A pre-concentration process for a mixed magnetite deposit

Abstract

The application provides a strong and weak magnetic mixed iron ore preselection process and relates to the technical field of mineral processing. The strong and weak magnetic mixed iron ore preselection process is a composite separation mode of dry magnetic separation+photoelectric sorting, and the composite separation mode needs to be cooperatively carried out in cooperation with a crushing mode; specifically, first, the granularity of the raw ore is crushed to the most suitable separation granularity for dry magnetic separation and photoelectric sorting, and then the strong and weak magnetic iron ore in the mixed iron ore is recovered through dry magnetic separation and photoelectric sorting technology respectively. The strong magnetic iron concentrate is first separated and then the weak magnetic iron concentrate is separated through the cooperative use of the dry magnetic separation waste throwing and the ore particle photoelectric sorting technology, and the separation process needs to cooperate with the judgment condition "r2>=r4" to select the crushing section number and the corresponding particle size selection. The method has the advantages of low cost, high efficiency, simple influencing factors, convenient simulation calculation results, wide application range, and is beneficial to industrial production practice and large-scale promotion.

Description

Technical Field

[0001] This invention relates to the technical field of mineral processing, and in particular to a pre-selection process for iron ore with strong and weak magnetic properties. Background Technology

[0002] In existing technologies, pre-selection waste disposal technology can significantly improve the grade of feed ore, broaden the mineable boundaries of deposits, and enhance the production efficiency of mining enterprises. Among these, dry magnetic separation waste disposal is currently the main method for processing magnetite due to its large processing capacity and high separation efficiency. However, when applying this method to process strongly and weakly magnetic mixed iron ores, it leads to a significant loss of weakly magnetic iron minerals. Therefore, there is a need for a pre-selection waste disposal technology specifically for strongly and weakly magnetic mixed iron ores, which has not yet been widely adopted.

[0003] For example, Chinese patent CN106824517A discloses a dry pre-separation method for iron ore with strong magnetic and weak magnetic properties. It adopts multi-stage magnetic asynchronous separation using a combination of upward suction dry separation and high magnetic force strong magnetic separation. The device has a complex structure, is difficult to operate, consumes a lot of energy, and has high cost. It only requires a crushing stage, has poor separation effect, and low efficiency.

[0004] Chinese patent CN115155793A discloses a method for efficient cascade separation of mixed iron ore, which obviously uses a magnetic-repetitive force field separator for separation. However, the method has technical defects in the step-by-step cascade recovery of iron minerals with different magnetic susceptibility ratios, such as complex device structure, high operation difficulty, poor recovery efficiency, mixing of different magnetic properties in the recovered iron minerals, and loss of iron minerals.

[0005] Chinese patent CN 114308370A discloses a mixed iron ore grinding and magnetic separation upgrading and sand making process. This process separates difficult-to-process mixed iron ore containing magnetite, hematite, siderite, etc., using an internal cyclone magnetic separator after a first-stage grinding. The optimized external magnetic system structure of the magnetic separator simultaneously separates magnetite, hematite, and siderite. Obviously, separation is carried out by internal and external magnetic separators. However, the pre-disposal of coarse-grained tailings and gangue impurities in the ore entering the grinding mill results in iron ore loss. The magnetic separation process is difficult to control and is not suitable for large-scale processing.

[0006] Chinese patent CN109201321A discloses a separation process for processing magnetic-hematite mixed ore, which involves separation through a closed-circuit grinding stage, a weak magnetic operation stage, a two-stage closed-circuit grinding stage, a weak magnetic operation or a weak magnetic fine screening operation for magnetic ore, a strong magnetic grinding and strong magnetic operation, a reverse flotation operation, and a shaking table operation. Obviously, the process is long and inefficient, and the method of performing the weak magnetic operation first and then the strong magnetic operation will result in poor separation effect.

[0007] Although photoelectric separation of ore particles can collect images, X-ray response signals, infrared images, fluorescence characteristics and density characteristics of different ore particles through various sensors, and realize the classification, identification and separation of ore particles of different types and grades, it is mainly widely used in the pre-selection process of non-ferrous, ferrous and precious metal ores. However, due to its unique discrete material distribution method, photoelectric separation of ore particles cannot realize the large-scale processing of pre-selection of iron ore with strong and weak magnetic mixing.

[0008] Chinese patent CN111841871A discloses a beneficiation method for low-grade tungsten ore. This method employs a combined process including crushing and screening, photoelectric separation, fine crushing and screening, grinding, and dual-temperature flotation, with three-stage tailings removal to obtain qualified tungsten concentrate. Clearly, this method targets tungsten ore, and the purpose of separation is to discard approximately 27.265% of the total weight of waste rock. The technical effect is to reduce the amount of ore entering the grinding and flotation process, thereby increasing the grade of the ore entering the grinding and flotation process by approximately two times. However, this method cannot be used alone for large-scale pre-concentration of strongly and weakly magnetic mixed iron ore.

[0009] Therefore, there is an urgent need for a large-scale pre-selection and waste disposal technology for mixed iron ores with strong and weak magnetic properties. Summary of the Invention

[0010] The technical problem to be solved by this invention is that most current pre-selection methods for weakly magnetic mixed iron ore use internal and external magnetic separators for separation, and some use segmented magnetic separation and photoelectric separation + dual-temperature flotation. However, these methods have more or less technical defects such as complex separation device structure, high operation difficulty, high cost, low efficiency, poor accuracy, inclusions in the separated minerals, and difficulty in judging whether the optimal economic benefit indicators have been achieved.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0012] A pre-selection process for iron ore with strong and weak magnetic properties is disclosed. This process is a composite separation method combining dry magnetic separation and photoelectric sorting. The composite separation method needs to be coordinated with crushing. The specific steps are as follows:

[0013] S1, Obtain the particle size "+r1-r2" that maximizes the benefits of dry magnetic separation;

[0014] S2, Obtain the particle size "+r3-r4" that maximizes the benefits of photoelectric picking;

[0015] S3. Determine whether the condition “r2≥r4” is true;

[0016] S4. If the condition “r2≥r4” in S3 is met, the pre-selection process adopts two-stage crushing. The optimal particle size of the first stage crushing before dry magnetic separation is r2, and the optimal particle size of the second stage crushing before photoelectric sorting is r4.

[0017] S5. If condition "r2≥r4" in S3 does not hold, the pre-selection process employs a crushing stage before dry magnetic separation. The total benefit of dry magnetic separation and photoelectric sorting is NMR. 总 NMR 总 The grain size corresponding to the maximum value "+r" n -r m The optimal sorting particle size and optimal crushing particle size is r. m .

[0018] Preferably, the particle size "+r1-r2" that yields the greatest benefit from dry magnetic separation in S1 is obtained in the following way:

[0019] S101. Select a sufficient amount of raw ore sample and screen the ore into n1 different particle sizes according to the upper limit R1 and lower limit R2 of the sample particle size.

[0020] S102. Simulated dry magnetic separation test was conducted on n1 ore samples of different particle sizes from S101 to obtain the results of the simulated dry magnetic separation test.

[0021] S103. Based on the simulated dry magnetic separation test results in S102, calculate the NMR (Neural Magnetic Reduction) index for dry magnetic separation at n1 different particle sizes. 干式磁选 Determine the particle size "+r1-r2" corresponding to the maximum dry magnetic separation benefit value.

[0022] Preferably, in S101, the ratio of the upper and lower limits of the particle size of the n1 different particle sizes is not greater than 3:1.

[0023] Preferably, in S102, the simulated dry magnetic separation test considers ore blocks with an mFe content ≥30% as dry magnetic separation concentrate; this is because when the mFe content in the ore block is ≥30%, the ore block can be attracted by the magnetic poles of the weak magnetic dry magnetic separator, causing it to separate from other ore blocks and become dry magnetic separation concentrate.

