A method for pre-removal of magnetic pyrrhotite in polymetallic sulfide ore

Abstract

The application provides a method for pre-removing magnetic pyrite in a polymetallic sulfide ore, comprising the following steps: performing one-stage grinding and grading on the raw ore to obtain overflow products with a fineness of 75%-85% of the proportion of the-0.074 mm particle size; performing one-stage magnetic separation on the overflow products to obtain one-stage magnetic separation concentrate and one-stage magnetic separation tailings, which are fed into subsequent flotation operation; performing regrinding on the one-stage magnetic separation concentrate, controlling the fineness of the regrinding products to be 80%-90% of the proportion of the-0.043 mm particle size, and then performing two-stage magnetic separation to obtain two-stage magnetic separation concentrate and two-stage magnetic separation tailings, which are returned to the previous process for cyclic treatment. Through the synergistic regulation of stage grinding and gradient magnetic field strength, the application realizes efficient removal of magnetic pyrite, significantly reduces the entrainment loss of valuable metals in the magnetic products, and provides an efficient and feasible technical solution for solving the magnetic pyrite interference problem in the separation process of a complex polymetallic sulfide ore.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, and more specifically, to a method for the pre-removal of magnetite from polymetallic sulfide ores. Background Technology

[0002] Polymetallic sulfide ores are important non-ferrous metal resources, characterized by complex mineral compositions and often associated with a variety of minerals such as pyrrhotite, pyrite, cassiterite, brittle stibnite, and sphalerite. The close intermingling of these minerals and their uneven grain size distribution make beneficiation and separation extremely difficult. Among these, pyrrhotite (primarily pyrrhotite), a strongly magnetic sulfide mineral, exhibits significantly different magnetic properties and floatability in different mining areas and even at different locations within the same ore body due to its variable crystal structure and inconsistent iron-sulfur ratio. This makes it a key interfering factor affecting the efficient separation of major valuable minerals such as lead, zinc, and tin.

[0003] In existing technologies, for polymetallic sulfide ores containing pyrrhotite, preferential flotation or mixed flotation is typically used, followed by magnetic separation of the flotation tailings or middlings to recover or remove magnetic minerals. This "flotation first, then magnetic separation" process has drawbacks such as pyrrhotite interfering with the flotation of valuable minerals, a lengthy process, and complex reagent formulations. Although some processes include magnetic separation after grinding, these are mostly single-stage magnetic separations, which do not completely recover pyrrhotite intergrowths of valuable minerals. These intergrowths still have an adverse effect when they enter the flotation system, limiting further improvements in separation performance.

[0004] Therefore, developing a pretreatment process that can efficiently and deeply remove pyrrhotite before flotation and achieve full recovery of valuable metals has important industrial application value for optimizing the polymetallic sulfide ore beneficiation process and improving metal recovery rate and concentrate quality.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of pyrrhotite interfering with subsequent flotation, leading to a decline in separation indicators and complex process flow in existing technologies. This invention provides a method for the pre-removal of pyrrhotite from polymetallic sulfide ores. Through the coordinated control of staged grinding and gradient magnetic field strength, efficient removal of pyrrhotite is achieved, while significantly reducing the entrainment loss of valuable metals in magnetic products. This provides an efficient and feasible technical solution for solving the problem of pyrrhotite interference in the separation process of complex polymetallic sulfide ores.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A method for pre-removal of pyrrhotite from polymetallic sulfide ores includes the following steps: Step S1, Primary grinding and classification of raw ore: The polymetallic sulfide ore is subjected to primary grinding, and the grinding product is classified to obtain a classification overflow of a specified fineness; Step S2, First-stage magnetic separation and tailings disposal: The graded overflow is subjected to first-stage magnetic separation to obtain first-stage magnetic concentrate and first-stage magnetic tailings; Step S3, regrinding of the first-stage magnetic concentrate and further fine separation of the second-stage magnetic concentrate: The first-stage magnetic concentrate is regrinded and then subjected to second-stage magnetic separation to obtain second-stage magnetic concentrate and second-stage magnetic tailings.

