A method of recovering lean intergrowths from copper tailings

Abstract

This invention relates to a method for recovering lean intergrowths from copper tailings, belonging to the field of copper tailings recovery technology. This invention utilizes a shallow-tank flotation machine for copper tailings flotation in existing copper flotation processes, selecting coarse particles in the copper tailings as the target for copper recovery. By combining optimized flotation reagents and a streamlined tailings concentrate process design, it overcomes the problems of coarse copper tailings particles being difficult to adhere to bubbles, poor stability of adhered minerals leading to easy detachment, low re-flotation yield, thin and unstable foam, and long flotation time requirements. This method achieves copper recovery from +0.074mm coarse-grained tailings, improving copper resource utilization and providing a new, industrially applicable method for the recovery and utilization of lean intergrowths in copper tailings.

Description

Technical Field

[0001] This invention belongs to the field of copper tailings recovery technology, specifically, it relates to a method for recovering lean intergrowths in copper tailings. Background Technology

[0002] my country's copper reserves account for only about 4% of the world's total. Improving resource utilization is an urgent problem to be solved. Factors such as ore depletion, declining ore grade, gangue mixing, and low liberation degree of coarse particles have led to a large amount of copper tailings resources in my country.

[0003] Currently, there are many methods for recovering copper tailings, such as: using hydrocyclones and fluidized bed separators to recover copper from tailings (e.g., patent CN218742469U), using ultrasonic treatment to recover copper from tailings (e.g., patent CN107185725A), using air-source heat pump leaching to recover copper from tailings (e.g., patent CN105274331A), and using a system consisting of spiral sluices, centrifugal concentrators, paste thickeners, shaking tables, ball mills, and settling tanks to recover copper from tailings (e.g., patent CN206965908U). However, current copper tailings recovery methods are not only complex in system structure and process, and energy-intensive, but are also mostly in the laboratory experimental stage, making industrial application difficult or impossible. Even under refined laboratory operations, the processing efficiency of copper tailings is very low, making it difficult to recover copper from tailings. Summary of the Invention

[0004] To address the problems in the background technology, the inventors conducted particle size analysis on copper tailings and found that copper minerals in the ore sample were mainly enriched in the +0.074mm and -0.025mm particle size ranges.

[0005] Table 1 Results of particle size analysis of mineral samples

[0006] Particle size, mm Yield, % Cu grade, % Cu distribution rate, % +0.125 25.29 0.10 37.14 -0.125+0.074 13.87 0.070 14.26 -0.074+0.045 15.99 0.037 8.69 -0.045+0.038 2.69 0.033 1.30 -0.038+0.025 5.06 0.028 2.08 -0.025 37.10 0.067 36.53 Mineral feed 100.00 0.068 100.00

[0007] Mineralogical identification of copper tailings (attached) Figure 1The main mineral types and their distribution characteristics in the tailings were analyzed. The results showed that the main metallic minerals in the tailings were chalcopyrite and pyrite. However, the chalcopyrite was extremely fine-grained, with a degree of liberation of less than 5%, and mainly formed inclusions or poor intergrowths closely associated with gangue minerals. The tailings distribution characteristics analysis showed that chalcopyrite mainly formed inclusions or poor intergrowths closely associated with gangue minerals, with a degree of liberation of less than 5%, and most of its grain size was less than 0.045 mm, with the majority distributed between 0.005 and 0.035 mm. The degree of liberation of pyrite was approximately 75%, with a maximum grain size of 0.1 mm, and most distributed between 0.01 and 0.06 mm. Considering the tailings situation, this invention selected the +0.074 mm grain size as the primary recovery target.

[0008] Analysis of the particle size and embedding characteristics of +0.074mm coarse minerals reveals the following problems in the recovery of +0.074mm tailings: (1) low degree of liberation, making it difficult to adhere to bubbles; (2) poor stability of adhered minerals, making them easy to fall off; (3) low re-selection yield, difficulty in forming a thick foam layer, and poor foam stability; (4) long flotation time requirement.

[0009] To overcome the above four problems and achieve copper recovery from +0.074mm coarse-grained tailings, this invention has developed a method for recovering lean intergrowths from copper tailings through extensive research. By using flotation reagents and improving the copper ore flotation process, copper recovery from copper tailings is achieved, significantly increasing the copper recovery rate.

