A process configuration method for tailings re-election foam classification return

Abstract

The application discloses a tailing re-election foam grading return process configuration method, relates to the tailing flotation technical field, and adds a grading device to the tailing re-election foam before the tailing re-election foam returns to the original flotation system to perform grading treatment on the re-election foam, and three treatment modes are adopted according to the foam properties: (1) when the re-election foam is seriously slimed, the re-election foam is returned to roughing or cleaning operation after desliming operation; (2) when the fine particle grade is higher than the coarse particle grade, the fine particle foam is returned to the first cleaning stage, and the coarse particle is returned to the grinding operation; (3) when the coarse particle grade is higher than the fine particle grade, the coarse particle is returned to the regrinding device, and the fine particle is returned to the roughing operation. The application realizes accurate return of the re-election foam through grading treatment, shortens the movement path of the valuable metal in the process, reduces the influence of the return product on the original system, effectively improves the metal recovery rate in the tailing, and has the advantages of low equipment investment, simple process transformation, strong adaptability and the like.

Description

Technical Field

[0001] This invention relates to the field of tailings flotation technology, specifically to a process configuration method for tailings re-selection, froth classification, and return, which is particularly suitable for the re-selection and recovery of low-grade valuable metals in copper tailings. Background Technology

[0002] In the beneficiation of non-ferrous metals, flotation tailings still contain a certain amount of valuable metals. How to efficiently recover these valuable metals from the tailings has always been a crucial issue in the beneficiation field. Taking a large underground copper mine in Yunnan Province as an example, this mine is located at a high altitude and employs a fully underground mining model. The ore is characterized by low grade and associated polymetallic deposits such as molybdenum, gold, and silver, with significant fluctuations in mud content and unstable properties. In its existing crushing and grinding + mixed flotation process, the flotation stage, as the core of mineral separation, has extremely high requirements for equipment adaptability, process linkage, and environmental and economic efficiency. The service life of a beneficiation plant is generally 15-20 years, but the initial process flow, reagent system, and equipment configuration are insufficient to meet the constantly changing needs of the ore properties. With the continuous changes in the properties of the ore supplied from the mine, the grade of the flotation tailings fluctuates greatly, and the overall recovery rate shows a decreasing trend.

[0003] In engineering practice, to address the decrease in flotation recovery rate, scavenging operations and extended flotation time are typically added to the existing process. However, due to the application of flotation machines of the same specifications, the enrichment effect of a single flotation machine is limited: when the operating rate is controlled too low, the return to the front-end operation has little impact on improving the overall recovery rate; when the operating rate is too high, it increases the circulating load of the front-end process and may even worsen the original flotation effect. Furthermore, to achieve effective recovery of metals from tailings, a thorough cleaning operation is required, involving repeated flotation from the tail end of the process to the concentrate outlet. This long process path results in poor overall recovery of metals recovered from tailings re-processing.

[0004] Several tailings reprocessing solutions exist in the existing technology. For example, CN110038717A discloses a vanadium-titanium magnetite tailings reprocessing technology, which recovers iron and titanium from tailings through a process of pre-selection + regrinding + magnetic separation. However, this solution belongs to gravity separation and magnetic separation processes and cannot solve the problem of tailings reprocessing for non-magnetic or weakly magnetic minerals. CN120618676A discloses a comprehensive utilization method for the recovery of tailings from refractory ores, which performs strong magnetic recovery followed by regrinding and reprocessing for coarse-grained lean intergrowth iron ore. The applicable scenarios are also mainly magnetic minerals. CN117531609A discloses a method for recovering lean intergrowths from copper tailings, which uses a shallow trough flotation machine and optimizes the return point of tailings reprocessing froth. However, it has problems such as low grade of tailings reprocessing froth, high froth yield, significant impact on the original process after centralized return to the front end, and limited improvement in actual recovery rate. CN119387024A discloses a method for re-selecting titanium concentrate from vanadium-titanium magnetite tailings, which adopts a combined process of staged grinding + magnetic separation + gravity separation + flotation. However, the tailings re-selection system requires a large number of devices, has a complex process, and is not suitable for non-magnetic or weakly magnetic minerals.

