A method for removing biotite during the processing of manufactured sand

Abstract

A method for removing biotite during the processing of manufactured sand relates to a method for processing manufactured sand using artificial aggregates. The method includes: 1) screening and grading the crushed semi-finished sand through a screen, with a manufactured sand collection hopper located below the bottom of the screen, into which the screened semi-finished sand enters; 2) arranging water flushing points above the manufactured sand collection hopper at the bottom of the screen, using these points to flush the semi-finished sand in the hopper; 3) arranging a spiral sand washer below the manufactured sand collection hopper, through which the semi-finished sand enters a dewatering screen for dewatering, and finally enters a finished sand conveyor belt, which transports the finished sand into a storage silo; 4) tailings treatment. This invention abandons a single dry or single wet production process in the processing of artificial aggregates, adopting a semi-dry screening method to remove biotite, thus solving the technical problem that raw rocks with excessive biotite content cannot be used for sand production.

Description

Technical fields:

[0001] A method for removing biotite during the processing of manufactured sand, relating to a method for processing manufactured sand as artificial aggregate. Background technology:

[0002] In infrastructure construction projects such as water conservancy and hydropower engineering, and non-metallic mining industries, manufactured sand and gravel (artificial aggregate) processing systems are required for material supply. This type of manufactured sand and gravel is produced by crushing the original rock and then screening it into particles of different sizes through multiple layers of screens. Because the original rock is rich in mica, a large amount of free mica is formed in the finished sand after crushing by the artificial aggregate processing system. Extensive data shows that excessive mica in manufactured sand can affect the durability of concrete. The most common methods for removing free mica from finished sand are dry production process air classification and wet production process flotation. Dry production process, simply put, involves no water being added during aggregate crushing, screening, and grading. The semi-finished sand, mixed with mica, is then air-separated to remove mica before entering the finished sand silo. However, the air-separation method in dry production has a significant impact on environmental protection and is detrimental to the occupational health of system operators. Wet production process, using flotation, involves screening the material obtained from crushing, then using a spiral chute to remove mica, followed by washing the separated material to obtain finished sand and sand-containing wastewater. Finally, the sand-containing wastewater is screened to remove mica, and the final product is recovered through a stone powder recovery device. This method is suitable for materials with a relatively low specific gravity (2.7–2.88 g / cm³). 3 The method of removing muscovite with this method has a good removal effect, but it is not suitable for biotite with a specific gravity of 3.0–3.1 g / cm³. 3 The biotite content is greater than that of water and aggregate, therefore water washing is insufficient for effective removal. Biotite is a type of mica mineral, a silicate mineral; it is mainly found in metamorphic rocks, but also in granite and other rocks; biotite ranges in color from black to brown, red, or green, has a vitreous luster, and is tabular or columnar in shape. Therefore, original rocks with excessive biotite content (approximately 11.2% biotite content in the quarry's original rock) cannot be used for sand making. Furthermore, this method requires the water washing point to be located at the top of the screen during material screening, meaning all screen layers and the artificial sand hopper must be thoroughly washed with water. Both coarse and fine aggregate grading involve water washing, and the water volume is between 95 and 100 mg / L. 3 The high water volume ( / h) results in a strong stripping effect on the mica embedded in the coarse aggregate during washing, which is detrimental to the removal of mica in later screening processes. Furthermore, this wet production process directly recovers stone powder in the tailrace pond via flotation, and the mica removal from the recovered stone powder is incomplete. This means that when the recovered stone powder is used to blend back into the finished sand, it affects the mica content of the finished sand. Summary of the Invention:

[0003] The problem this invention aims to solve is to address the above-mentioned shortcomings by providing a method for removing biotite using a semi-dry screening method in the processing of artificial aggregates, instead of a single dry or single wet production process. The technical solution is as follows:

[0004] A method for removing biotite during the processing of manufactured sand, the key technology of which includes the following steps:

[0005] 1) The crushed semi-finished sand is screened and graded through a screen. An artificial sand collection hopper is set below the bottom of the screen, and the screened semi-finished sand enters the artificial sand collection hopper.

