Process method for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings

Abstract

The invention relates to a process method for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings, which comprises the following steps: S1, feeding the lepidolite flotation tailings into a high-frequency screen for pre-screening, S2, feeding the undersize material of the high-frequency screen obtained in the S1 into a 120-mesh drum screen for precise screening, the inclination angle and the rotating speed of the drum screen are controlled to be 4-6 degrees and 10-16 revolutions per minute respectively, the feeding concentration is maintained to be within the range of 20-25%, and the content of materials with the size of-140 meshes on the screen accounts for 17-25%; s3, controlling oversize materials of the cylinder screen in the step S2 to enter a hydrocyclone for grading, wherein overflow is a slender stone product; s4, graded sand setting products of underflow in the step S3 are fed into an ore pulp stirring barrel, and a flotation reagent and ore pulp are fully and evenly mixed; and S5, feeding the ore pulp which is fully and uniformly mixed in the step S4 into roughing operation, wherein a foam product is a lepidolite rough concentrate product. According to the method, through organic combination of multi-stage screening classification, flotation and magnetic separation, accurate control over the iron content and the particle size of the product is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of ore dressing, in particular to a process for preparing low-iron photovoltaic feldspar from lithium mica flotation tailings. Background Art

[0002] With the rapid development of the photovoltaic industry, the quality requirements for photovoltaic glass raw materials are constantly increasing. As one of the important raw materials for photovoltaic glass, the iron content and particle size distribution of feldspar directly affect the transmittance and melting quality of photovoltaic glass. At present, the industrial requirement for feldspar for photovoltaics is that the Fe2O3 content must be controlled below 200ppm. At the same time, in order to ensure the uniformity of glass melting, there are also strict requirements on the particle size of feldspar. In the selection of feldspar raw materials, the tailings after lithium mica ore dressing are an ideal source of photovoltaic feldspar raw materials because of their high feldspar content and good whiteness. However, due to the deep dissociation and grinding in the lithium mica dressing process, the embedded particle size of feldspar and iron minerals in the tailings is fine, which increases the difficulty of subsequent iron removal.

[0003] In the prior art, some ore dressing plants use a multi-stage classification-magnetic separation combined process to prepare photovoltaic feldspar. Although this method can achieve the purpose of fineness, a large amount of useful minerals are lost in the process. Not only does it require complex processes such as pre-slurrying and desludging, but it also has a low iron removal rate, a long process flow and high costs. Due to the complex occurrence of iron minerals in lithium mica tailings, including various forms such as embedded iron, secondary iron and mechanically mixed iron, and the existing process often only uses a single iron removal method, it is difficult to achieve effective separation of iron minerals in different occurrence states. At the same time, excessive grinding for the purpose of iron removal makes it difficult to control the fineness of the product, and it is impossible to meet the requirements of photovoltaic glass production for the particle size of raw materials. Therefore, it is of great significance to develop an efficient ore dressing process that can simultaneously achieve iron content control and particle size compliance to improve the comprehensive utilization value of lithium mica tailings. Summary of the invention

