Iron-extracting and silicon-reducing magnetic separation method for mixed iron ore rough concentrate

Abstract

The invention relates to an iron-extracting and silicon-reducing magnetic separation method for mixed iron ore rough concentrate. The method comprises the following steps: step 1, optimizing weak magnetic separation concentration; step 2, low-intensity magnetic separation stepped scavenging; step 3, separating coarse tailings from weak magnetic scavenging tailings; step 4, performing one-roughing and one-sweeping strong magnetic separation; 5, regrinding the concentrate subjected to weak magnetic scavenging and the concentrate subjected to strong magnetic scavenging; and step 6, cyclone overflow re-separation. According to the method, a part of low-silicon and high-iron coarse particle iron minerals are recycled in advance from the selected mixed iron ore rough concentrate, gangue minerals dissociated from the iron minerals are removed in advance, the content of SiO2 in the final iron concentrate is reduced through magnetic separation, and the high-grade and high-recovery-rate iron concentrate product is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of mixed iron ore beneficiation, and in particular to a beneficiation method for reducing the SiO2 content in mixed iron ore concentrate by a low-cost magnetic separation method. Background Art

[0002] With the continuous acceleration of my country's industrialization and modernization process, the domestic demand for iron ore resources has increased significantly. Strengthening the efficient development and utilization of domestic complex and difficult-to-select mixed iron ore and improving the self-sufficiency rate of iron ore can alleviate my country's dependence on foreign iron ore to a certain extent. At the same time, it has important practical significance for the sustainable development of iron ore resources.

[0003] my country has relatively rich iron ore resources and large reserves, but most of them are complex and difficult-to-select mixed iron ores, with characteristics such as low iron grade, a wide variety of iron minerals, complex composition, poor resource endowment, and fine embedded grain size. The beneficiation method for recycling mixed iron ore resources such as magnetite, hematite and siderite generally adopts grinding-reverse flotation sulfur flotation-weak magnetic (one rough and one sweep)-strong magnetic (one rough and one sweep) process flow, and then the four concentrates of weak magnetic roughing, weak magnetic sweeping, strong magnetic roughing and strong magnetic sweeping are combined into the final concentrate of the beneficiation plant. However, as the iron ore resources are continuously mined at a deeper depth, the content of magnetic ore decreases, the proportion of hematite (limonite) and siderite increases, the embedded particle size of iron minerals and the impurity SiO2 content in the ore change, resulting in an increase in the SiO2 content in the iron concentrate. Excessive SiO2 content is bound to have an adverse effect on product sales and subsequent smelting process indicators. In order to reduce the SiO2 content in the iron concentrate, most beneficiations adopt the method of increasing the grinding fineness or re-grinding and re-selecting the concentrate or even adding flotation process to desiliconize. All the raw ore (or coarse concentrate) enters the grinding and separation system, which will cause ineffective grinding, increase operating costs, and affect the processing capacity of the grinding and separation system; the re-grinding and re-selection of the concentrate makes the process complicated, the production cost increases, the production operation becomes more difficult, and the principle of early collection and early disposal is not followed. A method for improving the quality and reducing silicon of mixed poor iron magnetic concentrate [CN 106378256 B], by controlling the process parameters of the slurry and the washing magnetic separator, the purpose of destroying magnetic agglomeration is achieved, which has the advantages of simple process and low consumption, but the effect of improving the concentrate grade and reducing the silicon content is not significant; a method for improving the quality and reducing silicon of silicate type hematite rougher concentrate [CN 107442292 B], adding collectors and inhibitors, auxiliary collectors, pH adjusters 5% concentration of H2SO4 stirring positive flotation, good silicon reduction effect, high iron recovery rate, but the flotation process wastewater purification (using sulfuric acid) and reagent costs are high.

[0004] The original separation process is no longer suitable for the current changes in ore properties. Therefore, a mineral processing process and method for reducing the SiO2 content in mixed iron ore concentrate by magnetic separation is invented, so as to realize the early recovery of a part of coarse-grained iron minerals with low silicon and high iron and the early removal of gangue minerals dissociated from iron minerals, greatly reducing the amount of ore entering regrinding and re-selection, and reducing the energy consumption of the concentrator; and reducing the SiO2 content in the final iron concentrate by magnetic separation, obtaining high-grade and high-recovery iron concentrate products, which has demonstration significance and promotion value in similar mixed iron mines. Summary of the invention

[0005] The present invention aims at the problems existing in the prior art and provides a method for improving the quality and reducing the silicon content of mixed iron ore magnetic separation concentrate.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a magnetic separation method for increasing iron content and reducing silicon content in mixed iron ore rough concentrate, comprising the following steps: step 1, optimizing weak magnetic separation concentration; step 2, weak magnetic separation step scavenging; step 3, weak magnetic separation tailings separation; step 4, one rough and one scavenging strong magnetic separation; step 5, weak magnetic separation concentrate, strong magnetic separation concentrate regrinding; step 6, cyclone overflow regrinding.

