Beneficiation process of lead-zinc-silver ore and flotation reagent thereof

Abstract

The invention relates to the technical field of beneficiation, in particular to a beneficiation process of lead-zinc-silver ore and a flotation reagent of the beneficiation process of the lead-zinc-silver ore. (2) lead flotation operation is conducted, and lead rough concentrate and lead roughing tailings are obtained; (3) middling treatment operation is conducted, specifically, tailings obtained after lead concentration and concentrates obtained after lead scavenging are combined into lead middlings; (4) zinc flotation operation is conducted, and zinc rough concentrate and final tailings are obtained; (5) carrying out zinc concentration operation to obtain zinc concentrate; and (6) tail gas utilization. According to the method, the inhibitor and collecting agent system with higher selectivity is constructed by optimizing the reagent formula and the accurate proportion in the lead and zinc flotation stage, the pertinence and economical efficiency of reagent use are improved, meanwhile, accurate regulation and control of the flotation chemical environment and recycling of waste in the process are achieved technologically, and the adaptability to the middling circulation problem is enhanced.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, and in particular to a mineral processing technology for lead-zinc-silver ore and its flotation reagents. Background Technology

[0002] The "preferential lead flotation followed by zinc separation" process is a mature technology for processing lead-zinc-silver polymetallic ores; however, it still faces a series of challenges in production practice. First, to achieve effective lead-zinc separation, large amounts of lime and inhibitors (such as zinc sulfate and sodium sulfite) are typically added, resulting in high reagent costs and poor adaptability to complex ores. Zinc inclusions or low zinc recovery rates are common in lead concentrates. Second, the middlings generated during flotation (including scavenging concentrate and subsequent cleaning tailings) are usually directly returned to the roughing operation. These middlings contain a large number of incompletely liberated intergrowth particles, which accumulate in the process, severely interfering with the separation environment and becoming a key bottleneck restricting further improvements in concentrate grade and recovery. Furthermore, although the sulfur dioxide-rich tail gas generated from lead-zinc smelting can be recycled through an acid production system, its potential application value in upstream beneficiation has not been explored. Simultaneously, the highly alkaline wastewater generated during beneficiation still requires additional reagents for neutralization. In existing technologies, each unit operation (smelting, mineral processing, and water treatment) is relatively independent, and there is a lack of a comprehensive and innovative process that can coordinate the utilization of upstream and downstream wastes and achieve full-process optimization, cost reduction, and efficiency improvement.

[0003] CN106076604A discloses a beneficiation process for lead-zinc-silver ore. In the grinding operation, the raw ore is ground to a fineness of -200 mesh (50%–60%). The ball-milled ore is then subjected to lead roughing in lead beneficiation, which includes the addition of diesel fuel before the roughing process. The ore after lead beneficiation is then subjected to zinc roughing in zinc beneficiation, also including the addition of diesel fuel before the zinc roughing process. This invention eliminates sodium sulfite, a pyrite inhibitor used in traditional flotation reagents, thus reducing the cost of lead-zinc-silver ore beneficiation and improving the recovery rates of lead, zinc, and silver. Furthermore, it avoids the severe runoff phenomenon that occurs during flotation when the lead-zinc-silver ore has a high degree of oxidation, and diesel fuel has a strong collecting ability for sphalerite. However, it does not solve the aforementioned problems. Summary of the Invention

[0004] To overcome the above deficiencies, this invention provides a beneficiation process for lead-zinc-silver ore and its flotation reagents. By optimizing the reagent formulation and precise ratio in the lead and zinc flotation stages, a more selective inhibitor and collector system is constructed, improving the targeting and economy of reagent use. At the same time, the process achieves precise control of the flotation chemical environment and resource utilization of process waste, enhancing adaptability to middlings recycling issues and improving the operational stability and resource efficiency of the entire system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A beneficiation process for lead-zinc-silver ore includes the following steps:

[0007] (1) Grinding operation: Grind the ore into a slurry with a fineness of -0.074mm accounting for 65%-85%;

[0008] (2) Lead flotation operation: The slurry obtained in step (1) is subjected to lead roughing to obtain lead concentrate and lead roughing tailings; the lead roughing is carried out in an alkaline slurry environment created by lime, and zinc sulfate, sodium sulfite, sulfur nitrogen No. 9 and butyl ammonium black powder are added to the slurry; and control gas A is introduced into the flotation machine. Control gas A is a mixture of nitrogen and air, wherein the oxygen volume concentration is controlled at 2%-5%;

[0009] (3) Mid-mineral processing: The lead roughing tailings are subjected to lead scavenging at least once, and the lead concentrate is subjected to lead cleaning at least twice; the tailings from the first lead cleaning are returned to the lead roughing operation, and the tailings from subsequent lead cleaning and the concentrate from lead scavenging are combined into mid-minerals.

