Closed-loop reselection process and system for recovering ilmenite from strong magnetic tailings

Abstract

The invention relates to the technical field of mineral processing, in particular to a closed-loop reselection process and system for recovering ilmenite from strong magnetic tailings. According to the invention, strong magnetic tailings are creatively intercepted after coarse grain strong magnetic scavenging operation of a main process, and are guided to enter a set of independent and closed-circuit gravity separation system. According to the system, ilmenite is recycled through gravity separation, internal efficient closed-loop circulation is achieved through middling returning and size grading control, and the titanium metal recycling rate and the concentrate quality are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, specifically to a closed-circuit gravity separation process and system for recovering ilmenite from strongly magnetic tailings. Background Technology

[0002] In the beneficiation process of ilmenite, high-intensity magnetic separation is a crucial pre-enrichment step. In some existing technologies, after the iron ore tailings undergo "high-intensity magnetic roughing" to remove most of the strongly magnetic minerals, the tailings are then recovered through "coarse-grained high-intensity magnetic roughing scavenging." However, in existing technologies, the tailings after "coarse-grained high-intensity magnetic scavenging" (i.e., "high-intensity magnetic tailings") are directly discarded as the final tailings.

[0003] This portion of "strong magnetic tailings" still contains a large amount of ilmenite that could not be effectively captured by strong magnetic separation due to its intergrowth, fine-grained dispersion, or weak magnetism. Since strong magnetic separation mainly relies on differences in mineral magnetic properties, its recovery capacity for ilmenite in the above-mentioned forms is limited. This results in a large loss of these valuable minerals with the tailings, causing significant resource waste and hindering the improvement of the overall titanium metal recovery rate.

[0004] Currently, the industry lacks an effective technology for the specialized and efficient recovery of ilmenite from these "waste" strong magnetic tailings. Simply extending or modifying the existing strong magnetic flotation main process often results in complex processes, high investment costs, and potential disruption to the stable operation of the main system. Therefore, how to economically and efficiently recover valuable ilmenite from strong magnetic tailings without affecting the main process has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] In view of this, the present invention proposes a closed-circuit gravity separation process and system for recovering ilmenite from strongly magnetic tailings. It innovatively intercepts the strongly magnetic tailings after the "coarse-grained strongly magnetic scavenging" operation in the main process and guides them into an independent, closed-circuit gravity separation system. This at least solves the problems of complex methods and processes and high investment costs associated with recovering ilmenite from strongly magnetic tailings in existing systems.

[0006] The first aspect of this invention proposes a closed-circuit gravity separation process for recovering ilmenite from strong magnetic tailings, comprising the following steps: intercepting tailings discharged after the coarse-grained strong magnetic roughing and scavenging operation in the main process; subjecting the tailings to gravity roughing to obtain roughing concentrate and roughing tailings; subjecting the roughing concentrate to gravity cleaning to obtain gravity titanium concentrate; subjecting the roughing tailings to gravity scavenging to obtain scavenging concentrate and final tailings; and returning the scavenging concentrate to the feed end of the gravity cleaning operation to form an internal closed-circuit cycle. The gravity roughing, gravity cleaning, and / or gravity scavenging are performed using spiral chute or shaking table. In some embodiments, the main process is a combined magnetic-flotation separation process for ilmenite, which includes at least the following operations performed in sequence: strong magnetic separation, coarse strong magnetic roughing, coarse strong magnetic roughing scavenging, classification and regrinding, coarse two-stage de-ironization, coarse strong magnetic cleaning, and coarse flotation; and the tailings generated from the coarse strong magnetic roughing scavenging operation and / or the coarse strong magnetic cleaning operation are transported to a tailings thickening device for processing.

[0007] In some embodiments, the closed-circuit gravity separation process for recovering ilmenite from strongly magnetic tailings prior to gravity roughing further includes: concentrating the intercepted tailings to a slurry mass concentration of 40% to 60%.

[0008] In some embodiments, the closed-circuit gravity separation process for recovering ilmenite from strongly magnetic tailings further includes classifying the gravity-separated titanium concentrate, with the undersize as the final product and the oversize returned to the regrinding operation of the main process for regrinding.

[0009] In some embodiments, grading is performed using a high-frequency fine sieve with a sieve aperture size of 0.074 mm to 0.15 mm.