[0006] 2) A water flushing point is arranged at the bottom of the screen above the artificial sand collection hopper. The semi-finished sand in the artificial sand collection hopper is flushed with water through the water flushing point. The water consumption of the water flushing point is 30-40 m³. 3 / h;

[0007] 3) A spiral sand washing machine is installed below the artificial sand collection hopper. The semi-finished sand in the artificial sand collection hopper enters the dewatering screen through the spiral sand washing machine for dewatering, and finally enters the finished sand conveyor belt, which sends the finished sand into the warehouse.

[0008] 4) Wastewater treatment:

[0009] ① Wastewater from the crushing workshop is directed to one of the tailings ponds, while wastewater from the screening workshop is directed to another tailings pond;

[0010] ②The stone powder in the tailwater pool is recovered by the stone powder recovery device and then mixed back into the finished sand by the finished sand conveyor belt.

[0011] Preferably, a magnetic separator is installed between the artificial sand collection hopper and the spiral sand washing machine. The semi-finished sand in the artificial sand collection hopper enters the spiral sand washing machine after passing through the magnetic separator, and then enters the dewatering screen for dewatering.

[0012] Preferably, a pre-sedimentation stone powder recovery tank is installed next to the tailwater tank. Wastewater from the crushing and screening workshops is directed to the pre-sedimentation stone powder recovery tank. After the solids settle in the pre-sedimentation stone powder recovery tank, the excess water enters the tailwater tank.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. A semi-dry screening process of "dry screening + bottom water rinsing" is adopted, that is, the water rinsing point is adjusted from the top of the screen in the original wet process to the artificial sand collection hopper, and the water volume is reduced from 95-100 mg / L in the original wet process. 3 / h adjusted to 30-40m 3 / h. The mica content of the bottom sand produced by the original wet process before passing through the spiral sand washer is 4.3-5.2%, while the mica content of the bottom sand produced by the semi-dry screening method adopted in this invention is 2.9-3.6% before passing through the magnetic separator. At this stage, the mica content of the bottom sand produced by the original wet process is 1%-2% higher than that produced by the method of this invention, and it also increases the fineness modulus of the finished sand. This proves that large-volume washing does have a strong effect on stripping the mica embedded in the coarse aggregate, which is not conducive to the removal of mica in the later stages of screening. Therefore, the specific water addition amount of this invention plays a significant role in maximizing the removal of biotite from the finished sand. As can be seen from the above, the "semi-dry screening method" of this invention refers to adjusting the water addition point to the artificial sand collection hopper, so that no water is added to each layer of the screen surface, which is a dry screening method. At the same time, only the sand and gravel in the artificial sand collection hopper are washed, hence the name "semi-dry screening method".

[0015] 2. Adding a magnetic separator between the artificial sand collection hopper and the spiral sand washing machine to remove biotite can effectively reduce the mica content in artificially produced sand. The finished sand produced by the method of this invention has a mica content of 2.8%–3.6%, with an average content of 3.2%, while the finished sand produced by the original wet process has a mica content of 3.5%–5.2%, with an average content of 4.4%. The mica content in the finished sand produced by the method of this invention is reduced by about 1.3%, and the mica content in the finished sand meets the usage requirements, solving the technical problem that the original rock with excessive biotite content cannot be used for sand making.

[0016] 3. This invention adopts a dry screening method with separate water addition to the artificial sand collection hopper, which not only solves the environmental protection problem of dry sand and gravel processing system, but also protects the occupational health of system operators.

[0017] 4. In the original wet process, the water washing point was at the top of the screen, and both coarse and fine aggregates were washed with water during grading. On the one hand, the large volume of water washing had a strong effect on stripping the mica embedded in the coarse aggregate, resulting in a high mica content in the fine aggregate. On the other hand, the large volume of water washing resulted in a high moisture content in the sand entering the magnetic separator, and a large amount of stone powder and some mud coated the mica, which was not conducive to the efficiency of the magnetic separator. In contrast, the method of this invention directly uses a dry screen, and at the same time adjusts the water washing point to the artificial sand collection hopper and reduces the water volume, so that the moisture content of the sand entering the magnetic separator is low. This significantly increases the amount of mica adsorbed on the magnetic separator, resulting in a significant magnetic separation effect, allowing the magnetic separator to fully utilize its effectiveness, and removing the biotite from the finished sand to the greatest extent.

