Efficient and environment-friendly machine-made refined sand production method and application thereof

Abstract

The invention relates to an efficient and environment-friendly machine-made refined sand production method and application thereof. The method comprises the following steps: (1) feeding and screening; (2) first-stage screening and washing; (3) coarse crushing, intermediate crushing and screening; (4) second-stage sand washing; (5) fine crushing and closed-loop screening; (6) sand milling and dehydration by a wet rod mill; (7) crushing, shaping and grading; and (8) dehydrating the slurry. The dry-wet combined sand making technology is adopted, the sand forming rate is high, the quality indexes such as the mud content, the water content, grading and the stone powder content of finished sand can be well controlled in the sand making process, the finished machine-made fine sand quality is guaranteed, and the dry-wet combined sand making technology has the advantages of being small in one-time investment, low in operation management cost, clean in coarse aggregate surface, small in fine aggregate stone powder loss and the like; meanwhile, dust pollution caused by dry-method sand making can be effectively relieved, stone powder and waste water are recycled, production of the whole machine-made fine sand is efficient and clean, and high application and popularization value is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of solid waste resources, and specifically relates to a highly efficient and environmentally friendly machine-made concentrated sand production method and application thereof. Background Art

[0002] Sand and gravel aggregates are the main components of building materials such as concrete and masonry stones, accounting for 60% to 75% of their volume. They are the largest and indispensable raw materials used in infrastructure construction. They can be widely used as metallurgy, underground mining filling materials, highway asphalt, cement, hydropower concrete and general construction concrete aggregate building materials.

[0003] Sand and gravel aggregates are mainly divided into two categories according to their sources: natural sand and artificial sand. However, with the continuous exploitation and utilization of natural sand, natural sand resources are rapidly decreasing, and some areas are almost exhausted. Over-exploitation has reduced the amount of sand in rivers, causing irreparable damage to river ecology, flood control, and waterway safety. Artificial sand is a rock particle made from inert stones such as rocks, pebbles, and waste rocks from mines through mechanical crushing and screening. It is an effective substitute for natural sand. The development of artificial sand can solve the ecological balance problem of river embankments and dams caused by excessive development of natural sand, and realize the comprehensive utilization of huge mine waste rock resources. Therefore, the study of large-scale artificial sand production technology is of great significance to the harmonious and sustainable development of man and the natural environment.

[0004] At present, the commonly used artificial sand production processes are mainly dry method and wet method. The characteristics and shortcomings of these two processes are as follows: Dry sand making technology means that except for the water used for spray dust reduction in some dust removal process links, the entire sand making production line basically does not use water. It is suitable for use with the floor-standing dry aggregate shaping sand making system after medium and fine crushing. This process has high requirements on the content of impurities such as soil and organic matter in the raw materials. The content of impurities such as soil in the parent rock must be strictly controlled. Otherwise, it is very easy to cause the production system to be blocked and the dust collection system to be overloaded, the finished aggregate stone powder content exceeds the standard, the fineness modulus of the fine aggregate is high, and the dust pollution is serious.

[0005] In the wet sand making process, water will be used as a working medium and dust suppression medium in the production of sand and gravel aggregates. It can remove organic matter and other soluble impurities on the surface of sand and gravel. The finished product has a good appearance and high cleanliness. Less dust is generated during the production process. The investment in dust collection facilities is lower than that of the dry process, which is more friendly to the ecological environment. However, the wet process will cause stone powder particles to be lost in the washed mud. The finished sand contains almost no stone powder. The fine aggregate does not meet the requirements of the artificial sand fineness modulus of 2.4~2.8 in the "Specifications for Hydraulic Concrete Construction". Direct use will increase the cement content of concrete, and the mud carrying a large amount of stone powder must be treated before it can be discharged, which will inevitably increase the investment in sewage treatment. In addition, the finished sand has a high moisture content, which does not meet the requirement of the "Specifications for Hydraulic Concrete Construction" that the moisture content is less than 6%. Summary of the invention

[0006] In view of the above problems, the present invention provides a high-efficiency and environmentally friendly machine-made refined sand production method, production system and application, aiming to overcome the many problems of the existing sand making production process, such as unreasonable grading of finished sand, low sand formation rate, dust pollution or drainage pollution during production, etc., by adopting a dry-wet combined sand making process, optimize the quality of finished products, improve production efficiency and avoid secondary pollution.

