Graded magnetic separation washing engineering sand making system and process

Abstract

The invention relates to the technical field of gravel production, in particular to a graded magnetic separation washing engineering sand making system and process, the graded magnetic separation washing engineering sand making system comprises a joint dispatching subsystem, a feeding device, a sand making device, a wet screening device, a first sand washing device, a magnetic separation device, a second sand washing device and a post-processing subsystem, and the joint dispatching subsystem is used for achieving production and transportation regulation and control of all the devices; the sand making equipment is used for producing artificial sand, the wet screening equipment is used for screening the artificial sand and provided with a screen A and a screen B located below the screen A, the aperture of the screen B is smaller than that of the screen A, an oversize outlet of the screen A is connected with a feeding port of the sand making machine, and a feeding port of the first sand washing equipment is connected with an oversize outlet of the screen B; a feeding hole of the magnetic separation equipment is connected with an undersize outlet of the screen B, a feeding hole of the second sand washing equipment is connected with a concentrate outlet of the magnetic separation equipment, and a feeding hole of the post-treatment subsystem is connected with a tailing outlet of the magnetic separation equipment. The method has the advantages of being high in practical operability, good in economical efficiency and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of sand and gravel production, and in particular to a graded magnetic separation and water washing engineering sand making system and process. Background Art

[0002] As a controllable and adjustable clean energy base load, hydropower is the foundation for establishing a new power system. It is of great significance to build a clean, low-carbon, safe and efficient new energy system and to ensure national energy security. The sand and gravel aggregates needed in the construction of hydropower projects are usually obtained by local materials. Natural rocks are mined in suitable material yards near the hub area, and a series of crushing and shaping processes are used to make finished sand and gravel aggregates for hydropower station construction. In hydropower projects, concrete dams have strict requirements on the dam foundation. Generally, the dam site needs to be selected in the bedrock section with good geological conditions, such as granite dam foundation (the bedrock of the dam foundations of the Three Gorges, Yebatan, and Mengdigou hydropower stations is granite).

[0003] The problem of high mica content in sand made from natural rocks such as granite exists. Mica is a rock-forming mineral with a layered structure and a glassy luster. During the mechanical crushing and sand-making process of granite, some of the mica in it will be stripped out and exist in the sand in a free state in the form of flakes. However, the free mica in the form of flakes has low strength, a smooth surface, and poor bonding with cement, which has an adverse effect on the compression, tension, frost resistance, and durability of concrete. The "Specifications for Construction of Hydraulic Concrete" (DL / T5144-2015) requires that the mica content in sand should not exceed 2%. Therefore, when the mica content exceeds the standard, appropriate methods must be used in the project to reduce the mica content in the machine-made sand.

[0004] However, there is currently no mature method in China that can economically and effectively reduce the mica content in machine-made sand. Conventional methods include air separation, water washing and magnetic separation. Air separation is usually used in the mica manufacturing industry, such as the mica particle air separation system proposed in CN104772280A, which uses air as a medium to separate mica particles of different sizes and shapes. However, in the sand making process, the air separation method has the disadvantages of large dust pollution, difficulty in high-capacity production, and the actual effect of reducing mica is not obvious; water washing methods such as the wet method for removing mica from machine-made sand proposed in CN116037295A and the method for removing biotite in the process of machine-made sand proposed in CN116803538A are also not widely used. The method, a two-stage flotation mica removal process for machine-made sand proposed in CN113546752A, etc., by adjusting the ratio of water to raw ore, and taking advantage of the principle that the solid particles in the machine-made sand have different sizes and specific gravities, and thus different sedimentation speeds in the liquid, the mica is washed out. However, when washing mica out of the water washing method, the fine particles in the sand will also be washed out, making the fineness modulus of the finished sand exceed the standard; the magnetic separation method is mainly used to remove biotite in machine-made sand. Biotite contains a certain component (usually about 20%) of Fe2O3, which can be electromagnetically separated. Adsorption and removal, such as the sorting system for removing biotite from artificial sand proposed in CN106733176A, which installs magnetic poles on the outside of the vertical conduit and uses the artificial sand free fall to continuously apply lateral horizontal magnetic force to it during the falling process, so that the biotite therein produces continuous horizontal acceleration, thereby changing its falling trajectory, which is different from the trajectory of other remaining granite artificial sand, and finally achieves the purpose of distinguishing biotite gravel, that is, free biotite, from the remaining artificial sand; CN113546749A proposed a machine-made sand magnetic separation and flotation combined mica removal process, which adds various chemical reagents to the washed sand after magnetic separation, and then flotation, concentration, filtration, dehydration and other processes to obtain finished sand, which has complex processes and low practicality on the construction site; CN113769888A proposed a machine-made sand mica removal magnetic separation system, which installs a magnetic system component under the belt of the belt conveyor to adsorb the mica in the machine-made sand on the belt. Practice has proved that when the production capacity is large, the magnet cannot adsorb the biotite on the upper part of the machine-made sand, and the amount of mica that can be removed by this method is limited.

