A sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor for lead-zinc separation

Abstract

This invention relates to a sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor for lead-zinc separation, comprising, by weight: 1-2 parts sodium polysulfide, 3-5 parts zinc sulfate, 1-4 parts sodium metabisulfite, and 0.1-1.5 parts organic selectivity modifier; the sodium polysulfide is Na₂S. x The formula is: x = integers from 2 to 4; the organic selective regulator is one of L-cysteine, tannin, and modified corn starch; sodium polysulfide is the core zinc-inhibiting component; zinc sulfate and sodium polysulfide work synergistically to enhance the inhibition effect on sphalerite; and the organic selective regulator further strengthens the selectivity of "inhibiting zinc but not lead," reducing lead mineral loss. This invention's composite inhibition does not require operation under strongly alkaline conditions; only neutral slurry is needed to achieve efficient inhibition, significantly reducing the amount of lime used and avoiding the problem of excessively high alkalinity in the return water. This reduces the neutralization cost of return water treatment and fundamentally solves the problem of scaling and clogging in return water and slurry pipelines.

Description

Technical Field

[0001] This invention relates to the field of mineral processing engineering technology, specifically to a sodium polysulfide-based cyanide-free zinc inhibitor for lead-zinc separation. Background Technology

[0002] In the flotation separation of lead-zinc sulfide ores, sphalerite is easily activated by metal ions such as copper ions, leading to excessive zinc content in the lead concentrate and poor lead-zinc separation. Traditional cyanide inhibitors are highly toxic and their use is strictly limited; conventional combinations of zinc sulfate and sulfite are mostly used under alkaline conditions, which are insufficient to inhibit activated sphalerite; sodium polysulfide alone has high zinc inhibition strength, but poor selectivity and poor stability in traditional processes.

[0003] Traditional lead-zinc flotation agents require zinc sulfate and lime, which makes the reagents relatively expensive. Furthermore, adding large amounts of lime leads to a high pH value in the tailings dam's return water, resulting in a poor surrounding environment. In addition, the high calcium ion content in the return water causes scaling in the return water and slurry pipes, leading to blockages, disrupting normal production, and reducing efficiency. During production, lime often splashes onto the site, resulting in poor sanitation. Therefore, sulfuric acid is needed to neutralize the water during return water treatment to achieve a neutral pH before reuse.

[0004] A search revealed that application number 202510029318.0 discloses a high-efficiency flotation process, which addresses issues such as high lime usage costs, wastewater treatment costs, and the need to improve product quality in existing technologies. While this technology discloses methods for reducing lime addition, its inhibitor still relies on a traditional combination of sodium sulfide and zinc sulfate, which has limited effectiveness in inhibiting highly activated sphalerite and still results in excessively alkaline wastewater, failing to fundamentally solve the problem of pipe scaling.

[0005] Therefore, developing a composite inhibitor that is cyanide-free, low-alkali, has strong inhibition ability and good selectivity is a technical problem that urgently needs to be solved in the field of flotation separation of lead-zinc sulfide ores. Summary of the Invention

[0006] This invention addresses many shortcomings of existing technologies by disclosing a sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation. Through the synergistic compounding of sodium polysulfide, zinc sulfate, sodium metabisulfite, and organic selective modifiers, it achieves efficient inhibition of sphalerite under neutral slurry conditions without affecting the flotation recovery of lead minerals. This solves the problems of traditional cyanide being highly toxic, traditional inhibitors requiring strongly alkaline conditions, and excessive alkalinity in return water leading to pipe scaling, thus achieving efficient and clean separation of lead and zinc.

