A column mill combined process for zinc metal recovery from lead-zinc flotation tailings

Abstract

This invention relates to a column-flotation combined process for zinc metal recovery from lead-zinc flotation tailings. The process includes the following steps: (1) preparing the feed product from lead-zinc flotation tailings with zinc metal recovery value; (2) performing primary roughing of the feed product using a CPT flotation column to obtain primary roughing concentrate and primary roughing tailings; (3) classifying the primary roughing tailings to obtain a fine-grained product (-0.074 mm) and a coarse-grained product (+0.074 mm); (4) performing secondary roughing of the coarse-grained product using a JJF flotation machine to obtain secondary roughing concentrate and secondary roughing tailings; (5) regrinding the secondary roughing concentrate to obtain regrinding pulp; (6) combining the primary roughing concentrate and regrinding pulp and then performing cleaning using a CPT flotation column to obtain zinc concentrate and middlings; (7) scavenging the secondary roughing tailings using a JJF flotation machine to obtain scavenged concentrate and process tailings. This invention features a short process flow, good flotation performance, and low economic cost.

Description

Technical Field

[0001] This invention relates to the field of resource secondary utilization and mineral processing technology, and in particular to a column-mill combined process for the recovery of zinc metal from lead-zinc flotation tailings. Background Technology

[0002] Most flotation tailings from concentrators, both domestically and internationally, are stored in tailings ponds. These tailings not only cause significant environmental problems but also, due to the unique properties of the ore and defects in the concentrator process, are often rich in valuable elements such as lead, zinc, silver, sulfur, and iron. Zinc, in particular, is prone to mud formation and is closely related to sulfur dissemination, resulting in high content in the tailings. A lead-zinc concentrator in Gansu Province produces 1.4 million tons of tailings annually, with approximately 5,000 tons of zinc metal lost in the tailings each year. This tailings have high recovery value. If the zinc in these tailings can be recovered, it will not only effectively improve the company's economic benefits but also have significant reference and promotional value for the comprehensive utilization of tailings resources in similar mines both domestically and internationally.

[0003] The current lead-zinc ore production at the concentrator uses a lead-zinc preferential flotation process. The flotation equipment used is the same model but different specifications of JJF flotation machine. The laboratory took an appropriate amount of representative tailings ore sample to conduct zinc flotation tests. After two roughing processes, one scavenging process, and three cleaning processes, the zinc concentrate grade was 31%, and the zinc recovery rate was 45%. The process involves many cleaning processes and the zinc recovery rate is relatively low. To further explore the possibility of improving the utilization rate of zinc resources in this tailings, particle size analysis was conducted. The results showed that zinc metal was mainly lost in the +0.074mm and -0.038mm particle sizes. This bipolar metal loss is a common problem in mineral processing because the loss of coarse-grained minerals is usually due to the failure of zinc minerals to be liberated. It is necessary to increase the grinding fineness to enhance recovery. Although regrinding is beneficial to the liberation and recovery of coarse-grained minerals, it will exacerbate the over-grinding of fine-grained minerals. However, the flotation machine has poor selectivity for fine-grained minerals. Moreover, since this is a tailings resource with a low feed grade, it is necessary to increase the number of cleaning cycles to obtain a higher grade zinc concentrate. However, increasing the number of cleaning cycles will increase the loss of fine-grained minerals. It is difficult to achieve both the zinc grade and recovery rate in the zinc concentrate.

[0004] The selection of flotation equipment plays a crucial role in the effectiveness of flotation technology. Flotation equipment is divided into two main categories: flotation machines and flotation columns. When separating coarse-grained minerals, flotation machines suspend the minerals by increasing the impeller stirring intensity, resulting in strong collection ability. However, they have poor selectivity for fine-grained minerals. In contrast, flotation columns produce a more stable pulp with less agitation, making them suitable for the flotation of fine-grained minerals. They have the advantage of a high concentrate enrichment ratio, but their collection ability for coarse-grained minerals is weak.

[0005] There are many types of flotation columns, with differences mainly in column height, mineralization method, bubble formation method, number of cells, and bubble generator position. For example, based on mineralization method, they can be classified as countercurrent-collision mineralization type, cyclone-collision mineralization type, tubular or centrifugal-collision mineralization type, and a combination of multiple mineralization methods. Based on bubble formation method, they can be classified as air-splitting type, air-jet type, and gas-liquid mixed type. Over the years, improvements and innovations have been made to address the advantages and disadvantages of different column shapes, bubble generators, bubble formation methods, and mineralization methods, resulting in many excellent flotation columns, such as the Jameson flotation column, the FCSMC cyclone-static microbubble flotation column, the CPT flotation column, and the CCF flotation column. In practical applications, the choice of flotation column should be based on the properties of the ore being processed and the advantages of each type. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a column-mill combined process for the recovery of zinc metal from lead-zinc flotation tailings, which has a short process, good flotation index, and low economic cost.