[0005] The graded magnetic separation process was explored in the paper "Application of Magnetic Separation Technology in the Production of Artificial Sand in the Three Gorges Project" published in 2006. The author screened the raw ore sand into sand with a particle size of 2-5mm and less than 2mm, and used different dry magnetic separators to perform magnetic separation on them. The research results showed that the separation effect of the coarse particle size grade was better than that of the fine particle size grade, but the reduction of free mica would cause a sand rate loss of 31.19%; the wet induction roller graded magnetic separation effect was better than dry magnetic separation, but it would still cause a large loss of minerals in the raw sand and increase the sand fineness modulus.

[0006] Based on this, how to economically and effectively reduce the mica content in machine-made sand is a technical problem that urgently needs to be solved. Summary of the invention

[0007] The purpose of the present invention is to provide a graded magnetic separation and water washing engineering sand making system and process, which screens artificial sand with a particle size of less than 5 mm into fine sand enriched with free mica and coarse sand without free mica, and obtains non-magnetic sand and mica after magnetic separation of the fine sand alone, and then mixes the coarse sand back into the non-magnetic sand according to a preset grading ratio to obtain finished sand with a mica content that meets the engineering requirements, so that the sand loss rate is only about 10%, and the fineness modulus and grading of the finished sand after mixing with the coarse sand meet the specification requirements, and has the advantages of strong practicality and good economy. In addition, the magnetic separation tailings are sent to a post-processing subsystem for separation and treatment, and mica is also obtained as a by-product. The whole process is wet-processed, so it also has the advantage of being dust-free and environmentally friendly, so as to solve the technical problem of how to economically and effectively reduce the mica content in machine-made sand.

[0008] The present invention is implemented through the following technical solutions: a graded magnetic separation and water washing engineering sand making system, comprising a joint adjustment subsystem, a feeding device, a sand making device, a wet screening device, a first sand washing device, a magnetic separation device, a second sand washing device and a post-processing subsystem, wherein the joint adjustment subsystem is respectively connected to the feeding device, the sand making device, the wet screening device, the first sand washing device, the magnetic separation device and the second sand washing device for realizing the production and transportation control of each device;

[0009] Among them, the sand making equipment is arranged downstream of the feeding equipment and is used to produce artificial sand. The wet screening equipment is arranged downstream of the sand making equipment and is used to screen the artificial sand. The wet screening equipment has a screen A and a screen B. The screen A is arranged above the screen B. The aperture of the screen A is larger than the aperture of the screen B. The upper screen outlet of the screen A is connected to the feed inlet of the sand making machine. The magnetic separation equipment and the first sand washing equipment are both arranged downstream of the wet screening equipment. The feed inlet of the first sand washing equipment is connected to the upper screen outlet of the screen B, and the feed inlet of the magnetic separation equipment is connected to the lower screen outlet of the screen B. The second sand washing equipment and the post-processing subsystem are both arranged downstream of the magnetic separation equipment. The feed inlet of the second sand washing equipment is connected to the concentrate outlet of the magnetic separation equipment, and the feed inlet of the post-processing subsystem is connected to the tailings outlet of the magnetic separation equipment.

[0010] According to a preferred embodiment, the aperture of the sieve A is 5 mm, and the aperture of the sieve B is 3 mm.

[0011] According to a preferred embodiment, the sand making equipment is a vertical shaft sand making machine.

[0012] According to a preferred embodiment, the wet screening equipment is a linear vibrating screen.

[0013] According to a preferred embodiment, the magnetic separation equipment is provided with a plurality of magnetic separators, and the plurality of magnetic separators are arranged in series and / or in parallel.

[0014] According to a preferred embodiment, the magnetic separator is a rotary high gradient magnetic separator.

[0015] According to a preferred embodiment, the first sand washing equipment comprises a first sand washing machine, the feed inlet of the first sand washing machine is connected to the outlet on the screen of the screen B, and the discharge port of the first sand washing machine is connected to the coarse sand bin;

[0016] The second sand washing equipment includes a second sand washing machine, an inlet of the second sand washing machine is connected to the concentrate outlet of the magnetic separator or the second discharge port of the collecting hopper, and the discharge port of the second sand washing machine is connected to the fine sand bin.

