A combined grinding and separation process of maghemitic mixed ore - gravity and magnetic separation

Abstract

The present invention relates to a combined grinding and selection-gravity magnetic process for mixed magma ores, characterized in that the raw ore is divided into a normal ore with a grade of 25%-30% and an extremely lean ore with a grade of 20%-25%, and then the two ores are fed into the process of the present invention for treatment, including the following processes: 1) grinding: the normal ore is fed into the main process for primary grinding and classification, weak magnetic and strong magnetic tailings discarding and secondary grinding and classification; the extremely lean ore is fed into closed-circuit semi-autogenous grinding, coarse-grained weak magnetic and strong magnetic tailings discarding and two-stage continuous grinding and classification; 2) selection: the grinding products are combined and fed into the two-stage weak magnetic and strong magnetic tailings discarding, continuous weak magnetic process and centrifuge process to obtain a final concentrate grade of more than 67%. The advantages of the present invention are: 1) it can adapt to the changes in the properties of the raw ore, realize the coordinated ore matching in the ore dressing plant, and is conducive to stable production; 2) the spiral chute operation is cancelled and the centrifuge operation is used instead of the flotation operation, simplifying the process and achieving the effect of reducing costs and stabilizing production.

Description

Technical Field

[0001] The invention belongs to the technical field of iron ore dressing technology, and in particular relates to a separation and grinding and separation-gravity and magnetic combined process of maghemitic mixed ore. Background Art

[0002] At present, the main separation process for Anshan-type hematite ore adopts stage grinding, coarse and fine separation, gravity separation-strong magnetic-anion reverse flotation process. The raw ore is crushed to a particle size of 12-0mm by coarse crushing, medium crushing and fine crushing screening systems, and is fed into a closed-circuit grinding system composed of an overflow ball mill and a cyclone group. The primary overflow is fed into an involute cyclone group to be graded into coarse and fine materials. The coarse and fine classification cyclone sedimentation is fed into a three-stage spiral chute for roughing, fine selection and scavenging to obtain gravity separation concentrate. The scavenging snail tailings are fed into permanent magnets and scavenging medium magnets to obtain gravity separation tailings. The refined snail tailings, scavenging snail concentrate, permanent magnet concentrate and scavenging medium magnetic concentrate are fed into a secondary grinding-classification system together, and the overflow returns to the coarse and fine classification operation. The overflow of the coarse and fine cyclone is fed to the permanent magnet operation, and the permanent magnet tailings are fed to the thickener for concentration. The bottom flow is fed to the strong magnetic machine through a slag removal screen, and the strong magnetic tailings are discarded; the permanent magnetic concentrate and the strong magnetic concentrate are combined and fed to the thickener for concentration, and the bottom flow of the thickener is fed to the flotation operation compressor, and the bottom flow is fed to the flotation operation. After a roughing operation, a concentrating operation, and three scavenging operations, the flotation concentrate is obtained, and the flotation tailings are discarded. The first scavenging concentrate and the concentrating tailings are returned to the roughing operation, and the gravity concentrate and the flotation concentrate are combined to become the final concentrate, with a grade of more than 67%. The traditional hematite beneficiation process is shown in Figure 1 .

[0003] Production practice shows that the traditional process of "stage grinding, coarse and fine separation, gravity separation-strong magnetic separation-anion reverse flotation" for hematite has the following problems: First, the properties of the ore coming from the mine have changed greatly in recent years, and the mine cannot strictly implement the ore matching system. The grade of the raw ore fluctuates greatly, and the production of the ore dressing plant is very passive. In order to cope with this change, the raw ore with a grade of 25%-30% is called normal ore, and the raw ore with a grade of 20%-25% is called extremely lean ore. By changing the ore dressing process parameters, we try our best to keep the production normal. However, the traditional process flow fluctuates greatly when processing these two types of raw ores and concentrates, and the production is often unstable. In addition, in addition to the raw ore In addition to the frequent phenomenon of ore grade depletion, the magnetic ore content of the original ore has increased significantly. The ferrous iron content of the original ore has increased from 1-3.35% in the early stage of production to 6.5-7.54%. In some periods, the magnetic ore content even reached 80%. Therefore, the process of using weak magnetic separation to extract the concentrate is more suitable for the needs of future changes in ore properties; second, the traditional separation process includes three main processes: gravity, magnetic, and flotation. The process is long and complicated, difficult to control, and also causes unstable production technical indicators; third, the practice of using spiral chute as gravity separation equipment shows that the yield of gravity separation concentrate is low (between 8% and 9%), and its grade is also low (between 66% and 66.5%), and the large circulation of intermediate ore causes the various operations to affect each other.