[0010] (4) Zinc flotation operation: The lead roughing tailings obtained in step (2) are subjected to zinc roughing to obtain zinc concentrate and final tailings; the zinc roughing is carried out in an alkaline slurry environment created by lime, and copper sulfate and butyl xanthate are added to the slurry; and a control gas B is introduced into the flotation machine, which is air or oxygen-enriched air, wherein the oxygen volume concentration is controlled at 18-23%;

[0011] (5) Zinc refining operation: The zinc crude concentrate is subjected to at least two zinc refining operations to obtain zinc concentrate;

[0012] (6) Waste gas utilization steps: The waste gas rich in sulfur dioxide or carbon dioxide generated during lead and zinc smelting is purified and its concentration adjusted, and then selectively applied to the following stages:

[0013] a. Adding sulfur dioxide-rich tail gas to the pre-flotation mixing tank before lead flotation to help suppress sphalerite and pyrite; and / or

[0014] b. The carbon dioxide-rich tail gas is introduced into the mineral processing wastewater treatment system to neutralize the alkalinity of the wastewater.

[0015] The core technical mechanism of this scheme lies in constructing a synergistic flotation chemical and physical environment system. By precisely controlling the chemical environment and gas phase composition of the pulp, highly efficient and selective separation of lead and zinc minerals is achieved. After grinding reaches a suitable degree of liberation (65%-85% of particles are -0.074mm), the process enters the critical lead flotation stage. In this stage, in the strongly alkaline environment created by lime, the combination of zinc sulfate and sodium sulfite is introduced. Theoretically, this combination forms a hydrophilic complex film on the surface of sphalerite, effectively inhibiting its floatability. Meanwhile, sulfur-nitrogen No. 9 and butyl ammonium black dye act as selective collectors, undergoing specific adsorption on the surface of galena. To achieve precise inhibition, the process innovatively introduces a low-oxygen control gas A (oxygen volume percentage of 2%-5%) into the lead flotation machine. This low-oxygen environment can theoretically maximize the inhibition of electrochemical activation of pyrite and stabilize the inhibitory effect of sulfite ions, preventing the inhibition film on zinc and iron from failing due to excessive oxidation. If the oxygen concentration exceeds this range, pyrite and some of the suppressed sphalerite may be activated and float to the surface, leading to a decrease in concentrate grade; conversely, if the oxygen concentration is too low, the hydrophobicity of galena itself may also be adversely affected. This precise gas environment is achieved by a closed-loop system consisting of a dynamic gas mixing device and a redox potential sensor, ensuring the stability and optimization of process conditions.

[0016] The tailings from lead flotation enter the zinc flotation stage, where the process conditions undergo a fundamental change. By adding copper sulfate, its copper ions can displace zinc ions on the surface of sphalerite, transforming it into a copper-zinc surface that is easier to collect. To promote this activation process and enhance the adsorption efficiency of xanthate collectors (butyl xanthate), an oxygen-enriched controlled gas B (oxygen volume percentage 18%-23%) is introduced into the process. A moderately oxygen-enriched environment promotes the hydrophobication reaction of the collector on the activated sphalerite surface; however, if the oxygen concentration is too high, it may lead to excessive oxidation of the mineral surface or ineffective consumption of the collector, thus reducing the recovery rate. More importantly, it requires additional oxygen supplementation, which increases production costs. Finally, the synergy of the process is also reflected in the closed-loop utilization of the tail gas: the sulfur dioxide-rich tail gas generated from upstream smelting is introduced into the lead flotation front section, where the dissolved SO3... 2- / HSO3 - It can enhance and partially replace the inhibitory function of sodium sulfite, realizing the treatment of waste with waste; while using CO2 tail gas to neutralize alkaline wastewater combines the treatment of internal waste materials with the pH control requirements of the main process, reflecting the systematic optimization of the entire process.

[0017] As a preferred option, in step (6)a, the tail gas rich in sulfur dioxide is purified and dissolved in water to make a sulfurous acid solution with a concentration of 0.5%-5%, and then 100-500 grams of sulfurous acid solution are added per ton of ore to the lead flotation operation.

[0018] Preferably, in step (3), the lead middlings can be selectively returned to the lead roughing operation in step (2) or returned to the grinding operation in step (1).

