Method for combined pre-concentration and waste discarding of strong and weak magnetic mixed iron ore

Abstract

The invention discloses a combined pre-concentration and waste discarding method for strong and weak magnetic mixed iron ore, which comprises the following steps of: crushing the strong and weak magnetic iron ore to below 50mm in a closed-circuit manner, and screening the strong and weak magnetic iron ore into three particle fractions of 50-20mm, 20-2mm and 2-0mm; an electromagnetic dry separator and a photoelectric intelligent dry separator are adopted for conducting pre-selection and waste throwing treatment on the iron ore with the particle size of 50-20 mm, and weak magnetic dry separation block concentrate and pre-selected concentrate I are obtained; a permanent magnet drum type dry magnetic separator and a permanent magnet roller type strong magnetic dry separator are adopted for conducting pre-selection and waste throwing treatment on the iron ore with the particle size of 20-2 mm, and pre-selected concentrate II is obtained; and a wet electromagnetic drum type magnetic separator and a pulsating high-gradient magnetic separator are adopted for conducting pre-selection and waste throwing treatment on the iron ore with the particle size of 2-0 mm, and pre-selected concentrate III is obtained. According to the method, multiple pre-selection waste throwing methods are adopted in a combined mode, the separation performance of all equipment is fully played, a large number of gangue entering the separation process is reduced, the raw ore separation quality and the system processing capacity are effectively improved, the production cost is reduced, and the method has wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of mineral processing, and specifically relates to a method for the combined pre-selection and discarding of strong and weak magnetic mixed iron ores, which is particularly suitable for the efficient pre-selection of strong and weak magnetic mixed iron ores with a TFe grade between 35% and 45% and whose iron minerals are mainly magnetite, phantom (semi-pseudo-phantom) hematite, hematite and siderite. Background Art

[0002] my country has large iron ore reserves, ranking fourth in the world. However, my country's iron ore deposits are diverse in genesis and complex in ore type. Iron ore is "poor, fine, mixed and scattered", with more poor ores and fewer rich ores. The average iron grade is 32%, 11 percentage points lower than the world average. 97% of the iron ore needs to be processed, especially complex and difficult to select iron oxide ores, including hematite, specularite, limonite, siderite, etc. The beneficiation technology is difficult and the processing cost is high. A large amount of magnetite and iron oxide ore coexist in complex, making the beneficiation technology more difficult, the process more complicated and the processing cost high.

[0003] "Throw away what can be thrown away early, collect what can be collected early" is one of the basic principles of mineral processing to achieve energy-saving and efficient production. Pre-selection is an important operation to improve the grade of iron ore to be selected. By discarding qualified tailings in advance through pre-selection, not only can the grade of selected ore be improved, but also the processing volume of subsequent operations can be greatly reduced, thus achieving the purpose of energy saving and consumption reduction.

[0004] For example, a Chinese invention patent (application number 201611194228.4) discloses a dry pre-separation method for strongly magnetic-weakly magnetic mixed iron ore, which feeds the strongly magnetic-weakly magnetic mixed iron ore into an upward suction combined dry separator, obtains strongly magnetic minerals by the upward suction combined dry separation operation, and then separates weakly magnetic ore and gangue by high magnetic force and strong magnetic separation of magnetic tailings. However, this method is suitable for dry separation of mixed iron ore with a particle size of ≤25mm after fine crushing or high-pressure roller grinding.

[0005] In addition, the Chinese invention patent (application number 201910996347.9) discloses a combined pre-selection and discarding process for weakly magnetic and difficult-to-select iron ore, which performs particle size classification on 0-100mm weakly magnetic and difficult-to-select iron ore, which is divided into four particle size ranges: 0-5mm, 5-15mm, 15-50mm, and 50-100mm; a fully sealed spiral dry magnetic separator is used for three-stage pre-selection and discarding of 0-5mm weakly magnetic and difficult-to-select iron ore; a strong magnetic induction roller is used for two-stage pre-selection and discarding of 5-15mm weakly magnetic and difficult-to-select iron ore; and X-ray transmission intelligent separation is used for one-stage pre-selection and discarding of 15-50mm and 50-100mm weakly magnetic and difficult-to-select iron ore, respectively. However, this method is only suitable for pre-selection and discarding of weakly magnetic and difficult-to-select iron ore, but is difficult to handle mixed iron ore with strong and weak magnetism. Moreover, for fine particles below 2 mm, due to their fine particle size and easy agglomeration, wet magnetic pre-selection is more suitable to improve the separation accuracy. Summary of the invention

