A process for reducing the copper content in the flotation tailings of copper smelting slag

Abstract

The present invention discloses a method for reducing the copper content in the flotation tailings of copper smelting slag, which comprises the following steps: S1, ball milling operation; S2, first roughing operation; S3, second roughing operation; S4, cleaning operation; S5, full-stage classification of scavenging; S6, cut-off classification; S7, directly discarding the undersize part as tailings and regrounding the oversize part; S8, regrinding operation; S9, first re-selection operation. It is applicable to different types of slag such as smelting slag, converter slag and electric furnace slag. After obtaining the roughing product, the present invention classifies each operation point in the full stage of scavenging, measures the different copper grades of each particle size, selects the operation points and particle sizes with better recovery effect for cut-off classification, and the undersize tailings can be directly discarded, while the oversize tailings are reground and re-selected. The present invention can not only greatly reduce the copper content in copper smelting slag, avoid waste of resources, but also greatly reduce the recirculation amount of middlings, making the flotation system operate more stably.

Description

Technical Field

[0001] The present invention relates to the technical field of ore dressing engineering, and particularly relates to a method for reducing copper content in copper smelting slag tailings. Background Art

[0002] Mineral resources are an important material basis for the sustainable growth of the national economy, and the demand for mineral resources in the development of human society is increasing day by day. At present, domestic copper smelting raw materials are extremely scarce, and most of the copper smelting production depends on imported copper concentrates. A large amount of slag will be generated during the copper smelting process. The copper content in these copper smelting slags is usually between 1% and 5%. If these slags cannot be effectively recovered, it will not only cause environmental pollution but also result in a waste of copper resources. Therefore, fully recycling and reusing these slags is of great significance for saving resources and protecting the environment.

[0003] Generally speaking, the smelting waste slag generated in the copper smelting process is a kind of "artificial ore" in a broad sense, and common ones include smelting slag, converter slag and electric furnace slag. At present, the flotation process for recovering copper smelting slag in China is basically "two-stage roughing + multiple-stage cleaning + multiple-stage scavenging", supplemented by a regrinding process for middlings, and the copper content in the flotation tailings is used as the standard for its effective recovery. Among them, smelting slag is relatively common, and its flotation difficulty is often greater. According to statistics, the copper grade of the flotation tailings of copper smelting slag in China is about 0.35%, which is equivalent to the original ore grade of some domestic copper mines, resulting in serious resource waste. Even for slag dressing plants with relatively mature technology and management, the copper content in their slag dressing tailings is about 0.25%. The flotation difficulty of converter slag and electric furnace slag is relatively small, and the copper content in their tailings can be stabilized at about 0.22%. However, with the continuous increase of the import pressure of domestic copper resources, it is still of great practical significance to further reduce the copper content in the slag dressing tailings.

[0004] Generally speaking, the most direct factor affecting the copper content in the slag dressing tailings is the grinding fineness. The lower the grinding fineness, the lower the copper content in the slag dressing tailings shows a decreasing trend. At present, in actual production, the fineness of the slag after being ground in the front-end ball milling operation is generally between 70% and 80%, and it is difficult to grind it finer. Even if a long-term front-end grinding test with operability is carried out in the laboratory, although the copper content in the tailings is significantly reduced, the middling circulation rate increases rapidly, seriously affecting the balance and stability of the overall flotation system.

[0005] At present, there are also many solutions for further reducing the copper content in the copper smelting slag tailings. Among them, the grinding fineness of the smelting slag has the greatest impact on the copper content in the tailings. Usually, the "stage grinding and stage separation" process and the "middling regrinding and reseparation" process can be adopted, supplemented by a magnetic separation process.

[0006] The Chinese invention patent application with the publication number CN202011598996.2 discloses a method for comprehensively recovering copper minerals and iron minerals from copper converter slag. It uses a vertical mill to grind finely to improve the iron grade of iron concentrate, and uses two ball mills for staged grinding and flotation. The Chinese invention patent application with the publication number CN202010017882.8 discloses a copper smelting slag beneficiation method, which performs secondary grinding on the coarse part of the concentrate tailings to further separate copper and iron minerals to improve the grades of copper minerals and iron minerals. The Chinese invention patent application with the publication number CN201811351330.X discloses a method for stepwise recovering metallic copper, copper sulfide and iron minerals from copper converter slag. It uses a vertical mill for regrinding of magnetic rough concentrate to improve the grade of iron concentrate. The main use of the vertical mills adopted in the above-mentioned invention patent applications is to further separate copper and iron minerals in the beneficiation operation to improve the grades of copper minerals and iron minerals, and there is no effective reduction in the copper content of flotation tailings.