[0004] In view of the shortcomings of the above-mentioned prior art, such as the loss of a large amount of useful minerals in the process of preparing photovoltaic feldspar, low iron removal rate, and inability to meet the requirements of photovoltaic glass production on raw material particle size, the applicant provides a reasonable and effective process for preparing low-iron photovoltaic feldspar from lithium mica flotation tailings, which can achieve an efficient mineral processing process with controlled iron content and particle size meeting the standards.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A process for preparing low-iron photovoltaic feldspar from lithium mica flotation tailings, comprising the following steps: step S1, feeding the lithium mica flotation tailings obtained in the lithium mica beneficiation main process into a high-frequency screen for pre-screening, step S2, feeding the material under the high-frequency screen obtained in step S1 into a 120-mesh drum screen for precise screening, wherein the inclination angle and the rotation speed of the drum screen are respectively controlled at 4°-6° and 10-16 rpm, the feed concentration is maintained in the range of 20%-25%, and the material on the screen is -140 The mesh content accounts for 17-25%; step S3, controlling the material on the cylindrical screen in step S2 to enter the hydrocyclone for classification, and the overflow is the slender stone product; step S4, feeding the classified sand settling product of the bottom flow in step S3 into the slurry mixing barrel, maintaining the slurry concentration in the mixing barrel to 38-40% by adding water, adding the lepidolite collector to the slurry, and fully mixing the flotation agent and the slurry; step S5, feeding the slurry fully mixed in step S4 into the roughing operation, and the foam production The product is a lithium mica rough concentrate product; step S6, the tailings of the roughing operation of step S5 are continuously fed into the scavenging operation, the scavenging time is 6-8 minutes, and the foam product is a scavenging concentrate product, which is incorporated into the lithium mica rough concentrate product; step S7, the high-frequency screen material of step S1 and all the lithium mica rough concentrate products of step S6 are fed into the grinding system of the lithium mica beneficiation main process for regrinding, and the grinding fineness is controlled to be greater than 95% at -60 mesh; step S8, the scavenging operation of step S6 The tailings are continuously fed into the magnetic separation operation to remove mechanically mixed iron and obtain weakly magnetic and non-magnetic materials; step S9, the weakly magnetic and non-magnetic materials in step S8 are then fed into high gradient magnetic separation to remove secondary iron and obtain low-iron photovoltaic feldspar products; step S10, the material re-ground by the grinding system in step S7 enters the flotation process of the main process of lithium mica beneficiation to recover the lithium mica concentrate; step S11, the slender stone obtained in steps S2 and S3 is incorporated into the filtration system to obtain the final slender stone product.

[0007] As a further improvement of the above technical solution:

[0008] In step S1, a 0.4×0.4 mm high frequency screen is used, the feed concentration is controlled within the range of 25%-30%, the vibration frequency and amplitude are controlled within the range of 1080-1500 times / min and 3-5 mm, respectively, to ensure that the content of -70 mesh under the screen is not less than 90%.

[0009] In step S3, the hydrocyclone adopts tangential feeding mode, the feeding pressure is controlled at 0.8-0.12MPa, the feeding concentration is 15%-20%, the overflow port and the underflow port diameters are 80-100mm and 40-45mm respectively, the overflow removal part is -200 mesh, and the yield is 5-8%.

[0010] The roughing time in the roughing operation of step S5 is 8-12 minutes, the speed of the flotation machine is 1800-1930 rpm, and the aeration volume is 0.4-0.6m3 / minute, and the flotation temperature is controlled at 18-25℃.

[0011] The flotation process of steps S5 and S6 adopts: flotation concentration 40%, roughing doping collector 400g / t, polyacrylamide 8g / t, scavenging doping collector 200g / t; roughing scraping foam for 8 minutes, scavenging scraping foam for 6 minutes.

[0012] Step S7 further comprises: step S7-1, the high-frequency screen material of step S1 and all the lithium mica coarse concentrate products of step S6 enter the first stage cyclone, the overflow product of the first stage cyclone enters the second stage cyclone, the overflow product of the second stage cyclone is the slender stone product, and the bottom flow product enters step S7-2 for operation; step S7-2, the bottom flow product of the first stage cyclone in step S7-1 passes through a first stage rod mill and enters a spiral classifier, the bottom flow return sand of the spiral classifier enters the second stage rod mill and then enters step S7-3, the overflow product of the spiral classifier enters the second stage The first-stage cyclone, spiral classifier and hydrocyclone are used together for grinding and classification; step S7-3, the underflow sediment of the spiral classifier in step S7-2 enters the high-frequency vibrating screen after passing through the rod mill, the product under the high-frequency vibrating screen enters the second-stage cyclone, and the product on the screen returns to the first-stage rod mill in step S7-2 for operation; step S7-4, the second-stage cyclone collects the overflow product of the first-stage cyclone in step S7-1, the overflow of the spiral classifier in step S7-2, and the product under the high-frequency vibrating screen in step S7-3, and then enters step S10 for operation.

[0013] In the magnetic separation operation of step S8, weak magnetic separation is performed by a wet permanent magnetic drum magnetic separator, the magnetic field strength is 800-1500 Gauss, the feed concentration is 25%-30%, and the rotation speed is 28-32 rpm.

[0014] In step S9, the magnetic field strength of the high gradient magnetic separation is 12000-15000 Gauss, the feed concentration is 20%-25%, a mesh matrix with a gap of 2.5-3.0 mm is used, and the flushing water pressure is 0.2-0.25 MPa.

