Dry separation process for fine particles of magnetite

Abstract

The invention discloses a fine particle dry separation process for magnetite, and belongs to the technical field of mineral processing. The process comprises the following steps: firstly, crushing and screening raw magnetite, and classifying undersize products into two particle fractions; wherein magnetite is recovered from one fraction through magnetic pulley roughing and scavenging, and dry concentrate is obtained from the other fraction through separation of a dry separator; after magnetic pulley roughing and scavenging concentrate are combined, the concentrate is crushed through a fine particle crusher and then screened through a micro-powder sieve, secondary dry separation and waste throwing are conducted, finally dry separation concentrate enters a fine ore bin, and dry separation tailings serve as sand materials to be utilized; according to the process, gangue minerals can be effectively removed through grading separation and multi-section purification, the loss of micro-fine particle magnetite is reduced, the grade of wet separation raw ore is remarkably improved, meanwhile, the treatment capacity and cost of follow-up grinding separation operation are reduced, the operation process is simple, the large-scale magnetite separation production requirement is met, and good economic benefits and practicability are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of mineral processing, in particular to a fine-grained dry separation process of magnetite. Background Art

[0002] With the continuous development of magnetite beneficiation technology, "more crushing, less grinding, and early tailings disposal" has become a core measure for magnetite beneficiation plants to improve economic efficiency. Relying on the continuous advancement of fine-grain crushing technology, this has laid the foundation for the production of small-scale dry-discarding of magnetite and the early disposal of tailings of fine-grained magnetite.

[0003] At present, magnetic pulleys are mostly used for large-scale dry throwing operations, but they have obvious limitations. Some magnetite inclusions and conjoined bodies are easily thrown out and lost in the tailings. In addition, the grade improvement of magnetite wet ore is limited, causing a large amount of gangue to enter subsequent operations, increasing grinding and selection costs.

[0004] In response to the above problems, there is an urgent need for a fine particle dry separation process that can adapt to different particle sizes and improve separation efficiency and grade. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a fine-grained dry separation process for magnetite, which can effectively separate magnetite and gangue minerals, improve the grade of wet-separated ore, and effectively reduce the grinding cost and process operation difficulty.

[0006] To achieve the above object, the present invention provides the following technical solution: a fine particle dry separation process of magnetite, comprising the following steps: Step 1: The magnetite ore is crushed and then screened. The oversize product is returned to the crushing system, and the undersize product enters the classification process; Step 2: The undersize product of step 1 is classified into two particle sizes, and the two particle sizes are respectively sent to the magnetic pulley for dry separation and the dry separator for dry separation; Step 3: Use a magnetic pulley to dry-select and discard the products of one of the particle sizes to obtain a magnetic pulley roughing concentrate and a magnetic pulley roughing tailings; Step 4: Use a magnetic pulley to scavenge the magnetic pulley roughing tailings in step 3 to obtain magnetic pulley scavenging concentrate and magnetic pulley dry-throwing tailings; Step 5: Use a dry separator to separate the product of another particle size in step 2 to obtain dry concentrate and dry tailings; Step 6: Combine the roughing concentrate from the magnetic pulley in step 3 and the scavenging concentrate from the magnetic pulley in step 4 and send them to a fine crusher for crushing; Step 7: The fine crushed product from step 6 and the dry-selected concentrate from step 5 are sent to the micro-powder screen for screening. The product on the screen is returned to the fine crusher for further crushing, and the qualified product under the screen enters the next step; Step 8: Use a dry separator to dry-select the qualified products under the screen in step 7. The dry-selected concentrate enters the fine ore bin, and the dry-selected tailings are used as sand.

[0007] Preferably, in step 2, after classification of the undersize product, two particle size products of 15-30 mm and -15 mm are obtained, wherein the 15-30 mm particle size enters the magnetic pulley for dry separation, and the -15 mm particle size enters the dry separation machine for dry separation.

[0008] Preferably, in step 1, the particle size of the product under the screen after the raw ore is crushed and screened is ≤30 mm.

[0009] Preferably, in step 3, the magnetic pulley used is a CTDG magnetic pulley, and the magnetic field strength is 0.35T.

[0010] Preferably, in step 4, the magnetic pulley used is a CTDG magnetic pulley, and the magnetic field strength is 0.40T.

[0011] Preferably, in step 5, the dry separator used is a powder ore dry separator, and the magnetic field strength is 0.40T.

[0012] Preferably, in step 7, the particle size of the qualified product screened by the micro powder sieve is ≤3 mm.

[0013] Preferably, in step 8, the dry separator used is a powder ore dry separator, and the magnetic field strength is 0.60T.

