Method for separating collophanite by multi-size product spiral chute gravity separation

Abstract

The application provides a method for heavy floatation and combined separation of collophanite by a multi-grain product spiral chute, wherein the collophanite is first ground and slurried, then subjected to gravity separation and grading, and the product is divided into coarse-grain product, medium-grain product and fine-grain product; the medium-grain product is returned to continue grinding, and the coarse-grain product and the fine-grain product are respectively subjected to reverse flotation treatment. The application adds a medium-grain product to the common double-product gravity separation process, and the product is mostly un-dissociated dolomite. Since the physical difference in specific gravity between the apatite and the dolomite in the collophanite is small, the coarse-grain dolomite has a great influence on the grade of the coarse-grain product of the gravity separation, so the application returns the medium-grain product to the ball mill for secondary dissociation, so that the mineral processing process is simple, the operation cost is low, the separation effect is improved, the product index of the phosphate concentrate is optimized, and the rational utilization of the phosphate rock resources is realized.

Description

Technical Field

[0001] This invention belongs to the field of phosphate rock beneficiation technology, specifically relating to a method for the combined gravity flotation and beneficiation of multi-size phosphate rock using a spiral sluice. Background Technology

[0002] Phosphorus is an essential element for life, but most existing phosphate rock is sedimentary low- to medium-grade phosphorite, which cannot be directly and effectively utilized and requires appropriate separation methods. Currently, there are many methods for processing phosphate rock, with flotation being the most effective and widely used mineral processing technology. Reverse flotation is particularly used to separate phosphate rock from dolomite. However, flotation alone cannot meet the needs of all types of phosphate rock, especially given the problem of coarse and fine particle inclusions after grinding. When entering the flotation process, low-grade fine particles, due to their physical properties, often adsorb large amounts of flotation reagents during the process, and also adhere to the surface of other mineral particles. This results in difficulty in breaking the flotation foam, low flotation efficiency, and high reagent consumption. Furthermore, fine apatite particles are easily carried into the tailings, resulting in higher tailings grade and lower yield and recovery rates, causing significant waste of phosphate resources. To address this issue, a combination of gravity separation and flotation is currently employed. Gravity separation allows most of the coarse and fine particles to aggregate separately, enabling the individual separation of high-grade coarse-grained materials and low-grade fine-grained materials. This significantly reduces the adverse effects of the two types of materials being mixed in the flotation pulp on the flotation process.

[0003] CN103240169A discloses a process for combined heavy media separation and flotation of phosphate rock, which combines heavy media separation and flotation processes. It has the advantages of energy saving and high separation efficiency. However, the heavy media separation process used is applicable to a narrow particle size range and is not as universal as spiral sluice.

[0004] CN105880032A discloses a combined gravity and flotation separation method for medium- and low-grade collophane, and also discloses a combined process consisting of spiral sluice gravity separation and flotation. The selected separation equipment results in good separation performance and fine particle size. However, data from the examples show that this method suffers from significant fluctuations in product quality.

[0005] In summary, while the existing combined gravity and flotation process can mitigate the impact of coarse and fine particle mixing on flotation to some extent, the hydraulic classification also results in a lower grade of gravity concentrate due to the similar specific gravities of high-grade apatite and low-grade dolomite, which affects subsequent flotation processes. Summary of the Invention

[0006] This invention provides a method for the combined gravity flotation and beneficiation of phosphate rock using a spiral sluice with multiple product fractions. This method adds a medium-sized product to the traditional dual-product gravity separation process and returns it to the mill for further dissociation, thereby improving the separation of apatite and dolomite and enhancing the beneficiation efficiency.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for multi-size product spiral sluice gravity flotation combined separation of collophane, wherein the collophane is ground and slurry prepared, and then gravity separation is performed to classify the product into coarse-grained product, medium-grained product and fine-grained product; wherein the medium-grained product is returned for further grinding, and the coarse-grained product and the fine-grained product are respectively subjected to reverse flotation treatment.

[0008] Furthermore, during gravity separation and classification, a spiral chute is used for hydraulic classification, wherein the interception points for coarse-grained products, medium-grained products, and fine-grained products are in the following ratios from the inside to the outside of the chute length: 3-4:1-2:5.

[0009] Furthermore, in the raw collophane ore, the P2O5 grade is 22.84%–23.45%, the MgO content is 1.85%–2.36%, and the Al2O3 content is 3.46%–3.68%.

