A method of gravity separation for the beneficiation of ilmenite
By classifying ilmenite by particle size and designing differentiated spiral sluices, the problem of poor separation effect of ilmenite of different particle sizes in the existing technology has been solved, and efficient ilmenite separation and resource utilization have been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHEASTERN UNIV CHINA
- Filing Date
- 2026-04-24
- Publication Date
- 2026-05-29
AI Technical Summary
In the existing technology, the spiral chute fails to set appropriate sorting conditions according to the differences in particle size during the ilmenite sorting process, resulting in low sorting efficiency, easy loss of fine-grained heavy minerals, insufficient recovery of coarse-grained minerals, and unsatisfactory overall sorting effect.
Ilmenite is divided into coarse and fine grades according to particle size. Different pitch-to-diameter ratios of spiral chutes are designed for each grade, and the radial position of the cutter is adjusted to achieve precise matching between structural parameters and material characteristics, ensuring that each grade is sorted under optimal flow field conditions.
It significantly improves the sorting efficiency and concentrate quality of ilmenite, reduces the load on subsequent processing steps, simplifies the process flow, and enhances the utilization rate of titanium resources.
Smart Images
Figure CN122098798A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of mineral processing technology, and in particular to a method for classifying and re-separating ilmenite. Background Technology
[0002] Ilmenite is an important titanium-bearing mineral resource for the production of titanium dioxide, sponge titanium, and titanium alloys. As high-grade, easily beneficiated ilmenite resources gradually decrease, the demand for developing and utilizing low-grade, fine-grained, and complex-composition ilmenite resources continues to grow. Therefore, how to effectively enrich ilmenite during the beneficiation process has become a key technical issue for improving the utilization rate of titanium resources.
[0003] In the separation and enrichment process of ilmenite, spiral sluices, as a typical gravity separation device, are widely used in ilmenite preparation processes due to their advantages such as simple structure, large processing capacity, stable operation, and low cost. Spiral sluices typically undertake the task of enriching heavy minerals in raw ore or intermediate products. Their separation effect not only directly determines the recovery rate and concentrate grade of this process stage, but also significantly impacts the feed quality and processing load of subsequent flotation and electrostatic separation operations. Therefore, spiral sluices play a crucial role in the ilmenite preparation process and are one of the core components affecting the overall enrichment effect.
[0004] From the perspective of the separation mechanism, when using spiral sluices for ilmenite separation, the ore particles are subjected to a combination of forces, including gravity, centrifugal force, fluid drag, and surface friction, in the flow field on the sluice surface, resulting in particle stratification and radial banding. Particles with different properties are distributed in different areas along the sluice surface, and are ultimately intercepted and recovered by cutters according to their respective areas to obtain concentrate and tailings products. However, in existing technologies for ilmenite separation using spiral sluices, the feed is usually treated as a whole material. That is, without particle size classification, the entire particle size distribution is directly fed into the spiral sluice and separation is completed under uniform process conditions. In other words, existing technologies generally do not set corresponding separation conditions for the differences in separation behavior of different particle sizes in the feed, but rather treat particles with significantly different particle size distributions as a unified object for overall separation, which to some extent limits the improvement of separation efficiency.
[0005] Among the structural parameters of spiral chutes, the screw pitch is one of the key factors affecting the separation effect. The screw pitch not only determines the unfolding of the flow field on the chute surface and the slurry flow state, but also further affects the residence time of particles on the chute surface, the radial migration path, the location of the zone boundary, and the width of the enrichment zone, thus directly impacting concentrate yield, concentrate grade, and target mineral recovery. However, existing technologies typically use spiral chutes with a fixed screw pitch to separate ilmenite feed. That is, after selecting a certain screw pitch, the separation index is optimized by adjusting operating parameters such as feed concentration, feed flow rate, and the radial position of the cutter. This method of adjusting fixed structural parameters in conjunction with operating parameters is difficult to adapt to the differentiated requirements of different particle sizes for screw pitch and other structural parameters, failing to fully realize the potential efficiency of spiral chutes in ilmenite separation.
