Beneficiation method of a refractory iron ore coexisting with hematite and siderite

Abstract

The application discloses a beneficiation method for a refractory iron ore with coexisting hematite and siderite, and the method comprises the following steps: crushing a weak-magnetic refractory iron ore in a closed circuit to below 100 mm, then sequentially performing three times of dry screening to obtain four particle sizes of <6 mm, 6-15 mm, 15-40 mm and 40-100 mm, preselecting the 6-15 mm particle size by using a dry high-intensity magnetic separator, preselecting the 15-40 mm particle size by using a large bulk jig, preselecting the 40-100 mm particle size by using an optical-electric intelligent separator, preconcentrating the optical-electric intelligent preselected concentrate, combining the preconcentrated products after fine closed circuit crushing of the optical-electric intelligent preselected concentrate to 0-40 mm, then performing super-fine closed circuit crushing to <6 mm, combining the super-fine crushed product with the <6 mm particle size, and then preselecting the combined product by using a coarse-grained wet high-intensity magnetic separator, preconcentrating the preselected concentrate, performing grinding, wet high-intensity magnetic separation, roughing, one-scavenging, roughing, one-concentration and two-scavenging, and finally obtaining a final concentrate. The method has the advantages of large raw ore particle size, large tailing quantity, low energy consumption and good separation effect.

Description

Technical Field

[0001] This invention belongs to the field of weakly magnetic and difficult-to-process iron ore beneficiation technology, specifically involving a beneficiation process for weakly magnetic and difficult-to-process iron ore, which is particularly suitable for the efficient separation of weakly magnetic and difficult-to-process iron ores with a TFe grade between 25% and 35% and iron minerals mainly consisting of hematite and siderite. Background Technology

[0002] Iron ore is a major raw material for the steel industry, primarily distributed in countries such as Australia, Brazil, Russia, and China. Among them, Australian and Brazilian iron ore have relatively high average total iron content (TIP), exceeding 50%; while the average TIP of Chinese iron ore is only 34.5%, far below the world average. China's reserves of complex and difficult-to-process iron ore exceed 20 billion tons, mainly including fine-grained hematite, siderite, limonite, and basaltic hematite. Currently, limonite, siderite, and their associated ores (hematite) are iron ores with large reserves but difficult to beneficiate, typical low-grade and difficult-to-process iron ores. Due to their low quality, fine texture, and complex composition, beneficiation is extremely difficult, resulting in very low utilization rates. The aforementioned complex and difficult-to-process iron ore resources cannot achieve good technical and economic indicators through traditional beneficiation methods. Conventional gravity-magnetic-flotation beneficiation processes yield low iron concentrate recovery rates and grades, resulting in significant resource waste and poor concentrate quality that fails to meet the requirements of refined smelting.

[0003] Currently, the utilization rate of siderite and limonite ore in my country is extremely low, with most being either not recycled or not mined at all. Because siderite has a low theoretical grade and often occurs in isomorphous association with calcium, magnesium, and manganese, it is difficult to achieve an iron concentrate grade of over 45% using physical beneficiation methods. Furthermore, due to the high water content in limonite, it is also difficult to achieve an iron concentrate grade of over 60% using physical beneficiation methods.

[0004] For a long time, mineral processing researchers have conducted extensive research on the beneficiation of iron ore in my country, successfully developing processes such as staged grinding—coarse and fine classification—gravity separation—magnetic separation—anion reverse flotation, and rotary kiln roasting—magnetic separation. However, these processes suffer from numerous drawbacks when processing complex and difficult-to-beneficiate iron ores, including complex process flows, high energy consumption, high reagent costs, and low equipment productivity. In recent years, the developed suspension magnetized roasting—magnetic separation technology has become a promising approach for processing complex and difficult-to-beneficiate iron ores.

[0005] While effective technologies like suspension magnetization roasting and magnetic separation offer advantages such as high-quality roasted products, low energy consumption, and high automation, compared to physical beneficiation methods, suspension magnetization roasting-magnetic separation still has relatively high energy consumption, high production costs, and significant environmental impact from the generated flue gas. Furthermore, the iron grade of the final iron concentrate is not high, making it highly sensitive to iron concentrate prices; a drop in iron concentrate prices could lead to losses and production shutdowns. For example, the article "Experimental Study and Mechanism Research on Suspension Magnetization Roasting of Jiuquan Iron and Steel Ore," published in the 4th issue of *Metal Mines* in 2022, conducted experiments and mechanism research on suspension magnetization roasting. The experimental results showed that at a roasting time of 10...

[0006] Suspension magnetization roasting was carried out under the conditions of min, roasting temperature of 570℃, and CO concentration of 20%. The best indicators of 52.98% iron grade and 83.92% iron recovery rate were obtained by magnetic separation.

[0007] Furthermore, pre-selection is a crucial operation in the beneficiation of low-grade iron ore. By discarding qualified tailings in advance through pre-selection, not only can the grade of the feed beneficiated be increased, but the amount of subsequent processing can also be significantly reduced, achieving the goal of energy conservation and consumption reduction. For a long time, satisfactory pre-selection indicators have been achieved using a single magnetic separation process for strongly magnetic minerals. However, for weakly magnetic minerals such as hematite, limonite, and siderite, the separation effect of using only a single magnetic separation process is much worse than that for strongly magnetic minerals.

[0008] Therefore, there is an urgent need to develop new methods for efficient pre-selection and efficient separation and enrichment of refractory weakly magnetic iron ores containing hematite, limonite, and siderite. Summary of the Invention

[0009] The purpose of this invention is to address the technical difficulties of existing technologies, such as the inability to pre-select and discard weakly magnetic iron minerals, poor separation effect for coarse particles of 50mm and fine particles of less than 6mm, and small processing capacity, by providing a method for beneficiating difficult-to-process iron ore containing hematite and siderite.