[0017] According to a preferred embodiment, the first sand washing machine and / or the second sand washing machine is a bucket wheel sand washing machine.

[0018] According to a preferred embodiment, the post-processing subsystem includes a magnetic sand sedimentation and separation tank and a sewage treatment device. The feed inlet of the magnetic sand sedimentation and separation tank is connected to the tailings outlet of the magnetic separation equipment, and the sewage outlet of the magnetic sand is connected to the sewage inlet of the sewage treatment equipment through a sewage conveying pipe. A sewage pump is provided on the sewage conveying pipe.

[0019] The present invention also provides a graded magnetic separation and water washing engineering sand making process, which uses the graded magnetic separation and water washing engineering sand making system as described above, and includes the following steps:

[0020] S1. The sand making equipment is operated to produce artificial sand, and the artificial sand is sent to the wet screening equipment;

[0021] S2. The wet screening equipment is operated to classify the artificial sand according to the preset particle size requirements, returning the ore with a particle size greater than 5 mm to the feeding equipment, sending the artificial sand with a particle size of 5 mm to 3 mm to the first sand washing equipment, and sending the artificial sand with a particle size less than 3 mm to the magnetic separation equipment;

[0022] S3. For the two levels of artificial sand, the artificial sand of 5mm to 3mm is washed by the first sand washing equipment to obtain coarse sand, and the artificial sand of 3mm is magnetically separated by a magnetic separator to obtain fine concentrate, and the fine concentrate is sent to the second sand washing equipment for washing to obtain fine sand, and the magnetic separation tailings are sent to the post-processing subsystem for separation and treatment to obtain mica as a by-product.

[0023] S4. The dehydrated coarse sand is mixed back into the fine sand according to a preset gradation ratio to obtain finished sand.

[0024] The technical scheme of a graded magnetic separation and water washing engineering sand making system and process provided by the present invention has at least the following advantages and beneficial effects: (1) the present invention screens artificial sand with a particle size of less than 5 mm into fine sand with a particle size of less than 3 mm enriched with free mica and coarse sand with a particle size of 3 mm to 5 mm and no free mica, and then magnetically separates the fine sand to obtain non-magnetic sand and mica, and then mixes the coarse sand back into the non-magnetic sand according to a preset grading ratio to obtain finished sand with a mica content that meets the engineering requirements, so that the sand loss rate is only about 10%, and the fineness modulus and grading of the finished sand after mixing with the coarse sand meet the requirements of the specification, and has the advantages of strong practicality and good economy; (2) the magnetic separation tailings are sent to the post-processing subsystem for separation and treatment, and mica as a by-product is obtained. The whole process is wet-processed, so it also has the advantages of low dust emission and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the layout of the graded magnetic separation and water washing engineering sand making system provided in Example 1 of the present invention;

[0026] Figure 2 A top view of a collecting hopper provided in Example 5 of the present invention;

[0027] Figure 3 A side view of a collecting hopper provided in Example 5 of the present invention;

[0028] Figure 4 A schematic diagram of the serial arrangement of magnetic separation equipment provided in Example 4 of the present invention;

[0029] Figure 5 A schematic diagram of the parallel arrangement of magnetic separation equipment provided in Example 4 of the present invention;

[0030] Figure 6 A schematic diagram of the series-parallel arrangement of magnetic separation equipment provided in Example 4 of the present invention;

[0031] Figure 7 A schematic diagram showing the comparison of the gradation of coarse sand before and after the reincorporation of the coarse sand provided in Example 8 of the present invention;

[0032] Figure numerals: 1-feeding equipment, 2-sand making equipment, 3-belt conveyor, 4-wet screening equipment, 5-screen A, 6-screen B, 7-collecting hopper, 8-guide trough, 9-magnetic separation equipment, 10-first sand washing equipment, 11-second sand washing equipment, 12-fine sand bin, 13-coarse sand bin, 14-joint adjustment subsystem, 15-magnetic sand sedimentation and separation tank, 16-sewage pump, 17-sewage treatment equipment, 18-fine sand recovery equipment, 19-concrete mixing plant, 20-first discharge port, 21-second discharge port, 22-blocking grille. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] Example 1

[0035] See also Figure 1 As shown, this embodiment provides a graded magnetic separation and water washing engineering sand making system, including a joint adjustment subsystem 14, a feeding device 1, a sand making device 2, a wet screening device 4, a first sand washing device 10, a magnetic separation device 9, a second sand washing device 11 and a post-processing subsystem; wherein the joint adjustment subsystem 14 is respectively communicated with the feeding device 1, the sand making device 2, the wet screening device 4, the first sand washing device 10, the magnetic separation device 9 and the second sand washing device 11, so as to realize the production and transportation regulation of each equipment.