[0019] Preferably, the lead middlings ore is first regrinded in a separate regrinding mill before returning to the grinding operation in step (1) so that its fineness reaches more than 85% -0.043mm.

[0020] Preferably, in step (1), the ore includes lead middlings with a mass ratio of 3-10%, and the remainder is raw ore.

[0021] The core theory behind separate regrinding of lead middlings lies in applying stronger mechanical force to directionally break down the abundant intergrowth particles within it. This step is crucial because the mineralogical characteristics of middlings differ from those of the ore; its main component is tightly bound mineral aggregates that failed to be effectively separated in a single pass. Returning it directly to the main mill is not only energy-inefficient but may also lead to an ineffective "recycle-cleaning-recycle" cycle due to incomplete liberation. By feeding it to a separate regrinding mill and grinding it to an extremely high fineness of over 85% (-0.043mm), the aim is to physically create the extreme conditions for the liberation of mineral monomers, laying the foundation for its subsequent return to the flotation system and achieving efficient separation. However, this upgrading process must be coordinated with the system's material flow balance, which introduces a second optimal solution: controlling the proportion of lead middlings in the grinding feed to 0-10%. This proportion is a buffer mechanism from a system kinetics perspective. When the middlings are returned to the system in a highly active state after regrinding, their total amount must be constrained within a range that will not impact the chemical environment of the main flotation operation. If this ratio gets out of control and exceeds the upper limit, a large influx of regrinding middlings rich in residual reagents will disrupt the reagent adsorption and inhibition balance established in the main process. In particular, it will interfere with the precise inhibition of sphalerite and pyrite under the low-oxygen environment in the lead flotation stage, and may even cause abnormal fluctuations in the demand for oxygen-enriched zinc flotation activators, ultimately destroying the separation selectivity of the entire system. Therefore, separate regrinding ensures the quality of middlings, while ratio control manages its return flow. The synergistic effect of the two transforms the traditional problem of middlings into a virtuous internal cycle that can be digested by the system, thereby ensuring the continuous, stable, and efficient operation of the precision flotation chemical environment established in Option 1.

[0022] Preferably, in step (2), the amount of reagent added relative to each ton of ore in the lead roughing process is:

[0023] 1000-3000 grams of lime;

[0024] 300-600 grams of zinc sulfate;

[0025] 300-600 grams of sodium sulfite;

[0026] 40-80 grams of Sulfur-Nitrogen No. 9;

[0027] 8-15 grams of pine oil;

[0028] 5-15 grams of butylammonium black powder.

[0029] Preferably, in step (4), the amount of reagent added relative to each ton of ore in the zinc roughing process is:

[0030] 1000-3000 grams of lime;

[0031] 150-300 grams of copper sulfate;

[0032] 20-40 grams of Dinghuangyao;

[0033] 10-20 grams of pine oil.

[0034] In the lead roughing stage, the primary role of lime (1000-3000 g / ton) is to establish and maintain a highly alkaline slurry environment, which is a prerequisite for zinc sulfate and sodium sulfite to exert a synergistic inhibitory effect. At the above dosage (300-600 g / ton each), these two inhibitors can jointly form a stable and hydrophilic complex inhibition film on the surface of sphalerite and pyrite. Too low a dosage will lead to insufficient inhibition and zinc-iron minerals entering the lead concentrate, while too high a dosage may non-selectively weaken the floatability of galena and cause waste of reagents. Based on the successful establishment of this inhibition barrier, sulfur-nitrogen No. 9 (40-80 g / t), as a collector with strong selectivity for lead minerals, works synergistically with butylammonium black powder (5-15 g / t), which has both foaming and collecting effects, on the surface of galena, causing it to float hydrophobically. This low amount of collector is crucial and must be strictly controlled, because if it exceeds the upper limit, its strong collecting ability may partially penetrate and destroy the aforementioned inhibition film, leading to a decrease in separation selectivity.

