Method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings

Abstract

The invention relates to a method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings. The method is characterized by comprising the following steps: (1) grinding pegmatite type lepidolite tailings, and screening to obtain mineral particles with the particle size of less than or equal to 0.35 mm; (2) sequentially carrying out medium magnetic separation, high-intensity magnetic separation and high-intensity magnetic separation on the-0.35 mm minerals to obtain magnetic separation fine sand and magnetic separation tailings; (3) scrubbing the magnetic separation fine sand to obtain desliming fine sand with higher purity; (4) the desliming fine sand is subjected to three-section flotation, the ore pulp concentration of first-section flotation is 35%-40%, H2SO4 serves as a pH adjusting agent, the pH is adjusted to 2-5, and mixed amine serves as a collecting agent of 0.10-0.15 kg / t; the ore pulp concentration of the second-stage flotation is 25%-30%, H2SO4 is used as a pH regulator, the pH is regulated to be 1-3, and an anion and cation collecting agent is 0.10-0.15 kg / t; the ore pulp concentration of the third-section flotation is 25%-30%, H2SO4 is used as a pH regulator, the pH is regulated to 1-3, the use amount of an anion and cation collecting agent is 1.25-2.25 kg / t, and feldspar and quartz fine sand are obtained. The method has the advantages that the prepared quartz fine sand meets the index requirements of quartz for optical glass or photovoltaic glass, and meanwhile, feldspar products for high-whiteness glaze and feldspar products for float glass are obtained.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology and relates to a method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings. Background Technology

[0002] Lepidolite is a major mineral raw material for lithium extraction in my country and is widely used in new energy, aerospace, and other fields. my country's lepidolite mines are mainly distributed in the Nanling region, particularly in Jiangxi and Hunan provinces, and are primarily separated and enriched through flotation. my country produces over 1200 tons of lepidolite tailings annually, and their resource utilization is an important way to promote the sustainable development of the lepidolite industry.

[0003] In industrial development, feldspar and quartz are generally considered gangue minerals and are incorporated into lepidolite tailings along with the processing flow. Quartz is an important non-metallic mineral and an irreplaceable fundamental material in the development of my country's strategic emerging industries and pillar industries. Feldspar is a typical framework-structured alkali metal aluminum silicate mineral with stable chemical properties and is widely used in the glass, ceramics, and other building materials industries. Purifying lepidolite tailings to produce refined quartz sand and feldspar not only provides raw materials for the glass manufacturing, construction, ceramics, and casting industries, but also reduces environmental pollution caused by tailings accumulation, protecting the environment while achieving resource reuse.

[0004] Currently, the recovery of lepidolite tailings requires processes such as desliming, grinding, magnetic separation, and flotation. Flotation is the most feasible method for separating feldspar and quartz. Studies have shown that using anionic and cationic collectors can achieve the separation of quartz and feldspar in lepidolite tailings. Anionic collectors activate feldspar within the adsorption active region of amine cationic collectors, resulting in a greater difference in floatability between quartz and feldspar. During the flotation separation process, the entrainment of feldspar and quartz is quite common, causing other minerals besides the target mineral to be floated simultaneously, thus affecting the final grade of both feldspar and quartz.