[0036] The sand making equipment 2 is arranged downstream of the feeding equipment 1 and is used to produce artificial sand. In this embodiment, the sand making equipment 2 is used to produce artificial sand with a particle size of less than 5 mm, and a belt conveyor 3 or a guide trough 8 is used to transport the artificial sand to the wet screening equipment 4 arranged downstream thereof. The wet screening equipment 4 is used to screen the artificial sand.

[0037] In this embodiment, the wet screening equipment 4 is provided with a double-layer screen, namely, screen A5 and screen B6. The screen A is arranged above the screen B6. The aperture of the screen A5 is larger than the aperture of the screen B6. The aperture of the screen A5 is preferably 5 mm, and the aperture of the screen B6 is preferably 3 mm. Through the screen A5, the artificial sand can be screened into rice stone with a particle size greater than or equal to 5 mm and sand with a particle size less than 5 mm.

[0038] Furthermore, the upper screen outlet of the screen A5 is connected to the feed port of the sand making machine to return the stone with a particle size greater than or equal to 5 mm to the sand making equipment 2 for crushing again; the magnetic separation equipment 9 and the first sand washing equipment 10 are both arranged downstream of the wet screening equipment 4, and the feed port of the first sand washing equipment 10 is connected to the upper screen outlet of the screen B6 to send artificial sand with a particle size of 5 mm to 3 mm to the first sand washing equipment 10 for washing to obtain coarse sand; the feed port of the magnetic separation equipment 9 is connected to the lower screen outlet of the screen B6 to send artificial sand with a particle size less than 3 mm to the magnetic separation equipment 9 for magnetic separation to obtain magnetic sand enriched with free mica (hereinafter referred to as tailings) and non-magnetic sand with a small free mica content (hereinafter referred to as fine concentrate).

[0039] The second sand washing equipment 11 and the post-processing subsystem are both arranged downstream of the magnetic separation equipment 9. The feed port of the second sand washing equipment 11 is connected to the concentrate outlet of the magnetic separation equipment 9, so as to send the fine concentrate to the second sand washing equipment 11 for washing and obtaining fine sand. It should be noted that by mixing the dehydrated coarse sand back into the fine sand according to a preset grading ratio, finished sand with a mica content that meets the engineering requirements can be obtained. The feed port of the post-processing subsystem is connected to the tailings outlet of the magnetic separation equipment 9, so as to send the tailings to the post-processing subsystem for separation and treatment to obtain mica as a by-product.

[0040] Specifically, the present invention screens artificial sand with a particle size of less than 5 mm into fine sand with a particle size of less than 3 mm enriched with free mica and coarse sand with a particle size of 3 mm to 5 mm and no free mica, and then magnetically separates the fine sand to obtain non-magnetic sand and mica. Subsequently, the coarse sand is mixed back into the non-magnetic sand according to a preset grading ratio to obtain finished sand with a mica content that meets engineering requirements, which can be transported to a concrete mixing plant 19 for mixed use. In this way, the sand loss rate is only about 10%, and the fineness modulus and gradation of the finished sand after the coarse sand is mixed back meet the requirements of the specification, and it has the advantages of strong practicality and good economy. In addition, the magnetically separated tailings are sent to a post-processing subsystem for separation and treatment, and mica as a by-product is obtained. The whole process is wet-processed, so it also has the advantages of being dust-free and environmentally friendly.

[0041] Example 2

[0042] This embodiment is based on the technical solution provided in Example 1, and further describes the sand making equipment 2:

[0043] In some embodiments, the sand making equipment 2 can be selected as a vertical shaft sand making machine, a double-roller sand making machine, a composite sand making machine, an impact sand making machine, a cone crusher or a hammer crusher, etc. The present embodiment preferably uses a vertical shaft sand making machine.

[0044] Specifically, compared with the other sand making equipment 2 mentioned above, the vertical shaft sand making machine has at least the following advantages:

[0045] (1) Excellent particle shape. The vertical shaft sand making machine adopts the crushing principle of stone hitting stone and stone hitting iron. The rock is subjected to high-speed impact and multiple collisions in the crushing chamber, which can make the rock form a relatively regular cubic shape during the mutual impact and friction. The 5mm artificial sand produced has good particle shape and low content of needle-like particles, which can better meet the engineering requirements of high-quality concrete and other projects with high requirements on sand particle shape. (2) High crushing efficiency. The impeller and distributor design of the vertical shaft sand making machine enables the rock to be evenly distributed in the crushing chamber and can achieve multiple impact crushing of the material. When producing 5mm artificial sand, its crushing efficiency is high, and it can effectively process a large amount of rock, with a high output per unit time.