[0010] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0011] The method for recovering lean intergrowths from copper tailings includes the following steps:

[0012] (1) Semi-auto-grind and screen the copper ore;

[0013] (2) Perform a single cyclone classification to obtain a single-classified fine-grained slurry and a single-classified coarse-grained slurry;

[0014] (3) The primary classification coarse slurry is ball-milled and returned to the primary cyclone classification; the primary classification fine slurry is mixed and roughened.

[0015] (4) The mixed roughing concentrate is subjected to secondary cyclone classification to obtain secondary fine-grained slurry and secondary coarse-grained slurry; the tailings of the mixed roughing are scavenged.

[0016] (5) The fine slurry from the secondary classification is further refined, and the coarse slurry from the secondary classification is returned to the vertical mill.

[0017] (6) The scavenging tailings from step (4) are added to flotation reagents and floated using a flotation machine; the scavenging concentrate is returned to the mixing roughing process in step (3);

[0018] (7) The fine tailings from step (5) are returned to the mixed roughing process in step (3);

[0019] The flotation reagents in step (6) are Z200, butyl xanthate, CaO and pine oil.

[0020] Furthermore, after flotation of the tailings in step (6) using a flotation machine, a foam product is obtained, and the obtained foam product is returned to the ball mill in step (3) or the vertical mill in step (5).

[0021] Furthermore, in step (2), the particle size of the fine-grained slurry in the primary classification is 68%-73% for a particle size of -200 mesh.

[0022] Furthermore, in step (6), the flotation reagents are: Z200 dosage of 7-18 g / t feed, butyl xanthate dosage of 5-20 g / t feed, CaO dosage of 200-750 g / t feed, and pine oil dosage of 3-20 g / t feed.

[0023] Furthermore, the flotation machine used in step (6) is a shallow trough flotation machine; the shallow trough flotation machine includes a tank body, a stirring shaft, a stator ring fixed concentrically with the stirring shaft, a circulation cylinder, and a bottom plate with through holes; a support rod is provided between the bottom plate and the bottom of the tank body to form a circulation channel between the bottom plate and the bottom of the tank; the circulation cylinder is set between the bottom plate and the stator ring; the stator ring, the circulation cylinder, and the bottom plate are fixed concentrically; the stator ring is formed by the stator being fixed circumferentially around the stirring shaft, and the stator ring is set in the middle of the tank body; a foam collection tank is provided inside the tank body, the foam collection tank is an annular tank, and a foam discharge pipe is connected to the tank body to pass through the tank body and discharge the foam product outside the flotation machine.

[0024] Furthermore, an intermediate tank is set in front of the shallow trough flotation machine. The reagents required for flotation are added into the intermediate tank through a pipeline and fully mixed with the slurry before being added to the shallow trough flotation machine.

[0025] The beneficial effects of this invention are:

[0026] (1) This invention performs graded regrinding and enhanced recovery of copper flotation tailings. By selecting flotation agents, the coarse-grained copper-poor intergrowths in the tailings are recovered. The recovered copper-poor intergrowths are then regrinded and floated, which solves the problems of poor liberation of coarse-grained tailings, difficulty in adhering to bubbles, poor stability, and easy detachment. This invention achieves effective flotation recovery of copper-poor intergrowths in copper flotation tailings and improves the copper recovery rate.

[0027] (2) The flotation reagent used in this invention enables coarse-grained depleted intergrowths to be adhered to by bubbles and effectively recovered, increasing the thickness and stability of the foam layer.

[0028] (3) Shallow trough flotation machine is used for tailings recovery. It requires fewer equipment units, occupies less space, and is simple to operate and maintain. In addition, the shallow trough flotation machine, combined with the optimization of the flotation machine, shortens the flotation time and can obtain a foam layer with a thickness of 180-350mm.

[0029] (4) The present invention can adopt a flexible process switching to effectively recover coarse-grained minerals that are easily lost in tailings.