[0005] Therefore, in order to solve the problems of waste of lithium mica tailings resources and the recovery of quartz and feldspar, there is an urgent need for a novel and efficient process for preparing low-iron quartz sand and high-quality feldspar with high industrial application feasibility and complete technology. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings, characterized by comprising the following steps: (1) Grind the pegmatite-type lepidolite tailings to fully dissociate the tailings particles, and then obtain mineral particles with a particle size ≤0.35mm by screening; (2) Minerals with a diameter of -0.35 mm were subjected to medium magnetic separation, strong magnetic separation and high magnetic separation in sequence. The magnetic separation intensities of medium magnetic separation, strong magnetic separation and high magnetic separation were 0.3~0.5T, 1.0~1.2T and 1.4~1.6T, respectively. Through the stepwise action of the gradient magnetic field, iron-containing minerals with strong magnetic (such as magnetite), medium magnetic and weak magnetic (such as hematite, limonite, etc.) were removed from the minerals in sequence, which significantly reduced the Fe2O3 content in the magnetic concentrate and finally obtained magnetic concentrate and magnetic tailings mainly composed of various types of magnetite. (3) The magnetically separated fine sand is scrubbed to remove fine mud, iron oxide film and other impurities adsorbed on the mineral surface; then it is classified with a screen to remove fine mud impurities, and finally obtains deslimed fine sand with higher purity. (4) The deslimed fine sand is subjected to three-stage flotation. The pulp concentration of the first stage flotation is 35%~40%, H2SO4 is used as pH adjuster to adjust the pH to 2~5, and mixed amines are used as collectors at a dosage of 0.10~0.15 kg / t. The pulp concentration of the second stage flotation is 25%~30%, H2SO4 is used as pH adjuster to adjust the pH to 1~3, and the dosage of anion and cation collectors is 0.10~0.15 kg / t. The pulp concentration of the third stage flotation is 25%~30%, H2SO4 is used as pH adjuster to adjust the pH to 1~3, and the dosage of anion and cation collectors is 1.25~2.25 kg / t. The final feldspar and quartz fine sand obtained (meets the quartz index requirements for optical glass or photovoltaic glass, with Fe2O3 content less than 500 ppm and SiO2 content not less than 99.5%).

[0008] Furthermore, in step (1), the grinding medium is steel balls or steel rods, the medium filling rate is 35%~45%, the grinding concentration is 50%~60%, and the grinding is carried out at a speed of 600~800 r / min for 3~7 min.

[0009] Steel balls or steel rods, as grinding media, have moderate hardness and strong wear resistance, effectively achieving mineral crushing and liberation. A media filling rate of 35% to 45% ensures sufficient contact between the media and minerals during grinding, avoiding insufficient grinding efficiency due to too low a filling rate or excessive energy waste due to too high a filling rate. A grinding concentration of 50% to 60% ensures good fluidity of the minerals in the slurry, while avoiding uneven grinding due to too high a concentration. A grinding time of 3 to 7 minutes and a rotation speed of 600 to 800 r / min are matched to grind the tailings to the target particle size of -0.35 mm in a short time, while avoiding excessive fine mud generated by over-grinding, which increases the difficulty of subsequent processing.

[0010] Furthermore, in step (2), the equipment used for magnetic separation and strong magnetic separation is a vertical ring pulsating high gradient magnetic separator, and the equipment used for high-intensity magnetic separation is an electromagnetic slurry high gradient magnetic separator.

[0011] The vertical ring pulsed high gradient magnetic separator features a high magnetic field gradient, high separation efficiency, and large throughput, making it suitable for separating medium- and strong magnetic minerals. The electromagnetic slurry high gradient magnetic separator can generate a higher intensity magnetic field with good magnetic field stability, effectively capturing weakly magnetic iron-containing minerals. The combined use of the two devices can achieve efficient separation of different magnetic iron minerals.

[0012] Furthermore, the equipment used for scrubbing in step (3) is a scrubbing tank, with a scrubbing concentration of 35%~50%, a rotation speed of 700~1100r / min, and a scrubbing time of 1~15min.

[0013] A scrubbing concentration of 35% to 50% can ensure sufficient friction between mineral particles, while a rotation speed of 700 to 1100 r / min and a scrubbing time of 1 to 15 min can ensure that surface impurities are fully removed, while avoiding excessive mineral breakage due to excessive rotation speed or excessive time.

[0014] Furthermore, in step (3), the screen mesh size is 0.025~0.038mm. This screen mesh size can accurately remove the fine mud (particle size less than 0.025~0.038mm) generated after scrubbing. The fine mud usually contains more iron impurities and gangue minerals. Removing it can improve the grade of the ore and reduce the interference of impurities in the subsequent flotation process.

[0015] Furthermore, the scrubbing-grading operation in step (3) is repeated 1 to 2 times depending on the content of fine mud and surface impurities in the tailings.