[0024] Preferably, in S103, based on the simulated dry magnetic separation test results in S102, the mass m, yield γ, grade β, recovery rate ε, and other data of the dry magnetic separation concentrate for each particle size are statistically analyzed, and the dry magnetic separation benefit index NMR for each particle size is calculated. 干式磁选 Yield γ, grade β, recovery ε, and NMR of dry magnetic separation concentrates of various particle sizes. 干式磁选 The calculation formulas are shown in equations (1)-(4) respectively. When NMR 干式磁选 The particle size corresponding to the maximum value is the optimal particle size for dry magnetic separation;

[0025]

[0026] Where γ represents the concentrate yield of the simulated dry magnetic separation test, m iThe mass of the i-th ore particle is represented by k, which represents the number of ore particles with an mFe content ≥ 30%; and the total number of ore particles of this size range is represented by n.

[0027]

[0028] Where β represents the concentrate grade in the simulated dry magnetic separation test, m i x represents the mass of the i-th ore particle. i represents the grade of the i-th ore particle; k represents the number of ore particles with mFe content ≥ 30%;

[0029]

[0030] Where ε represents the recovery rate of the simulated dry magnetic separation test, m i x represents the mass of the i-th ore particle. i The grade of the i-th ore particle is represented by k, the number of ore particles with mFe content ≥ 30%, and the total number of ore particles of this size.

[0031] NMR 干式磁选 =k·β·γ·f·s-Cc-Cm-k·Cd-k·γ·Cp (4)

[0032] in,

[0033] NMR 干式磁选 —Benefits of dry magnetic separation;

[0034] Cc – Cost of a single breakage stage;

[0035] Cm—Mining cost;

[0036] Cd — Cost of dry magnetic separation of ore;

[0037] Cp—the cost of beneficiating dry magnetic separation concentrate;

[0038] f—Recovery rate of subsequent sorting operations;

[0039] s—Price of strongly magnetic iron concentrate;

[0040] k—the sand-forming rate of the crushing process, which is generally 85-95%;

[0041] During the ore crushing process, some fine ore particles with small diameters are produced. These fine ore particles cannot be processed into concentrates by normal dry magnetic separation and photoelectric sorting. Therefore, this loss needs to be considered in the simulation experiment.

[0042] Preferably, the particle size "+r3-r4" with the highest photoelectric picking benefit in S2 is obtained in the following way:

[0043] S201. Simulated photoelectric sorting tests were conducted on n1 dry magnetic separation tailings of different particle sizes to obtain the results of the simulated photoelectric sorting tests.

[0044] S202. Based on the simulated photoelectric sorting test results of S201, plot the "NMR-threshold grade" relationship curve for photoelectric sorting of each particle size, and determine the particle size "+r3-r4" corresponding to the maximum photoelectric sorting benefit.

[0045] Preferably, in S201, the simulated photoelectric sorting test is as follows: the Fe grade of each ore block in each particle size is determined, and the ore blocks are sorted in order of Fe grade from high to low; wherein a certain Fe grade is used as a threshold, the ore above this threshold is sorting concentrate, and the ore below this threshold is sorting tailings.

[0046] Preferably, in S202, different sorting thresholds are selected multiple times. Based on the results of the simulated photoelectric sorting test in S301, the mass m, yield γ, grade β, and concentrate recovery rate ε of the sorted concentrate under each sorting threshold condition are statistically analyzed, and the photoelectric sorting benefit index NMR under each threshold condition is calculated. 光电拣选 Among them, the yield γ, grade β, recovery rate ε of photoelectric sorting concentrate and the NMR (non-metallic mineral density index) of photoelectric sorting are included. 光电拣选 The calculations are shown in equations (5)-(8):

[0047]

[0048] Where γ represents the concentrate yield in the simulated photoelectric sorting test, m i The mass of the i-th ore particle is represented by , k represents the number of ore particles with a grade higher than the sorting threshold, and n represents the total number of ore particles in this size class.

[0049]

[0050] Where β represents the concentrate grade under the sorting threshold grade condition, m i x represents the mass of the i-th ore particle. i represents the grade of the i-th ore particle; k represents the number of ore particles with a grade higher than the sorting threshold.

[0051]

[0052] Where ε represents the picking recovery rate under the picking threshold grade condition, m i x represents the mass of the i-th ore particle. i represents the grade of the i-th ore particle, k represents the number of ore particles with a grade higher than the sorting threshold, and n represents the total number of ore particles of this size class.

[0053]

[0054] in,

[0055] NMR 光电拣选 —Benefits from photoelectric picking;

[0056] Cc – Cost of secondary crushing;

[0057] Cs—The photoelectric sorting cost for ore with a feed size of 50mm (baseline ore); Since the number of ore blocks increases after crushing the coarse-grained ore, the sorting cost increases. Let the sorting cost of the baseline ore be Cs, then the sorting cost of the crushed coarse-grained ore is Cs. 粗 It is directly proportional to Cs, that is, Cs 粗 =aCs, where,

[0058] r n —Actual particle size of ore selected by photoelectric sorting;

[0059] r0—the particle size of the reference ore, typically 50mm;

[0060] Cp—the cost of beneficiation of concentrate by photoelectric sorting;

[0061] Cr – Disposal cost of tailings from photoelectric sorting;

[0062] f—Recovery rate of subsequent sorting operations;

[0063] s—Price of iron concentrate;

[0064] k—the sand-forming rate of the crushing process, which is generally 85-95%;

[0065] During the ore crushing process, some fine ore particles with small particle sizes are produced. These fine ore particles cannot be processed into concentrate through normal photoelectric sorting, so this loss needs to be considered in the simulation test.

[0066] Preferably, in S202, the "NMR-threshold grade" relationship curve of photoelectric sorting for each particle size is plotted. The curve is plotted with the benefit index NMR of photoelectric sorting as the vertical axis and the threshold grade as the horizontal axis. The curves of different particle sizes of ore are plotted on the same coordinate graph. The sorting particle size and threshold grade corresponding to the highest benefit of photoelectric sorting are determined according to the highest point of the curve.

[0067] Preferably, the judgment condition "r2≥r4" in S5 is not true, leading to the conclusion that the pre-selected process requires a single-stage crushing process, specifically as follows:

[0068] S501. Take another sufficient amount of raw ore sample and screen the ore with particle size distribution in the range of "+r1-r4" into n2 different particle sizes.

[0069] S502. Simulated dry magnetic separation test was conducted on n2 ore samples of different particle sizes from S501 to obtain simulated dry magnetic separation test data.

[0070] S503. Calculate the NMR (Neural Magnetic Separation) index for dry magnetic separation of n² different particle sizes based on the simulated dry magnetic separation test data from S502. 干式磁选 ;

[0071] S504. Simulated photoelectric sorting tests were conducted on the n2 different particle sizes of dry magnetic separation tailings from S503 to obtain simulated photoelectric sorting test data.

[0072] S505. Based on the simulated photoelectric sorting test data from step S504, plot the NMR-threshold grade relationship curves for photoelectric sorting at n² different particle sizes, and find the maximum NMR benefit of photoelectric sorting at n² different particle sizes. 拣选max ;

[0073] S506, Calculate the total benefit of dry magnetic separation and photoelectric sorting for n2 different particle sizes in S505 using NMR. 总 NMR 总 The grain size corresponding to the maximum value "+r" n -r m The optimal sorting particle size was determined; and the final conclusion was that the pre-selection process using single-stage crushing resulted in an optimal crushing particle size of r. m .

[0074] Preferably, in S501, the ratio of the upper and lower limits of the particle size of the n2 different particle sizes is not greater than 1.5:1.

