Sorting process for fine monazite and garnet in coastal sand

Abstract

The invention provides a seaside sand fine monazite and garnet separation process which comprises the following steps: S1, carrying out graded desliming pretreatment on seaside sand in a specific particle size range by adopting a hydrocyclone, and controlling overflow particle size and underflow concentration; s2, magnetic minerals are removed through low-intensity magnetic field magnetic separation, and superfine particles are removed through treatment of a high-frequency vibrating screen after magnetic separation; s3, a composite inhibitor and a collecting agent are added into the pretreated minerals, stirring and size mixing are conducted at the proper temperature, and meanwhile an ultrasonic field is applied; s4, separation is conducted through a two-section table concentrator, and microwave radiation pretreatment is conducted on middlings before re-separation through the second-section table concentrator; and S5, treating the tailing water through a sedimentation tank and then recycling the tailing water. According to the technology, through the synergistic effect of all links, efficient separation of monazite and garnet can be achieved, the recovery rate and grade of separated minerals are high, and the technology has the advantages of being energy-saving and environmentally friendly and is suitable for comprehensive utilization of beach placer resources.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral separation technology, in particular to a process for separating fine monazite and garnet from seashore sand. Background Art

[0002] Seaside sand deposits are a significant source of minerals such as monazite and garnet. Monazite, a key carrier of rare earth elements, is rich in strategic metals such as cerium and lanthanum. In the new energy sector, it is a core raw material for the manufacture of high-performance permanent magnets and electric vehicle battery materials. In the aerospace industry, it can be used to manufacture high-temperature-resistant alloys and precision electronic components. With the global expansion of the new energy industry and the upgrading of high-end manufacturing, market demand is experiencing explosive growth. With a Mohs hardness of 6.5-7.5 and strong chemical stability, garnet is used in the abrasive industry for metal surface polishing and stone cutting. In the building materials industry, it serves as a wear-resistant concrete aggregate and is widely used in industrial flooring, highway construction, and other projects.

[0003] However, monazite and garnet in coastal sands often coexist closely in fine-grained quartz-feldspar and other gangue minerals, posing multiple challenges in their separation. The fineness of the mineral particles increases their specific surface area and leads to similar surface properties, making it difficult for traditional separation methods to accurately separate them based on their physical and chemical differences. Furthermore, the complex coexistence structure results in the intertwining of target minerals and gangue minerals, further complicating separation.

[0004] However, existing separation processes have many limitations. The traditional magnetic separation process is limited by the weak magnetic difference between monazite and garnet, making it difficult to achieve effective separation. The single gravity separation process is prone to low concentrate grade and poor recovery due to the similar sedimentation velocity of fine-grained minerals. Conventional reagent systems have insufficient selective adsorption of fine-grained minerals. When capturing target minerals, a large amount of gangue minerals enter the concentrate due to surface electrostatic adsorption or mechanical inclusions, seriously affecting product quality. In addition, because the surface of fine-grained minerals carries an electric charge, they are prone to agglomeration in the slurry, destroying the particle size differences and surface property differences between particles, further reducing the separation efficiency. Therefore, the development of a separation process that is efficient, environmentally friendly, and suitable for fine-grained paragenetic minerals is of great significance to the comprehensive utilization of coastal sand mine resources. Summary of the Invention

[0005] In view of this, the present invention proposes a process for separating fine monazite and garnet from seaside sand to solve the above problems.

[0006] The technical solution of the present invention is achieved as follows: a process for separating fine monazite and garnet from seashore sand, comprising the following steps: S1. Pre-treating the seashore sand raw material with a particle size range of 0.074-0.15 mm by graded desludging; S2, using weak magnetic field magnetic separation to remove magnetic minerals; S3. Adding a composite inhibitor and a collector to the pretreated mineral, stirring and slurrying at 25-30° C., and applying an ultrasonic field; S4, using two-stage shaking table separation: the first stage shaking table has an inclination of 4-6 degrees, producing monazite coarse concentrate and middlings; the second stage shaking table has an inclination of 2-4 degrees, and the middlings are re-selected to obtain garnet concentrate; S5. Tailings water is recycled after being treated in a sedimentation tank.