[0010] To achieve the above-mentioned objectives of this invention, a method for beneficiating refractory iron ore containing hematite and siderite is provided, comprising the following steps:

[0011] S1 involves medium-closed crushing of weakly magnetic, difficult-to-process iron ore with a TFe grade between 25% and 35% and iron minerals mainly consisting of hematite and siderite to a size of less than 100 mm, followed by three dry screenings to obtain four particle sizes: <6 mm, 6~15 mm, 15~40 mm, and 40~100 mm.

[0012] S2 involves pre-selecting and discarding the tailings of the three particle sizes (6-15mm, 15-40mm, and 40-100mm) obtained in step S1 using different pre-selection equipment. Specifically, the 6-15mm particle size is pre-selected using a dry high-intensity magnetic separator to obtain dry high-intensity magnetic pre-selection concentrate and discharge dry high-intensity magnetic tailings. The 15-40mm particle size is pre-selected using a large-block jig to obtain jig pre-selection concentrate and discharge jig pre-selection tailings. The 40-100mm particle size is pre-selected using a photoelectric intelligent separator to obtain photoelectric intelligent pre-selection concentrate and discharge photoelectric intelligent pre-selection tailings.

[0013] S3 The photoelectric intelligent pre-selection concentrate obtained in step S2 is finely crushed in a closed circuit to 0~40mm and then combined with the jigging pre-selection concentrate obtained in step S2. Then it is ultra-finely crushed in a closed circuit to <6mm. The ultra-finely crushed product is then combined with the <6mm particle size obtained in step S1 and subjected to wet strong magnetic pre-selection using a coarse wet strong magnetic separator to obtain wet strong magnetic pre-selection concentrate and discharge wet strong magnetic tailings.

[0014] S4 combines the dry strong magnetic pre-selection concentrate obtained in step S2 with the wet strong magnetic pre-selection concentrate obtained in step S3 as the final pre-selection concentrate. The dry strong magnetic tailings, jigging pre-selection tailings, photoelectric intelligent pre-selection tailings discharged in step S2 and the wet strong magnetic tailings discharged in step S3 are combined as the final pre-selection tailings.

[0015] S5 Grind the final pre-selected concentrate obtained in step S4, and then pass the grinding product through fine-particle wet strong magnetic coarse-scan separation to discharge the fine-particle wet strong magnetic coarse separation tailings and fine-particle wet strong magnetic clean separation tailings to obtain fine-particle wet strong magnetic clean concentrate.

[0016] S6 feeds the fine-grained wet strong magnetic concentrate obtained in step S5 into a roughing, cleaning, and scavenging reverse flotation operation to obtain the final iron concentrate and discharge the reverse flotation scavenging tailings; the reverse flotation scavenging tailings are combined with the fine-grained wet strong magnetic roughing tailings and fine-grained wet strong magnetic concentrate tailings discharged in step S5 to form the final fine-grained tailings.

[0017] Preferably, in step S1, the intermediate crushing equipment is a jaw crusher, and the screen forming a closed circuit with the intermediate crushing equipment is a linear vibrating screen with a screen aperture size of 100mm; the screens for the three-stage dry screening are also linear vibrating screens with screen aperture sizes of 40mm, 15mm, and 6mm respectively; the dry high-intensity magnetic separator is a permanent magnet roller type high-intensity magnetic powder dry separator with a maximum feed particle size of 20mm; the magnetic field strength on the drum surface is 11000-13000 Oe, preferably 12000 Oe; the frequency of the drum frequency converter is 28-32Hz, preferably 30Hz. HZ is preferred; the large block jigging machine is a diaphragm type large block jigging machine with a jigging frequency of 130-150 times / min and a jigging stroke of 90-110mm; the photoelectric intelligent sorting machine is an XNDT-104 type fully automatic intelligent online sorting machine with a belt width of 1.5-1.7m, preferably 1.6m; and a belt speed of 3-4m / s.

[0018] In addition, the photoelectric intelligent sorting machine mentioned in step S2 can also be a HOT intelligent X-ray sorting machine.

[0019] Preferably, in step S3, the fine crushing equipment is a jaw crusher, and the screen forming a closed circuit with it is a linear vibrating screen with a screen aperture size of 40mm; the ultrafine crushing equipment is a high-pressure roller mill, and the screen forming a closed circuit with it is a linear vibrating screen with a screen aperture size of 6mm; the coarse wet high-intensity magnetic separator is a Slon coarse vertical ring pulsating high gradient magnetic separator with a maximum feed particle size of 6mm, a magnetic field strength of 954~1194KA / m, a ring rotation speed of 2~4 rpm, and a pulsation frequency of 40~80 times / minute.

[0020] Preferably, in step S5, the grinding operation uses a wet ball mill with a grinding fineness of -0.076mm 80% to 95%; the fine-particle wet strong magnetic roughing and fine-particle wet strong magnetic scavenging both use a fine-particle pulsating high-gradient magnetic separator with a roughing magnetic field strength of 0.8 to 1.2T and a roughing magnetic field strength of 1.0 to 1.4T.

[0021] Preferably, in step S6, the reagent regime for the reverse flotation roughing is as follows: NaOH dosage 800-1200 g / t flotation feed, CaO dosage 200-400 g / t flotation feed, starch dosage 800-1200 g / t flotation feed, and sodium oleate dosage 1000-1500 g / t flotation feed; the reagent regime for the reverse flotation cleaning is as follows: sodium oleate dosage 500-1000 g / t flotation feed; no reagents are added for the reverse flotation scavenging operation.

