Coarse fraction pre-refining process for weakly magnetic refractory iron ore

Abstract

The invention provides a weak magnetic refractory iron ore coarse fraction pre-refining process which comprises the following steps: according to different characteristics of weak magnetic iron ores with the fractions of 0-3mm, 3-15mm and 15-50mm, respectively adopting different refining processes for treatment; wherein the weakly magnetic iron ore with the particle size of 0-3 mm is subjected to wet type coarse particle size pre-refining by adopting a strong magnetic machine with the field intensity of 600 mT, and the refining grade reaches 47% or above; the weakly magnetic iron ore with the size fraction of 3-15 mm is refined through a 6000 GS high-intensity magnetic separator, and the refined grade reaches 46% or above; the weak magnetic iron ore with the size fraction of 15-50 mm is refined by adopting X-ray intelligent separation equipment, and the refined grade reaches 45% or above; the method comprises the following steps: crushing and finely grinding the extracted coarse fraction concentrates with the particle fractions of 0-3mm, 3-15mm and 15-50mm to 70% of-200 meshes, and desliming to obtain the non-magnetite concentrate with the grade of 49.5% or above and the burning loss of 19%, thereby realizing the effective utilization of the weakly magnetic refractory iron ore.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology and relates to a pre-refining process for coarse-grained weakly magnetic and difficult-to-process iron ore. Background Technology

[0002] Currently, weakly magnetic, difficult-to-process iron ore accounts for over 70% of the total reserves, with proven reserves exceeding one billion tons. High-grade iron ore reaches over 48%, while low-grade ore has a grade of around 18%. After mining, the ore from each body is crushed to below 100mm and mixed together for output, with an average grade of around 32%. This mixture then enters the beneficiation plant for screening into 0-15mm and 15-100mm sections. Some 0-15mm fines are processed using strong magnetic separation, achieving an iron concentrate grade of only around 43% and a metal recovery rate of around 65%. Other 0-15mm fines are processed using a suspension furnace magnetic roasting and weak magnetic separation process, achieving an iron concentrate grade of over 56% and a metal recovery rate of 89%. The 15-100mm section... The m-block ore is processed using a vertical shaft furnace magnetic roasting, weak magnetic separation, and reverse flotation process to achieve an iron concentrate grade of approximately 59% and a metal recovery rate of approximately 72%. However, because a certain output ore contains approximately 25% high-grade iron ore that has not undergone pre-refining, this portion of the iron ore also needs to undergo strong magnetic separation or roasting weak magnetic separation and reverse flotation. The above ore processing has drawbacks such as increased beneficiation costs and metal loss. After fine grinding of the high-grade iron ore, the tailings grade is as high as approximately 30%, regardless of whether strong or weak magnetic separation is used. Therefore, it is necessary to propose a low-cost pre-refining process technology that guarantees the lump ore yield, further reducing the beneficiation cost of weakly magnetic and difficult-to-process iron ore and achieving effective recovery and utilization of low-grade weakly magnetic and difficult-to-process iron ore. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the prior art by providing a pre-refining process for coarse-grained weakly magnetic and difficult-to-process iron ore, which solves the problems of high-grade iron ore entering the beneficiation process together with low-grade iron ore, increasing beneficiation costs and causing metal loss.

[0004] Therefore, the present invention adopts the following technical solution: A pre-refining process for coarse-grained weakly magnetic and difficult-to-process iron ore includes the following steps: Weakly magnetic and difficult-to-select iron ore with an iron content of 32% and a particle size of less than 100mm is crushed to less than 50mm using a hammer crusher and screened into three particle sizes: 0-3mm (12%), 3-15mm (38%), and 15-50mm (50%), so that the iron minerals and intergrown gangue can be fully liberated.

[0005] To effectively reduce the throughput of strong magnetic separation, roasting weak magnetic separation, and reverse flotation, and further reduce the energy consumption and carbon emission intensity of weak magnetic iron ore beneficiation, it is necessary to pre-clean in the coarse-grained state, taking into account the mixed high and low grade characteristics of weak magnetic iron ore, to minimize the amount of roasted ore and thus further reduce beneficiation costs. Weak magnetic refractory iron ore contains approximately 30% iron ore with a grade of 45% or higher, mixed with other low-grade iron ores. Since the roasting weak magnetic separation and reverse flotation indices for lump ore are better than those for strong magnetic separation, crushing and screening for particle size classification are necessary to ensure the lump ore rate. The ore should be screened into three particle sizes: 0-3mm (12%), 3-15mm (38%), and 15-50mm (50%), creating conditions for different refining processes based on particle size.

[0006] The weakly magnetic iron ore with an iron content of 32% and a particle size of less than 100mm refers to a difficult-to-process weakly magnetic iron ore that is a mixture of high and low grade ores and has unevenly distributed iron mineral particles.