[0014] Compared with the prior art, the present invention provides a fine-grained dry separation process for magnetite, which has the following beneficial effects: 1. The magnetic pulley is used to perform "roughing + sweeping" on small pieces of magnetite with a particle size of 15-30mm, which can preliminarily remove some gangue minerals, reduce the processing volume of fine crushing operations, and reduce equipment energy consumption and operating costs; 2. Dry separation schemes are designed for 15-30mm and -15mm particle sizes, especially for the special treatment of -15mm fine particle size, which can increase the recovery rate of fine magnetite to more than 90%, avoiding the problem of "fine particles running away" in traditional processes; 3. Through the secondary dry separation of products with a particle size of ≤3mm using a powder ore dry separator, the total iron grade of the wet-selected ore can be increased to more than 35%, and the magnetic iron recovery rate is around 90%. This significantly reduces the fineness of subsequent wet-selected grinding while lowering the beneficiation ratio and increasing the output of iron ore concentrate.

[0015] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the description, the following preferred embodiments of the present invention are described in detail with reference to the accompanying drawings. The specific implementation methods of the present invention are given in detail by the following embodiments and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0017] The present invention targets the magnetite ore from the Dongwufenzi Ore Dressing Plant of Inner Mongolia Dazhong Mining Co., Ltd. Testing shows that the total iron (TFe) grade of the ore is 24.12%, the magnetic iron (mFe) grade is 19.28%, and the gangue components are mainly quartz and feldspar. This process is required to remove gangue and improve the grade of the ore, providing qualified raw materials for subsequent wet separation operations.

[0018] Step 1: Crushing and screening of raw ore; The HP500 cone crusher is used to crush the magnetite ore. After crushing, the material is sent to a high-frequency vibrating screen for screening. The particle size of the undersize product after screening is strictly controlled to ≤30mm. This particle size range can meet the basic particle size requirements of subsequent grading. The oversize product (particle size >30mm) is returned to the HP500 cone crusher for re-crushing, forming a circular crushing process to ensure that all materials entering subsequent processes meet the particle size standards.

[0019] Step 2: Grading of undersize products; The ≤30mm undersize product obtained in step 1 is sent to a high-frequency vibrating screen for secondary classification. By adjusting the screen parameters, two products of 15-30mm particle size and -15mm particle size are accurately separated. Among them, the 15-30mm particle size product is sent to the magnetic pulley for dry sorting due to its larger particle size, and the -15mm particle size product is a fine-grained material and is sent to the dry separator for targeted sorting, thereby realizing the classified processing of materials of different particle sizes and laying the foundation for subsequent efficient sorting.

[0020] Step 3: Magnetic pulley roughing; A CTDG magnetic pulley was used to rough the 15-30mm particle size product from step 2, with a magnetic field strength of 0.35T. At this magnetic field strength, the pulley effectively attracted magnetite within the particle size range, separating the rougher concentrate from the tailings. Testing showed that after this roughing operation, the rougher concentrate yield was 69.51%, the total iron grade increased to 36.70%, the recovery rate reached 89.04%, the magnetic iron grade was 33.90%, and the magnetic iron recovery rate was 93.13%, achieving initial gangue removal and concentrate enrichment.

[0021] Step 4: Magnetic pulley sweeping; Using the same type of magnetic pulley (CTDG) as in step 3, the magnetic field strength was increased to 0.40 T for scavenging of the rougher tailings produced in step 3. The higher magnetic field strength recovered residual magnetite from the rougher tailings, reducing magnetite loss. This scavenging process yielded a 17.63% scavenger concentrate and dry-throw tailings. The scavenger concentrate yield was 17.63%, the total iron grade was 27.40%, the recovery rate was 46.68%, the magnetic iron grade was 21.50%, and the magnetic iron recovery rate reached 90.26%, further improving magnetite resource utilization. The dry-throw tailings (total iron grade of 6.70%, magnetic iron grade of 0.50%) were used as sand and gravel aggregate.

[0022] Step 5: Dry separator sorting (-15mm particle size); A fine ore dry sorter was used to finely separate the -15mm fine product from step 2. The magnetic field strength of the dry sorter was set to 0.40T. This effectively separated the magnetite from the gangue, producing a dry-sort concentrate and tailings. Testing showed a dry-sort concentrate yield of 37.03%, a total iron grade of 25.80%, an operating recovery of 60.86%, a magnetic iron grade of 20.70%, and a magnetic iron operating recovery of 94.64%. The dry-sort tailings (total iron grade of 9.76%, magnetic iron grade of 0.69%) were discarded as fine gangue.

[0023] Step 6: fine particle crushing; The magnetic pulley roughing concentrate obtained in step 3 and the magnetic pulley scavenging concentrate obtained in step 4 are combined and sent to the fine-grained crusher for crushing. The fine-grained crusher crushes the combined rough concentrate to a finer particle size through the lamination crushing principle, creating conditions for subsequent secondary screening and dry separation to improve quality. At the same time, it complies with the mineral processing concept of "more crushing and less grinding" and reduces the load of subsequent grinding operations.