[0075] Preferably, in S502, the simulated dry magnetic separation test considers ore blocks with an mFe content ≥30% as dry magnetic separation concentrate; this is because when the mFe content in the ore block is ≥30%, the ore block can be attracted by the magnetic poles of the weak magnetic dry magnetic separator, causing it to separate from other ore blocks and become dry magnetic separation concentrate.

[0076] Preferably, in step S503, the mass m, yield γ, grade β, and recovery rate ε of the dry magnetic separation concentrate for each particle size are statistically analyzed, and the dry magnetic separation benefit index NMR for each particle size is calculated. 干式磁选 Dry magnetic separation concentrate yield γ, concentrate grade β, concentrate recovery ε, and NMR. 干式磁选 The calculation method is as before.

[0077] Preferably, in S504, the simulated photoelectric sorting test is as follows: the Fe grade of each ore block of each particle size is determined, and the ore blocks are sorted in order of Fe grade from high to low; wherein a certain Fe grade is used as a threshold, the ore above this threshold is sorting concentrate, and the ore below this threshold is sorting tailings.

[0078] Preferably, in S505, different sorting thresholds are selected multiple times, and the mass m, yield γ, grade β, and recovery rate ε of the sorted concentrate are statistically analyzed under each sorting threshold condition. The photoelectric sorting benefit index NMR is also calculated under each sorting threshold condition. 光电拣选 Among them, the concentrate yield γ, concentrate grade β, concentrate recovery rate ε, and revenue index NMR in the photoelectric sorting stage are... 光电拣选 The calculation method is as before; then, based on the obtained data, plot the "NMR-threshold grade" relationship curves for each particle size in the photoelectric sorting process, and determine the maximum NMR benefit for each particle size ore during photoelectric sorting based on the curves. 拣选max .

[0079] Preferably, in S506, the total benefit of dry magnetic separation and photoelectric sorting of the i-th particle size ore is NMR i总 The formula for calculation is shown below:

[0080] NMR i总 =NMR i干式磁选 +NMR i拣选max .

[0081] Preferably, NMR i总 The sorting particle size corresponding to the maximum value is "+r". n -r m "As the granularity with the greatest benefit."

[0082] Preferably, the photoelectric separation mainly separates the remaining iron minerals (mainly weakly magnetic minerals, and also contains a small amount of strongly magnetic minerals that were not separated by dry magnetic separation due to their low mFe content) from the dry magnetic separation tailings. By utilizing the different Fe grades between the ore blocks, the ore with Fe grades higher than a certain threshold is separated as sorting concentrate, and the remaining ore is used as sorting tailings.

[0083] Preferably, the photoelectric separation uses an XRF sorting device to perform photoelectric sorting on the crushed dry magnetic separation tailings by utilizing the difference in Fe grade between each ore block, to obtain weak magnetic concentrate and sorted tailings.

[0084] Preferably, if the condition "r2≥r4" in S3 is met in S4, the pre-selection process adopts two-stage crushing, and the specific pre-selection process is as follows:

[0085] S41, Primary Crushing: Crushing strong and weak magnetic mixed iron ore to the particle size r2 that maximizes the benefits of dry magnetic separation, to obtain pulverized strong and weak magnetic mixed iron ore;

[0086] S42, Dry magnetic separation: The strong magnetic iron minerals in the crushed strong and weak magnetic mixed iron ore of S41 are separated by dry magnetic separation and screened out as strong magnetic concentrate, while other minerals are sent to the next stage of screening as dry magnetic separation tailings.

[0087] S43, Secondary Crushing: The dry magnetic separation tailings of S42 are crushed to the particle size r4, which maximizes the benefits of photoelectric sorting, to obtain pulverized dry magnetic separation tailings.

[0088] S44, Photoelectric sorting: Weakly magnetic iron minerals in the crushed dry magnetic separation tailings of S43 are separated by photoelectric sorting and screened as weakly magnetic concentrate, and the remaining ore is sorting tailings.

[0089] Preferably, if the condition "r2≥r4" in S3 is not met in S5, the pre-selection process adopts a single-stage crushing process, and the specific pre-selection process is as follows:

[0090] S51, Primary Crushing: Crushing strongly and weakly magnetic mixed iron ore into particle sizes that maximize the benefits of dry magnetic separation. m To obtain pulverized iron ore with strong and weak magnetic properties;

[0091] S52, Dry magnetic separation: The strong magnetic iron minerals in the crushed strong and weak magnetic mixed iron ore of S51 are screened out by dry magnetic separation as strong magnetic concentrate, and the other minerals are sent to the next stage of screening as dry magnetic separation tailings.

[0092] S53, Photoelectric sorting: Weakly magnetic iron minerals from other minerals in S52 are screened out by photoelectric sorting as weakly magnetic concentrate, and the remaining ore is sorting tailings.

[0093] Technical objective of this invention:

[0094] On the one hand, the mineral processing revenue calculation method is used to calculate the mineral processing revenue index NMR generated by each particle size of the raw ore during dry magnetic separation and photoelectric sorting, so as to determine the optimal crushing particle size for the first and second stage crushing of the pre-selection process.

[0095] On the other hand, this process and method enable the effective separation of strong and weak magnetic iron ores, thereby maximizing the benefits of sorting.

[0096] The above technical solution has at least the following advantages compared with the existing technology:

[0097] The above-described solution provides a pre-selection process for strongly and weakly magnetic mixed iron ore, which solves the technical defects of current pre-selection methods for strongly and weakly magnetic mixed iron ore, such as complex separation device structure, high operation difficulty, high cost and low efficiency of the pre-selection process, and many inclusions in the separated minerals, thus facilitating large-scale industrial production.

[0098] This invention utilizes the synergistic application of dry magnetic separation waste disposal and photoelectric separation technology for ore particles. By adopting a pre-selection process of "dry magnetic separation + photoelectric sorting", it can fully leverage the technical characteristics of large processing capacity of dry magnetic separation and high precision of photoelectric separation, achieving complementary advantages of the two technologies. This allows for the smooth pre-selection of mixed iron ore with strong and weak magnetic properties, resulting in high separation efficiency and fewer impurities.

[0099] The present invention utilizes the synergistic method of dry magnetic separation waste disposal and photoelectric separation technology for ore particles by first performing dry magnetic separation waste disposal followed by photoelectric separation technology for ore particles. Specifically, a dry weak magnetic separator is first used to separate the strongly magnetic minerals in the raw ore in advance, thereby greatly reducing the amount of ore to be sorted by photoelectric separation. Then, photoelectric separation technology is used to recover the remaining iron minerals (mainly weak magnetic minerals, with a small amount of strongly magnetic minerals) in the tailings of dry magnetic separation. To improve the separation efficiency, in order to better obtain the concentrate from the separation of strongly and weakly magnetic mixed iron ore, two-stage crushing and particle size selection are required.

[0100] The particle size selection for the two-stage crushing process in this invention needs to be determined. This simulated dry magnetic separation test considers ore blocks with an mFe content ≥30% as dry magnetic separation concentrate. Furthermore, it requires calculation of the dry magnetic separation benefit index (NMR) for each particle size based on data such as the mass m, yield γ, grade β, and recovery rate ε of the dry magnetic separation concentrate for each particle size. 干式磁选 .

[0101] This invention defines the particle size distribution corresponding to the maximum dry magnetic separation benefit as "+r1-r2" and the particle size distribution corresponding to the maximum photoelectric sorting benefit as "+r3-r4". The condition "r2≥r4" is used to determine if it holds. If it does, particle size selection is performed using a two-stage crushing process. The optimal particle size for the first stage crushing (before dry magnetic separation) is r2, and the optimal particle size for the second stage crushing (before photoelectric sorting) is r4. If the condition does not hold, NMR is used. 总 The grain size corresponding to the maximum value "+r" n -r m "To achieve the optimal sorting particle size, this pre-selection process employs a single-stage crushing process, with the optimal crushing particle size being r." m .