[0015] Step S9 further includes: the magnetic separation product obtained by the high gradient magnetic separator in step S9 enters the magnetic cyclone, and the dehydrated product of the magnetic cyclone returns to step S7 and enters the main process of lithium mica beneficiation after being processed by the grinding system.

[0016] Step S10 further comprises: step S10-1, the product obtained after re-grinding in the grinding system in step S10 is put into the flotation stirring barrel, and the flotation collector and inhibitor are added to make the reagent and the slurry fully and evenly mixed to enter the roughing operation, and the foam product is the lepidolite roughing concentrate product, and the other part is the roughing tailings product; step S10-2, the roughing concentrate product in step S10-1 is fed to the selection I operation, and the foam product is the selection I concentrate product, and the other part is the selection I intermediate product; step S10-3, the selection I concentrate product in step S10-2 is further fed to the selection II operation, and the foam product is the lepidolite concentrate product, and the other part is the selection II intermediate product; step S10-4, the selection II intermediate product in step S10-3 and the step S10-1 are mixed. The products of the medium and rougher concentrates are combined to carry out the concentration I operation to form a closed-circuit operation; step S10-5, the rougher tailings in step S10-1 are continuously fed into the scavenging I operation, and the obtained foam product is the medium ore product of scavenging I, and the other part is the tailings product of scavenging I; step S10-6, the scavenging I concentrate product obtained in step S10-5 and the concentration I medium ore product obtained in step S10-2 are combined and returned to the roughing operation to form a large flotation closed circuit; step S10-7, the scavenging I tailings product obtained in step S10-5 is continuously fed into the scavenging II operation, and the obtained foam product is the scavenging II concentrate product, and the other part is the slender stone product; step S10-8, the scavenging II concentrate product obtained in step S10-7 and the rougher tailings product in step S10-1 are combined to carry out the scavenging I operation.

[0017] The low-iron photovoltaic feldspar product produced in step S9 contains Fe2O3 less than 150 ppm and has a fineness of -140 mesh less than 20%.

[0018] The beneficial effects of the present invention are as follows:

[0019] (1) The present invention adopts a process combining multi-stage screening with flotation and magnetic separation to specifically treat iron minerals in different occurrence states. High-frequency screening, cylindrical screen and cyclone classification create good conditions for flotation and magnetic separation. Flotation removes iron from lithium mica, and two-stage magnetic separation removes mechanical iron and secondary iron. The Fe2O3 content of the final product is stably controlled below 150ppm.

[0020] (2) The present invention optimizes the screening parameters to ensure that the -140 mesh content is controlled within 20%. The inclination angle and rotation speed of the cylindrical screen are optimized to improve the classification accuracy, and the cyclone de-fines the particle size distribution of the magnetic separation material to ensure the stability of the final product particle size.

[0021] (3) The present invention adopts a combined process of screening-flotation-magnetic separation to reduce process steps and reduce production costs. After optimization, the parameters of each process are well connected and coordinated to ensure that the production process is stable and controllable, the operation is simple, and it is easy to industrialize.

[0022] (4) The present invention reduces mineral loss in each link through precise classification control. The high-frequency screen material and flotation foam concentrate can be recycled and reselected, and the cylindrical screen material overflowed by the cyclone can be used as a slender stone product, thereby improving the comprehensive utilization efficiency of resources.

[0023] (5) The present invention adopts a spiral classifier and a hydrocyclone for grinding and classification, and two groups of hydrocyclones are used for particle size control. Through the technological innovation of the three equipments of spiral classifier, hydrocyclone and high-frequency vibrating screen, the particle size of the grinding product is guaranteed, which provides good conditions for the subsequent flotation process of lithium mica. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0025] Figure 2 This is a schematic diagram of an implementation of step S7 of the present invention. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] Reference Figure 1 As shown, Figure 1 The main process of lithium mica beneficiation shown in the figure is a component of the lithium mica beneficiation process. The lithium mica beneficiation process obtains lithium mica flotation tailings through a flotation process. The process method for preparing low-iron photovoltaic feldspar from lithium mica flotation tailings of the present invention comprises the following steps:

[0028] Step S1, the lepidolite flotation tailings obtained in the main process of lepidolite beneficiation are sent to a high-frequency screen for pre-screening. This step uses a 0.4×0.4mm high-frequency screen, the feed concentration is controlled within the range of 25%-30%, the vibration frequency and amplitude are controlled within 1080-1500 times / minute and 3-5mm, respectively, to ensure that the content of -70 mesh under the screen is not less than 90%.