[0006] Current technologies for ilmenite separation using spiral chute systems typically treat the entire feed size as a whole, without setting separate separation conditions based on the inherent differences in the separation behavior of different particle sizes. In reality, the proportions of gravity, centrifugal force, fluid drag, and surface friction experienced by coarse and fine particles in the spiral chute flow field differ significantly, resulting in variations in their trajectories, stratification velocities, radial migration distances, and enrichment zone locations. Mixing particles with significantly different size compositions inevitably leads to mutual interference during separation. Fine-grained heavy minerals are easily entrained by coarse-grained light minerals or slime and lost in the tailings, while coarse-grained heavy minerals may settle too quickly and fail to migrate sufficiently radially to the concentrate enrichment zone, thus affecting overall separation efficiency and concentrate quality.
[0007] Meanwhile, the fixed pitch means the separation flow field conditions are rigid, making it impossible to make structural adjustments to accommodate changes in the particle size distribution of the feed or differences in the separation characteristics of different particle sizes. This results in a poor match between the equipment's separation performance and the particle size characteristics of the feed. This mismatch between structural parameters and material characteristics means that the spiral chute cannot provide a flow field environment suitable for the separation behavior of each particle size during actual operation. The loosening, stratification, and radial migration of particles on the chute surface are difficult to achieve ideal conditions, and the mutual interference between different particle sizes is further aggravated, thus restricting the improvement of separation efficiency and concentrate quality. Even by optimizing operating parameters such as feed concentration, feed flow rate, and cutter position, it is difficult to fundamentally compensate for the adaptability limitations caused by fixed structural parameters. When the particle size distribution of the feed fluctuates, the stability and reliability of the separation effect cannot be effectively guaranteed.
[0008] Due to the aforementioned technical limitations, existing spiral sluice gate separation technologies for ilmenite often face a trade-off in actual production: if the screw pitch and separation parameters are set primarily for coarse-grained recovery, the recovery rate of fine-grained heavy minerals is low; conversely, if parameters are adjusted to balance fine-grained recovery, the coarse-grained separation effect decreases. This contradiction makes it difficult for a single spiral sluice gate to achieve efficient recovery of both coarse and fine-grained particles simultaneously. Ilmenite resources in some particle sizes are not fully enriched, increasing the feeding burden and processing difficulty of subsequent flotation and electrostatic separation operations, ultimately hindering the overall improvement of titanium resource utilization. Summary of the Invention
[0009] The purpose of this invention is to provide a classification and gravity separation method for ilmenite, in order to solve the problems of low separation accuracy, unsatisfactory concentrate upgrading effect, and easy loss of high-grade particles in tailings when using uniform separation conditions for ilmenite of different particle sizes.
[0010] The technical solution adopted in this invention is as follows:
[0011] The present invention proposes a method for the classification and gravity separation of ilmenite, the method comprising the following steps: Step 1: Separate the ilmenite feed into two different particle sizes: coarse-grained ilmenite and fine-grained ilmenite. Step 2: Design spiral chutes with corresponding pitch-to-diameter ratios for the two particle size materials respectively, and feed the different particle sizes of ilmenite into the spiral chutes with differentiated pitch-to-diameter ratios for sorting. Step 3: Adjust the radial position of the cutter of each spiral chute to cut the concentrate in the cutting section and obtain the corresponding tailings; Step 4: Collect the concentrate and tailings corresponding to each particle size of ilmenite to obtain ilmenite concentrate products; Step 5: Based on the sorting results of coarse and fine ilmenite under different distance-to-diameter ratios, determine the distance-to-diameter ratio and cut-off range that match each size of ilmenite.
[0012] Furthermore, in step 1, with 0.15 mm as the grading boundary, the particle size range of coarse-grained ilmenite is -0.5 to +0.15 mm, and the particle size range of fine-grained ilmenite is -0.15 mm.
[0013] Furthermore, in step 2, the pitch-to-diameter ratio of the spiral chute corresponding to coarse-grained ilmenite is 0.7, and the pitch-to-diameter ratio of the spiral chute corresponding to fine-grained ilmenite is 0.5.
[0014] Furthermore, in step 2, the solid mass concentration of both coarse-grained ilmenite and fine-grained ilmenite when fed into the corresponding spiral chute is 20%~30%.
[0015] Furthermore, in step 2, the inlet volumetric flow rate of both coarse-grained ilmenite and fine-grained ilmenite when fed into the corresponding spiral chute is 10~15L / min.
[0016] Furthermore, in step 3, the radial position of the ore cutter is set starting 70mm from the center axis of the spiral chute.