[0007] To address the aforementioned problems, the present invention provides a column mill combined process for zinc metal recovery from lead-zinc flotation tailings, comprising the following steps: (1) Stir and adjust the lead-zinc flotation tailings with zinc metal recovery value to a feed product concentration of 28%~30%. (2) The feed product is subjected to primary roughing of zinc using a CPT flotation column to obtain primary roughing concentrate and primary roughing tailings; (3) The tailings from the primary roughing process are classified to obtain a fine-grained product of -0.074 mm and a coarse-grained product of +0.074 mm; the fine-grained product is returned to the primary roughing process in step (2). (4) The coarse-grained product is subjected to secondary roughing using a JJF flotation machine to obtain secondary roughing concentrate and secondary roughing tailings; (5) The secondary roughing concentrate is regrinded to control the grinding fineness to 80%-0.038mm to obtain regrinding slurry; (6) The primary roughing concentrate and the regrinding slurry are combined and then cleaned using a CPT flotation column to obtain zinc concentrate and middlings; the middlings are returned to step (3) for grading. (7) The secondary roughing tailings are scavenged using a JJF flotation machine to obtain scavenged concentrate and process tailings; the scavenged concentrate is returned to step (4).

[0008] In step (1), the zinc grade of the lead-zinc flotation tailings is 0.2% to 0.5%.

[0009] Compared with the prior art, the present invention has the following advantages: 1. This invention addresses the issue that zinc metal loss in mine flotation tailings is largely due to the bipolar distribution of the minerals. Utilizing the advantages and disadvantages of flotation columns and flotation machines, it proposes using flotation columns and flotation machines to pre-enrich fine-grained and coarse-grained zinc minerals respectively. Simultaneously, taking advantage of the short flotation column flow and high flotation speed, the fine-grained rougher concentrate and coarse-grained flotation concentrate are combined after regrinding and then finely concentrated in a single flotation column to obtain zinc concentrate.

[0010] 2. The CPT flotation column used in this invention is a jet-countercurrent-microbubble type flotation column. The cavity resonant bubbler in the flotation column generates microbubbles using the jet principle. The microbubbles have a small diameter and can selectively precipitate preferentially on the surface of hydrophobic minerals. The area around the microbubbles is mostly in a laminar flow state, which makes it easy for fine materials to be adsorbed and not easy to fall off. In addition, because the particles and bubbles move in opposite directions in the countercurrent flotation column, the absolute speed of their movements is small and the degree of turbulence is low. This not only provides a large number of opportunities for bubbles to collect mineral particles, but also makes it difficult for coarse-grained minerals to fall off the bubbles. Compared with co-current and swirl flotation columns, it has a significant advantage in collecting coarse-grained minerals.

[0011] 3. The process of this invention for recovering zinc resources from tailings has the advantages of shorter process, lower cost and better flotation index compared with conventional full flotation machine process. Attached Figure Description

[0012] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0013] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0014] like Figure 1 As shown, a column mill combined process for zinc metal recovery from lead-zinc flotation tailings includes the following steps: (1) Stir and adjust the lead-zinc flotation tailings with zinc metal recovery value and zinc grade of 0.2%~0.5% to a feed product concentration of 28%~30%; (2) A CPT flotation column (manufactured by CPT Corporation of Canada) is used to perform primary roughing of zinc in the feed product to obtain primary roughing concentrate and primary roughing tailings; (3) The tailings from the primary roughing process are classified to obtain a fine-grained product of -0.074mm and a coarse-grained product of +0.074mm; the fine-grained product is returned to the primary roughing process in step (2). (4) A JJF flotation machine is used to perform secondary roughing on the coarse-grained product to obtain secondary roughing concentrate and secondary roughing tailings; (5) The secondary roughing concentrate is regrinded to control the grinding fineness at 80%-0.038mm to obtain regrinding slurry; (6) The primary roughing concentrate and regrinding pulp are combined and then cleaned using a CPT flotation column to obtain zinc concentrate and middlings; the middlings are returned to step (3) for classification. (7) The JJF flotation machine is used to scavenger the secondary roughing tailings to obtain scavenged concentrate and process tailings; the scavenged concentrate is returned to step (4).

[0015] Working Principle: Addressing the low zinc grade (0.2%~0.5%) and bipolar zinc particle size distribution in flotation tailings, this process combines the advantages of both flotation machines and flotation columns, particularly the jet-countercurrent-microbubble type CPT flotation column, which exhibits excellent collection performance for both coarse and fine-grained minerals. First, a CPT flotation column is used for pre-roughing to enrich some fine-grained zinc. The tailings from the first roughing are then classified. The fine-grained graded product is returned to the roughing process, while the coarse-grained product undergoes secondary roughing and scavenging using a JJF flotation machine. Then, leveraging the short flow path and high flotation speed of the CPT flotation column, the enriched fine-grained coarse concentrate and the regrinded coarse-grained coarse concentrate are combined and subjected to a single cleaning process using the CPT flotation column to obtain zinc concentrate. Simultaneously, the middlings from the cleaning process are returned to the classification operation, and the scavenged concentrate is returned to the secondary roughing process.

