A method for coarse flotation of carbonatic-type phosphorite

Abstract

The application discloses a carbonate-type phosphate rock coarse particle flotation method and relates to the technical field of phosphate rock flotation. The -500mm ore is crushed to -1mm; an adjusting agent is added to adjust the slurry, and then a coarse particle level collector is added to adjust the slurry, and then air flotation is carried out for 3-5 minutes to obtain roughing phosphate concentrate and tailings, and the tailings are directly discarded; the roughing phosphate concentrate is concentrated and ground to -0.425mm to perform reselection operation, an adjusting agent and a coarse particle level collector are added to perform flotation for 1-3 minutes, and cleaning phosphate concentrate and tailings are obtained, the tailings are discarded after scavenging operation or directly discarded; the cleaning phosphate concentrate is subjected to 0.23mm classification treatment, the particle size larger than 0.23mm is returned to the flotation after being ground with the roughing phosphate concentrate, and the particle size smaller than 0.23mm is used as final phosphate concentrate. Through the above method, the technological process of ore coarse particle flotation-coarse particle grinding-coarse particle classification is realized, the over-grinding phenomenon caused by directly grinding the crushed ore is avoided, and the production process is simple and the production cost is low.

Description

Technical Field

[0001] This invention relates to the field of phosphate rock flotation technology, specifically to a coarse-grained flotation method for carbonate-type phosphate rock. Background Technology

[0002] Before flotation, phosphate rock typically requires grinding to a certain fineness, usually controlled by the passing through a 0.074mm standard sieve. After grinding, reagents are added to the pulp for conditioning and aeration flotation. However, random, non-selective grinding can easily lead to over-grinding of some ore. While fine grinding improves monomer liberation, fine minerals tend to adhere to the surface of coarse particles or agglomerate, resulting in poor flotation selectivity, difficulty in removing impurities, low concentrate quality, high tailings content, high reagent consumption, and sticky froth. CN103386365A discloses a dual-stage positive and negative flotation method for siliceous calcium phosphate rock. One stage of positive flotation is used for pulp with a grinding fineness of -0.074mm and a content of 92-99%, while the second stage is used for pulp with a grinding fineness of -0.020mm and a content of 70-90%. Both flotation processes have strict requirements for grinding fineness. However, for carbonate-type phosphate rock, the carbonate minerals are mainly dolomite and calcite, while other gangue minerals such as quartz, iron, and aluminum are relatively low. This type of phosphate rock has a P2O5 content of 21-25% and an MgO content of 4-6%, similar to that of typical collophane. It has a high CaO content, with a CaO / P2O5 ratio as high as 1.8%; a low SiO2 content, around 2%; and low Fe2O3 and Al2O3 contents, around 0.5% each. This type of ore readily reacts with inorganic acids to generate a large number of bubbles, leading to an increased reverse flotation rate, sticky froth, severe mechanical entrainment of the froth, deteriorated flotation performance, high reagent consumption, and difficulty in process control. Summary of the Invention

[0003] The purpose of this invention is to provide a coarse-grained flotation method for carbonated phosphate rock, which solves the problems of high cost, poor separation, and difficulty in controlling the flotation process and unsatisfactory flotation indicators in existing fine grinding methods.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a coarse-grained flotation method for carbonate-type phosphate rock, characterized by comprising the following steps:

[0005] S1. In a closed-loop crushing and screening system, crush -500mm ore to -1mm and mix thoroughly for later use;

[0006] S2. After step S1, the -1mm ore is treated with a modifier to adjust the slurry, and then coarse-grained collector is added to adjust the slurry. After aeration and flotation for 3-5 minutes, a rougher phosphate concentrate with P2O5 content ≥27.6%, MgO content ≤2%, and MER ≤0.11 and tailings 1 are obtained. Tailings 1 are directly discarded.

[0007] S3. The crude phosphate concentrate obtained in step S2 is concentrated and ground to -0.425mm for re-selection. A modifier and coarse collector are added and floated for 1-3 minutes to obtain a selected phosphate concentrate with P2O5 content ≥29%, MgO content ≤0.8%, and MER ≤0.06 and tailings 2. Tailings 2 are scavenged and discarded or directly discarded.