[0029] Step S2, the material under the high-frequency screen obtained in step S1 is then put into a 120-mesh drum screen for precise screening, the inclination angle and rotation speed of the drum screen are controlled at 4°-6° and 10-16 rpm respectively, the feed concentration is maintained in the range of 20%-25%, the content of the material on the screen - 140 mesh accounts for 17-25%, and the material under the screen is a slender stone product.

[0030] Step S3, control the material on the cylindrical screen in step S2 to enter the 250 type hydrocyclone for classification. The cyclone adopts a tangential feeding method, the feeding pressure is controlled at 0.8-0.12MPa, the feeding concentration is 15%-20%, the overflow port and the underflow port diameters are 80-100mm and 40-45mm respectively, the overflow removal part is -200 mesh, the yield is 5-8%, and this overflow is a slender stone product.

[0031] Step S4, feeding the classified sand settling product of the bottom flow in step S3 into the slurry mixing tank, maintaining the slurry concentration in the mixing tank to 38-40% by adding water, adding lepidolite collector to adjust the slurry, and fully mixing the flotation agent and the slurry.

[0032] Step S5, feeding the slurry mixed thoroughly in step S4 into the roughing operation, wherein the roughing time is 8-12 minutes, the flotation machine speed is 1800-1930 rpm, and the aeration volume is 0.4-0.6m 3 / minute, the flotation temperature is controlled at 18-25℃, and the foam product is a coarse concentrate of lithium mica.

[0033] Step S6, the tailings from the roughing operation in step S5 are continuously fed into the scavenging operation, the scavenging time is 6-12 minutes, and the foam product is the scavenging concentrate product, which is incorporated into the lepidolite rough concentrate product.

[0034] Step S7, feeding the high-frequency screened material of step S1 and all the coarse concentrate products of lepidolite in step S6 into the grinding system of the main process of lepidolite beneficiation for regrinding, and the grinding fineness is controlled to be greater than 95% at -60 mesh.

[0035] Optionally, refer to Figure 2 As shown, step S7 further includes:

[0036] Step S7-1, the high-frequency screen material of step S1 and all the lithium mica coarse concentrate products of step S6 enter the first-stage cyclone, the overflow product of the first-stage cyclone enters the second-stage cyclone, the overflow product of the second-stage cyclone is the slender stone product, and the bottom flow product enters step S7-2 for operation;

[0037] Step S7-2, the underflow product of the first-stage cyclone in step S7-1 passes through a first-stage rod mill and then enters a spiral classifier, the underflow return sand of the spiral classifier enters the second-stage rod mill and then enters step S7-3, the overflow product of the spiral classifier enters the second-stage cyclone, and the spiral classifier and the hydrocyclone are used together for grinding and classification;

[0038] Step S7-3, the underflow sediment of the spiral classifier in step S7-2 passes through the rod mill and enters the high-frequency vibrating screen, the product under the high-frequency vibrating screen enters the second-stage cyclone, and the product on the screen returns to the first-stage rod mill in step S7-2 for operation;

[0039] Step S7-4, the second-stage cyclone collects the overflow product of the first-stage cyclone in step S7-1, the overflow of the spiral classifier in step S7-2, and the product under the high-frequency vibration screen in step S7-3, and then enters step S10 for operation.

[0040] The present invention adopts a spiral classifier and a hydrocyclone for grinding and classification, and two groups of hydrocyclones are used for particle size control. Through the technological innovation of the three equipments of the spiral classifier, the hydrocyclone and the high-frequency vibrating screen, the particle size of the grinding product material is guaranteed, which provides good conditions for the subsequent flotation process of lithium mica. By changing the combination of the three grinding and classification equipments of the spiral classifier, the hydrocyclone and the high-frequency vibrating screen, the optimal state of the grinding system is achieved, thereby improving the grade of lithium mica concentrate and improving production efficiency.