[0007] Furthermore, the graded desludging in step S1 adopts a hydrocyclone to control the overflow particle size to be ≤0.020 mm and the underflow concentration to be ≥35 wt%.

[0008] Furthermore, the magnetic field strength of the magnetic separation in step S2 is 0.15-0.3 T, and after the magnetic separation, a high-frequency vibrating screen is performed with a vibration frequency of 200-400 Hz to screen out ultrafine particles below 0.04 mm.

[0009] Furthermore, the composite inhibitor in step S3 is a mixture of modified sodium lignin sulfonate and water glass in a mass ratio of 1:2-3, and the added amount is 800-1200g / t of ore sand; the collector is a compound of sodium oleate, sodium dodecyl sulfate and nano-titanium dioxide in a mass ratio of (4-6):1:(0.4-0.6), and the added amount is 200-400g / t of ore sand.

[0010] Furthermore, the modified sodium lignin sulfonate is alkali lignin treated by oxidation degradation, with a molecular weight of ≤5000Da, and is specifically activated by H2O2 / UV combined activation, with the activation conditions being: H2O2 concentration 2-4wt%, UV wavelength 254nm, and irradiation time 25-35min.

[0011] Furthermore, the slurry concentration after slurry adjustment in step S3 is controlled at 25-30wt%, the stirring time is 10-15 minutes, the ultrasonic field frequency is 30-50kHz, and the power density is 1.0-1.5W / cm 3 , destroy the microbubble groups in the slurry and ensure full contact between the reagent and the mineral.

[0012] Furthermore, in step S4, the stroke of the first section of the shaking table is 12-15 mm, and the stroke frequency is 280-320 times / min; the stroke of the second section of the shaking table is 8-10 mm, and the stroke frequency is 250-280 times / min.

[0013] Furthermore, the ore in the second stage of the shaking table in step S4 is subjected to microwave radiation pretreatment before reselection, with a processing power of 700-900W and an irradiation time of 50-70s, so as to generate micro cracks inside the garnet and promote subsequent reselection dissociation.

[0014] Furthermore, in step S5, the tailings water treatment uses a polymer flocculant with an addition amount of 5-10 g / m3 After precipitation, the supernatant is recycled to the slurry preparation process in step S3. The polymer flocculant is a modified starch flocculant, which is prepared by grafting acrylamide / dimethyldiallyl ammonium chloride copolymerization of cassava starch, with a molecular weight of ≥8×10 6 Da.

[0015] Furthermore, the slurry concentration after slurry adjustment in step S3 is controlled at 25-30 wt %, and the stirring time is 10-15 minutes.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) An integrated process system consisting of graded desludging, weak magnetic separation, ultrasonic field-assisted slurry mixing, and two-stage shaking table separation was employed. Through the synergistic effect of multiple steps, a targeted separation mechanism for fine-grained monazite and garnet in seashore sand was established. This process effectively eliminated the interference of clay minerals and other magnetic impurities, significantly improved the separation efficiency of the target minerals, and produced a high-quality concentrate product.

[0017] (2) Based on the surface chemical properties of minerals, a composite inhibitor and collector system was developed. Combined with microwave pretreatment technology, a highly efficient recovery scheme for monazite and garnet was formed. This technology breaks through the limitations of traditional sorting processes, increasing the recovery rates of monazite and garnet in the raw materials to 93.5% and 85.2%, respectively. This effectively reduces the loss rate of useful minerals and significantly improves the comprehensive utilization level of coastal sand mine resources. DETAILED DESCRIPTION

[0018] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0019] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0020] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0021] Example 1 Raw material preparation: Select a seaside sand raw material with a particle size range of 0.074-0.15mm, of which the monazite content is about 3.2% and the garnet content is about 3.5%.