[0004] In order to solve a series of problems such as large changes in ore properties, frequent depletion of original ore grade, unsatisfactory ore blending effect in the mine, large fluctuations in production indicators of the beneficiation plant, and long and complicated beneficiation process, mineral processing researchers have done a lot of exploration on the separation, grinding and combined selection of red magnetic mixed ore - gravity and magnetic combined process technology, and have made a series of technological advances in separation technology and research and development of new beneficiation equipment. High-efficiency and energy-saving grinding and selection equipment such as vertical stirred mill and high-efficiency magnetic separator have been successively applied to major mines, and great progress has been made.

[0005] The two invention patents with patent numbers CN201510320314.4 and CN201510320813.3 introduce the coarse-grained preselection, magnetic-gravity separation process and the coarse-grained preselection, magnetic-flotation separation process to separate fine-grained mixed ore. They are characterized by using the "semi-autogenous grinding, wet preselection, continuous grinding, weak magnetic-strong magnetic, fine screen re-grinding, strong magnetic fine gravity separation" operating system and the "semi-autogenous grinding, wet preselection, continuous grinding, weak magnetic-strong magnetic, fine screen re-grinding, strong magnetic fine reverse flotation" operating system to separate fine-grained mixed ore. Both invention patents use two-stage grinding-fine screen re-grinding operations. The outstanding problem in production is that the screen surface is easily blocked and worn, resulting in low screening efficiency, large circulating load, and serious over-grinding, which affects both the mill processing capacity and the separation index. The invention patent with the patent number CN201810729014.5 introduces a magnetite high-pressure roller mill-wet pre-selection-stage grinding-tower mill magnetic separation process, which is characterized by feeding the high-pressure roller mill-screening operation product into the pre-magnetic operation, a closed-circuit grinding operation, a two-stage closed-circuit grinding operation consisting of a secondary cyclone classification and a two-stage tower mill, and a continuous three-stage magnetic separation operation to obtain a final concentrate with a grade of more than 67.5% and a comprehensive tailings with a grade of 8.5%-9.5%. This process belongs to the full magnetic process and is suitable for selecting high-grade magnetite, but when the mine is low-grade magnetic hematite, since this invention patent can only select magnetic ore, it will cause a large amount of hematite loss, which is not conducive to the recycling of lean iron ore resources. Summary of the invention

[0006] In view of the problem that the existing technology is difficult to adapt to the coordinated processing of normal ore and extremely lean ore, and there are problems such as long ore dressing process flow, complexity and difficulty in control, the purpose of the present invention is to provide a separation and grinding of magnetic red mixed ore - gravity and magnetic combined process,

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The invention discloses a separation and grinding and separation-gravity and magnetic combined process for mixed magma ore, characterized in that the mixed magma ore is divided into normal ore and extremely lean ore according to the grade of the raw ore from the mine, wherein the grade of the normal ore is 25%-30% and the particle size is 12-0 mm, and the grade of the extremely lean ore is 20%-25% and the particle size is 250-0 mm, and then the two ores are fed into the separation and grinding-gravity and magnetic combined process for subsequent grinding and separation, which specifically comprises the following steps:

[0009] Step 1: feed the normal ore into a closed-circuit grinding and classification operation to obtain a first-classification overflow product, feed the first-classification overflow product into a weak magnetic and a strong magnetic operation, discard the strong magnetic tailings, combine the weak magnetic concentrate and the strong magnetic concentrate, and feed them into a secondary closed-circuit grinding and classification operation to obtain a secondary classification overflow product;

[0010] Step 2: Feed the extremely lean ore into a closed-circuit semi-autogenous grinding operation to obtain a linear screen undersize product, feed the undersize product into a coarse-grained weak magnetic and coarse-grained strong magnetic operation, discard the coarse-grained strong magnetic tailings, combine the coarse-grained weak magnetic concentrate and the coarse-grained strong magnetic concentrate, and feed them into a two-stage continuous grinding and classification operation to obtain a two-stage classification overflow product;

[0011] Step 3, combining the secondary classification overflow product and the second stage classification overflow product obtained in step 1 and step 2 into a combined feed;