[0041] Step S8, the tailings from the scavenging operation in step S6 are continuously fed into the magnetic separation operation, and weak magnetic separation is performed by a wet permanent magnetic drum magnetic separator, with a magnetic field strength of 800-1500 Gauss, a feed concentration of 25%-30%, and a rotation speed of 28-32 rpm, to remove mechanically mixed iron and obtain weakly magnetic and non-magnetic materials.

[0042] Step S9, feed the weakly magnetic and non-magnetic materials in step S8 into a high gradient magnetic separator for high gradient magnetic separation, with a magnetic field strength of 12000-15000 Gauss, a feed concentration of 20%-25%, a mesh matrix with a gap of 2.5-3.0 mm, and a flushing water pressure of 0.2-0.25 MPa to remove secondary iron and obtain high-quality low-iron photovoltaic feldspar products.

[0043] Optionally, step S9 further includes: the magnetic separation product obtained by high gradient magnetic separator in step S9 enters the magnetic cyclone, and the dehydrated product of the magnetic cyclone returns to step S7 and enters the main process of lithium mica beneficiation after being processed by the grinding system.

[0044] Step S10: the material re-ground by the grinding system in step S7 enters the flotation process of the main process of lepidolite beneficiation to recover the lepidolite concentrate.

[0045] Optionally, step S10 further includes:

[0046] Step S10-1, the product obtained after re-grinding in the grinding system in step S10 enters the flotation stirring barrel, adds the flotation collector and the inhibitor, and fully stirs the reagent and the slurry to enter the roughing operation, the foam product is the lepidolite roughing concentrate product, and the other part is the roughing tailings product;

[0047] Step S10-2, feeding the roughing concentrate product in step S10-1 to the concentration I operation, the foam product is the concentration I concentrate product, and the other part is the concentration I middling product;

[0048] Step S10-3, the concentrate product of Concentrated I in step S10-2 is continuously fed to the Concentrated II operation, the foam product is the lithium mica concentrate product, and the other part is the Concentrated II middling product;

[0049] Step S10-4, combining the mineral products from the concentration II in step S10-3 with the roughing concentrate products from step S10-1 to perform concentration I operation, forming a closed-loop operation;

[0050] Step S10-5, the roughing tailings in step S10-1 are continuously fed into the scavenging I operation, and the obtained foam product is the scavenging I roughing product, and the other part is the scavenging I tailings product;

[0051] Step S10-6, combining the scavenging I concentrate product obtained in step S10-5 and the beneficiation I middling product obtained in step S10-2 and returning them to the roughing operation to form a large flotation closed circuit;

[0052] Step S10-7, the scavenging I tailings product obtained in step S10-5 is continuously fed to the scavenging II process, and the obtained foam product is the scavenging II concentrate product, and the other part is the slender stone product;

[0053] Step S10-8, the scavenging II concentrate product obtained in step S10-7 and the roughing tailings product in step S10-1 are combined to perform scavenging I operation.

[0054] Step S11, the slender stone obtained in steps S2 and S3 is incorporated into a filtration system to obtain a final slender stone product.

[0055] The process for preparing low-iron photovoltaic feldspar from lithium mica flotation tailings provided by the present invention realizes precise control of the iron content and particle size of the product through the organic combination of multi-stage screening and classification with flotation and magnetic separation. The final low-iron photovoltaic feldspar product of the present invention contains less than 150ppm of Fe2O3 and a fineness of -140 mesh is less than 20%.

[0056] In step S1, high-frequency vibration is used to effectively prevent the screen from being blocked, improve the screening efficiency, ensure that the content of the undersize -70 mesh is not less than 90%, and the oversize material is returned to the lithium mica flotation process. The purpose of high-frequency screening is to remove the coarse particles that are not fully dissociated and create conditions for subsequent separation.

[0057] In step S2, by adjusting the inclination and rotation speed of the drum screen, the rolling and screening effect of the material in the drum screen is utilized to achieve accurate grading of the material, control the content of the material above the screen -140 mesh to be less than 20%, and the material below the screen is incorporated into the cyclone feed. The appropriate feed concentration can avoid screen blockage, ensure the grading effect, and lay the foundation for the particle size index of the final product.