[0008] S4. The selected phosphate concentrate obtained in step S3 is subjected to 0.23mm classification. The particles larger than 0.23mm are returned to step S3 and ground with the rough phosphate concentrate for flotation. The particles smaller than 0.23mm are used as the final phosphate concentrate. The final phosphate concentrate has a P2O5 content ≥30%, an MgO content ≤0.8%, and a MER of 0.05.

[0009] When the required MgO content in the flotation concentrate is less than 1.5%, it can be obtained directly by flotation without grinding the ore according to step S1; when the required P2O5 content is ≥29% and the MgO content is less than 0.8% in the concentrate, the crude phosphate concentrate is subjected to coarse grinding and reflotation according to step S3; when the required P2O5 content is ≥30% and the MgO content is less than 0.8% in the concentrate, the refined phosphate concentrate is classified according to step S4, and the +0.23mm particle size is returned for regrinding and reflotation.

[0010] A further technical solution is that the modifier is one of phosphoric acid, sulfur-phosphoric acid mixture, or a phosphorus-containing modifier. When using phosphoric acid, the concentration is 30%–60%, and the dosage is 6–8 kg / t. The sulfur-phosphoric acid mixture is prepared by first diluting 95% concentrated sulfuric acid with water to a 40%–50% concentration, then adding 24% phosphoric acid and mixing. The ratio of sulfuric acid to phosphoric acid is 15–3:1, and the dosage is 8–14 kg / t. The phosphorus-containing modifier is one or more of polyphosphoric acid, sodium tripolyphosphate, trisodium phosphate, and sodium phosphate, used in combination, at a dosage of 200–800 g / t.

[0011] A further technical solution is that the coarse-grained collector is composed of a mixture of sodium salts of fatty acids, straight-chain sulfonates, and alcohols in a ratio of 5:3:2.

[0012] A further technical solution is that the linear sulfonate is at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfonate, sodium tetradecyl sulfonate, and sodium hexadecyl sulfonate; and the alcohol is at least one of pine oil, isoamyl alcohol, isooctanol, and diisobutylmethanol.

[0013] A further technical solution is that in the carbonate-type phosphate rock, phosphate minerals account for 50% to 70% of the total mineral content, carbonate minerals account for 20% to 30%, and the remainder consists of siliceous and silicate minerals, limonite, and mica. Among the carbonate minerals, calcite accounts for 30% to 50% and dolomite accounts for 50% to 70%.

[0014] A further technical solution is that in step S2, the conditioning time of the modifier is 10-30 seconds, the conditioning time of the collector is 30-60 seconds, and the concentration of the slurry after conditioning is 28% ± 1%.

[0015] A further technical solution is that in step S3, the concentration of the crude phosphate concentrate after concentration is 65% to 75%, the conditioning time of the modifier is 10 to 30 seconds, the conditioning time of the collector is 60 to 120 seconds, and the concentration of the slurry after conditioning is 28% ± 3%.

[0016] Reaction Mechanism: This type of ore has a high content of carbonate minerals and good floatability. The linear sulfonate surfactant used in this collector readily competes with calcite and dolomite for preferential adsorption in the phosphate rock pulp, rather than with phosphate minerals. Therefore, the pulp mixing time is short, and the flotation time is short (high flotation rate), resulting in low P2O5 content in the tailings. However, when the phosphate rock is ground to 200 mesh, the specific surface area of ​​phosphate minerals, calcite, and dolomite increases significantly. The collector easily undergoes non-selective adsorption on the mineral surface, leading to poor flotation selectivity. The concentrate has low P2O5 content, while the tailings have high P2O5 content, and the flotation froth tends to become sticky, making operation and control difficult. Therefore, coarse-grained flotation is recommended for this type of ore.