[0046] In summary, the use of vertical shaft sand making machine to produce 5mm artificial sand has the advantages of excellent particle shape and high crushing efficiency.

[0047] Example 3

[0048] This embodiment is based on the technical solution provided in Example 1, and further describes the wet screening device 4:

[0049] In some embodiments, the wet screening equipment 4 may be a linear vibrating screen, a circular vibrating screen, a high-frequency vibrating screen, a banana screen or a shaking screen, etc. In this embodiment, a linear vibrating screen is preferred.

[0050] Specifically, compared with the other wet screening equipment 4 mentioned above, the use of a linear vibrating screen has at least the following advantages:

[0051] (1) High screening accuracy. The linear vibrating screen uses vibration motor excitation as the vibration power source to throw the material on the screen and move forward in a straight line. This linear motion makes the movement trajectory of the material on the screen surface more stable, and can be more accurately graded according to the size of the screen hole, thereby improving the screening accuracy and effectively distinguishing between coarse sand of 3mm to 5mm and fine sand less than 3mm.

[0052] In summary, in the scenario of screening coarse sand of 3mm to 5mm and fine sand less than 3mm, the use of linear vibrating screen has the advantage of high screening accuracy.

[0053] Example 4

[0054] This embodiment is based on the technical solution provided in Example 1, and further describes the magnetic separation device 9:

[0055] In some embodiments, the magnetic separation device 9 is provided with a plurality of magnetic separators, and the plurality of magnetic separators are arranged in series and / or in parallel.

[0056] See also Figure 4 As shown, three magnetic separators are arranged in series. In actual operation, after the sand-water mixture is transported to magnetic separator No. 1 through the guide trough 8, the non-magnetic sand magnetically selected by magnetic separator No. 1 enters magnetic separator No. 2 through the guide trough 8 for further magnetic selection, and the non-magnetic sand magnetically selected by magnetic separator No. 2 enters magnetic separator No. 3 through the guide trough 8 for further magnetic selection, and the non-magnetic sand magnetically selected by magnetic separator No. 3 is transported to the second sand washing equipment 11 through the guide trough 8, and the magnetic sand magnetically selected by magnetic separators No. 1 to 3 is discharged to the post-processing subsystem respectively.

[0057] See also Figure 5As shown, three magnetic separators are arranged in parallel, and wet screening equipment 4 is configured for each of the three magnetic separators. The under-screen outlet of the screen B6 in each wet screening equipment 4 is connected to the feed port of the corresponding magnetic separator. The sand-water mixture output from the under-screen outlet of the screen B6 is transported to the corresponding magnetic separator through the guide trough 8. The magnetic sand magnetically separated is discharged to the post-processing subsystem, and the non-magnetic sand is transported to the second sand washing equipment 11.

[0058] See also Figure 6 As shown, there are two groups of magnetic separators, each group includes three magnetic separators arranged in series, and a wet screening device 4 is respectively configured for each group of magnetic separators, the under-screen outlet of the screen B6 in each wet screening device 4 is connected to the feed port of the No. 1 magnetic separator in the corresponding group, and the sand-water mixture output from the under-screen outlet of the screen B6 is transported to the corresponding No. 1 magnetic separator through the guide trough 8, and the non-magnetic sand magnetically selected by the No. 1 magnetic separator enters the No. 2 magnetic separator through the guide trough 8, and the non-magnetic sand magnetically selected by the No. 2 magnetic separator enters the No. 3 magnetic separator through the guide trough 8 for further magnetic selection, and the non-magnetic sand magnetically selected by the No. 3 magnetic separator is transported to the second sand washing equipment 11 through the guide trough 8, and the magnetic sand magnetically selected by the No. 1 to No. 3 magnetic separators is discharged to the post-processing subsystem respectively.

[0059] Specifically, under the series operating condition, the single-machine production capacity of several magnetic separators of the magnetic separation equipment 9 should be greater than the fine sand production capacity of the sand making system; under the parallel operating condition, the total production capacity of several magnetic separators of the magnetic separation equipment 9 should be greater than the fine sand production capacity of the sand making system; under the series-parallel operating condition, it is ensured that the value of the single-machine production capacity on the parallel line multiplied by the number of parallel lines is greater than the fine sand production capacity of the sand making system.

