Beneficiation process of lead-zinc-silver ore and its flotation reagents

Abstract

The present application relates to the technical field of mineral processing, and more particularly to a beneficiation process for lead-zinc-silver ore and a flotation reagent thereof, comprising the following steps: (1) grinding operation; (2) lead flotation operation, obtaining lead rough concentrate and lead rough tailings; (3) middling treatment operation, combining the tailings of lead cleaning and the concentrate of lead scavenging as lead middlings; (4) zinc flotation operation, obtaining zinc rough concentrate and final tailings; (5) zinc cleaning operation, obtaining zinc concentrate; (6) tail gas utilization. By optimizing the reagent formula and accurate proportioning in the lead and zinc flotation stages, a more selective depressant and collector system is constructed, the specificity and economy of reagent use are improved, and at the same time, the process realizes accurate regulation of the flotation chemical environment and resource utilization of process waste, and enhances the adaptability to the middling circulation problem.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mineral processing, and particularly relates to a beneficiation process of lead-zinc-silver ore and a flotation reagent thereof. BACKGROUND

[0002] The "lead preferential flotation-zinc subsequent separation" is a mature process route for treating lead-zinc-silver polymetallic ore, but it still faces a series of challenges in production practice. First, in order to achieve effective separation of lead and zinc, a large amount of lime and depressant (such as zinc sulfate, sodium sulfite) is usually added, resulting in high reagent cost and poor adaptability to complex ores. The phenomenon of zinc inclusions in lead concentrate or low zinc recovery rate often occurs. Second, the middlings produced in the flotation process (including the scavenging concentrate and the subsequent cleaning tailings) are usually directly returned to the roughing operation, which contains a large amount of un-dissociated intergrowth particles. The particles are recycled and accumulated in the process, which seriously interferes with the separation environment and becomes a key bottleneck for further improving the concentrate grade and recovery rate. In addition, although the tail gas rich in sulfur dioxide produced by lead-zinc smelting can be resourceized through the acid-making system, its potential application value in the upstream beneficiation link has not been explored. At the same time, the high-alkalinity wastewater produced in the beneficiation process still needs to consume additional reagents for neutralization treatment. The existing technology is relatively independent in each unit operation (smelting, beneficiation, and water treatment), and lacks a comprehensive innovative process that can utilize the upstream and downstream waste materials cooperatively and achieve optimization and cost reduction of the whole process.

[0003] CN106076604A provides a beneficiation process of lead-zinc-silver ore. The grinding fineness of the raw ore in the grinding operation is 50% to 60% of -200 mesh. The ball-milled raw ore is first subjected to lead roughing in the lead separation operation, which includes the step of adding diesel oil before the lead roughing. The raw ore after the lead separation operation is subjected to zinc roughing in the zinc separation operation, which includes the step of adding diesel oil before the zinc roughing. The present application eliminates the traditional flotation reagent pyrite depressant sodium sulfite, which not only reduces the cost of the lead-zinc-silver ore beneficiation process, but also helps to improve the recovery rate of lead, zinc, and silver. Moreover, it avoids the serious channeling phenomenon in the flotation process when the lead-zinc-silver ore is highly oxidized, and diesel oil has strong collecting ability for sphalerite. However, it does not solve the aforementioned problems. SUMMARY

[0004] In order to make up for the above shortcomings, the present application provides a beneficiation process of lead-zinc-silver ore and a flotation reagent thereof. By optimizing the reagent formula and accurate proportioning in the lead and zinc flotation stages, a more selective depressant and collector system is constructed, the specificity and economy of reagent use are improved, the accurate regulation of the flotation chemical environment and the resourceization of process waste are realized in the process, the adaptability to the middlings recycling problem is enhanced, and the operation stability and resource efficiency of the whole system are improved.