[0016] Depending on the content of fine mud and surface impurities in the tailings, 1 to 2 operations can ensure the desliming effect. Too few operations will result in incomplete removal of impurities, while too many operations will increase energy consumption and production costs. A balance between effectiveness and cost must be achieved.

[0017] Furthermore, the equipment used for the first and second stages of flotation is a flotation machine, while the equipment used for the third stage of flotation is a flotation cell.

[0018] Furthermore, in the first stage of flotation, the mixed amine is prepared by mixing dodecylamine polyoxyethylene ether and coconut oil amine in a mass ratio of 1:1 to 1:3; in the second stage of flotation, the anion and cationic collectors are prepared by mixing coconut oil diamine and sodium dodecyl sulfonate in a mass ratio of 1:1 to 1:5; and in the third stage of flotation, the anion and cationic collectors are prepared by mixing coconut oil diamine and sodium dodecyl sulfonate in a mass ratio of 1:1 to 1:5.

[0019] This invention first achieves preliminary mineral liberation through grinding pretreatment, providing a good material basis for subsequent magnetic separation and flotation, and avoiding the impact of improper particle size on the separation effect. Then, through multi-stage gradient magnetic separation, combined with dedicated magnetic separation equipment, iron-containing minerals with different magnetic properties are gradually removed, significantly reducing the iron content in the minerals. This is a key pretreatment step in the preparation of low-iron quartz sand, solving the problem that single magnetic separation cannot completely remove weakly magnetic iron impurities. Next, surface impurities and fine mud are removed through scrubbing and classification, reducing the interference of impurities in the subsequent flotation process, improving separation efficiency and product grade. This step is an important link between magnetic separation and flotation, directly affecting the subsequent flotation effect. Finally, three-stage flotation is used to remove impurities, classify and enrich feldspar, and purify quartz. By adjusting the pH value, pulp concentration, collector type and dosage, and utilizing the synergistic effect of the collector, the difference in floatability between feldspar and quartz is amplified, solving the problem of feldspar and quartz entrainment in traditional flotation methods, and realizing the graded recovery of multiple products.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention adopts a process route of "grinding-multi-stage magnetic separation-scrubbing and desliming-multi-stage flotation". The process design is scientific and reasonable, and each step works together to solve the problems of incomplete removal of iron impurities, mutual entrainment of feldspar and quartz, and low product grade in traditional processes. The process parameters are precise and controllable, and the industrial application is highly feasible. It also avoids the environmental pollution caused by traditional processes such as hydrofluoric acid method, making it green and environmentally friendly, and realizing the efficient resource utilization of lithium mica tailings.

[0021] 2. The quartz concentrate produced by this invention is of excellent quality, with Fe2O3 content below 500ppm and SiO2 content not less than 99.5%, meeting the quartz index requirements for optical glass or photovoltaic glass. At the same time, it can be graded to obtain two high-quality feldspar products: feldspar for high-white glaze and feldspar for float glass, realizing the recovery of multiple products and high added value of tailings resources, and significantly improving the utilization value of lepidolite tailings.

[0022] 3. The mixed amine collector (prepared by mixing dodecylamine polyoxyethylene ether and coconut oil amine in a mass ratio of 1:1 to 1:3) and the anionic and cationic collector (prepared by mixing coconut oil diamine and sodium dodecyl sulfonate in a mass ratio of 1:1 to 1:5) of the present invention are simple to prepare, highly stable, have good selectivity, are easy to disperse, and do not require heating. Based on the synergistic effect between the components, they can effectively modify the surface of mica and feldspar under strongly acidic conditions, making them hydrophobic, thereby achieving the removal of mica and the flotation separation of feldspar and quartz, achieving the effect of reducing the iron content of quartz concentrate and whitening and purifying it. Attached Figure Description

[0023] Figure 1 A schematic diagram of a process for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings. Detailed Implementation

[0024] The following is combined with Figure 1 The present invention will be further described below: A method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings, the specific implementation steps of which are as follows: Example 1