[0102] In summary, compared with other traditional methods, the method of this invention first separates strong magnetic concentrate and then weak magnetic concentrate by synergistically utilizing dry magnetic separation waste disposal and photoelectric separation technology for ore particles. The separation process requires the judgment condition "r2≥r4" to determine the number of crushing stages and the corresponding particle size selection. This method is low in cost, high in efficiency, has simple influencing factors, convenient simulation calculation results, and wide applicability, which is conducive to industrial production practice and large-scale promotion. Attached Figure Description

[0103] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0104] Figure 1 This is a flowchart illustrating the method for selecting the number of crushing stages in a pre-selection process for strongly and weakly magnetic mixed iron ore, as well as the method for obtaining the particle size and particle size with the highest yield in each crushing stage according to the present invention.

[0105] Figure 2 This is a schematic diagram of the two-stage crushing process in a pre-selection process for strongly and weakly magnetic mixed iron ore according to the present invention.

[0106] Figure 3 This is a schematic diagram of a crushing process in a pre-selection process for strongly and weakly magnetic mixed iron ore according to the present invention. Detailed Implementation

[0107] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0108] To address the technical problem of this invention, a pre-selection process for iron ore with strong and weak magnetic properties is proposed. This process is a composite separation method combining dry magnetic separation and photoelectric sorting. The composite separation method needs to be coordinated with a crushing process, and the specific steps are as follows:

[0109] S1, Obtain the particle size "+r1-r2" that maximizes the benefits of dry magnetic separation;

[0110] S2, Obtain the particle size "+r3-r4" that maximizes the benefits of photoelectric picking;

[0111] S3. Determine whether the condition “r2≥r4” is true;

[0112] S4. If the condition “r2≥r4” in S3 is met, the pre-selection process adopts two-stage crushing. The optimal particle size of the first stage crushing before dry magnetic separation is r2, and the optimal particle size of the second stage crushing before photoelectric sorting is r4.

[0113] S5. If condition "r2≥r4" in S3 does not hold, the pre-selection process employs a crushing stage before dry magnetic separation. The total benefit of dry magnetic separation and photoelectric sorting is NMR. 总 NMR 总 The grain size corresponding to the maximum value "+r" n -r m The optimal sorting particle size and optimal crushing particle size is r. m .

[0114] Specifically, the particle size "+r1-r2" that yields the greatest benefit from dry magnetic separation in S1 is obtained as follows:

[0115] S101. Select a sufficient amount of raw ore sample and screen the ore into n1 different particle sizes according to the upper limit R1 and lower limit R2 of the sample particle size.

[0116] S102. Simulated dry magnetic separation test was conducted on n1 ore samples of different particle sizes from S101 to obtain the results of the simulated dry magnetic separation test.

[0117] S103. Based on the simulated dry magnetic separation test results in S102, calculate the NMR (Neural Magnetic Reduction) index for dry magnetic separation at n1 different particle sizes. 干式磁选 Determine the particle size "+r1-r2" corresponding to the maximum dry magnetic separation benefit value.

[0118] Specifically, in S101, the ratio of the upper and lower limits of the particle size of the n1 different particle sizes is no greater than 3:1.

[0119] Specifically, in S102, the simulated dry magnetic separation test considers ore blocks with an mFe content ≥30% as dry magnetic separation concentrate; this is because when the mFe content in the ore block is ≥30%, the ore block can be attracted by the magnetic poles of the weak magnetic dry magnetic separator, causing it to separate from other ore blocks and become dry magnetic separation concentrate.

[0120] Specifically, in S103, based on the simulated dry magnetic separation test results of S102, the mass m, yield γ, grade β, recovery rate ε, and other data of the dry magnetic separation concentrate for each particle size are statistically analyzed, and the dry magnetic separation benefit index NMR for each particle size is calculated. 干式磁选 Yield γ, grade β, recovery ε, and NMR of dry magnetic separation concentrates of various particle sizes. 干式磁选 The calculation formulas are shown in equations (1)-(4) respectively. When NMR 干式磁选 The particle size corresponding to the maximum value is the optimal particle size for dry magnetic separation;

[0121]

[0122] Where γ represents the concentrate yield of the simulated dry magnetic separation test, m iThe mass of the i-th ore particle is represented by k, which represents the number of ore particles with an mFe content ≥ 30%; and the total number of ore particles of this size range is represented by n.

[0123]

[0124] Where β represents the concentrate grade in the simulated dry magnetic separation test, m i x represents the mass of the i-th ore particle. i represents the grade of the i-th ore particle; k represents the number of ore particles with mFe content ≥ 30%;

[0125]

[0126] Where ε represents the recovery rate of the simulated dry magnetic separation test, m i x represents the mass of the i-th ore particle. i The grade of the i-th ore particle is represented by k, the number of ore particles with mFe content ≥ 30%, and the total number of ore particles of this size.

[0127] NMR 干式磁选 =k·β·γ·f·s-Cc-Cm-k·Cd-k·γ·Cp (4)

[0128] in,

[0129] NMR 干式磁选 —Benefits of dry magnetic separation;

[0130] Cc – Cost of a single breakage stage;

[0131] Cm—Mining cost;

[0132] Cd — Cost of dry magnetic separation of ore;

[0133] Cp—the cost of beneficiating dry magnetic separation concentrate;

[0134] f—Recovery rate of subsequent sorting operations;

[0135] s—Price of strongly magnetic iron concentrate;

[0136] k—the sand-forming rate of the crushing process, which is generally 85-95%;

[0137] During the ore crushing process, some fine ore particles with small diameters are produced. These fine ore particles cannot be processed into concentrates by normal dry magnetic separation and photoelectric sorting. Therefore, this loss needs to be considered in the simulation experiment.

[0138] Specifically, the method for obtaining the particle size "+r3-r4" that yields the greatest benefit from photoelectric picking in S2 is as follows:

[0139] S201. Simulated photoelectric sorting tests were conducted on n1 dry magnetic separation tailings of different particle sizes to obtain the results of the simulated photoelectric sorting tests.

[0140] S202. Based on the simulated photoelectric sorting test results of S201, plot the "NMR-threshold grade" relationship curve for photoelectric sorting of each particle size, and determine the particle size "+r3-r4" corresponding to the maximum photoelectric sorting benefit.

[0141] Specifically, in S201, the simulated photoelectric sorting test is as follows: the Fe grade of each ore block in each particle size is determined, and the ore blocks are sorted in order of Fe grade from high to low; a certain Fe grade is used as a threshold, and the ore above this threshold is sorted concentrate, while the ore below this threshold is sorted tailings.

[0142] Specifically, in S202, different sorting thresholds were selected multiple times. Based on the results of the simulated photoelectric sorting test in S301, the mass m, yield γ, grade β, and concentrate recovery rate ε of the sorted concentrate under each sorting threshold condition were statistically analyzed. The photoelectric sorting benefit index NMR under each threshold condition was also calculated. 光电拣选 Among them, the yield γ, grade β, recovery rate ε of photoelectric sorting concentrate and the NMR (non-metallic mineral density index) of photoelectric sorting are included. 光电拣选 The calculations are shown in equations (5)-(8):

[0143]

[0144] Where γ represents the concentrate yield in the simulated photoelectric sorting test, m i The mass of the i-th ore particle is represented by , k represents the number of ore particles with a grade higher than the sorting threshold, and n represents the total number of ore particles in this size class.

[0145]

[0146] Where β represents the concentrate grade under the sorting threshold grade condition, m i x represents the mass of the i-th ore particle. i represents the grade of the i-th ore particle; k represents the number of ore particles with a grade higher than the sorting threshold.

[0147]

[0148] Where ε represents the picking recovery rate under the picking threshold grade condition, m i x represents the mass of the i-th ore particle. i represents the grade of the i-th ore particle, k represents the number of ore particles with a grade higher than the sorting threshold, and n represents the total number of ore particles of this size class.