[0008] Furthermore, the magnetic field strength of the first-stage magnetic separation in step S2 is lower than the magnetic field strength of the second-stage magnetic separation in step S3. The first-stage magnetic separation in step S2 is a medium magnetic field separation, and the second-stage magnetic separation in step S3 is a strong magnetic field separation.

[0009] Furthermore, in step S1, the fineness of the graded overflow is such that the content of -0.074mm particles accounts for 75% to 85%.

[0010] Furthermore, in step S1, lime is added as a modifier during the grinding process, and the amount of lime used is 2 kg / t to 4 kg / t based on the mass of the raw ore.

[0011] Furthermore, the magnetic field strength of the magnetic separation section in step S2 is 0.4 T to 0.7 T.

[0012] Furthermore, the magnetic field strength of the two-stage magnetic separation in step S3 is 0.8T~1.2T.

[0013] Furthermore, the magnetic field strength of the magnetic separation section in step S2 is 0.5T~0.6T.

[0014] Furthermore, the magnetic field strength of the two-stage magnetic separation in step S3 is 1.0T~1.2T.

[0015] Furthermore, in step S3, the fineness of the regrinding product is controlled so that the content of particles with a particle size of -0.043mm accounts for 80% to 90%.

[0016] Furthermore, the magnetic separation tailings described in step S2 are then used in subsequent flotation operations.

[0017] Furthermore, the tailings from the two-stage magnetic separation described in step S3 are returned to the grading operation in step S1 or the feed for the first-stage magnetic separation in step S2.

[0018] Further, in step S1, the polymetallic sulfide ore is either gold-tin-copper-lead-zinc polymetallic sulfide ore or tin-lead-zinc polymetallic sulfide ore, preferably gold-tin-copper-lead-zinc polymetallic sulfide ore. In the gold-tin-copper-lead-zinc polymetallic sulfide ore, by mass percentage, the gold content is 0.6g / t~0.8g / t, the tin content is 1.00%~1.30%, the copper content is 1.80%~2.10%, the lead content is 2.70%~3.10%, the zinc content is 8.00%~9.00%, and the iron content is 16.50%~17.00%. The pyrrhotite is mainly pyrrhotite, which contains both monoclinic and hexagonal crystal systems.

[0019] Furthermore, in step S2, a section of the magnetic separation tailings enters the subsequent lead-zinc flotation and cassiterite gravity separation operations.

[0020] Furthermore, in step S1, the polymetallic sulfide ore is a gold-tin-copper-lead-zinc polymetallic sulfide ore, and in step S2, the secondary magnetic separation concentrate is a high-grade magnetite concentrate, in which the tin grade is not higher than 0.22%.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention relates to a method for pre-removing pyrrhotite from polymetallic sulfide ores. This method utilizes a highly efficient magnetic separation process to pre-remove pyrrhotite (mainly pyrrhotite) before flotation. It employs a synergistic process of "first-stage coarse grinding and tailings removal, second-stage re-grinding and dissociation of coarse concentrate, and third-stage magnetic separation for fine selection." The magnetic field strength configuration is optimized based on the magnetic differences of pyrrhotite with different crystal systems. This maximizes the removal of pyrrhotite and pre-enrichment of valuable metals at the flotation front end, creating optimal conditions for subsequent flotation. This effectively reduces the interference of magnetic minerals on the subsequent flotation separation of valuable metals and improves the overall separation efficiency.

[0022] 2. The pre-removal method for pyrrhotite in polymetallic sulfide ores of the present invention significantly improves the removal efficiency of pyrite: through the gradient magnetic field design of "medium magnetic tailings removal - strong magnetic fine selection", in conjunction with stage grinding, the overall recovery rate of pyrrhotite in the magnetic separation system is greatly improved, and the magnetic concentrate yield is increased from 6% in the traditional process to 11.9%, effectively reducing the burden of subsequent flotation operations.

[0023] 3. The pre-removal method of pyrrhotite in polymetallic sulfide ores of the present invention achieves effective control of valuable metal loss: through the key step of regrinding, the intergrowth of pyrrhotite and valuable minerals is completely separated, which greatly reduces the entrainment of valuable metals in the secondary magnetic separation concentrate, and successfully controls the grade of valuable metals such as tin in the pyrrhotite concentrate to below 0.22%, thus solving the core pain point of metal loss in the magnetic separation process.