[0007] This invention relates to a sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor. Sodium polysulfide, as the core zinc-inhibiting component, preferentially acts on the active sites on the surface of sphalerite, disrupting the stable adsorption structure of activated copper ions on the sphalerite surface. Zinc sulfate synergistically interacts with sodium polysulfide to generate hydrophilic zinc hydroxide precipitate on the sphalerite surface, further enhancing the inhibitory effect on sphalerite. Sodium metabisulfite stabilizes the structure of sodium polysulfide in the slurry system, preventing premature decomposition and extending the action time of the agent. The added organic selectivity regulator further enhances the selectivity of "inhibiting zinc but not lead," reducing the probability of lead minerals being mistakenly inhibited, decreasing mineral loss in lead concentrate, and improving the overall recovery rate of lead.

[0008] The technical means adopted by the present invention to solve the above problems are as follows: A sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor for lead-zinc separation is provided, comprising, by weight: 1-2 parts sodium polysulfide, 3-5 parts zinc sulfate, 1-4 parts sodium metabisulfite, and 0.1-1.5 parts organic selectivity modifier; wherein the sodium polysulfide is Na₂S. x x = an integer from 2 to 4; the organic selectivity regulator is one of L-cysteine, tannin, and modified corn starch; the sodium polysulfide is the core zinc-inhibiting component; the zinc sulfate and sodium polysulfide work synergistically to enhance the inhibition effect on sphalerite; the organic selectivity regulator further strengthens the selectivity of "inhibiting zinc but not lead" and reduces lead mineral loss.

[0009] In the sodium polysulfide-based cyanide-free zinc inhibitor composite depressant for lead-zinc separation of the present invention, sodium polysulfide is used as the core active component. Compared with ordinary sodium sulfide, sodium polysulfide with x of 2 to 4 carries more active sulfur ions, which can more quickly replace the activated copper ions adsorbed on the surface of sphalerite, remove the copper ions from the surface of sphalerite, and eliminate the floatability of activated sphalerite. This is an effect that ordinary sodium sulfide cannot achieve. The added sodium metabisulfite, as a stabilizer, can continuously adjust the redox potential of the pulp system, prevent sodium polysulfide from being rapidly oxidized and decomposed by oxygen in the pulp, ensure that sodium polysulfide can maintain its activity for a long time in the flotation process, extend the reagent action window, and eliminate the need for multiple reagent replenishments.

[0010] Another object of the present invention is to disclose a method for preparing the above-mentioned sodium polysulfide-based cyanide-free zinc inhibitory composite for lead-zinc separation, comprising the following steps: S1. Dissolve sodium sulfide in water to prepare a solution; slowly add a calculated amount of sulfur powder while stirring; with a molar ratio of Na2S:S = 1:1~1.5, and a reaction temperature of 80℃~85℃, sodium polysulfide is prepared. S2. According to the mass ratio: organic selectivity regulator: 10% NaOH = 1: 8~10, gelatinize the organic selectivity regulator with 10% NaOH, add water to dilute to the concentration of organic selectivity regulator 1%~2%, stir until uniform and transparent, and keep warm at 50℃~60℃ for later use. S3. Dissolve zinc sulfate and sodium metabisulfite in water to prepare a mixed solution with a mass fraction of 10%~15%; slowly add the obtained mixed solution dropwise to the diluted organic selectivity regulator at a rate of 1mL / min~3mL / min, and stir at a stirring speed of 300rpm~600rpm for 20~30min at 40℃~50℃ until the system is uniformly mixed.

[0011] Furthermore, during the flotation of lead-zinc ore, a sequential flotation process is adopted that prioritizes lead flotation while suppressing zinc flotation: first, the lead-zinc ore is ground to fully liberate the lead and zinc minerals; then, the ground slurry is poured into the flotation cell and stirred; the ball milling speed of the lead-zinc ore is 90 rpm to 120 rpm.

[0012] The composite inhibitor is then added to induce physicochemical adsorption on the zinc mineral surface, making it hydrophilic. Next, a lead mineral collector is added to hydrophobize the lead mineral surface. Following this, a frother is added, and the slurry is aerated and stirred for flotation frothing. Air is introduced at a flow rate controlled between 0.10 m³ / (m²·min) and 0.40 m³ / (m²·min). The flotation frothing time is 3 to 8 minutes.