[0149]

[0150] in,

[0151] NMR 光电拣选 —Benefits from photoelectric picking;

[0152] Cc – Cost of secondary crushing;

[0153] Cs—The photoelectric sorting cost for ore with a feed size of 50mm (baseline ore); Since the number of ore blocks increases after crushing the coarse-grained ore, the sorting cost increases. Let the sorting cost of the baseline ore be Cs, then the sorting cost of the crushed coarse-grained ore is Cs. 粗 It is directly proportional to Cs, that is, Cs 粗 =aCs, where,

[0154] r n —Actual particle size of ore selected by photoelectric sorting;

[0155] r0—the particle size of the reference ore, typically 50mm;

[0156] Cp—the cost of beneficiation of concentrate by photoelectric sorting;

[0157] Cr – Disposal cost of tailings from photoelectric sorting;

[0158] f—Recovery rate of subsequent sorting operations;

[0159] s—Price of iron concentrate;

[0160] k—the sand-forming rate of the crushing process, which is generally 85-95%;

[0161] During the ore crushing process, some fine ore particles with small particle sizes are produced. These fine ore particles cannot be processed into concentrate through normal photoelectric sorting, so this loss needs to be considered in the simulation test.

[0162] Specifically, in S202, the "NMR-threshold grade" relationship curves for photoelectric sorting of each particle size are plotted. The curves are plotted with the NMR, the benefit index of photoelectric sorting, as the vertical axis and the threshold grade as the horizontal axis. The curves for different particle sizes of ore are plotted on the same coordinate graph. The sorting particle size and threshold grade corresponding to the highest benefit of photoelectric sorting are determined based on the highest point of the curve.

[0163] Specifically, the condition "r2≥r4" in S5 is not met, leading to the conclusion that this pre-selected process requires a single-stage crushing operation, specifically as follows:

[0164] S501. Take another sufficient amount of raw ore sample and screen the ore with particle size distribution in the range of "+r1-r4" into n2 different particle sizes.

[0165] S502. Simulated dry magnetic separation test was conducted on n2 ore samples of different particle sizes from S501 to obtain simulated dry magnetic separation test data.

[0166] S503. Calculate the NMR (Neural Magnetic Separation) index for dry magnetic separation of n² different particle sizes based on the simulated dry magnetic separation test data from S502. 干式磁选 ;

[0167] S504. Simulated photoelectric sorting tests were conducted on the n2 different particle sizes of dry magnetic separation tailings from S503 to obtain simulated photoelectric sorting test data.

[0168] S505. Based on the simulated photoelectric sorting test data from step S504, plot the NMR-threshold grade relationship curves for photoelectric sorting at n² different particle sizes, and find the maximum NMR benefit of photoelectric sorting at n² different particle sizes. 拣选max ;

[0169] S506, Calculate the total benefit of dry magnetic separation and photoelectric sorting for n2 different particle sizes in S505 using NMR. 总 NMR 总 The grain size corresponding to the maximum value "+r" n -r m The optimal sorting particle size was determined; and the final conclusion was that the pre-selection process using single-stage crushing resulted in an optimal crushing particle size of r. m .

[0170] Specifically, in S501, the ratio of the upper and lower limits of the particle size of n2 different particle sizes is no greater than 1.5:1.

[0171] Specifically, in S502, the simulated dry magnetic separation test considers ore blocks with an mFe content ≥30% as dry magnetic separation concentrate; this is because when the mFe content in the ore block is ≥30%, the ore block can be attracted by the magnetic poles of the weak magnetic dry magnetic separator, causing it to separate from other ore blocks and become dry magnetic separation concentrate.

[0172] Specifically, in S503, data such as mass m, yield γ, grade β, and recovery rate ε of dry magnetic separation concentrate for each particle size are statistically analyzed, and the dry magnetic separation benefit index NMR for each particle size is calculated. 干式磁选 Dry magnetic separation concentrate yield γ, concentrate grade β, concentrate recovery ε, and NMR. 干式磁选 The calculation method is as before.

[0173] Specifically, in S504, the simulated photoelectric sorting test is as follows: the Fe grade of each ore block in each particle size is determined, and the ore blocks are sorted in order of Fe grade from high to low; a certain Fe grade is used as a threshold, and the ore above this threshold is sorted concentrate, while the ore below this threshold is sorted tailings.

[0174] Specifically, in S505, different sorting thresholds were selected multiple times, and the mass m, yield γ, grade β, and recovery rate ε of the sorted concentrate were statistically analyzed under each sorting threshold condition. The photoelectric sorting benefit index NMR was also calculated under each sorting threshold condition. 光电拣选 Among them, the concentrate yield γ, concentrate grade β, concentrate recovery rate ε, and revenue index NMR in the photoelectric sorting stage are... 光电拣选 The calculation method is as before; then, based on the obtained data, plot the "NMR-threshold grade" relationship curves for each particle size in the photoelectric sorting process, and determine the maximum NMR benefit for each particle size ore during photoelectric sorting based on the curves. 拣选max .

[0175] Specifically, in S506, the total benefit of dry magnetic separation and photoelectric sorting of the i-th particle size ore is NMR. i总 The formula for calculation is shown below:

[0176] NMR i总 =NMR i干式磁选 +NMR i拣选max .

[0177] Specifically, NMR i总 The sorting particle size corresponding to the maximum value is "+r". n -r m "As the granularity with the greatest benefit."

[0178] Specifically, the photoelectric separation mainly separates the remaining iron minerals (mainly weakly magnetic minerals, and also contains a small amount of strongly magnetic minerals that were not separated by dry magnetic separation due to their low mFe content) from the dry magnetic separation tailings. By utilizing the different Fe grades between the ore blocks, the ore with Fe grades higher than a certain threshold is separated as sorting concentrate, and the remaining ore is used as sorting tailings.

[0179] Specifically, the photoelectric separation uses XRF sorting equipment to perform photoelectric sorting on the dry magnetic separation tailings after crushing by utilizing the difference in Fe grade between each ore block, to obtain weak magnetic concentrate and sorted tailings.

[0180] Specifically, if condition "r2≥r4" in S3 is true in S4, the pre-selected process adopts two-stage crushing, and the specific pre-selected process is as follows:

[0181] S41, Primary Crushing: Crushing strong and weak magnetic mixed iron ore to the particle size r2 that maximizes the benefits of dry magnetic separation, to obtain pulverized strong and weak magnetic mixed iron ore;

[0182] S42, Dry magnetic separation: The strong magnetic iron minerals in the crushed strong and weak magnetic mixed iron ore of S41 are separated by dry magnetic separation and screened out as strong magnetic concentrate, while other minerals are sent to the next stage of screening as dry magnetic separation tailings.

[0183] S43, Secondary Crushing: The dry magnetic separation tailings of S42 are crushed to the particle size r4, which maximizes the benefits of photoelectric sorting, to obtain pulverized dry magnetic separation tailings.

[0184] S44, Photoelectric sorting: Weakly magnetic iron minerals in the crushed dry magnetic separation tailings of S43 are separated by photoelectric sorting and screened as weakly magnetic concentrate, and the remaining ore is sorting tailings.

[0185] Specifically, if the condition "r2≥r4" in S3 does not hold in S5, the pre-selected process adopts a single-stage crushing process, as follows:

[0186] S51, Primary Crushing: Crushing strongly and weakly magnetic mixed iron ore into particle sizes that maximize the benefits of dry magnetic separation. m To obtain pulverized iron ore with strong and weak magnetic properties;

[0187] S52, Dry magnetic separation: The strong magnetic iron minerals in the crushed strong and weak magnetic mixed iron ore of S51 are screened out by dry magnetic separation as strong magnetic concentrate, and the other minerals are sent to the next stage of screening as dry magnetic separation tailings.