[0025] (1) Grinding of a lithium mica tailings in Yichun, Jiangxi Province, with steel balls as the grinding medium, a medium filling rate of 40% and a grinding concentration of 60%, grinding at 600 r / min for 7 min to fully dissociate the tailings particles, and then obtaining mineral particles with a particle size ≤0.35 mm by screening. (2) For minerals with a diameter of -0.35mm, a vertical ring pulsating high gradient magnetic separator is used for medium and strong magnetic separation. The magnetic field strengths of medium and strong magnetic separation are controlled to be 0.5T and 1.2T respectively. A high-intensity magnetic separation is performed using an electromagnetic slurry high gradient magnetic separator. The magnetic separation intensity of the high-intensity magnetic separation is 1.5T. Through the stepwise action of the gradient magnetic field, strong magnetic (such as magnetite), medium magnetic and weak magnetic iron-containing minerals (such as hematite, limonite, etc.) are removed from the minerals in sequence, which significantly reduces the Fe2O3 content in the magnetic concentrate and finally obtains magnetic concentrate and magnetic tailings mainly composed of various types of magnetite. (3) The magnetically separated fine sand is scrubbed in a scrubbing tank. 10.0 kg / t of 98% H2SO4 is added, and the scrubbing concentration is controlled at 50%. The rotation speed is 700 r / min and the scrubbing time is 10 min to remove impurities and iron oxide film adsorbed on the mineral surface and obtain scrubbing slurry. The Fe2O3 content of the scrubbing fine sand is 0.14%. Then, it is classified with a sieve with a mesh size of 0.038 mm to remove fine mud impurities. The scrubbing-classification is repeated once to finally obtain deslimed fine sand with higher purity. (4) Place the deslimed fine sand in a flotation machine for pulp conditioning. The pulp temperature is 25℃, the pulp concentration is 35%, the rotation speed is 1800 r / min, and 3.7 kg / t of 98% H2SO4 is added to adjust the pH to 2. Add 0.12 kg / t of mixed amine collector (dodecylamine polyoxyethylene ether and coconut oil amine in a mass ratio of 1:2), and the flotation time is 3 min to obtain mica from the lithium mica tailings. Add 2.2 kg / t of 98% H2SO4 to the pulp after removing the mica to adjust the pH to 2. The pulp temperature is 25℃, the rotation speed is 1800 r / min, and anionic and cationic collectors (coconut oil amine) are added. Feldspar froth and reverse flotation were carried out using 3.00 kg / t of amine and sodium dodecyl sulfonate (mass ratio 1:3) for 3 min, yielding feldspar froth and reverse flotation slurry. The reverse flotation slurry was placed in a flotation cell, and 2.2 kg / t of 98% H2SO4 was added to adjust the pH to 2. The slurry temperature was 25℃, the rotation speed was 1800 r / min, and 2.25 kg / t of anionic and cationic collector (cocoa diamine and sodium dodecyl sulfonate mass ratio 1:3) was added. Reverse flotation was carried out, and the froth was scraped for 3-5 min, yielding feldspar froth. The slurry in the flotation cell was dewatered to obtain quartz concentrate, thus fully separating feldspar and quartz in the lepidolite tailings.

[0026] The quartz concentrate obtained in this embodiment has a yield of 13.24%, and the contents of SiO2, Al2O3, and Fe2O3 are 99.79%, 0.56%, and 0.0053%, respectively. Feldspar 1 has a yield of 28.99%, and the contents of Al2O3, Fe2O3, K2O, and Na2O are 17.01%, 0.13%, 4.82%, and 5.93%, respectively. Feldspar 2 has a yield of 13.43%, and the contents of Al2O3, Fe2O3, K2O, and Na2O are 10.25%, 0.052%, 2.64%, and 3.91%, respectively. Comparative Example 1