[0006] The purpose of the present invention is to provide a method for the combined pre-selection and discarding of strong and weak magnetic mixed iron ores, which can discard the gangue in the ore to the maximum extent through the classification and fine pre-selection of different types of equipment, reduce the large amount of gangue minerals entering the separation process, reduce the mineral processing cost, improve the mineral processing index, and stabilize the mineral processing production process.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme: a method for pre-selecting and discarding mixed iron ores with strong and weak magnetic properties, comprising the following steps:

[0008] S1. The refractory iron ore with TFe content between 35% and 45% and iron minerals mainly composed of magnetite, pseudo-(semi-pseudo-)hematite, hematite and siderite is crushed in a closed circuit to a size below 50 mm, and then classified by a linear vibrating screen to obtain three particle sizes of 50-20 mm, 20-2 mm and 2-0 mm;

[0009] S2. The three particle sizes of 50-20 mm, 20-2 mm, and 2-0 mm obtained in step S1 are graded and pre-selected by different pre-selection equipment, wherein the 50-20 mm particle size is pre-selected by a weak magnetic dry separator to obtain a weak magnetic dry separator concentrate with a TFe grade greater than 54% and a dry weak magnetic pre-selected tailings, and the dry weak magnetic pre-selected tailings are pre-selected by a photoelectric intelligent dry separator to obtain a photoelectric intelligent pre-selected concentrate and discard the photoelectric intelligent pre-selected tailings;

[0010] S3, using a medium magnetic dry separator to obtain a dry medium magnetic pre-selected concentrate and a dry medium magnetic pre-selected tailings for the 20-2 mm particle size obtained in step S1, and using a roller-type strong magnetic dry separator to obtain a strong magnetic dry pre-selected concentrate for the dry medium magnetic pre-selected tailings, and throwing out the strong magnetic dry pre-selected tailings;

[0011] S4, using a weak magnetic wet separator to obtain a wet weak magnetic pre-selected concentrate and a wet weak magnetic pre-selected tailings from the 2-0 mm particle size obtained in step S1, and using a vertical ring high gradient strong magnetic wet separator to obtain a vertical ring strong magnetic wet selection pre-selected concentrate from the wet weak magnetic pre-selected tailings, and throwing out the vertical ring strong magnetic wet selection pre-selected tailings;

[0012] S5. Combine the photoelectric intelligent pre-selection concentrate obtained in step S2, the dry medium magnetic pre-selection concentrate obtained in step S3, the roller strong magnetic dry selection pre-selection concentrate, the wet weak magnetic pre-selection concentrate and the vertical ring strong magnetic wet selection pre-selection concentrate obtained in step S4 as the final pre-selection concentrate; combine the photoelectric intelligent pre-selection tailings in step S2, the roller strong magnetic dry selection pre-selection tailings in step S3 and the vertical ring strong magnetic wet selection pre-selection tailings in step S4 as the final pre-selection tailings.

[0013] Furthermore, in step S1, the secondary crushing equipment adopts two-stage crushing, the first stage adopts PYB-2200 multi-cylinder hydraulic cone crusher, and the second stage adopts MH-500 multi-cylinder hydraulic cone crusher and circular vibrating screen equipment to form a closed circuit, and the screen hole size is 50 mm.

[0014] Furthermore, in step S2, the weak magnetic dry separator is a Φ500×800 electromagnetic dry separator, with a magnetic field strength of 55.6 to 87.5 kA / m, a feed line speed of 1.92 to 3.62 m / s, and a separation plate spacing of 35 to 45 cm.

[0015] Furthermore, in step S2, the photoelectric intelligent dry sorting machine is a 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.

[0016] Furthermore, in step S3, the medium magnetic dry separator is a Φ350 permanent magnetic drum dry magnetic separator, with a magnetic field strength of 238 to 279 kA / m, a belt speed of 1.25 to 1.67 m / s, and a separation plate spacing of 15 to 25 cm.

[0017] Furthermore, in step S3, the high-intensity magnetic dry separator is a YCG-350 permanent magnet roller high-intensity magnetic dry separator, with a magnetic field strength of 800 to 1035 kA / m, a belt speed of 1.25 to 1.67 m / s, and a separation plate spacing of 20 to 30 cm.

[0018] Furthermore, in step S4, the weak magnetic wet separator is a Φ400×300 wet electromagnetic drum magnetic separator with a magnetic field strength of 111 to 159 kA / m.

[0019] Furthermore, in step S4, the vertical ring strong magnetic wet separator is a Slon 750 pulsating high gradient magnetic separator, with a magnetic field strength of 60 to 159 kA / m, a magnetic medium of 2 to 6 mm rod medium, a rotating ring speed of 0 to 5 r / min, a pulsating stroke of 150 to 250 times / min, and a flushing water volume of 4 to 8 L / min.