[0024] 4. The pre-removal method for pyrrhotite in polymetallic sulfide ores of the present invention addresses the differences in crystal properties. The process design explicitly considers the magnetic differences of pyrrhotite in different crystal systems. Through segmented magnetic separation intensity optimization, efficient and selective recovery of pyrrhotite of all crystal systems is achieved.

[0025] 5. The pre-removal method for magnetite in polymetallic sulfide ores of the present invention has strong process adaptability, and the specific process parameters can be flexibly adjusted according to the ore properties, thus possessing good industrial applicability and promotion prospects. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a process flow diagram of Embodiment 2 of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. 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. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0029] A method for pre-removal of pyrrhotite from polymetallic sulfide ores includes the following steps: Step S1, Primary grinding and classification of raw ore: The polymetallic sulfide ore is subjected to primary grinding, and the grinding product is classified to obtain a classification overflow of a specified fineness; primary grinding enables the initial liberation of most of the target minerals; Step S2, First-stage magnetic separation and tailings disposal: The graded overflow is subjected to first-stage magnetic separation to obtain first-stage magnetic concentrate and first-stage magnetic tailings; the first-stage magnetic tailings are then fed into subsequent flotation operations; Step S3, regrinding of primary magnetic concentrate and secondary magnetic separation: The primary magnetic concentrate is regrinded and then subjected to secondary magnetic separation to obtain secondary magnetic concentrate and secondary magnetic tailings; the secondary magnetic tailings are returned to the grading operation in step S1 or the primary magnetic feed in step S2.

[0030] Preferably, the fineness of the graded overflow in step S1 is that the content of -0.074mm particles accounts for 75% to 85%, including but not limited to 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, and 85%.

[0031] Preferably, lime is added as a modifier during the grinding process described in step S1. The amount of lime used is 2 kg / t to 4 kg / t (including but not limited to 2 kg / t, 2.5 kg / t, 3 kg / t, 3.5 kg / t, and 4 kg / t) based on the weight of the raw ore, to adjust the pH value of the slurry to 8 to 10 (including but not limited to 8, 8.5, 9, 9.5, and 10) to optimize the surface properties of the minerals and suppress some of the easily floating gangue.

[0032] Preferably, the magnetic field strength of the first stage magnetic separation in step S2 is lower than that of the second stage magnetic separation in step S3. The first stage magnetic separation in step S2 is a medium magnetic field magnetic separation, and the second stage magnetic separation in step S3 is a strong magnetic field magnetic separation. Through the gradient magnetic field design of "medium magnetic tailing-strong magnetic fine selection", in conjunction with stage grinding, the overall recovery rate of pyrrhotite in the magnetic separation system is greatly improved, and the magnetic concentrate yield is increased from 6% in the traditional process to more than 12%, effectively reducing the burden of subsequent flotation operations.

[0033] Preferably, the magnetic field strength of the magnetic separation section in step S2 is 0.4 T to 0.7 T, including but not limited to 0.4 T, 0.5 T, 0.6 T, and 0.7 T, with 0.5 T to 0.6 T being the most preferred.

[0034] Preferably, in step S2, a permanent magnet drum magnetic separator is used for the first stage of magnetic separation.

[0035] Preferably, the magnetic field strength of the two-stage magnetic separation in step S3 is 0.8T~1.2T, including but not limited to 0.8T, 0.9T, 1.0T, 1.1T, 1.2T, and preferably 1.0T~1.2T.

[0036] Preferably, the two-stage magnetic separation in step S3 uses a high-gradient magnetic separator.

[0037] Preferably, in step S3, the regrinding operation controls the fineness of the regrinded product to be such that the content of particles of -0.043mm accounts for 80%~90%, including but not limited to 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and 90%. Through the key step of regrinding, the intergrowth between pyrrhotite and valuable minerals is completely separated, resulting in a significant reduction in the entrainment of valuable metals in the secondary magnetic separation concentrate.

[0038] Preferably, the polymetallic sulfide ore in step S1 is a gold-tin-copper-lead-zinc polymetallic sulfide ore or a tin-lead-zinc polymetallic sulfide ore, with gold-tin-copper-lead-zinc polymetallic sulfide ore being preferred. The tailings from the first stage of magnetic separation in step S2 are then used for subsequent lead-zinc flotation and cassiterite gravity separation operations.

