A method for improving iron ore separation efficiency from red mud using hydrocyclones

Abstract

This invention belongs to the field of red mud iron ore beneficiation technology, specifically a method for improving the efficiency of red mud iron ore beneficiation using hydrocyclones. The method comprises the following steps: S1. The underflow red mud slurry from the final washing settling tank of an alumina plant is transported to a red mud mixing tank and mixed to form a qualified slurry; S2. The qualified slurry is pumped into a hydrocyclone for particle size classification; S3. The underflow product is directly transported to a magnetic separator for magnetic separation to obtain iron concentrate and magnetic tailings; S4. The overflow product is transported to a tailings thickener for concentration, and the concentrated overflow slurry is transported to a red mud filter press for filtration. The system implementing this method includes a red mud mixing tank, a hydrocyclone assembly, a high-gradient magnetic separator, etc., equipped with a PLC control unit. The hydrocyclone assembly is connected in parallel to adapt to industrial production. This invention effectively improves iron ore beneficiation efficiency and has significant overall benefits.

Description

Technical Field

[0001] This invention relates to the field of red mud iron ore beneficiation technology, specifically a method for improving the efficiency of red mud iron ore beneficiation by using hydrocyclones for classification. Background Technology

[0002] Red mud is a large amount of solid waste generated during alumina production. Its production increases in tandem with alumina output. Large-scale red mud stockpiling not only occupies valuable land resources but also poses environmental risks such as leaching and dust generation, making it a pressing solid waste disposal problem for the alumina industry. Red mud contains a certain amount of iron resources, primarily in the form of minerals such as hematite and goethite. Recovering the iron resources from red mud and achieving its resource utilization can reduce red mud stockpiles, alleviate environmental pressure, and create additional economic benefits, representing an important development direction for the comprehensive utilization of red mud.

[0003] Currently, the main industrial method for extracting iron resources from red mud is direct high-intensity magnetic separation. This process directly separates the red mud slurry using magnetic separation. However, red mud itself has extremely fine particles and a wide particle size distribution. A large number of fine-grained iron-containing minerals easily form magnetic agglomerates during magnetic separation, and non-magnetic entrainment also occurs. These two problems directly lead to low-grade iron concentrate and high iron content in the tailings, resulting in suboptimal overall separation efficiency. Under current processes, the iron concentrate grade can only reach 51%, and the iron recovery rate is only 28.0%. Furthermore, the fine particles in red mud significantly increase the viscosity of the slurry, further interfering with the effective separation of iron minerals and gangue during magnetic separation, exacerbating the poor separation effect.

[0004] Hydrocyclones are commonly used particle size classification and concentration devices in the mining and metallurgical industries. They utilize centrifugal force to achieve rapid separation of materials of different particle sizes, offering advantages such as simple structure, high operating efficiency, and convenient operation. They are widely used in pretreatment operations such as mineral classification and desliming. However, current technologies have not specifically applied hydrocyclones to the pretreatment process of red mud iron ore beneficiation. Introducing hydrocyclones into the red mud iron ore beneficiation process, through a classification method that removes fine particles and retains coarse ones, could address the problems of excessively fine and widely distributed red mud particles. This could potentially improve the magnetic separation environment from the source and significantly enhance the extraction efficiency of iron resources from red mud. Therefore, we propose a method for improving the efficiency of red mud iron ore beneficiation using hydrocyclone classification. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for improving the iron ore beneficiation efficiency of red mud by using hydrocyclones for grading, thus solving the problems mentioned in the background.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for improving the iron separation efficiency of red mud using hydrocyclones includes the following steps: S1. The bottom flow red mud slurry from the final washing settling tank of the alumina plant is transported to the red mud mixing tank and mixed to form a qualified slurry with uniform concentration. S2. The qualified slurry is fed into a hydrocyclone by a feed pump for particle size classification to obtain coarse underflow product and fine overflow product. The underflow product has a high degree of liberation of iron minerals or coarse intergrowth with gangue. The overflow product consists of fine particles that interfere with magnetic separation. S3. The underflow product is directly fed to a magnetic separator for magnetic separation to obtain iron concentrate and magnetic tailings respectively; S4. The overflow product is transported to a tailings thickener for concentration, and the concentrated overflow slurry is transported to a red mud filter press for filter press treatment.