[0007] The specific technical solution is: The present invention provides a highly efficient and environmentally friendly method for producing machine-made fine sand, comprising the following steps: (1) Feed screening: Use high-pressure flushing water to wet the ore and disperse the ore mud, and then use a grizzly feeder to screen the material to obtain +60mm oversize material and -60mm undersize material; (2) One-stage screening and washing: Use high-pressure washing water to screen and wash the material under the -60 mm sieve to further disperse the ore mud and separate the ore mud and lumps of stone to obtain +20 mm sieve material I and -20 mm sieve material I; (3) Coarse crushing, medium crushing and screening: The +60 mm screen-surface material is subjected to open-circuit coarse crushing, and the coarse crushed product is combined with the first-stage screen-washed +20 mm screen-surface material Ⅰ for medium crushing; after medium crushing, the medium crushed product is screened and washed with high-pressure washing water to obtain +20 mm screen-surface material Ⅱ and -20 mm screen-surface material Ⅱ; (4) Second-stage sand washing: The first-stage screening and washing - 20 mm undersize material I and the medium crushing - 20 mm undersize material II are combined for second-stage sand washing to separate the mud and clean sand; (5) Closed-circuit fine crushing and screening: Fine crushing of the medium crushing +20 mm screen material II, and further screening of the fine crushed product to obtain +15 mm screen material and -15 mm screen material; the +15 mm screen material is returned to the fine crushing equipment for cyclic fine crushing and screening until all materials are finely crushed into -15 mm qualified products; (6) Wet rod mill sand making and dehydration: The clean sand obtained from the second stage of sand washing and the part of the -15mm screen material obtained from fine crushing are combined for wet rod mill sand making. After dehydration, the rod mill product is 0.2~2.5mm finished washed sand; (7) Crushing, shaping and grading: The finely crushed part of the material under the 15mm sieve is crushed, shaped and then sieved through a double-layer sieve to obtain the finished coarse aggregate with 10-15mm on the upper sieve, the finished medium-coarse aggregate with 4.75-10mm on the lower sieve, and the finished fine sand with 0-4.75mm on the lower sieve. (8) Mud dehydration: The mud obtained from the second-stage sand washing and the dehydrated slurry from the rod mill product are concentrated and filtered to obtain fine mud and overflow water. The overflow water can be recycled after sedimentation and clarification.

[0008] Furthermore, the high-pressure flushing water in steps (1) to (3) all uses a water pressure of 0.3 to 0.5 MPa.

[0009] The present invention also provides an equipment system for the above-mentioned efficient and environmentally friendly machine-made fine sand production method, comprising a grizzly feeder, wherein the grizzly feeder screen lower material port is connected to a linear vibrating screen I, and the grizzly feeder screen upper material port is connected to a jaw crusher; the jaw crusher lower material port and the linear vibrating screen I screen upper material port are connected to a medium crushing cone crusher, and the medium crushing cone crusher lower material port is connected to a linear vibrating screen II; The screen outlets of the linear vibrating screen I and the linear vibrating screen II are both connected to a trough sand washer, the clean sand outlet of the trough sand washer is connected to a rod mill, and the discharge port of the rod mill is connected to a high-frequency dewatering screen; the slurry outlet of the trough sand washer and the slurry outlet of the high-frequency dewatering screen are both connected to a high-efficiency thickener and a plate-and-frame filter press in sequence; The feed port of the linear vibrating screen II is connected to the fine crushing cone crusher, the discharge port of the fine crushing cone crusher is connected to the heavy-duty circular vibrating screen, the feed port of the heavy-duty circular vibrating screen is connected to the feed port of the fine crushing cone crusher, the lower port of the heavy-duty circular vibrating screen is connected to the rod mill and the vertical shaft impact crusher, and the discharge port of the vertical shaft impact crusher is connected to the double-layer linear screen.

[0010] Furthermore, the jaw crusher discharge port and the medium crushing cone crusher feed port, the linear vibrating screen feed port and the medium crushing cone crusher feed port, and the heavy circular vibrating screen feed port and the fine crushing cone crusher feed port are all connected through belt conveyors and buffer ore bins.

[0011] Furthermore, the feed port of the linear vibrating screen II and the feed port of the trough sand washing machine, and the discharge port of the rod mill and the feed port of the high-frequency dewatering screen are connected through a slurry pool and a slurry pump.