[0012] Step 4: feed the combined feed into the second-stage weak magnetic operation for separation to obtain the second-stage weak magnetic concentrate and the second-stage weak magnetic tailings; feed the second-stage weak magnetic tailings into the second-stage strong magnetic operation for separation to obtain the second-stage strong magnetic concentrate and the second-stage strong magnetic tailings; the second-stage strong magnetic tailings are discarded; the second-stage weak magnetic concentrate is fed into two consecutive three-stage weak magnetic operations and four-stage weak magnetic operations for separation to obtain the four-stage weak magnetic concentrate, the three-stage weak magnetic tailings and the four-stage weak magnetic tailings; the two-stage strong magnetic concentrate, the three-stage weak magnetic operation, the four-stage weak magnetic tailings, and the four-stage weak magnetic tailings. The magnetic tailings and four-stage weak magnetic tailings are combined and fed into a coarse, a fine and a sweeping centrifuge for separation to obtain centrifuge concentrate and centrifuge tailings. The centrifuge tailings are discarded, and the centrifuge concentrate and the four-stage weak magnetic concentrate are combined into the final concentrate. The final concentrate grade reaches more than 67%. The final tailings are composed of the first-stage strong magnetic tailings, coarse-grained strong magnetic tailings, the second-stage strong magnetic tailings and the centrifuge tailings. The final tailings grade is below 9.5%.

[0013] The closed-circuit semi-autogenous grinding operation is composed of a semi-autogenous grinding machine and a linear screen.

[0014] The grinding equipment used in the secondary closed-circuit grinding and classification operation is a tower mill.

[0015] The magnetic separator used in the three-stage weak magnetic operation is an elutriator.

[0016] The magnetic separator used in the four-stage weak magnetic operation is a magnetic vibration machine.

[0017] The centrifuge is a SLon-800 centrifugal ore dressing machine.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] 1) The present invention can adapt to the change of the properties of the raw ore, realize the coordinated ore matching of normal ore (grade of 25%-30%) and extremely lean ore (grade of 20%-25%) in the ore dressing plant, and ensure the normal and stable production of the ore dressing process; the main process can process 8 million tons of normal ore per year, and the added "semi-autogenous grinding-coarse particle pre-selection" process system can process extremely lean ore per year up to 4.5 million tons per year, meeting the ore dressing plant's 12.5 million tons per year ore processing capacity, and it is expected to increase the iron concentrate with a grade of more than 67% by more than 1 million tons, thereby improving the resource utilization rate of iron ore;

[0020] 2) The present invention eliminates the spiral chute operation, uses a centrifuge to replace the flotation process, adopts a tower mill and a high-efficiency magnetic separator, simplifies and optimizes the process flow, and achieves the effects of fine grinding and selection, cost reduction and stable production;

[0021] 3) The present invention is characterized in that the main process ball mill system and the semi-autogenous grinding-pre-selection supplementary system are relatively independent, which is convenient for production organization and operation management. When it comes to separation operation, the two ores are combined to achieve the effect of "separate grinding and combined separation", realizing the separation of normal ore and extremely lean ore of maghemitic mixed ore, and opening up a new way for the efficient separation of maghemitic mixed ore. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the flow chart of the traditional hematite beneficiation process.

[0023] Figure 2 It is a flow chart of the mineral processing process of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Example

[0025] The normal ore in the embodiment of the present invention was taken from the crushing workshop of a mineral processing plant in Anshan. The phase analysis results and chemical multi-element analysis results of the normal ore are shown in Tables 1 and 2; the extremely lean ore was taken from the semi-autogenous grinding pre-selection workshop, and the phase analysis results and chemical multi-element analysis results of the extremely lean ore are shown in Tables 3 and 4.

[0026] Table 1 Normal mineral phase analysis results

[0027] Iron phase TFe <![CDATA[FeCO 3 ]]> <![CDATA[FeSiO 3 ]]> <![CDATA[Fe 3 THE 4 ]]> Red, brown content(%) 27.33 1.03 1.40 20.40 4.50 Distribution rate (%) 100.00 3.77 5.12 74.64 16.47

[0028] Table 2 Results of multi-element analysis of normal ore chemistry

[0029] name FeO <![CDATA[SiO 2 ]]> CaO MgO <![CDATA[Al 2 THE 3 ]]> MnO S P Ig <![CDATA[TiO 2 ]]> content(%) 9.80 48.34 4.03 3.61 0.03 0.121 0.022 0.024 1.72 0.006

[0030] Table 3 Analysis results of extremely poor mineral phases

[0031] Iron phase TFe <![CDATA[FeCO 3 ]]> <![CDATA[FeSiO 3 ]]> <![CDATA[Fe 3 THE 4 ]]> Red, brown content(%) 22.85 0.50 1.85 4.20 16.30 Distribution rate (%) 100.00 2.19 8.10 18.38 71.33