[0007] Furthermore, in step S1, the mass concentration of the qualified slurry is controlled at 10%-30%.

[0008] Furthermore, in step S2, the material separation particle size of the hydrocyclone is precisely controlled within 15-20 μm by adjusting the inlet pressure parameter of the hydrocyclone.

[0009] Furthermore, the inlet pressure adjustment range of the hydrocyclone is 0.12MPa-0.14MPa.

[0010] Furthermore, in step S3, the magnetic separation equipment is a high gradient magnetic separator, and the underflow product achieves efficient separation of iron minerals and gangue through the high gradient magnetic separator.

[0011] Furthermore, the background field strength of the high gradient magnetic separator is 1.3T, and the magnetic separation adopts a coarse-fine separation process.

[0012] Furthermore, the red mud to be treated has a total iron (TFe) content of ≥32%, and the proportion of -10μm particle size in the red mud is ≥60%. The total iron (TFe) content of the underflow product after hydrocyclone classification is 34%-36%.

[0013] Furthermore, in step S4, after the overflow product is concentrated by the tailings thickener, the mass concentration of the slurry is controlled at 30%, and the clear liquid generated during the concentration process is recycled to the red mud mixing tank for slurry blending.

[0014] This invention provides a method for improving the iron removal efficiency of red mud using hydrocyclones for classification. Compared with existing technologies, it has the following advantages: 1. This invention removes or separates fine-grained ore slime that seriously interferes with magnetic separation by using a hydrocyclone in advance, thereby reducing the viscosity of the slurry from the source and effectively avoiding the occurrence of magnetic agglomeration and non-magnetic entrainment during magnetic separation. This creates a good separation environment for magnetic separation. After implementation, the grade of iron concentrate can be improved, the iron recovery rate can be improved, and the technical and economic indicators of red mud iron beneficiation can be greatly improved. 2. The hydrocyclone's classification function enables the coarse-particle underflow product to achieve an initial enrichment of 34%-36% of total iron (TFe). Subsequent magnetic separation further improves the iron concentrate production efficiency by separating the enriched slurry. 3. Differentiated processing technology is adopted for the coarse and fine particle products after classification. The coarse particle underflow is separated into coarse and fine particles by a high gradient magnetic separator with a background field strength of 1.3T. The fine particle overflow is directly concentrated and filtered, which realizes the optimized matching of process and material characteristics and improves the grade of iron concentrate in the coarse particle part. 4. The clear liquid generated during the thickening process of the tailings thickener is recycled to the red mud mixing tank for slurry preparation, which reduces the consumption of fresh water and realizes the recycling of water resources. At the same time, the present invention uses a hydrocyclone as the core pretreatment equipment. The equipment is mature, the investment cost is low, and the energy consumption and operating cost during operation are controllable, which further reduces the overall cost of red mud iron ore beneficiation. 5. The supporting system of this invention adopts a hydrocyclone group with multiple hydrocyclones connected in parallel, which can meet the needs of large-scale and continuous treatment of red mud in alumina plants; at the same time, it is equipped with a programmable logic control unit to realize real-time acquisition and precise control of the entire process operation parameters, reduce the intensity of manual operation, and improve the stability and reliability of system operation. 6. The method of the present invention has few steps, smooth connection between each process, and reasonable equipment layout of the supporting system. It does not require large-scale transformation of the existing red mud iron ore beneficiation production line, and is easy to promote and apply in the existing red mud iron ore beneficiation production line of alumina plant, and has good industrial application prospects. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the main structure of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The red mud raw materials used in the embodiments of this invention are all from the bottom flow red mud of the final washing settling tank of an alumina plant. All the equipment used are conventional and mature equipment in the mining and smelting fields. Among them, the background field strength of the high gradient magnetic separator can be precisely controlled up to 1.3T, the hydrocyclone can achieve inlet pressure control of 0.12MPa-0.14MPa through the inlet pressure regulating valve, the tailings thickener can achieve slurry concentration up to 30%, and the control unit is a programmable logic control unit (PLC) that can realize real-time acquisition and control of the operating parameters of each device.