[0030] (5) The use of the shallow trough flotation machine, the improvement of flotation reagents, and the improvement of the combined process of the present invention enable the effective recovery of coarse-grained minerals that are easily lost in the tailings, and the copper recovery rate is effectively improved.

[0031] (6) This invention can be directly industrialized after being improved on-site in existing copper ore flotation equipment. It does not require changing the original copper flotation process, effectively improving the copper yield and the utilization rate of copper resources. It provides a new method for the recovery and utilization of lean intergrowths in copper tailings that can be industrially applied and recycled.

[0032] (7) Shallow trough flotation machines can provide sufficient flotation time and a shorter transport distance for coarse, poor, intergrowth mineral particles that are difficult to recover, and increase the stability of the froth layer. Attached Figure Description

[0033] Figure 1 This is a mineralogical identification diagram of copper tailings.

[0034] Figure 2 This is a simplified process flow diagram of the ball milling stage before roughing of foam products according to the present invention;

[0035] Figure 3 This is a simplified process flow diagram of the process of returning the foam product to the vertical mill stage before refining according to the present invention.

[0036] Figure 4 This is a schematic diagram of the shallow-tank flotation machine of the present invention;

[0037] Figure 5 This is a diagram of the internal material circulation path of the shallow trough flotation machine of the present invention;

[0038] Figure 6 This is a schematic diagram of the flow path of foam into the foam collection tank according to the present invention;

[0039] Remark: Figure 1 In the diagram, a shows an intergrowth of pyrite and feldspar; b shows an intergrowth of copper ore and quartz; c shows a complex intergrowth of chalcopyrite, feldspar, and quartz; and d shows a complex intergrowth of chalcopyrite and quartz.

[0040] In the figure, 1-tank body, 2-stirring shaft, 3-stator ring, 4-circulation cylinder, 5-bottom plate, 6-through hole, 7-support rod, 8-foam collection tank, 9-foam outlet pipe, 10-stirring shaft drive motor, 11-stirring shaft reducer, 12-short-circuit circulation hole, 13-inward push bubble cone. Detailed Implementation

[0041] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are all within the scope of protection of this invention.

[0042] Example 1

[0043] Selection of flotation reagents for copper tailings

[0044] Particle size analysis and microscopic identification results show that the copper minerals in the tailings samples of the Pulang copper mine are mainly coarse-grained intergrowths and some chalcopyrite with poor floatability. Therefore, selecting a suitable collector is particularly important for the flotation of copper tailings.

[0045] The process used is as follows:

[0046] (1) Semi-auto-grind and screen the copper ore;

[0047] (2) Perform a single cyclone classification to obtain a single-classified fine slurry and a single-classified coarse slurry with a particle size of -200 mesh of 68%-73%.

[0048] (3) The primary classification coarse slurry is ball-milled and returned to the primary cyclone classification; the primary classification fine slurry is mixed and roughened.

[0049] (4) The mixed roughing concentrate is subjected to secondary cyclone classification to obtain secondary fine-grained slurry and secondary coarse-grained slurry; the tailings of the mixed roughing are scavenged.

[0050] (5) The fine slurry from the secondary classification is further refined, and the coarse slurry from the secondary classification is returned to the vertical mill.

[0051] (6) The scavenging tailings from step (4) are added to flotation reagents and floated using a shallow trough flotation machine. The scavenging concentrate is returned to the mixed roughing process in step (3).

[0052] (7) The fine tailings from step (5) are returned to the mixed roughing process in step (3);

[0053] (8) Step (6) The flotation foam product is returned to the vertical mill in step (5).

[0054] In this embodiment, other reagent systems still use the reagent system before adding tailings flotation (the process without steps (6) and (8), and the scavenged tailings in step (4) are the final copper tailings). Only the reagents for copper tailings flotation in step (6) are examined, and the results are as follows:

[0055] CaO was selected as the modifier and pine oil was used as the foaming agent. Experiments were conducted using pentyroxanthate, butyl xanthate, Z-200, Z-200 plus butyl xanthate, Z-200 and pentyroxanthate as collectors, and the results are shown in Table 2.

[0056] Table 2. Results of the test on the types of crude collectors.