[0022] In addition, in step S6, the reagent regime for the reverse flotation roughing can be as follows: NaOH dosage 500-800 g / t flotation feed, starch dosage 500-800 g / t flotation feed, and collector dosage 300-600 g / t; the reagent regime for the reverse flotation cleaning is as follows: collector dosage 100-250 g / t flotation feed; the reagent regime for the reverse flotation cleaning is as follows: collector dosage 120-200 g / t flotation feed; no reagent is added for the reverse flotation scavenging operation. The collector is prepared by heating a solution of dodecylamine and glacial acetic acid at a mass ratio of 4:0.9-4:1.1 with hot water at 80-100℃.

[0023] Furthermore, to further realize the resource utilization of tailings and reduce the final fine tailings discharge, the photoelectric intelligent pre-selection tailings and jigging pre-selection tailings discharged in step S2 are sold as building aggregate products. In this case, the dry strong magnetic tailings discharged in step S2 and the wet strong magnetic tailings discharged in step S3 are combined and then fed into dry screening and wet screening respectively to obtain tailings of three particle sizes: +4.75mm, 0.5~4.75mm, and -0.5mm. The +4.75mm tailings are sold as building aggregate products, and the 0.5~4.75mm tailings are sold as building sand products. The reverse flotation scavenging tailings discharged in step S6 are combined with the -0.5mm tailings discharged in step S4 to form the final fine tailings.

[0024] Compared with existing technologies, the present invention provides a method for beneficiating refractory iron ore containing both hematite and siderite, which has the following advantages:

[0025] (1) The present invention combines pre-selection process for precise grading, organically integrating different pre-selection methods and equipment, and realizing effective pre-selection of weak magnetic refractory iron ore in a wide range of particle sizes (0-100mm). Specifically, the 6-15mm particle size is pre-selected by a dry strong magnetic separator, the 15-40mm particle size is pre-selected by a large block jig, the 40-100mm particle size is pre-selected by a photoelectric intelligent separator, and the <6mm particle size is pre-selected by a coarse wet strong magnetic separator. By organically integrating multiple pre-selection methods (magnetic separation, gravity separation, and photoelectric separation), the present invention realizes effective pre-selection of weak magnetic iron ore in a wide range of particle sizes (0-100mm), solving the problem of narrow effective pre-selection particle size of traditional single pre-selection methods, greatly improving the separation accuracy, and finally the iron grade of the pre-selected concentrate is more than 9 percentage points higher than the iron grade of the raw weak magnetic refractory iron ore.

[0026] (2) The combined pre-selection process of this invention adopts different pre-selection methods for different particle size ore characteristics, which can give full play to the performance of various pre-selection equipment and effectively improve the separation effect. For example, this invention uses photoelectric intelligent pre-selection for large ore pieces of 40-100mm, which solves the problem that if strong magnetic pre-selection is used for this particle size, the metal recovery rate will be significantly lower because the centrifugal force on the mineral is much greater than the magnetic force. At the same time, since photoelectric intelligent pre-selection requires single-layer material distribution, using photoelectric intelligent pre-selection for large ore pieces of 40-100mm also effectively improves the hourly processing capacity of photoelectric intelligent pre-selection. For example, for fine particles of 0-6mm, because of their fine particle size and easy agglomeration, the dry strong magnetic pre-selection effect is very poor. Therefore, this invention uses a coarse wet strong magnetic separator for wet strong magnetic pre-selection.

[0027] (3) The combined pre-selection process of the present invention uses intelligent pre-selection and jigging pre-selection to discard large tailings, achieving the goal of "discarding as early as possible", thereby effectively reducing the energy consumption of subsequent crushing. At the same time, after the concentrate of intelligent pre-selection and jigging pre-selection is crushed again, wet strong magnetic pre-selection is used to discard the tailings, which further increases the amount of tailings discarded and also improves the grade of the final pre-selected concentrate.

[0028] (4) Compared with the traditional single pre-selection process, the combined pre-selection process of the present invention has the advantages of large feed particle size, wide particle size range, large tailings, high concentrate grade and low energy consumption.

[0029] (5) Compared with the traditional single pre-selection process, the combined pre-selection process of the present invention has the advantages of large particle size, wide particle size range, large tailings volume, and low energy consumption, with a tailings yield of up to 33% or more.

[0030] (6) The final pre-selected tailings are fed into dry screening to obtain +4.75mm building aggregate, 0.5~4.75mm building sand, and -0.5mm particle size.

[0031] (7) The present invention uses a pure physical beneficiation process of grinding-strong magnetic separation-reverse flotation to obtain qualified concentrate for pre-selected concentrate. Compared with the traditional roasting-magnetic separation process for siderite and limonite, it has the advantages of low production cost, low energy consumption and low environmental pollution.

[0032] (8) In addition, the photoelectric intelligent pre-selected tailings and jigging pre-selected tailings discharged by the method of the present invention are sold as building aggregate products; the dry strong magnetic tailings discharged in step S2 and the wet strong magnetic tailings discharged in step S3 are combined and fed into dry screening and wet screening in sequence, which can respectively obtain building aggregate products with a particle size of +4.75mm and building sand products with a particle size of 0.5 to 4.75mm, thereby greatly improving the resource utilization rate. The yield of the obtained building aggregate products—jigging pre-selected tailings, photoelectric intelligent pre-selected tailings, +4.75mm tailings and 0.5 to 4.75mm building sand products—accounts for more than 28% of the raw ore. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the pre-selection process principle of a beneficiation method for refractory iron ore containing hematite and siderite, as described in this invention.