[0007] The Chinese invention patent application with the publication number CN201910407432.7 discloses a slag beneficiation system for reducing the copper content of tailings and its application. It uses three ball mills for fine grinding operations in two flotation systems, takes the scavenging tailings operation of one system as the feed for the regrinding operation, and performs flotation in the second system after regrinding. It belongs to the staged grinding and staged separation process.

[0008] The Chinese invention patent application with the publication number CN201810985250.3 discloses a stepped rapid flotation process for copper converter slag beneficiation, and the Chinese invention patent application with the publication number CN201810798352.4 discloses a beneficiation method for copper smelting slag. Both of the above methods adopt the staged grinding and staged separation process with two ball mills to obtain a part of easily floatable copper minerals as copper concentrate in advance. The Chinese invention patent application with the publication number CN201110275028.2 discloses a magnetic flotation combined beneficiation method for recovering copper from copper converter slag, which uses two-stage grinding in a ball mill, and obtains and uses the non-magnetic part of the return sand from the first-stage grinding in advance as copper concentrate, but essentially still belongs to the staged grinding and staged separation process.

[0009] The beneficiation operations of these types of invention patent applications use multi-stage ball mills for staged flotation. This process can preferentially obtain easily floatable copper minerals, thereby reducing the subsequent flotation pressure, but it is not very helpful for reducing the copper content of tailings.

[0010] The Chinese invention patent application with the publication number CN201810265692.0 discloses a beneficiation process for treating the floatability of slag intermediate ore, which performs regrinding on the scavenging concentrate. The Chinese invention patent application with the publication number CN201510997638.1 discloses a beneficiation process for flotation recovery of copper from copper smelting slag, which performs regrinding on the concentrate tailings and scavenging concentrate of the second system by returning them to the grinding operation. The Chinese invention patent application with the publication number CN201410550736.6 discloses a copper slag beneficiation process, which uses a vertical mill to perform regrinding on the copper rough concentrate of the second roughing operation to improve the dissociation degree of copper minerals, and then effectively recover this part of copper minerals. The above-mentioned types of invention patents perform regrinding and re-selection on the intermediate ore obtained in the flotation system. This process can fully dissociate some of the flotation intermediate ore, resulting in a certain reduction in the copper content of the tailings. However, the inventor found that the reduction value of the copper content in the final flotation tailings after regrinding the intermediate ore is only about 0.01 percentage points. Moreover, the fine particles after regrinding and dissociation often mostly circulate in the flotation system, being neither easy to be discharged with the concentrate nor easy to fall into the tailings, ultimately increasing the intermediate ore amount and the pressure of the system load rate.

[0011] The Chinese invention patent application with the publication number CN201510015815.1 discloses a method for separating copper from electric furnace slag. After the rough scavenging operation, the magnetic separation tailings are discarded using magnetic differences, while a large amount of magnetic separation concentrate still needs to be regrinded and floated. This invention patent performs separation according to the copper-iron dissemination characteristics in the slag, but this process has great limitations on the types of slag. The dissemination particle sizes of useful minerals in different types of slag are quite different. If the copper-iron minerals are simply disseminated, the copper content in non-magnetic minerals must be relatively high, so it is impossible to discard the magnetic separation tailings in advance. Summary of the Invention

[0012] The present invention solves the deficiencies of the prior art and provides a method for reducing the copper content in the flotation tailings of copper smelting slag, and this method is applicable to different types of slag such as smelting slag, converter slag, and electric furnace slag. This method can, without changing the fineness of the front-end grinding, after obtaining the roughing product, perform particle size classification of the products at each operation point in the entire scavenging stage at a particle size of 0.045 mm, measure the different copper grades of each particle size, compare the copper content of the tailings at different operation points with that of the final tailings at a particle size of -0.045 mm, perform truncated classification at a particle size of 0.045 mm on the shortest process action point with a copper percentage difference of less than 0.015, directly discard the tailings under the sieve, and perform regrinding and re-selection on the tailings above the sieve. This process can not only greatly reduce the copper content in the flotation tailings of copper smelting slag, avoid waste of resources, but also greatly reduce the intermediate ore circulation amount, making the flotation system operate more stably.