[0010] Furthermore, the medium-sized particles are returned to the grinding process and ball-milled using a separate mill. The preferred ball-milling conditions are a milling speed of 300–330 r / min, a milling time of 12–20 min, and a ball-to-material ratio of 3–5:1.

[0011] Furthermore, during gravity separation and classification, a spiral chute is used for hydraulic classification, wherein the interception points for coarse-grained products, medium-grained products, and fine-grained products are in the following ratios from the inside to the outside of the chute length: 3-4:1-2:5.

[0012] Furthermore, in the raw collophane ore, the P2O5 grade is 22.84%–23.45%, the MgO content is 1.85%–2.36%, and the Al2O3 content is 3.46%–3.68%.

[0013] Furthermore, the specific steps of this operation method are as follows:

[0014] S1. Grind the raw ore and then add water to adjust the slurry concentration to 20-30 wt%.

[0015] S2. The slurry is fed into a spiral chute and, after hydraulic classification, is divided into coarse-grained products, medium-grained products, and fine-grained products. The medium-grained products are returned to the mill for secondary dissociation.

[0016] Water is added to the coarse-grained products obtained in S3 and S2 and stirred. Phosphoric acid is added to adjust the pH. Then, reverse flotation collector is added to carry out one roughing and one scavenging operation. The roughing concentrate is the final coarse-grained product concentrate, and the scavenging concentrate is returned to the roughing system as middlings.

[0017] The fine-grained products obtained from S4 and S2 are thickened by adding starch as a flocculant, and then phosphoric acid is added to adjust the pH. Then, a reverse flotation collector is added to carry out a roughing and cleaning process. The cleaned concentrate is used as the final concentrate of the fine-grained products. The cleaned tailings are combined with the first scavenging concentrate as the raw ore for the second scavenging. The second scavenging concentrate is returned to the roughing system.

[0018] S5. Mix the coarse-grained final concentrate and the fine-grained final concentrate from S3 and S4 to obtain the final concentrate.

[0019] Furthermore, after grinding in S1, the proportion of -0.074mm is over 70%.

[0020] Furthermore, the concentration of the slurry after adding water and stirring in S3 is 20-30 wt%, and the pH is adjusted to 4.5-4.8.

[0021] Furthermore, the dosage of the reverse flotation collector in the S3 coarse-scan operation is 1.0-1.1 kg / t and 0.4-0.5 kg / t, respectively.

[0022] Furthermore, the flocculant in S3 is industrial corn starch, with a dosage of 1.0-1.2 kg / t, a slurry concentration of 20-25 wt%, and a pH adjusted to 4.5-4.8.

[0023] Furthermore, in S3, the roughing and cleaning scavenging operations only involve adding reagents during the roughing and first scavenging stages, with reverse flotation collector dosages of 0.7–0.8 kg / t and 0.2–0.3 kg / t, respectively.

[0024] The present invention has the following beneficial effects:

[0025] During the gravity separation of phosphate ore using a sluice box, the grade exhibits a "V" shape at the sluice box outlet, meaning the phosphate ore grade decreases and then increases from the inside out of the sluice box. Further experimental verification by the inventors revealed that the lowest grade portion is primarily dolomite; dolomite is easily ground, and finely ground dolomite exhibits high liberation of individual particles, resulting in a majority of fine-grained particles. However, some coarse particles remain that are not completely liberated. Furthermore, the physical difference in specific gravity between apatite (3.1-3.2%) and dolomite (2.85-2.9%) in the phosphate ore is small. During the separation process using a spiral sluice box, the separation bands of dolomite and apatite with similar particle sizes are not obvious. Therefore, this invention adds a medium-sized product during gravity separation and returns it to the mill for further liberation. This is equivalent to removing some low-grade coarse particles, reducing the influence of incompletely liberated coarse dolomite particles in the coarse-grained product, improving the grade of the coarse-grained product before flotation, saving the consumption of flotation reagents, and achieving efficient separation of phosphate rock.

[0026] This invention addresses the issue of incompletely dissociated coarse dolomite particles being completely dissociated through regrinding, transforming them from useless tailings into part of the fine-grained product. This increases the yield and recovery rate of the final concentrate. Furthermore, the invention simplifies the process flow, reduces the types and quantities of flotation reagents, lowers production costs, and enables the effective recovery and utilization of phosphorus resources.

[0027] Using the mineral processing technology of this invention, the P2O5 grade of phosphate concentrate is ≥32%, and the phosphate concentrate recovery rate is ≥78%. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention.