[0020] Furthermore, in step S1, the weak magnetic dry selected lump concentrate is directly melted and smelted as the blast furnace rich ore to improve the permeability and smelting efficiency of the blast furnace, and the pre-selected concentrate enters the next grinding operation.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The mixed iron ore combined pre-selection and discarding method of the present invention is to accurately classify the raw ore first, and then use different pre-selection methods and pre-selection equipment in combination to achieve efficient classification pre-selection and discarding of strong and weak magnetic mixed iron ores under the condition of full particle size (0-50mm), wherein the 50-20mm particle size adopts an electromagnetic dry separator + a photoelectric intelligent dry separator, the 20-2mm particle size adopts a permanent magnetic drum dry magnetic separator + a permanent magnetic roller strong magnetic dry separator, and the 2-0mm particle size adopts a wet electromagnetic drum magnetic separator + a vertical ring pulsating high gradient magnetic separator. A variety of pre-selection methods (dry magnetic separation, wet magnetic separation, photoelectric intelligent separation) are used in combination to achieve effective and accurate pre-selection of strong and weak magnetic mixed iron ores under the condition of wide particle size (0-50mm).

[0023] (2) The mixed iron ore joint pre-selection and waste disposal 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 first uses weak magnetic separation to pre-separate part of the high-grade magnetite block ore of 50-20 mm large ore as blast furnace rich ore for direct melting and smelting, and uses photoelectric intelligent pre-selection to separate weak magnetic iron ore from gangue in the weak magnetic separation tailings, fully implementing the concept of "early collection when possible and early disposal when possible", and discarding large waste rocks early.

[0024] (3) The present invention uses different types of equipment for classification and fine pre-selection to maximize the removal of gangue in the ore, and pre-separates part of the high-grade magnetite ore as blast furnace rich ore for direct melting and smelting, thereby reducing the amount of ore required for subsequent crushing and grinding, and reducing energy consumption and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a process flow chart showing the principle of a method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores.

[0026] Figure 2 The present invention is a method for the combined pre-selection and discarding of strong and weak magnetic mixed iron ores. DETAILED DESCRIPTION

[0027] To further describe the present invention, a method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores is further described in detail below in conjunction with the accompanying drawings and implementation examples. However, the present invention is not limited to the implementation examples.

[0028] Embodiment: The ore samples used in this embodiment are strong and weak magnetic mixed iron ore from a large iron mine in eastern China. The iron ore of the ore is mainly magnetite, pseudo (semi-pseudo) hematite, hematite and siderite. The results of multi-element analysis and iron phase analysis of the ore are shown in Tables 1 and 2.

[0029] Table 1 Results of multi-element analysis of raw ore (%)

[0030] Test items TFe FeO <![CDATA[SiO 2 ]]> <![CDATA[Al 2 THE 3 ]]> CaO MgO S content(%) 37.79 16.40 16.86 3.19 7.93 2.19 1.00 Test items P <![CDATA[K 2 The]]> <![CDATA[Na 2 The]]> MnO <![CDATA[TiO 2 ]]> <![CDATA[V 2 O 5 > Burning content(%) 0.31 0.469 0.427 0.336 0.238 0.146 10.67

[0031] Table 2 Analysis results of iron phase of raw ore (%)

[0032] Phase Name magnetite Hematite Siderite Iron silicate Pyrite total Contains content 17.27 13.35 5.18 1.11 1.02 37.93 Iron distribution rate 45.52 35.21 13.67 2.92 2.68 100.00

[0033] Depend on Figure 1 The process flow chart of the invention shows a method for pre-selecting and discarding strong and weak magnetic mixed iron ores. Figure 2 It can be seen that the specific implementation steps adopted in the implementation case of the method for combined pre-selection and discarding of strong and weak magnetic mixed iron ore of the present invention are as follows:

[0034] (1) The iron ore with strong and weak magnetic properties and a TFe grade of 37.79% and mainly composed of magnetite, pseudo-(semi-pseudo-)hematite, hematite and siderite is crushed in a closed circuit to a size of less than 50 mm, and then classified by a linear vibrating screen to obtain three particle sizes of 50-20 mm, 20-2 mm and 2-0 mm;