[0007] Based on the different characteristics of weakly magnetic iron ore with particle sizes of 0-3mm, 3-15mm, and 15-50mm, different refining processes are adopted for processing; among which: For weakly magnetic iron ore with a particle size of 0-3mm, a wet coarse-grained pre-purification process using a 600mT high-intensity magnetic separator is employed, achieving a purity of over 47%. Specifically, 0-3mm fine ore contains approximately 6% moisture, making dry purification unsuitable. Instead, a vertical ring high-gradient magnetic separator is used for wet purification, achieving a purity of over 47% with a field strength of 600mT.

[0008] Weakly magnetic iron ore with a particle size of 3-15mm is purified using a 6000GS high-intensity magnetic separator, achieving a purity of over 46%. Small-particle-size lump ore with a particle size of 3-15mm is suitable for dry purification using a permanent magnet high-intensity magnetic separator, achieving a purity of over 46% with an field strength of 700mT.

[0009] X-ray intelligent sorting equipment is used to refine 15-50mm weakly magnetic iron ore, achieving a refined grade of over 45%. Specifically, if a strong magnetic separator is used for refining 15-50mm lump ore, the inertial force of the conveyor belt exceeds the magnetic attraction, causing the ore to be ejected as low-grade ore. Therefore, X-ray intelligent sorting equipment is more suitable. Since X-ray intelligent sorting equipment is designed for separating lumpy materials, it is particularly suitable for refining and discarding weakly magnetic iron ore. The material is identified using X-rays. AI algorithms identify and establish databases of ores, gangue, and surrounding rocks of different grades. During operation, lumpy materials are laid in a single layer on a conveyor belt traveling at a speed of 2-3 m / s. When passing through the X-ray detection area, X-rays quickly transmit and identify each mineral, transmitting the information of the material to be injected to the injection actuator to change its trajectory, thereby achieving refining or waste disposal. For 15-50mm lumpy ores, refining is performed, and iron ore with a grade of over 45% is discarded, achieving a refined grade of over 45%.

[0010] It should be noted that the X-ray intelligent sorting equipment used in this invention is an existing device, and its working principle, circuit connection method, etc. are all existing technologies, so they will not be described in detail here.

[0011] The coarse-grained concentrates of 0-3mm, 3-15mm, and 15-50mm particle sizes are crushed, finely ground to -200 mesh (70%), and deslimed to obtain a non-magnetic concentrate with a grade of over 46% and a loss on ignition of 19%, thus achieving effective utilization of weakly magnetic and difficult-to-process iron ore. Specifically, since the grade of the three particle size fractions of the concentrate has reached over 46%, and the weakly magnetic ore contains siderite and limonite with a loss on ignition of 19%, the concentrate grade after deducting the loss on ignition is over 56%. To prevent further metal loss from using strong magnetic separation to increase the concentrate grade, the concentrate is ground to -200 mesh (70%) and deslimed using a desliming tank. The desliming grade is controlled below 5%, with a desliming rate of 8%. The final concentrate grade reaches 49.56%, and the grade after deducting the loss on ignition is 61.2%.

[0012] The beneficial effects of this invention are as follows: 1. This invention is designed for crushing and screening weakly magnetic and difficult-to-separate iron ore of 0-100mm, and uses different processes for refining in different particle sizes. It fully leverages the advantages of strong magnetic separation in processing small-sized ore of 0-3mm and 3-15mm, and the advantages of intelligent sorting equipment in processing large-sized ore of 15-50mm. 2. This invention pre-processes refractory iron ore by fractionalizing it, thereby reducing the amount of ore to be processed and lowering the beneficiation cost of weakly magnetic refractory iron ore. 3. This invention obtains high-grade non-magnetic concentrate by pre-extracting coarse-grained qualified ore and performing desliming treatment, thus avoiding the problem of secondary dilution after subsequent fine grinding and realizing the effective recovery and utilization of low-grade weakly magnetic and difficult-to-select iron ore. Attached Figure Description

[0013] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0014] The technical solution of the present invention will be described below with reference to the accompanying drawings and implementation methods.

[0015] Example 1 like Figure 1 As shown, a pre-refining process for coarse-grained weakly magnetic and difficult-to-process iron ore includes the following steps: For weakly magnetic iron ore with an iron content of 32% and a particle size of less than 100mm, a hammer crusher is used to crush it to less than 50mm and screen it into three particle sizes: 0-3mm accounts for 12%, 3-15mm accounts for 38%, and 15-50mm accounts for 50%, so that the iron minerals and intergrown gangue can be fully liberated.

[0016] Based on the different characteristics of weakly magnetic iron ore with particle sizes of 0-3mm, 3-15mm, and 15-50mm, different refining processes are adopted for processing; among which: Wet coarse-grained pre-refining was carried out on 0-3mm weakly magnetic iron ore using a 600mT strong magnetic field machine, with a refined grade of 47%, a concentrate yield of 23%, and an overall yield of 2.76%. Weakly magnetic iron ore with a particle size of 3-15mm was refined using a 6000GS high-intensity magnetic separator, with a refined grade of 46%, a concentrate yield of 25%, and an overall yield of 9.5%. Weakly magnetic iron ore with a particle size of 15-50mm was refined using an X-ray intelligent sorting device, with a refined grade of 46%, a concentrate yield of 25%, and an overall yield of 12.5%. The final product was a coarse-grained refined concentrate with a grade of 46.11% and a yield of 24.76%.