[0012] Furthermore, a distribution bin is provided between the lower feed port of the heavy circular vibrating screen and the rod mill, the lower feed port of the heavy circular vibrating screen and the feed port of the distribution bin, and the discharge port of the distribution bin and the feed port of the rod mill are all connected by a belt conveyor, and a buffer ore bin is provided between the discharge port of the distribution bin and the feed port of the vertical shaft impact crusher.

[0013] Furthermore, the discharge port of the fine-crushing cone crusher and the feed port of the heavy-duty circular vibrating screen, and the discharge port of the vertical shaft impact crusher and the feed port of the double-layer linear screen are all connected through a belt conveyor.

[0014] The present invention also provides the application of the above-mentioned efficient and environmentally friendly machine-made fine sand production method and production system, wherein the method and system are applied to the production of mud-containing parent rock, stone or waste rock with a mud content of 6% < 16% or a clay plasticity index of 1 to 10.

[0015] The beneficial effects of the present invention are as follows: the present invention adopts a dry-wet combined sand making process with a high sand forming rate, controls the mud content through the "wet screening + two-stage sand washing" desludging process, controls the moisture content by combining mechanical dehydration with gravity dehydration, and combines three-stage crushing with the "wet rod mill + dry crushing and shaping" sand making process to adjust the mechanism fine sand grading and stone powder content, so that the mud content, moisture content, grading, stone powder content and other finished product quality indicators of the finished sand can be better controlled to ensure the quality of the finished mechanism fine sand, has the advantages of small one-time investment, low operation and management cost, clean coarse aggregate surface, less loss of fine aggregate stone powder, etc., and can effectively reduce the dust pollution caused by dry sand making, realize the recycling of stone powder and wastewater, and the production of the entire mechanism fine sand is efficient and clean, and has a strong value for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of a highly efficient and environmentally friendly method for producing machine-made concentrated sand in Example 1; Figure 2 This is an equipment association diagram of an efficient and environmentally friendly machine-made fine sand production system in Example 2; In the figure: 1- grizzly feeder; 2- linear vibrating screen I; 3- trough sand washer; 4- high-efficiency thickener; 5- plate and frame filter press; 6- rod mill; 8- high-frequency dewatering screen; 9- jaw crusher; 10- medium crushing cone crusher; 11- linear vibrating screen II; 13- fine crushing cone crusher; 14- heavy-duty circular vibrating screen; 15- vertical shaft impact crusher; 16- double-layer linear screen; 17- material distribution bin. DETAILED DESCRIPTION

[0017] In order to make the technical problems and technical solutions solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example 1

[0018] This embodiment provides an efficient and environmentally friendly method for producing machine-made fine sand, comprising the following steps: (1) Feed screening: Use 0.3~0.5MPa high-pressure flushing water to wet the ore and disperse the ore mud, and screen the material through a grizzly feeder to obtain +60mm oversize material and -60mm undersize material; (2) One-stage screening and washing: Use 0.3~0.5MPa high-pressure washing water to screen and wash the -60mm undersize material to further disperse the ore mud and separate the ore mud and lumps to obtain +20mm oversize material I and -20mm undersize material I; (3) Coarse crushing, medium crushing and screening: The +60 mm screen-surface material is subjected to open-circuit coarse crushing, and the coarse crushed product is combined with the first-stage screen-washed +20 mm screen-surface material Ⅰ for medium crushing; after medium crushing, the medium crushed product is screened and washed with 0.3-0.5 MPa high-pressure washing water to obtain +20 mm screen-surface material Ⅱ and -20 mm screen-surface material Ⅱ; (4) Second-stage sand washing: The first-stage screening and washing - 20 mm undersize material I and the medium crushing - 20 mm undersize material II are combined for second-stage sand washing to separate the mud and clean sand; (5) Closed-circuit fine crushing and screening: Fine crushing of the medium crushing +20 mm screen material II, and further screening of the fine crushed product to obtain +15 mm screen material and -15 mm screen material; the +15 mm screen material is returned to the fine crushing equipment for cyclic fine crushing and screening until all materials are finely crushed into -15 mm qualified products; (6) Wet rod mill sand making and dehydration: The clean sand obtained from the second stage of sand washing and the part of the -15mm screen material obtained from fine crushing are combined for wet rod mill sand making. After dehydration, the rod mill product is 0.2~2.5mm finished washed sand; (7) Crushing, shaping and grading: The finely crushed part of the material under the 15mm sieve is crushed, shaped and then sieved through a double-layer sieve to obtain the finished coarse aggregate with 10-15mm on the upper sieve, the finished medium-coarse aggregate with 4.75-10mm on the lower sieve, and the finished fine sand with 0-4.75mm on the lower sieve. (8) Mud dehydration: The mud obtained from the second-stage sand washing and the dehydrated slurry from the rod mill product are concentrated and filtered to obtain fine mud and overflow water. The overflow water can be recycled after sedimentation and clarification.