[0010] In some embodiments, the regrinded product is selectively returned to the re-selection and cleaning operation feed end or the grading operation feed end of the main process, depending on its particle size distribution.

[0011] In some embodiments, reselection scanning includes at least two cascaded scanning operations; and / or, reselection selection includes at least two cascaded selection operations.

[0012] A second aspect of the present invention provides a closed-circuit gravity separation system for recovering ilmenite from strong magnetic tailings, for implementing the above-mentioned process, comprising: a gravity roughing device, the inlet of which is connected to the tailings outlet of the coarse-grained strong magnetic roughing and scavenging device in the main process; a gravity cleaning device, the inlet of which is connected to the concentrate outlet of the gravity roughing device; a gravity scavenging device, the inlet of which is connected to the tailings outlet of the gravity roughing device; and the concentrate outlet of the gravity scavenging device is connected to the feed end of the gravity cleaning device via a pipeline.

[0013] In some embodiments, a closed-circuit gravity separation system for recovering ilmenite from strongly magnetic tailings further includes a gravity thickener located before the gravity roughing unit.

[0014] In some embodiments, the closed-circuit gravity separation system for recovering ilmenite from strong magnetic tailings further includes a high-frequency fine screening device, the feed inlet of which is connected to the concentrate outlet of the gravity separation and cleaning device, the undersize outlet of which is the product outlet, and the oversize outlet of which is connected to the feed inlet of the regrinding operation of the main process.

[0015] Compared with the prior art, the closed-circuit gravity separation process and system for recovering ilmenite from strongly magnetic tailings provided by the present invention have at least the following beneficial effects: 1. Pioneering a new path for tailings recovery and improving the overall recovery rate: This invention is the first to use "coarse-grained strong magnetic scavenging" tailings, a traditional waste, as the target raw material and recovers it through an independent gravity separation system. It effectively recovers ilmenite that cannot be captured by strong magnetic separation, and is expected to increase the overall titanium metal recovery rate of the plant by 3-8%, and ultimately reduce the TiO2 grade in the tailings by 1-2%.

[0016] 2. Closed-loop internal system for gravity separation, high recovery rate and stable operation: By returning the concentrate (mid-minerals) from the scavenging stage to the cleaning stage, a highly efficient closed-loop circulation is formed. This design avoids the risk of recoverable minerals being lost as tailings in the scavenging stage, enabling the system to more thoroughly recover useful minerals and improving separation efficiency and operational stability.

[0017] 3. The system operates independently and in parallel, and the transformation is simple: The gravity separation and recovery system runs in parallel with the main process, and only extracts tailings after the "coarse-grained strong magnetic scavenging". It has minimal interference with the production of the main process, making it very suitable for existing concentrators to carry out technical transformation in a modular way. It requires less investment, yields quick results, and operates independently. Attached Figure Description

[0018] 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 only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of the main workflow of an embodiment of the present invention; Figure 2 This is a flowchart of a closed-circuit gravity separation process for recovering ilmenite from strongly magnetic tailings according to an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "connection" and "communication" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a fluid connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] In the following embodiments, "main process" refers to the main process of ilmenite beneficiation using strong magnetic separation as the core technology in this invention, which includes standard operations such as "coarse-grained strong magnetic roughing and scavenging". The starting material of the main process is "first-stage tailings strong magnetic separation iron scavenging tailings". This tailings refers to the final tailings obtained after vanadium-titanium magnetite has undergone a first-stage weak magnetic separation to recover strong magnetic magnetite, followed by strong magnetic separation iron roughing and scavenging operations to maximize the recovery of iron minerals. This tailings has removed most of the strong magnetic minerals (such as magnetite), and the iron mineral content is extremely low. The main components are gangue and ilmenite that was not effectively recovered by strong magnetic separation due to fine-grained dispersion or association with gangue. Figure 1 As shown, the main process is as follows: Strong magnetic pre-enrichment stage: The tailings from the high-intensity magnetic separation iron scavenging process enter the "coarse-grained high-intensity magnetic roughing" stage. This stage initially enriches the ilmenite, yielding a rougher concentrate and rougher tailings. The rougher concentrate enters the subsequent cleaning system, while the rougher tailings enter the "coarse-grained high-intensity magnetic roughing-scavenging" stage to recover residual ilmenite. This stage aims to recover residual ilmenite from the rougher tailings, yielding a scavenging concentrate and scavenging tailings. The scavenging concentrate is returned to the system, while the scavenging tailings (i.e., the "high-intensity magnetic tailings") are concentrated in a "high-intensity magnetic tailings thickener" and then discarded as final tailings. (The scavenging tailings mentioned here are the target material to be recovered in this invention.) Grading, regrinding and particle size control: The roughing concentrate and scavenging concentrate are classified by a titanium hydrocyclone. The fine particles enter subsequent processing, while the coarse particles are regrinded in a two-stage titanium ball mill. The regrinded product is then classified by a high-frequency fine screen. The qualified fine particles enter subsequent processing, while the coarse particles remaining on the screen can be returned to regrinding, forming an internal circulation for particle size control. After classification, the product enters a two-stage coarse particle removal process to further remove residual strongly magnetic iron minerals.