[0035] (2) The three particle sizes of 50-20 mm, 20-2 mm, and 2-0 mm obtained in step (1) are separately graded and pre-selected by different pre-selection equipment, wherein the 50-20 mm particle size is subjected to weak magnetic dry selection to obtain weak magnetic dry selection block concentrate with a TFe grade greater than 54% and dry weak magnetic pre-selection tailings, and the dry weak magnetic pre-selection tailings are pre-selected by a photoelectric intelligent dry separator to obtain a photoelectric intelligent pre-selection concentrate and discard the photoelectric intelligent pre-selection tailings;

[0036] (3) The 20-2 mm particle size obtained in step (1) is subjected to medium magnetic dry separation to obtain dry medium magnetic pre-separation concentrate and dry medium magnetic pre-separation tailings, and the dry medium magnetic pre-separation tailings are subjected to roller-type strong magnetic dry separation to obtain roller-type strong magnetic dry separation pre-separation concentrate and throw-out roller-type strong magnetic dry separation pre-separation tailings;

[0037] (4) the 2-0 mm particle size obtained in step (1) is subjected to weak magnetic wet separation to obtain wet weak magnetic pre-separation concentrate and wet weak magnetic pre-separation tailings, and the wet weak magnetic pre-separation tailings are subjected to vertical ring high gradient strong magnetic wet separation to obtain vertical ring strong magnetic wet separation pre-separation concentrate, and the vertical ring strong magnetic wet separation pre-separation tailings are thrown out;

[0038] (5) The photoelectric intelligent pre-selection concentrate obtained in step (2), the dry medium magnetic pre-selection concentrate obtained in step (3), the roller strong magnetic dry separation pre-selection concentrate, the wet weak magnetic pre-selection concentrate, and the vertical ring strong magnetic wet separation pre-selection concentrate obtained in step (4) are combined as the final pre-selection concentrate, and the photoelectric intelligent pre-selection tailings of step (2), the roller strong magnetic dry separation pre-selection tailings of step (3), and the vertical ring strong magnetic wet separation pre-selection tailings of step (4) are combined as the final pre-selection tailings.

[0039] In the step (1), the secondary crushing equipment adopts two-stage crushing, the first stage adopts PYB-2200 multi-cylinder hydraulic cone crusher, and the second stage adopts MH-500 multi-cylinder hydraulic cone crusher and circular vibrating screen equipment to form a closed circuit, and the screen hole size is 50mm.

[0040] The weak magnetic dry separator in step (2) is a Φ500×800 electromagnetic dry separator, with a magnetic field strength of 71.6 kA / m, a feed line speed of 2.63 m / s, and a separation plate spacing of 38 cm. The photoelectric intelligent dry separator is an XNDT-104 fully automatic intelligent online separator, with a belt width of 1.6 m and a belt speed of 3.5 m / s.

[0041] The medium magnetic dry separator in step (3) is a Φ350 permanent magnetic drum dry magnetic separator, with a magnetic field strength of 254 kA / m, a belt speed of 1.57 m / s, and a separation partition spacing of 20 cm. The roller-type strong magnetic dry separator is a YCG-350 permanent magnetic roller-type strong magnetic dry separator, with a magnetic field strength of 955 kA / m, a belt speed of 1.57 m / s, and a separation partition spacing of 27 cm.

[0042] The weak magnetic wet separator in step (4) is a Φ400×300 wet electromagnetic drum magnetic separator with a magnetic field strength of 143 kA / m. The vertical ring high gradient strong magnetic wet separator is a Slon 750 pulsating high gradient magnetic separator with a magnetic field strength of 80 kA / m, a magnetic medium of 4 mm rod medium, a rotating ring speed of 2 r / min, a pulsating stroke of 200 times / min, and a flushing water volume of 6 L / min.

[0043] After the above process treatment, the strong and weak magnetic mixed iron ore with an original iron grade of 37.79% can obtain a lump concentrate with a grade of 54.38% in advance. By discarding qualified tailings with a yield of 15.94% and an iron grade of 15.10%, the pre-selected concentrate has an iron grade of 42.41%, which is more than 4 percentage points higher than the original ore, and the iron recovery rate of the concentrate is 86.23%.

[0044] The above is only a preferred implementation case of the mixed iron ore combined preselection of the present invention, but the protection scope of the mixed iron ore combined preselection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the mixed iron ore combined preselection process of the present invention should be based on the protection scope defined by the claims.