[0032] Table 4 Chemical multi-element analysis results of extremely lean ores

[0033] name FeO <![CDATA[SiO 2 ]]> CaO MgO <![CDATA[Al 2 THE 3 ]]> MnO S P Ig <![CDATA[TiO 2 ]]> content(%) 1.90 62.64 0.18 0.33 0.59 0.032 0.008 0.011 0.55 0.016

[0034] like Figure 2As shown, a combined grinding and separation-magnetic gravity process of a mixed maghemitic ore of the present invention is characterized in that the mixed maghemitic ore is divided into normal ore and extremely lean ore according to the grade of the original ore from the mine, the grade of the normal ore is 27.33%, the particle size is 12-0mm, the grade of the extremely lean ore is 22.85%, and the particle size is 250-0mm, and then the two ores are fed into the combined grinding and separation-magnetic gravity process of the present invention for subsequent grinding and separation processing, which specifically includes the following steps:

[0035] Step 1, feed the normal ore with a grade of 27.33% and a particle size of 12-0mm after crushing into a closed-circuit grinding and classification operation to obtain a first-classification overflow product, the particle size of the first-classification overflow product reaches -200 mesh, accounting for 60%, and the first-classification overflow product is fed into a weak magnetic and a strong magnetic operation, and a strong magnetic tailing is discarded, and a strong magnetic tailing with a yield of 21.34% and a grade of 5.93% is discarded. A weak magnetic concentrate and a strong magnetic concentrate are combined into a mixed magnetic concentrate, and the grade of the mixed magnetic concentrate is 38.03%, and the yield is 42.66%. Then the mixed magnetic concentrate is fed into a secondary closed-circuit grinding and classification operation, and the mill adopts a tower mill to obtain a secondary classification overflow product; the particle size of the secondary classification overflow product reaches -325 mesh, accounting for 93%.

[0036] Step 2, the extremely lean ore with a grade of 22.85% and a particle size of 250-0mm is fed into a closed-circuit semi-autogenous grinding operation. The closed-circuit semi-autogenous grinding operation adopts a combination of a semi-autogenous grinder and a linear screen to obtain a linear screen underscreen product, and the underscreen product is fed into a coarse-grained weak magnetic and coarse-grained strong magnetic operation. The coarse-grained strong magnetic tailings are discarded, and the coarse-grained tailings with a grade of 8.64% and a yield of 14.28% are discarded. The coarse-grained weak magnetic concentrate and the coarse-grained strong magnetic concentrate are combined into a coarse-grained mixed magnetic concentrate. The coarse-grained mixed magnetic concentrate has a grade of 32.19% and a yield of 21.72%. Then the coarse-grained mixed magnetic concentrate is fed into a two-stage continuous grinding and classification operation to obtain a second-stage classification overflow product. The particle size of the second-stage classification overflow product reaches -325 mesh 95%.

[0037] Step 3: Combine the secondary classification overflow product and the second stage classification overflow product obtained in step 1 and step 2 into a combined feed.

[0038] Step 4: Feed the combined feed into the second-stage weak magnetic operation for separation to obtain the second-stage weak magnetic concentrate and the second-stage weak magnetic tailings. The second-stage weak magnetic concentrate has a grade of 64.33% and a yield of 20.18%, and the second-stage weak magnetic tailings has a grade of 23.15% and a yield of 44.20%. Feed the second-stage weak magnetic tailings into the second-stage strong magnetic operation for separation to obtain the second-stage strong magnetic concentrate and the second-stage strong magnetic tailings, and discard the second-stage strong magnetic tailings with a grade of 9.43% and a yield of 25.54%. Feed the second-stage weak magnetic concentrate into two consecutive three-stage weak magnetic operations and four-stage weak magnetic operations for selection to obtain the four-stage weak magnetic concentrate, the three-stage weak magnetic tailings and the four-stage weak magnetic tailings. The grade of the four-stage weak magnetic concentrate is 68.08% and the yield is 1 8.33%; the second-stage strong magnetic concentrate, the third-stage weak magnetic tailings and the fourth-stage weak magnetic tailings are combined and fed into a coarse, a fine and a sweeping centrifuge for separation to obtain centrifuge concentrate and centrifuge tailings. The centrifuge tailings with a grade of 17.54% and a yield of 10.67% are discarded. The centrifuge concentrate has a grade of 65.56% and a yield of 9.84%; the centrifuge concentrate and the fourth-stage weak magnetic concentrate are combined into the final concentrate. The final concentrate grade is 67.20% and the yield is 28.17%. The final tailings are composed of the first-stage strong magnetic tailings, coarse-grained strong magnetic tailings, the second-stage strong magnetic tailings and the centrifuge tailings. The final tailings grade is 9.44% and the yield is 71.83%.