[0023] Coarse-grained strong magnetic separation and product separation: The main product after iron removal (rich in ilmenite and some intergrowths) enters the "coarse-grained high-intensity magnetic separation" process for high-precision magnetic separation. The selected concentrate (ilmenite-rich aggregates) enters the "coarse-grained flotation thickener," and after slurry conditioning, it is fed into the "coarse-grained flotation" process to obtain the final high-grade titanium concentrate. The selected tailings (low-grade tailings) enter the "high-intensity magnetic tailings thickener," and after thickening, they are discarded as final tailings.

[0024] In the strong magnetic beneficiation or preceding stages, byproducts mainly composed of magnetic iron minerals can be separated, forming a "secondary iron concentrate production line." Furthermore, the entire process is equipped with a "recycled water" system to achieve water resource reuse.

[0025] Because the strong magnetic tailings obtained after coarse-grained strong magnetic roughing and scavenging still contain ilmenite that has not been effectively recovered due to intergrowth, fine particle size, or weak magnetic properties, direct disposal results in a low total titanium metal recovery rate (typically only 60%-65%). Although the existing process controls the particle size of the main concentrate through "high-frequency fine screening for titanium beneficiation grinding," there are no recovery or particle size optimization measures for the final discarded "strong magnetic tailings," leading to resource waste.

[0026] The present invention aims to extract tailings from a specific node of the main process and construct an independent, efficient, closed-loop recycling system.

[0027] Example 1: Closed-circuit gravity separation process based on scavenging concentrate return to cleaning This embodiment illustrates the core closed-loop process of the present invention. For example... Figure 2 As shown, the specific steps are as follows: S1. Tailings interception: All the tailings slurry discharged from the tailings outlet of the existing "coarse-grained strong magnetic roughing and scavenging" equipment in the main process is intercepted and used as feed for this system. The TiO2 grade in this slurry is about 3.8% to 5.2%, the particle size is mainly -0.074mm, and the slurry concentration is about 15% to 25%.

[0028] S2. Thickening and Slurry Adjustment (Optional): To optimize separation conditions, the slurry collected in step S1 is transported to a gravity thickener (e.g., a center-driven thickener of model NZS-15). An appropriate amount of polyacrylamide flocculant (5-10 g / t dry ore) is added to concentrate and stabilize the slurry concentration within the range of 40% to 60%. The thickener overflow is returned to the main process circulating water system, and the thickener underflow is used as qualified feed.

[0029] S3. Gravity roughing: The concentrated underflow obtained in step S2 (or the slurry from step S1) is pumped to the gravity roughing equipment. In this embodiment, the gravity roughing equipment uses a set of 5LL-1200 spiral chute, installed at an inclination angle of 12°, with the feed volumetric flow rate controlled at 8~10 m³ / s. 3 / h. After sorting, rough concentrate (TiO2 grade increased to 10%~15%) and rough tailings are obtained.

[0030] S4. Gravity Concentration and Cleaning: The rougher concentrate obtained in step S3 is fed into a gravity concentration and cleaning device. In this embodiment, the gravity concentration and cleaning device uses one or more 6-S type shaking tables connected in series, with the lateral slope of the table surface adjusted to 2.5°, the stroke to 12mm, and the stroke rate to 300 times / minute. After cleaning, a high-grade gravity-concentrated titanium concentrate is obtained, with a TiO2 grade reaching 28%~32%.