[0058] In step S3, the centrifugal force is used to separate particles, remove part of the -200 mesh material, and adjust the subsequent flotation concentration to maintain the underflow concentration at 45%-50%. The optimization of the cyclone structural parameters and operating parameters not only achieves the removal of -200 mesh mud and sand, but also achieves the purpose of adjusting the flotation concentration.

[0059] The high-concentration flotation and sufficient stirring in the stirring barrel in steps S4-S6 and S7-S9 ensure the effective contact between the reagent and the mineral surface, and the flotation process parameters improve the separation effect of embedded iron; the two-stage magnetic separation adopts progressive magnetic field intensity to specifically process iron in different occurrence states, and the reasonable feed concentration and equipment parameter optimization ensure the magnetic separation effect.

[0060] In order to verify the effect of the present invention and seek the optimal process conditions in the flotation process of steps S5 and S6, the process method of the present invention was subjected to the following six tests 1# to 6# as shown in Table 1.

[0061] Table 1

[0062]

[0063] Among them, the 1# group test adopted: screening -45 mesh + 160 mesh, the obtained material -140 mesh accounted for 17.75%, and this material was then subjected to a coarse and a sweep flotation process, with a flotation concentration of 38%, a collector (6-1-A) of 400g / t was added in the coarse selection, and a collector of 200g / t was added in the sweep selection; the rough selection was scraped for 4 minutes, and the sweep selection was scraped for 3 minutes.

[0064] The 2# group test adopted: screening -45 mesh + 160 mesh, the obtained material -140 mesh accounted for 17.75%, and this material was then subjected to a coarse and scavenging flotation process, with a flotation concentration of 40%, a collector (6-1-A) of 400g / t was added in the coarse selection, and a collector of 200g / t was added in the scavenging selection; the rough selection was scraped for 4 minutes, and the scavenging was scraped for 3 minutes.

[0065] The 3# group test adopted: screening -45 mesh + 160 mesh, the obtained material -140 mesh accounted for 17.75%, and this material was then subjected to a roughing and sweeping flotation process, with a flotation concentration of 40%, 400g / t of collector (kx-236) was added in the roughing, and 200g / t of collector was added in the sweeping; the roughing was scraped for 4 minutes, and the sweeping was scraped for 3 minutes.

[0066] The 4# group test adopted: screening -45 mesh + 160 mesh, the obtained material -140 mesh accounted for 17.75%, and this material was then subjected to a coarse and scavenging flotation process, with a flotation concentration of 40%. In the coarse selection, 400g / t of collector (6-1-A) and 8g / t of polyacrylamide (PAM) were added, and in the scavenging selection, 200g / t of agent was added; the rough selection was scraped and foamed for 4 minutes, and the scavenging was scraped and foamed for 3 minutes.

[0067] The 5# group test adopted: screening -45 mesh + 160 mesh, the obtained material -140 mesh accounted for 17.75%, and this material was then subjected to a coarse and a scavenging flotation process, with a flotation concentration of 38%, a collector (6-1-A) of 450g / t was added in the coarse selection, and a collector of 150g / t was added in the scavenging selection; the rough selection was scraped for 5 minutes, and the scavenging was scraped for 3 minutes.

[0068] The 6# group test adopted: screening -45 mesh + 160 mesh, the obtained material -140 mesh accounted for 17.75%, and this material was then subjected to a coarse and scavenging flotation process, with a flotation concentration of 38%. In the coarse selection, 450g / t of collector (6-1-A) and 8g / t of polyacrylamide (PAM) were added, and in the scavenging selection, 150g / t of agent was added; the rough selection was scraped and foamed for 5 minutes, and the scavenging was scraped and foamed for 3 minutes.

[0069] From the test results of Group 1 to Group 6 above, it can be seen that the content of -140 mesh in the present invention is controlled within 20%, the content of Fe2O3 in the product is stably controlled below 150ppm, the effect after optimization is stable, and the flotation process conditions used in Group 4 are the best. According to actual production conditions, the flotation time of industrial production is generally adjusted to twice the flotation time in the test, so the flotation time in the above test is adjusted twice in actual production.