[0039] The present invention processes extremely lean ores by adding a semi-autogenous grinding-coarse particle pre-selection process, thereby realizing "separate grinding" of normal ores and extremely lean ores, and simultaneously coordinates or smoothly converts the processing of normal ores and extremely lean ores, thereby realizing ore blending in a beneficiation plant; in addition, the spiral chute operation is cancelled, and the flotation operation is replaced by the centrifuge operation, and a tower mill and a high-efficiency magnetic separator are adopted to simplify the separation process, thereby realizing "combined selection" of normal ores and extremely lean ores, which is beneficial to reducing production costs and improving separation efficiency.

Claims

1. A combined process of separation, grinding and separation of maghemitic mixed ore and gravity and magnetic separation, characterized in that: The mixed magma ore is divided into normal ore and extremely lean ore according to the grade of the raw ore from the mine. The grade of normal ore is 25%-30% and the particle size is 12-0mm. The grade of extremely lean ore is 20%-25% and the particle size is 250-0mm. Then the two kinds of ores are fed into the separation and grinding-gravity-magnetic combined process for subsequent grinding and separation treatment, which specifically includes the following steps: Step 1: feed the normal ore into a closed-circuit grinding and classification operation to obtain a first-classification overflow product, feed the first-classification overflow product into a weak magnetic and a strong magnetic operation, discard the strong magnetic tailings, combine the weak magnetic concentrate and the strong magnetic concentrate, and feed them into a secondary closed-circuit grinding and classification operation to obtain a secondary classification overflow product; Step 2: Feed the extremely lean ore into a closed-circuit semi-autogenous grinding operation to obtain a linear screen undersize product, feed the undersize product into a coarse-grained weak magnetic and coarse-grained strong magnetic operation, discard the coarse-grained strong magnetic tailings, combine the coarse-grained weak magnetic concentrate and the coarse-grained strong magnetic concentrate, and feed them into a two-stage continuous grinding and classification operation to obtain a two-stage classification overflow product; Step 3, combining the secondary classification overflow product and the second stage classification overflow product obtained in step 1 and step 2 into a combined feed; Step 4: Feed the combined feed into the second-stage weak magnetic operation for separation to obtain the second-stage weak magnetic concentrate and the second-stage weak magnetic tailings; feed the second-stage weak magnetic tailings into the second-stage strong magnetic operation for separation to obtain the second-stage strong magnetic concentrate and the second-stage strong magnetic tailings; discard the second-stage strong magnetic tailings; feed the second-stage weak magnetic concentrate into two consecutive three-stage weak magnetic operations and four-stage weak magnetic operations for separation to obtain the four-stage weak magnetic concentrate, the three-stage weak magnetic tailings and the four-stage weak magnetic tailings; the two-stage strong magnetic concentrate, the three-stage weak magnetic The tailings and four-stage weak magnetic tailings are combined and fed into a coarse, a fine and a sweeping centrifuge for selection to obtain centrifuge concentrate and centrifuge tailings. The centrifuge tailings are discarded, and the centrifuge concentrate and the four-stage weak magnetic concentrate are combined into the final concentrate. The final concentrate grade reaches more than 67%. The final tailings are composed of the first-stage strong magnetic tailings, coarse-grained strong magnetic tailings, the second-stage strong magnetic tailings and the centrifuge tailings. The final tailings grade is below 9.5%.

2. The grinding and separation-gravity-magnetic combined process of a maghemitic mixed ore according to claim 1 is characterized in that: The closed-circuit semi-autogenous grinding operation is composed of a semi-autogenous grinding machine and a linear screen.

3. The grinding and separation-gravity-magnetic combined process of a maghemitic mixed ore according to claim 1 is characterized in that: The grinding equipment used in the secondary closed-circuit grinding and classification operation is a tower mill.

4. The grinding and separation-gravity-magnetic combined process of a maghemitic mixed ore according to claim 1, characterized in that: The magnetic separator used in the three-stage weak magnetic operation is an elutriator.

5. The separation and separation-gravity-magnetic combined process of maghemitic mixed ore according to claim 1 is characterized in that: The magnetic separator used in the four-stage weak magnetic operation is a magnetic vibration machine.

6. The grinding and separation-gravity-magnetic combined process of maghemitic mixed ore according to claim 1, characterized in that: The centrifuge is a SLon-800 centrifugal ore concentrator.

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