Stage grinding-magnetic levitation combined efficient beneficiation process for micro-fine particle lean magnetic iron ore

Abstract

The invention discloses a stage grinding-magnetic levitation combined efficient beneficiation process for micro-fine particle lean magnetite, and relates to the technical field of beneficiation of low-grade magnetite. The stage grinding-magnetic levitation combined efficient beneficiation process for the micro-fine particle lean magnetic iron ore specifically comprises the following steps that S1, ore feeding operation is conducted; s2, ore grinding operation is conducted, then ore is graded, ore grinding operation is conducted on large particles again, and S3 is conducted on small particles; and S3, low-intensity magnetic separation 1 operation is carried out. According to the stage grinding-magnetic levitation combined efficient beneficiation process for the micro-fine particle lean magnetic iron ore, flotation concentrates obtained through two times of flotation are combined into final total concentrates. The method has the advantages of being high in iron ore concentrate grade, high in magnetic iron recovery rate, small in flotation feeding amount, stable in index, high in applicability and the like.

Description

Technical Field

[0001] This invention relates to the field of low-grade magnetite ore beneficiation technology, specifically to a high-efficiency beneficiation process combining stage grinding and magnetic levitation for fine-grained lean magnetite ore. Background Technology

[0002] my country is a major steel producer and has the world's largest demand for iron ore, but the domestic supply of iron ore and iron concentrate is far from sufficient. With rapid socio-economic development, my country's demand for iron ore resources will continue to rise.

[0003] my country's iron ore resources are relatively poor, with a predominance of low-grade ores and a scarcity of high-grade ones. The ores also contain many associated components and have fine-grained minerals. Most iron ores require beneficiation screening before smelting. Given the current supply-side reforms and environmental production restrictions in the steel industry, there is an urgent need to develop efficient, energy-saving, and low-cost beneficiation processes for low-grade, fine-grained iron ore. Improving the utilization rate of iron ore resources is crucial for the sustainable development of my country's mineral resources and the steel industry.

[0004] Extensive research and production practice have shown that to obtain high-quality iron concentrate from fine-grained, difficult-to-process iron ore beneficiation plants, a single magnetic separation process is insufficient; a combined magnetic separation-flotation beneficiation process is often required. However, in production practice, weak magnetic separators are effective for separating fine-grained, strongly magnetic minerals, but they are ineffective for separating valuable minerals with significant differences in particle size distribution and ore properties.

[0005] To address the challenges in beneficiation technology for fine-grained magnetite ore, Chinese patent ZL201310560636.7 discloses an energy-saving iron extraction beneficiation process suitable for fine-grained magnetite ore. In this process, the tailings from the first and second stages of weak magnetic separation in the staged grinding and beneficiation process are directly used as the final tailings. The second-stage weak magnetic separation concentrate is fed into a reverse flotation operation. The reverse flotation operation employs a cationic collector reverse flotation process to obtain a portion of qualified iron concentrate in advance. The middlings obtained from the reverse flotation operation are then dewatered by magnetic separation and fed into a third-stage mill for regrinding—a third-stage weak magnetic separation yields a third-stage weak magnetic separation concentrate. The regrinding fineness of the middlings is -0.030mm with a content ≥88%. The third-stage weak magnetic separation concentrate and the portion of qualified iron concentrate obtained in advance by the reverse flotation operation are combined to form a comprehensive iron concentrate. The third-stage weak magnetic separation tailings are incorporated into the final tailings to obtain the total tailings. However, this beneficiation method is difficult to handle fine-grained, low-grade, difficult-to-beneficiate magnetite ores with a TFe grade of 25.0% to 30.0%, and the large flotation feed rate and fluctuations in ore properties and particle size distribution have a significant impact on production indicators.

[0006] This invention belongs to the field of low-grade magnetite ore beneficiation technology, specifically relating to a beneficiation method for staged grinding and staged separation of low-grade magnetite ore. It is particularly suitable for staged grinding and separation of fine-grained magnetite ore with a TFe grade of 25.0%~30.0%, an mFe grade of 15%~20.0%, and a grinding particle size of -0.038mm content of 90%~95% to achieve monomer liberation.

[0007] This invention discloses a high-efficiency beneficiation process combining stage grinding and magnetic flotation for fine-grained lean magnetite ore. The process involves: first, a secondary concentration treatment on the concentrate from three stages of weak magnetic separation; second, a secondary concentration stream passing through a magnetic separation column I for further cleaning; third, agitation of the concentrate from column I followed by reverse flotation to obtain a flotation concentrate; fourth, a quasi-concentration magnetic separator feeding the tailings and scavenging tailings from column I into a concentrated magnetic separator for further concentration; fifth, a concentrated magnetic concentrate undergoing three-stage grinding and three-stage classification to form a closed circuit, with hydrocyclones used in the three stages; and fifth, a tertiary weak magnetic separation process feeding the overflow from the hydrocyclones into a fifth-stage weak magnetic separator to obtain a fifth-stage weak magnetic concentrate; sixth, a tertiary concentration treatment on the fifth-stage weak magnetic concentrate; fourth, a secondary concentration stream passing through a magnetic separation column II for further cleaning; fifth, a secondary concentration stream passing through a concentration column V for further cleaning; and finally, a reverse flotation process to obtain a flotation concentrate. The two flotation concentrates are then combined to obtain the final total concentrate. This invention has the advantages of high iron concentrate grade, high magnetic iron recovery rate, low flotation feed amount, stable indicators, and strong applicability. Summary of the Invention

[0008] (a) Technical problems to be solved

[0009] To address the shortcomings of existing technologies, this invention provides a high-efficiency beneficiation process combining stage grinding and magnetic levitation for fine-grained lean magnetite ore, which solves the problems existing in the prior art.