[0034] Figure 2 This is a flow chart illustrating the pre-selection process of a refractory iron ore beneficiation method for a coexisting hematite and siderite ore according to the present invention.

[0035] Figure 3 This invention presents a process flow diagram illustrating the principle of grinding the final pre-selected concentrate, followed by strong magnetic separation and reverse flotation, in a method for beneficiating refractory iron ore containing hematite and siderite. Detailed Implementation

[0036] To further describe the present invention, a method for beneficiating refractory iron ore containing hematite and siderite is described in detail below with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the embodiments.

[0037] The ore sample used in this embodiment is a weakly magnetic iron ore from an iron mine in western China. The iron minerals in this ore are mainly hematite and siderite, which together account for more than 95% of the iron minerals, making it a typical weakly magnetic and difficult-to-process iron ore. The results of multi-element analysis and iron phase analysis of this ore are shown in Tables 1 and 2.

[0038] Table 1. Results of multi-element analysis of raw ore (%)

[0039] element TFe <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO MgO S P MnO content 32.51 26.05 2.85 1.14 1.07 1.18 0.025 1.07 element <![CDATA[K2O]]> <![CDATA[Na2O]]> ZnO NiO <![CDATA[TiO2]]> <![CDATA[V2O5]]> <![CDATA[Cr2O3]]> burn damage content 0.881 0.047 0.040 0.005 0.195 0.008 0.003 12.92

[0040] Table 2. Results of iron phase analysis in raw ore (%)

[0041] Prime Minister magnetite goethite Siderite Ferric silicate Pyrite Pyrrhotite total iron content 0.50 21.41 9.68 0.52 0.31 0.0022 32.42 Iron distribution 1.54 66.04 29.85 1.60 0.96 0.01 100.00

[0042] Depend on Figure 1 The diagram shown is a flowchart illustrating the pre-selection process principles of a beneficiation method for refractory iron ore containing hematite and siderite, as described in this invention. Figure 2 , Figure 3 As can be seen, the specific implementation steps adopted in the embodiment of the refractory iron ore beneficiation method of the present invention, which involves the coexistence of hematite and siderite, are as follows:

[0043] (1) The ore is crushed in a closed circuit to less than 100 mm, and then subjected to three dry screenings to obtain four particle sizes: 0-6 mm, 6-15 mm, 15-40 mm, and 40-100 mm.

[0044] (2) The 6-15mm particle size from step (1) is pre-selected by dry strong magnetic separation using a permanent magnet roller dry separator, the 15-40mm particle size is pre-selected by jigging using a diaphragm jig, and the 40-100mm particle size is pre-selected by photoelectric intelligent separation using a photoelectric intelligent separator. The discharged jigging pre-selected tailings and photoelectric intelligent pre-selected tailings can be sold as building aggregate products.

[0045] (3) After the photoelectric intelligent pre-selection concentrate obtained in step (2) is finely crushed to 0-40 mm in a closed circuit, it is combined with the jigging pre-selection concentrate obtained in step (2), and then ultra-fine crushed to 0-6 mm in a closed circuit. The ultra-fine crushed product is then combined with the 0-6 mm particle size in step (1) and then wet strong magnetic pre-selection is performed.

[0046] (4) Combine the dry strong magnetic pre-selection concentrate obtained in step (2) with the wet strong magnetic pre-selection concentrate obtained in step (3) as the final pre-selection concentrate. Combine the dry strong magnetic pre-selection tailings, jigging pre-selection tailings, photoelectric intelligent pre-selection tailings obtained in step (2) with the wet strong magnetic pre-selection tailings obtained in step (3) as the final pre-selection tailings.

[0047] (5) Grind the final pre-selected concentrate obtained in step (4), and then pass the grinding product through fine-particle wet strong magnetic coarse-scan separation to discharge the fine-particle wet strong magnetic coarse separation tailings and fine-particle wet strong magnetic fine separation tailings to obtain fine-particle wet strong magnetic fine separation concentrate.

[0048] (6) The fine-grained wet strong magnetic concentrate obtained in step (5) is fed into the first roughing, first cleaning and second scavenging reverse flotation operation to obtain the final iron concentrate and discharge the reverse flotation scavenging tailings; the reverse flotation scavenging tailings are combined with the fine-grained wet strong magnetic roughing tailings and fine-grained wet strong magnetic concentrate tailings discharged in step S5 to form the final fine-grained tailings.

[0049] The intermediate crushing equipment in step (1) is a jaw crusher, and the screen that forms a closed circuit with it is a linear vibrating screen with a screen hole size of 100mm; the screens for the three-stage dry screening are also linear vibrating screens with screen hole sizes of 40mm, 15mm and 6mm respectively.

[0050] The dry strong magnetic pre-selection equipment in step (2) is a permanent magnet roller strong magnetic powder dry separator with a maximum feed particle size of 20mm, a magnetic field strength of 12000 Oe on the drum surface, and a drum frequency converter frequency of 30HZ.

[0051] The jigging pre-selection equipment in step (2) is a diaphragm-type large block jigging machine with a jigging stroke of 135 times / min and a jigging stroke of 105mm; the photoelectric intelligent sorting machine is an XNDT-104 type intelligent pre-selection machine with a belt width of 1.6m and a belt speed of 3.5m / s.

[0052] The fine crushing equipment in step (3) is a jaw crusher, and the screen forming a closed circuit with it is a linear vibrating screen with a screen aperture size of 40mm; the ultrafine crushing equipment is a high-pressure roller mill, and the screen forming a closed circuit with it is a linear vibrating screen with a screen aperture size of 6mm; the wet strong magnetic pre-selection equipment is a Slon coarse vertical ring pulsating high gradient magnetic separator with a maximum feed particle size of 6mm, a magnetic field strength of 1114 KA / m, a ring rotation speed of 3 revolutions / minute, and a pulsation frequency of 60 times / minute.