[0018] 5. The method of the present invention utilizes the physical property of mica's high specific gravity to perform a stone powder recovery and pre-sedimentation treatment on the mica-rich effluent before treatment, which makes the removal of mica more effective.

[0019] Instruction manual illustrations:

[0020] Figure 1This is a process flow diagram of the present invention;

[0021] Figure 2 This is another process flow diagram of the present invention;

[0022] Figure 3 This is an enlarged schematic diagram of a portion of the tailwater treatment device of the present invention;

[0023] Figure 4 This is another process flow diagram of the present invention;

[0024] Figure 5 This is another process flow diagram of the present invention;

[0025] Figure 6 This is a schematic diagram illustrating the working principle of the magnetic separator of the present invention. Detailed implementation method:

[0026] Example 1:

[0027] See Figure 1 The key technology of the biotite removal method in the manufactured sand processing of this embodiment includes the following steps:

[0028] 1) The semi-finished sand 2 with a particle size <40mm after fine crushing and vertical shaft crushing in the crushing workshop is mixed and then screened and graded by a multi-layer screen of screening equipment 1 in the screening workshop. Artificial sand collection hopper 3 is set below the bottom of the screen. The multi-layer screen is arranged in N layers from top to bottom, including the top screen 1.1 and the bottom screen 1.2. The top screen 1.1 has 2 or 3 layers. The aperture of each top screen is 10mm to 40mm. The bottom screen 1.2 has square or round holes with a diameter of 3mm to 5mm. The optimal aperture is 3mm or 5mm. The coarse aggregate after grading on the screen surface is directly discharged to the coarse aggregate bin. The semi-finished sand with a particle size less than or equal to 3mm or 5mm enters the artificial sand collection hopper 3.

[0029] 2) A water flushing point 3.1 is arranged at the bottom of the screen above the artificial sand collection hopper 3. The semi-finished sand in the artificial sand collection hopper 3 is flushed with water through the water flushing point 3.1 (no water is passed through any layer of the screen surface). The water consumption of the water flushing point 3.1 is 30-40 ml. 3 / h;

[0030] 3) The semi-finished products in the artificial sand collection hopper 3 enter the spiral sand washing machine 5. After being washed by the spiral sand washing machine 5, the sand enters the dewatering screen 6 for dewatering. Finally, it enters the finished sand conveyor belt, which sends the finished sand 2.1 into the warehouse.

[0031] The above steps for water supply (B) are as follows: water source → artificial sand collection hopper 3 → spiral sand washing machine 5 → dewatering screen 6.

[0032] The spiral sand washer 5 and the dewatering screen 6 are existing technologies, and will not be described in detail here.

[0033] 4) Wastewater treatment:

[0034] The tailwater treatment device includes a tailwater pool 7, which is connected to a stone powder recovery device 9 via a pipeline. Two such tailwater treatment devices are arranged: wastewater from the crushing workshop is led to one tailwater pool 7 through a drainage ditch, and wastewater from the spiral sand washing machine and dewatering screen in the screening workshop is led to the other tailwater pool 7 through another drainage ditch. The material in the tailwater pool 7 is recovered by the stone powder recovery device 9, and the screened stone powder is returned to the finished sand conveyor belt and then mixed back into the finished sand.

[0035] The diagram shows the flow direction of the semi-finished sand, indicated by arrow A.

[0036] Example 2:

[0037] like Figure 2 , Figure 3 As shown, this embodiment describes a method for removing biotite during the processing of manufactured sand. The other devices and steps are the same as in Embodiment 1, except that a pre-sedimentation stone powder recovery tank 8 is installed next to the tailwater tank 7. An overflow port 8.1 is provided between the pre-sedimentation stone powder recovery tank 8 and the tailwater tank 7. A filter screen is installed on the overflow port 8.1 to ensure that the water entering the tailwater tank 7 does not contain materials with non-compliant particle sizes. The tailwater tank 7 is connected to a stone powder recovery device 9 via a pipeline. The tailwater treatment includes the following steps:

[0038] ① Wastewater from the crushing workshop is led to one of the pre-sedimentation stone powder recovery tanks 8 through a drainage ditch. Wastewater from the spiral sand washing machine and dewatering screen in the screening workshop is led to another pre-sedimentation stone powder recovery tank 8 through another drainage ditch. Solids are settled in the pre-sedimentation stone powder recovery tank 8. All the recovered materials after settling are transported to the waste bin for disposal as waste.

