A method for fine classification and combined pre-selection of weakly magnetic refractory iron ore

Abstract

The present invention discloses a method for fine classification and combined preselection of weakly magnetic refractory iron ore, wherein the weakly magnetic refractory iron ore with a TFe grade of 25% to 35% and iron minerals mainly consisting of hematite and siderite is crushed to less than 100 mm using a cone crusher in a closed circuit, and then dry-screened into five particle sizes of 0 to 1 mm, 1 to 6 mm, 6 to 15 mm, 15 to 40 mm, and 40 to 100 mm using a multi-layer vibrating screen. The ore is preselected using a fine-grained wet high-intensity magnetic separator, a coarse-grained wet high-intensity magnetic separator, a dry high-intensity magnetic separator, a large-block jig, and a photoelectric intelligent separator, respectively; the preselected concentrates of each particle size are combined as the final preselected concentrate, and the preselected tailings of each particle size are combined as the final preselected tailings. The method of the present invention integrates a variety of different preselection equipment, gives full play to the sorting performance of each equipment, has the advantages of large raw ore selection particle size, preselection of all particle sizes, and good preselection indicators, and can be promoted and applied in weakly magnetic iron mines.

Description

Technical Field

[0001] The present invention belongs to the technical field of beneficiation of weakly magnetic refractory iron ores, and specifically relates to a method for fine classification and combined pre-selection of weakly magnetic refractory iron ores, which is particularly suitable for the separation of single or mixed ores such as hematite, limonite and siderite with a total iron grade between 25% and 35%. Background Art

[0002] Preselection is a crucial operation in the beneficiation of low-grade iron ore. By preselecting and discarding qualified tailings early, not only can the beneficiation grade be improved, but it can also significantly reduce the processing volume of subsequent operations, thereby achieving energy savings and reducing costs. For a long time, a single magnetic separation process has generally been sufficient to achieve satisfactory preselection performance for strongly magnetic minerals. However, for weakly magnetic minerals such as hematite, limonite, and siderite, the separation performance of a single magnetic separation process is significantly inferior to that of strongly magnetic minerals. However, most mines currently still rely solely on dry-type high-intensity magnetic preselection. In recent years, with the development and maturity of wet-type coarse-grained high-intensity magnetic preselection equipment and optoelectronic intelligent preselection equipment, these two new processes have been commercially applied in some weakly magnetic iron mines. Combined with dry-type high-intensity magnetic preselection, these processes have significantly improved separation performance. For example, Chinese invention patent (application number 201910996429.3) discloses a combined preselection and discarding process for complex, intergrowth, and difficult-to-separate iron ores. The process first crushes the co-existing refractory iron ore to 0-50mm, and then screens it into two particle sizes: 0-10mm and 10-50mm. A magnetic pulley is used to pre-select and separate the 10-50mm particle size co-existing refractory iron ore, with the pre-selected concentrate being magnetite and the pre-selected tailings being weakly magnetic iron ore and surrounding rock. An X-ray transmission intelligent pre-selector is then used to separate the 10-50mm particle size weakly magnetic iron ore from the surrounding rock, with the pre-selected concentrate being weakly magnetic iron ore and the pre-selected tailings being surrounding rock. A spiral dry magnetic separator is used to separate magnetite, weakly magnetic iron ore, and surrounding rock from the 0-10mm particle size co-existing refractory iron ore, with the pre-selected concentrate being magnetite and the pre-selected tailings being a mixed tailing of weakly magnetic iron ore and surrounding rock. A spiral dry magnetic separator is used to separate the 0-10mm particle size pre-selected tailings from weakly magnetic iron ore and surrounding rock. Although this patent utilizes a combined pre-selection process, it still has the following shortcomings: (1) Its maximum feed particle size is only 50 mm, which fails to fully realize the concept of "throwing as early as possible"; (2) The photoelectric intelligent pre-selection equipment uses a single layer of cloth. If it is used to process ores below 40 mm, its single-machine processing capacity will be severely reduced; (3) For fine particles below 6 mm, due to the fine particle size and easy agglomeration, it is more appropriate to use wet strong magnetic pre-selection.

[0003] In view of the above reasons, the present invention first finely classifies the weakly magnetic iron ore, and then adopts different pre-selection processes according to the characteristics of different particle sizes, thereby finally achieving refined and efficient pre-selection of the weakly magnetic iron ore. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for fine classification and combined pre-selection of weakly magnetic and difficult-to-select iron ores to address the technical difficulties in the prior art, such as the inability to pre-select and discard tailings of weakly magnetic iron ores, poor sorting effect for coarse particles of 50 mm and fine particles below 6 mm, and low processing capacity.