[0053] In step (5), the grinding operation adopts a wet ball mill with a grinding fineness of -0.076mm90%; the fine particle wet strong magnetic roughing and fine particle wet strong magnetic sweeping both adopt a fine particle pulsating high gradient magnetic separator with a roughing magnetic field strength of 1.0T and a roughing magnetic field strength of 1.2T.

[0054] In step (6), the reagent system for reverse flotation roughing is as follows: NaOH dosage is 1000 g / t flotation feed, CaO dosage is 300 g / t flotation feed, starch dosage is 1000 g / t flotation feed, and sodium oleate dosage is 1300 g / t flotation feed; the reagent system for reverse flotation cleaning is as follows: sodium oleate dosage is 600 g / t flotation feed; no reagents are added for reverse flotation scavenging.

[0055] After processing with the above-mentioned process, the weakly magnetic iron ore with an iron grade of 32.60% can have its qualified tailings (yield of 33.31% and iron grade of 14.49%) discarded in advance. The resulting pre-selected concentrate has an iron grade of 41.64%, which is more than 9 percentage points higher than that of the original ore, and the iron recovery rate of the concentrate is 85.19%. After the pre-selected concentrate is processed by grinding, fine-grained wet strong magnetic flotation, roughing and scavenging, and reverse flotation (roughing, cleaning, and scavenging), the final concentrate has an iron grade of 63.12%, the iron recovery rate of the grinding and beneficiation operation is 80.52%, and the iron grade of the grinding and beneficiation tailings is 17.30%.

[0056] In addition, a novel high-efficiency iron ore reverse flotation collector was used. In the embodiment, the novel high-efficiency iron ore reverse flotation collector was prepared by heating a solution of dodecylamine and glacial acetic acid at a mass ratio of 4:1 with hot water at 90°C. In step (6) of using the novel high-efficiency iron ore reverse flotation collector, the reagent system for the roughing stage of reverse flotation was as follows: NaOH dosage 600 g / t flotation feed, starch dosage 700 g / t flotation feed, and collector dosage 450 g / t flotation feed; the reagent system for the cleaning stage of reverse flotation was as follows: collector dosage 100-250 g / t flotation feed; the reagent system for the finishing stage of reverse flotation was as follows: collector dosage 120 g / t-200 g / t flotation feed; no reagent was added for the scavenging stage of reverse flotation. The final iron grade of the concentrate obtained was 63.52%, and the iron recovery rate of the grinding operation was 81.63%.

[0057] Furthermore, in this embodiment, the dry strong magnetic tailings discharged from step S2 and the wet strong magnetic tailings discharged from step S3 are combined and then sequentially fed into dry screening and wet screening to obtain tailings of three particle sizes: +4.75mm, 0.5-4.75mm, and -0.5mm. The +4.75mm tailings are sold as building aggregate, and the 0.5-4.75mm tailings are sold as building sand. The yield of the obtained building aggregate products—jigging pre-selected tailings, photoelectric intelligent pre-selected tailings, +4.75mm tailings, and 0.5-4.75mm building sand—accounts for 28.5% of the original ore yield.

[0058] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for beneficiating refractory iron ore containing hematite and siderite, characterized in that... The following steps are adopted: S1 involves medium-closed crushing of weakly magnetic, difficult-to-process iron ore with a TFe grade between 25% and 35% and iron minerals mainly consisting of hematite and siderite to a size of less than 100 mm, followed by three dry screenings to obtain four particle sizes: <6 mm, 6~15 mm, 15~40 mm, and 40~100 mm. S2 involves separately pre-selecting and discarding the tailings from the three particle sizes (6-15mm, 15-40mm, and 40-100mm) obtained in step S1 using different pre-selection equipment. Specifically, the 6-15mm particle size is pre-selected using a dry high-intensity magnetic separator to obtain a dry high-intensity magnetic pre-selection concentrate and discharge the dry high-intensity magnetic tailings. The 15-40mm particle size is pre-selected using a large-scale jig to obtain a jig pre-selection concentrate and discharge the jig pre-selection tailings. The 40-100mm particle size is pre-selected using a photoelectric intelligent separator to obtain a photoelectric intelligent pre-selection concentrate and discharge the photoelectric intelligent intelligent tailings. The dry high-intensity magnetic separator is a permanent magnet roller-type high-intensity magnetic powder dry separator with a maximum feed particle size of 20mm and a surface magnetic field strength of 11000-13000. Oe, the frequency of the drum inverter is 28-32HZ; the large block jig is a diaphragm type large block jig, the jig stroke is 130-150 times / min, and the jig stroke is 90-110mm. S3 The photoelectric intelligent pre-selection concentrate obtained in step S2 is finely crushed in a closed circuit to 0~40mm and then combined with the jigging pre-selection concentrate obtained in step S2. Then it is ultra-finely crushed in a closed circuit to <6mm. The ultra-finely crushed product is then combined with the <6mm particle size obtained in step S1 and subjected to wet strong magnetic pre-selection using a coarse wet strong magnetic separator to obtain wet strong magnetic pre-selection concentrate and discharge wet strong magnetic tailings. S4 combines the dry strong magnetic pre-selection concentrate obtained in step S2 with the wet strong magnetic pre-selection concentrate obtained in step S3 as the final pre-selection concentrate. The dry strong magnetic tailings, jigging pre-selection tailings, photoelectric intelligent pre-selection tailings discharged in step S2 and the wet strong magnetic tailings discharged in step S3 are combined as the final pre-selection tailings. S5. The final pre-selected concentrate obtained in step S4 is ground, and then the grinding product is subjected to fine-particle wet strong magnetic separation with roughing and scavenging. The tailings of fine-particle wet strong magnetic roughing and fine-particle wet strong magnetic cleaning are discharged separately to obtain fine-particle wet strong magnetic clean concentrate. The grinding operation uses a wet ball mill with a grinding fineness of -0.076mm 80%~95%. Both fine-particle wet strong magnetic roughing and fine-particle wet strong magnetic scavenging use fine-particle pulsed high-gradient magnetic separators with a roughing magnetic field strength of 0.8~1.2T and a roughing magnetic field strength of 1.0~1.4T. S6 feeds the fine-grained wet high-intensity magnetic refining concentrate obtained in step S5 into a first rougher, first cleaner, and second scavenger reverse flotation operation to obtain the final iron concentrate and discharge the reverse flotation scavenger tailings. The reverse flotation scavenger tailings, together with the fine-grained wet high-intensity magnetic rougher tailings and fine-grained wet high-intensity magnetic refining tailings discharged from step S5, are combined into the final fine-grained tailings. The reagent regime for the reverse flotation rougher is as follows: NaOH dosage 800-1200 g / t flotation feed, CaO dosage 200-400 g / t flotation feed, starch dosage 800-1200 g / t flotation feed, and sodium oleate dosage 1000-1500 g / t flotation feed. The reagent regime for the reverse flotation cleaner is as follows: sodium oleate dosage 500-1000 g / t flotation feed. No reagents are added during the reverse flotation scavenger operation.