[0027] Compared with Example 1, the difference in this comparative example is that the magnetically separated refined sand is no longer subjected to a scrubbing operation. The quartz sand yield obtained in this comparative example is 12.44%, with SiO2, Al2O3, and Fe2O3 contents of 98.84%, 0.53%, and 0.0093%, respectively; feldspar 1 yield is 26.30%, with Al2O3, Fe2O3, K2O, and Na2O contents of 17.48%, 0.14%, 4.89%, and 5.98%, respectively; feldspar 2 yield is 14.66%, with Al2O3, Fe2O3, K2O, and Na2O contents of 10.59%, 0.058%, 2.84%, and 4.10%, respectively. Example 2

[0028] (1) A lithium mica tailings in Yichun, Jiangxi Province was ground with steel rods as grinding media. The media filling rate was 35% and the grinding concentration was 60%. The grinding was carried out at 600 r / min for 7 min to fully dissociate the tailings particles. Then, mineral particles with a particle size ≤0.35 mm were obtained by screening. (2) For minerals with a diameter of -0.35 mm, a vertical ring pulsating high gradient magnetic separator is used for medium and strong magnetic separation. The magnetic field strengths of medium and strong magnetic separation are controlled to be 0.4T and 1.0T respectively. An electromagnetic slurry high gradient magnetic separator is used for high-intensity magnetic separation. The magnetic separation intensity of high-intensity magnetic separation is 1.4T. Through the stepwise action of the gradient magnetic field, strong magnetic (such as magnetite), medium magnetic and weak magnetic iron-containing minerals (such as hematite, limonite, etc.) are removed from the minerals in sequence, which significantly reduces the Fe2O3 content in the magnetic concentrate and finally obtains magnetic concentrate and magnetic tailings mainly composed of various types of magnetite. (3) The magnetically separated fine sand is scrubbed in a scrubbing tank. 12.0 kg / t of 98% H2SO4 is added, and the scrubbing concentration is controlled at 50%. The rotation speed is 700 r / min and the scrubbing time is 20 min to remove impurities and iron oxide film adsorbed on the mineral surface and obtain scrubbing slurry. The Fe2O3 content of the scrubbing fine sand is 0.15%. Then, it is classified with a sieve with a mesh size of 0.025 mm to remove fine mud impurities. The scrubbing-classification is repeated once to finally obtain deslimed fine sand with higher purity. (4) Place the deslimed fine sand in a flotation machine for pulp conditioning. The pulp temperature is 25℃, the pulp concentration is 40%, the rotation speed is 1800 r / min, and 2.8 kg / t of 98% H2SO4 is added to adjust the pH to 3. Add 0.15 kg / t of mixed amine collector (dodecylamine polyoxyethylene ether and coconut oil amine in a mass ratio of 1:3), and the flotation time is 3 min to obtain mica from the lithium mica tailings. Add 1.0 kg / t of 98% H2SO4 to the pulp after removing the mica to adjust the pH to 3. The pulp temperature is 25℃, the rotation speed is 1800 r / min, and anionic and cationic collectors (coconut oil amine) are added. Feldspar froth and reverse flotation were carried out using 2.50 kg / t of amine and sodium dodecyl sulfonate (mass ratio 1:2), with froth skimming for 4 min to obtain feldspar froth and reverse flotation slurry. The reverse flotation slurry was placed in a flotation cell, and 1.0 kg / t of 98% H2SO4 was added to adjust the pH to 3. The slurry temperature was 25℃, the rotation speed was 1800 r / min, and 1.80 kg / t of anionic and cationic collector (cocoa diamine and sodium dodecyl sulfonate mass ratio 1:2) was added. Reverse flotation was carried out, with froth skimming for 3-5 min to obtain feldspar froth. The slurry in the flotation cell was dewatered to obtain quartz concentrate, thereby fully separating feldspar and quartz in the lepidolite tailings.

[0029] The quartz concentrate obtained in this embodiment has a yield of 13.64%, and the contents of SiO2, Al2O3, and Fe2O3 are 99.58%, 0.23%, and 0.0056%, respectively; the feldspar 1 has a yield of 25.47%, and the contents of Al2O3, Fe2O3, K2O, and Na2O are 17.03%, 0.12%, 4.59%, and 5.82%, respectively; the feldspar 2 has a yield of 13.58%, and the contents of Al2O3, Fe2O3, K2O, and Na2O are 10.77%, 0.043%, 2.75%, and 4.04%, respectively.