[0005] In order to achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0006] A beneficiation process of lead-zinc-silver ore, comprising the following steps:

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

[0008] (2) Lead flotation operation: performing lead roughing on the ore slurry obtained in step (1) to obtain lead rough concentrate and lead roughing tailings; the lead roughing is performed in an alkaline ore slurry environment created by lime, while adding zinc sulfate, sodium sulfite, sulfur nitrogen No. 9 and ammonium butyl dithiophosphate into the ore slurry; and control gas A is introduced into the flotation machine, the control gas A being a mixed gas of nitrogen and air, wherein the oxygen volume concentration is controlled at 2%-5%;

[0009] (3) middling treatment operation: performing at least one lead scavenging on the lead roughing tailings, and performing at least two lead cleaning on the lead rough concentrate; the tailings of the first lead cleaning are returned to the lead roughing operation, and the tailings of the subsequent lead cleaning and the concentrate of the lead scavenging are combined as lead middlings;

[0010] (4) Zinc flotation operation: performing zinc roughing on the lead roughing tailings obtained in step (2) to obtain zinc rough concentrate and final tailings; the zinc roughing is performed in an alkaline ore slurry environment created by lime, while adding copper sulfate and butyl xanthate into the ore slurry; and control gas B is introduced into the flotation machine, the control gas B being air or oxygen-enriched air, wherein the oxygen volume concentration is controlled at 18-23%;

[0011] (5) Zinc cleaning operation: performing at least two zinc cleaning on the zinc rough concentrate to obtain zinc concentrate;

[0012] (6) Tail gas utilization step: the tail gas rich in sulfur dioxide or carbon dioxide generated in the lead-zinc smelting process is selectively applied to the following links after purification and concentration adjustment:

[0013] a. adding the tail gas rich in sulfur dioxide into the slurry mixing barrel before the lead flotation operation, for assisting in inhibiting sphalerite and pyrite; and / or

[0014] b. introducing the tail gas rich in carbon dioxide into the beneficiation wastewater treatment system, for neutralizing the alkalinity of the wastewater.

[0015] The core technical mechanism of the present scheme is to construct a synergistic flotation chemical and physical environment system, to realize the efficient and selective separation of lead and zinc minerals by precisely controlling the chemical environment of the slurry and the composition of the gas phase. After grinding to a suitable degree of liberation (-0.074 mm accounting for 65%-85%), the process enters the key lead flotation stage. In the strong alkaline environment created by lime, the combination of zinc sulfate and sodium sulfite is introduced, which theoretically forms a hydrophilic complex film on the surface of sphalerite to effectively inhibit its floatability; while sulfur nitrogen No. 9 and ammonium black drug are used as selective collectors to cause specific adsorption on the surface of galena. In order to achieve precise inhibition, the process innovatively introduces low-oxygen control gas A (oxygen volume ratio of 2%-5%) into the lead flotation machine. This low-oxygen environment can theoretically maximize the inhibition of the electrochemical activation of pyrite and stabilize the inhibitory effect of sulfite ions, avoiding the failure of the inhibitory film on zinc and iron due to excessive oxidation. If the oxygen concentration exceeds this range, the sphalerite and part of the inhibited sphalerite may be activated and floated, resulting in a decrease in concentrate grade; on the contrary, if the oxygen concentration is too low, the hydrophobicity of galena itself may be adversely affected. This delicate gas environment is realized by a closed-loop system composed of a dynamic gas mixing device and a redox potential sensor, ensuring the stability and optimization of the process conditions.

[0016] The tailings after lead flotation enter the zinc flotation stage, and the process conditions change fundamentally. By adding copper sulfate, the copper ions can replace the zinc ions on the surface of sphalerite, converting it into a copper-zinc surface that is easy to collect. In order to promote this activation process and enhance the adsorption efficiency of the dithiophosphate collector (butyl xanthate), the process introduces oxygen-rich control gas B (oxygen volume ratio of 18%-23%). A moderate oxygen-rich environment can promote the hydrophobic reaction of the collector on the activated sphalerite surface, but if the oxygen concentration is too high, it may lead to excessive oxidation of the mineral surface or ineffective consumption of the collector, thereby reducing the recovery rate. More importantly, additional oxygen is needed, which increases the cost of production. 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 early stage of lead flotation. The dissolved SO3 2- / HSO3 - can strengthen and partially replace the inhibitory function of sodium sulfite, achieving waste treatment with waste; while using CO2 tail gas to neutralize alkaline wastewater combines the treatment of internal waste with the pH adjustment needs of the main process, reflecting the systematic optimization of the whole process.