[0019] The present invention adopts a dry-wet combined sand making process, wherein the sand washing and mud removal adopts the "wet screening + two-stage sand washing" process, the stone crushing adopts the "coarse crushing-medium crushing-fine crushing" three-stage crushing process, and the sand making adopts the "wet rod mill + dry crushing and shaping" process. It can be applied to the production of mud-free parent rock, stone or waste rock with a clay plasticity index of 1 to 10 or a clay content of 6% < mud content < 16%.

[0020] The control of the key technical indicators of the machine-made fine sand production process by the present invention is as follows: (1) Control of mud content in finished sand and gravel and coarse aggregate Since the MB value of machine-made sand is proportional to the clay content, when the MB value exceeds the critical value of 1.4, the workability of fresh concrete is significantly reduced, the degree of early plastic cracking increases, and the flexural strength and 7d compressive strength of hardened concrete are significantly reduced. Therefore, it is necessary to remove the clay or fine mud in the sand and stone materials.

[0021] To this end, the present invention organically combines the "wet screening + two-stage sand washing" desludging process with the crushing process. The raw stone, coarse crushing, and medium crushed stone are screened with high-pressure water by a staged separator to separate the ore mud from the block stone, thereby effectively removing the clay or fine mud adhering to the surface of the product, so that the mud content of each particle size product is less than 1%, creating favorable conditions for the subsequent production of sand and gravel aggregates.

[0022] (2) Control of moisture content of finished sand and gravel and coarse aggregate The sand making of the present invention adopts the "wet rod mill + dry crushing and shaping" process, wherein fine crushing and crushing and shaping adopt dry crushing. Although the rod mill adopts wet grinding, the rod mill product is dehydrated by a high-frequency dehydration screen. Therefore, the coarse aggregate, machine-made fine sand, and washed sand obtained by the sand making process have low moisture content, which can be controlled within 10%. Moreover, when stacked in the finished sand bin, the moisture content can be reduced to the relevant technical requirements after gravity dehydration and natural ventilation.

[0023] (3) Optimization and control of particle size distribution Particle grading refers to the proportion of particles of various particle sizes in the aggregate. The grading composed of uninterrupted levels of particle sizes is called continuous grading, while the grading composed of only a few particle sizes is called discontinuous grading. Reasonable particle grading is an important way to obtain low porosity or low porosity in the ingredients. In order to solve the problem that the grading of dry sand making is too coarse, and the grading of wet sand making-0.16mm stone powder content is unreasonable, the present invention solves the problem by setting a "wet rod mill + dry crushing and shaping" sand making process to produce machine-made fine sand with different gradings and outputs, and then mixing. Of course, the grading of the finished aggregate can be achieved according to the specific requirements of the downstream user by adjusting the medium crushing discharge port, the fine crushing discharge port, the size of the linear screen, adjusting and distributing the feed amount of the rod mill sand making and the crushing and shaping sand making, etc. to achieve the production of aggregates of different particle sizes.

[0024] (4) Control of stone powder content Stone powder is a fine-grained powder of -0.16mm (specific surface area 325m² / kg) produced during the crushing process of the parent rock. Stone powder can replace fly ash as an admixture to prepare concrete. Different from fine mud, the MB value of methylene blue is less than 1.4, which is defined as stone powder. In the present invention, coarse crushing and medium crushing adopt wet process, and the small amount of stone powder produced enters the mud together with the fine mud during the sand washing process; fine crushing and crushing and shaping adopt dry process, and the stone powder produced in this process can directly enter the finished sand and gravel. The right amount of stone powder can effectively improve the impermeability, frost resistance and durability of concrete, and improve the workability of concrete. Similarly, the present invention can control the stone powder content in the finished sand by reasonably adjusting and distributing the feed amount of rod mill sand making and crushing and shaping sand making.