[0030] Unless otherwise specified, the reagents used in the following implementations are commercially available chemical reagents or industrial products.

[0031] Example 1

[0032] A method for the combined gravity flotation and separation of multi-size phosphate rock using a spiral sluice, the process flow is as follows: Figure 1 .

[0033] 1) The sample used in this embodiment comes from a phosphate mine in Yichang. The P2O5 grade is 23.07%, the MgO content is 2.02%, the Al2O3 content is 3.56%, and the grinding fineness is -0.074mm. The percentage of mineral particles is 70%. Water is added to adjust the slurry to a concentration of 25wt%, so that the phosphate minerals are separated from the gangue. The main gangue minerals are magnesium compounds and sesquioxides.

[0034] 2) Add the prepared slurry to a spiral chute with a diameter of 1.2 meters and a radius-to-diameter ratio of 0.8. The interception points of coarse, medium, and fine particles are taken from the inside out in a ratio of 3.5:1.5:5 of the chute length, respectively. That is, coarse, medium, and fine particles are taken from the chute in the ranges of 0-210mm, 210-300mm, and 300-600mm from the inside out, respectively. The medium particles are returned for regrinding.

[0035] 3) Coarse-grained products are divided into one coarse and one sweeping operation.

[0036] Coarse-grained product flotation stage: Water is added to the obtained coarse-grained product to adjust the slurry concentration to 25%, phosphoric acid is added to adjust the pH, and then reverse flotation collector is added to carry out reverse flotation operation. The amount of phosphoric acid is 11.0 kg / t, and the amount of reverse flotation collector is 1.0 kg / t.

[0037] 4) Fine-grained products are divided into two sweeping operations: one coarse and one fine.

[0038] Fine-grained product flotation stage: Starch is added to the obtained fine-grained product as a flocculant for thickening, and its pulp concentration is controlled at 25%. Phosphoric acid is added, stirred and adjusted, and then reverse flotation collector is added to carry out one roughing and one cleaning scavenging operation. Collectors are only added in the roughing and the first scavenging. The dosage of phosphoric acid is 15.0 kg / t, and the dosage of reverse flotation collector is 0.7 kg / t and 0.2 kg / t, respectively.

[0039] Finally, the coarse-grained final concentrate and the fine-grained final concentrate are mixed to obtain the final concentrate. X1 is the tailings from the coarse-grained scavenging process, and X2 and X3 are the tailings from the fine-grained scavenging process.

[0040] Through the above experiments, the final concentrates of coarse and fine-grained products were obtained, as shown in Table 1.

[0041] Table 1 (Unit: %)

[0042]

[0043] In this embodiment, the flotation concentrate obtained by the combined gravity flotation and separation process has a P2O5 grade of 32.29%, a yield of 57.02%, and a recovery rate of 79.82%.

[0044] Example 2

[0045] A method for combined gravity flotation and separation of phosphate rock using a spiral sluice for multi-scale products. The sample properties in this embodiment are the same as in Example 1, but the medium-sized product is not returned for regrinding; it directly enters the coarse-sized product. In the spiral sluice, the ratio of the collection points for the coarse-sized product and the fine-sized product from the inside to the outside of the sluice is 5:5, while the dosage of other reagents remains unchanged.

[0046] Coarse-grained products are processed in two stages: coarse and fine.

[0047] Coarse-grained product flotation stage: Water is added to the obtained coarse-grained product to adjust the slurry concentration to 25%, phosphoric acid is added to adjust the pH, and then reverse flotation collector is added to carry out reverse flotation operation. The amount of phosphoric acid is 11.0 kg / t, and the amount of reverse flotation collector is 1.0 kg / t.

[0048] Fine-grained products are processed in two stages: one coarse and one fine.

[0049] Fine-grained product flotation stage: Starch is added to the obtained fine-grained product as a flocculant for thickening, and its pulp concentration is controlled at 25%. Phosphoric acid is added, stirred and adjusted, and then reverse flotation collector is added to carry out one roughing and one cleaning scavenging operation. Collectors are only added in the roughing and the first scavenging. The dosage of phosphoric acid is 15.0 kg / t, and the dosage of reverse flotation collector is 0.7 kg / t and 0.2 kg / t, respectively.

[0050] Finally, the coarse-grained final concentrate and the fine-grained final concentrate are mixed to obtain the final concentrate.

[0051] Through the above experiments, the final concentrates of coarse and fine-grained products were obtained, as shown in Table 2.