[0013] The technical solution adopted by the present invention is as follows: A method for reducing the copper content in the flotation tailings of copper smelting slag, comprising the following steps: S1, ball milling operation: After the smelting slag enters the mill and is ground finely, a pulp with a predetermined fineness is obtained; S2, first roughing operation: The pulp ground finely in S1 is subjected to the first roughing operation, and a regulator, a collector, and a foaming agent are added in sequence to obtain rough concentrate 1 and first roughing tailings respectively. The rough concentrate enters the cleaning system, and the first roughing tailings enter the second roughing operation; S3, second roughing operation: The first roughing tailings obtained in S2 are subjected to the second roughing operation, and a collector and a foaming agent are added in sequence to obtain rough concentrate 2 and second roughing tailings respectively. The rough concentrate 2 enters the cleaning system, and the second roughing tailings enter the scavenging operation; S4, cleaning operation: The rough concentrate 2 obtained in S3 enters the cleaning operation, and 3 times of concentrate operations are carried out according to the copper grade of the rough concentrate 2. The rough concentrate 1 enters the third cleaning system to obtain copper concentrate and 3 cleaning tailings respectively. The cleaning tailings are returned to the upper operation in sequence; S5, scavenging whole-stage classification: The second roughing tailings obtained in S3 are subjected to three scavenging operations to obtain middlings 1, middlings 2, middlings 3 and scavenging tailings 1, scavenging tailings 2, scavenging tailings 3 respectively. The above-mentioned operation points are classified by multiple particle sizes, and the copper grades of different particle sizes at each operation point are measured; S6, cut-off classification: Based on the data obtained by measurement in S5, determine the position of the cut-off classification operation in the scavenging; S7, directly discard the undersize part after the cut-off classification as tailings, and re-grind the oversize part; S8, re-grinding operation: The oversize part obtained in S7 is subjected to vertical mill re-grinding operation, and the re-grinding fineness is more than 90% of -0.045mm; S9, first re-selection operation: The oversize part after re-grinding in S8 is re-selected, and a regulator, a collector, and a foaming agent are added in sequence. This re-selection operation only needs to be carried out once, and the obtained re-selected copper concentrate enters the first cleaning operation, and the re-selected tailings are discarded.

[0014] As a further improvement of the present invention, in the step S6, according to the particle size distribution law of the scavenging operation, ensuring that the copper grade of the particle size at the cut-off classification position is less than 0.015 percentage points compared with the copper grade of the conventional tailings particle size can better greatly reduce the copper content in the tailings and achieve resource conservation in the scavenging operation.

[0015] As a further improvement of the present invention, in the step S8, when the copper grade of the re-selected copper concentrate > 5%, it can enter the second cleaning operation; when ≤ 5%, it enters the first cleaning operation, which can ensure that the copper grade of the copper concentrate meets the normal standard requirements.

[0016] As a further improvement of the present invention, the regulator is sodium sulfide, the collector is butyl xanthate, and the foaming agent is No. 2 oil.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. The present invention can greatly reduce the copper content in the slag-selected copper tailings.

[0019] 2. Without the requirement of improving the grinding effect of the front-end ball milling, the present invention can still ensure the further reduction of copper content in the flotation tailings.

[0020] 3. By measuring the multi-grade copper grades at each action point of the scavenging system, the separation effects of different action points and different particle sizes in the scavenging system can be accurately judged, so as to determine the position and particle size of the cut-off classification operation, and the undersize part that has been fully recovered after classification is discharged in advance. This not only greatly reduces the copper content in this part of the tailings, but also reduces the unnecessary redundant load in the scavenging system, and also saves a part of the energy consumption of the scavenging operation.

[0021] 4. The smelting slag after re-grinding by the vertical mill only needs to be separated once, without the need to add a series of scavenging systems. In the slag separation plant, the saved scavenging flotation machines can be directly used as the flotation machines for re-separation, without adding additional expenses for flotation machines to the slag separation plant.

[0022] 5. For the slag separation plant originally adopting the process of re-grinding of middlings, the vertical mill for re-grinding of middlings can be used as the re-grinder for the scavenging operation, without adding additional expenses for vertical mills to the slag separation plant.

[0023] 6. The present invention can freely change the position of the cut-off classification operation according to the properties of the smelting slag and the mechanical capacity, and by referring to the particle size and copper content of the products at different action points. That is, if the roughing effect is good, and the copper content in the second roughing tailings and the final copper ore separated from the slag is lower than 0.015 percentage points, the cut-off classification can be carried out at the second roughing position. It has extremely high flexibility and strong applicability.

[0024] 7. The present invention is not affected by the discomfort caused by different properties of the smelting slag and has extremely wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a conventional flow chart of the slag separation site.

[0026] Figure 2 It is a schematic diagram of the present invention.