[0024] Step 7: Screening and grading of fine crushed products; The product crushed by the fine-grained crusher in step 6 and the dry-selected concentrate in step 5 are sent to the micro-powder screen for screening. The particle size of the qualified product under the screen is strictly controlled to be ≤3mm, which can meet the material fineness requirements of the subsequent secondary dry selection; the product on the screen (particle size >3mm) is returned to the fine-grained crusher for re-crushing, forming a circular screening and crushing process to ensure that the materials entering the secondary dry selection are all qualified fine-grained products.

[0025] Step 8: Secondary dry selection and discarding; A fine ore dry sorter was used to perform a secondary dry sorting on the qualified undersize product (≤3mm) from step 7. The magnetic field strength of the dry sorter was set to 0.60T. The fine ore dry sorter has efficient fine-grain separation capabilities, further removing residual fine gangue from the material. The resulting dry-sort concentrate was stored in a fine ore bin and used as feedstock for subsequent wet sorting operations. The dry-sort tailings were recycled as sand. The resulting concentrate yield was 81.49%, with a total iron grade of 36.41%. The recovery rate was 94.52%, the magnetic iron grade was 31.71%, and the magnetic iron recovery rate reached 99.31%. The dry-sort tailings (with a total iron grade of 9.29% and a magnetic iron grade of 0.97%) achieved efficient enrichment and purification of magnetite.

[0026] Through the process operation of this embodiment, the magnetite ore (24.12% total iron, 19.28% magnetic iron) is finally converted into a dry-selected concentrate with a total iron grade of 36.41% and a magnetic iron grade of 31.71%. More than 95% of the magnetic iron can be recovered, which significantly improves the grade of the wet-selected ore. At the same time, by discarding the tailings in advance, the processing volume of subsequent grinding operations is reduced, thereby reducing the grinding cost and energy consumption.

[0027] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A fine particle dry separation process of magnetite, characterized in that: The following steps are involved: Step 1: The magnetite ore is crushed and then screened. The oversize product is returned to the crushing system, and the undersize product enters the classification process; Step 2: The undersize product of step 1 is classified into two particle sizes, and the two particle sizes are respectively sent to the magnetic pulley for dry separation and the dry separator for dry separation; Step 3: Use a magnetic pulley to dry-select and discard the products of one of the particle sizes to obtain a magnetic pulley roughing concentrate and a magnetic pulley roughing tailings; Step 4: Use a magnetic pulley to scavenge the magnetic pulley roughing tailings in step 3 to obtain magnetic pulley scavenging concentrate and magnetic pulley dry-throwing tailings; Step 5: Use a dry separator to separate the product of another particle size in step 2 to obtain dry concentrate and dry tailings; Step 6: Combine the roughing concentrate from the magnetic pulley in step 3 and the scavenging concentrate from the magnetic pulley in step 4 and send them to a fine crusher for crushing; Step 7: The fine crushed product from step 6 and the dry-selected concentrate from step 5 are sent to the micro-powder screen for screening. The product on the screen is returned to the fine crusher for further crushing, and the qualified product under the screen enters the next step; Step 8: Use a dry separator to dry-select the qualified products under the screen in step 7. The dry-selected concentrate enters the fine ore bin, and the dry-selected tailings are used as sand.

2. The fine particle dry separation process of magnetite according to claim 1, characterized in that: In the step 2, after the sieve product is classified, two particle size products of 15-30mm and -15mm are obtained, wherein the 15-30mm particle size enters the magnetic pulley for dry separation, and the -15mm particle size enters the dry separation machine for dry separation.

3. The fine particle dry separation process of magnetite according to claim 1, characterized in that: In the step 1, the particle size of the product under the screen after the raw ore is crushed and screened is ≤30 mm.

4. The fine particle dry separation process of magnetite according to claim 1, characterized in that: In step 3, the magnetic pulley used is a CTDG magnetic pulley, and the magnetic field strength is 0.35T.

5. The fine particle dry separation process of magnetite according to claim 1, characterized in that: In step 4, the magnetic pulley used is a CTDG magnetic pulley, and the magnetic field strength is 0.40T.

6. The fine particle dry separation process of magnetite according to claim 1, characterized in that: In step 5, the dry separator used is a powder ore dry separator with a magnetic field strength of 0.40T.

7. The fine particle dry separation process of magnetite according to claim 1, characterized in that: In step 7, the particle size of the qualified product screened by the micro powder sieve is ≤3 mm.

8. The fine particle dry separation process of magnetite according to claim 1, characterized in that: In step 8, the dry separator used is a powder ore dry separator, and the magnetic field strength is 0.60T.

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