[0035] In the subsequent zinc flotation stage, the continuous addition of lime (1000-3000 g / t) aims to maintain the alkalinity of the system. Its important role is to neutralize the acid effect caused by residual reagents from lead flotation and to continuously suppress pyrite. A fundamental shift in process conditions is achieved by the addition of copper sulfate (150-300 g / t). Its Cu²⁺ ions replace zinc ions on the surface of sphalerite, forming a floatable copper sulfide film, completing the crucial transition from suppression to activation. This activation process must be moderate; insufficient dosage results in incomplete activation and low zinc recovery, while excessive dosage is not only wasteful but may also non-selectively activate pyrite, contaminating the zinc concentrate. Finally, butyl xanthate (20-40 g / t) acts as a collector, its dosage matched to the surface area of ​​activated sphalerite in the pulp to ensure efficient recovery; however, its dosage must also be coordinated with the degree of activation. Excessive addition during insufficient activation will deteriorate the subsequent operating environment with residual xanthate, while insufficient addition after sufficient activation will compromise recovery. These two precise and quantitative reagent systems are closely coupled with the controlled gas environment of low oxygen followed by oxygen enrichment in the process, and together they constitute an inseparable, dynamically balanced flotation chemical system, which is the theoretical guarantee for achieving high selective separation of lead, zinc and silver minerals.

[0036] Preferably, the process also includes a water treatment step: wastewater generated from lead flotation and zinc flotation is collected separately, zinc flotation wastewater containing copper sulfate is recycled for zinc flotation operations, and lead flotation wastewater without copper sulfate is recycled for lead flotation operations or grinding operations.

[0037] This scheme also proposes a lead flotation reagent combination, which consists of the following components in parts by mass:

[0038] 1000-3000 parts of lime;

[0039] 300-600 parts of zinc sulfate;

[0040] 300-600 parts of sodium sulfite;

[0041] 40-80 parts of Sulfur-Nitrogen No. 9;

[0042] 8-15 parts of pine oil;

[0043] 5-15 parts of butylammonium black powder.

[0044] This scheme also proposes a zinc flotation reagent combination, which consists of the following components in parts by mass:

[0045] 1000-3000 parts of lime;

[0046] 150-300 parts of copper sulfate;

[0047] 20-40 parts of Dinghuangyao;

[0048] 10-20 parts of pine oil.

[0049] This mineral processing technology is particularly suitable for processing low- to medium-grade lead-zinc-silver ores with complex mineral symbiotic relationships. Its technological advantages are especially significant when processing difficult-to-process resources with lead grades of 0.5%-3%, zinc grades of 1%-5%, and associated valuable silver.

[0050] Compared to existing technologies, the advantages of this solution are:

[0051] 1. This scheme optimizes the reagent formulation and precise ratio in the lead and zinc flotation stages, constructing a more selective inhibitor and collector system. The synergistic inhibition of zinc sulfate and sodium sulfite at specific dosages, combined with the selective collection of lead minerals by sulfur-nitrogen No. 9 and butyl xanthate, enhances the lead-zinc separation effect under low-oxygen conditions. Meanwhile, the activation effect of copper sulfate and the collection of butyl xanthate in zinc flotation are promoted under oxygen-rich conditions. This combination ensures separation efficiency while improving the targeting and economy of reagent use.

[0052] 2. In terms of process flow, this scheme introduces a phased gas control mechanism, using a low-oxygen environment for lead flotation to stabilize and suppress it, and an oxygen-rich environment for zinc flotation to promote recovery. Combined with the in-situ utilization of smelting tail gas and the graded reuse of wastewater, it achieves precise control of the flotation chemical environment and resource utilization of process waste, enhances the adaptability to middlings recycling problems, and improves the operational stability and resource efficiency of the entire system. Detailed Implementation

[0053] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

[0054] The raw ore used in the following examples, comparative examples, and conventional schemes contained 2.8% lead, 1.4% zinc, and 70 g / t silver.

[0055] Example 1

[0056] A beneficiation process for lead-zinc-silver ore includes the following steps:

[0057] (1) Grinding operation: Grind the ore to a fineness of -0.074mm accounting for 75% of the slurry; the ore includes lead middlings with a mass ratio of 5% and the remainder is the original ore; before returning to the grinding operation in step (1), the lead middlings are first put into a separate regrinding mill for regrinding to make its fineness reach -0.043mm accounting for more than 90%;

[0058] (2) Lead flotation operation: The slurry obtained in step (1) is subjected to lead roughing to obtain lead concentrate and lead roughing tailings; lead roughing is carried out in an alkaline slurry environment created by lime, and zinc sulfate, sodium sulfite, sulfur nitrogen No. 9 and butyl ammonium black are added to the slurry; and control gas A is introduced into the flotation machine. Control gas A is a mixture of nitrogen and air, in which the oxygen volume concentration is controlled at 3.5%; In the lead roughing process, the amount of reagents added relative to each ton of ore is: 2000 g of lime, 450 g of zinc sulfate, 450 g of sodium sulfite, 60 g of sulfur nitrogen No. 9, 10 g of butyl ammonium black, and 12 g of pine oil;

[0059] (3) Mid-mineral processing: The lead roughing tailings are subjected to lead scavenging at least once, and the lead concentrate is subjected to lead cleaning at least twice; the tailings from the first lead cleaning are returned to the lead roughing operation, and the tailings from subsequent lead cleaning and the concentrate from lead scavenging are combined into mid-minerals.