[0010] (II) Technical Solution

[0011] To achieve the above objectives, the present invention provides the following technical solution: a high-efficiency beneficiation process combining stage grinding and magnetic levitation for fine-grained lean magnetite ore, the specific operation of which is as follows:

[0012] S1. Perform ore feeding operation;

[0013] S2. Perform grinding operation, then classify the ore, re-grind the large particles, and proceed to step S3 for the small particles.

[0014] S3. Perform weak magnetic separation 1. Qualified products proceed to step S4, while unqualified products are discharged as tailings.

[0015] S4. Perform concentration 1 operation. Concentrate the underflow and proceed to step S5. After the ore body is concentrated and classified, the large particles are ground. The overflow is discharged as tailings.

[0016] S5. Perform weak magnetic separation 2 operation, in which the overflow is discharged as tailings;

[0017] S6. Perform demagnetization, followed by weak magnetic separation 3, and discharge the unqualified products as tailings.

[0018] S7. Perform demagnetization and concentration 2, discharge the overflow, perform magnetic separation column 1 operation on the concentrated underflow, then proceed to step S12, perform concentration 3 operation on the remaining part, discharge the overflow, and then perform stirring operation on the product, adding NaOH, DF, CaO and MD during stirring.

[0019] S8. Perform reverse flotation roughing operation. Qualified products proceed to step S9, and unqualified products undergo sweeping operation. Qualified products after sweeping are repeated in step S7, and unqualified products proceed to step S12.

[0020] S9. Perform the selection 1 operation and add MD. Qualified products proceed to step S10, and unqualified products proceed to step S7.

[0021] S10. Perform the selection 2 operation and add MD. Qualified products will proceed to step S11, and unqualified products will proceed to step S9.

[0022] S11. Perform the selection 3 operation and add MD at the same time. The qualified products are output as concentrate, and the unqualified products are processed in step S10.

[0023] S12. Perform concentration and magnetic separation operation, and discharge the overflow.

[0024] S13. Perform grinding operation, followed by classification operation. After classification, large particles are processed in step S13 and small particles are processed in step S14.

[0025] S14. Perform weak magnetic separation 4. Unqualified products are discharged as tailings, and qualified products proceed to step S15.

[0026] S15. Perform demagnetization, followed by magnetic separation 5. Unqualified products are discharged as tailings, and qualified products proceed to step S16.

[0027] S16. Perform concentration 4 and demagnetization operations. Unqualified products are discharged as tailings, and qualified products are discharged in step S17. Overflow is discharged.

[0028] S17. Perform magnetic separation column 2 operation. Unqualified products are discharged as tailings, and qualified products proceed to step S18.

[0029] S18. Perform concentration step 5 and demagnetization step, and discharge the overflow.

[0030] S19. Perform stirring operation, adding NaOH, DF, CaO and MD during stirring;

[0031] S20. Perform reverse flotation coarse selection operation. Qualified products proceed to step S21, and unqualified products proceed to step S24.

[0032] S21. Perform the selection 1 operation and add MD. Proceed to step S22 for qualified products and step S18 for unqualified products.

[0033] S22. Perform the selection 2 operation and add MD. Proceed to step S23 for qualified products and step S21 for unqualified products.

[0034] S23. Perform the selection 3 operation and add MD at the same time. Qualified products are output as concentrate, and unqualified products are processed in step S22.

[0035] S24. Perform a sweeping operation. Qualified products proceed to step S18, while unqualified products are discharged as tailings.

[0036] Preferably, the staged grinding and staged separation beneficiation method involves crushing magnetite ore with a TFe grade in the range of 25.0%~30.0% and an mFe grade in the range of 15.0%~20.0%, and then processing it through a first-stage grinding, a first-stage weak magnetic separation-a second-stage grinding, a second-stage weak magnetic separation, and a third-stage weak magnetic separation. The tailings from the first-stage, second-stage, and third-stage weak magnetic separations are discharged to obtain a third-stage weak magnetic separation concentrate. A classification operation is performed between the first-stage grinding and the first-stage weak magnetic separation, and a second-stage classification operation is performed between the first-stage and second-stage grinding. Both the first-stage and second-stage grinding use grate-type ball mills, the first-stage, second-stage, and third-stage weak magnetic separations all use drum-type wet weak magnetic separators, and both the first-stage and second-stage classification operations use spiral classifiers.