[0070] The present invention adopts a process combining multi-stage screening with flotation and magnetic separation to specifically process iron minerals in different occurrence states. High-frequency screening, cylindrical screen and cyclone classification create good conditions for flotation and magnetic separation. Flotation removes iron from lithium mica, and two-stage magnetic separation removes mechanical iron and secondary iron. The Fe2O3 content of the final product is stably controlled below 150ppm.

[0071] The present invention ensures that the -140 mesh content is controlled within 20% by optimizing the screening parameters. The inclination angle and rotation speed of the cylindrical screen are optimized to improve the classification accuracy, and the particle size distribution of the magnetic separation material is improved in combination with the de-fine effect of the cyclone, so as to ensure the stability of the particle size of the final product.

[0072] The present invention adopts a combined process of screening-flotation-magnetic separation to reduce process links and reduce production costs. After optimization, the process parameters are well connected and coordinated to ensure a stable and controllable production process, simple operation, and easy industrial production.

[0073] The present invention reduces mineral loss in each link through precise classification control. The high-frequency screen material and flotation foam concentrate can be recycled and reselected, and the cylindrical screen material overflowed by the cyclone can be used as a slender stone product, thereby improving the comprehensive utilization efficiency of resources.

[0074] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings, characterized in that: The method comprises the following steps: step S1, feeding the lepidolite flotation tailings obtained in the main process of lepidolite beneficiation into a high-frequency screen for pre-screening; step S2, feeding the material under the high-frequency screen obtained in step S1 into a 120-mesh drum screen for precise screening, wherein the inclination angle and the rotation speed of the drum screen are respectively controlled at 4°-6° and 10-16 rpm, the feed concentration is maintained within the range of 20%-25%, and the content of the material on the screen-140 mesh accounts for 17-25%; step S3, controlling In step S2, the material on the cylindrical screen enters the hydrocyclone for classification, and the overflow is the slender stone product; in step S4, the classified sand settling product of the bottom flow in step S3 is fed into the slurry mixing barrel, and the slurry concentration in the mixing barrel is maintained at 38-40% by adding water, and the lepidolite collector is added to adjust the slurry, so that the flotation agent and the slurry are fully mixed; in step S5, the slurry after being fully mixed in step S4 is fed into the roughing operation, and the foam product is the lepidolite coarse concentrate product; in step S6, the slurry after being fully mixed in step S7 is fed into the roughing operation, and the foam product is the lepidolite coarse concentrate product; Step S6, continue to feed the tailings of the roughing operation of step S5 into the scavenging operation, the scavenging time is 6-8 minutes, and the foam product is the scavenging concentrate product, which is incorporated into the lithium mica rough concentrate product; step S7, feed the high-frequency screen material of step S1 and all the lithium mica rough concentrate products of step S6 into the grinding system of the lithium mica beneficiation main process for regrinding, and the grinding fineness is controlled to be greater than 95% at -60 mesh; step S8, continue to feed the tailings of the scavenging operation of step S6 into the magnetic separation operation, remove the mechanically mixed iron, and obtain weak magnetic and non-magnetic materials; step S9, the weak magnetic and non-magnetic materials of step S8 are then fed into high-gradient magnetic separation to remove secondary iron and obtain low-iron photovoltaic feldspar products; step S10, the material after regrinding in the grinding system in step S7 enters the flotation process of the lithium mica beneficiation main process to recover the lithium mica concentrate; step S11, the slender stone obtained in steps S2 and S3 is incorporated into the filtration system to obtain the final slender stone product.

2. The process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings according to claim 1, characterized in that: In step S1, a 0.4×0.4 mm high-frequency screen is used, the feed concentration is controlled within the range of 25%-30%, the vibration frequency and amplitude are controlled within the range of 1080-1500 times / min and 3-5 mm, respectively, to ensure that the content under the sieve -70 mesh is not less than 90%.

3. The process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings according to claim 1, characterized in that: In step S3, the hydrocyclone adopts a tangential feeding method, the feeding pressure is controlled at 0.8-0.12 MPa, the feeding concentration is 15%-20%, the overflow port and the underflow port diameters are 80-100 mm and 40-45 mm respectively, the overflow removal part is -200 mesh, and the yield is 5-8%.

4. The process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings according to claim 1, characterized in that: The roughing time in the roughing operation of step S5 is 8-12 minutes, the speed of the flotation machine is 1800-1930 rpm, the aeration volume is 0.4-0.6 m³ / min, and the flotation temperature is controlled at 18-25°C.