[0060] (4) Zinc flotation operation: The lead roughing tailings obtained in step (2) are subjected to zinc roughing to obtain zinc concentrate and final tailings; the zinc roughing is carried out in an alkaline slurry environment created by lime, and copper sulfate and butyl xanthate are added to the slurry at the same time; and a control gas B is introduced into the flotation machine, which is air or oxygen-enriched air, wherein the oxygen volume concentration is controlled at 20.5%; the amount of reagents added relative to each ton of ore in the zinc roughing process is: 2000 grams of lime, 225 grams of copper sulfate, 30 grams of butyl xanthate, and 12 grams of pine oil;

[0061] (5) Zinc refining operation: The zinc crude concentrate is subjected to at least two zinc refining operations to obtain zinc concentrate;

[0062] (6) Tail gas utilization steps: The tail gas rich in sulfur dioxide or carbon dioxide generated during lead and zinc smelting is purified and its concentration adjusted, and then applied to the following steps: a. After purifying the tail gas rich in sulfur dioxide, it is dissolved in water to make a 2.8% sulfurous acid solution. Then, 300 grams of sulfurous acid solution are added per ton of ore to the slurry preparation tank before lead flotation to help suppress sphalerite and pyrite; b. The tail gas rich in carbon dioxide is introduced into the mineral processing wastewater treatment system to neutralize the alkalinity of the wastewater.

[0063] Example 2

[0064] A beneficiation process for lead-zinc-silver ore includes the following steps:

[0065] (1) Grinding operation: Grind the ore to a slurry with a fineness of -0.074 mm accounting for 85%; the ore is the raw ore;

[0066] (2) Lead flotation operation: The slurry obtained in step (1) is subjected to lead roughing to obtain lead concentrate and lead roughing tailings; lead roughing is carried out in an alkaline slurry environment created by lime, and zinc sulfate, sodium sulfite, sulfur nitrogen No. 9 and butyl ammonium black are added to the slurry; and control gas A is introduced into the flotation machine. Control gas A is a mixture of nitrogen and air, in which the oxygen volume concentration is controlled at 2%; During the lead roughing process, the amount of reagents added relative to each ton of ore is: 1000 g of lime, 300 g of zinc sulfate, 300 g of sodium sulfite, 40 g of sulfur nitrogen No. 9, 5 g of butyl ammonium black, and 8 g of pine oil;

[0067] (3) Mid-mineral processing: The lead roughing tailings are subjected to lead scavenging at least once, and the lead concentrate is subjected to lead cleaning at least twice; the tailings from the first lead cleaning are returned to the lead roughing operation, and the tailings from subsequent lead cleaning and the concentrate from lead scavenging are combined into lead mid-minerals and returned to step (2).

[0068] (4) Zinc flotation operation: The lead roughing tailings obtained in step (2) are subjected to zinc roughing to obtain zinc concentrate and final tailings; the zinc roughing is carried out in an alkaline slurry environment created by lime, and copper sulfate and butyl xanthate are added to the slurry at the same time; and a control gas B is introduced into the flotation machine, which is air or oxygen-enriched air, wherein the oxygen volume concentration is controlled at 18%; the amount of reagents added relative to each ton of ore in the zinc roughing process is: 1000 grams of lime, 150 grams of copper sulfate, 20 grams of butyl xanthate, and 10 grams of pine oil;

[0069] (5) Zinc refining operation: The zinc crude concentrate is subjected to at least two zinc refining operations to obtain zinc concentrate;

[0070] (6) Tail gas utilization steps: The tail gas rich in sulfur dioxide or carbon dioxide generated during lead and zinc smelting is purified and its concentration adjusted, and then applied to the following steps: a. After purifying the tail gas rich in sulfur dioxide, it is dissolved in water to make a 0.5% sulfurous acid solution. Then, 100 grams of sulfurous acid solution is added to the slurry preparation tank before lead flotation to help suppress sphalerite and pyrite; b. The tail gas rich in carbon dioxide is introduced into the mineral processing wastewater treatment system to neutralize the alkalinity of the wastewater.