[0037] Preferably, in the entire process, the concentrate from the three weak magnetic separations is concentrated in a second stage, the concentrated underflow is then cleaned in a magnetic separation column I, and the concentrate from the magnetic separation column I is concentrated in a third stage and stirred before being subjected to reverse flotation. The reverse flotation includes roughing, cleaning and scavenging in sequence to obtain flotation concentrate.

[0038] The tailings and scavenging tailings from the magnetic separation column I are fed into the thickening magnetic separator for thickening and magnetic separation. The thickened magnetic separation tailings are discharged, and thickened magnetic separation concentrate is obtained.

[0039] The concentrated magnetic separation concentrate is processed through three stages of grinding and three stages of classification to form a closed circuit. The three stages of classification use hydrocyclones. The overflow of the hydrocyclones is fed into the fourth and fifth weak magnetic separation stages, and the tailings of the fourth and fifth weak magnetic separation stages are discharged to obtain the fifth weak magnetic separation concentrate.

[0040] The concentrate from the five weak magnetic separation processes is concentrated in the IV stage. The concentrated underflow is then cleaned in the II magnetic separation column. The concentrate from the II magnetic separation column is then concentrated in the V stage and stirred before being subjected to reverse flotation, which includes roughing, cleaning and scavenging processes to obtain flotation concentrate.

[0041] The concentrates from the two flotation processes are combined into a final total concentrate with a TFe grade > 64.0% and an mFe recovery rate > 85.0%; the tailings from the first, second, third, fourth, and fifth magnetic separation processes are combined into a total tailings.

[0042] Preferably, the particle size of the first-stage grinding is in the range of 50%~55% -0.076mm, and the particle size of the second-stage grinding is in the range of 90%~95% -0.076mm; the magnetic field strength of the first weak magnetic separation operation is 0.18T; the magnetic field strength of the second weak magnetic separation operation is 0.16~0.19T, and the magnetic field strength of the third weak magnetic separation operation is 0.12~0.15T;

[0043] The reverse flotation operation consists of one roughing, one scavenging, and three cleaning processes. The product in the tank after the third cleaning is the final iron concentrate. The tailings from the cleaning process I and the flotation scavenging concentrate are returned to the concentration process III.

[0044] The magnetic field strength of the concentration magnetic separator is 0.18~0.21T; in step (3), the overflow particle size of the hydrocyclone is 90%~95% of -0.038mm, the magnetic field strength of the four weak magnetic separation operations is 0.16~0.19T, and the magnetic field strength of the five weak magnetic separation operations is 0.12~0.15T.

[0045] Preferably, the reverse flotation operation consists of one roughing, one scavenging, and three cleaning processes. The product in the tank after the third cleaning is the final iron concentrate, and the tailings from the cleaning process I and the flotation scavenging concentrate are returned to the concentration V.

[0046] The reverse flotation operation uses an anionic reverse flotation collector MD, which is prepared by chelation and saponification reaction of organic acid and chelating agent. The acid value (mgKOH / g) is 90-210, the saponification value (mgKOH / g) is 90-210, and the iodine value is 100-120. The activator used is CaO, the inhibitor used is starch, and the modifier used is NaOH.

[0047] Preferably, the concentration of the reverse flotation rougher is in the range of 30-35%, and the temperature of the reverse flotation pulp is between 31-36℃; based on the dry ore feed rate, the amount of collector MD used in the reverse flotation rougher is 250-400 g / t, the amount of CaO is 50-100 g / t, the amount of starch is 100-300 g / t, and the amount of NaOH is 350-550 g / t; the amount of collector MD used in the reverse flotation cleaner is 50-100 g / t; and no reagents are added in the reverse flotation scavenging.

[0048] The reverse flotation operation uses anionic reverse flotation collector MD; the activator is CaO; the depressant is starch; and the modifier is NaOH. The roughing concentration of the reverse flotation is in the range of 30-35%, and the pulp temperature is between 31-36℃. Based on the dry ore feed, the dosage of collector MD in the roughing stage is 125-250 g / t, the dosage of CaO is 50-100 g / t, the dosage of starch is 150-300 g / t, and the dosage of NaOH is 350-550 g / t. The dosage of collector MD in the cleaning stage is 50-100 g / t. No reagents are added during the scavenging stage of the reverse flotation.

[0049] (III) Beneficial Effects

[0050] This invention provides a high-efficiency mineral processing technology combining staged grinding and magnetic levitation for fine-grained, low-grade magnetite ore. It offers the following advantages:

[0051] (1) In this invention, after two-stage grinding-weak magnetic separation-magnetic separation column I and three-stage grinding-weak magnetic separation-magnetic separation column II, the concentrate from the magnetic separation column is separately fed into an independent flotation system to obtain qualified iron concentrate products with individual liberation. This reduces the impact of large differences in particle size composition and selectivity on the grade of iron concentrate and is conducive to improving the iron grade of concentrate.