5. The process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings according to claim 1, characterized in that: The flotation process of steps S5 and S6 adopts: flotation concentration 40%, roughing doping collector 400g / t, polyacrylamide 8g / t, scavenging doping collector 200g / t; roughing scraping foam for 8 minutes, scavenging scraping foam for 6 minutes.

6. The process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings according to claim 1, characterized in that: Step S7 further comprises: step S7-1, the high-frequency screen material of step S1 and all the lithium mica coarse concentrate products of step S6 enter the first stage cyclone, the overflow product of the first stage cyclone enters the second stage cyclone, the overflow product of the second stage cyclone is the slender stone product, and the bottom flow product enters step S7-2 for operation; step S7-2, the bottom flow product of the first stage cyclone in step S7-1 passes through a first stage rod mill and enters a spiral classifier, the bottom flow return sand of the spiral classifier enters the second stage rod mill and then enters step S7-3, the overflow product of the spiral classifier enters the second stage The first-stage cyclone, spiral classifier and hydrocyclone are used together for grinding and classification; step S7-3, the underflow sediment of the spiral classifier in step S7-2 enters the high-frequency vibrating screen after passing through the rod mill, the product under the high-frequency vibrating screen enters the second-stage cyclone, and the product on the screen returns to the first-stage rod mill in step S7-2 for operation; step S7-4, the second-stage cyclone collects the overflow product of the first-stage cyclone in step S7-1, the overflow of the spiral classifier in step S7-2, and the product under the high-frequency vibrating screen in step S7-3, and then enters step S10 for operation.

7. The process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings according to claim 1, characterized in that: In the magnetic separation operation of step S8, weak magnetic separation is performed by a wet permanent magnetic drum magnetic separator, the magnetic field strength is 800-1500 Gauss, the feed concentration is 25%-30%, and the rotation speed is 28-32 rpm.

8. The process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings according to claim 1, characterized in that: In step S9, the magnetic field strength of the high gradient magnetic separation is 12000-15000 Gauss, the feed concentration is 20%-25%, a mesh matrix with a gap of 2.5-3.0 mm is used, and the flushing water pressure is 0.2-0.25 MPa.

9. The process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings according to claim 1, characterized in that: Step S9 further includes: the magnetic separation product obtained by the high gradient magnetic separator in step S9 enters the magnetic cyclone, and the dehydrated product of the magnetic cyclone returns to step S7 and enters the main process of lithium mica beneficiation after being processed by the grinding system.

10. The process for preparing low-iron photovoltaic feldspar from lepidolite flotation tailings according to claim 1, characterized in that: Step S10 further comprises: step S10-1, the product obtained after re-grinding in the grinding system in step S10 is put into the flotation stirring barrel, and the flotation collector and inhibitor are added to make the reagent and the slurry fully and evenly mixed to enter the roughing operation, and the foam product is the lepidolite roughing concentrate product, and the other part is the roughing tailings product; step S10-2, the roughing concentrate product in step S10-1 is fed to the selection I operation, and the foam product is the selection I concentrate product, and the other part is the selection I intermediate product; step S10-3, the selection I concentrate product in step S10-2 is further fed to the selection II operation, and the foam product is the lepidolite concentrate product, and the other part is the selection II intermediate product; step S10-4, the selection II intermediate product in step S10-3 and the step S10-1 are mixed. The products of the medium and rougher concentrates are combined to carry out the concentration I operation to form a closed-circuit operation; step S10-5, the rougher tailings in step S10-1 are continuously fed into the scavenging I operation, and the obtained foam product is the medium ore product of scavenging I, and the other part is the tailings product of scavenging I; step S10-6, the scavenging I concentrate product obtained in step S10-5 and the concentration I medium ore product obtained in step S10-2 are combined and returned to the roughing operation to form a large flotation closed circuit; step S10-7, the scavenging I tailings product obtained in step S10-5 is continuously fed into the scavenging II operation, and the obtained foam product is the scavenging II concentrate product, and the other part is the slender stone product; step S10-8, the scavenging II concentrate product obtained in step S10-7 and the rougher tailings product in step S10-1 are combined to carry out the scavenging I operation.

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