[0017] Compared with the prior art, the beneficial effects of the present invention are: to provide a coarse flotation method for carbonate-type phosphate rock, realizing the process flow of coarse flotation, coarse grinding and coarse classification of ore, avoiding the over-grinding phenomenon caused by direct grinding after crushing of the ore, and the production process is simple and the production cost is low. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] Example 1

[0021] For carbonate-type phosphate blocks, the carbonate minerals are calcite and dolomite, with a calcite-to-dolomite ratio of 3:2. The P2O5 content is 25.31%, MgO content is 3.11%, and SiO2 content is 2.8%. After crushing and sieving to a particle size of -1 mm, 6 kg / t of phosphoric acid (30% phosphoric acid concentration) is added to water, and the slurry is prepared for 0.5 minutes, controlling the pH to 5 (the concentration after preparation is 27%). Then, 1.5 kg / t of coarse-grained collector is added (the coarse-grained collector is composed of a mixture of sodium salts of fatty acids, linear sulfonates, and alcohols in a 5:3:2 ratio; the linear sulfonate is sodium dodecylbenzene sulfonate, and the alcohol is pine oil), the slurry is prepared for 2 minutes, and the concentration after preparation is 25%. Aeration flotation is performed for 3 minutes at a gas flow rate of 1.0 m³ / t. 3 The yield of rough phosphate concentrate was 86.74% per hour, with a P2O5 content of 28.37%, an MgO content of 1.24%, and a MER ≤ 0.11. The recovery rate of rough phosphate concentrate was 98.06%. The yield of tailings was 13.36%, with a P2O5 content of 3.67%.

[0022] The roughed phosphate concentrate slurry was naturally settled and concentrated to 60%. It was then ground using a rod mill for 1 minute to achieve a particle size of -0.425 mm. The slurry was adjusted to a concentration of 30%, and 3 kg / t of phosphoric acid (35% phosphoric acid concentration, 28% after adjustment) was added for 45 seconds, controlling the pH at 4.8. Next, 0.5 kg / t of a coarse-grained collector was added, and the slurry was adjusted for 2 minutes. The coarse-grained collector consisted of a mixture of sodium fatty acid salts, linear sulfonates, and alcohols in a 5:3:2 ratio. The linear sulfonate was sodium dodecyl sulfonate, and the alcohol was isoamyl alcohol. The final concentration after adjustment was 28%. Aeration flotation was performed for 2.5 minutes at a gas flow rate of 1.0 m³ / s. 3 / h, the yield of refined phosphate concentrate is 80.09%, of which P2O5 content is 29.59% and MgO content is 0.75%. The recovery rate of rough phosphate concentrate is 93.61% and MER≤0.06. The P2O5 content in tailings 2 is 9%. Tailings 2 can be selected for scavenging and disposal or directly disposed of as tailings.

[0023] The selected phosphate concentrate was classified into 0.23mm particles using a vibrating screen. The +0.23mm particle size ore (with a particle size percentage of 2.6%) was combined with the rough phosphate concentrate and ground before further beneficiation. The -0.23mm particle size ore was directly used as the final high-quality phosphate concentrate, with a P2O5 content of 30.33%, an MgO content of 0.65%, and a MER value of 0.05.

[0024] Example 2

[0025] For carbonate-type phosphate blocks, the carbonate minerals are calcite and dolomite in a 1:1 ratio, with a P2O5 content of 23.52%, MgO content of 4.3%, and SiO2 content of 3.23%. After crushing and sieving to a particle size of -1 mm, water is added directly to form a slurry. 6 kg / t of phosphoric acid is added, with a slurry preparation time of 1 minute, controlling the pH to 5 (phosphoric acid concentration is 35%, and the concentration after slurry preparation is 28%). Then, 1.5 kg / t of coarse-grained collector is added (the coarse-grained collector is composed of a mixture of sodium fatty acid salts, linear sulfonates, and alcohols in a 5:3:2 ratio; the linear sulfonate is sodium tetradecyl sulfonate, and the alcohol is isooctanol), with a slurry preparation time of 2.5 minutes (the concentration after slurry preparation is 28%). Aeration flotation is then performed for 3.5 minutes at a gas flow rate of 1.5 m³ / s. 3 The yield of rough phosphate concentrate was 76.42% per hour, with a P2O5 content of 27.89% and an MgO content of 1.7%, and the recovery rate of rough phosphate concentrate was 96.55%. The tailings yield was 23.58%, with a P2O5 content of 3.23%.