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

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

[0019] As preferred, before returning to the grinding operation of step (1), the lead middlings first enter a separate regrinding machine for regrinding, so that the fineness is more than 85% of -0.043mm.

[0020] As preferred, in step (1), the ore includes lead middlings with a mass ratio of 3-10%, and the rest is the original ore.

[0021] The core theory of separate regrinding of lead middlings is to break down the interlocking particles rich in it by applying stronger mechanical force. This step is crucial because the mineralogical properties of the middlings have changed from the original ore, and the main body is a tightly bound mineral aggregate that cannot be effectively separated at one time. If it is directly returned to the main mill, not only is the energy consumption not economical, but it may also be trapped in an ineffective path of "recycling - selection - recycling" due to incomplete dissociation. By delivering it to a separate regrinding machine and grinding it to an extremely high fineness of more than 85% of -0.043mm, the purpose is to physically create the limiting conditions for mineral monomer dissociation, laying the foundation for subsequent return to the flotation system and efficient separation. However, this upgrading process must be coordinated with the material balance of the system, which introduces the second preferred scheme: control the proportion of lead middlings in the grinding feed to 0-10%. This proportion is a buffer mechanism from the perspective of system dynamics. When the middlings return to the system in a high-activity state after regrinding, their total amount must be constrained within a range that does not impact the chemical environment of the main flotation operation. If this proportion exceeds the upper limit, a large amount of regrinding middlings rich in residual reagents will rush in, disrupting the balance of reagent adsorption and inhibition built by the main process, especially interfering with the precise inhibition of marmatite and pyrite in the lead flotation stage under low-oxygen environment, and even possibly causing abnormal fluctuations in the demand for zinc flotation activator, ultimately destroying the separation selectivity of the entire system. Therefore, separate regrinding ensures the quality of the middlings, and proportion control manages the flow of their return. The two work together to turn the traditional problem of middlings into a benign internal cycle that can be digested by the system, thereby ensuring that the precise flotation chemical environment established in claim 1 can be continuously and stably operated efficiently as a whole.

[0022] As preferred, in step (2), the lead roughing process adds the following amounts of reagents per ton of ore:

[0023] Lime 1000-3000g;

[0024] Zinc sulfate 300-600g;

[0025] Sodium sulfite 300-600g;

[0026] Sulphide No. 9 40-80 grams;

[0027] Tall oil 8-15 grams;

[0028] Butyl ammonium black 5-15 grams.

[0029] As preferred, it is characterized in that, in step (4), the zinc roughing process, the amount of added reagent is:

[0030] Lime 1000-3000 grams;

[0031] Copper sulphate 150-300 grams;

[0032] Butyl xanthate 20-40 grams;

[0033] Tall oil 10-20 grams.

[0034] In the lead roughing stage, the primary role of lime (1000-3000 grams / ton) is to establish and maintain a high alkalinity environment for the slurry, which is a prerequisite for the synergistic effect of zinc sulphate and sodium sulphite. At the said dosage (300-600 grams / ton each), the two inhibitors can form a stable and hydrophilic complex inhibition film on the surface of sphalerite and pyrite, and lower dosage will lead to insufficient inhibition and zinc-iron minerals entering the lead concentrate, while higher dosage may non-selectively weaken the floatability of galena and cause reagent waste. On the basis of the successful establishment of this inhibition barrier, sulphide No. 9 (40-80 grams / ton) as a strong selective collector for lead minerals, cooperates with butyl ammonium black (5-15 grams / ton) which has both foaming and collecting functions, to act on the surface of galena, making it hydrophobic and floating. This lower dosage of collector is critical 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, continuous addition of lime (1000-3000 g / t) aims to maintain the alkalinity of the system, which plays an important role in neutralizing the acid effect of lead flotation residual reagents and continuously inhibiting pyrite. The fundamental change of process conditions is achieved by the addition of copper sulfate (150-300 g / t), whose Cu²⁺ ions replace the zinc ions on the surface of sphalerite, forming a thin film of easily floating copper sulfide, completing the key transition from inhibition to activation. This activation process must be moderate, as insufficient dosage will result in incomplete activation and low zinc recovery, while excessive dosage will not only be wasteful, but also may non-selectively activate pyrite, polluting the zinc concentrate. Finally, butyl xanthate (20-40 g / t) is used as a collector, and its dosage is matched with the activated sphalerite surface area in the slurry to ensure efficient recovery; however, its dosage must also be coordinated with the degree of activation, as excessive addition when activation is insufficient will worsen the subsequent operating environment, while insufficient addition after sufficient activation will not guarantee the recovery rate. These two sets of fine quantitative reagent systems, coupled with the controlled gas environment of low oxygen followed by rich oxygen in the process, support each other and together form an integral, dynamically balanced flotation chemical system, which is the theoretical guarantee for the high selectivity separation of lead, zinc and silver minerals.