[0017] Furthermore, in step 3, the ore cutter moves outward by 10mm each time, and the radial position gradually moves outward from 70mm to 140mm.
[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention pre-classifies ilmenite ore samples into two particle sizes, fully considering the inherent differences in the stress characteristics of coarse and fine particles. This effectively avoids mutual interference between different particle sizes during the sorting process and eliminates the problems of fine heavy minerals being carried away by coarse light minerals or sludge, as well as coarse heavy minerals failing to migrate radially to the concentrate enrichment area due to excessively rapid settling.
[0019] Based on this, the present invention designs corresponding pitch-to-diameter ratios for different particle sizes, achieving a precise match between structural parameters and material characteristics. Specifically, a larger pitch-to-diameter ratio is used for coarse particles to ensure sufficient flow velocity and centrifugal effect in the slurry, while a smaller pitch-to-diameter ratio is used for fine particles to reduce slurry flow velocity and extend residence time. This allows materials of each particle size to complete stratification, separation, and sorting under optimal fluid medium conditions, overcoming the defect that the single pitch used in the existing technology cannot simultaneously meet the sorting requirements of different particle sizes, and effectively solving the technical problem of "choosing one over the other".
[0020] Furthermore, this invention combines grading with a differential pitch-to-diameter ratio design, significantly improving the spiral chute's adaptability to fluctuations in feed particle size distribution. It allows for flexible adjustment of the grading particle size and the corresponding screw pitch parameters for each size class based on material characteristics, ensuring the separation flow field always maintains a good match with the feed characteristics. Compared to existing technologies that can only be optimized by adjusting operating parameters, this invention solves the separation adaptability problem from a structural differentiation design perspective, ensuring excellent and stable separation performance under different operating conditions.
[0021] Ultimately, this invention can ensure the effective recovery of coarse and fine particles in the gravity separation stage, significantly reducing the load on subsequent flotation, electrostatic separation and other operations, helping to simplify the length of the ilmenite combined process, and improving the overall economy and environmental friendliness of the physical separation process. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the process for a classification and re-separation method for ilmenite proposed in this invention. Figure 2This is a schematic diagram of the small pitch-to-diameter ratio spiral chute and the large pitch-to-diameter ratio spiral chute in this invention; Figure 3 This is a schematic diagram showing the radial position of the ore cutter in this invention; Figure 4 A schematic diagram showing the yield variation of coarse-grained ilmenite under different aspect ratios; Figure 5 A schematic diagram showing the variation of TiO2 grade in coarse-grained ilmenite under different aspect ratios; Figure 6 A schematic diagram showing the TiO2 recovery rate of coarse-grained ilmenite under different aspect ratios; Figure 7 A schematic diagram showing the yield variation of fine-grained ilmenite under different aspect ratios; Figure 8 A schematic diagram showing the variation of TiO2 grade in fine-grained ilmenite under different aspect ratios; Figure 9 This is a schematic diagram showing the TiO2 recovery rate of fine-grained ilmenite under different aspect ratios. Detailed Implementation
[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] It should be noted that in the description of this invention, the terms "upper", "lower", "top", "bottom", "one side", "the other side", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not mean that the device or element must have a specific orientation, or be constructed and operated in a specific orientation.
[0025] See appendix Figure 1 The present invention proposes a method for classifying and re-separating ilmenite, comprising the following steps: Step 1: Separate the ilmenite feed into two different particle sizes: coarse-grained ilmenite and fine-grained ilmenite. The grading standards are as follows: with 0.15 mm as the boundary for particle size classification, the particle size range of coarse-grained ilmenite is -0.5 to +0.15 mm, and the particle size range of fine-grained ilmenite is -0.15 mm.
[0026] Step 2: Design spiral chutes with corresponding pitch-to-diameter ratios for the two particle size materials respectively, and feed the different particle sizes of ilmenite into the spiral chutes with differentiated pitch-to-diameter ratios for sorting. The spiral chute with differentiated pitch-to-diameter ratio design includes a small pitch-to-diameter ratio spiral chute and a large pitch-to-diameter ratio spiral chute, and the pitch-to-diameter ratio parameters of the small pitch-to-diameter ratio spiral chute and the large pitch-to-diameter ratio spiral chute are different. Among them, the small-pitch-to-diameter ratio spiral chute has a pitch-to-diameter ratio of 0.5 and is used for sorting fine-grained ilmenite; the large-pitch-to-diameter ratio spiral chute has a pitch-to-diameter ratio of 0.7 and is used for sorting coarse-grained ilmenite; the two spiral chute structures are as follows: Figure 2 As shown in the figure, other structural parameters are shown in Table 1.