[0052] (2) The present invention sets up a magnetic separation column before flotation, which not only improves the flotation grade, but also coarseens the grinding particle size. At the same time, the process adaptability is greatly enhanced, and the fluctuation of ore properties within a certain range has little effect on production indicators.

[0053] (3) Reverse flotation to obtain fines in advance reduces the feed amount of the three-stage ball mill, greatly reduces grinding costs, and achieves the goal of reducing energy consumption and increasing efficiency.

[0054] (4) The present invention performs magnetic separation-flotation after two-stage grinding, and then re-grinds and performs magnetic separation and flotation on middlings, which reduces the amount of closed-loop return in the process, facilitates on-site operation and control, and results in small fluctuations in indicators.

[0055] (5) The present invention is stable in operation and simple and easy to operate in production. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the process of the present invention;

[0057] Figure 2 The results of the raw ore analysis are shown in the embodiments of the present invention. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Please see Figure 1-2 This invention provides a technical solution: a high-efficiency mineral processing technology combining stage grinding and magnetic levitation for fine-grained lean magnetite ore, the specific operation of which is as follows:

[0060] S1. Perform ore feeding operation;

[0061] S2. Perform grinding operation, then classify the ore, re-grind the large particles, and proceed to step S3 for the small particles.

[0062] S3. Perform weak magnetic separation 1. Qualified products proceed to step S4, while unqualified products are discharged as tailings.

[0063] S4. Perform concentration 1 operation. Concentrate the underflow and proceed to step S5. After the ore body is concentrated and classified, the large particles are ground. The overflow is discharged as tailings.

[0064] S5. Perform weak magnetic separation 2 operation, in which the overflow is discharged as tailings;

[0065] S6. Perform demagnetization, followed by weak magnetic separation 3, and discharge the unqualified products as tailings.

[0066] S7. Perform demagnetization and concentration 2, discharge the overflow, perform magnetic separation column 1 operation on the concentrated underflow, then proceed to step S12, perform concentration 3 operation on the remaining part, discharge the overflow, and then perform stirring operation on the product, adding NaOH, DF, CaO and MD during stirring.

[0067] S8. Perform reverse flotation roughing operation. Qualified products proceed to step S9, and unqualified products undergo sweeping operation. Qualified products after sweeping are repeated in step S7, and unqualified products proceed to step S12.

[0068] S9. Perform the selection 1 operation and add MD. Qualified products proceed to step S10, and unqualified products proceed to step S7.

[0069] S10. Perform the selection 2 operation and add MD. Qualified products will proceed to step S11, and unqualified products will proceed to step S9.

[0070] S11. Perform the selection 3 operation and add MD at the same time. The qualified products are output as concentrate, and the unqualified products are processed in step S10.

[0071] S12. Perform concentration and magnetic separation operation, and discharge the overflow.

[0072] S13. Perform grinding operation, followed by classification operation. After classification, large particles are processed in step S13 and small particles are processed in step S14.

[0073] S14. Perform weak magnetic separation 4. Unqualified products are discharged as tailings, and qualified products proceed to step S15.

[0074] S15. Perform demagnetization, followed by magnetic separation 5. Unqualified products are discharged as tailings, and qualified products proceed to step S16.

[0075] S16. Perform concentration 4 and demagnetization operations. Unqualified products are discharged as tailings, and qualified products are discharged in step S17. Overflow is discharged.

[0076] S17. Perform magnetic separation column 2 operation. Unqualified products are discharged as tailings, and qualified products proceed to step S18.

[0077] S18. Perform concentration step 5 and demagnetization step, and discharge the overflow.

[0078] S19. Perform stirring operation, adding NaOH, DF, CaO and MD during stirring;

[0079] S20. Perform reverse flotation coarse selection operation. Qualified products proceed to step S21, and unqualified products proceed to step S24.

[0080] S21. Perform the selection 1 operation and add MD. Proceed to step S22 for qualified products and step S18 for unqualified products.

[0081] S22. Perform the selection 2 operation and add MD. Proceed to step S23 for qualified products and step S21 for unqualified products.

[0082] S23. Perform the selection 3 operation and add MD at the same time. Qualified products are output as concentrate, and unqualified products are processed in step S22.

[0083] S24. Perform a sweeping operation. Qualified products proceed to step S18, while unqualified products are discharged as tailings.

[0084] The described staged grinding and staged separation beneficiation method involves crushing magnetite ore with a TFe grade ranging from 25.0% to 30.0% and an mFe grade ranging from 15.0% to 20.0%, and then processing it through a first-stage grinding, a first-stage weak magnetic separation followed by a second-stage grinding, a second-stage weak magnetic separation, and a third-stage weak magnetic separation. The tailings from the first, second, and third stages of weak magnetic separation are discharged to obtain a third-stage weak magnetic separation concentrate. A classification operation is performed between the first-stage grinding and the first-stage weak magnetic separation, and a second-stage classification operation is performed between the first-stage and the second-stage grinding. Both the first-stage and second-stage grinding utilize grate-type ball mills. The first, second, and third stages of weak magnetic separation all employ drum-type wet weak magnetic separators. The first-stage and second-stage classification operations both utilize spiral classifiers.