[0005] Through long-term research and practice, the inventors discovered that metal loss in tailings exhibits a specific particle size distribution, meaning the main loss occurs within a particular particle size range, typically coarse or fine. Furthermore, due to the instability of the ore properties, this particle size distribution of metal loss can change, along with the mud content. While existing equipment and technology can barely recover some tailings resources, returning them to the original process still results in ineffective recovery, only increasing the process load. Moreover, tailings reprocessing produces low-grade froth with high yields; returning them to the original process would negatively impact the original system's operational efficiency, increase reagent costs, and limit the actual improvement in system recovery rate. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems of low tailings reprocessing recovery rate, long recovery process, large impact on the original system, and high equipment investment in the prior art. It provides a process configuration method for tailings reprocessing foam classification and return, which aims to improve the tailings metal recovery rate, shorten the path of reprocessed foam products in the process, reduce the impact on the original system, and reduce equipment investment.

[0007] To achieve the above objectives, this invention provides a process configuration method for returning tailings re-selection foam classification. A classification device is added before the tailings re-selection foam is returned to the original flotation system to classify the re-selection foam. The foam is then processed according to different conditions after classification, as follows: (1) When the foam becomes severely muddy during re-selection, desliming operation is carried out, and the deslimed foam is returned to the original roughing or cleaning operation; (2) When the fine grade is higher than the coarse grade, the fine-grade foam after classification is returned to the first stage of the cleaning operation, and the coarse-graded product after classification is returned to the grinding operation before flotation in the original system or an additional mill is added for separate grinding. (3) When the grade of coarse particles is higher than that of fine particles, the coarse particles after classification are returned to the regrinding unit before fine selection, and the fine particles after classification are directly returned to the roughing operation.

[0008] As a further improvement of the present invention, in the method (1), "severe mudification" means that the content of -400 mesh particles in the tailings re-selection foam exceeds 30%, and the grade of valuable metals in this particle size is lower than 60% of the average grade of the tailings.

[0009] As a further improvement of the present invention, in method (2), "fine-grained grade is higher than coarse-grained grade" means that, with the grading particle size as the boundary, the valuable metal grade of the fine-grained product is more than 20% higher than that of the coarse-grained product, and the fine-grained metal content accounts for more than 50% of the total metal content.

[0010] As a further improvement of the present invention, in the method (3), "the grade of coarse particles is higher than that of fine particles" means that, with the grading particle size as the boundary, the grade of valuable metals in coarse particles is more than 20% higher than that in fine particles, and the amount of metals in coarse particles accounts for more than 50% of the total amount of metals.

[0011] As a further improvement of the present invention, if the product that needs to be refmilled after classification is returned to the original roughing operation, it is returned to the ball mill before the roughing operation in the original flotation system.

[0012] As a further improvement of the present invention, when the grading process needs to be returned to the cleaning operation, if the original flotation system has a rough concentrate regrinding operation, the regrinding operation before returning to the cleaning operation is combined; if the original flotation system does not have a rough concentrate regrinding operation, a separate regrinding operation is established.

[0013] As a further improvement of the present invention, the grading device is a hydrocyclone, a high-frequency fine screen, or a spiral chute.

[0014] As a further improvement of the present invention, the regrinding device is a vertical mill, a ball mill, a horizontal mill, or an abrasive mill.

[0015] As a further improvement of the present invention, the tailings are copper tailings.

[0016] The beneficial effects of this invention are as follows: First, the tailings re-selection froth is graded using a classification device to achieve coarse and fine particle classification. The classification operation solves the problem of insufficient overall grade in the mixed return process. In cases with a high degree of mudding, the fine particles contain a lot of mud, and returning them to the original process will worsen the separation effect and increase reagent consumption. By classifying, the mud content in the system can be reduced with a low loss of recovery rate, thereby enhancing the separation effect of the original process.

[0017] Secondly, for re-selected froth composed mainly of fine particles and supplemented by lean intergrowths, the grade of fine particles can be further improved through classification operations, so as to achieve the purpose of returning to the concentrate outlet operation and increase the probability of froth being discharged from the concentrate outlet; for coarse intergrowths, regrinding can be carried out to increase the degree of liberation of coarse intergrowths and reduce the total amount of grinding required.

[0018] Third, for coarse particles with high grade and high metal content, they can be directly or after regrinding into roughing or even cleaning operations after classification, which shortens the flow distance of the re-selected foam in the process and increases the recovery probability. For low-grade fine particles, they can be directly returned to roughing or front-end scavenging operations according to grade, which reduces the impact on the system and increases the system recovery rate.

[0019] Fourth, this invention only requires the addition of tailings foam classification equipment and regrinding equipment, without adding any other equipment. The equipment investment is low, the process modification is simple and easy to implement, the modification cost is low, and it is suitable for large-scale industrial applications.