2. A method for beneficiating refractory iron ore containing hematite and siderite, characterized in that... The following steps are adopted: S1 involves medium-closed crushing of weakly magnetic, difficult-to-process iron ore with a TFe grade between 25% and 35% and iron minerals mainly consisting of hematite and siderite to a size of less than 100 mm, followed by three dry screenings to obtain four particle sizes: <6 mm, 6~15 mm, 15~40 mm, and 40~100 mm. S2 involves separately pre-selecting and discarding the tailings from the three particle sizes (6-15mm, 15-40mm, and 40-100mm) obtained in step S1 using different pre-selection equipment. Specifically, the 6-15mm particle size is pre-selected using a dry high-intensity magnetic separator to obtain a dry high-intensity magnetic pre-selection concentrate and discharge the dry high-intensity magnetic tailings. The 15-40mm particle size is pre-selected using a large-scale jig to obtain a jig pre-selection concentrate and discharge the jig pre-selection tailings. The 40-100mm particle size is pre-selected using a photoelectric intelligent separator to obtain a photoelectric intelligent pre-selection concentrate and discharge the photoelectric intelligent intelligent tailings. The dry high-intensity magnetic separator is a permanent magnet roller-type high-intensity magnetic powder dry separator with a maximum feed particle size of 20mm and a surface magnetic field strength of 11000-13000. Oe, the frequency of the drum inverter is 28-32HZ; the large block jig is a diaphragm type large block jig, the jig stroke is 130-150 times / min, and the jig stroke is 90-110mm. S3 The photoelectric intelligent pre-selection concentrate obtained in step S2 is finely crushed in a closed circuit to 0~40mm and then combined with the jigging pre-selection concentrate obtained in step S2. Then it is ultra-finely crushed in a closed circuit to <6mm. The ultra-finely crushed product is then combined with the <6mm particle size obtained in step S1 and subjected to wet strong magnetic pre-selection using a coarse wet strong magnetic separator to obtain wet strong magnetic pre-selection concentrate and discharge wet strong magnetic tailings. S4 combines the dry strong magnetic pre-selection concentrate obtained in step S2 with the wet strong magnetic pre-selection concentrate obtained in step S3 as the final pre-selection concentrate. The dry strong magnetic tailings, jigging pre-selection tailings, photoelectric intelligent pre-selection tailings discharged in step S2 and the wet strong magnetic tailings discharged in step S3 are combined as the final pre-selection tailings. S5. The final pre-selected concentrate obtained in step S4 is ground, and then the grinding product is subjected to fine-particle wet strong magnetic separation with roughing and scavenging. The tailings of fine-particle wet strong magnetic roughing and fine-particle wet strong magnetic cleaning are discharged separately to obtain fine-particle wet strong magnetic clean concentrate. The grinding operation uses a wet ball mill with a grinding fineness of -0.076mm 80%~95%. Both fine-particle wet strong magnetic roughing and fine-particle wet strong magnetic scavenging use fine-particle pulsed high-gradient magnetic separators with a roughing magnetic field strength of 0.8~1.2T and a roughing magnetic field strength of 1.0~1.4T. S6. The fine-grained wet high-intensity magnetic refining concentrate obtained in step S5 is fed into a first roughing, first cleaning, and second scavenging reverse flotation operation to obtain the final iron concentrate, and the reverse flotation scavenging tailings are discharged. The reverse flotation scavenging tailings, together with the fine-grained wet high-intensity magnetic refining tailings and fine-grained wet high-intensity magnetic refining tailings discharged from step S5, are combined into the final fine-grained tailings. The reagent regime for the reverse flotation roughing is: NaOH dosage 500-800 g / t flotation feed, starch dosage 500-800 g / t flotation feed, and collector dosage 300-600 g / t flotation feed. The reagent regime for the reverse flotation cleaning is: collector dosage 100-250 g / t flotation feed. g / t flotation feed; the reagent system for reverse flotation cleaning is as follows: collector dosage is 120g / t~200g / t flotation feed; no reagent is added for reverse flotation scavenging operation; the collector is prepared by heating dodecylamine and glacial acetic acid solution at a mass ratio of 4:0.9~4:1.1 with hot water at 80~100℃.