[0039] Preferably, in the gold-tin-copper-lead-zinc polymetallic sulfide ore described in step S1, the gold content, by mass percentage, is 0.6 g / t ~ 0.8 g / t (6 × 10⁻⁶ g / t). -5 %~8×10 -5 The content of tin is 1.00%~1.30%, copper is 1.80%~2.10%, lead is 2.70%~3.10%, zinc is 8.00%~9.00%, and iron is 16.50%~17.00%.

[0040] Preferably, the polymetallic sulfide ore in step S1 is a gold-tin-copper-lead-zinc polymetallic sulfide ore, and the secondary magnetic separation concentrate in step S2 is a high-grade magnetite concentrate, wherein the tin grade in the secondary magnetic separation concentrate is not higher than 0.22%.

[0041] The process parameters of this invention can be flexibly adjusted according to the properties of the ore, and it has good industrial applicability and promotion prospects.

[0042] The pyrrhotite is primarily pyrrhotite, which contains both monoclinic and hexagonal crystal systems. This invention considers the magnetic differences between pyrrhotite crystal systems and achieves efficient and selective recovery of pyrrhotite from all crystal systems through segmented magnetic separation intensity optimization.

[0043] In some specific embodiments, a method for pre-removing magnetite during the processing of gold-tin-copper-lead-zinc polymetallic sulfide ores includes the following steps: Step 1, primary grinding and classification of raw ore: The gold-tin-copper-lead-zinc polymetallic sulfide ore is subjected to primary grinding. The grinding product is classified by hydrocyclone to obtain an overflow product with a particle size of -0.074mm accounting for 75%~85%. Step 2, medium magnetic field magnetic separation and tailings removal: The overflow product obtained in Step 1 is fed into a first-stage magnetic separator and separated under a magnetic field strength of 0.4T~0.7T to obtain first-stage magnetic concentrate and first-stage magnetic tailings; Step 3, regrinding of the first-stage magnetic concentrate and high-gradient magnetic separation: The first-stage magnetic concentrate obtained in Step 2 is fed to a regrinding mill for fine regrinding, controlling the fineness of the regrinded product to be 80%~90% of the particles being -0.043mm, so as to fully dissociate the pyrrhotite and valuable minerals from each other; the regrinded slurry is fed into a high-gradient magnetic separator for high-gradient magnetic separation, and is then finely separated under a strong magnetic field of 0.8T~1.2T to obtain the second-stage magnetic concentrate and the second-stage magnetic tailings.

[0044] Preferably, in step one, lime is added as a modifier during grinding, with a dosage of 2-4 kg / t, to adjust the pH of the slurry to 8-10, thereby optimizing the surface properties of the minerals and inhibiting some of the easily floatable gangue.

[0045] The goal of the first-stage grinding in step one of this invention is to initially dissociate most of the target minerals and control the over-grinding of cassiterite.

[0046] In steps S3 and three of this invention, the tailings from the two-stage magnetic separation are rich in valuable metals that have been liberated from the intergrowth. They are returned to the grading operation in steps S1 and one or to the first-stage magnetic separation feed in steps S2 and two, forming a closed loop and achieving further recovery of valuable metals.

[0047] In steps S2 and step two of this invention, a medium magnetic field strength (0.4~0.7T) is used to prioritize the recovery of strongly magnetic monoclinic pyrrhotite and dissociated coarse-grained pyrrhotite, so as to avoid prematurely recovering a large amount of weakly magnetic hexagonal crystals and intergrowths, which would lead to severe entrainment.

[0048] In steps S3 and three of this invention, a strong magnetic field (0.8~1.2T) is used to ensure efficient collection of all pyrrhotite particles, including those with weak magnetic hexagonal crystals, which are fully dissociated after regrinding. At the same time, since the intergrowth has been greatly reduced, the inclusion of valuable metals under the strong magnetic field is controlled at an extremely low level.

[0049] This invention, through the gradient magnetic field design of "medium magnetic tailing-strong magnetic selection" and in conjunction with stage grinding, significantly improves the overall recovery rate of pyrrhotite in the magnetic separation system, increasing the magnetic concentrate yield from 6% in the traditional process to over 12%, effectively reducing the burden on subsequent flotation operations.