[0071] Example 3

[0072] A beneficiation process for lead-zinc-silver ore includes the following steps:

[0073] (1) Grinding operation: Grind the ore to a fineness of -0.074mm accounting for 65% of the slurry; the ore includes lead middlings with a mass ratio of 10% and the remainder is the original ore; before returning to the grinding operation in step (1), the lead middlings are first refrinsed in a separate refrinsing mill to achieve a fineness of -0.043mm accounting for more than 95%;

[0074] (2) Lead flotation operation: The slurry obtained in step (1) is subjected to lead roughing to obtain lead concentrate and lead roughing tailings; lead roughing is carried out in an alkaline slurry environment created by lime, and zinc sulfate, sodium sulfite, sulfur nitrogen No. 9 and butyl ammonium black are added to the slurry; and control gas A is introduced into the flotation machine. Control gas A is a mixture of nitrogen and air, in which the oxygen volume concentration is controlled at 5%; In the lead roughing process, the amount of reagents added relative to each ton of ore is: 3000 g of lime, 600 g of zinc sulfate, 600 g of sodium sulfite, 80 g of sulfur nitrogen No. 9, 15 g of butyl ammonium black, and 15 g of pine oil;

[0075] (3) Mid-mineral processing: The lead roughing tailings are subjected to lead scavenging at least once, and the lead concentrate is subjected to lead cleaning at least twice; the tailings from the first lead cleaning are returned to the lead roughing operation, and the tailings from subsequent lead cleaning and the concentrate from lead scavenging are combined into mid-minerals.

[0076] (4) Zinc flotation operation: The lead roughing tailings obtained in step (2) are subjected to zinc roughing to obtain zinc concentrate and final tailings; the zinc roughing is carried out in an alkaline slurry environment created by lime, and copper sulfate and butyl xanthate are added to the slurry at the same time; and a control gas B is introduced into the flotation machine, which is air or oxygen-enriched air, wherein the oxygen volume concentration is controlled at 23%; the amount of reagents added relative to each ton of ore in the zinc roughing process is: 3000 grams of lime, 300 grams of copper sulfate, 40 grams of butyl xanthate, and 20 grams of pine oil;

[0077] (5) Zinc refining operation: The zinc crude concentrate is subjected to at least two zinc refining operations to obtain zinc concentrate;

[0078] (6) Tail gas utilization steps: The tail gas rich in sulfur dioxide or carbon dioxide generated during lead and zinc smelting is purified and its concentration adjusted, and then applied to the following steps: a. After purifying the tail gas rich in sulfur dioxide, it is dissolved in water to make a 5% sulfurous acid solution. Then, 500 grams of sulfurous acid solution is added to the slurry preparation tank before lead flotation to help suppress sphalerite and pyrite; b. The tail gas rich in carbon dioxide is introduced into the mineral processing wastewater treatment system to neutralize the alkalinity of the wastewater.

[0079] Comparative Example 1

[0080] The only difference from Example 1 is that the ore includes lead middlings at a mass ratio of 11%.

[0081] Comparative Example 2

[0082] The only difference from Example 1 is that the lead-in-the-metal ore was not regrinded before returning to the grinding operation in step (1).

[0083] Comparative Example 3

[0084] The only difference from Example 1 is that the control gas A is replaced with air.

[0085] Comparative Example 4

[0086] The only difference from Example 1 is that the control gas B is replaced with oxygen, which accounts for 17% of the volume.

[0087] Comparative Example 5

[0088] The only difference from Example 1 is that, in the lead roughing process, the amount of reagents added per ton of ore is: 3100 grams of lime, 300 grams of zinc sulfate, 200 grams of sodium sulfite, 40 grams of sulfur nitrogen No. 9, and 16 grams of butyl ammonium black reagent.

[0089] Comparative Example 6

[0090] The only difference from Example 1 is that, in the zinc roughing process, the amount of reagents added per ton of ore is: 2000 grams of lime, 250 grams of copper sulfate, and 45 grams of butyl xanthate.

[0091] Traditional craftsmanship:

[0092] (1) Grinding operation: Grind the ore to a slurry with a fineness of -0.074 mm accounting for 65%;

[0093] (2) Lead flotation operation: The slurry obtained in step (1) is subjected to lead roughing to obtain lead concentrate and lead roughing tailings; lead roughing is carried out in an alkaline slurry environment created by lime, and zinc sulfate, sodium sulfite, sulfur nitrogen No. 9 and butyl ammonium black reagent are added to the slurry; and air is added to the flotation machine. During the lead roughing process, the amount of reagents added relative to each ton of ore is: 3500 g of lime, 350 g of zinc sulfate, 380 g of sodium sulfite, 50 g of sulfur nitrogen No. 9, 100 g of diesel oil, and 8 g of butyl ammonium black reagent;

[0094] (3) Mid-mineral processing: The lead roughing tailings are subjected to lead scavenging at least once, and the lead concentrate is subjected to lead cleaning at least twice; the tailings from the first lead cleaning are returned to the lead roughing operation, and the tailings from subsequent lead cleaning and the concentrate from lead scavenging are combined into mid-minerals.