[0188] S53, Photoelectric sorting: Weakly magnetic iron minerals from other minerals in S52 are screened out by photoelectric sorting as weakly magnetic concentrate, and the remaining ore is sorting tailings.

[0189] Example 1

[0190] A pre-selection process for iron ore with strong and weak magnetic mixing is disclosed. This process is a composite separation method combining dry magnetic separation and photoelectric sorting. The composite separation method needs to be coordinated with crushing. In this embodiment, the test subject is the raw ore from an iron ore beneficiation plant, with a particle size range of 4.3-100 mm. Specifically, in conjunction with… Figure 1 The following steps are required:

[0191] S1. Obtain the particle size "+r1-r2" that yields the greatest benefit from dry magnetic separation. The specific method for obtaining this is as follows:

[0192] S101. Select a representative ore sample of 200 kg and sieve it into five different particle sizes: +4.3-10.75 mm, +10.75-21.5 mm, +21.5-43.0 mm, +43.0-64.5 mm, and +64.5-100 mm, based on the upper limit of the particle size of 100 mm and the lower limit of the particle size of 4.3 mm. Randomly select 200 ore particles from each particle size, number and weigh each individual ore particle, grind the weighed ore particles to below 0.074 mm, measure the mFe grade of each ore particle, and sort the numbered ores in descending order of grade.

[0193] S102. Simulated dry magnetic separation tests were conducted on 5 different particle size ore samples from S101. Among them, ore with mFe grade ≥30% was used as dry magnetic separation concentrate product to obtain the results of simulated dry magnetic separation test.

[0194] S103. Based on the simulated dry magnetic separation test results in S102, calculate the NMR (Neural Magnetic Reduction) index for dry magnetic separation at five different particle sizes. 干式磁选 Determine the particle size "+r1-r2" corresponding to the maximum dry magnetic separation benefit value;

[0195] The process involves calculating the yield, grade, and recovery rate of dry magnetic separation concentrates for five different particle sizes. The remaining ore particles are then treated as dry magnetic separation tailings and proceeded to the next sorting step. Furthermore, the Fe grade of each particle size dry magnetic separation tailings is determined and sorted in descending order of grade. The yield, grade, and recovery rate of the sorted concentrate under different threshold grade conditions are then calculated.

[0196] Conclusion: Calculations show that the maximum dry magnetic separation benefit corresponds to a particle size range of +21.5-43.0 mm.

[0197] S2. Obtain the particle size "+r3-r4" that maximizes photoelectric picking benefits. The specific method for obtaining this is as follows:

[0198] S201. Simulated photoelectric sorting tests were conducted on dry magnetic separation tailings of five different particle sizes to obtain the results of the simulated photoelectric sorting tests.

[0199] S202. Based on the simulated photoelectric sorting test results of S201, plot the "NMR-threshold grade" relationship curve for photoelectric sorting of each particle size, and determine the particle size "+r3-r4" corresponding to the maximum photoelectric sorting benefit.

[0200] Conclusion: Calculations show that the optimal particle size for photoelectric picking is +10.75-21.5mm;

[0201] According to the investigation: In this embodiment, the crushing cost of a certain iron ore beneficiation plant is RMB 15.80 / t, the dry magnetic separation cost is RMB 23.50 / t, the dry magnetic separation concentrate beneficiation cost is RMB 64.30 / t, the photoelectric sorting cost of the benchmark ore is RMB 12.00 / t, the photoelectric sorting concentrate beneficiation cost is RMB 69.75 / t, the photoelectric sorting tailings disposal cost is RMB 0 / t, the recovery rate of subsequent beneficiation operations is 92.00%, the mining cost is RMB 39.17 / t, the iron concentrate price is RMB 1160 / t, and the crushing to sand rate is 90%. The maximum separation revenue of dry magnetic separation and photoelectric sorting of different particle size ores is calculated according to formulas (1)-(8).

[0202] The experimental data obtained are shown in Table 1 below:

[0203] Table 1

[0204]

[0205] S3. Determine whether the condition “r2≥r4” is true;

[0206] S4. As can be seen from the above, the condition "r2≥r4" in S3 is true. The optimal separation particle size of dry magnetic separation is greater than that of photoelectric sorting. Therefore, it is determined that the pre-selection process should adopt two-stage crushing, that is, the crushing particle size of the first stage crushing (before dry magnetic separation) is 43.0mm, and the crushing particle size of the second stage crushing (before photoelectric sorting) is 21.5mm.

[0207] Specific pre-selected processes are as follows: Figure 2 As shown:

[0208] S41, Primary crushing: The strong and weak magnetic mixed iron ore is crushed to the particle size of 43.0mm, which maximizes the benefits of dry magnetic separation, and then screened to obtain pulverized strong and weak magnetic mixed iron ore and fine ore.

[0209] S42, Dry magnetic separation: The strong magnetic iron minerals in the crushed strong and weak magnetic mixed iron ore of S41 are separated by dry magnetic separation and screened out as strong magnetic concentrate and other minerals. The other minerals are used as dry magnetic separation tailings and enter the next stage of screening.

[0210] S43, Secondary Crushing: The dry magnetic separation tailings of S42 are crushed to a particle size of 21.5mm, which maximizes the benefits of photoelectric sorting. After screening, crushed dry magnetic separation tailings and fine ore are obtained.

[0211] S44, Photoelectric sorting: Weakly magnetic iron minerals in the crushed dry magnetic separation tailings of S43 are screened out by photoelectric sorting as weakly magnetic concentrate. The threshold grade for photoelectric sorting is 23.17%, and the remaining ore is tailings.

[0212] In this embodiment, after the raw ore is separated by the pre-selection process, the yield of strong magnetic concentrate by dry magnetic separation is 60.33% and the mFe grade is 43.77%, with a dry magnetic separation profit of 142.61 yuan / t; the yield of weak magnetic concentrate by photoelectric sorting is 48.28% and the concentrate Fe grade is 33.23%, with a photoelectric sorting profit of 74.50 yuan / t.

[0213] Example 2

[0214] A pre-selection process for iron ore with strong and weak magnetic mixing is disclosed. This process is a composite separation method combining dry magnetic separation and photoelectric sorting. The composite separation method requires coordination with crushing. In this embodiment, the test subject is the raw ore from an iron ore beneficiation plant, with a particle size range of 6.7-150 mm. Specifically, in conjunction with… Figure 1 The following steps are required:

[0215] S1. Obtain the particle size "+r1-r2" that yields the greatest benefit from dry magnetic separation. The specific method for obtaining this is as follows:

[0216] S101. Select a representative ore sample of 200 kg and sieve it into five different particle sizes: +6.7-13.4 mm, +13.4-26.8 mm, +26.8-53.6 mm, +53.6-107.2 mm, and +107.2-150 mm, based on the upper limit of the particle size of 150 mm and the lower limit of the particle size of 6.7 mm. Randomly select 200 ore particles from each particle size, number and weigh each individual ore particle, grind the weighed ore particles to below 0.074 mm, measure the mFe grade of each ore particle, and sort the numbered ores in descending order of grade.

[0217] S102. Simulated dry magnetic separation tests were conducted on 5 different particle size ore samples from S101. Among them, ore with mFe grade ≥30% was used as dry magnetic separation concentrate product to obtain the results of simulated dry magnetic separation test.

[0218] S103. Based on the simulated dry magnetic separation test results in S102, calculate the NMR (Neural Magnetic Reduction) index for dry magnetic separation at five different particle sizes. 干式磁选 Determine the particle size "+r1-r2" corresponding to the maximum dry magnetic separation benefit value;

[0219] The process involves calculating the yield, grade, and recovery rate of dry magnetic separation concentrates for five different particle sizes. The remaining ore particles are then treated as dry magnetic separation tailings and proceeded to the next sorting step. Furthermore, the Fe grade of each particle size dry magnetic separation tailings is determined and sorted in descending order of grade. The yield, grade, and recovery rate of the sorted concentrate under different threshold grade conditions are then calculated.