[0020] Fifth, this invention can effectively adapt to the fluctuations in tailings properties caused by changes in ore properties, and flexibly select the processing path according to the actual properties of the tailings re-selection foam, thus having wide applicability and good operational flexibility. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the three foam treatment scenarios selected in this invention; Figure 2 This is a device configuration diagram for Embodiment 2 of the present invention; Figure 3 This is a flow chart of the flotation tailings reprocessing process in Embodiment 2 of the present invention, wherein the dashed box represents the improved process of the present invention, and the rest represents the original process flow. Figure 4 For pharmaceutical systems; Figure 5 The production targets for Series I of a certain copper mine in April and May; Figure 6 The particle size analysis of flotation tailings from a copper mine's Series I flotation process in April and May; Figure 7 The reprocessing indicators for the I-series tailings of a certain copper mine; Figure 8The results of froth particle size analysis of the I-series tailings of a copper mine; Figure 9 This document presents the performance indicators before and after the modification of the I-series process at a copper mine. Detailed Implementation

[0022] 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.

[0023] Example 1 This invention addresses the problem of low metal recovery rate in tailings from three main aspects: First, improve the enrichment ratio and grade of tailings reprocessing froth. By adding a tailings reprocessing system and increasing the residence time of the slurry, the grade and enrichment effect of the froth product can be improved, so that the froth grade meets the requirements for return to roughing or even cleaning operations. At the same time, the yield of tailings reprocessing operations can be reduced, alleviating the cyclical load of upstream processes (including grinding, classification, and flotation) and ensuring the equipment efficiency of the original processes.

[0024] Second, it shortens the movement path of tailings re-selection froth products in the process. The application of flotation equipment technology can target and enhance the recovery of each particle size in the tailings based on the loss situation, solving the problem that conventional flotation equipment technology cannot focus on the recovery of specific particle sizes. The re-selection froth can be returned to the roughing or even cleaning operation according to the classification results, which greatly shortens the path length of the re-selection froth to the concentrate outlet.

[0025] Third, the tailings are graded and sorted based on the differences in the particle size composition of the foam. Products with different properties are selectively returned to different upstream operations, reducing the impact on upstream processes while maximizing the recovery effect of each particle size.

[0026] See Figure 1 Where A represents the treatment path when mudification is severe, B represents the treatment path when the fine-grained grade is higher than the coarse-grained grade, and C represents the treatment path when the coarse-grained grade is higher than the fine-grained grade. This invention provides a process configuration method for returning tailings re-selection froth classification, which adds a classification device to classify the re-selection froth before returning it to the original flotation system, and processes the classified froth according to the following methods depending on the different situations: (1) When the foam becomes severely muddy during re-selection, desliming operation is carried out, and the deslimed foam is returned to the original roughing or cleaning operation; (2) When the fine grade is higher than the coarse grade, the fine-grade foam after classification is returned to the first stage of the cleaning operation, and the coarse-graded product after classification is returned to the grinding operation before flotation in the original system or an additional mill is added for separate grinding. (3) When the grade of coarse particles is higher than that of fine particles, the coarse particles after classification are returned to the regrinding unit before fine selection, and the fine particles after classification are directly returned to the roughing operation.

[0027] Furthermore, in the method (1), "severe mudification" means that the content of -400 mesh particles in the tailings re-selection foam exceeds 30%, and the grade of valuable metals in this particle size is lower than 60% of the average grade of the tailings.

[0028] Furthermore, in the method (2), "the grade of fine particles is higher than that of coarse particles" means that, based on the particle size, the grade of valuable metals in fine particles is more than 20% higher than that in coarse particles, and the amount of metals in fine particles accounts for more than 50% of the total metal content.

[0029] Furthermore, in the method (3), "the grade of coarse particles is higher than that of fine particles" means that, based on the particle size, the grade of valuable metals in coarse particles is more than 20% higher than that in fine particles, and the amount of metals in coarse particles accounts for more than 50% of the total amount of metals.

[0030] Furthermore, if the product needs to be refmilled after classification, it should be returned to the ball mill in the original flotation system before the roughing operation if it is to be returned to the original roughing operation.

[0031] Furthermore, when the grading process needs to return to the cleaning operation, if the original flotation system has a rough concentrate regrinding operation, the regrinding operation before returning to the cleaning operation will be combined; if the original flotation system does not have a rough concentrate regrinding operation, a separate regrinding operation will be established.

[0032] Furthermore, the grading device is a hydrocyclone, a high-frequency fine screen, or a spiral chute.