[0095] (4) Zinc flotation operation: The lead roughing tailings obtained in step (2) are subjected to zinc roughing to obtain zinc concentrate and final tailings; the zinc roughing is carried out in an alkaline slurry environment created by lime, and copper sulfate and butyl xanthate are added to the slurry at the same time; and air is introduced into the flotation machine. In the zinc roughing process, the amount of reagents added relative to each ton of ore is: 3800 grams of lime, 180 grams of copper sulfate, 100 grams of diesel oil, and 25 grams of butyl xanthate;

[0096] (5) Zinc refining operation: The zinc crude concentrate is subjected to at least two zinc refining operations to obtain zinc concentrate;

[0097] The exhaust gas is used to produce sulfuric acid or sulfur products.

[0098] Table 1 shows the recovery rates of copper, zinc, and silver in the examples and comparative examples.

[0099] Table 1. Recovery rates of copper, zinc, and silver in the examples and comparative examples.

[0100]

[0101] The superiority of this invention stems from the synergistic effect of the system: the low-oxygen environment in lead flotation inhibits the electrochemical activation and sulfite oxidation of pyrite, ensuring stable inhibition of sphalerite by zinc sulfate and sodium sulfite, while sulfur-nitrogen No. 9 and butyl xanthate precisely collect galena; the moderately oxygen-rich environment in zinc flotation promotes the activation of sphalerite by copper sulfate and the collection by butyl xanthate; middlings regrinding solves the problem of intergrowths, and reasonable proportion control avoids residual reagents from disrupting the separation balance. Examples 1 and 3 have better separation performance because the middlings are regrinded and the proportions are compliant, combined with appropriate reagents and gas control; although Example 2 uses only raw ore and the middlings are directly returned to roughing, it retains the core gas control and reagent synergy, and is still superior to the traditional process and comparative examples.

[0102] Comparing the comparative examples, Comparative Example 1 had an excessive middlings ratio, with the excess middlings containing residual reagents disrupting the lead flotation inhibition environment; Comparative Example 2 had middlings that were not regrinded, resulting in the failure of intergrowths to dissociate and causing impurities to float; Comparative Example 3 had lead flotation using air instead of low-oxygen gas, leading to high-oxygen activation of impurity minerals; Comparative Example 4 had insufficient oxygen concentration in the zinc flotation gas, resulting in inadequate activation of sphalerite; Comparative Example 5 had an imbalance in lead flotation reagents, causing the inhibition or collection effects to fail; and Comparative Example 6 had excessive butyl xanthate in zinc flotation, resulting in non-selective collection of impurities. All these comparative examples deviated from the core parameters of this invention or omitted key steps, and their performance was inferior to the examples.

[0103] The environmental advantages of this implementation are undeniable, primarily due to the realization of resource recovery and closed-loop utilization of upstream and downstream waste, reducing pollution and resource consumption at the source: After purification and adjustment, the sulfur dioxide-rich tail gas from smelting can assist in suppressing sphalerite and pyrite in the lead flotation stage, partially replacing sodium sulfite and reducing the cost of inhibitor procurement and chemical reagent dosage; the carbon dioxide-rich tail gas from smelting is directly used to neutralize alkaline wastewater from mineral processing, eliminating the need for additional neutralizing agents and avoiding secondary pollution and costs associated with traditional wastewater treatment using chemical reagents; simultaneously, the process collects and recycles lead and zinc flotation wastewater separately, reusing zinc flotation wastewater containing copper sulfate for zinc flotation and lead flotation wastewater without copper sulfate for lead flotation or grinding, reducing fresh water consumption and lowering the pressure on wastewater treatment and pollutant emissions. This waste-to-waste design deeply couples smelting waste with mineral processing needs, achieving environmental optimization throughout the entire process, reducing resource waste and environmental treatment costs, aligning with the development trend of green mineral processing.