[0220] Conclusion: Calculations show that the maximum dry magnetic separation benefit corresponds to a particle size range of +13.4-26.8 mm.

[0221] S2. Obtain the particle size "+r3-r4" that maximizes photoelectric picking benefits. The specific method for obtaining this is as follows:

[0222] S201. Simulated photoelectric sorting tests were conducted on dry magnetic separation tailings of five different particle sizes to obtain the results of the simulated photoelectric sorting tests.

[0223] S202. Based on the simulated photoelectric sorting test results of S201, plot the "NMR-threshold grade" relationship curve for photoelectric sorting of each particle size, and determine the particle size "+r3-r4" corresponding to the maximum photoelectric sorting benefit.

[0224] Conclusion: Calculations show that the optimal particle size for photoelectric sorting is +26.8-53.6 mm.

[0225] According to the investigation: In this embodiment, the crushing cost of a certain iron ore beneficiation plant is RMB 15.80 / t, the dry magnetic separation cost is RMB 23.50 / t, the dry magnetic separation concentrate beneficiation cost is RMB 64.30 / t, the photoelectric sorting cost of the benchmark ore is RMB 12.00 / t, the photoelectric sorting concentrate beneficiation cost is RMB 70.45 / t, the photoelectric sorting tailings disposal cost is RMB 0 / t, the recovery rate of subsequent beneficiation operations is 89.00%, the mining cost is RMB 39.17 / t, the iron concentrate price is RMB 1160 / t, and the crushing to sand rate is 91%. The maximum separation revenue of dry magnetic separation and photoelectric sorting of different particle size ores is calculated according to formulas (1)-(8).

[0226] The experimental data obtained are shown in Table 2 below:

[0227] Table 2

[0228]

[0229] S3. Determine whether the condition “r2≥r4” is true;

[0230] S5. As can be seen from the above, the condition "r2≥r4" in S3 does not hold. This pre-selection process uses a crushing stage before dry magnetic separation, and further experiments are needed to determine the optimal crushing particle size.

[0231] The specific method for determining the optimal crushing particle size in a single-stage crushing process is as follows:

[0232] S501. Take another sufficient amount of raw ore sample, and screen the ore with a particle size distribution in the range of "+13.4-53.6mm" into four different particle sizes: +13.4-20.1mm, +20.1-30.15mm, +30.15-45.25mm, and +40.25-53.6mm. Then, number and weigh the ore blocks of the four different particle sizes again.

[0233] S502. The numbered and weighed ore blocks of four different particle sizes from S501 were subjected to simulated dry magnetic separation tests to obtain simulated dry magnetic separation test data.

[0234] S503. Based on the simulated dry magnetic separation test data from S502, calculate the NMR (Neural Magnetic Reduction) index for dry magnetic separation at four different particle sizes. 干式磁选 ;

[0235] S504. Simulated photoelectric sorting tests were conducted on the four different particle sizes of dry magnetic separation tailings from S503 to obtain simulated photoelectric sorting test data.

[0236] S505. Based on the simulated photoelectric sorting test data from step S504, plot the NMR-threshold grade relationship curves for photoelectric sorting at four different particle sizes, and find the maximum NMR benefit of photoelectric sorting at the four different particle sizes. 拣选max ;

[0237] S506, Calculate the total benefit of dry magnetic separation and photoelectric sorting for n2 different particle sizes in S505 using NMR. 总 NMR 总 The grain size corresponding to the maximum value "+r" n -r m "For optimal sorting particle size, NMR..." 总 =NMR 干式磁选 +NMR 拣选max The final conclusion is that the pre-selected process uses a single-stage crushing stage, and the optimal crushing particle size is r. m ;

[0238] Among them, the total revenue from dry magnetic separation and photoelectric sorting of the i-th particle size ore is NMR i总 The formula for calculation is shown below:

[0239] NMR i总 =NMR i干式磁选 +NMR i拣选max ;

[0240] Total benefits of dry magnetic separation and photoelectric sorting NMR 总 NMR 总 The grain size corresponding to the maximum value "+r" n -r m The optimal sorting particle size and optimal crushing particle size is r. m .

[0241] The pre-selection process uses a single-stage crushing stage; the specific pre-selection process is as follows: Figure 3 As shown:

[0242] S51, Primary crushing: The strong and weak magnetic mixed iron ore is crushed to the particle size with the greatest benefit from dry magnetic separation +20.1-30.15mm. Therefore, the crushing particle size is 30.15mm, and the crushed strong and weak magnetic mixed iron ore is obtained.

[0243] S52, Dry magnetic separation: The strong magnetic iron minerals in the crushed strong and weak magnetic mixed iron ore of S51 are screened out by dry magnetic separation as strong magnetic concentrate, and the other minerals are sent to the next stage of screening as dry magnetic separation tailings.

[0244] S53, Photoelectric Sorting: Weakly magnetic iron minerals from other minerals in S52 are screened out by photoelectric sorting as weakly magnetic concentrate. The photoelectric sorting threshold is set at 28.13%, and the remaining ore is sorting tailings.

[0245] In this embodiment, after the raw ore from the concentrator is separated by this pre-selection process, the yield of strong magnetite concentrate by dry magnetic separation is 62.07% and the mFe grade is 45.37%, generating a dry magnetic separation revenue of RMB 151.90 / t; the yield of weak magnetite concentrate by photoelectric sorting is 43.09% and the Fe grade is 35.06%, generating a photoelectric sorting revenue of RMB 76.78 / t. The total revenue generated by the entire pre-selection process is RMB 228.67 / t.

[0246] The above-described solution provides a pre-selection process for strongly and weakly magnetic mixed iron ore, which solves the technical defects of current pre-selection methods for strongly and weakly magnetic mixed iron ore, such as complex separation device structure, high operation difficulty, high cost and low efficiency of the pre-selection process, and many inclusions in the separated minerals, thus facilitating large-scale industrial production.

[0247] This invention utilizes the synergistic application of dry magnetic separation waste disposal and photoelectric separation technology for ore particles. By adopting a pre-selection process of "dry magnetic separation + photoelectric sorting", it can fully leverage the technical characteristics of large processing capacity of dry magnetic separation and high precision of photoelectric separation, achieving complementary advantages of the two technologies. This allows for the smooth pre-selection of mixed iron ore with strong and weak magnetic properties, resulting in high separation efficiency and fewer impurities.

[0248] The present invention utilizes the synergistic method of dry magnetic separation waste disposal and photoelectric separation technology for ore particles by first performing dry magnetic separation waste disposal followed by photoelectric separation technology for ore particles. Specifically, a dry weak magnetic separator is first used to separate the strongly magnetic minerals in the raw ore in advance, thereby greatly reducing the amount of ore to be sorted by photoelectric separation. Then, photoelectric separation technology is used to recover the remaining iron minerals (mainly weak magnetic minerals, with a small amount of strongly magnetic minerals) in the tailings of dry magnetic separation. To improve the separation efficiency, in order to better obtain the concentrate from the separation of strongly and weakly magnetic mixed iron ore, two-stage crushing and particle size selection are required.

[0249] The particle size selection for the two-stage crushing process in this invention needs to be determined. This simulated dry magnetic separation test considers ore blocks with an mFe content ≥30% as dry magnetic separation concentrate. Furthermore, it requires calculation of the dry magnetic separation benefit index (NMR) for each particle size based on data such as the mass m, yield γ, grade β, and recovery rate ε of the dry magnetic separation concentrate for each particle size. 干式磁选 .