[0085] In the entire process, the concentrate from the three weak magnetic separations is concentrated in the second stage. The concentrated underflow is then cleaned in the first magnetic separation column. The concentrate from the first magnetic separation column is then concentrated in the third stage and stirred before being subjected to reverse flotation. The reverse flotation includes roughing, cleaning and scavenging in sequence to obtain flotation concentrate.

[0086] The tailings and scavenging tailings from the magnetic separation column I are fed into the thickening magnetic separator for thickening and magnetic separation. The thickened magnetic separation tailings are discharged, and thickened magnetic separation concentrate is obtained.

[0087] The concentrated magnetic separation concentrate is processed through three stages of grinding and three stages of classification to form a closed circuit. The three stages of classification use hydrocyclones. The overflow of the hydrocyclones is fed into the fourth and fifth weak magnetic separation stages, and the tailings of the fourth and fifth weak magnetic separation stages are discharged to obtain the fifth weak magnetic separation concentrate.

[0088] The concentrate from the five weak magnetic separation processes is concentrated in the IV stage. The concentrated underflow is then cleaned in the II magnetic separation column. The concentrate from the II magnetic separation column is then concentrated in the V stage and stirred before being subjected to reverse flotation, which includes roughing, cleaning and scavenging processes to obtain flotation concentrate.

[0089] The concentrates from the two flotation processes are combined into a final total concentrate with a TFe grade > 64.0% and an mFe recovery rate > 85.0%; the tailings from the first, second, third, fourth, and fifth magnetic separation processes are combined into a total tailings.

[0090] The first-stage grinding particle size is in the range of 50%~55% -0.076mm, and the second-stage grinding particle size is in the range of 90%~95% -0.076mm; the magnetic field strength of the first weak magnetic separation operation is 0.18T; the magnetic field strength of the second weak magnetic separation operation is 0.16~0.19T, and the magnetic field strength of the third weak magnetic separation operation is 0.12~0.15T;

[0091] The reverse flotation operation consists of one roughing, one scavenging, and three cleaning processes. The product in the tank after the third cleaning is the final iron concentrate. The tailings from the cleaning process I and the flotation scavenging concentrate are returned to the concentration process III.

[0092] The magnetic field strength of the concentration magnetic separator is 0.18~0.21T; in step (3), the overflow particle size of the hydrocyclone is 90%~95% of -0.038mm, the magnetic field strength of the four weak magnetic separation operations is 0.16~0.19T, and the magnetic field strength of the five weak magnetic separation operations is 0.12~0.15T.

[0093] The reverse flotation operation consists of one roughing, one scavenging, and three cleaning processes. The product in the tank after the third cleaning is the final iron concentrate. The tailings from the cleaning process I and the flotation scavenging concentrate are returned to the concentration V.

[0094] The reverse flotation operation uses an anionic reverse flotation collector MD, which is prepared by chelation and saponification reaction of organic acid and chelating agent. The acid value (mgKOH / g) is 90-210, the saponification value (mgKOH / g) is 90-210, and the iodine value is 100-120. The activator used is CaO, the inhibitor used is starch, and the modifier used is NaOH.

[0095] The reverse flotation roughing concentration is in the range of 30-35%, and the reverse flotation pulp temperature is between 31-36℃. Based on the dry ore feed rate, the amount of collector MD used in the reverse flotation roughing is 250-400 g / t, the amount of CaO is 50-100 g / t, the amount of starch is 100-300 g / t, and the amount of NaOH is 350-550 g / t. The amount of collector MD used in the reverse flotation cleaning is 50-100 g / t. No reagents are added in the reverse flotation scavenging.

[0096] The reverse flotation operation uses anionic reverse flotation collector MD; the activator is CaO; the depressant is starch; and the modifier is NaOH. The roughing concentration of the reverse flotation is in the range of 30-35%, and the pulp temperature is between 31-36℃. Based on the dry ore feed, the dosage of collector MD in the roughing stage is 125-250 g / t, the dosage of CaO is 50-100 g / t, the dosage of starch is 150-300 g / t, and the dosage of NaOH is 350-550 g / t. The dosage of collector MD in the cleaning stage is 50-100 g / t. No reagents are added during the scavenging stage of the reverse flotation.

[0097] Example:

[0098] To describe the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, provides a high-efficiency mineral processing technology for staged grinding and magnetic levitation of fine-grained lean magnetite ore.

[0099] The fine-grained magnetite ore raw material came from a magnetite beneficiation plant in East my country. The results of the multi-element chemical analysis of the processed magnetite ore are shown below. Figure 2 ;

[0100] The raw magnetite ore has a TFe grade of 27.50% and a mFe grade of 18.21%. The S and P contents in the ore are not high, and the main impurity is SiO2. The main industrial iron mineral in the ore is magnetite, with mFe / TFe = 66.41% and (CaO+MgO) / (SiO2+Al2O3) = 0.093, classifying it as an acidic iron ore.