[0036] As preferred, a water treatment step is also included, in which the wastewater from lead flotation and zinc flotation is collected separately, and the zinc flotation wastewater containing copper sulfate is recycled for zinc flotation operation, and the lead flotation wastewater without copper sulfate is recycled for lead flotation operation or grinding operation.

[0037] The present scheme also proposes a lead flotation combined reagent consisting of the following components in mass fraction:

[0038] Lime 1000-3000 parts;

[0039] Zinc sulfate 300-600 parts;

[0040] Sodium sulfite 300-600 parts;

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

[0042] Pinol oil 8-15 parts;

[0043] Butyl ammonium black drug 5-15 parts.

[0044] The present scheme also proposes a zinc flotation combined reagent consisting of the following components in mass fraction:

[0045] Lime 1000-3000 parts;

[0046] Copper sulfate 150-300 parts;

[0047] Butyl xanthate 20-40 parts;

[0048] Pinol oil 10-20 parts.

[0049] The beneficiation process is particularly suitable for processing low-grade and complex symbiotic lead-zinc-silver ores, and its technical advantages are particularly significant in processing lead ores with a grade of 0.5%-3%, zinc ores with a grade of 1%-5%, and associated valuable silver ores.

[0050] Compared with the prior art, the advantages of the present application are:

[0051] 1. The present application optimizes the reagent formula and precise proportioning of lead and zinc flotation stages to build a more selective inhibitor and collector system. The synergistic inhibition of zinc sulfate and sodium sulfite at a specific dosage, combined with the selective collection of lead minerals by sulfur nitrogen No. 9 and ammonium black drug, strengthens the lead-zinc separation effect in a low-oxygen environment; while the activation of copper sulfate and the collection of zinc flotation in a rich-oxygen environment are promoted, which ensures the separation efficiency while improving the specificity and economy of reagent use.

[0052] 2. In terms of process flow, the present application introduces a phased gas control mechanism, using a low-oxygen environment for lead flotation to stabilize inhibition and a rich-oxygen environment for zinc flotation to promote recovery, combined with the in-situ use of smelting tail gas and the separate use of wastewater, to achieve precise control of the flotation chemical environment and resource utilization of process waste, enhance the adaptability to middling recycling problems, and improve the operation stability and resource efficiency of the entire system. DETAILED DESCRIPTION

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

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

[0055] Example 1

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

[0057] (1) Grinding operation: grinding the ore to a fineness of 75% of -0.074mm in the pulp; the ore includes 5% of lead middlings by mass fraction, and the balance is raw ore; the lead middlings are first fed into a separate regrinder for regrinding before returning to the grinding operation of step (1), so that the fineness reaches more than 90% of -0.043mm;

[0058] (2) Lead flotation operation: the slurry obtained in step (1) is subjected to lead roughing to obtain lead rough 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 drug are added to the slurry; and a control gas A is introduced into the flotation machine, the control gas A being a mixed gas of nitrogen and air, wherein the oxygen volume concentration is controlled at 3.5%; during the lead roughing process, the dosage of the added reagents is: lime 2000g, zinc sulfate 450g, sodium sulfite 450g, sulfur nitrogen No. 9 60g, butyl ammonium black drug 10g, and pine oil 12g per ton of ore;