[0057]

[0058]

[0059] When using combined collectors, the copper recovery rate in tailings reprocessing is relatively high. Among them, the combination of Z-200 and butyl xanthate shows better flotation performance, with a copper grade of 0.58% in the rough concentrate and a copper recovery rate of approximately 21.5%. Z-200 and butyl xanthate are selected as roughing collectors.

[0060] For the selection of frothers, under the condition of fixed CaO dosage, collector Z-200 dosage, and butyl xanthate dosage, MIBC, BK204, and pine oil were used as frothers to investigate the effects of different frothers on copper flotation. The experimental results are shown in Figure 3. The experimental results show that when using No. 2 oil (pine oil) as the frother, the copper recovery rate is the highest, followed by BK204, and MIBC is the worst. Therefore, No. 2 oil is selected as the frother.

[0061] Table 3. Test Results of Foaming Agent Types

[0062]

[0063] Under the condition of fixed dosages of collector Z-200, butyl xanthate, and frother pine oil, experiments were conducted on the types of roughing modifiers. The results are shown in the table. The results show that CaO was used as the modifier, resulting in the highest copper recovery rate, approximately 21.4%. Adding a small amount of sodium sulfide can improve the flotation foam phenomenon, but it significantly reduces the copper grade in the rough concentrate. Adding a small amount of water glass slightly increases the copper grade in the rough concentrate, but it significantly reduces the copper recovery rate. Considering all factors, CaO was selected as the roughing modifier.

[0064] Table 4. Test Results of Modifier Types

[0065]

[0066] By analyzing the particle size of the froth product from copper tailings flotation and collecting and analyzing data such as the overflow rate of the froth product, it was found that the flotation froth layer can recover more than 82.97% of the +0.074mm tailings in copper tailings, which is of great significance for copper tailings recovery. The copper tailings reagent system of this invention not only achieves low-dissociation +0.074mm tailings viscosity on the froth, but also ensures that the adhered tailings are not easily detached, thus realizing the recovery of +0.074mm tailings.

[0067] Example 2

[0068] The Pulang copper mine, with a raw ore grade of 0.35%, was subjected to flotation using the following steps:

[0069] (1) Semi-auto-grind and screen the copper ore.

[0070] (2) Perform a single cyclone classification to obtain a single-stage fine slurry with a particle size of -200 mesh and a single-stage coarse slurry with a particle size of 68%-73%.

[0071] (3) The coarse slurry from the primary classification is ball-milled and returned to the primary cyclone classification; the fine slurry from the primary classification is mixed and roughened.

[0072] (4) The mixed roughing concentrate is subjected to secondary cyclone classification to obtain secondary fine-grained slurry and secondary coarse-grained slurry; the tailings of the mixed roughing are scavenged.

[0073] (5) The fine slurry from the secondary classification is finely selected, and the coarse slurry from the secondary classification is returned to the vertical mill.

[0074] (6) The scavenging tailings from step (4) are added to flotation reagents and floated using a shallow trough flotation machine. The scavenging concentrate is returned to the mixed roughing process in step (3).

[0075] (7) The fine tailings from step (5) are returned to the mixed roughing process in step (3).

[0076] (8) Step (6) The flotation foam product is returned to the vertical mill in step (5).

[0077] The flotation reagents in step (6) are Z2007 g / t feed, butyl xanthate 5 g / t feed, CaO 200 g / t feed and pine oil 4 g / t feed.

[0078] The copper concentrate grade was 20.16%, the copper recovery rate was 82.68%, and the copper content in the tailings was 0.055%. Compared with the existing copper flotation process, under the same reagent system and operating conditions, the system recovery rate is increased by more than 3 percentage points when the raw ore grade is high (≥0.30%) (see Table 5).

[0079] Table 5 compares the steps before and after adding steps (6) and (8).

[0080]

[0081] Note: Steps (6) and (8) are additional steps.

[0082] Example 3

[0083] A copper mine has a raw ore grade of 0.25%. The following steps are used for flotation:

[0084] (1) Semi-auto-grind and screen the copper ore;

[0085] (2) Perform a single cyclone classification to obtain a single-classified fine slurry and a single-classified coarse slurry with a particle size of -200 mesh of 68%-73%.