[0007] Wherein, in the above step 1, the magnetic field strength of the weak magnetic separation is 2000Oe, and the separation concentration is adjusted;

[0008] In the above step 2, the concentrate 1 and tailing 1 are obtained by weak magnetic roughing, and the tailing 1 is subjected to weak magnetic sweeping to obtain the concentrate 2 and tailing 2;

[0009] Wherein, in the above step 3, the tailings 2 in the above step 2 are screened (0.25 mm), the upper part of the screen is material 1, and the lower part of the screen is material 2;

[0010] Wherein, in the above step 4, the undersize material 2 in the above step 3 is subjected to strong magnetic roughing to obtain concentrate 3 and tailings 3, and the tailings 3 is subjected to strong magnetic sweeping to obtain concentrate 4 and tailings 4;

[0011] Among them, in the above step 5, the weak magnetic scavenging concentrate 2 in the above step 3 and the strong magnetic scavenging concentrate 4 in the above step 4 are combined and put into the cyclone for classification, the overflow is material 3, the bottom flow is material 4, material 4 is re-grinded by the tower mill, and the tower mill discharge is put into the cyclone for classification;

[0012] Among them, in the above step six, the overflow material three in the above step five is subjected to weak magnetic reselection to obtain concentrate five and tailings five, and the tailings five is subjected to strong magnetic reselection to obtain concentrate six and tailings six. The concentrate one in the above step two, the concentrate three, the concentrate five and the concentrate six in the above step four are combined into the final concentrate, and the tailings four and the tailings six in the above step four are combined into the total tailings.

[0013] Preferably, in the step 1, the feed sample is a weak magnetic feed slurry of mixed iron ore pre-selected coarse concentrate after grinding and sulfur flotation;

[0014] Preferably, in step 1, the optimal sorting concentration is 14.3%;

[0015] Preferably, in step 2, the magnetic field strength for weak magnetic sweeping is 2000Oe, and the best magnetic field strength for weak magnetic roughing is 450Oe;

[0016] Preferably, in step 3, material 1 can be used as building sand and gravel, and material 2 is subjected to high-intensity magnetic separation;

[0017] Preferably, in step 4, the magnetic field strength is 4500Oe for weak magnetic roughing and 10000Oe for strong magnetic sweeping;

[0018] Preferably, in the step 5, material 4 is re-ground by a tower mill to meet -0.074mm 60%;

[0019] Preferably, in step six, the weak magnetic separation is performed with a magnetic field strength of 2000 Oe, and the strong magnetic separation is performed with a magnetic field strength of 10000 Oe.

[0020] Compared with the prior art, the beneficial effects of the present invention include: under the condition of low weak magnetic field strength (450Oe), by optimizing the weak magnetic separation concentration, coarse-grained iron minerals of qualified quality (low silicon and high iron) can be obtained in advance, thereby achieving early collection; at the same time, the coarse separation process is adopted, so that the dissociated gangue minerals (+0.25mm) can be discarded in advance. This part of the gangue is mainly weakly magnetic iron-containing silicate minerals such as chlorite and garnet, so as to avoid affecting the final concentrate grade after being recovered by subsequent strong magnetic separation, and effectively reduce the subsequent ore concentration amount, thereby achieving early disposal; only the underflow of the weak magnetic scavenging concentrate 2 and the strong magnetic scavenging concentrate 4 is regrinded, so as to avoid ineffective grinding and reduce the energy consumption of the concentrator. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Flow chart of magnetic separation process for iron extraction and silicon reduction of mixed iron ore and iron rough concentrate. DETAILED DESCRIPTION

[0022] In order to deepen the understanding of the present invention, the present embodiment is described in detail below with reference to the accompanying drawings.

[0023] Example: See Figure 1 The present invention provides an embodiment: a magnetic separation method for increasing iron content and reducing silicon content in mixed iron ore and iron coarse concentrate, the method comprising the following steps:

[0024] In the above step 1, under the condition that the weak magnetic separation magnetic field strength is 2000Oe, the weak magnetic separation concentration is adjusted, and the mixed iron ore rough concentrate slurry is subjected to weak magnetic separation, and the optimal weak magnetic separation concentration is determined to be 14.3%, the weak magnetic concentrate w(TFe) is 64.91%, and w(SiO2) is 3.02%;

[0025] In the above step 2, the mixed iron ore rough concentrate slurry is subjected to weak magnetic roughing to obtain concentrate 1 and tailing 1, and tailing 1 is subjected to weak magnetic sweeping to obtain concentrate 2 and tailing 2, the weak magnetic roughing has a magnetic field strength of 450Oe, and the weak magnetic sweeping has a magnetic field strength of 2000Oe;

[0026] In the above step 3, the tailings 2 in the weak magnetic sweeping separation in the above step 2 are separated (0.25 mm), the material on the screen is material 1, which can be used as building sand and gravel, and the material under the screen is material 2, which is subjected to strong magnetic separation;

[0027] In the above step 4, the undersize material 2 in the above step 3 is subjected to strong magnetic roughing to obtain concentrate 3 and tailings 3, and the tailings 3 are subjected to strong magnetic sweeping to obtain concentrate 4 and tailings 4, the magnetic field strength of the weak magnetic roughing is 4500Oe, and the magnetic field strength of the strong magnetic sweeping is 10000Oe;