[0059] (3) middling treatment operation: the lead roughing tailings are subjected to at least one lead scavenging, and the lead rough concentrate is subjected to at least two lead cleaning; the tailings of the first lead cleaning are returned to the lead roughing operation, and the tailings of the subsequent lead cleaning and the concentrate of the lead scavenging are combined as lead middlings;

[0060] (4) Zinc flotation operation: the lead roughing tailings obtained in step (2) are subjected to zinc roughing to obtain zinc rough 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, the control gas B being air or oxygen-enriched air, wherein the oxygen volume concentration is controlled at 20.5%; during the zinc roughing process, the dosage of the added reagents is: lime 2000g, copper sulfate 225g, butyl xanthate 30g, and pine oil 12g per ton of ore;

[0061] (5) Zinc cleaning operation: the zinc rough concentrate is subjected to at least two zinc cleaning to obtain zinc concentrate;

[0062] (6) Tail gas utilization step: the tail gas rich in sulfur dioxide or carbon dioxide generated in the lead-zinc smelting process is purified and concentrated, and then applied to the following links: a. the tail gas rich in sulfur dioxide is purified and dissolved in water to prepare a 2.8% sulfurous acid solution, which is then added to the slurry mixing barrel before the lead flotation operation at an amount of 300g per ton of ore, for auxiliary inhibition of sphalerite and pyrite; b. the tail gas rich in carbon dioxide is introduced into the ore dressing wastewater treatment system for neutralization of the alkalinity of the wastewater.

[0063] Example 2

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

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

[0066] (2) Lead flotation operation: the slurry obtained in step (1) is subjected to lead roughing to obtain lead rough 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 drug are added to the slurry; and a control gas A is introduced into the flotation machine, the control gas A being a mixed gas of nitrogen and air, wherein the oxygen volume concentration is controlled at 2%; during the lead roughing process, the dosage of the added reagents is: 1000g of lime, 300g of zinc sulfate, 300g of sodium sulfite, 40g of sulfur nitrogen No. 9, 5g of butyl ammonium black drug, and 8g of pine oil per ton of ore;

[0067] (3) middling treatment operation: the lead roughing tailings are subjected to at least one lead scavenging, and the lead rough concentrate is subjected to at least two lead cleaning; the tailings of the first lead cleaning are returned to the lead roughing operation, and the tailings of the subsequent lead cleaning and the concentrate of the lead scavenging are combined as lead middlings which are 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 rough 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, the control gas B being air or oxygen-enriched air, wherein the oxygen volume concentration is controlled at 18%; during the zinc roughing process, the dosage of the added reagents is: 1000g of lime, 150g of copper sulfate, 20g of butyl xanthate, and 10g of pine oil per ton of ore;

[0069] (5) zinc cleaning operation: the zinc rough concentrate is subjected to at least two zinc cleaning to obtain zinc concentrate;

[0070] (6) tail gas utilization step: the tail gas rich in sulfur dioxide or carbon dioxide generated in the lead-zinc smelting process is purified and adjusted in concentration, and then applied to the following links: a. the tail gas rich in sulfur dioxide is purified and dissolved in water to prepare a 0.5% sulfurous acid solution, which is then added to the slurry mixing barrel before the lead flotation operation at an amount of 100g per ton of ore, for auxiliary inhibition of sphalerite and pyrite; b. the tail gas rich in carbon dioxide is introduced into the ore dressing wastewater treatment system for neutralization of the alkalinity of the wastewater.