[0039] ② Excess water from the pre-sedimentation stone powder recovery tank 8 enters the tailwater tank 7 from the overflow outlet 8.1;

[0040] ③ The material in the tailwater tank 7 is recycled to the finished sand conveyor belt by the stone powder recovery device 9, and then mixed back into the finished sand to ensure that the fineness modulus of the finished sand meets the specifications.

[0041] Example 3:

[0042] See Figure 4 , Figure 6In this embodiment, the method for removing biotite during the processing of manufactured sand is the same as in Embodiment 1. The key technology is that a magnetic separator 4 is arranged between the artificial sand collection hopper 3 and the spiral sand washing machine 5. The semi-finished sand in the artificial sand collection hopper 3 enters the spiral sand washing machine 5 after passing through the magnetic separator 4. After being washed by the spiral sand washing machine 5, it enters the dewatering screen 6 for dewatering and finally enters the finished sand conveyor belt, which sends the finished sand 2.1 into the warehouse.

[0043] like Figure 6 As shown, the magnetic separator 4 mentioned above uses a mature wet permanent magnet high gradient plate magnetic separator. Its working principle is as follows: semi-finished sand enters the feed box 4.4 of the magnetic separator from the bottom of the screen. It is evenly fed onto the separating belt 4.3 through the feed box 4.4. The magnetic field strength of the magnetic separator is between 13000 and 20000 GS, with a processing capacity of 30 t / h. Therefore, all magnetic materials are adsorbed onto the separating belt 4.3 and carried to the top of the magnetic separator by the movement of the separating belt 4.3. Non-magnetic materials mixed in with the magnetic materials are flushed out through the material-iron separation flushing pipe. These non-magnetic materials are washed down with water and directly enter the discharge port 4.2. The sand and gravel at the discharge port 4.2 enter the spiral sand washer 5. Magnetic materials are carried to the non-magnetic area at the rear by the scraper on the belt. The magnetic materials are flushed down through the iron discharge flushing pipe 4.5 and enter the iron outlet 4.6, completing the material separation. Figure 4.1 shows the frame of the magnetic separator.

[0044] The above steps for water supply (B) are as follows: water source → artificial sand collection hopper 3 → magnetic separator 4 → spiral sand washer 5 → dewatering screen 6.

[0045] The wastewater treatment steps are the same as in Example 1.

[0046] Example 4:

[0047] like Figure 5 , Figure 6 , Figure 3 As shown, a method for removing biotite during the processing of manufactured sand, the key technology of which includes the following steps:

[0048] 1) The semi-finished sand 2 with a particle size <40mm after fine crushing and vertical shaft crushing in the crushing workshop is mixed and then screened and graded by a multi-layer screen of screening equipment 1 in the screening workshop. Artificial sand collection hopper 3 is set below the bottom of the screen. The multi-layer screen is arranged in N layers from top to bottom, including the top screen 1.1 and the bottom screen 1.2. The top screen 1.1 has 2 or 3 layers. The aperture of each top screen is 10mm to 40mm. The bottom screen 1.2 has square or round holes with a diameter of 3mm to 5mm. The optimal aperture is 3mm or 5mm. The coarse aggregate after grading on the screen surface is directly discharged to the coarse aggregate bin. The semi-finished sand with a particle size less than or equal to 3mm or 5mm enters the artificial sand collection hopper 3.

[0049] 2) A water flushing point 3.1 is arranged at the bottom of the screen above the artificial sand collection hopper 3. The semi-finished sand in the artificial sand collection hopper 3 is flushed with water through the water flushing point 3.1 (no water is passed through any layer of the screen surface). The water consumption of the water flushing point 3.1 is 30-40 ml. 3 / h;

[0050] 3) A magnetic separator 4 is arranged below the artificial sand collection hopper 3. The semi-finished sand in the artificial sand collection hopper 3 enters the spiral sand washing machine 5 after passing through the magnetic separator 4. After being washed by the spiral sand washing machine 5, it enters the dewatering screen 6 for dewatering and finally enters the finished sand conveyor belt, which sends the finished sand 2.1 into the warehouse.