[0033] Furthermore, the regrinding device is a vertical mill, ball mill, horizontal mill, or sand mill.

[0034] Furthermore, the tailings are copper tailings.

[0035] Example 2 A large copper mine in Yunnan Province has a Series I copper flotation system with a copper tailings processing capacity of 21,000 t / d. The system employs a one-roughing, three-scavenging, and two-cleaning operation. The roughing process uses five WEMCO-330m³ flotation machines, and scavenging operations I through III each use one WEMCO-330m³ flotation machine. The equipment configuration is as follows: Figure 2 As shown. The feed particle size of -200 mesh accounts for 68%–73%, and the fineness of the regrinded rough concentrate after grinding is over 80% -300 mesh. The reagent regime is as follows. Figure 4 As shown. Average production indicators for April and May are as follows: Figure 5 As shown.

[0036] With an input grade of approximately 0.309%, the concentrate grade was approximately 17.36%, the tailings grade was approximately 0.063%, and the recovery rate was 79.90%. This is lower and fluctuates significantly compared to the average recovery rate of approximately 81% over the past three years. The flotation tailings particle size analysis data are as follows: Figure 6 As shown.

[0037] Analysis shows that the -400 mesh particle size had the highest grade and metal content, reaching 0.094% and 54.49% respectively, followed by the +100 mesh particle size, at 0.079% and 21.11% respectively. Other particle sizes had grades below the average and low metal content. Metal loss in tailings was primarily due to fine particles, with coarse particles contributing a smaller portion. Fine particles showed higher degree of individual particle liberation, while coarse particles were mainly composed of intergrowths. (Refer to...) Figure 1 The implementation plan adopts the scheme (2), namely, the situation where "the fine particle grade is higher than the coarse particle grade", and carries out on-site modification.

[0038] A new HIF-800m³ full-size flotation machine will be added after the Phase III scavenging operation to further process the tailings (the existing 330m³ flotation machine for Phase III operation will remain unchanged, with the new HIF-800m³ flotation machine added at its tailings outlet). Given the significant losses of both coarse and fine metals in the tailings, the HIF-800m³ full-size flotation machine will be used. This will enhance the recovery of coarse intergrowths through relatively shallow tank technology, and enhance the recovery of fine particles through high impeller Reynolds number and the application of microbubbles, ultimately achieving the goal of targeted enhancement of both coarse and fine particle recovery.

[0039] The process flow configuration method in scheme (2) is used for the re-selection of flotation tailings. The process flow is as follows: Figure 3 As shown, an additional flotation machine is added after the third scavenging operation to further process the tailings. The fine-grained tailings froth, after classification, is directly fed into the first cleaning operation, while the coarse-grained intergrowth is fed into the roughing operation after grinding. The classification operation uses a φ250×4 high-efficiency hydrocyclone group to classify the reprocessed froth, achieving classification between +300 mesh and -300 mesh, with a classification efficiency of 85%. The tailings reprocessing parameters are as follows: Figure 7 As shown. In this invention, the enrichment ratio = tailings re-selection froth grade ÷ tailings re-selection feed grade. The tailings re-selection froth particle size analysis results are as follows. Figure 8 As shown.

[0040] Analysis shows that through the implementation of this invention, the tailings re-selection froth grade reached 2.20%, and the enrichment ratio reached 31.9, which well met the requirements for return to roughing or even cleaning. Further analysis of the particle size distribution in the froth product shows that the application of the HIF-800 flotation machine effectively improved the recovery of both coarse and fine particles. The -400 mesh grade and metal content had the highest proportions, at 2.39% and 68.02% respectively, followed by the +100 mesh grade and metal content, at 2.02% and 14.62% respectively. After the implementation of the solution, the average production indicators in June were as follows: Figure 9 As shown.

[0041] Analysis shows that by adding tailings reprocessing, the final concentrate grade increased by 1.036 percentage points and the recovery rate increased by 1.70 percentage points, with the raw ore grade remaining basically the same, demonstrating the significant effect of process modification.

[0042] Example 3 A copper ore beneficiation plant processed ores with a high mud content. The -400 mesh content in the flotation tailings exceeded 45%, and the fine-grained mudification was severe. Re-concentration froth screening of the tailings showed that the -400 mesh particle size accounted for 48% of the yield. This particle size contained over 85% gangue minerals, with a valuable metal grade of only 0.03%, lower than the average tailings grade of 60%, indicating severe mudification.