[0060] Furthermore, the magnetic separation device 9 can be selected as a rotary high gradient magnetic separator, a dry magnetic separator, a wet magnetic separator, a magnetic separation column or a magnetic dehydration tank, etc. In this embodiment, a rotary high gradient magnetic separator is preferred.

[0061] Specifically, compared with the other magnetic separation equipment 9 mentioned above, the use of a rotary high gradient magnetic separator has at least the following advantages:

[0062] (1) Good magnetic separation effect. The magnetic system of the rotary high-gradient magnetic separator is made of high-quality ferrite material or a composite with rare earth magnet steel, which can generate a high magnetic field strength. The average magnetic induction intensity of the drum surface can reach 100-600mT. In this embodiment, the magnetic flux of the magnetic separator is set to 1T during magnetic separation. For fine sand less than 3mm, a stronger magnetic field can more effectively attract the magnetic particles therein, and even weakly magnetic minerals can be better captured, thereby improving the magnetic separation effect; (2) The grade and recovery rate of the concentrate are higher. The rotary high-gradient magnetic separator has a specially designed magnetic medium and magnetic circuit structure. The rotary high-gradient magnetic separator can generate a very high magnetic field gradient. The high magnetic field gradient makes the magnetic force acting on the magnetic particles greater, which can overcome the fluid resistance and gravity of the fine sand particles, so that the lower limit of the separation particle size can be reduced to 1μm. This means that for fine sand less than 3mm, it can more accurately separate the fine magnetic particles therein, thereby improving the grade and recovery rate of the concentrate.

[0063] In summary, when magnetically separating fine sand smaller than 3 mm, the use of a rotary high-gradient magnetic separator has the advantages of higher magnetic separation effect, higher concentrate grade and recovery rate.

[0064] Example 5

[0065] This embodiment is based on the technical solution provided in any one of Embodiments 1 to 4, and further describes the wet screening device 4:

[0066] In some embodiments, the wet screening device 4 further includes a collecting hopper 7, which is arranged below the screen B6; see Figure 2 and Figure 3 As shown, the collecting hopper 7 has a first discharge port 20 and a second discharge port 21. The first discharge port 20 of the collecting hopper 7 is connected to the feed port of the magnetic separator to deliver artificial sand with a particle size less than 3 mm to the magnetic separator for magnetic separation.

[0067] The second discharge port 21 of the collecting hopper 7 is connected to the feed port of the second sand washing equipment 11. When magnetic separation is not required, artificial sand with a particle size of less than 3 mm can be directly sent to the second sand washing equipment 11 for washing through the second discharge port 21; wherein, the first discharge port 20 and the second discharge port 21 are both provided with a blocking grille 22, and the conduction between the first discharge port 20 and the second discharge port 21 is controlled by the blocking grille 22. When magnetic separation is not required, by opening the blocking grille 22 on the first discharge port 20 and closing the blocking grille 22 on the second discharge port 21, artificial sand with a particle size of less than 3 mm can be sent to the second sand washing equipment 11 through the first discharge port 20; conversely, when magnetic separation is required, by opening the blocking grille 22 on the second discharge port 21 and closing the blocking grille 22 on the first discharge port 20, artificial sand with a particle size of less than 3 mm can be sent to the feed port of the magnetic separation equipment 9 through the second discharge port 21 and the guide groove 8 located on the outlet side of the second discharge port 21. Specifically, by providing two discharge ports of the collecting hopper 7, the application scope of the system can be improved to meet the production needs of finished sand with different mica contents.

[0068] Example 6

[0069] This embodiment further describes the sand washing equipment based on the technical solution provided in Example 5:

[0070] In some embodiments, the first sand washing equipment 10 includes a first sand washing machine, the feed port of the first sand washing machine is connected to the screen outlet of the screen B6, and the discharge port of the first sand washing machine is connected to the coarse sand bin 13; the second sand washing equipment 11 includes a second sand washing machine, the feed port of the second sand washing machine is connected to the concentrate outlet of the magnetic separator or the second discharge port 21 of the collecting hopper 7, and the discharge port of the second sand washing machine is connected to the fine sand bin 12.

[0071] Furthermore, the system also includes a fine sand recovery device 18, which is arranged downstream of the second sand washing machine, and is used to collect wastewater discharged from the second sand washing machine and recover fine particles therefrom. The recovered fine particles are transported to the belt conveyor 3 arranged at the discharge port of the second sand washing machine, and are sent to the fine sand bin 12 for storage together with the fine sand output by the second sand washing machine; in addition, the wastewater discharged from the sand washing recovery device is sent to the post-processing subsystem for treatment.