[0025] (5) Control of the particle shape of finished sand and gravel aggregate The particle shape of finished sand and gravel aggregates, especially coarse aggregates, is related to factors such as the structure of the parent rock, the crushing process and the performance of the equipment. It is difficult to avoid the production of a certain amount of needle-shaped and flake-shaped aggregates. The coarse crushing of the present invention adopts a jaw crusher for open-circuit crushing to -180mm, and the medium and fine crushing adopt a cone crusher for full feeding and laminated closed-circuit crushing. The cone crusher has good stability, uniform particle shape of the crushed products, a wide range of discharging adjustment, and greater flexibility in adjusting the product grading. Wet screening is set after medium crushing, and dry closed-circuit screening is set after fine crushing, combining dry and wet. A part of the fine crushed -15mm particle size enters the vertical shaft impact crusher for crushing and shaping (four-stage crushing). The feeding gradation is continuous. During the entire crushing and shaping process, the materials collide and shape each other. The product particle shape is cubic, with few flake and needle-shaped particles (content < about 5%). The crushed products are continuously graded and screened by double-layer linear screen dry type to produce three kinds of finished products: 0~4.75mm fine sand, 4.75~10mm medium coarse aggregate and 10~15mm coarse aggregate.

[0026] (6) Disposal of sand washing slurry The present invention adopts a dry-wet combined process, which can overcome the dust pollution problem of dry sand making and reduce the water consumption of wet sand making, and is a green and environmentally friendly sand making process. After the sand washing slurry is concentrated and filtered, drainage treatment is achieved, and the overflow water can be returned to the sand washing water point for recycling after sedimentation and clarification, which can further reduce the consumption of new water and comply with relevant national policies such as energy conservation and emission reduction.

[0027] To sum up, the present invention adopts the dry-wet combined sand making process with a high sand formation rate, controls the mud content by washing and demuding, controls the moisture content by combining mechanical dehydration with gravity dehydration, and adjusts the fineness modulus and stone powder content of the finished sand by combining dry-wet sand making, so that the mud content, moisture content, grading, stone powder content and other finished product quality indicators of the finished sand can be better controlled to ensure the quality of the finished machine-made fine sand, has the advantages of small one-time investment, low operation and management cost, clean coarse aggregate surface, less loss of fine aggregate stone powder, etc., and can effectively reduce the dust pollution caused by dry sand making, realize the recycling of stone powder and wastewater, and the production of the entire machine-made fine sand is efficient and clean, and has a strong value for promotion and application. Application Example 1

[0028] A sand and gravel aggregate plant has a processing capacity of 3000t / d. The stone materials are waste rocks stripped from open-pit mining, mainly limestone. The crushing work index is about 14.70kW·h / t, and the raw material sludge content is about 8%.

[0029] The method described in Example 1 is used to make sand from the above-mentioned stone, using "wet screening + two-stage sand washing" for desludging, "coarse crushing-medium crushing-fine crushing" three-stage crushing, and "wet rod mill + dry crushing and shaping" for sand making. The main equipment selection in the production process is: coarse crushing uses a C100 jaw crusher produced by Metso Outotec, which is used to process mine waste stones with a particle size of +60mm~+650mm mined from quarries; medium crushing uses a Metso Outotec HP300 hydraulic cone crusher, which is used to process -180mm coarse crushed products and one-stage screening and washing screen materials; fine crushing uses Metso Outotec HP300 fine crushing hydraulic cone crusher, crushing and shaping uses Metso B6150SE vertical shaft impact crusher, and wet sand making equipment uses BM2740 wet rod mill. The main technical indicators of the finished product are shown in Table 1: Table 1: Main technical indicators of sand making products

[0030] Among them, 0~0.2mm stone powder was washed out, fine mud accounted for about 16%, and the output was about 480t / d.

[0031] The fineness modulus of the finished fine aggregate is between 2.3 and 3.0, the gradation is continuous, the stone powder content is between 10% and 18%, and the moisture content is controlled at about 10% before entering the warehouse. After gravity dehydration and natural ventilation, the moisture content can be reduced to less than 6%. The production return water rate is ≥80%, and the power consumption is about 3.5 degrees / t. The finished sand meets the requirements of sand and gravel aggregate for underground filling in mines. Application Example 2

[0032] A hydropower sand and gravel plant is located near the dam site of a hydropower station with abundant water resources. The processed stones are mainly granite and limestone. The rock hardness is medium and the parent rock is medium abrasive. The designed processing capacity is 550t / h.