[0101] Depend on Figure 1 The schematic diagram of the high-efficiency beneficiation process for fine-grained lean magnetite ore staged grinding-magnetic levitation combined process of the present invention shows that the process includes the following steps:

[0102] (1) The magnetite ore undergoes a series of processes, including grinding, classification, weak magnetic separation, pre-classification, grinding, weak magnetic separation, and tertiary weak magnetic separation. Tailings from the first, second, and third weak magnetic separations are discharged to obtain a tertiary weak magnetic separation concentrate. Both grinding and classification use grate-type ball mills. Drum-type wet weak magnetic separators are used for the first, second, and third weak magnetic separations. Spiral classifiers are used for both classification and classification operations. The grinding particle size is controlled at 55% and 90% of the -0.076mm particle size mass content, respectively, for the first and second stages. The magnetic field strength for the first weak magnetic separation is 0.18T. The magnetic field strength for the second weak magnetic separation is 0.18T, and the magnetic field strength for the tertiary weak magnetic separation is 0.14T.

[0103] (2) The three weak magnetic separation concentrates are concentrated in the second stage. The concentrated underflow is then cleaned in the magnetic separation column I. The magnetic separation column I concentrate is then concentrated in the third stage and stirred before being subjected to reverse flotation. The reverse flotation operation consists of one roughing, one scavenging, and three cleaning stages. The product in the tank after the third cleaning is the final iron concentrate. The tailings from the cleaning stage I and the flotation scavenging concentrate are returned to the concentration stage III. The reverse flotation operation uses an anionic reverse flotation collector MD, which is prepared by chelation and saponification reaction of organic acid and chelating agent. The acid value (mgKOH / g) is 90-210, the saponification value (mgKOH / g) is 90-210, and the iodine value is 100-120. The activator used is CaO; the depressant used is starch; and the modifier used is NaOH. The roughing concentration in the reverse flotation is in the range of 30-35%, and the pulp temperature is 35℃. Based on the dry ore feed, the dosage of collector MD in the roughing stage is 337 g / t, the dosage of CaO is 78 g / t, the dosage of starch is 160 g / t, and the dosage of NaOH is 495 g / t. The dosage of collector MD in the cleaning stage is 63 g / t. No reagents are added during the scavenging stage of the reverse flotation.

[0104] (3) The tailings and scavenging tailings from the magnetic separation column I are fed into the thickening magnetic separator for thickening magnetic separation, the thickened magnetic separation tailings are discharged, and thickened magnetic separation concentrate is obtained; the magnetic field strength of the thickening magnetic separator is 0.20T.

[0105] (4) The concentrated magnetic separation concentrate is processed by three-stage grinding and three-stage classification to form a closed circuit. The three-stage classification adopts hydrocyclones. The overflow of the hydrocyclones is fed into the fourth and fifth weak magnetic separations, and the tailings of the fourth and fifth weak magnetic separations are discharged to obtain the fifth weak magnetic separation concentrate. The overflow particle size of the hydrocyclones is 90%~95% of -0.038mm. The magnetic field strength of the fourth weak magnetic separation is 0.18T, and the magnetic field strength of the fifth weak magnetic separation is 0.14T.

[0106] (5) The five weak magnetic separation concentrates are concentrated into IV. The concentrated underflow is then cleaned by magnetic separation column II. The magnetic separation column II concentrate is concentrated into V and stirred before being subjected to reverse flotation. The reverse flotation includes one roughing, three cleaning and one scavenging. The product in the tank after the third cleaning is the final iron concentrate. The tailings of cleaning I and the flotation scavenging concentrate are returned to concentration V. The reverse flotation operation uses an anionic reverse flotation collector MD, which is prepared by chelation and saponification reaction of organic acid and chelating agent. The acid value (mgKOH / g) is 90-210, the saponification value (mgKOH / g) is 90-210, and the iodine value is 100-120. The activator used is CaO; the depressant used is starch; and the modifier used is NaOH. The roughing concentration in the reverse flotation is in the range of 30-35%, and the pulp temperature is 35℃. Based on the dry ore feed, the dosage of collector MD in the roughing stage is 170 g / t, the dosage of CaO is 78 g / t, the dosage of starch is 210 g / t, and the dosage of NaOH is 495 g / t. The dosage of collector MD in the cleaning stage is 62 g / t. No reagents are added during the scavenging stage.

[0107] (6) The concentrates from the two flotation processes are combined into a final total concentrate, and the tailings from the first, second, third, fourth, and fifth magnetic separation processes are combined into a total tailings. The total concentrate obtained has a TFe grade > 64.0% and an mFe recovery rate > 85.0%.

[0108] Following the above process and steps, the fine-grained low-grade magnetite ore was beneficiated to obtain an iron concentrate yield of 24.05%, a TFe grade of 64.89%, an iron recovery rate of 56.76%, a magnetic iron recovery rate of over 85.28%, and a final total tailings of 15.66%.