[0027] Figure 3 It is a schematic diagram of Example 2 disclosed by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] A method for reducing the copper content in the flotation tailings of copper smelting slag includes the following steps:

[0030] S1, ball milling operation: The smelting slag enters the mill and is ground into a slurry with a predetermined fineness.

[0031] S2, First roughing operation: The pulp after grinding in S1 is subjected to a first roughing operation, and a regulator, a collector, and a frother are added in sequence to obtain rough concentrate 1 and first rough tailings respectively. The rough concentrate enters the cleaning system, and the first rough tailings enter the second roughing operation;

[0032] S3, Second roughing operation: The first rough tailings obtained in S2 are subjected to a second roughing operation, and a collector and a frother are added in sequence to obtain rough concentrate 2 and second rough tailings respectively. The rough concentrate 2 enters the cleaning system, and the second rough tailings enter the scavenging operation;

[0033] S4, Cleaning operation: The rough concentrate 2 obtained in S3 enters the cleaning operation. According to the copper grade of the rough concentrate 2, three cleaning operations are carried out. The rough concentrate 1 enters the three - stage cleaning system to obtain copper concentrate and three cleaning tailings respectively. The cleaning tailings are returned to the upper - stage operations in sequence;

[0034] S5, Full - stage classification in scavenging: The second rough tailings obtained in S3 are subjected to three scavenging operations to obtain middlings 1, middlings 2, middlings 3 and scavenging tailings 1, scavenging tailings 2, scavenging tailings 3 respectively. The above - mentioned operation points are classified by a particle size of 0.045 mm, and the copper grades of different particle sizes at each operation point are measured. The reason for choosing the 0.045 - mm particle - size screening: Coarser than 0.045 mm particle size will cause too much copper loss after cut - off classification. Finer than 0.045 mm particle size will theoretically reduce the copper content under the cut - off classifier, but finer screen holes are prone to blockage, which affects the throughput, requires more frequent replacement, and has a higher cost, which is not conducive to the manifestation of economic value.

[0035] S6, Cut - off classification: Based on the data obtained by measurement in S5, determine the position of the classification operation in the scavenging system;

[0036] S7, Discard the undersize part directly as tailings, and re - grind the oversize part;

[0037] S8, Re - grinding operation: The oversize part obtained in S7 is re - ground by a vertical mill, and the re - grinding fineness is more than 90% of the particle size of the classification operation in S6;

[0038] S9, First re - separation operation: The oversize part after re - grinding in S8 is re - separated, and a regulator, a collector, and a frother are added in sequence. The re - separated copper concentrate obtained is sent to the first cleaning operation, and the re - separation tailings are discarded.

[0039] To further understand the present application, the copper - reducing process of copper - smelting slag from a certain factory is specifically selected.

[0040] Example 1,

[0041] In a copper - smelting slag separation workshop in Inner Mongolia, the original ore copper grade is about 1.24%. The nature of the smelting slag is electric - furnace slag, and the particle - size distribution law of the scavenging operation is measured. The specific indexes are shown in the table.

[0042] Measurements were carried out on Example 1, and the specific data are shown in Table 1.

[0043] Table 1 Distribution law table of scavenging operation in Example 1

[0044]

[0045] It can be seen from Table 1 of Example 1 that the copper content in the copper tailings obtained finally by the smelting slag beneficiation operation under the conventional process is 0.187%. After the copper tailings are classified by the -0.045mm particle size, the copper content in the undersize tailings drops to 0.156%. Even the copper content in the first scavenging tailings lacking two-stage scavenging is only 0.168%. This copper grade is 0.012 percentage points higher than the grade of the final copper tailings and 0.019 percentage points lower than the copper content in the conventional tailings. Therefore, the position of the truncated classification operation is set at the first scavenging tailings for closed-circuit tests.

[0046] The results of the closed-circuit tests are shown in Table 2.

[0047] Table 2 Comparative results of closed-circuit tests in Example 1

[0048]

[0049] The closed-circuit results in Table 2 of Example 1 show that the copper content in the copper tailings finally obtained by the inventive process is 0.183%, which is 0.031 percentage points lower than that of the conventional process, and the effect is remarkable.

[0050] Example 2

[0051] In a beneficiation workshop of a smelting slag in Anhui, the copper grade of the raw ore is about 1.69%, and the nature of the smelting slag is smelting slag. The particle size distribution law of the scavenging operation is measured, and the specific indexes are shown in Table 3.