[0033] The original production process adopted dry sand making, through the process of "pre-screening-coarse crushing-medium crushing-fine crushing", pre-screening and screening out -150mm raw ore before coarse crushing, coarse crushing uses a Sandvik CJ612 jaw crusher, and the discharge port CSS=150mm; medium crushing uses a Sandvik CS440C cone crusher, with an eccentricity of 36mm and a tight side discharge port CSS=44mm; before fine crushing, pre-screening is set to output -5mm fine aggregate, and fine crushing uses two CH440MF fine crushing cone crushers, with an eccentricity of 44mm and a tight side discharge port CSS=22mm. Two double-layer linear vibrating screens are selected to form a closed-circuit screening with fine crushing. The +31.5mm on the upper screen is returned for fine crushing, the 20~30mm on the lower screen is transferred to the finished material yard to produce 20~30mm coarse aggregate, the -20mm under the lower screen is transferred to the double-layer linear screen for secondary screening, the 10~20mm finished aggregate on the secondary screening is produced and transferred to the material yard for storage, the -10mm material under the screen is then crushed and shaped by two Sandvik SC2462 vertical shaft impact crushers and two linear screens for closed-circuit screening, the +5mm on-screen product is returned to the vertical shaft impact crusher, the -5mm under-screen product is adjusted by two powder selectors to adjust the fine sand and stone powder content to produce -5mm finished sand.

[0034] In the actual production process, due to the high mud content in the raw materials, the use of dry sand making results in problems such as blocked processes during the rainy season, low sand formation rate of finished sand (0~5mm), unbalanced grading, and excessive mud content in the finished product.

[0035] After sand making by the method described in Example 1, the fineness modulus of the finished sand is controlled at about 2.8, and the stone powder content is controlled at 14%, which solves the problems of unsmooth flow in the rainy season, excessive mud content in the finished product, unbalanced grading, and dust production when granite and limestone are used as raw materials to produce aggregates. The comparison of the main technical indicators after the implementation of the two sand making methods is shown in Table 2: Table 2: Comparison of main technical indicators of two sand making methods

[0036] It can be seen from Table 2 above that by using the method of the present invention to make sand from parent rocks of different lithologies such as limestone, granite, and limestone, relatively ideal finished sand and gravel can be obtained. The gradation of the finished sand and gravel is continuous, and the stone powder content is relatively reasonable, which can meet the needs of concrete production. Example 2

[0037] This embodiment provides an efficient and environmentally friendly production system for machine-made fine sand used in the above-mentioned embodiment 1, including a grizzly feeder 1, the grizzly feeder 1 screen lower material port is connected to a linear vibrating screen Ⅰ2, and the grizzly feeder 1 screen upper material port is connected to a jaw crusher 9; the jaw crusher 9 lower material port and the linear vibrating screen Ⅰ2 screen upper material port are both connected to a medium crushing cone crusher 10 through a belt conveyor and a buffer ore bin, and the medium crushing cone crusher 10 lower material port is connected to a linear vibrating screen Ⅱ11; The screen underfeed ports of the linear vibrating screen Ⅰ2 and the linear vibrating screen Ⅱ11 are both connected to the trough sand washer 3, and the screen underfeed port of the linear vibrating screen Ⅱ11 is connected to the feed port of the trough sand washer 3 through a slurry pool and a slurry pump; the clean sand outlet of the trough sand washer 3 is connected to the rod mill 6, and the discharge port of the rod mill 6 is connected to the high-frequency dewatering screen 8 through a slurry pool and a slurry pump; the mud outlet of the trough sand washer 3 and the slurry port of the high-frequency dewatering screen 8 are sequentially connected to the high-efficiency thickener 4 and the plate-and-frame filter press 5; The upper feeding port of the linear vibrating screen II 11 is connected to the fine crushing cone crusher 13, the discharge port of the fine crushing cone crusher 13 is connected to the feeding port of the heavy circular vibrating screen 14 through a belt conveyor, the upper feeding port of the heavy circular vibrating screen 14 is connected to the feeding port of the fine crushing cone crusher 13 through a belt conveyor and a buffer ore bin, the lower feeding port of the heavy circular vibrating screen 14 is connected to the rod mill 6 and the vertical shaft impact crusher 15, and the discharge port of the vertical shaft impact crusher 15 is connected to the feeding port of the double-layer linear screen 16 through a belt conveyor.