[0022] Sorting steps: S1. Gradual desludging: Use hydrocyclone for graded desludging, control overflow particle size ≤ 0.020mm, and underflow concentration 38wt%; S2, weak magnetic separation: set the magnetic field strength to 0.5T, and perform high-frequency vibrating screen treatment after magnetic separation, with a vibration frequency of 200Hz to screen out ultrafine particles below 0.04mm; S3, slurry treatment: add composite inhibitor and collector to the pretreated mineral, stir and slurry at 25 ° C, control the slurry concentration at 25wt%, stir for 10 minutes, and apply a frequency of 30kHz and a power density of 1.0W / cm 3 Ultrasonic field; Inhibitor: modified sodium lignin sulfonate (H2O2 2wt% / UV25min, molecular weight ≤ 5000Da): water glass = 1:2, dosage 800g / t; Collector: sodium oleate: sodium dodecyl sulfate: nano-TiO2 = 4:1:0.4, dosage 200g / t; S4, Shaking Table Sorting: Stage 1: The shaking table has an inclination of 4°, a stroke of 12mm, and a stroke rate of 280 times / min; it produces monazite coarse concentrate and middlings; The second stage: the middlings were pretreated with microwave radiation at 700W for 50s, with a shaking table tilt of 2°, a stroke of 8mm, and a frequency of 250 times / min to obtain garnet concentrate; S5. Tailings treatment: The tailings water is treated in a sedimentation tank and modified starch flocculant is added at a dosage of 5g / m 3 After precipitation, the supernatant is returned to the S3 slurry mixing process.

[0023] Example 2 Raw material preparation: Select the same seaside sand raw material as in Example 1.

[0024] Sorting steps: S1. Gradual desludging: Use hydrocyclone for graded desludging, control overflow particle size ≤ 0.020mm, and underflow concentration 38wt%; S2, weak magnetic separation: set the magnetic field strength to 0.3T, and perform high-frequency vibrating screen treatment after magnetic separation, with a vibration frequency of 400Hz to screen out ultrafine particles below 0.04mm; S3, slurry treatment: add composite inhibitor and collector to the pretreated mineral, stir and slurry at 30℃, control the slurry concentration at 30wt%, stir for 15 minutes, and apply a frequency of 50kHz and a power density of 1.5W / cm 3 Ultrasonic field; Inhibitor: modified sodium lignin sulfonate (H2O2 2-4wt% / UV25-35min, molecular weight ≤ 5000Da): water glass = 1:3, dosage 1200g / t; Collector: sodium oleate: sodium dodecyl sulfate: nano-TiO2 = 6:1:0.6, dosage 400g / t; S4, Shaking Table Sorting: Stage 1: The shaking table has an inclination of 6°, a stroke of 15 mm, and a stroke rate of 320 times / min; it produces monazite coarse concentrate and middlings; The second stage: the middlings were pretreated with microwave radiation at 900W for 70s, with a shaking table tilt angle of 4°, a stroke of 10mm, and a frequency of 280 times / min to obtain garnet concentrate; S5. Tailings treatment: The tailings water is treated in a sedimentation tank and modified starch flocculant is added at a dosage of 10g / m 3 After precipitation, the supernatant is returned to the S3 slurry mixing process.

[0025] Example 3 Raw material preparation: Select the same seaside sand raw material as in Example 1.