3. A method for beneficiating refractory iron ore containing both hematite and siderite, characterized in that... The following steps are adopted: S1 involves medium-closed crushing of weakly magnetic, difficult-to-process iron ore with a TFe grade between 25% and 35% and iron minerals mainly consisting of hematite and siderite to a size of less than 100 mm, followed by three dry screenings to obtain four particle sizes: <6 mm, 6~15 mm, 15~40 mm, and 40~100 mm. S2 involves separately pre-selecting and discarding the tailings from the three particle sizes (6-15mm, 15-40mm, and 40-100mm) obtained in step S1 using different pre-selection equipment. The 6-15mm particle size is pre-selected using a dry high-intensity magnetic separator to obtain dry high-intensity magnetic pre-selection concentrate and discharge dry high-intensity magnetic tailings. The 15-40mm particle size is pre-selected using a large-particle jig to obtain jigging pre-selection concentrate and discharge jigging pre-selection tailings. The 40-100mm particle size is pre-selected using a photoelectric intelligent separator to obtain photoelectric intelligent pre-selection concentrate and discharge photoelectric intelligent pre-selection tailings. The discharged jigging pre-selection tailings and photoelectric intelligent pre-selection tailings are sold as building aggregate products. The dry high-intensity magnetic separator is a permanent magnet roller-type high-intensity magnetic powder dry separator with a maximum feed particle size of 20mm and a surface magnetic field strength of 11000-13000. Oe, the frequency of the drum inverter is 28-32HZ; the large block jig is a diaphragm type large block jig, the jig stroke is 130-150 times / min, and the jig stroke is 90-110mm. S3 The photoelectric intelligent pre-selection concentrate obtained in step S2 is finely crushed in a closed circuit to 0~40mm and then combined with the jigging pre-selection concentrate obtained in step S2. Then it is ultra-finely crushed in a closed circuit to <6mm. The ultra-finely crushed product is then combined with the <6mm particle size obtained in step S1 and subjected to wet strong magnetic pre-selection using a coarse wet strong magnetic separator to obtain wet strong magnetic pre-selection concentrate and discharge wet strong magnetic tailings. S4 combines the dry strong magnetic pre-selection concentrate obtained in step S2 with the wet strong magnetic pre-selection concentrate obtained in step S3 as the final pre-selection concentrate. The dry strong magnetic tailings discharged from step S2 and the wet strong magnetic tailings discharged from step S3 are then fed into dry screening and wet screening respectively to obtain tailings of three particle sizes: +4.75mm, 0.5~4.75mm, and -0.5mm. The +4.75mm tailings are sold as building aggregate products, and the 0.5~4.75mm tailings are sold as building sand products. S5. The final pre-selected concentrate obtained in step S4 is ground, and then the grinding product is subjected to fine-particle wet strong magnetic separation with roughing and scavenging. The tailings of fine-particle wet strong magnetic roughing and fine-particle wet strong magnetic cleaning are discharged separately to obtain fine-particle wet strong magnetic clean concentrate. The grinding operation uses a wet ball mill with a grinding fineness of -0.076mm 80%~95%. Both fine-particle wet strong magnetic roughing and fine-particle wet strong magnetic scavenging use fine-particle pulsed high-gradient magnetic separators with a roughing magnetic field strength of 0.8~1.2T and a roughing magnetic field strength of 1.0~1.4T. S6 feeds the fine-grained wet strong magnetic concentrate obtained in step S5 into a first roughing, first cleaning, and second scavenging reverse flotation operation to obtain the final iron concentrate and discharge the reverse flotation scavenging tailings. The reverse flotation scavenging tailings are combined with the -0.5mm tailings discharged in step S4 to form the final fine-grained tailings. The reagent regime for the reverse flotation roughing is as follows: NaOH dosage 800-1200 g / t flotation feed, CaO dosage 200-400 g / t flotation feed, starch dosage 800-1200 g / t flotation feed, and sodium oleate dosage 1000-1500 g / t flotation feed. The reagent regime for the reverse flotation cleaning is as follows: sodium oleate dosage 500-1000 g / t flotation feed. No reagents are added during the reverse flotation scavenging operation.