[0031] S5. Gravity Separation and Scavenging with Closed-Loop Circulation: The rougher tailings obtained in step S3 are fed into the gravity separation and scavenging equipment. In this embodiment, the gravity separation and scavenging equipment uses one or more 6-S type shaking tables connected in series, and the operating parameters may differ from those of the cleaning shaking table. After scavenging, scavenging concentrate (as middlings, TiO2 grade approximately 6%-10%) and final tailings (TiO2 grade ≤2.0%, which can be discarded) are obtained. The obtained scavenging concentrate is transported back to the feeding trough of the gravity separation and cleaning shaking table in step S4 through a middlings return pipeline and a slurry pump. After mixing with the rougher concentrate from step S3, it enters the cleaning operation together. The flow rate of middlings return accounts for 20%~35% of the total feed of the cleaning operation. This design constitutes an internal closed-loop circulation of "scavenging-cleaning", effectively avoiding the loss of recoverable minerals in the scavenging section, and significantly improving the processing capacity of the cleaning section and the overall metal recovery rate by continuously replenishing the initially enriched middlings for the cleaning operation.

[0032] Example 2: Optimized process including particle size classification control This embodiment, based on Embodiment 1, further controls the particle size of the gravity separation titanium concentrate to improve product quality.

[0033] After obtaining the reselected titanium concentrate in step S4, the following steps are added: S6. Particle Size Classification: The gravity separation titanium concentrate slurry is fed into a high-frequency fine screen (e.g., a Derek 2SG48-60W-5STK type) for wet screening. The screen aperture size of the high-frequency fine screen can be selected according to product requirements, ranging from 0.074 mm to 0.15 mm; in this embodiment, 0.1 mm is preferred. After screening, undersize product (-0.1 mm particle size) and oversize product (+0.1 mm particle size) are obtained.

[0034] S7. Product Processing and Regrinding Closed Loop: The undersize product is produced as the final gravity separation titanium concentrate with qualified particle size. The oversize product is returned to the secondary titanium ball mill in the main process via conveyor equipment (such as belt conveyor) for regrinding to dissociate the ilmenite intergrowths. The regrinded product is selectively returned to the feed end of the gravity separation and cleaning equipment in this system, or it can be returned to the feed end of the main process titanium hydrocyclone, forming a cross-system particle size control closed loop to further optimize resource utilization.

[0035] Example 3: Closed-circuit reselection system for implementing the above process This embodiment provides a modular closed-loop reselection system for implementing the process described in Embodiment 1 or 2, which can be easily integrated into existing beneficiation plants.

[0036] The system mainly includes the following equipment units connected in sequence via pipelines: The interception and concentration unit includes a diversion valve connected to the main process tailings pipeline, and a gravity concentration machine equipped with an automatic dosing device and a concentration sensor.

[0037] The gravity separation unit includes a spiral chute assembly for roughing (gravity roughing equipment), one or more shaking tables A connected in series for cleaning (gravity cleaning equipment), and one or more shaking tables B connected in series for scavenging (gravity scavenging equipment). The feed inlet of the spiral chute assembly is connected to the outlet of the underflow pump of the gravity thickener; its concentrate outlet is connected to the feed end of shaking table A via a chute; and its tailings outlet is connected to the feed end of shaking table B via a chute.

[0038] Closed-loop circulation unit: includes a middlings return pipeline and pumping equipment. The concentrate outlet of shaking table B (scavenging equipment) is connected to the feed distribution box of shaking table A (cleaning equipment) through this pipeline, thereby forcibly returning the scavenged concentrate to the front end of the cleaning operation.

[0039] Particle size control unit (optional): includes a high-frequency fine screening device. The concentrate outlet of shaking table A is connected to the feed inlet of the high-frequency fine screening device; the undersize outlet of the high-frequency fine screening device is the final product outlet, and its oversize outlet is connected to the feed inlet of the two-stage titanium ball mill in the main process via pipeline.

[0040] All the equipment in the system can be integrated into a single steel platform, forming an independent module. During installation, only the tailings feed pipe, concentrate output pipe, oversize return pipe, and circulating water pipe of the main process need to be connected, with minimal impact on the main process production.