[0005] To achieve the above-mentioned object of the present invention, a method for fine classification and combined pre-selection of weakly magnetic refractory iron ore is provided, which is implemented by the following steps:

[0006] S1 uses a cone crusher to crush the weakly magnetic refractory iron ore with a TFe content of 25% to 35% and mainly hematite and siderite into particles smaller than 100 mm. It is then dry-screened using a multi-layer vibrating screen to five particle sizes: 0-1 mm, 1-6 mm, 6-15 mm, 15-40 mm, and 40-100 mm.

[0007] S2 uses different pre-selection equipment to pre-select and discard the tailings for different particle sizes in step S1, among which the 0-1mm particle size uses a fine-grained wet high-intensity magnetic separator for pre-selection and discarding, the 1-6mm particle size uses a coarse-grained wet high-intensity magnetic separator for pre-selection and discarding, the 6-15mm particle size uses a dry high-intensity magnetic separator for pre-selection and discarding, the 15-40mm particle size uses a large-block jig for pre-selection and discarding, and the 40-100mm particle size uses a photoelectric intelligent separator for pre-selection; the pre-selected concentrates of each particle size are combined as the final pre-selected concentrate, and the pre-selected tailings of each particle size are combined as the final pre-selected tailings.

[0008] Preferably, the mesh sizes of the multi-layer vibrating screen in step S1 are 100 mm, 40 mm, 15 mm, 6 mm and 1 mm from top to bottom respectively.

[0009] Preferably, in step S2, the fine-grained wet high-intensity magnetic separator is a Slon fine-grained vertical ring pulsating high-gradient magnetic separator, with a maximum feed particle size of 2 mm, a magnetic field strength of 954-1194 KA / m, a rotating ring speed of 2-4 revolutions / minute, and a pulsation frequency of 40-80 times / minute.

[0010] Furthermore, in step S2, the coarse-grained wet high-intensity magnetic separator is a Slon coarse-grained vertical ring pulsating high-gradient magnetic separator, with a maximum feed particle size of 6 mm, a magnetic field strength of 954-1194 KA / m, a rotating ring speed of 2-4 revolutions per minute, and a pulsation frequency of 40-80 times per minute.

[0011] Furthermore, in step S2, the dry high-intensity magnetic separator is a permanent magnet roller high-intensity magnetic powder ore dry separator, the maximum feed particle size is 20 mm, the magnetic field strength on the drum surface is 12000 Oe, and the drum inverter frequency is 28 to 32 Hz.

[0012] Furthermore, in step S2, the large block jig machine is a diaphragm type large block jig machine, the jig stroke frequency is 130 to 150 times / min, and the jig stroke is 90 to 110 mm.

[0013] Furthermore, in step S2, the photoelectric intelligent sorting machine is an XNDT-104 fully automatic intelligent online sorting machine with a belt width of 1.6 m and a belt speed of 3 to 4 m / s;

[0014] In addition, the photoelectric intelligent sorting machine can also adopt a HOT intelligent X-ray sorting machine.

[0015] Compared with the prior art, the method of fine classification and combined pre-selection of weakly magnetic refractory iron ore of the present invention has the following beneficial effects:

[0016] (1) The method of the present invention accurately divides weakly magnetic refractory iron ore into five particle sizes of 0-1mm, 1-6mm, 6-15mm, 15-40mm and 40-100mm. The five particle sizes are respectively separated by different separation equipment and different separation methods, wherein: 0-1mm is separated by Slon fine-grain vertical ring pulsating high gradient magnetic separator, 1-6mm is separated by Slon coarse-grain vertical ring pulsating high gradient magnetic separator, 6-15mm is separated by permanent magnet roller strong magnetic powder ore dry separator, 15-40mm is separated by diaphragm large block jig, and 40-100mm is separated by photoelectric intelligent separator. The method organically integrates multiple pre-selection methods (magnetic separation, gravity separation and photoelectric separation) to achieve full-size effective pre-selection of weakly magnetic iron ore under wide size (0-100mm) conditions, solves the problem of narrow effective pre-selection size of traditional single pre-selection method, and greatly improves the separation accuracy.

[0017] (2) The method of the present invention adopts different pre-selection methods according to the characteristics of ores of different particle sizes, which can give full play to the performance of various pre-selection equipment and effectively improve the sorting effect. For example, the present invention adopts photoelectric intelligent pre-selection for large ores of 40-100 mm, which solves the problem that if strong magnetic pre-selection is used for this particle size, the centrifugal force on the mineral is much greater than the magnetic force, resulting in a significantly low metal recovery rate. At the same time, since photoelectric intelligent pre-selection requires a single layer of material, the photoelectric intelligent pre-selection of large ores of 40-100 mm also effectively improves the hourly processing capacity of photoelectric intelligent pre-selection; for example, for the fine particle size of 0-6 mm, due to its fine particle size and easy agglomeration, the effect of dry strong magnetic pre-selection is very poor. Therefore, the present invention adopts wet strong magnetic pre-selection for it, and at the same time subdivides it into two particle sizes of 0-1 mm and 1-6 mm for pre-selection, further improving the iron recovery rate of the fine particle size.