4. A method for beneficiating refractory iron ore containing hematite and siderite, characterized in that... The following steps are adopted: S1 involves medium-closed crushing of weakly magnetic, difficult-to-process iron ore with a TFe grade between 25% and 35% and iron minerals mainly consisting of hematite and siderite to a size of less than 100 mm, followed by three dry screenings to obtain four particle sizes: <6 mm, 6~15 mm, 15~40 mm, and 40~100 mm. S2 involves separately pre-selecting and discarding the tailings from the three particle sizes (6-15mm, 15-40mm, and 40-100mm) obtained in step S1 using different pre-selection equipment. The 6-15mm particle size is pre-selected using a dry high-intensity magnetic separator to obtain dry high-intensity magnetic pre-selection concentrate and discharge dry high-intensity magnetic tailings. The 15-40mm particle size is pre-selected using a large-particle jig to obtain jigging pre-selection concentrate and discharge jigging pre-selection tailings. The 40-100mm particle size is pre-selected using a photoelectric intelligent separator to obtain photoelectric intelligent pre-selection concentrate and discharge photoelectric intelligent pre-selection tailings. The discharged jigging pre-selection tailings and photoelectric intelligent pre-selection tailings are sold as building aggregate products. The dry high-intensity magnetic separator is a permanent magnet roller-type high-intensity magnetic powder dry separator with a maximum feed particle size of 20mm and a surface magnetic field strength of 11000-13000. Oe, the frequency of the drum inverter is 28-32HZ; the large block jig is a diaphragm type large block jig, the jig stroke is 130-150 times / min, and the jig stroke is 90-110mm. S3 The photoelectric intelligent pre-selection concentrate obtained in step S2 is finely crushed in a closed circuit to 0~40mm and then combined with the jigging pre-selection concentrate obtained in step S2. Then it is ultra-finely crushed in a closed circuit to <6mm. The ultra-finely crushed product is then combined with the <6mm particle size obtained in step S1 and subjected to wet strong magnetic pre-selection using a coarse wet strong magnetic separator to obtain wet strong magnetic pre-selection concentrate and discharge wet strong magnetic tailings. S4 combines the dry strong magnetic pre-selection concentrate obtained in step S2 with the wet strong magnetic pre-selection concentrate obtained in step S3 as the final pre-selection concentrate. The dry strong magnetic tailings discharged from step S2 and the wet strong magnetic tailings discharged from step S3 are then fed into dry screening and wet screening respectively to obtain tailings of three particle sizes: +4.75mm, 0.5~4.75mm, and -0.5mm. The +4.75mm tailings are sold as building aggregate products, and the 0.5~4.75mm tailings are sold as building sand products. S5. The final pre-selected concentrate obtained in step S4 is ground, and then the grinding product is subjected to fine-particle wet strong magnetic separation with roughing and scavenging. The tailings of fine-particle wet strong magnetic roughing and fine-particle wet strong magnetic cleaning are discharged separately to obtain fine-particle wet strong magnetic clean concentrate. The grinding operation uses a wet ball mill with a grinding fineness of -0.076mm 80%~95%. Both fine-particle wet strong magnetic roughing and fine-particle wet strong magnetic scavenging use fine-particle pulsed high-gradient magnetic separators with a roughing magnetic field strength of 0.8~1.2T and a roughing magnetic field strength of 1.0~1.4T. S6 feeds the fine-grained wet strong magnetic concentrate obtained in step S5 into a first rougher, first cleaner, and second scavenger reverse flotation operation to obtain the final iron concentrate, and discharges the reverse flotation scavenger tailings; the reverse flotation scavenger tailings are combined with the -0.5mm tailings discharged in step S4 to form the final fine-grained tailings; the reagent regime for the reverse flotation rougher is: NaOH dosage 500-800g / t flotation feed, starch dosage 500-800g / t flotation feed, and collector dosage 300g / t-600g / t flotation feed; the reagent regime for the reverse flotation cleaner is: collector dosage 100-250g / t flotation feed. g / t flotation feed; the reagent system for reverse flotation cleaning is as follows: collector dosage is 120g / t~200g / t flotation feed; no reagent is added for reverse flotation scavenging operation; the collector is prepared by heating dodecylamine and glacial acetic acid solution at a mass ratio of 4:0.9~4:1.1 with hot water at 80~100℃.

5. A beneficiation method for refractory iron ore containing hematite and siderite as described in claim 1, 2, 3, or 4, characterized in that: In step S1, the intermediate crushing equipment uses a jaw crusher, and the screen forming a closed circuit with the intermediate crushing equipment is a linear vibrating screen with a screen aperture size of 100mm; the screens for the three-stage dry screening are also linear vibrating screens with screen aperture sizes of 40mm, 15mm and 6mm respectively.

6. A method for beneficiating refractory iron ore containing hematite and siderite as described in claim 1, 2, 3, or 4, characterized in that: In step S2, the photoelectric intelligent sorting machine is the XNDT-104 fully automatic intelligent online sorting machine, with a belt width of 1.5 to 1.7 m and a belt speed of 3 to 4 m / s.

7. A method for beneficiating refractory iron ore containing hematite and siderite as described in claim 1, 2, 3, or 4, characterized in that: In step S3, the fine crushing equipment is a jaw crusher, and the screen forming a closed circuit with it is a linear vibrating screen with a screen aperture size of 40mm; the ultrafine crushing equipment is a high-pressure roller mill, and the screen forming a closed circuit with it is a linear vibrating screen with a screen aperture size of 6mm; the coarse wet high-intensity magnetic separator is a Slon coarse vertical ring pulsating high gradient magnetic separator, with a maximum feed particle size of 6mm, a magnetic field strength of 954~1194KA / m, a ring rotation speed of 2~4 rpm, and a pulsation frequency of 40~80 times / minute.

8. A method for beneficiating refractory iron ore containing hematite and siderite as described in claim 1, 2, 3, or 4, characterized in that: In step S1, the intermediate crushing equipment uses a jaw crusher, and the screen forming a closed circuit with the intermediate crushing equipment is a linear vibrating screen with a screen aperture size of 100mm; the screens for the three-stage dry screening are also linear vibrating screens with screen aperture sizes of 40mm, 15mm and 6mm respectively. In step S2, the photoelectric intelligent sorting machine is the XNDT-104 fully automatic intelligent online sorting machine, with a belt width of 1.5 to 1.7 m and a belt speed of 3 to 4 m / s; In step S3, the fine crushing equipment is a jaw crusher, and the screen forming a closed circuit with it is a linear vibrating screen with a screen aperture size of 40mm; the ultrafine crushing equipment is a high-pressure roller mill, and the screen forming a closed circuit with it is a linear vibrating screen with a screen aperture size of 6mm; the coarse wet high-intensity magnetic separator is a Slon coarse vertical ring pulsating high gradient magnetic separator, with a maximum feed particle size of 6mm, a magnetic field strength of 954~1194KA / m, a ring rotation speed of 2~4 rpm, and a pulsation frequency of 40~80 times / minute.

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