[0027] Table 1. Structural parameters of the spiral chute
[0028] The solid mass concentration of both the coarse-grained and fine-grained ilmenite fed into the spiral chute is 20% to 30%, preferably 25%. The inlet volumetric flow rate of both coarse-grained ilmenite and fine-grained ilmenite when fed into the spiral chute is 10~15L / min, preferably 12L / min.
[0029] Step 3: Adjust the radial position of the cutter of each spiral chute to cut the concentrate in the cutting section and obtain the corresponding tailings; The cutting section is controlled by adjusting the radial position of the ore cutter; In this embodiment, the radial position of the ore cutter is initially set 70mm from the central axis of the spiral chute equipment. The ore cutter moves outward by 10mm each time, gradually increasing its radial position from 70mm to 140mm; that is, the radial positions of the ore cutter are successively 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, and 140mm. The radial positions of the ore cutter are as follows: Figure 3 As shown.
[0030] Step 4: Collect the concentrate and tailings corresponding to each particle size of ilmenite to obtain ilmenite concentrate products.
[0031] The concentrate yield, tailings yield, and TiO2 recovery rate are calculated based on the dry ore quality and TiO2 grade of the concentrate and tailings.
[0032] Step 5: Based on the sorting results of coarse and fine ilmenite under different distance-to-diameter ratios, determine the distance-to-diameter ratio and cut-off range that match each size of ilmenite.
[0033] Coarse-grained ilmenite was separated using spiral chutes with a pitch-to-diameter ratio of 0.5 and 0.7, respectively. The concentrate yield, tailings yield, concentrate TiO2 grade, tailings TiO2 grade, concentrate TiO2 recovery rate, and tailings TiO2 recovery rate were compared under different pitch-to-diameter ratios. The results are as follows: Figures 4-6 As shown.
[0034] Depend on Figures 4-6 It can be seen that for coarse-grained ilmenite, there are significant differences in the sorting response between the two aspect ratios. Compared to a diameter-to-concentration ratio of 0.7, although the overall concentrate yield and TiO2 recovery rate are higher at a diameter-to-concentration ratio of 0.5, the TiO2 grade of the concentrate remains at 5.91% to 6.51% in the 70-100mm range, only slightly higher than the original ore grade of 5.90%. Subsequently, it drops to 5.20% and 4.73% in the 110-120mm range, and rebounds to 5.30% and 5.75% in the 130-140mm range. This indicates that the radial distribution of this size of ilmenite on the trough surface is not an ideal sharp zoning, but rather has a certain width of transitional mixing zone. Therefore, as the radial position of the cutter moves outward, some high-grade particles and low-grade particles are redistributed in different radial ranges, resulting in low-grade particles being mixed into the concentrate and high-grade particles being retained in the tailings. Especially at 120mm, the TiO2 grade of the tailings is as high as 62.01%, with obvious high-grade particle retention, and the selectivity of the zoning interface is significantly reduced. Conversely, with a diameter-to-spacing ratio of 0.7, the TiO2 grade of the concentrate in the 70-90 mm range remained at 12.16%-15.27%, significantly higher than the 5.90% of the original ore. This enhanced the local enrichment of high-grade particles on the inner side of the chute, resulting in a high-grade concentrate. Although the TiO2 grade of the tailings also gradually increased as the cutter moved outward, it remained far lower than when the diameter-to-spacing ratio was 0.5. In summary, a larger diameter-to-spacing ratio spiral chute is more suitable for the separation of coarse-grained ilmenite, and a better balance between upgrading and recovery is achieved when the radial position of the cutter is between 70-100 mm.
[0035] Fine-grained ilmenite was separated using spiral chutes with a pitch-to-diameter ratio of 0.5 and 0.7, respectively. The concentrate yield, tailings yield, concentrate TiO2 grade, tailings TiO2 grade, concentrate TiO2 recovery rate, and tailings TiO2 recovery rate were compared under different pitch-to-diameter ratios. The results are as follows: Figures 7-9 As shown.