[0018] (3) Compared with the traditional single preselection process, the method of the present invention has the advantages of large selected particle size, wide particle size, large tailing amount, low energy consumption, etc., and the tailing yield is as high as more than 22%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a process flow chart showing the principle of a method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to the present invention.

[0020] Figure 2 The figure is a flow chart of an embodiment of a method for fine classification and combined preselection of weakly magnetic refractory iron ore according to the present invention. DETAILED DESCRIPTION

[0021] To further illustrate the present invention, a method for fine classification and combined pre-selection of weakly magnetic refractory iron ore is described in detail below with reference to the accompanying drawings and examples. However, the present invention is not limited to the examples.

[0022] The ore sample used in this example was a weakly magnetic iron ore from an iron mine in western China. The ore's iron minerals are primarily hematite and siderite, which together account for over 95% of the total iron minerals, making it a typical weakly magnetic, refractory iron ore. The results of the multi-element analysis and iron phase analysis of the ore are shown in Tables 1 and 2.

[0023] Table 1 Multi-element analysis results of raw ore (%)

[0024] 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 content 0.881 0.047 0.040 0.005 0.195 0.008 0.003 12.92

[0025] Table 2 Results of iron phase analysis of raw ore (%)

[0026] Name of Prime Minister magnetite hematite siderite Iron silicate pyrite Pyrrhotite total Iron content 0.50 21.41 9.68 0.52 0.31 0.0022 32.42 Iron distribution rate 1.54 66.04 29.85 1.60 0.96 0.01 100.00

[0027] The specific implementation steps are as follows:

[0028] (1) The ore is crushed to less than 100 mm in a closed-circuit cone crusher, and then dry-screened using a multi-layer vibrating screen. The sieve hole sizes of the multi-layer vibrating screen are 100 mm, 40 mm, 15 mm, 6 mm, and 1 mm from top to bottom. After screening, five particle sizes of 0-1 mm, 1-6 mm, 6-15 mm, 15-40 mm, and 40-100 mm are obtained.

[0029] (2) The different particle sizes obtained in step (1) are preselected separately using different preselection equipment, wherein the 0-1 mm particle size is preselected by fine wet strong magnetic separation, the fine wet strong magnetic separation equipment is a Slon fine particle vertical ring pulsating high gradient magnetic separator, the maximum feed particle size is 2 mm, the magnetic field strength is 1114 KA / m, the rotating ring speed is 3 rev / min, and the pulsation frequency is 60 times / min. The 1-6 mm particle size is preselected by coarse wet strong magnetic separation, the coarse wet strong magnetic separation equipment is a Slon coarse particle vertical ring pulsating high gradient magnetic separator, the maximum feed particle size is 6 mm, the magnetic field strength is 1114 KA / m, the rotating ring speed is 3 rev / min, and the pulsation frequency is 60 times / min. The 6-15mm particle size is preselected using dry high-intensity magnetic separation equipment, a permanent magnet roller-type high-intensity magnetic fine ore dry separator with a maximum feed size of 20mm, a drum surface magnetic field strength of 12,000 Oe, and a drum inverter frequency of 30 Hz. The 15-40mm particle size is preselected using a laboratory-type diaphragm bulk jig with a jig rate of 135 strokes / min and a jig stroke of 105mm. The 40-100mm particle size is preselected using an XNDT-104 intelligent preselector with a belt width of 1.6m and a belt speed of 3.5m / s. Preselected concentrates from each particle size are combined as the final preselected concentrate, and preselected tailings from each particle size are combined as the final preselected tailings.

[0030] After being processed by the above process, the weakly magnetic iron ore with an iron grade of 32.60% can obtain a pre-selected concentrate with an iron grade of 37.69%, an iron recovery rate of 89.62%, a tailings yield of 22.50%, and a tailings grade of 15.04%, which are good indicators.

[0031] The above are merely preferred embodiments of the method of the present invention, but the scope of protection of the method of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the method of the present invention should be based on the scope of protection defined in the claims.

Claims

1. A method for fine classification and combined pre-selection of weakly magnetic refractory iron ore, characterized in that Use the following steps to implement: S1 uses a cone crusher to crush the weakly magnetic refractory iron ore with a TFe content of 25% to 35% and mainly hematite and siderite into particles smaller than 100 mm. It is then dry-screened using a multi-layer vibrating screen to five particle sizes: 0-1 mm, 1-6 mm, 6-15 mm, 15-40 mm, and 40-100 mm. S2 uses different pre-selection equipment to pre-select and discard the tailings for different particle sizes in step S1, among which the 0-1mm particle size uses a fine-grained wet high-intensity magnetic separator for pre-selection and discarding, the 1-6mm particle size uses a coarse-grained wet high-intensity magnetic separator for pre-selection and discarding, the 6-15mm particle size uses a dry high-intensity magnetic separator for pre-selection and discarding, the 15-40mm particle size uses a large-block jig for pre-selection and discarding, and the 40-100mm particle size uses a photoelectric intelligent separator for pre-selection; the pre-selected concentrates of each particle size are combined as the final pre-selected concentrate, and the pre-selected tailings of each particle size are combined as the final pre-selected tailings.