[0086] (3) The primary classification coarse slurry is ball-milled and returned to the primary cyclone classification; the primary classification fine slurry is mixed and roughened.

[0087] (4) The mixed roughing concentrate is subjected to secondary cyclone classification to obtain secondary fine-grained slurry and secondary coarse-grained slurry; the tailings of the mixed roughing are scavenged.

[0088] (5) The fine slurry from the secondary classification is further refined, and the coarse slurry from the secondary classification is returned to the vertical mill.

[0089] (6) The scavenging tailings from step (4) are added to flotation reagents and floated using a shallow trough flotation machine. The scavenging concentrate is returned to the mixed roughing process in step (3).

[0090] (7) The fine tailings from step (5) are returned to the mixed roughing process in step (3);

[0091] (8) Step (6) The flotation foam product is returned to the vertical mill in step (5).

[0092] The flotation reagents in step (6) are Z200 18g / t feed, butyl xanthate 20g / t feed, CaO 700g / t feed and pine oil 18g / t feed.

[0093] The copper concentrate grade was 18.39%, the copper recovery rate was 79.42%, and the copper content in the tailings was 0.053%. Compared with the existing copper flotation process, the copper recovery rate increased by 0.44 percentage points while keeping the reagent system and operating conditions unchanged.

[0094] Table 6 compares the steps before and after adding steps (6) and (8).

[0095]

[0096]

[0097] Note: Steps (6) and (8) are additional steps.

[0098] Example 4

[0099] This embodiment mainly describes the structure of the shallow trough flotation machine of the present invention. The shallow trough flotation machine used in the present invention adopts a central impeller structure, including a trough body 1, a stirring shaft 2, a stator ring 3 concentrically fixed with the stirring shaft 2, a circulation cylinder 4, and a bottom plate 5 with through holes 6. A support rod 7 is provided between the bottom plate 5 and the bottom of the trough body 1, so that a material circulation channel is formed between the bottom plate and the bottom of the trough body. The circulation cylinder 4 is located between the bottom plate 5 and the stator ring 3, and the bottom is designed as an enlarged conical structure, and the bottom of the conical structure is provided with a short-circuit circulation hole 12. The stator ring 3, the circulation cylinder 4, and the bottom plate 5 are concentrically fixed. The stator ring 3 is formed by the stator being fixed circumferentially around the stirring shaft 2. The stator ring 3 is located in the middle of the trough body, forming a central impeller structure. The trough body 1 is provided with a built-in foam collecting trough 8. The foam collecting trough 8 is an annular trough, concentrically arranged with the stirring shaft 2. A foam discharge pipe 9 passing through the trough body is connected to the foam collecting trough 8. The foam collecting trough 8 is inclined downward toward the foam discharge pipe 9. To address the issues of low froth yield and poor froth stability in tailings flotation, the upper part of the tank 1 adopts a constricted design. Simultaneously, a cylindrical bubble-pushing cone 13, wider at the top and narrower at the bottom, is installed around the inner ring of the froth collection tank 8 and around the outer periphery of the stirring shaft 2. The built-in froth collection tank 8, in conjunction with the bubble-pushing cone 13 and the constricted design at the upper part of the tank 1, effectively reduces the froth area, increases froth stability, and simultaneously promotes the flow of froth towards the froth collection tank 8 (as shown in the attached diagram). Figure 6 When the foam product of the present invention is stably moving in and out, the thickness of the foam layer can reach 180-350mm.

[0100] The circulating cylinder 4 replaces the drive air distributor, featuring larger and fewer air outlets. Its outlet position is closer to the upper part of the stator ring 3, ensuring that the injected air is concentrated primarily in the upper area of ​​the stator ring 3, preventing it from spreading throughout the entire area. This reduces the impact of air ingress on slurry circulation capacity, and the larger air outlets are less prone to clogging by coarse ore particles. The lower part of the circulating cylinder 4 employs a conical structure, which guides the flow of slurry passing through this area while reducing wear and impact from the circulating slurry on the circulating cylinder 4.