[0036] Depend on Figures 7-9It can be seen that for fine-grained ilmenite, the concentrate yield and TiO2 recovery rate under a diameter-to-spacing ratio of 0.5 are generally higher than those under 0.7. Simultaneously, the TiO2 grade of the concentrate under a diameter-to-spacing ratio of 0.5 is also generally higher than that under 0.7, indicating that it not only increases the proportion of fine-grained target minerals entering the concentrate but also maintains relatively good recovery and upgrading effects over a wider radial range. In contrast, the concentrate separation index generally decreases under a diameter-to-spacing ratio of 0.7. More notably, the TiO2 grade of the tailings generally increases, reaching 30.96% at 140 mm, significantly higher than the grades of the original ore and the concentrate at the same time. This result indicates that under this condition, fine-grained ilmenite is significantly affected by fluid drag and outward migration, forming a distinct fine-grained heavy mineral mismatch enrichment zone in the outer tailings, causing the tailings to no longer correspond to normally depleted products. Overall, for fine-grained ilmenite, a diameter-to-spacing ratio of 0.5 exhibits superior comprehensive separation performance compared to 0.7. In summary, spiral chutes with a smaller pitch-to-diameter ratio are more suitable for the separation of fine-grained ilmenite, and when the radial position of the cutter is 70-90 mm, a better balance is achieved between upgrading and recovery.
[0037] This invention utilizes a systematic sorting method to optimally determine the matching scheme between different particle sizes of ilmenite and the parameters of the spiral chute. As shown in Table 2, for coarse-grained ilmenite (-0.5 to +0.15 mm), a spiral chute with a pitch-to-diameter ratio of 0.7, combined with a radial interception zone of 70–100 mm, effectively enhances the loosening and stratification of coarse particles; for fine-grained ilmenite (-0.15 mm), a spiral chute with a pitch-to-diameter ratio of 0.5, combined with a radial interception zone of 70–90 m, is beneficial for stabilizing the flow field and prolonging the settling time of fine particles.
[0038] Table 2 Optimal sorting parameters for ilmenite of different particle sizes
[0039] Matters not covered in this invention are common knowledge.
[0040] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A method for classifying and re-separating ilmenite, characterized in that, The method includes the following steps: Step 1: Separate the ilmenite feed into two different particle sizes: coarse-grained ilmenite and fine-grained ilmenite. Step 2: Design spiral chutes with corresponding pitch-to-diameter ratios for the two particle size materials respectively, and feed the different particle sizes of ilmenite into the spiral chutes with differentiated pitch-to-diameter ratios for sorting. Step 3: Adjust the radial position of the cutter of each spiral chute to cut the concentrate in the cutting section and obtain the corresponding tailings; Step 4: Collect the concentrate and tailings corresponding to each particle size of ilmenite to obtain ilmenite concentrate products; Step 5: Based on the sorting results of coarse and fine ilmenite under different distance-to-diameter ratios, determine the distance-to-diameter ratio and cut-off range that match each size of ilmenite.
2. The method for classifying and re-separating ilmenite according to claim 1, characterized in that: In step 1, 0.15 mm is used as the grading boundary. The particle size range of coarse-grained ilmenite is -0.5 to +0.15 mm, and the particle size range of fine-grained ilmenite is -0.15 mm.
3. The method for classifying and re-separating ilmenite according to claim 1, characterized in that: In step 2, the pitch-to-diameter ratio of the spiral chute corresponding to coarse-grained ilmenite is 0.7, and the pitch-to-diameter ratio of the spiral chute corresponding to fine-grained ilmenite is 0.
5.
4. The method for classifying and re-separating ilmenite according to claim 1, characterized in that: In step 2, the solid mass concentration of both coarse-grained ilmenite and fine-grained ilmenite when fed into the corresponding spiral chute is 20%~30%.
5. The method for classifying and re-separating ilmenite according to claim 1, characterized in that: In step 2, the inlet volumetric flow rate of both coarse-grained ilmenite and fine-grained ilmenite when fed into the corresponding spiral chute is 10~15L / min.
6. The method for classifying and re-separating ilmenite according to claim 1, characterized in that: In step 3, the radial position of the ore cutter is set starting from 70mm away from the central axis of the spiral chute.
7. The method for classifying and re-separating ilmenite according to claim 6, characterized in that: In step 3, the cutter moves outward by 10mm each time, and the radial position gradually moves outward from 70mm to 140mm.