[0043] By employing the technical solution of this invention, a classification device is added before the tailings re-selection foam is returned for classification treatment, first performing a desliming operation. The deslimed foam is returned to the original roughing operation, while the removed ore slime is directly fed into the tailings.

[0044] By performing desliming operations, the mud content in the system was effectively reduced, avoiding the problems of fine mud deteriorating the separation effect and increasing reagent consumption after being returned to the original process. After the modification, the separation environment of the original flotation system was significantly improved, the concentrate grade increased by about 0.8 percentage points, and the collector dosage was reduced by about 10%.

[0045] Example 4 Screening data from flotation tailings at a copper ore beneficiation plant showed that the +200 mesh size contained over 60% metal, with a Cu grade of 0.12%, while the -200 mesh size had a Cu grade of only 0.035%. The coarse-grained grade was approximately 70% higher (relatively) than the fine-grained grade, indicating a situation where the coarse-grained grade was higher than the fine-grained grade. The coarse-grained portion was predominantly composed of depleted intergrowths with insufficient liberation.

[0046] By adopting the technical solution of this invention, a classification device is added before the tailings are returned to the foam for classification. After classification, the coarse particles (+200 mesh) are returned to the regrinding device before the finer particles are selected, which increases the degree of liberation and ensures the concentrate grade of subsequent operations; the fine particles (-200 mesh) are directly returned to the roughing operation for further recovery.

[0047] Through graded regrinding, the coarse intergrowth was fully liberated, significantly improving the re-concentration recovery rate; low-grade fine particles were directly returned to the roughing stage, avoiding any impact on the concentrate grade in the finishing process. After the upgrade, the overall recovery rate of tailings re-concentration increased by approximately 2.5 percentage points.

[0048] 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 process configuration method for tailings re-selection, foam classification, and return, characterized in that, Before the tailings re-selection froth is returned to the original flotation system, a classification device is added to classify the re-selection froth, and the different situations after froth classification are handled in the following ways: (1) When the foam becomes severely muddy during re-selection, desliming operation is carried out, and the deslimed foam is returned to the original roughing or cleaning operation; (2) When the fine grade is higher than the coarse grade, the fine-grade foam after classification is returned to the first stage of the cleaning operation, and the coarse-graded product after classification is returned to the grinding operation before flotation in the original system or an additional mill is added for separate grinding. (3) When the grade of coarse particles is higher than that of fine particles, the coarse particles after classification are returned to the regrinding unit before fine selection, and the fine particles after classification are directly returned to the roughing operation.

2. The process configuration method for tailings reprocessing and foam classification return according to claim 1, characterized in that: In the method (1), "severe mudification" means that the content of -400 mesh particles in the tailings re-selection foam exceeds 30%, and the grade of valuable metals in this particle size is lower than 60% of the average grade of the tailings.

3. The process configuration method for tailings reprocessing and foam classification return according to claim 1, characterized in that: In method (2), "fine-grained grade is higher than coarse-grained grade" means that, based on the grading particle size, the valuable metal grade of fine-grained products is more than 20% higher than that of coarse-grained products, and the amount of fine-grained metal accounts for more than 50% of the total metal amount.

4. The process configuration method for tailings re-selection and foam classification return according to claim 1, characterized in that: In method (3), "the grade of coarse particles is higher than that of fine particles" means that, based on the particle size, the grade of valuable metals in coarse particles is more than 20% higher than that in fine particles, and the amount of metals in coarse particles accounts for more than 50% of the total metal content.

5. The process configuration method for tailings re-selection and foam classification return according to claim 1, characterized in that: Products that require further grinding after classification should be returned to the original roughing operation, specifically to the ball mill before the roughing operation in the original flotation system.

6. The process configuration method for tailings re-selection and foam classification return according to claim 1, characterized in that: If the grading process requires returning to the cleaning operation, and if the original flotation system has a rough concentrate regrinding operation, then the regrinding operation before returning to the cleaning operation should be combined. If the original flotation system does not have a regrinding operation for rough concentrate, then a separate regrinding operation should be established.

7. The process configuration method for tailings re-selection and foam classification return according to claim 1, characterized in that: The grading device is a hydrocyclone, a high-frequency fine screen, or a spiral chute.

8. The process configuration method for tailings reprocessing and foam classification return according to claim 1, characterized in that: The regrinding device is a vertical mill, ball mill, horizontal mill, or sand mill.

9. The process configuration method for tailings re-selection and foam classification return according to claim 1, characterized in that: The tailings are copper tailings.

Images