[0051] The working principle, water supply process, device and sand washing principle of the magnetic separator 4, the spiral sand washer 5 and the dewatering screen 6, and the dewatering principle are all the same as those in Example 3.

[0052] 4) Wastewater treatment:

[0053] ①For example Figure 5 , Figure 3 As shown, the wastewater treatment device includes a pre-sedimentation stone powder recovery tank 8 and a wastewater tank 7 connected thereto. An overflow outlet 8.1 is provided between the pre-sedimentation stone powder recovery tank 8 and the wastewater tank 7. The wastewater tank 7 is connected to the stone powder recovery device 9 through a pipeline. Two such wastewater treatment devices are arranged: wastewater from the crushing workshop is led to one of the pre-sedimentation stone powder recovery tanks 8 through a drainage ditch, and wastewater from the spiral sand washing machine and dewatering screen in the screening workshop is led to another pre-sedimentation stone powder recovery tank 8 through another drainage ditch. Solids are settled in the pre-sedimentation stone powder recovery tank 8, and all the recovered materials after sedimentation are transported to the waste bin for disposal as waste.

[0054] ② Excess water from the pre-sedimentation stone powder recovery tank 8 enters the tailwater tank 7 through the overflow port 8.1. A filter screen is installed on the overflow port 8.1 to ensure that the water entering the tailwater tank 7 does not contain materials with non-compliant particle sizes.

[0055] ③ The material in the tailwater tank 7 is recycled to the finished sand conveyor belt by the stone powder recovery device 9, and then mixed back into the finished sand to ensure that the fineness modulus of the finished sand meets the specifications.

[0056] The diagram shows the flow direction of the semi-finished sand, indicated by arrow A.

[0057] Comparison of mica content detection results in finished sand from existing wet production processes and the method of this invention:

[0058]

[0059] Comparative analysis of the data in the table above shows that the mica content in the finished sand is reduced by about 1.3% compared with the existing wet process: "water addition to screen bottom hopper + magnetic separation" and "existing wet process". This indicates that the method of the present invention can more effectively reduce the mica content in the finished sand.

Claims

1. A method for removing biotite during the processing of manufactured sand, characterized in that... Includes the following steps: 1) The crushed semi-finished sand (2) is screened and graded through a screen. A sand collection hopper (3) is set below the bottom of the screen. The screened semi-finished sand enters the sand collection hopper (3). 2) A water flushing point (3.1) is arranged at the bottom of the screen above the artificial sand collection hopper (3). The semi-finished sand in the artificial sand collection hopper (3) is flushed with water through the water flushing point (3.1). The water consumption of the water flushing point (3.1) is 30-40 m³. 3 / h; 3) A spiral sand washing machine (5) is arranged below the artificial sand collection hopper (3). The semi-finished sand in the artificial sand collection hopper (3) enters the dewatering screen (6) through the spiral sand washing machine (5) for dewatering, and finally enters the finished sand conveyor belt, which sends the finished sand (2.1) into the warehouse. 4) Wastewater treatment: ① Wastewater from the crushing workshop is directed to one of the tailings ponds (7), and wastewater from the screening workshop is directed to another tailings pond (7); ②The material in the tailwater pool (7) is recycled to the finished sand by the stone powder recovery device (9), and the screened stone powder is returned to the finished sand by the finished sand conveyor belt.

2. The method for removing biotite during the processing of manufactured sand according to claim 1, characterized in that... A magnetic separator (4) is installed between the artificial sand collection hopper (3) and the spiral sand washing machine (5). The semi-finished sand in the artificial sand collection hopper (3) enters the spiral sand washing machine (5) after passing through the magnetic separator (4), and then enters the dewatering screen (6) for dewatering by the spiral sand washing machine (5).

3. The method for removing biotite during the processing of manufactured sand according to claim 1 is characterized in that a pre-precipitated stone powder recovery tank (8) is installed next to the tailwater tank (7), and the wastewater produced by the crushing workshop and the screening workshop is led to the pre-precipitated stone powder recovery tank (8). After the solids are settled in the pre-precipitated stone powder recovery tank (8), the excess water enters the tailwater tank (7).

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