[0028] In the above step 5, the weak magnetic scavenging concentrate 2 and the strong magnetic scavenging concentrate 4 in the above step 4 are combined and put into the cyclone for classification, the overflow is material 3, which is sent to the weak magnetic re-selection, and the bottom flow is material 4, which is re-grinded in the tower mill to meet -0.074mm 60%, and then returned to the cyclone in a closed circuit;

[0029] Among them, in the above step six, the overflow material three in the above step five is subjected to weak magnetic reselection to obtain concentrate five and tailings five, and the tailings five are subjected to strong magnetic reselection to obtain concentrate six and tailings six, the magnetic field strength of the weak magnetic reselection is 2000Oe, and the magnetic field strength of the strong magnetic reselection is 10000Oe, the concentrate one in the above step two, the concentrate three, the concentrate five and the concentrate six in the above step four are the final concentrate, and the tailings four and the tailings six in the above step four are the total tailings.

[0030] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A magnetic separation method for increasing iron content and reducing silicon content in mixed iron ore and iron concentrate, characterized in that: The method comprises the following steps: Step 1, optimizing the weak magnetic separation concentration; Step 2, weak magnetic separation step scanning; Step 3, weak magnetic sweeping and separation of tailings; Step 4: One rough and one sweep strong magnetic separation; Step 5, weak magnetic sweeping concentrate, strong magnetic sweeping concentrate and re-grinding; Step 6: Reselect the cyclone overflow.

2. The method for magnetic separation of mixed iron ore and iron concentrate for increasing iron content and reducing silicon content according to claim 1, characterized in that: Step 1, optimize the weak magnetic separation concentration, as follows: Under the condition that the weak magnetic separation magnetic field strength is 2000Oe, adjust the weak magnetic separation concentration, perform weak magnetic separation on the mixed iron ore rough iron concentrate slurry, and determine the optimal weak magnetic separation concentration to be 14.3%, the weak magnetic concentrate w(TFe) 64.91%, and w(SiO2) 3.02%.

3. The magnetic separation method for increasing iron content and reducing silicon content in mixed iron ore and iron coarse concentrate according to claim 2, characterized in that: Step 2, weak magnetic separation cascade sweeping, specifically as follows: weak magnetic roughing separation is performed on the mixed iron ore and iron coarse concentrate slurry to obtain concentrate 1 and tailings 1, and tailings 1 is subjected to weak magnetic sweeping separation to obtain concentrate 2 and tailings 2, the weak magnetic roughing separation magnetic field strength is 450Oe, and the weak magnetic sweeping separation magnetic field strength is 2000Oe.

4. The method for magnetic separation of mixed iron ore and iron coarse concentrate for increasing iron and reducing silicon according to claim 3, characterized in that: Step 3, weak magnetic sweeping tailings separation, specifically as follows: weak magnetic sweeping tailings 2 are separated (0.25mm), and gangue minerals dissociated from iron minerals are discarded in advance. The material on the screen is material 1, which can be used as building sand and gravel, and the material under the screen is material 2, which is subjected to strong magnetic separation.

5. The magnetic separation method for increasing iron and reducing silicon in mixed iron ore and iron coarse concentrate according to claim 4, characterized in that: Step 4, one roughing and one sweeping strong magnetic separation, specifically as follows: subject undersize material 2 to strong magnetic roughing separation to obtain concentrate 3 and tailings 3, and subject tailings 3 to strong magnetic sweeping separation to obtain concentrate 4 and tailings 4, the magnetic field strength of weak magnetic roughing separation is 4500Oe, and the magnetic field strength of strong magnetic sweeping separation is 10000Oe.

6. The method for magnetic separation of mixed iron ore and iron coarse concentrate for increasing iron and reducing silicon according to claim 5, characterized in that: Step 5, re-grinding the weak magnetic scavenging concentrate and the strong magnetic scavenging concentrate, specifically as follows: combine the weak magnetic scavenging concentrate 2 and the strong magnetic scavenging concentrate 4 into the cyclone for classification, the overflow is material 3, which enters the weak magnetic re-selection, the bottom flow is material 4, which is re-grinded in the tower mill, and returns to the cyclone in a closed circuit to meet -0.074mm60%.

7. A magnetic separation method for increasing iron and reducing silicon in mixed iron ore and iron coarse concentrate according to claim 6, characterized in that: Step 6, cyclone overflow reselection, specifically as follows: cyclone overflow material 3 is subjected to weak magnetic reselection to obtain concentrate 5 and tailings 5, tailings 5 ​​are subjected to strong magnetic reselection to obtain concentrate 6 and tailings 6, the magnetic field strength of weak magnetic reselection is 2000Oe, and the magnetic field strength of strong magnetic reselection is 10000Oe, concentrate 1 from weak magnetic roughing, concentrate 3 from strong magnetic roughing, concentrate 5 from weak magnetic reselection and concentrate 6 from strong magnetic reselection are combined as the final concentrate, and tailings 4 from strong magnetic sweeping selection and tailings 6 from strong magnetic reselection are combined as the total tailings.

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