[0052] Table 2 (Unit: %)

[0053]

[0054] The flotation concentrate obtained by the combined gravity flotation and separation process had a P2O5 grade of 31.87%, a yield of 52.96%, and a recovery rate of 73.15%.

[0055] Example 3

[0056] A method for combined gravity flotation and separation of phosphate rock using a spiral sluice for multi-size products. The sample properties and gravity separation methods in this embodiment are the same as in Example 1, but the medium-sized product (P2O5 grade 16.84) is discarded and not regrinded; otherwise, it is the same as in Example 1.

[0057] Coarse-grained products are processed in two stages: coarse and fine.

[0058] Coarse-grained product flotation stage: Water is added to the obtained coarse-grained product to adjust the slurry concentration to 25%, phosphoric acid is added to adjust the pH, and then reverse flotation collector is added to carry out reverse flotation operation. The amount of phosphoric acid is 11.0 kg / t, and the amount of reverse flotation collector is 1.0 kg / t.

[0059] Fine-grained products are processed in two stages: one coarse and one fine.

[0060] Fine-grained product flotation stage: Starch is added to the obtained fine-grained product as a flocculant for thickening, and its pulp concentration is controlled at 25%. Phosphoric acid is added, stirred and adjusted, and then reverse flotation collector is added to carry out one roughing and one cleaning scavenging operation. Collectors are only added in the roughing and the first scavenging. The dosage of phosphoric acid is 15.0 kg / t, and the dosage of reverse flotation collector is 0.7 kg / t and 0.2 kg / t, respectively.

[0061] Finally, the coarse-grained final concentrate and the fine-grained final concentrate are mixed to obtain the final concentrate.

[0062] Through the above experiments, the final concentrates of coarse and fine-grained products were obtained, as shown in Table 3.

[0063] Table 3 (Unit: %)

[0064]

[0065] The flotation concentrate obtained by the combined gravity flotation and separation process had a P2O5 grade of 33.25%, a yield of 47.89%, and a recovery rate of 66.14%.

[0066] Example 4

[0067] A method for combined gravity flotation and separation of phosphate rock using a spiral sluice for multi-size products. The sample properties in this embodiment are the same as in Example 1, except that the ratio of the interception points for coarse, medium, and fine-size products to the length of the sluice is changed from the inside to the outside to 4:2:4. The rest of the process remains unchanged, and the amount of reagents added is the same as in Example 1.

[0068] Coarse-grained products are processed in two stages: coarse and fine.

[0069] Coarse-grained product flotation stage: Water is added to the obtained coarse-grained product to adjust the slurry concentration to 25%, phosphoric acid is added to adjust the pH, and then reverse flotation collector is added to carry out reverse flotation operation. The amount of phosphoric acid is 11.0 kg / t, and the amount of reverse flotation collector is 1.0 kg / t.

[0070] Fine-grained products are processed in two stages: one coarse and one fine.

[0071] Fine-grained product flotation stage: Starch is added to the obtained fine-grained product as a flocculant for thickening, and its pulp concentration is controlled at 25%. Phosphoric acid is added, stirred and adjusted, and then reverse flotation collector is added to carry out one roughing and one cleaning scavenging operation. Collectors are only added in the roughing and the first scavenging. The dosage of phosphoric acid is 15.0 kg / t, and the dosage of reverse flotation collector is 0.7 kg / t and 0.2 kg / t, respectively.

[0072] Finally, the coarse-grained final concentrate and the fine-grained final concentrate are mixed to obtain the final concentrate.

[0073] Through the above experiments, the final concentrates of coarse and fine-grained products were obtained, as shown in Table 4.

[0074] Table 4 (Unit: %)

[0075]

[0076] The flotation concentrate obtained by the combined gravity flotation and separation process had a P2O5 grade of 31.14%, a yield of 51.37%, and a recovery rate of 69.34%.

[0077] Comparing Example 1 and Example 2, regrinding the medium-particle-size product and directly mixing it with the coarse-particle-size product, while keeping the reagent dosage constant, resulted in a 0.5 percentage point increase in the final concentrate P2O5 grade, but a 5 percentage point increase in both yield and recovery. Comparing Example 1 and Example 3, discarding the low-grade medium-particle-size product directly resulted in a higher P2O5 grade but a significantly reduced recovery rate, leading to a substantial waste of effective minerals. Comparing Example 1 and Example 4, adjusting the selection range of the medium-particle-size product during regrinding resulted in significant differences in P2O5 grade, yield, and recovery.