[0041] Example 4: Industrial Application Effects To verify the effectiveness of this invention, an industrial trial was conducted at an ilmenite beneficiation plant. The system module described in Example 3 was integrated into the production process and operated continuously and stably for 30 days.

[0042] The main process, "coarse-grained strong magnetic roughing and scavenging" tailings, has an average processing capacity of 520 tons / day (dry ore) and an average TiO2 grade of 4.5%. The produced gravity-separated titanium concentrate has an average TiO2 grade of 29.8% and an average particle size of -0.074mm content of 86.5%. The TiO2 recovery rate in the feed (i.e., the intercepted strong magnetic tailings) reaches 40.2%. This translates to an increase in the plant's total titanium metal recovery rate from 64.5% to 69.8%, an absolute increase of 5.3 percentage points. The system's internal closed-loop circulation is stable, with the middlings return ratio automatically controlled at around 28%, having no negative impact on any indicators of the main process.

[0043] The experimental results show that the present invention, through its original closed-circuit gravity separation process and system of "sweeping and returning finely selected ore", can economically, efficiently and stably recover ilmenite from the strong magnetic tailings discarded in traditional processes, significantly improving the level of comprehensive resource utilization and economic benefits.

[0044] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0045] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A closed-circuit gravity separation process for recovering ilmenite from strongly magnetic tailings, characterized in that, Includes the following steps: Extract tailings discharged after the coarse-grained strong magnetic roughing and scavenging operation in the main process; The tailings are subjected to gravity separation and roughing to obtain roughing concentrate and roughing tailings; The rough concentrate is subjected to gravity separation and further refining to obtain gravity-separated titanium concentrate; The roughing tailings are subjected to gravity separation and scavenging to obtain scavenging concentrate and final tailings. The scavenged concentrate is returned to the feed end of the gravity separation and cleaning operation to form an internal closed loop.

2. The process according to claim 1, characterized in that, The main process is a combined magnetic-flotation separation process for ilmenite, which includes at least the following operations performed in sequence: strong magnetic separation, coarse strong magnetic roughing, coarse strong magnetic roughing scavenging, classification and regrinding, coarse two-stage de-ironization, coarse strong magnetic cleaning, and coarse flotation.

3. The process according to claim 1, characterized in that, Prior to the gravity separation and roughing, the process also includes: concentrating the collected tailings to obtain a slurry with a mass concentration of 40% to 60%.

4. The process according to claim 2, characterized in that, It also includes classifying the gravity-separated titanium concentrate, with the undersize material used as the final product and the oversize material returned to the main process for regrinding.

5. The process according to claim 4, characterized in that, The grading is carried out using a high-frequency fine sieve with a sieve aperture size of 0.074 mm to 0.15 mm.

6. The process according to claim 4, characterized in that, The regrinded product is selectively returned to the re-selection and cleaning operation feed end or the grading operation feed end of the main process, depending on its particle size distribution.

7. The process according to claim 1, characterized in that, The reselection and scanning process includes at least two cascaded scanning operations; and / or, the reselection and selection process includes at least two cascaded selection operations.

8. A closed-circuit gravity separation system for recovering ilmenite from strongly magnetic tailings, characterized in that, For implementing the process according to any one of claims 1 to 7, comprising: The feed inlet of the gravity separation roughing equipment is connected to the tailings outlet of the coarse-grained strong magnetic roughing and scavenging equipment in the main process. The gravity separation and cleaning device has its feed inlet connected to the concentrate outlet of the gravity roughing device; The gravity separation and scavenging equipment has its feed inlet connected to the tailings outlet of the gravity roughing equipment; The concentrate outlet of the gravity separation and scavenging equipment is connected to the feed end of the gravity separation and cleaning equipment via a pipeline.

9. The system according to claim 8, characterized in that, It also includes a gravity concentration unit located before the gravity coarsening unit.

10. The system according to claim 8, characterized in that, Also includes: The high-frequency fine screening equipment has its feed inlet connected to the concentrate outlet of the gravity separation and cleaning equipment, its undersize outlet as the product outlet, and its oversize outlet connected to the feed inlet of the regrinding operation of the main process.

Images