[0038] Furthermore, a distribution bin 17 is provided between the lower feed port of the heavy circular vibrating screen 14 and the rod mill 6; a belt conveyor is connected between the lower feed port of the heavy circular vibrating screen 14 and the feed port of the distribution bin 17, and between the discharge port of the distribution bin 17 and the feed port of the rod mill 6; a buffer ore bin is also provided between the discharge port of the distribution bin 17 and the feed port of the vertical shaft impact crusher 15.

[0039] It should also be noted that the above equipment is all existing equipment, and the present invention does not involve the modification of the equipment, but only involves the use of the above existing equipment. Of course, the gradation of the finished aggregate can be achieved according to the specific requirements of the downstream user by adjusting the discharge port of the medium crushing cone crusher 10, the discharge port of the fine crushing cone crusher 13, the linear vibrating screen, the heavy circular vibrating screen and the double-layer linear screen screen size, adjusting and distributing the feed amount of the rod mill and the vertical shaft impact crusher, etc. to achieve the production of aggregates of different particle sizes. The control of the stone powder content in the finished sand can be achieved by reasonably adjusting and distributing the feed amount of the rod mill and the vertical shaft impact crusher.

[0040] Working principle: (1) Feeding and screening: Feed the waste rock into the rod feeder 1, use 0.3~0.5MPa high-pressure flushing water to wet the ore and disperse the ore mud to obtain +60mm oversize material and -60mm undersize material.

[0041] (2) One-stage screening and washing: The -60 mm undersize material of the grizzly feeder 1 is transferred to the linear vibrating screen Ⅰ2 for one-stage screening and washing to further disperse the ore mud and separate the ore mud and lumps of stone, thereby obtaining the +20 mm oversize material Ⅰ and the -20 mm undersize material Ⅰ.

[0042] (3) Coarse crushing, medium crushing and screening: The +60 mm above-sieve material of the grizzly feeder 1 is transferred to the jaw crusher 9 for coarse crushing. The coarse crushed product and the first-stage screened +20 mm above-sieve material Ⅰ are transferred to the medium crushing cone crusher 10 through a belt conveyor and a buffer ore bin for medium crushing. After medium crushing, the product is transferred to the linear vibrating screen Ⅱ 11, and the medium crushed product is screened and washed with 0.3~0.5 MPa high-pressure washing water to obtain +20 mm above-sieve material Ⅱ and -20 mm below-sieve material Ⅱ.

[0043] (4) Second stage sand washing: The first stage screening -20mm undersize material Ⅰ and the medium crushing screening -20mm undersize material Ⅱ are combined and transferred to the trough sand washing machine 3 for second stage sand washing operation to separate the mud and clean sand.

[0044] (5) Closed-circuit screening: The +20 mm screen-surface material II is transferred to the buffer ore bin and then to the fine-crushing cone crusher 13 for fine crushing. After fine crushing, it is transferred to the heavy-duty circular vibrating screen 14 through a belt conveyor for screening to obtain +15 mm screen-surface material and -15 mm screen-surface material; the +15 mm screen-surface material is returned to the fine-crushing cone crusher 13 through a belt conveyor for cyclic fine crushing and screening until all materials are finely crushed into -15 mm qualified products.

[0045] (6) Wet rod grinding and dehydration: The clean sand from the second-stage sand washing and the finely sieved part of the -15mm screened material (after passing through the distribution bin 17 and the belt conveyor) are transferred to the rod mill 6 for wet rod grinding and sand making. The rod mill product is transferred to the high-frequency dehydration screen 8 for dehydration through the slurry pool and slurry pump. The dehydrated product is washed sand (0.2~2.5mm).

[0046] (7) Crushing, shaping and grading: The finely crushed and screened part - the 15mm undersize material is transferred to the vertical shaft impact crusher 15 through the buffer ore bin for crushing and particle shaping, and then transferred to the double-layer linear screen 16 by the belt conveyor for double-layer screening. The product on the upper screen is 10~15mm finished coarse aggregate, the product on the lower screen is 4.75~10mm finished medium coarse aggregate, and the product under the lower screen is 0~4.75mm machine-made fine sand.