[0050] This invention completely separates the pyrrhotite and valuable minerals through the key regrinding step, which greatly reduces the entrainment of valuable metals in the secondary magnetic separation concentrate. The secondary magnetic separation concentrate is a high-grade pyrrhotite concentrate, which successfully controls the content of valuable metals such as tin in the pyrrhotite concentrate to below 0.22%, thus solving the core pain point of metal loss in the magnetic separation process.

[0051] This invention explicitly considers the magnetic differences of pyrrhotite with different crystal systems, and achieves efficient and selective recovery of pyrrhotite with all crystal systems by optimizing the intensity of segmented magnetic separation.

[0052] The mineral sample used in the embodiments and comparative examples of this invention is a complex tin-lead-zinc polymetallic sulfide ore, prepared by crushing, homogenizing, and fractionation. The main chemical composition of the ore sample is shown in Table 1. Mineral composition analysis shows that the main metallic minerals in the ore are cassiterite, galena, sphalerite, pyrrhotite, and pyrite, while the gangue minerals are mainly quartz and calcite. Among them, pyrrhotite exists in a mixture of monoclinic and hexagonal crystal systems, and its intergrowth relationship with valuable metallic minerals is complex.

[0053] Table 1. Main chemical composition of mineral samples used in the examples and comparative examples.

[0054] Example 1 A method for pre-removal of pyrrhotite from polymetallic sulfide ores includes the following steps: a. Primary grinding and classification of raw ore: The ore samples shown in Table 1 were crushed to -2 mm, and lime was added at a rate of 2.5 kg / t as a modifier before being fed into a Φ450×600 mm laboratory ball mill for primary grinding. The grinding product was classified by a Φ100 mm hydrocyclone, and the operating parameters were controlled to maintain the overflow concentration at 32%~35% and the fineness at 80% (-0.074 mm). The underflow was returned to the ball mill to form a closed loop, and the overflow was used as feed for subsequent magnetic separation.

[0055] b. First-stage medium-magnetic field magnetic separation: The overflow from the classification process is fed into a CRI-400 / 260 permanent magnet drum separator, and the background magnetic field strength is adjusted to 0.5 T. Separation is carried out under these conditions to obtain first-stage magnetic concentrate and first-stage magnetic tailings. After measurement and analysis, the yield of the first-stage magnetic concentrate is 15.2%, and the yield of the first-stage magnetic tailings is 84.8%. The sulfur content in the first-stage magnetic tailings decreased from 15.74% of the original ore to 5.85%, and this tailings are then used for subsequent flotation operations.

[0056] c. Regrinding of the first-stage magnetic separator concentrate and second-stage magnetic separation: The first-stage magnetic separator concentrate is fed into an XMO-240×90 conical ball mill for regrinding. The grinding concentration is 60%, and the grinding media are Φ10 mm steel balls. The regrinding time is controlled to achieve a product fineness of -0.043mm content of 85%. The regrinded product is processed using a SLon-100 periodic pulsating high-gradient magnetic separator, with the background magnetic field strength set to 1.0 T. After separation, second-stage magnetic separator concentrate and second-stage magnetic separator tailings are obtained.

[0057] The technical specifications obtained in Example 1 are as follows: Second-stage magnetic separation concentrate (final magnetite concentrate): yield 11.9% (compared to raw ore), sulfur grade 46.8%, tin grade 0.21%; Second-stage magnetic separation tailings: yield 3.3% (compared to raw ore), returned to the main process for grading; Tin recovery rate of the magnetic separation system: 1.98%.

[0058] Example 2 Example 2, based on Example 1, optimizes the magnetic separation process parameters of the present invention, including the following steps: a. Grinding and classification of raw ore in one stage: The operating conditions are the same as in Example 1, and the fineness of the classification overflow is controlled to be -0.074mm with a content of 78%.

[0059] b. First-stage medium-magnetic separation: The background magnetic field strength was adjusted to 0.6 T, and other conditions were the same as in Example 1. The concentrate yield of the first-stage magnetic separation was 13.5%, and the tailings yield of the first-stage magnetic separation was 86.5%.