[0030] The above embodiments are only used to explain the principles of the present invention and are not intended to limit the scope of the present invention. Various modifications or substitutions made to the present invention by those skilled in the art without departing from the spirit and principles of the present invention are all within the scope of the claims of the present invention.

Claims

1. A method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings, characterized in that... Includes the following steps: (1) Grind the pegmatite-type lepidolite tailings and then screen them to obtain mineral particles with a particle size ≤0.35mm; (2) The minerals with a diameter of -0.35mm were subjected to medium magnetic separation, strong magnetic separation and high magnetic separation in sequence. The magnetic separation intensities of medium magnetic separation, strong magnetic separation and high magnetic separation were 0.3~0.5T, 1.0~1.2T and 1.4~1.6T respectively, and finally magnetic separation concentrate and magnetic separation tailings were obtained. (3) The magnetically separated fine sand is scrubbed and deslimed to finally obtain deslimed fine sand with higher purity; (4) The deslimed concentrate is subjected to three-stage flotation. The pulp concentration of the first stage flotation is 35%~40%, H2SO4 is used as pH adjuster to adjust the pH to 2~5, and mixed amines are used as collectors at a dosage of 0.10~0.15 kg / t. The pulp concentration of the second stage flotation is 25%~30%, H2SO4 is used as pH adjuster to adjust the pH to 1~3, and the dosage of anion and cation collectors is 0.10~0.15 kg / t. The pulp concentration of the third stage flotation is 25%~30%, H2SO4 is used as pH adjuster to adjust the pH to 1~3, and the dosage of anion and cation collectors is 1.25~2.25 kg / t. The final obtained are feldspar and quartz concentrate.

2. The method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings according to claim 1, characterized in that: In step (1), steel balls or steel rods are used as grinding media, with a media filling rate of 35%~45% and a grinding concentration of 50%~60%, and grinding is carried out at a speed of 600~800 r / min for 3~7 min.

3. The method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings according to claim 1, characterized in that: In step (2), the equipment used for magnetic separation and strong magnetic separation is a vertical ring pulsating high gradient magnetic separator, and the equipment used for high-intensity magnetic separation is an electromagnetic slurry high gradient magnetic separator.

4. The method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings according to claim 1, characterized in that: The equipment used for scrubbing in step (3) is a scrubbing tank, with a scrubbing concentration of 35% to 50%, a rotation speed of 700 to 1100 r / min, and a scrubbing time of 1 to 15 min.

5. The method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings according to claim 1, characterized in that: The sieve mesh size in step (3) is 0.025~0.038mm.

6. The method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings according to claim 1, characterized in that: In step (3), the scrubbing-grading operation is repeated 1 to 2 times depending on the content of fine mud and surface impurities in the tailings.

7. The method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings according to claim 1, characterized in that: The equipment used for the first and second stages of flotation is a flotation machine, while the equipment used for the third stage of flotation is a flotation cell.

8. The method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings according to claim 1, characterized in that: In the first stage of flotation, the mixed amine is prepared by mixing dodecylamine polyoxyethylene ether and coconut oil amine in a mass ratio of 1:1 to 1:3; in the second stage of flotation, the anion and cationic collectors are prepared by mixing coconut oil diamine and sodium dodecyl sulfonate in a mass ratio of 1:1 to 1:5; and in the third stage of flotation, the anion and cationic collectors are prepared by mixing coconut oil diamine and sodium dodecyl sulfonate in a mass ratio of 1:1 to 1:

5.

9. A method for preparing low-iron quartz sand and high-quality feldspar from lepidolite tailings according to any one of claims 1-8, characterized in that: The quartz sand obtained in step (4) meets the quartz index requirements for optical glass or photovoltaic glass, with Fe2O3 content below 500ppm and SiO2 content not less than 99.5%.

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