[0071] Example 3

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

[0073] (1) grinding operation: grinding the ore to a slurry with a fineness of 65% passing 0.074mm; the ore includes 10% lead middlings by mass fraction, and the balance is raw ore; the lead middlings are first subjected to regrinding in a separate regrinder before returning to the grinding operation of step (1) to achieve a fineness of more than 95% passing 0.043mm;

[0074] (2) Lead flotation operation: the slurry obtained in step (1) is subjected to lead roughing to obtain lead rough 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 drug are added to the slurry; and a control gas A is introduced into the flotation machine, the control gas A is a mixed gas of nitrogen and air, and the oxygen volume concentration is controlled at 5%; during the lead roughing process, the amount of the added reagents is: 3000 grams of lime, 600 grams of zinc sulfate, 600 grams of sodium sulfite, 80 grams of sulfur nitrogen No. 9, 15 grams of butyl ammonium black drug, and 15 grams of pine oil per ton of ore;

[0075] (3) middling treatment operation: the lead roughing tailings are subjected to at least one lead scavenging, and the lead rough concentrate is subjected to at least two lead cleaning; the tailings of the first lead cleaning are returned to the lead roughing operation, and the tailings of the subsequent lead cleaning and the concentrate of the lead scavenging are combined as lead middlings;

[0076] (4) Zinc flotation operation: the lead roughing tailings obtained in step (2) are subjected to zinc roughing to obtain zinc rough 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, the control gas B is air or oxygen-enriched air, and the oxygen volume concentration is controlled at 23%; during the zinc roughing process, the amount of the added reagents is: 3000 grams of lime, 300 grams of copper sulfate, 40 grams of butyl xanthate, and 20 grams of pine oil per ton of ore;

[0077] (5) Zinc cleaning operation: the zinc rough concentrate is subjected to at least two zinc cleaning to obtain zinc concentrate;

[0078] (6) Tail gas utilization step: the tail gas rich in sulfur dioxide or carbon dioxide generated in the lead-zinc smelting process is purified and concentrated, and then applied to the following links: a. the tail gas rich in sulfur dioxide is purified and dissolved in water to prepare a 5% sulfurous acid solution, which is then added to the slurry mixing barrel before the lead flotation operation at an amount of 500 grams per ton of ore, to assist in inhibiting sphalerite and pyrite; b. the tail gas rich in carbon dioxide is introduced into the ore dressing wastewater treatment system to neutralize the alkalinity of the wastewater.

[0079] Comparative Example 1

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

[0081] Comparative Example 2

[0082] The difference from Example 1 is only that the lead middlings are not subjected to regrinding by a regrinding machine before returning to the grinding operation in step (1).

[0083] Comparative Example 3

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

[0085] Comparative Example 4

[0086] The difference from Example 1 is that the control gas B is replaced by oxygen with a volume ratio of 17%.

[0087] Comparative Example 5

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

[0089] Comparative Example 6

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

[0091] Traditional process:

[0092] (1) Grinding operation: grinding the ore to a fineness of 65% of -0.074 mm;

[0093] (2) Lead flotation operation: performing lead roughing on the slurry obtained in step (1) to obtain lead rough concentrate and lead roughing tailings; the lead roughing is performed in an alkaline slurry environment created by lime, and zinc sulfate, sodium sulfite, sulfur nitrogen No. 9, and butyl ammonium black medicine are added to the slurry; air is also introduced into the flotation machine, and the dosages of the reagents added in the lead roughing process are as follows: 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, and 8 g of butyl ammonium black medicine per ton of ore;

[0094] (3) Midling treatment operation: performing at least one lead scavenging on the lead roughing tailings and at least two lead cleaning on the lead rough concentrate; the tailings of the first lead cleaning are returned to the lead roughing operation, and the tailings of the subsequent lead cleaning and the concentrate of the lead scavenging are combined as lead middlings;

[0095] (4) Zinc flotation operation: performing zinc roughing on the lead roughing tailings obtained in step (2) to obtain zinc rough concentrate and final tailings; the zinc roughing is performed in an alkaline slurry environment created by lime, and copper sulfate and butyl xanthate are added to the slurry; air is also introduced into the flotation machine, and the dosages of the reagents added in the zinc roughing process are as follows: 3800 g of lime, 180 g of copper sulfate, 100 g of diesel, and 25 g of butyl xanthate per ton of ore;