[0072] In some embodiments, the sand washing machine may be a bucket wheel sand washing machine, a spiral sand washing machine, a drum sand washing machine or a vibrating sand washing machine. In this embodiment, preferably, the first sand washing machine and / or the second sand washing machine is a bucket wheel sand washing machine.

[0073] Specifically, compared with the other sand washing machines mentioned above, the bucket wheel sand washing machine has at least the following advantages:

[0074] (1) High degree of cleanliness. When working, driven by the impeller, the sand and gravel grind against each other, which can remove impurities covering the surface of the sand and gravel, and at the same time destroy the water vapor layer covering the sand particles. Coupled with the strong water flow, it can effectively complete the cleaning and impurity removal functions, so that the cleanliness of the finished sand is relatively high. Whether it is coarse sand or fine sand, it can get a good cleaning effect. The washed sand has low mud content and can meet the high requirements of the construction industry for the cleanliness of sand materials; (2) Less loss of fine sand. The bucket wheel sand washing machine has a reasonable structural design and water flow control. It can effectively reduce the loss of fine sand during the washing process and can control the loss rate of fine sand at a low level, making the grading of the finished sand more reasonable, which not only ensures the quality of coarse sand, but also can retain fine sand to the greatest extent, thereby improving the comprehensive utilization rate of sand materials.

[0075] In summary, when washing coarse sand of 5mm to 3mm and fine sand less than 3mm, the bucket wheel sand washing machine has the advantages of high cleaning degree and less sand loss.

[0076] Example 7

[0077] This embodiment is based on the technical solution provided in Example 1, and further describes the post-processing subsystem:

[0078] In some embodiments, the post-processing subsystem includes a magnetic sand sedimentation separation tank 15 and a sewage treatment device 17. The feed port of the magnetic sand sedimentation separation tank 15 is connected to the tailings outlet of the magnetic separation device 9, and is used to process the waste liquid tailings from the magnetic separation device 9 and separate the mica in the waste liquid tailings by sedimentation.

[0079] Furthermore, the sewage outlet of the magnetic sand sedimentation and separation tank 15 is connected to the sewage inlet of the sewage treatment equipment 17 through a sewage conveying pipe. The sewage conveying pipe is provided with a sewage pump 16. The sewage separated in the magnetic sand sedimentation and separation tank 15 is pumped to the external sewage treatment equipment 17 for treatment through the sewage pump 16. Therefore, the sand making system provided in this embodiment also has the advantage of being environmentally friendly.

[0080] Example 8

[0081] This embodiment is based on the technical solution provided in any one of Embodiments 1 to 7 to further illustrate the sand making process:

[0082] A graded magnetic separation and water washing engineering sand making process, using the graded magnetic separation and water washing engineering sand making system as described in any one of Examples 1 to 7, comprises the following steps:

[0083] S1, the sand making equipment 2 is operated to produce artificial sand, and the artificial sand is sent to the wet screening equipment 4;

[0084] S2, the wet screening equipment 4 is running to classify the artificial sand according to the preset particle size requirements, the ore with a particle size greater than 5 mm is returned to the sand making equipment 2 for crushing again, the artificial sand with a particle size of 5 mm to 3 mm is sent to the first sand washing equipment 10, and the artificial sand with a particle size less than 3 mm is sent to the magnetic separation equipment 9;

[0085] S3. For artificial sands of two coarse and fine grades, the artificial sand of 5 mm to 3 mm is washed by the first sand washing equipment 10 to obtain coarse sand, and the artificial sand of 3 mm is magnetically separated by a magnetic separator to obtain fine concentrate, and the fine concentrate is sent to the second sand washing equipment 11 for washing to obtain fine sand, and the magnetic separation tailings are sent to the post-processing subsystem for separation and treatment to obtain mica as a by-product.

[0086] S4. Add the dehydrated coarse sand back into the fine sand according to the preset gradation ratio to obtain finished sand. For the gradation curve after back mixing, refer to Figure 7 , where lines A to E are the lower limit, upper limit, artificial sand in normal production, artificial sand after removing mica with particle size below 3mm, and artificial sand after re-mixing coarse sand.