[0026] The roughed phosphate concentrate slurry was naturally settled and concentrated to 60%. It was then ground using a rod mill for 1 minute to achieve a particle size of -0.425 mm. The slurry was adjusted to a concentration of 30%, and 3 kg / t of phosphoric acid (40% concentration) was added for 1 minute, resulting in a pH of 5 and a final concentration of 29%. Next, 0.5 kg / t of coarse-grained collector (composed of a mixture of sodium fatty acid salts, straight-chain sulfonates, and alcohols in a 5:3:2 ratio; the straight-chain sulfonate was sodium hexadecyl sulfonate, and the alcohol was diisobutylmethanol) was added. The slurry was adjusted for 3 minutes, resulting in a final concentration of 30%. Aeration flotation was then performed for 3 minutes at a gas flow rate of 1.5 m³ / t. 3 The yield of refined phosphate concentrate is 80.09% per hour, with a P2O5 content of 29.06% and an MgO content of 0.86%. The recovery rate of rough phosphate concentrate is 91.82%. The P2O5 content in tailings 2 is 12%. Tailings 2 can be selected for scavenging and then discarded.

[0027] The selected phosphate concentrate was classified into 0.23mm particles using a vibrating screen. The +0.23mm particle size ore (with a particle size percentage of 4.3%) was combined with the rough phosphate concentrate and ground before further beneficiation. The -0.23mm particle size ore was directly used as the final high-quality phosphate concentrate, with a P2O5 content of 30.22%, an MgO content of 0.71%, and a MER value of 0.06.

[0028] Example 3

[0029] For carbonate-type phosphate blocks, the carbonate minerals are calcite and dolomite, with a ratio of 2:3. The P2O5 content is 21.90%, the MgO content is 5.30%, and the SiO2 content is 2.5%. The blocks are crushed and sieved to a particle size of -1mm, and then water is added directly to form a slurry. Add 6 kg / t of phosphoric acid, adjust the slurry for 1 minute, and set the pH to 5 (phosphoric acid concentration is 40%, and the concentration after adjustment is 28%). Then add 1.5 kg / t of coarse-grained collector (the coarse-grained collector is composed of a mixture of sodium salt of fatty acids, linear sulfonate, and alcohol in a ratio of 5:3:2; the linear sulfonate is sodium hexadecyl sulfonate, and the alcohol is diisobutylmethanol), adjust the slurry for 3 minutes, adjust to 31%, and perform aeration flotation for 3.5 minutes. The rougher phosphate concentrate yield is 77.9%, with a P2O5 content of 27.64% and an MgO content of 1.94%, and the rougher phosphate concentrate recovery rate is 96.59%. The tailings yield is 22.10%, with a P2O5 content of 3.43%.

[0030] The roughed phosphate concentrate slurry was naturally settled and concentrated to 65%. It was then ground using a rod mill for 1 minute to achieve a particle size of -0.425 mm. The slurry was adjusted to a concentration of 30%, and 3 kg / t of phosphoric acid was added for 0.5 minutes, resulting in a pH of 5 (the phosphoric acid concentration was 40%, and the adjusted concentration was 28%). Next, 0.5 kg / t of coarse-grained collector was added (the coarse-grained collector consisted of a mixture of sodium fatty acid salts, linear sulfonates, and alcohols in a 5:3:2 ratio; the linear sulfonate was sodium dodecylbenzene sulfonate, and the alcohol was pine oil). The slurry was adjusted for 2–3 minutes (the adjusted concentration was 28% ± 3%), followed by 2 minutes of aeration flotation (the gas flow rate during aeration flotation was 2 m³ / s). 3 The yield of refined phosphate concentrate was 80.09%, with a P2O5 content of 29.06% and an MgO content of 0.86%. The recovery rate of rough phosphate concentrate was 91.82%. The P2O5 content in tailings 2 was 13%. Tailings 2 can be selected for scavenging and then discarded.

[0031] The selected phosphate concentrate was classified into 0.23mm particles using a vibrating screen. The +0.23mm particle size ore (particle size percentage of 5.91%) was combined with the rough phosphate concentrate and ground before further selection. The -0.23mm particle size ore was directly used as the final high-quality phosphate concentrate, with a P2O5 content of 30.53% and an MgO content of 0.65%.

[0032] Although the invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope of this disclosure. More specifically, various modifications and improvements can be made to the components or layouts within the scope of this disclosure, the drawings, and the claims. Besides modifications and improvements to the components or layouts, other uses will be apparent to those skilled in the art.