[0060] c. Regrinding of the first-stage magnetic separator concentrate and second-stage magnetic separation: The fineness of the regrinding is controlled to be -0.043mm with a content of 88%. The background magnetic field strength of the second-stage magnetic separation is adjusted to 1.1 T. Other conditions are the same as in Example 1.

[0061] The technical specifications obtained in Example 2 are as follows: Second-stage magnetic separation concentrate (final magnetite concentrate): yield 12.2% (compared to raw ore), sulfur grade 47.2%, tin grade 0.17%; Second-stage magnetic separation tailings: yield 1.3% (compared to raw ore); Tin recovery rate of magnetic separation system: 1.65%.

[0062] Comparative Example 1 To verify the superiority of the present invention, a comparative example using a traditional single magnetic separation process was set up. The ore sample was the same as in Example 1, and after the same first-stage grinding and classification, magnetic separation was directly performed using a background field strength of 0.8 T, without any regrinding or re-separation process.

[0063] Comparative Example 1 Results Analysis: The technical indicators obtained by the traditional process are as follows: magnetic concentrate yield is 6.3% (for raw ore), sulfur grade of magnetic concentrate is 43.6%, tin grade of magnetic concentrate is 0.35%, and tin recovery rate of magnetic separation system is 1.76%.

[0064] Test case The technical indicators of Embodiments 1-2 of the present invention were compared and analyzed with those of Comparative Example 1. The results are shown in Table 2.

[0065] Table 2 Comparison of technical indicators between Examples 1-2 and Comparative Example 1

[0066] As can be seen from the technical indicators in Table 2: 1. Pyrrhotite removal efficiency: The magnetic concentrate yields of Examples 1 and 2 of this invention reached 11.9% and 12.2% respectively, which is about 90% higher than the 6.3% of the comparative example (nearly doubled), indicating that the pyrrhotite removal efficiency of this invention is significantly improved; 2. Control of valuable metal loss: The tin grade of the magnetic concentrate in Examples 1 and 2 of this invention is 0.21% and 0.17% respectively, which is 40%-51% lower than that of the comparative example of 0.35%, proving that this invention can effectively control the loss of valuable metals; 3. Product quality: The sulfur grade of the magnetite concentrate obtained by this invention reaches 46.8%-47.2%, which is 3.2-3.6 percentage points higher than that of the comparative example of 43.6%, and the product quality is significantly improved; 4. Process adaptability: Example 2, by optimizing the magnetic separation field strength ratio, further reduced the loss of valuable metals while maintaining a high pyrrhotite removal rate, demonstrating the adaptability and optimizability of the process of the present invention to ores with different properties.

[0067] Based on the above embodiments and experimental data, the "pre-removal method of magnetite in polymetallic sulfide ores" provided by the present invention shows significant technological progress and comprehensive advantages compared with the prior art (traditional single magnetic separation process).

[0068] Experimental results show that the synergistic process of "one-stage medium-magnetic separation tailings removal—rough concentrate regrinding—two-stage high-gradient magnetic separation fine cleaning" described in this invention can stably increase the total magnetic concentrate yield to 11.9%, while effectively controlling the content of valuable metals such as tin in the final pyrrhotite concentrate to below 0.22%. Compared with traditional single magnetic separation processes, this invention successfully reduces the loss rate of valuable metals such as tin in magnetic products by 40% to 51% while nearly doubling the removal efficiency of pyrrhotite. This achievement is mainly attributed to the precise matching of gradient magnetic field strength with mineral crystal properties and liberation behavior, as well as the efficient liberation effect of staged grinding on intergrowths.

[0069] In summary, this invention, through innovative process design and optimized combination of key operating parameters, successfully resolves the inherent contradiction between "efficient removal of pyrrhotite" and "effective protection of valuable metals" in the beneficiation of complex polymetallic sulfide ores. This process not only significantly improves the removal efficiency and product quality of pyrrhotite but also minimizes the loss of valuable metals, exhibiting advanced overall technical indicators and a stable and reliable process. Furthermore, due to its clear principle and wide applicability, this invention provides a technical solution with significant promotional value for the clean, efficient, and comprehensive utilization of similar complex mineral resources.