2. The method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to claim 1, characterized in that: The mesh sizes of the multi-layer vibrating screen in step S1 are 100 mm, 40 mm, 15 mm, 6 mm, and 1 mm from top to bottom.

3. The method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to claim 1, characterized in that: In step S2, the fine-grained wet high-intensity magnetic separator is a Slon fine-grained vertical ring pulsating high-gradient magnetic separator, with a maximum feed particle size of 2 mm, a magnetic field strength of 954-1194 KA / m, a rotating ring speed of 2-4 rpm, and a pulsation frequency of 40-80 times / min.

4. The method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to claim 1, characterized in that: In step S2, the coarse-grained wet high-intensity magnetic separator is a Slon coarse-grained vertical ring pulsating high-gradient magnetic separator with a maximum feed particle size of 6 mm, a magnetic field strength of 954-1194 KA / m, a rotating ring speed of 2-4 rpm, and a pulsating frequency of 40-80 times / min.

5. The method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to claim 1, characterized in that: In step S2, the dry-type high-intensity magnetic separator is a permanent magnet roller-type high-intensity magnetic powder ore dry separator, with a maximum feed particle size of 20 mm, a drum surface magnetic field strength of 12000 Oe, and a drum inverter frequency of 28 to 32 Hz.

6. The method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to claim 1, characterized in that: In step S2, the large block jig machine is a diaphragm type large block jig machine, the jig stroke frequency is 130 to 150 times / min, and the jig stroke is 90 to 110 mm.

7. The method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to claim 1, characterized in that: In step S2, the photoelectric intelligent sorting machine is an XNDT-104 fully automatic intelligent online sorting machine with a belt width of 1.6 m and a belt speed of 3 to 4 m / s.

8. The method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to claim 1, characterized in that: In step S2, the photoelectric intelligent sorting machine is a HOT intelligent X-ray sorting machine.

9. The method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to claim 2, characterized in that: In step S2, the fine-grained wet high-intensity magnetic separator is a Slon fine-grained vertical ring pulsating high-gradient magnetic separator, with a maximum feed particle size of 2 mm, a magnetic field strength of 954-1194 KA / m, a rotating ring speed of 2-4 rpm, and a pulsating frequency of 40-80 times / min; the coarse-grained wet high-intensity magnetic separator is a Slon coarse-grained vertical ring pulsating high-gradient magnetic separator, with a maximum feed particle size of 6 mm, a magnetic field strength of 954-1194 KA / m, a rotating ring speed of 2-4 rpm, and a pulsating frequency of 40-8 0 times / minute; the dry-type strong magnetic separator is a permanent magnet roller-type strong magnetic powder ore dry separator with a maximum feed particle size of 20mm, a drum surface magnetic field strength of 12000Oe, and a drum inverter frequency of 28-32HZ; the large-block jig is a diaphragm-type large-block jig with a jig stroke of 130-150 times / min and a jig stroke of 90-110mm; the photoelectric intelligent sorting machine is an XNDT-104 fully automatic intelligent online sorting machine with a belt width of 1.6m and a belt speed of 3-4m / s.

10. The method for fine classification and combined pre-selection of weakly magnetic refractory iron ore according to claim 2, characterized in that: In step S2, the fine-grained wet high-intensity magnetic separator is a Slon fine-grained vertical ring pulsating high-gradient magnetic separator, with a maximum feed particle size of 2 mm, a magnetic field strength of 954-1194 KA / m, a rotating ring speed of 2-4 rpm, and a pulsating frequency of 40-80 times / min; the coarse-grained wet high-intensity magnetic separator is a Slon coarse-grained vertical ring pulsating high-gradient magnetic separator, with a maximum feed particle size of 6 mm and a magnetic field strength of 954-1194 K A / m, the rotating ring speed is 2-4 rpm, and the pulsation frequency is 40-80 times / min; the dry-type strong magnetic separator is a permanent magnet roller-type strong magnetic powder ore dry separator, with a maximum feed particle size of 20mm, a drum surface magnetic field intensity of 12000Oe, and a drum inverter frequency of 28-32HZ; the large block jig is a diaphragm-type large block jig, with a jig stroke of 130-150 times / min and a jig stroke of 90-110mm; The photoelectric intelligent sorting machine mentioned above is a HOT intelligent X-ray sorting machine.

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