[0096] (5) Zinc cleaning operation: performing at least two zinc cleaning on the zinc rough concentrate 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 of a lead-zinc-silver ore, characterized in that, The method comprises the following steps: (1) grinding operation: grinding the ore to a fineness of -0.074mm accounting for 65%-85% of the ore slurry; (2) lead flotation operation: the ore slurry obtained in step (1) is subjected to lead roughing to obtain lead rough concentrate and lead roughing tailings; the lead roughing is carried out in an alkaline ore slurry environment created by lime, and zinc sulfate, sodium sulfite, sulfur nitrogen No. 9 and butyl ammonium black drug are added to the ore slurry; and a control gas A is introduced into the flotation machine, the control gas A being a mixed gas of nitrogen and air, wherein the oxygen volume concentration is controlled at 2%-5%; (3) middling treatment operation: the lead roughing tailings are subjected to at least one lead scavenging, and the lead rough concentrate is subjected to at least two lead cleaning; the tailings of the first lead cleaning are returned to the lead roughing operation, and the tailings of the subsequent lead cleaning and the concentrate of the lead scavenging are combined as lead middlings; (4) zinc flotation operation: the lead scavenging tailings obtained in step (3) are subjected to zinc roughing to obtain zinc rough concentrate and final tailings; the zinc roughing is carried out in an alkaline ore slurry environment created by lime, and copper sulfate and butyl xanthate are added to the ore slurry; and a control gas B is introduced into the flotation machine, the control gas B being air or oxygen-enriched air, wherein the oxygen volume concentration is controlled at 18-23%; (5) zinc cleaning operation: the zinc rough concentrate is subjected to at least two zinc cleaning to obtain zinc concentrate; (6) tail gas utilization step: the tail gas rich in sulfur dioxide or carbon dioxide generated in the lead-zinc smelting process is applied to the following links after purification and concentration adjustment: a. the tail gas rich in sulfur dioxide is added to the lead flotation operation to assist in inhibiting sphalerite and pyrite; and / or b. the tail gas rich in carbon dioxide is introduced into the beneficiation wastewater treatment system to neutralize the alkalinity of the wastewater.

2. The beneficiation process of a lead-zinc-silver ore as claimed in claim 1, wherein, In step (6) a, the tail gas rich in sulfur dioxide is purified, dissolved in water to form a sulfurous acid solution with a concentration of 0.5%-5%, and then added to the lead flotation operation in an amount of 100-500 grams of sulfurous acid solution per ton of ore.

3. The beneficiation process of a lead-zinc-silver ore as claimed in claim 1, wherein, In step (3), the lead middlings are returned to the lead roughing operation of step (2) or returned to the grinding operation of step (1).

4. The beneficiation process of a lead-zinc-silver ore as claimed in claim 3, wherein, The lead middlings are first introduced into a separate regrinder for regrinding before returning to the grinding operation of step (1), so that the fineness reaches more than 85% of -0.043mm.

5. The beneficiation process of a lead-zinc-silver ore as claimed in claim 1, wherein, In step (1), the ore includes lead middlings with a mass fraction of 3-10%, and the balance is the original ore.

6. The beneficiation process of a lead-zinc-silver ore as claimed in claim 1, wherein, In step (2), the amount of added reagents for each ton of ore in the lead roughing process is: lime 1000-3000 grams; zinc sulfate 300-600 grams; sodium sulfite 300-600 grams; sulfur nitrogen No. 9 40-80 grams; pine oil 8-15 grams; butyl ammonium black drug 5-15 grams.

7. The beneficiation process of a lead-zinc-silver ore as claimed in claim 1, wherein, In step (4), the amount of added reagents for each ton of ore in the zinc roughing process is: lime 1000-3000 grams; copper sulfate 150-300 grams; butyl xanthate 20-40 grams; pine oil 10-20 grams.

8. The beneficiation process of a lead-zinc-silver ore as claimed in claim 1, wherein, Also included is a water treatment step in which the effluents from lead flotation and zinc flotation are collected separately, and the zinc flotation effluent containing copper sulfate is recycled to the zinc flotation operation, and the lead flotation effluent, which does not contain copper sulfate, is recycled to the lead flotation operation or to the grinding operation.

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