[0016] Example 1 A certain lead-zinc flotation tailings, with a zinc grade of 0.35%, is processed using... Figure 1 The process flow shown involves beneficiation and recovery of the tailings. Specific reagent conditions are as follows: 1000 g / t lime, 150 g / t copper sulfate, and 40 g / t butyl xanthate are added during the primary roughing stage. # 20g / t of oil, 15g / t of butyl xanthate added in the second roughing stage, 2 # Add 5g / t of oil, 5g / t of butyl xanthate during scavenging, and 500g / t of lime during fine selection.

[0017] The conventional approach uses the same reagent conditions as above, with flotation machines used for roughing, scavenging, and cleaning. Zinc concentrate is obtained through two roughing processes, one scavenging process, and three cleaning processes.

[0018] The comparison of the test indicators obtained using the two process schemes above is shown in Table 1.

[0019] Table 1 Comparison of test results in Example 1 As shown in Table 1, the zinc concentrate obtained by the process of this invention has better grade and recovery rate than conventional processes, and the process structure is shorter and easier to implement.

[0020] Example 2 A copper-zinc flotation tailings ore, with a zinc grade of 0.25%, is processed using... Figure 1The process flow shown involves beneficiation and recovery of the tailings. Specific reagent conditions are as follows: 1000 g / t lime, 100 g / t copper sulfate, and 30 g / t butyl xanthate are added during the primary roughing stage. # Oil 15g / t, butyl xanthate 10g / t added in the second roughing stage, 2 # Add 5g / t of oil, 5g / t of butyl xanthate during scavenging, and 500g / t of lime during fine selection.

[0021] The conventional approach uses the same reagent conditions as above, with flotation machines used for roughing, scavenging, and cleaning. Zinc concentrate is obtained through two roughing processes, one scavenging process, and three cleaning processes.

[0022] The comparison of the test indicators obtained using the two process schemes above is shown in Table 2.

[0023] Table 2 Comparison of test results in Example 2 As shown in Table 2, compared with conventional process schemes, the process of this invention not only has a shorter process structure and is easier to implement, but also has better zinc flotation indicators.

[0024] Example 3 A certain copper-lead-zinc polymetallic flotation tailings, with a zinc grade of 0.5%, is processed using... Figure 1 The process flow shown involves beneficiation and recovery of the tailings. Specific reagent conditions are as follows: 1000 g / t lime, 200 g / t copper sulfate, and 50 g / t butyl xanthate are added during the primary roughing stage. # 20g / t of oil, 15g / t of butyl xanthate added in the second roughing stage, 2 # Add 5g / t of oil, 5g / t of butyl xanthate during scavenging, and 500g / t of lime during fine selection.

[0025] The conventional approach uses the same reagent conditions as above, with flotation machines used for roughing, scavenging, and cleaning. Zinc concentrate is obtained through two roughing processes, one scavenging process, and three cleaning processes.

[0026] The comparison of the test indicators obtained using the two process schemes above is shown in Table 3.

[0027] Table 3 Comparison of test results in Example 3 As shown in Table 3, compared with conventional process schemes, the process of this invention not only has a shorter process structure and is easier to implement, but also has better zinc flotation indicators.

Claims

1. A column mill combined process for zinc metal recovery from lead-zinc flotation tailings, comprising the following steps: (1) Stir and adjust the lead-zinc flotation tailings with zinc metal recovery value to a feed product concentration of 28%~30%. (2) The feed product is subjected to primary roughing of zinc using a CPT flotation column to obtain primary roughing concentrate and primary roughing tailings; (3) The tailings from the primary roughing process are classified to obtain a fine-grained product of -0.074 mm and a coarse-grained product of +0.074 mm; the fine-grained product is returned to the primary roughing process in step (2). (4) The coarse-grained product is subjected to secondary roughing using a JJF flotation machine to obtain secondary roughing concentrate and secondary roughing tailings; (5) The secondary roughing concentrate is regrinded to control the grinding fineness to 80%-0.038mm to obtain regrinding slurry; (6) The primary roughing concentrate and the regrinding slurry are combined and then cleaned using a CPT flotation column to obtain zinc concentrate and middlings; the middlings are returned to step (3) for grading. (7) The secondary roughing tailings are scavenged using a JJF flotation machine to obtain scavenged concentrate and process tailings; the scavenged concentrate is returned to step (4).

2. The column mill combined process for zinc metal recovery from lead-zinc flotation tailings as described in claim 1, characterized in that: In step (1), the zinc grade of the lead-zinc flotation tailings is 0.2% to 0.5%.

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