[0018] Example 1 A method for improving iron removal efficiency from red mud using hydrocyclones, wherein the total iron (TFe) content of the treated red mud raw material is 32%, of which -10μm particles account for 61%, is described in the following steps: Slurry preparation: The above-mentioned red mud raw materials are transported to the red mud mixing tank, the stirring device is turned on to mix them evenly, and a qualified slurry with a mass concentration of 20% is prepared. Hydraulic classification: Qualified slurry is fed to the hydrocyclone group at an inlet pressure of 0.14 MPa by a feed pump for particle size classification. At this time, the separation particle size of the hydrocyclone is controlled at 15-20 μm. After classification, coarse particle underflow product and fine particle overflow product are obtained. The total iron (TFe) content of the underflow product is 36%. Magnetic separation: The underflow product is directly fed to a high gradient magnetic separator, and magnetic separation is carried out using a coarse-fine separation process under a background field strength of 1.3T to obtain iron concentrate and magnetic tailings respectively. Overflow treatment: The overflow product is transported to the tailings thickener for concentration treatment, and the overflow slurry is concentrated to a mass concentration of 30%. The clear liquid generated during the concentration process is recycled to the red mud mixing tank for slurry preparation. The concentrated overflow slurry is transported to the red mud filter press for filter press treatment.

[0019] In this embodiment, the final grade of the separated iron concentrate reached 53%, and the iron recovery rate reached 30.0%. Compared with the existing direct magnetic separation process, the iron concentrate grade and iron recovery rate were increased by 2 percentage points.

[0020] Example 2 A method for improving iron beneficiation efficiency of red mud using hydrocyclones for classification, wherein the red mud raw material is the same as that in Example 1, with a total iron (TFe) content of 32% and a -10μm particle size ratio of 61%, is described in the following steps: Slurry preparation: The red mud raw material is transported to the red mud mixing tank, stirred and mixed evenly to form a qualified slurry with a mass concentration of 20%; Hydraulic classification: Qualified slurry is fed to the hydrocyclone group at an inlet pressure of 0.12MPa by a feed pump for particle size classification. The separation particle size of the hydrocyclone is controlled at 15-20μm. After classification, coarse underflow product and fine overflow product are obtained. The total iron (TFe) content of the underflow product is 34%, realizing the further recovery of ultrafine iron resources. Magnetic separation: The underflow product is directly fed to a high gradient magnetic separator, and magnetic separation is carried out using a coarse-fine separation process under a background field strength of 1.3T to obtain iron concentrate and magnetic tailings respectively. Overflow treatment: The overflow product is transported to the tailings thickener for concentration treatment. After concentration to 30% by mass, the clear liquid is recycled to the red mud mixing tank. The concentrated overflow slurry is transported to the red mud filter press for filter press treatment.

[0021] In this embodiment, the final grade of the separated iron concentrate reached 52%, and the iron recovery rate reached 32.89%. Compared with the existing direct magnetic separation process, the iron concentrate grade was increased by 1 percentage point and the iron recovery rate was increased by 4.89 percentage points, achieving a significant improvement in iron recovery rate.