[0017] The coarse-grained concentrates of 0-3mm, 3-15mm, and 15-50mm particle sizes are crushed and finely ground to -200 mesh (70%). Desliming is then performed to remove fine mud (7.33% grade, 6% yield), resulting in a non-magnetic concentrate with a grade of 49%, a loss on ignition of 19%, an operating yield of 94%, an operating metal recovery rate of 99.89%, and a comprehensive yield of 23.27%. The metal recovery rate reaches 60.49% after deducting the loss on ignition. The processing volume of the strong magnetic separation, roasting weak magnetic separation, and reverse flotation processes can be reduced by 23.27%.

[0018] Example 2 A pre-refining process for coarse-grained weakly magnetic and difficult-to-process iron ore includes the following steps: For weakly magnetic iron ore with an iron content of 32.5% and a particle size of less than 100mm, a hammer crusher is used to crush it to less than 50mm and screen it into three particle sizes: 0-3mm accounts for 12%, 3-15mm accounts for 38%, and 15-50mm accounts for 50%, so that the iron minerals and intergrown gangue can be fully liberated.

[0019] Based on the different characteristics of weakly magnetic iron ore with particle sizes of 0-3mm, 3-15mm, and 15-50mm, different refining processes are adopted for processing; among which: Wet coarse-grained pre-refining was carried out on 0-3mm weakly magnetic iron ore using a 600mT high-intensity magnetic field machine, with a refined grade of 47.6%, a concentrate yield of 23.5%, and an overall yield of 2.82%. Weakly magnetic iron ore with a particle size of 3-15mm was refined using a 6000GS high-intensity magnetic separator, with a refined grade of 46.2%, a concentrate yield of 25.1%, and an overall yield of 9.54%. Weakly magnetic iron ore with a particle size of 15-50mm was refined using an X-ray intelligent sorting device, with a refined grade of 46.7%, a concentrate yield of 25.3%, and an overall yield of 12.65%. Finally, a coarse-grained refined concentrate with a grade of 46.61% and a yield of 25.01% was obtained.

[0020] The coarse-grained concentrates of 0-3mm, 3-15mm, and 15-50mm particle sizes are crushed and finely ground to -200 mesh (70%). Desliming is then performed to remove 4% of the fine mud (6.5% yield) to obtain a non-magnetic concentrate with a grade of 49.6%, a loss on ignition of 19%, an operating yield of 93.5%, an operating metal recovery rate of 99.49%, and a comprehensive yield of 23.38%. The metal recovery rate reaches 61.23% after deducting the loss on ignition. The processing volume of the strong magnetic separation, roasting weak magnetic separation, and reverse flotation processes can be reduced by 23.38%.

Claims

1. A pre-refining process for coarse-grained weakly magnetic, difficult-to-process iron ore, characterized in that, Includes the following steps: Step 1: For weakly magnetic iron ore with an iron content of 32% and a particle size of less than 100mm, use a hammer crusher to crush it to less than 50mm and screen it into three particle sizes: 0-3mm accounting for 12%, 3-15mm accounting for 38%, and 15-50mm accounting for 50%, so that the iron minerals and intergrown gangue can be fully liberated. Step 2: For 0-3mm weakly magnetic iron ore, wet coarse-grained pre-purification is carried out using a 600mT high-intensity magnetic separator, with a purified grade of over 47%; for 3-15mm weakly magnetic iron ore, a 6000GS high-intensity magnetic separator is used for purification, with a purified grade of over 46%; for 15-50mm weakly magnetic iron ore, X-ray intelligent sorting equipment is used for purification, with a purified grade of over 46%. Step 3: Crush and grind the coarse-grained concentrate of each particle size of 0-3mm, 3-15mm, and 15-50mm to -200 mesh 70% and deslim it to obtain a non-magnetic concentrate with a grade of over 49% and a loss on ignition of 19%.

2. The pre-refining process for coarse-grained weakly magnetic, difficult-to-process iron ore according to claim 1, characterized in that, In step 2, a vertical ring high gradient magnetic separator is used for wet refining of 0-3mm weak magnetic iron ore, with a field strength of 600mT and a refined product grade of over 47%. Dry refining of weakly magnetic iron ore with a particle size of 3-15mm using a permanent magnet high-intensity magnetic separator, with a field strength of 700mT, achieves a refined product grade of over 46%. X-ray intelligent sorting equipment is used to refine weakly magnetic iron ore with a particle size of 15-50mm, and iron ore with a grade of over 45% is extracted in advance to achieve a refined grade of over 45%.

3. The pre-refining process for coarse-grained weakly magnetic, difficult-to-process iron ore according to claim 1, characterized in that, Step C involves desliming in a desliming tank, with the desliming grade controlled below 5% and the desliming rate at 8%. The final concentrate grade reaches 49.56%, and after deducting the loss from burning, it is 61.2%.

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