[0013] Stable and appropriately sized bubbles are formed in the slurry. After aeration and stirring, the hydrophobic lead minerals are adsorbed on the surface of the bubbles and float to the foam layer, where they are scraped out into other containers, while the hydrophilic zinc minerals remain in the slurry, thus achieving efficient flotation separation of lead and zinc minerals.

[0014] Furthermore, the combined inhibitor is added in the following order: first, sodium polysulfide is added and stirred at 1500 rpm to 2100 rpm for 3 to 5 minutes to ensure that it preferentially interacts with the surface of lead sulfide minerals; then, a pre-mixed mixture of zinc sulfate, sodium metabisulfite, and organic selective regulator is added and stirred at 1500 rpm to 2100 rpm for 2 to 3 minutes.

[0015] Furthermore, the lead mineral collector is one or a mixture of two or more of dialkyl dithiocarbamate, dithioalkyl carbonate, or dialkyl dithiophosphate.

[0016] Further, the raw ore is crushed, ball-milled, and classified in sequence to obtain a slurry; the slurry used is a neutral slurry with a pH of 6.5~7.5.

[0017] Furthermore, the foaming agent is at least one of MIBC, No. 2 oil, pine oil, and fatty alcohol foaming agents.

[0018] The advantages of this invention compared to the prior art are: 1. The sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation described in this invention does not require the addition of cyanide throughout the entire process, eliminating the risk of highly toxic agents during production, resulting in higher operational safety and greater environmental friendliness.

[0019] 2. The sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation described in this invention does not require operation under strongly alkaline conditions. It only requires neutral slurry to achieve efficient inhibition, which greatly reduces the amount of lime used and avoids the problem of excessive alkalinity in the return water. This reduces the neutralization cost of return water treatment and solves the problem of scaling and blockage in return water pipes and slurry pipes from the root, reducing the frequency of equipment maintenance and improving production efficiency.

[0020] 3. The sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation described in this invention inhibits the synergistic effect of each component, still exhibiting strong inhibitory ability on sphalerite with a high degree of activation. At the same time, it has excellent selectivity, higher lead mineral recovery efficiency, and lower zinc content in the obtained lead concentrate. The lead-zinc separation effect is superior to that of traditional cyanide-free inhibitors.

[0021] 4. Compared with the traditional zinc sulfate + sodium sulfite system, it can achieve efficient zinc inhibition in neutral slurry without the need for large amounts of alkali to adjust the slurry, resulting in lower cost and a more environmentally friendly system; the system is cyanide-free and non-toxic, environmentally compliant, and has good stability, making it suitable for industrial applications. Detailed Implementation

[0022] The above are merely embodiments of the present invention. The present invention is not limited to the field covered by this embodiment, and common knowledge such as specific structures and characteristics in the solution are not described in detail here. It should be noted that those skilled in the art can make several modifications and improvements without departing from the content of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

[0023] The sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor for lead-zinc separation of the present invention comprises, by weight: 1-2 parts sodium polysulfide, 3-5 parts zinc sulfate, 1-4 parts sodium metabisulfite, and 0.1-1.5 parts organic selectivity modifier; wherein the sodium polysulfide is Na2S. xx=2~4; the organic selectivity regulator is one of L-cysteine, tannin, and modified corn starch; the sodium polysulfide is the core zinc-inhibiting component; the zinc sulfate and sodium polysulfide work synergistically to enhance the inhibition effect on sphalerite; the organic selectivity regulator further strengthens the selectivity of "inhibiting zinc but not lead" and reduces lead mineral loss. Example 1

[0024] This embodiment of the sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor for lead-zinc separation comprises, by weight: 1 part sodium polysulfide, 3 parts zinc sulfate, 2 parts sodium metabisulfite, and 0.1 parts organic selectivity modifier; wherein the sodium polysulfide is Na2S. x x=2; the organic selectivity regulator is modified corn starch.