[0250] This invention defines the particle size distribution corresponding to the maximum dry magnetic separation benefit as "+r1-r2" and the particle size distribution corresponding to the maximum photoelectric sorting benefit as "+r3-r4". The condition "r2≥r4" is used to determine if it holds. If it does, particle size selection is performed using a two-stage crushing process. The optimal particle size for the first stage crushing (before dry magnetic separation) is r2, and the optimal particle size for the second stage crushing (before photoelectric sorting) is r4. If the condition does not hold, NMR is used. 总 The grain size corresponding to the maximum value "+r"n -r m "To achieve the optimal sorting particle size, this pre-selection process employs a single-stage crushing process, with the optimal crushing particle size being r." m .

[0251] In summary, compared with other traditional methods, the method of this invention first separates strong magnetic concentrate and then weak magnetic concentrate by synergistically utilizing dry magnetic separation waste disposal and photoelectric separation technology for ore particles. The separation process requires the judgment condition "r2≥r4" to determine the number of crushing stages and the corresponding particle size selection. This method is low in cost, high in efficiency, has simple influencing factors, convenient simulation calculation results, and wide applicability, which is conducive to industrial production practice and large-scale promotion.

[0252] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A pre-selection process for iron ore with strong and weak magnetic properties, characterized in that, The pre-selection process for mixed strong and weak magnetic iron ore is a composite separation method combining dry magnetic separation and photoelectric sorting. This composite separation method needs to be coordinated with crushing, and the specific steps are as follows: S1, Obtain the particle size "+r1-r2" that maximizes the benefits of dry magnetic separation; S2, Obtain the particle size "+r3-r4" that maximizes the benefits of photoelectric picking; S3. Determine whether the condition "r2≥r4" is true; S4. If the condition "r2≥r4" in S3 is met, the pre-selection process adopts two-stage crushing. The optimal particle size of the first stage crushing before dry magnetic separation is r2, and the optimal particle size of the second stage crushing before photoelectric sorting is r4. S5. If condition "r2≥r4" in S3 is not met, the pre-selection process uses a crushing stage before dry magnetic separation. The total benefit of dry magnetic separation and photoelectric sorting is NMR. 总 NMR 总 The grain size corresponding to the maximum value is "+r n -r m The optimal sorting particle size and optimal crushing particle size are r. m ; The method for obtaining the particle size "+r1-r2" that yields the greatest benefit from dry magnetic separation in S1 is as follows: S101. Select a sufficient amount of raw ore sample and screen the ore into n1 different particle sizes according to the upper limit R1 and lower limit R2 of the sample particle size. S102. Simulated dry magnetic separation test was conducted on n1 ore samples of different particle sizes from S101 to obtain the results of the simulated dry magnetic separation test. S103. Based on the simulated dry magnetic separation test results in S102, calculate the NMR (Neural Magnetic Reduction) index for dry magnetic separation of n1 different particle sizes. 干式磁选 Determine the particle size "+r1-r2" corresponding to the maximum dry magnetic separation benefit value; The method for obtaining the particle size "+r3-r4" that maximizes photoelectric picking benefits in S2 is as follows: S201. Simulated photoelectric sorting tests were conducted on n1 dry magnetic separation tailings of different particle sizes to obtain the results of the simulated photoelectric sorting tests. S202. Based on the simulated photoelectric sorting test results of S201, plot the "NMR-threshold grade" relationship curve for photoelectric sorting of each particle size, and determine the particle size "+r3-r4" corresponding to the maximum photoelectric sorting benefit.

2. The pre-selection process for strongly and weakly magnetic mixed iron ore according to claim 1, characterized in that, In S101, the ratio of the upper and lower limits of the particle size of n1 different particle sizes is no greater than 3:

1.

3. The pre-selection process for strongly and weakly magnetic mixed iron ore according to claim 1, characterized in that, In S102, the simulated dry magnetic separation test considers ore blocks with mFe content ≥30% as dry magnetic separation concentrate.

4. The pre-selection process for strongly and weakly magnetic mixed iron ore according to claim 1, characterized in that, The condition "r2≥r4" in S5 is not met, leading to the conclusion that this pre-selected process requires a single-stage crushing process, as follows: S501. Take another sufficient amount of raw ore sample and screen the ore with particle size distribution in the range of "+r1-r4" into n2 different particle sizes. S502. Simulated dry magnetic separation test was conducted on n2 ore samples of different particle sizes from S501 to obtain simulated dry magnetic separation test data. S503. Calculate the NMR (Neural Magnetic Separation) index for dry magnetic separation of n² different particle sizes based on the simulated dry magnetic separation test data from S502. 干式磁选 ; S504. Simulated photoelectric sorting tests were conducted on the n2 different particle sizes of dry magnetic separation tailings from S503 to obtain simulated photoelectric sorting test data. S505. Based on the simulated photoelectric sorting test data from step S504, plot the NMR-threshold grade relationship curves for photoelectric sorting at n² different particle sizes, and find the maximum benefit of photoelectric sorting at n² different particle sizes. ; S506, Calculate the total benefit of dry magnetic separation and photoelectric sorting for n2 different particle sizes in S505 using NMR. 总 NMR 总 The grain size corresponding to the maximum value is "+r n -r m The optimal sorting particle size was determined; and the final conclusion was that the pre-selection process using single-stage crushing resulted in an optimal crushing particle size of r. m .

5. The pre-selection process for strongly and weakly magnetic mixed iron ore according to claim 4, characterized in that, In S501, the ratio of the upper and lower limits of the particle size of n2 different particle sizes is no greater than 1.5:

1.

6. The pre-selection process for strongly and weakly magnetic mixed iron ore according to claim 4, characterized in that, In S506, the total revenue from dry magnetic separation and photoelectric sorting of the i-th particle size ore is... The calculation method is shown in the formula below: 。 7. The pre-selection process for strongly and weakly magnetic mixed iron ore according to claim 4, characterized in that, If condition "r2≥r4" in S3 is true in S4, the pre-selected process adopts two-stage crushing, and the specific pre-selected process is as follows: S41, Primary Crushing: Crushing strong and weak magnetic mixed iron ore to the particle size r2 that maximizes the benefits of dry magnetic separation, to obtain pulverized strong and weak magnetic mixed iron ore; S42, Dry magnetic separation: The strong magnetic iron minerals in the crushed strong and weak magnetic mixed iron ore of S41 are screened out by dry magnetic separation as strong magnetic concentrate, and the other minerals are sent to the next stage of screening as dry magnetic separation tailings. S43, Secondary Crushing: The dry magnetic separation tailings of S42 are crushed to the particle size r4, which maximizes the benefit of photoelectric sorting, to obtain pulverized dry magnetic separation tailings. S44, Photoelectric sorting: Weakly magnetic iron minerals in the crushed dry magnetic separation tailings of S43 are separated by photoelectric sorting and screened as weakly magnetic concentrate, and the remaining ore is sorting tailings.

8. The pre-selection process for strongly and weakly magnetic mixed iron ore according to claim 4, characterized in that, If the condition "r2≥r4" in S3 is not met in S5, the pre-selected process adopts a single-stage crushing process, and the specific pre-selected process is as follows: S51, Primary Crushing: Crushing strongly and weakly magnetic mixed iron ore into particle sizes that maximize the benefits of dry magnetic separation. m To obtain pulverized iron ore with strong and weak magnetic properties; S52, Dry magnetic separation: The strong magnetic iron minerals in the crushed strong and weak magnetic mixed iron ore of S51 are screened out by dry magnetic separation as strong magnetic concentrate, and the other minerals are sent to the next stage of screening as dry magnetic separation tailings. S53, Photoelectric sorting: Weakly magnetic iron minerals in other minerals in S52 are separated by photoelectric sorting and screened out as weakly magnetic concentrate, and the remaining ore is sorting tailings.

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