[0101] To prevent material deposition at the bottom of the flotation machine, sufficient flow velocity is maintained in the circulation channels of the bottom plate 5 and the tank to prevent mineral particle deposition. Based on the typical settling velocity of mineral particles (0.084 m / s for 1 mm particles at 2.65 t / m³ water; 0.167 m / s for 2.3 mm particles at 2.65 t / m³ water; and 1.0-1.6 m / s for pressure pipeline conveying at 2.65 t / m³ with a 30% concentration), a short-circuit circulation hole 12 is designed in the lower conical section of the circulation cylinder 4, in addition to the through hole 6 on the bottom plate 5. The short-circuit circulation hole 12 locally adjusts the slurry circulation path in the middle area of ​​the flotation machine, enhancing the disturbance in this area and reducing the risk of particle deposition. For conditions where deposition has already occurred or restarting after a shutdown under load, the multiple slurry circulation channels formed by the through hole 6 on the bottom plate 5 and the short-circuit circulation hole 12 can ensure the flotation machine's ability to automatically restore the suspended slurry. The flow pattern of the centrally mounted impeller flotation machine was revealed. It differs significantly from the bottom-mounted impeller type, with a larger lower circulation range and a higher flow velocity inside the guide tube 4, forming a closed-loop circulation system and shortening the transport height of coarse particles.

[0102] Shallow trough flotation machines ensure that mineral bubbles float and are recovered along a shorter path during the flotation process, reducing the shedding of adhered mineral particles during the flotation process.

[0103] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for recovering lean intergrowths from copper tailings, characterized in that, Includes the following steps: (1) Semi-auto-grind and screen the copper ore; (2) Perform a single cyclone classification to obtain a single-classified fine-grained slurry and a single-classified coarse-grained slurry; (3) The coarse slurry from the primary classification is ball-milled and returned to the primary cyclone classification; the fine slurry from the primary classification is mixed and roughened. (4) The mixed roughing concentrate is subjected to secondary cyclone classification to obtain secondary fine-grained slurry and secondary coarse-grained slurry; the tailings of the mixed roughing are scavenged. (5) The fine slurry from the secondary classification is further refined, and the coarse slurry from the secondary classification is returned to the vertical mill. (6) The scavenging tailings from step (4) are added to flotation reagents and floated by a flotation machine; the scavenging concentrate is returned to the mixed roughing in step (3); the scavenging tailings are floated by a flotation machine to obtain a froth product, and the obtained froth product is returned to the vertical mill in step (5); (7) The fined tailings from step (5) are returned to the mixed coarse separation in step (3); The flotation reagents in step (6) are Z200, butyl xanthate, CaO and pine oil.

2. The method for recovering lean intergrowths from copper tailings according to claim 1, characterized in that, In step (2), the particle size of the fine slurry in the primary classification is 68%-73% for -200 mesh.

3. The method for recovering lean intergrowths from copper tailings according to claim 1 or 2, characterized in that, In step (6), the flotation reagents are: Z200 dosage of 7-18 g / t feed, butyl xanthate dosage of 5-20 g / t feed, CaO dosage of 200-750 g / t feed, and pine oil dosage of 3-20 g / t feed.

4. The method for recovering lean intergrowths from copper tailings according to claim 3, characterized in that, The flotation machine used in step (6) is a shallow trough flotation machine; the shallow trough flotation machine includes a tank body, a stirring shaft, a stator ring fixed concentrically with the stirring shaft, a circulation cylinder, and a bottom plate with through holes; a support rod is provided between the bottom plate and the bottom of the tank body to form a circulation channel between the bottom plate and the bottom of the tank; the circulation cylinder is set between the bottom plate and the stator ring; the stator ring, circulation cylinder, and bottom plate are fixed concentrically; the stator ring is formed by the stator being fixed circumferentially around the stirring shaft, and the stator ring is set in the middle of the tank body; a foam collection tank is provided inside the tank body, the foam collection tank is an annular tank, and a foam discharge pipe is connected to the tank body to pass through the tank body and discharge the foam product outside the flotation machine.

5. The method for recovering lean intergrowths from copper tailings according to claim 4, characterized in that, An intermediate tank is set in front of the shallow trough flotation machine. The reagents required for flotation are added into the intermediate tank through a pipeline and fully mixed with the slurry before being added to the shallow trough flotation machine.

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