[0078] Example 5

[0079] Based on Example 1, the only difference is that the medium-sized product is ground separately using a mill with a ball mill speed of 300 r / min, a ball milling time of 15 min, and a ball-to-material ratio of 4:1.

[0080] The flotation concentrate obtained by the combined gravity flotation and separation process had a P2O5 grade of 32.54%, a yield of 60.27%, and a recovery rate of 82.62%.

[0081] Example 6

[0082] Based on Example 1, the only difference is that in the spiral chute, the ratio of the interception points of coarse-grained product, medium-grained product and fine-grained product to the length of the chute from the inside to the outside is 3:2:5.

[0083] The flotation concentrate obtained by the combined gravity flotation and separation process had a P2O5 grade of 32.02%, a yield of 55.27%, and a recovery rate of 78.32%.

[0084] Example 7

[0085] Based on Example 1, the only difference is that in the spiral chute, the ratio of the interception points of coarse-grained product, medium-grained product and fine-grained product to the length of the chute from the inside to the outside is 5:2:3.

[0086] The flotation concentrate obtained by the combined gravity flotation and separation process had a P2O5 grade of 29.14%, a yield of 64.12%, and a recovery rate of 75.15%.

[0087] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for combined gravity flotation and separation of multi-stage phosphate rock using a spiral sluice, characterized in that... The collophane ore was ground and slurry-conditioned, followed by gravity separation to classify the product into coarse, medium, and fine particles. The medium particles were returned for further grinding, while the coarse and fine particles were subjected to reverse flotation. Hydraulic classification was performed using a spiral sluice, with the interception points for coarse, medium, and fine particles in a ratio of 3-4:1-2:5 from the inside to the outside of the sluice. The specific steps of this method are as follows: S1. Grind the raw ore and then add water to adjust the slurry concentration to 20-30 wt%. S2. The slurry is fed into a spiral chute and, after hydraulic classification, is divided into coarse-grained products, medium-grained products, and fine-grained products. The medium-grained products are returned to the mill for secondary dissociation. Water is added to the coarse-grained products obtained in S3 and S2 and stirred. Phosphoric acid is added to adjust the pH. Then, reverse flotation collector is added to carry out one roughing and one scavenging operation. The roughing concentrate is the final coarse-grained product concentrate, and the scavenging concentrate is returned to the roughing system as middlings. The fine-grained products obtained from S4 and S2 are thickened by adding starch as a flocculant, and then phosphoric acid is added to adjust the pH. Then, a reverse flotation collector is added to carry out a roughing and cleaning two-stage scavenging operation. The cleaned concentrate is used as the final concentrate of the fine-grained products. The cleaned tailings are combined with the first scavenging concentrate as the raw ore for the second scavenging. The second scavenging concentrate is returned to the roughing system. S5. Mix the coarse-grained final concentrate and the fine-grained final concentrate from S3 and S4 to obtain the final concentrate.

2. The method according to claim 1, characterized in that: In the raw collophane ore, the P2O5 grade is 22.84%~23.45%, the MgO content is 1.85%-2.36%, and the Al2O3 content is 3.46%-3.68%.

3. The method according to claim 1, characterized in that: Medium-sized particles are returned to the grinding process and ball-milled using a separate mill; the ball mill speed is 300-330 r / min, the ball milling time is 12-20 min, and the ball-to-material ratio is 3-5:

1.

4. The method according to claim 1, characterized in that: After grinding in S1, the proportion of -0.074mm is over 70%.

5. The method according to claim 1, characterized in that: The slurry concentration after adding water and stirring in S3 is 20-30 wt%, and the pH is adjusted to 4.5-4.

8.

6. The method according to claim 1, characterized in that: In S3, the dosage of the reverse flotation collector for the first roughing and scavenging operation is 1.0-1.1 kg / t and 0.4-0.5 kg / t, respectively.

7. The method according to claim 1, characterized in that: In S3, the flocculant is industrial corn starch, with a dosage of 1.0~1.2 kg / t, a slurry concentration of 20-25 wt%, and a pH adjusted to 4.5~4.

8.

8. The method according to claim 7, characterized in that: In S3, the roughing and cleaning scavenging operations only involve adding reagents during the roughing and first scavenging stages, with reverse flotation collector dosages of 0.7~0.8 kg / t and 0.2~0.3 kg / t, respectively.

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