[0109] In summary, this high-efficiency beneficiation process combining stage grinding and magnetic levitation for fine-grained lean magnetite ore has the following advantages:

[0110] (1) In this invention, after two-stage grinding-weak magnetic separation-magnetic separation column I and three-stage grinding-weak magnetic separation-magnetic separation column II, the concentrate from the magnetic separation column is separately fed into an independent flotation system to obtain qualified iron concentrate products with individual liberation. This reduces the impact of large differences in particle size composition and selectivity on the grade of iron concentrate and is conducive to improving the iron grade of concentrate.

[0111] (2) The present invention sets up a magnetic separation column before flotation, which not only improves the flotation grade, but also coarseens the grinding particle size. At the same time, the process adaptability is greatly enhanced, and the fluctuation of ore properties within a certain range has little effect on production indicators.

[0112] (3) Reverse flotation to obtain fines in advance reduces the feed amount of the three-stage ball mill, greatly reduces grinding costs, and achieves the goal of reducing energy consumption and increasing efficiency.

[0113] (4) The present invention performs magnetic separation-flotation after two-stage grinding, and then re-grinds and performs magnetic separation and flotation on middlings, which reduces the amount of closed-loop return in the process, facilitates on-site operation and control, and results in small fluctuations in indicators.

[0114] (5) The present invention is stable in operation and simple and easy to operate in production.

[0115] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0116] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency beneficiation process combining stage grinding and magnetic levitation for fine-grained lean magnetite ore, characterized in that: The specific steps are as follows: S1. Perform ore feeding operation; S2. Perform grinding operation, then classify the ore, re-grind the large particles, and proceed to step S3 for the small particles. S3. Perform weak magnetic separation 1. Qualified products proceed to step S4, while unqualified products are discharged as tailings. S4. Perform concentration 1 operation. Concentrate the underflow and proceed to step S5. After the ore body is concentrated and classified, the large particles are ground. The overflow is discharged as tailings. S5. Perform weak magnetic separation 2 operation, in which the overflow is discharged as tailings; S6. Perform demagnetization, followed by weak magnetic separation 3, and discharge the unqualified products as tailings. S7. Perform demagnetization and concentration 2, discharge the overflow, perform magnetic separation column 1 operation on the concentrated underflow, then proceed to step S12, perform concentration 3 operation on the remaining part, discharge the overflow, and then perform stirring operation on the product, adding NaOH, DF, CaO and MD during stirring. S8. Perform reverse flotation roughing operation. Qualified products proceed to step S9, and unqualified products undergo sweeping operation. Qualified products after sweeping are repeated in step S7, and unqualified products proceed to step S12. S9. Perform the selection 1 operation and add MD. Qualified products proceed to step S10, and unqualified products proceed to step S7. S10. Perform the selection 2 operation and add MD. Qualified products will proceed to step S11, and unqualified products will proceed to step S9. S11. Perform the selection 3 operation and add MD at the same time. The qualified products are output as concentrate, and the unqualified products are processed in step S10. S12. Perform concentration magnetic separation operation and discharge the overflow; S13. Perform grinding operation, followed by classification operation. After classification, large particles are processed in step S13 and small particles are processed in step S14. S14. Perform weak magnetic separation 4. Unqualified products are discharged as tailings, and qualified products proceed to step S15. S15. Perform demagnetization, followed by magnetic separation 5. Unqualified products are discharged as tailings, and qualified products proceed to step S16. S16. Perform concentration 4 and demagnetization operations. Unqualified products are discharged as tailings, and qualified products are discharged in step S17. Overflow is discharged. S17. Perform magnetic separation column 2 operation. Unqualified products are discharged as tailings, and qualified products proceed to step S18. S18. Perform concentration step 5 and demagnetization steps, and discharge the overflow. S19. Perform stirring operation, adding NaOH, DF, CaO and MD during stirring; S20. Perform reverse flotation coarse selection operation. Qualified products proceed to step S21, and unqualified products proceed to step S24. S21. Perform the selection 1 operation and add MD. Proceed to step S22 for qualified products and step S18 for unqualified products. S22. Perform the selection 2 operation and add MD. Proceed to step S23 for qualified products and step S21 for unqualified products. S23. Perform the selection 3 operation and add MD at the same time. Qualified products are output as concentrate, and unqualified products are processed in step S22. S24. Perform a sweeping operation. Qualified products proceed to step S18, while unqualified products are discharged as tailings.

2. The high-efficiency beneficiation process for fine-grained lean magnetite ore through staged grinding and magnetic levitation as described in claim 1, characterized in that: The described staged grinding and staged separation beneficiation method involves crushing magnetite ore with a TFe grade ranging from 25.0% to 30.0% and an mFe grade ranging from 15.0% to 20.0%, and then processing it through a first-stage grinding, a first-stage weak magnetic separation followed by a second-stage grinding, a second-stage weak magnetic separation, and a third-stage weak magnetic separation. The tailings from the first, second, and third stages of weak magnetic separation are discharged to obtain a third-stage weak magnetic separation concentrate. A classification operation is performed between the first-stage grinding and the first-stage weak magnetic separation, and a second-stage classification operation is performed between the first-stage and the second-stage grinding. Both the first-stage and second-stage grinding utilize grate-type ball mills. The first, second, and third stages of weak magnetic separation all employ drum-type wet weak magnetic separators. The first-stage and second-stage classification operations both utilize spiral classifiers.