Claims

1. A method for coarse-grained flotation of carbonate-type phosphate rock, characterized in that: The carbonate-type phosphate rock contains 50%–70% phosphate minerals and 20%–30% carbonate minerals, with the remainder being siliceous and silicate minerals, limonite, and mica. Among the carbonate minerals, calcite accounts for 30%–50% and dolomite for 50%–70%. The method includes the following steps: Step S1. Crush the -500mm ore to -1mm in a closed-circuit crushing and screening system and mix them evenly for later use; Step S2. After step S1, the -1mm ore is treated with a modifier to adjust the slurry, and then coarse-grained collector is added to adjust the slurry. After aeration and flotation for 3-5 minutes, a rougher phosphate concentrate with P2O5 content ≥27.6%, MgO content ≤2%, and MER ≤0.11 and tailings 1 are obtained. Tailings 1 are directly discarded. Step S3. The rough phosphate concentrate obtained in step S2 is concentrated and ground to -0.425mm for further refining. A modifier and a coarse-grained collector are added, and the mixture is floated for 1-3 minutes to obtain refined phosphate concentrate with P2O5 content ≥29%, MgO content ≤0.8%, and MER ≤0.06, and tailings 2. Tailings 2 are then scavenged and discarded or directly discarded. The coarse-grained collector is composed of a mixture of sodium salts of fatty acids, straight-chain sulfonates, and alcohols in a ratio of 5:3:

2. Step S4. The selected phosphate concentrate obtained in step S3 is subjected to 0.23mm classification. The particles larger than 0.23mm are returned to step S3 and ground with the rough phosphate concentrate for flotation. The particles smaller than 0.23mm are used as the final phosphate concentrate. The final phosphate concentrate has a P2O5 content ≥30%, an MgO content ≤0.8%, and a MER of 0.

05. When the required MgO content in the flotation concentrate is less than 1.5%, it can be obtained directly by flotation without grinding the ore according to step S1; when the required P2O5 content is ≥29% and the MgO content is less than 0.8% in the concentrate, the rough phosphate concentrate is subjected to coarse grinding and reflotation according to step S3; when the required P2O5 content is ≥30% and the MgO content is less than 0.8% in the concentrate, the refined phosphate concentrate is classified according to step S4, and the +0.23mm particle size is returned for regrinding and reflotation.

2. The coarse-grained flotation method for carbonate-type phosphate rock according to claim 1, characterized in that: The modifier is one of phosphoric acid, sulfur-phosphoric acid mixture, or phosphorus-containing modifier; when using phosphoric acid, the phosphoric acid concentration is 30%–60%, and the dosage is 6–8 kg / t; the sulfur-phosphoric acid mixture is prepared by first diluting 95% concentrated sulfuric acid with water to make 40%–50% dilute sulfuric acid, and then adding 24% phosphoric acid for mixing, wherein the ratio of sulfuric acid to phosphoric acid is 15–3:1, and the dosage is 8–14 kg / t; the phosphorus-containing modifier is one or more of polyphosphoric acid, sodium tripolyphosphate, trisodium phosphate, and sodium phosphate, and the dosage is 200–800 g / t.

3. The coarse-grained flotation method for carbonate-type phosphate rock according to claim 1, characterized in that: The linear sulfonate is at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfonate, sodium tetradecyl sulfonate, and sodium hexadecyl sulfonate; the alcohol is at least one of pine oil, isoamyl alcohol, isooctanol, and diisobutylmethanol.

4. The coarse-grained flotation method for carbonate-type phosphate rock according to claim 1, characterized in that: In step S2, the conditioning time for the modifier is 0.5 to 1 minute, and the conditioning time for the collector is 2 to 3 minutes. After conditioning, the slurry concentration is 28% ± 1%.

5. The coarse-grained flotation method for carbonate-type phosphate rock according to claim 1, characterized in that: In step S3, the concentration of the concentrated phosphate concentrate after roughing is 65% to 75%, the conditioning time of the modifier is 0.5 to 1 minute, the conditioning time of the collector is 2 to 3 minutes, and the concentration of the slurry after conditioning is 28% ± 3%.

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