[0022] Example 3 A system for improving the iron ore beneficiation efficiency of red mud using hydrocyclones for classification, used to implement the methods of Examples 1 and 2, includes a red mud mixing tank, a feed pump, a hydrocyclone group, a high-gradient magnetic separator, a tailings thickener, a red mud filter press, a control unit, and supporting pipelines and pumps / valve. The hydrocyclone group consists of three hydrocyclones connected in parallel, adapted to the slurry processing volume of industrial continuous production. The control unit is a PLC (Programmable Logic Controller), electrically connected to the feed pump, the hydrocyclone group, the high-gradient magnetic separator, and the tailings thickener, respectively. It can collect the delivery pressure of the feed pump, the inlet pressure of the hydrocyclone group, the magnetic field strength of the high-gradient magnetic separator, and the slurry concentration of the tailings thickener in real time, and make precise adjustments according to production needs. The tailings thickener is equipped with a clear liquid outlet, which is connected to the feed inlet of the red mud mixing tank to realize the recycling of the concentrated clear liquid. Pumps / valve are installed on the pipelines connected to each device for controlling the on / off of the slurry, flow rate adjustment, and pressure regulation.

[0023] During the operation of the system in this embodiment, the various devices are smoothly connected and the parameters are precisely controlled. It can realize continuous production throughout the entire process of red mud iron ore pretreatment, magnetic separation and overflow treatment. It has high operational stability and low manual operation intensity, making it suitable for large-scale application in alumina plants.

[0024] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0025] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for improving the efficiency of iron separation from red mud by using a hydrocyclone classifier, characterized in that, Includes the following steps: S1. The bottom flow red mud slurry from the final washing settling tank of the alumina plant is transported to the red mud mixing tank and mixed to form a qualified slurry with uniform concentration. S2. The qualified slurry is fed into a hydrocyclone by a feed pump for particle size classification to obtain coarse underflow product and fine overflow product. The underflow product has a high degree of liberation of iron minerals or coarse intergrowth with gangue. The overflow product consists of fine particles that interfere with magnetic separation. S3. The underflow product is directly fed to a magnetic separator for magnetic separation to obtain iron concentrate and magnetic tailings respectively; S4. The overflow product is transported to a tailings thickener for concentration, and the concentrated overflow slurry is transported to a red mud filter press for filter press treatment.

2. The method for improving the iron ore beneficiation efficiency of red mud using hydrocyclones according to claim 1, characterized in that, The mass concentration of the qualified slurry in step S1 is controlled between 10% and 30%.

3. The method for improving the iron ore beneficiation efficiency of red mud using hydrocyclones according to claim 2, characterized in that, In step S2, the material separation particle size of the hydrocyclone is precisely controlled within 15-20μm by adjusting the inlet pressure parameter of the hydrocyclone.

4. A method for improving the iron ore beneficiation efficiency of red mud using hydrocyclones according to claim 3, characterized in that, The inlet pressure adjustment range of the hydrocyclone is 0.12MPa-0.14MPa.

5. A method for improving the iron ore beneficiation efficiency of red mud using hydrocyclones according to claim 4, characterized in that, The magnetic separation equipment mentioned in step S3 is a high gradient magnetic separator, and the underflow product achieves efficient separation of iron minerals and gangue through the high gradient magnetic separator.

6. A method for improving the iron ore beneficiation efficiency of red mud using hydrocyclones according to claim 5, characterized in that, The background field strength of the high gradient magnetic separator is 1.3T, and the magnetic separation adopts a coarse-fine separation process.

7. A method for improving the iron ore beneficiation efficiency of red mud using a hydrocyclone for classification according to claim 6, characterized in that, The total iron (TFe) content of the red mud to be treated is ≥32%, and the proportion of -10μm particles in the red mud is ≥60%. The total iron (TFe) content of the underflow product after hydrocyclone classification is 34%-36%.

8. A method for improving the iron ore beneficiation efficiency of red mud using hydrocyclones according to claim 7, characterized in that, The overflow product described in step S4 is concentrated by the tailings thickener, and the mass concentration of the slurry is controlled at 30%. The clear liquid generated during the concentration process is recycled to the red mud mixing tank for slurry blending.

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