[0052] Table 3 Distribution law table of scavenging operation in Example 2

[0053]

[0054] It can be seen from Table 1 of Example 2 that the copper content in the copper tailings finally obtained by the smelting slag beneficiation operation under the conventional process is 0.260%. After the copper tailings are classified by the -0.045mm particle size, the copper content in the undersize tailings drops to 0.208%. At this time, it can be seen that the copper content of the -0.045mm particle size in the second roughing tailings is only 0.221%. In the case of lacking three-stage scavenging operations, it is 0.039 percentage points lower than that of the conventional copper tailings. Therefore, the position of the truncated classification operation is set at the second roughing tailings for closed-circuit tests.

[0055] The results of the closed-circuit tests are shown in Table 4.

[0056] Table 4 Comparative results of closed-circuit tests in Example 2

[0057]

[0058] The results of the closed - circuit in Table 4 of Example 2 show that the copper - containing selected copper tailings finally obtained by the inventive process contain 0.238% copper, which is 0.048 percentage points lower than that of the conventional process, and the effect is remarkable.

[0059] Those skilled in the art should be aware that the protection scope of the present invention is not limited to the above - mentioned embodiments, and various permutations, combinations and transformations can be made on the basis of the above - mentioned embodiments. Without departing from the spirit of the present invention, all transformations made to the present invention fall within the protection scope of the present invention.

Claims

1. A method for reducing copper content in copper smelting slag flotation tailings, comprising the following steps: S1, Ball milling operation: After the smelting slag enters the mill and is ground finely, pulp with a predetermined fineness is obtained. S2, First roughing operation: The pulp obtained from grinding in S1 is subjected to a first roughing operation. A regulator, a collector, and a frother are added in sequence to obtain rough concentrate 1 and first roughing tailings respectively. The rough concentrate enters the cleaning system, and the first roughing tailings enter the second roughing operation. S3, Second roughing operation: The first roughing tailings obtained from S2 are subjected to a second roughing operation. A collector and a frother are added in sequence to obtain rough concentrate 2 and second roughing tailings respectively. The rough concentrate 2 enters the cleaning system, and the second roughing tailings enter the scavenging operation. S4, Cleaning operation: The rough concentrate 2 obtained from S3 enters the cleaning operation. According to the copper grade of the rough concentrate 2, 1 - 2 more cleaning operations are carried out. According to the copper grade of the rough concentrate 1, the position where it enters the cleaning system is determined. Copper concentrate and 2 - 3 cleaning tailings are obtained respectively, and the cleaning tailings are returned to the upper operation in sequence. When the copper grade of the rough concentrate 1 > 5%, it can enter the second cleaning operation; when ≤ 5%, it enters the first cleaning operation, so as to ensure that the copper grade of the copper concentrate meets the normal standard requirements. S5, Full - stage classification in scavenging: The second roughing tailings obtained from S3 are subjected to at least three scavenging operations to obtain middlings 1, middlings 2, middlings 3 and scavenging tailings 1, scavenging tailings 2, scavenging tailings 3 respectively. Multi - grain - size classification is carried out at each of the above operation points, and the copper grades of different particle sizes at each operation point are measured. The measured particle sizes are 0.045 mm and 0.038 mm. S6, Cut - off classification: Based on the data obtained from the measurement in S5, the position and classification particle size of the classification operation in the scavenging are determined. According to the particle - size distribution law of the scavenging operation, ensuring that the copper grade of the particle size at the cut - off classification position is less than 0.01% compared with the copper grade of the conventional tailing particle size can better achieve resource conservation in the scavenging operation and can also greatly reduce the copper content in the tailings. The particle size of the cut - off classification operation is 0.045 mm or 0.038 mm. S7, The part passing through the sieve is directly discarded as tailings, and the part retained on the sieve is reground. S8, Regrinding operation: The part retained on the sieve obtained from S7 is subjected to vertical mill regrinding operation, and the regrinding fineness is 90 - 95% of the classification operation particle size in S6. S9, First re - selection operation: The part retained on the sieve after regrinding in S8 is re - selected. A regulator, a collector, and a frother are added in sequence. This re - selection operation only needs to be carried out once. The re - selected copper concentrate obtained enters the first cleaning operation, and the re - selected tailings are discarded.

2. A method for reducing the copper content in the flotation tailings of copper smelting slag according to claim 1, characterized in that The regulator is sodium sulfide, the collector is butyl xanthate, and the frother is No. 2 oil.

3. A method for reducing copper content in copper smelting slag flotation tailings according to claim 1 or 2, characterized in that The cut - off classification is based on the properties of the smelting slag and the mechanical capacity.

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