[0047] (8) Mud dehydration: The mud from the second-stage sand washing and the dehydrated slurry from the rod mill product are transferred to the high-efficiency thickener 4 for concentration. After concentration, they are filtered through the plate and frame filter press 5 to obtain fine mud and overflow water. The overflow water can be recycled and reused after sedimentation and clarification in the recovery tank.

[0048] The production system described in the present invention is designed according to the generation method described in Example 1, and has supporting equipment corresponding to the "wet screening + two-stage sand washing" demuding process, the "coarse crushing-medium crushing-fine crushing" three-stage crushing process, and the "wet rod mill + dry crushing and shaping" sand making process. It can be applied to the production of mud-free, 6% < mud content < 16% or mud-containing parent rock, stone or waste rock with a clay plasticity index of 1 to 10.

[0049] The production system controls the mud content through sand washing and demudging equipment, controls the moisture content by combining mechanical dewatering equipment with gravity dewatering, and adjusts the fineness modulus and stone powder content of the finished sand through dry-wet combined sand making equipment, so that the mud content, moisture content, grading, stone powder content and other finished product quality indicators of the finished sand can be better controlled, the sand formation rate is high, and the quality of the finished machine-made fine sand is good. It has the advantages of small one-time investment, low operation and management cost, clean coarse aggregate surface, and less loss of fine aggregate stone powder. At the same time, it can effectively reduce the dust pollution caused by dry sand making and realize the recycling of stone powder and wastewater. The production of the entire machine-made fine sand is efficient and clean, and has a strong value for promotion and application.

[0050] The present invention is described in detail above through specific and preferred embodiments, but those skilled in the art should understand that the present invention is not limited to the embodiments described above, and any modifications, equivalent substitutions, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A highly efficient and environmentally friendly method for producing machine-made fine sand, characterized in that: The steps include: (1) Feed screening: Use high-pressure flushing water to wet the ore and disperse the ore mud, and then use a grizzly feeder to screen the material to obtain +60mm oversize material and -60mm undersize material; (2) One-stage screening and washing: Use high-pressure washing water to screen and wash the material under the -60 mm sieve to further disperse the ore mud and separate the ore mud and lumps of stone to obtain +20 mm sieve material I and -20 mm sieve material I; (3) Coarse crushing, medium crushing and screening: The +60 mm screen-surface material is subjected to open-circuit coarse crushing, and the coarse crushed product is combined with the first-stage screen-washed +20 mm screen-surface material Ⅰ for medium crushing; after medium crushing, the medium crushed product is screened and washed with high-pressure washing water to obtain +20 mm screen-surface material Ⅱ and -20 mm screen-surface material Ⅱ; (4) Second-stage sand washing: The first-stage screening and washing - 20 mm undersize material I and the medium crushing - 20 mm undersize material II are combined for second-stage sand washing to separate the mud and clean sand; (5) Closed-circuit fine crushing and screening: Fine crushing of the medium crushing +20 mm screen material II, and further screening of the fine crushed product to obtain +15 mm screen material and -15 mm screen material; the +15 mm screen material is returned to the fine crushing equipment for cyclic fine crushing and screening until all materials are finely crushed into -15 mm qualified products; (6) Wet rod mill sand making and dehydration: The clean sand obtained from the second stage of sand washing and the part of the -15mm screen material obtained from fine crushing are combined for wet rod mill sand making. After dehydration, the rod mill product is 0.2~2.5mm finished washed sand; (7) Crushing, shaping and grading: The finely crushed part of the material under the 15mm sieve is crushed, shaped and then sieved through a double-layer sieve to obtain the finished coarse aggregate with 10-15mm on the upper sieve, the finished medium-coarse aggregate with 4.75-10mm on the lower sieve, and the finished fine sand with 0-4.75mm on the lower sieve. (8) Mud dehydration: The mud obtained from the second-stage sand washing and the dehydrated slurry from the rod mill product are concentrated and filtered to obtain fine mud and overflow water. The overflow water can be recycled after sedimentation and clarification.

2. The method for producing a highly efficient and environmentally friendly machine-made fine sand according to claim 1, characterized in that: The high-pressure flushing water in steps (1) to (3) all uses a water pressure of 0.3 to 0.5 MPa.

3. The application of a highly efficient and environmentally friendly machine-made fine sand production method as claimed in claim 1 or 2, characterized in that: The method is applied to the production of mud-containing parent rock, stone or waste rock with a mud content of 6% < 16% or a clay plasticity index of 1-10.

Images