[0026] Sorting steps: S1. Gradual desludging: Use hydrocyclone for graded desludging, control overflow particle size ≤ 0.020mm, and underflow concentration 38wt%; S2, weak magnetic separation: set the magnetic field strength to 0.2T, and perform high-frequency vibrating screen treatment after magnetic separation, with a vibration frequency of 300Hz to screen out ultrafine particles below 0.04mm; S3, slurry treatment: add composite inhibitor and collector to the pretreated mineral, stir and slurry at 28 ° C, the slurry concentration is controlled at 28wt%, the stirring time is 12 minutes, and the frequency is 40kHz and the power density is 1.2W / cm 3 Ultrasonic field; Inhibitor: modified sodium lignin sulfonate (H2O2 3wt% / UV30min, molecular weight ≤5000Da): water glass = 1:2.5, dosage 1000g / t; Collector: sodium oleate: sodium dodecyl sulfate: nano-TiO2 = 5:1:0.5, dosage 300g / t; S4, Shaking Table Sorting: Stage 1: The shaking table has an inclination of 5°, a stroke of 13mm, and a stroke rate of 300 times / min; it produces monazite coarse concentrate and middlings; The second stage: the middlings were pretreated with microwave radiation at 800W for 60s, with a shaking table inclination of 3°, a stroke of 9mm, and a frequency of 260 times / min to obtain garnet concentrate; S5. Tailings treatment: The tailings water is treated in a sedimentation tank and modified starch flocculant is added at a dosage of 8g / m 3 After precipitation, the supernatant is returned to the S3 slurry mixing process.

[0027] Comparative Example 1 The difference between this comparative example and Example 3 is that no ultrasonic field is applied in step S3, and the other parameters are consistent with those in Example 3.

[0028] Comparative Example 2 The difference between this comparative example and Example 3 is that in step S4, the second-stage shaking table does not perform microwave radiation pretreatment on the middling ore before reselection, and the other parameters are the same as those in Example 3.

[0029] Comparative Example 3 The difference between this comparative example and Example 3 is that in step S3, only water glass is used as an inhibitor (added amount 1000 g / t ore sand), and the other parameters are the same as those in Example 3.

[0030] Comparative Example 4 The difference between this comparative example and Example 3 is that the collector in step S3 is sodium oleate and sodium dodecyl sulfate in a mass ratio of 5:1, and the other parameters are consistent with Example 3.

[0031] Test results: According to the seaside sand fine monazite and garnet separation process of Examples 1-3 and Comparative Examples 1-4, the recovery rate, grade of the obtained monazite and the recovery rate of garnet are as follows:

[0032] Conclusion: In Examples 1-3, through a comprehensive process of graded desludging, weak magnetic separation, ultrasonic-assisted slurry mixing, two-stage shaking table sorting, and tailings water recycling, monazite recovery rates stabilized at 92.3%-93.5%, with grades reaching 66.4%-67.8%; garnet recovery rates reached 84.1%-85.2%. Example 3 achieved the best performance, with a monazite recovery rate of 93.5%, a grade of 67.8%, and a garnet recovery rate of 85.2%, demonstrating the improvement in sorting efficiency achieved through optimized process parameters.

[0033] In Comparative Example 1, the recovery rate of monazite decreased by 16.4 percentage points, the grade decreased by 14.3 percentage points, and the recovery rate of garnet decreased by 29.6 percentage points. The ultrasonic field can enhance the adsorption of the collector on the mineral surface through the cavitation effect. After its absence, the utilization rate of the reagent decreased, resulting in a significant decline in the separation effect of the two minerals.

[0034] In Comparative Example 2, the garnet recovery rate decreased by 22 percentage points. Microwave radiation can break the residual film of reagents on the surface of the middling ore and improve the hydrophobicity of the garnet surface. The absence of this step reduces the separation efficiency of garnet and gangue, and at the same time, microcracks are generated inside the garnet, which promotes subsequent re-selection.

[0035] In Comparative Example 3, the monazite recovery rate decreased by 12.1 percentage points and the grade decreased by 10.3 percentage points. The compounding of modified sodium lignin sulfonate and water glass can synergistically inhibit gangue such as quartz. The inhibitory effect of single water glass is insufficient, resulting in an increase in the amount of gangue inclusions in the concentrate.