Claims

1. A method for pre-selecting and discarding mixed iron ores with strong and weak magnetic properties, characterized in that: The method comprises the following steps: S1. The refractory iron ore with TFe content between 35% and 45% and iron minerals mainly composed of magnetite, pseudo-(semi-pseudo-)hematite, hematite and siderite is crushed in a closed circuit to a size below 50 mm, and then classified by a linear vibrating screen to obtain three particle sizes of 50-20 mm, 20-2 mm and 2-0 mm; S2. The three particle sizes of 50-20 mm, 20-2 mm, and 2-0 mm obtained in step S1 are graded and pre-selected by different pre-selection equipment, wherein the 50-20 mm particle size is pre-selected by a weak magnetic dry separator to obtain a weak magnetic dry separator concentrate with a TFe grade greater than 54% and a dry weak magnetic pre-selected tailings, and the dry weak magnetic pre-selected tailings are pre-selected by a photoelectric intelligent dry separator to obtain a photoelectric intelligent pre-selected concentrate and discard the photoelectric intelligent pre-selected tailings; S3, using a medium magnetic dry separator to obtain a dry medium magnetic pre-selected concentrate and a dry medium magnetic pre-selected tailings for the 20-2 mm particle size obtained in step S1, and using a roller-type strong magnetic dry separator to obtain a strong magnetic dry pre-selected concentrate for the dry medium magnetic pre-selected tailings, and throwing out the strong magnetic dry pre-selected tailings; S4, using a weak magnetic wet separator to obtain a wet weak magnetic pre-selected concentrate and a wet weak magnetic pre-selected tailings from the 2-0 mm particle size obtained in step S1, and using a vertical ring high gradient strong magnetic wet separator to obtain a vertical ring strong magnetic wet selection pre-selected concentrate from the wet weak magnetic pre-selected tailings, and throwing out the vertical ring strong magnetic wet selection pre-selected tailings; S5. Combine the photoelectric intelligent pre-selection concentrate obtained in step S2, the dry medium magnetic pre-selection concentrate obtained in step S3, the roller strong magnetic dry selection pre-selection concentrate, the wet weak magnetic pre-selection concentrate and the vertical ring strong magnetic wet selection pre-selection concentrate obtained in step S4 as the final pre-selection concentrate; combine the photoelectric intelligent pre-selection tailings in step S2, the roller strong magnetic dry selection pre-selection tailings in step S3 and the vertical ring strong magnetic wet selection pre-selection tailings in step S4 as the final pre-selection tailings.

2. The method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores according to claim 1, characterized in that: In step S1, the secondary crushing equipment adopts two-stage crushing. The first stage adopts PYB-2200 multi-cylinder hydraulic cone crusher, and the second stage adopts MH-500 multi-cylinder hydraulic cone crusher and circular vibrating screen equipment to form a closed circuit, and the screen hole size is 50mm.

3. The method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores according to claim 1, characterized in that: In step S2, the weak magnetic dry separator is a Φ500×800 electromagnetic dry separator with a magnetic field strength of 55.6-87.5 kA / m, a feed line speed of 1.92-3.62 m / s, and a separation plate spacing of 35-45 cm.

4. The method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores according to claim 1, characterized in that: In step S2, the photoelectric intelligent dry sorting machine is a 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.

5. The method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores according to claim 1, characterized in that: In step S3, the medium magnetic dry separator is a Φ350 permanent magnetic drum dry magnetic separator, with a magnetic field strength of 238 to 279 kA / m, a belt speed of 1.25 to 1.67 m / s, and a separation partition spacing of 15 to 25 cm.

6. The method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores according to claim 1, characterized in that: In step S3, the roller-type high-intensity magnetic dry separator is a YCG-350 permanent magnet roller-type high-intensity magnetic dry separator, with a magnetic field strength of 800 to 1035 kA / m, a belt speed of 1.25 to 1.67 m / s, and a separation partition spacing of 20 to 30 cm.

7. The method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores according to claim 1, characterized in that: In step S4, the weak magnetic wet separator is a Φ400×300 wet electromagnetic drum magnetic separator with a magnetic field strength of 111 to 159 kA / m.

8. The method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores according to claim 1, characterized in that: In step S4, the vertical ring strong magnetic wet separator is a Slon 750 pulsating high gradient magnetic separator with a magnetic field strength of 60-159 kA / m, a magnetic medium of 2-6 mm rod medium, a rotating ring speed of 0-5 r / min, a pulsating stroke of 150-250 times / min, and a flushing water volume of 4-8 L / min.

9. The method for combined pre-selection and discarding of strong and weak magnetic mixed iron ores according to claim 1, characterized in that: In step S1, the weak magnetic dry-selected lump concentrate is directly melted and smelted as the blast furnace rich ore to improve the permeability and smelting efficiency of the blast furnace. The pre-selected concentrate enters the next grinding operation, and qualified iron ore concentrate is obtained through grinding-sulfur floating-weak magnetic-strong magnetic separation.

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