3. The high-efficiency beneficiation process for fine-grained lean magnetite ore through staged grinding and magnetic levitation as described in claim 1, characterized in that: In the entire process, the concentrate from the three weak magnetic separations is concentrated in the second stage. The concentrated underflow is then cleaned in the first magnetic separation column. The concentrate from the first magnetic separation column is then concentrated in the third stage and stirred before being subjected to reverse flotation. The reverse flotation includes roughing, cleaning and scavenging in sequence to obtain flotation concentrate. The tailings and scavenging tailings from the magnetic separation column I are fed into the thickening magnetic separator for thickening and magnetic separation. The thickened magnetic separation tailings are discharged, and thickened magnetic separation concentrate is obtained. The concentrated magnetic separation concentrate is processed through three stages of grinding and three stages of classification to form a closed circuit. The three stages of classification use hydrocyclones. The overflow of the hydrocyclones is fed into the fourth and fifth weak magnetic separation stages, and the tailings of the fourth and fifth weak magnetic separation stages are discharged to obtain the fifth weak magnetic separation concentrate. The concentrate from the five weak magnetic separation processes is concentrated in the IV stage. The concentrated underflow is then cleaned in the II magnetic separation column. The concentrate from the II magnetic separation column is then concentrated in the V stage and stirred before being subjected to reverse flotation, which includes roughing, cleaning and scavenging processes to obtain flotation concentrate. The concentrates from the two flotation processes are combined into a final total concentrate with a TFe grade > 64.0% and an mFe recovery rate > 85.0%; the tailings from the first, second, third, fourth, and fifth magnetic separation processes are combined into a total tailings.

4. The high-efficiency beneficiation process for fine-grained lean magnetite ore through staged grinding and magnetic levitation as described in claim 1, characterized in that: The first-stage grinding particle size is in the range of 50%~55% -0.076mm, and the second-stage grinding particle size is in the range of 90%~95% -0.076mm; the magnetic field strength of the first weak magnetic separation operation is 0.18T; the magnetic field strength of the second weak magnetic separation operation is 0.16~0.19T, and the magnetic field strength of the third weak magnetic separation operation is 0.12~0.15T; The reverse flotation operation consists of one roughing, one scavenging, and three cleaning processes. The product in the tank after the third cleaning is the final iron concentrate. The tailings from the cleaning process I and the flotation scavenging concentrate are returned to the concentration process III. The magnetic field strength of the concentration magnetic separator is 0.18~0.21T; in step (3), the overflow particle size of the hydrocyclone is 90%~95% of -0.038mm, the magnetic field strength of the four weak magnetic separation operations is 0.16~0.19T, and the magnetic field strength of the five weak magnetic separation operations is 0.12~0.15T.

5. The high-efficiency beneficiation process for fine-grained lean magnetite ore through staged grinding and magnetic levitation as described in claim 1, characterized in that: The reverse flotation operation consists of one roughing, one scavenging, and three cleaning processes. The product in the tank after the third cleaning is the final iron concentrate. The tailings from the cleaning process I and the flotation scavenging concentrate are returned to the concentration V. The reverse flotation operation uses an anionic reverse flotation collector MD, which is prepared by chelation and saponification reaction of organic acid and chelating agent. The acid value (mgKOH / g) is 90-210, the saponification value (mgKOH / g) is 90-210, and the iodine value is 100-120. The activator used is CaO, the inhibitor used is starch, and the modifier used is NaOH.

6. The high-efficiency beneficiation process for fine-grained lean magnetite ore through staged grinding and magnetic levitation as described in claim 1, characterized in that: The reverse flotation roughing concentration is in the range of 30-35%, and the reverse flotation pulp temperature is between 31-36℃. Based on the dry ore feed rate, the amount of collector MD used in the reverse flotation roughing is 250-400 g / t, the amount of CaO is 50-100 g / t, the amount of starch is 100-300 g / t, and the amount of NaOH is 350-550 g / t. The amount of collector MD used in the reverse flotation cleaning is 50-100 g / t. No reagents are added in the reverse flotation scavenging. The reverse flotation operation uses anionic reverse flotation collector MD; the activator is CaO; the depressant is starch; and the modifier is NaOH. The roughing concentration of the reverse flotation is in the range of 30-35%, and the pulp temperature is between 31-36℃. Based on the dry ore feed, the dosage of collector MD in the roughing stage is 125-250 g / t, the dosage of CaO is 50-100 g / t, the dosage of starch is 150-300 g / t, and the dosage of NaOH is 350-550 g / t. The dosage of collector MD in the cleaning stage is 50-100 g / t. No reagents are added during the scavenging stage of the reverse flotation.

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