN110947493A (en) * 2019-11-20 2020-04-03 郑州中科新兴产业技术研究院 Preparation method of ultra-pure fine iron powder

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