[0087] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A graded magnetic separation and water washing engineering sand making system, characterized in that: The invention comprises a joint adjustment subsystem (14), a feeding device (1), a sand making device (2), a wet screening device (4), a first sand washing device (10), a magnetic separation device (9), a second sand washing device (11) and a post-processing subsystem, wherein the joint adjustment subsystem (14) is respectively connected to the feeding device (1), the sand making device (2), the wet screening device (4), the first sand washing device (10), the magnetic separation device (9) and the second sand washing device (11) in communication with each other, and is used to realize the production and transportation control of each device; The sand making device (2) is arranged downstream of the feeding device (1) and is used to produce artificial sand. The wet screening device (4) is arranged downstream of the sand making device (2) and is used to screen the artificial sand. The wet screening device (4) comprises a screen A (5) and a screen B (6). The screen A is arranged above the screen B (6). The aperture of the screen A (5) is larger than the aperture of the screen B (6). The upper screen outlet of the screen A (5) is connected to the feed port of the sand making machine. The magnetic separation device (9) and the first washing device (10) are connected to the feeding port of the sand making machine. The sand equipment (10) is arranged downstream of the wet screening equipment (4); the feed inlet of the first sand washing equipment (10) is connected to the upper screen outlet of the screen B (6); the feed inlet of the magnetic separation equipment (9) is connected to the lower screen outlet of the screen B (6); the second sand washing equipment (11) and the post-processing subsystem are arranged downstream of the magnetic separation equipment (9); the feed inlet of the second sand washing equipment (11) is connected to the concentrate outlet of the magnetic separation equipment (9); and the feed inlet of the post-processing subsystem is connected to the tailings outlet of the magnetic separation equipment (9).

2. The graded magnetic separation and water washing engineering sand making system according to claim 1, characterized in that: The pore size of the sieve A (5) is 5 mm, and the pore size of the sieve B (6) is 3 mm.

3. The graded magnetic separation and water washing engineering sand making system according to claim 1 is characterized in that: The sand making equipment (2) is a vertical shaft sand making machine.

4. The graded magnetic separation and water washing engineering sand making system according to claim 1, characterized in that: The wet screening equipment (4) is a linear vibrating screen.

5. The graded magnetic separation and water washing engineering sand making system according to claim 1, characterized in that: The magnetic separation equipment (9) is provided with a plurality of magnetic separators, and the plurality of magnetic separators are arranged in series and / or in parallel.

6. The graded magnetic separation and water washing engineering sand making system according to claim 5, characterized in that: The magnetic separator is a rotary high gradient magnetic separator.

7. The graded magnetic separation and water washing engineering sand making system according to any one of claims 1 to 6, characterized in that: The first sand washing equipment (10) comprises a first sand washing machine, wherein an inlet of the first sand washing machine is connected to an outlet above the screen of the screen B (6), and an outlet of the first sand washing machine is connected to a coarse sand bin (13); The second sand washing equipment (11) comprises a second sand washer, the inlet of the second sand washer is connected to the concentrate outlet of the magnetic separator or the second outlet (21) of the collecting hopper (7), and the outlet of the second sand washer is connected to the fine sand bin (12).

8. The graded magnetic separation and water washing engineering sand making system according to claim 7, characterized in that: The first sand washing machine and / or the second sand washing machine is a bucket wheel sand washing machine.

9. The graded magnetic separation and water washing engineering sand making system according to claim 1, characterized in that: The post-processing subsystem comprises a magnetic sand sedimentation and separation tank (15) and a sewage treatment device (17). The feed inlet of the magnetic sand sedimentation and separation tank (15) is connected to the tailings outlet of the magnetic separation device (9). The sewage outlet of the magnetic sand is connected to the sewage inlet of the sewage treatment device (17) via a sewage conveying pipeline. A sewage pump (16) is provided on the sewage conveying pipeline.

10. A graded magnetic separation and water washing engineering sand making process, characterized in that: The use of the graded magnetic separation and water washing engineering sand making system as described in any one of claims 1 to 9 comprises the following steps: S1, the sand making equipment (2) is in operation to produce artificial sand, and the artificial sand is sent to the wet screening equipment (4); S2, the wet screening device (4) operates to classify the artificial sand according to the preset particle size requirements, returns the ore with a particle size greater than 5 mm to the feeding device (1), sends the artificial sand with a particle size of 5 mm to 3 mm to the first sand washing device (10), and sends the artificial sand with a particle size less than 3 mm to the magnetic separation device (9); S3. For the two coarse and fine levels of artificial sand, the artificial sand of 5 mm to 3 mm is washed by the first sand washing device (10) to obtain coarse sand, and the artificial sand of 3 mm is magnetically separated by a magnetic separator to obtain fine concentrate, and the fine concentrate is sent to the second sand washing device (11) for washing to obtain fine sand, and the magnetic separation tailings are sent to the post-processing subsystem for separation and treatment to obtain mica as a by-product. S4. The dehydrated coarse sand is mixed back into the fine sand according to a preset gradation ratio to obtain finished sand.

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