[0070] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical principles disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for pre-removal of pyrrhotite from polymetallic sulfide ores, characterized in that, Includes the following steps: Step S1, Primary grinding and classification of raw ore: The polymetallic sulfide ore is subjected to primary grinding, and the grinding product is classified to obtain a classification overflow of a specified fineness; Step S2, First-stage magnetic separation and tailings disposal: The graded overflow is subjected to first-stage magnetic separation to obtain first-stage magnetic concentrate and first-stage magnetic tailings; Step S3, regrinding of the first-stage magnetic concentrate and further fine separation of the second-stage magnetic concentrate: The first-stage magnetic concentrate is regrinded and then subjected to second-stage magnetic separation to obtain second-stage magnetic concentrate and second-stage magnetic tailings.

2. The method for pre-removal of magnetite from polymetallic sulfide ores according to claim 1, characterized in that, The magnetic field strength of the first-stage magnetic separation in step S2 is lower than that of the second-stage magnetic separation in step S3. The first-stage magnetic separation in step S2 is a medium magnetic field separation, and the second-stage magnetic separation in step S3 is a strong magnetic field separation.

3. The method for pre-removal of pyrrhotite from polymetallic sulfide ores according to claim 1, characterized in that, Includes at least one of the following technical features: (1) The fineness of the graded overflow in step S1 is -0.074 mm particle size, with a content of 75% to 85%; (2) In step S1, lime is added as a modifier during the grinding process. The amount of lime used is 2 kg / t to 4 kg / t based on the mass of the raw ore.

4. The method for pre-removal of magnetite from polymetallic sulfide ores according to claim 2, characterized in that, Includes at least one of the following technical features: (1) The magnetic field strength of the magnetic separation section mentioned in step S2 is 0.4T~0.7T; (2) The magnetic field strength of the two-stage magnetic separation in step S3 is 0.8T~1.2T.

5. The method for pre-removal of magnetite from polymetallic sulfide ores according to claim 2, characterized in that, Includes at least one of the following technical features: (1) The magnetic field strength of the magnetic separation section mentioned in step S2 is 0.5T~0.6T; (2) The magnetic field strength of the two-stage magnetic separation in step S3 is 1.0T~1.2T.

6. The method for pre-removal of magnetite from polymetallic sulfide ores according to claim 1, characterized in that, In step S3, the regrinding operation controls the fineness of the regrinded product to be such that the content of particles with a particle size of -0.043mm accounts for 80% to 90%.

7. The method for pre-removal of magnetite from polymetallic sulfide ores according to claim 1, characterized in that, Includes at least one of the following technical features: (1) The magnetic separation tailings mentioned in step S2 enter the subsequent flotation operation; (2) The tailings from the two-stage magnetic separation in step S3 are returned to the grading operation in step S1 or the feed for the first-stage magnetic separation in step S2.

8. The method for pre-removal of magnetite from polymetallic sulfide ores according to any one of claims 1 to 7, characterized in that, In step S1, the polymetallic sulfide ore is either gold-tin-copper-lead-zinc polymetallic sulfide ore or tin-lead-zinc polymetallic sulfide ore. In the gold-tin-copper-lead-zinc polymetallic sulfide ore, the gold content is 0.6 g / t ~ 0.8 g / t, the tin content is 1.00% ~ 1.30%, the copper content is 1.80% ~ 2.10%, the lead content is 2.70% ~ 3.10%, the zinc content is 8.00% ~ 9.00%, and the iron content is 16.50% ~ 17.00% by mass percentage. The pyrrhotite is mainly pyrrhotite, which contains both monoclinic and hexagonal crystal systems.

9. The method for pre-removal of magnetite from polymetallic sulfide ores according to claim 8, characterized in that, In step S2, a section of magnetic separation tailings enters the subsequent lead-zinc flotation and cassiterite gravity separation operations.

10. The method for pre-removal of magnetite from polymetallic sulfide ores according to claim 8, characterized in that, In step S1, the polymetallic sulfide ore is a gold-tin-copper-lead-zinc polymetallic sulfide ore. In step S2, the secondary magnetic separation concentrate is a high-grade magnetite concentrate, and the tin grade in the secondary magnetic separation concentrate is no higher than 0.22%.

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