Claims

1. A beneficiation process for lead-zinc-silver ore, characterized in that, Includes the following steps: (1) Grinding operation: Grind the ore into a slurry with a fineness of -0.074mm accounting for 65%-85%; (2) Lead flotation operation: The slurry obtained in step (1) is subjected to lead roughing to obtain lead concentrate and lead roughing tailings; the lead roughing is carried out in an alkaline slurry environment created by lime, and zinc sulfate, sodium sulfite, sulfur nitrogen No. 9 and butyl ammonium black powder are added to the slurry; and control gas A is introduced into the flotation machine. Control gas A is a mixture of nitrogen and air, wherein the oxygen volume concentration is controlled at 2%-5%; (3) Mid-mineral processing: The lead roughing tailings are subjected to lead scavenging at least once, and the lead concentrate is subjected to lead cleaning at least twice; the tailings from the first lead cleaning are returned to the lead roughing operation, and the tailings from subsequent lead cleaning and the concentrate from lead scavenging are combined into mid-minerals. (4) Zinc flotation operation: The lead roughing tailings obtained in step (2) are subjected to zinc roughing to obtain zinc concentrate and final tailings; the zinc roughing is carried out in an alkaline slurry environment created by lime, and copper sulfate and butyl xanthate are added to the slurry; and a control gas B is introduced into the flotation machine, which is air or oxygen-enriched air, wherein the oxygen volume concentration is controlled at 18-23%; (5) Zinc refining operation: The zinc crude concentrate is subjected to at least two zinc refining operations to obtain zinc concentrate; (6) Waste gas utilization steps: The waste gas rich in sulfur dioxide or carbon dioxide generated during lead and zinc smelting is purified and its concentration adjusted, and then selectively applied to the following stages: a. Adding sulfur dioxide-rich tail gas to lead flotation operations to help suppress sphalerite and pyrite; and / or b. The carbon dioxide-rich tail gas is introduced into the mineral processing wastewater treatment system to neutralize the alkalinity of the wastewater.

2. The beneficiation process for lead-zinc-silver ore as described in claim 1, characterized in that, In step (6)a, the tail gas rich in sulfur dioxide is purified and dissolved in water to make a sulfurous acid solution with a concentration of 0.5%-5%. Then, 100-500 grams of sulfurous acid solution are added per ton of ore to the lead flotation operation.

3. The beneficiation process for lead-zinc-silver ore as described in claim 1, characterized in that, In step (3), the lead middlings may be selectively returned to the lead roughing operation in step (2) or returned to the grinding operation in step (1).

4. The beneficiation process for lead-zinc-silver ore as described in claim 3, characterized in that, Before returning to the grinding operation in step (1), the lead ore is first regrinded in a separate regrinding mill to achieve a fineness of -0.043mm accounting for more than 85%.

5. The beneficiation process for lead-zinc-silver ore as described in claim 1, characterized in that, In step (1), the ore includes lead middlings with a mass ratio of 3-10%, and the remainder is raw ore.

6. The beneficiation process for lead-zinc-silver ore as described in claim 1, characterized in that, In step (2), the amount of reagent added per ton of ore during the lead roughing process is as follows: 1000-3000 grams of lime; 300-600 grams of zinc sulfate; 300-600 grams of sodium sulfite; 40-80 grams of Sulfur-Nitrogen No. 9; 8-15 grams of pine oil; 5-15 grams of butylammonium black powder.

7. The beneficiation process for lead-zinc-silver ore as described in claim 1, characterized in that, In step (4), the amount of reagent added relative to each ton of ore in the zinc roughing process is as follows: 1000-3000 grams of lime; 150-300 grams of copper sulfate; 20-40 grams of Dinghuangyao; 10-20 grams of pine oil.

8. The beneficiation process for lead-zinc-silver ore as described in claim 1, characterized in that, It also includes water treatment steps: wastewater generated from lead flotation and zinc flotation is collected separately, zinc flotation wastewater containing copper sulfate is recycled for zinc flotation operations, and lead flotation wastewater without copper sulfate is recycled for lead flotation operations or grinding operations.

9. A lead flotation reagent combination, characterized in that, It consists of the following components in parts by mass: 1000-3000 parts of lime; 300-600 parts of zinc sulfate; 300-600 parts of sodium sulfite; 40-80 parts of Sulfur-Nitrogen No. 9; 8-15 parts of pine oil; 5-15 parts of butylammonium black powder.

10. A zinc flotation reagent combination, characterized in that, It consists of the following components in parts by mass: 1000-3000 parts of lime; 150-300 parts of copper sulfate; 20-40 parts of Dinghuangyao; 10-20 parts of pine oil.

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