[0036] In Comparative Example 4, the recovery rate of monazite decreased by 7.3 percentage points, the grade decreased by 6.7 percentage points, and the recovery rate of garnet decreased by 19.6 percentage points, indicating that nano-TiO2 is crucial to enhancing the binding stability between the collector and the mineral. Nano-TiO2 can enhance the binding force between the collector and the mineral surface through bridging effect. After its absence, the adsorption stability of the agent decreases, and the sorting index shows a significant decline.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A process for separating fine monazite and garnet from seashore sand, characterized in that: The following steps are involved: S1. Pre-treating the seashore sand raw material with a particle size range of 0.074-0.15 mm by graded desludging; S2, using weak magnetic field magnetic separation to remove magnetic minerals; S3. Adding a composite inhibitor and a collector to the pretreated mineral, stirring and slurrying at 25-30° C., and applying an ultrasonic field; S4, using two-stage shaking table separation: the first stage shaking table has an inclination of 4-6 degrees, producing monazite coarse concentrate and middlings; the second stage shaking table has an inclination of 2-4 degrees, and the middlings are re-selected to obtain garnet concentrate; S5. Tailings water is recycled after being treated in a sedimentation tank.

2. A process for separating fine monazite and garnet from seashore sand according to claim 1, characterized in that: The graded desludging in step S1 adopts a hydrocyclone to control the overflow particle size to be ≤0.020 mm and the underflow concentration to be ≥35 wt%.

3. A process for separating fine monazite and garnet from seashore sand according to claim 1, characterized in that: The magnetic field strength of the magnetic separation in step S2 is 0.15-0.3T. After the magnetic separation, a high-frequency vibrating screen is used with a vibration frequency of 200-400 Hz to screen out ultrafine particles below 0.04 mm.

4. A process for separating fine monazite and garnet from seashore sand according to claim 1, characterized in that: The composite inhibitor in step S3 is a mixture of modified sodium lignin sulfonate and water glass in a mass ratio of 1:2-3, and the added amount is 800-1200g / t of ore sand; the collector is a compound of sodium oleate, sodium dodecyl sulfate and nano-titanium dioxide in a mass ratio of (4-6):1:(0.4-0.6), and the added amount is 200-400g / t of ore sand.

5. A process for separating fine monazite and garnet from seashore sand according to claim 4, characterized in that: The modified sodium lignin sulfonate is alkali lignin that has been oxidatively degraded and has a molecular weight of ≤5000Da. Specifically, it is activated by H2O2 / UV combined activation under the following activation conditions: H2O2 concentration of 2-4wt%, UV wavelength of 254nm, and irradiation time of 25-35min.

6. A process for separating fine monazite and garnet from seashore sand according to claim 1, characterized in that: The slurry concentration after slurry adjustment in step S3 is controlled at 25-30wt%, the stirring time is 10-15 minutes, the ultrasonic field frequency is 30-50kHz, and the power density is 1.0-1.5W / cm 3 .

7. A process for separating fine monazite and garnet from seashore sand according to claim 1, characterized in that: In step S4 , the stroke of the first section of the shaking table is 12-15 mm, and the stroke rate is 280-320 times / min; the stroke of the second section of the shaking table is 8-10 mm, and the stroke rate is 250-280 times / min.

8. A process for separating fine monazite and garnet from seashore sand according to claim 1, characterized in that: The ore in the second stage of the shaking table in step S4 is subjected to microwave radiation pretreatment before reselection, with a processing power of 700-900W and an irradiation time of 50-70s.

9. A process for separating fine monazite and garnet from seashore sand according to claim 1, characterized in that: In step S5, tailings water treatment uses a polymer flocculant with an addition amount of 5-10 g / m 3 After precipitation, the supernatant is recycled to the slurry preparation process in step S3. The polymer flocculant is a modified starch flocculant, which is prepared by grafting acrylamide / dimethyldiallyl ammonium chloride copolymerization of cassava starch, with a molecular weight of ≥8×10 6 Da.

10. A process for separating fine monazite and garnet from seashore sand according to claim 1, characterized in that: The concentration of the ore pulp after slurry adjustment in step S3 is controlled at 25-30wt%, and the stirring time is 10-15 minutes.

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