[0025] Specific preparation methods include: S1. Dissolve sodium sulfide in water to prepare a solution; slowly add the calculated amount of sulfur powder while stirring; molar ratio: Na2S x Sodium polysulfide was prepared by reacting sodium polysulfide at a ratio of 1:1 (S:S = 1:1) and a reaction temperature of 80℃. S2. By mass ratio, organic selectivity regulator: 10% NaOH = 1:8. Gelatinize the organic selectivity regulator with 10% NaOH, dilute with water to a modified corn starch concentration of 1%, stir until uniform and transparent, and keep warm at 50℃ for later use. S3. Dissolve zinc sulfate and sodium metabisulfite in water to prepare a 10% (w / w) mixed solution; pour the resulting mixed solution into the diluted organic selectivity regulator at a rate of 1 mL / min to 2 mL / min, and stir at 300 rpm for 30 min at 40 °C until the system is uniformly mixed.

[0026] The order of adding the combined inhibitors is as follows: first, add sodium polysulfide and stir at 1900 rpm for 3 minutes to ensure that it preferentially interacts with the surface of lead sulfide minerals; then add the pre-mixed mixture of zinc sulfate, sodium metabisulfite and organic selective regulator and stir at 1900 rpm for 3 minutes.

[0027] This sodium polysulfide-based cyanide-free zinc-inhibiting composite depressant is used in experiments on common lead-zinc sulfide ores, and its flotation method is as follows. During lead-zinc ore flotation, a sequential flotation process prioritizing the flotation of lead-inhibiting minerals is adopted: first, the lead-zinc ore is ground to fully liberate the lead and zinc minerals; the ground slurry is poured into the flotation cell, and stirring is started. The ball mill used for grinding the lead-zinc ore has a stirring speed of 90 rpm. Subsequently, the aforementioned composite inhibitor is added, causing it to undergo physicochemical adsorption on the surface of zinc minerals, making the zinc mineral surface hydrophilic. Then, a lead mineral collector is added, making the lead mineral surface hydrophobic. After that, a frother is added, and air is introduced into the slurry for stirring. The air is introduced at a flow rate of 0.10 m³ / (m²·min), forming a stable foam layer in the slurry. The flotation foaming begins, and the flotation foaming time is 3 minutes. The hydrophobic lead minerals are adsorbed on the surface of the bubbles and float to the foam layer, where they are scraped off to other containers, while the hydrophilic zinc minerals remain in the slurry, thus achieving efficient flotation separation of lead and zinc minerals.

[0028] Mineral sample: Common lead-zinc sulfide ore.

[0029] Process conditions: grinding fineness -0.074mm, accounting for 70%~75%, pulp pH 7.0~7.5, preferential flotation process, collector using 60g / t dithioalkyl carbonate, frother No. 2 oil added 20g / t.

[0030] The flotation test was conducted with 700g of raw ore. The reagents were added in the following order: first sodium polysulfide and compound inhibitor, then dithioalkyl carbonate and No. 2 oil. The test results are shown in Table 1. Table 1

[0031]

[0032] Table 1 shows the flotation results of a preferred embodiment of the present invention, using a compound inhibitor of "sodium polysulfide + zinc sulfate, sodium metabisulfite, and pregelatinized corn starch", with the proportions of each component within the scope of the claims. Data shows that the lead concentrate yield is 19.67%, the lead concentrate grade reaches 26.64%, and the lead recovery rate is 92.09%, indicating that this reagent system has good collecting performance for galena. Particularly noteworthy is the low zinc recovery rate in the lead concentrate, as low as 13.00%, significantly better than traditional inhibitor systems. These results demonstrate that the composite inhibitor of the present invention can achieve highly efficient and selective inhibition of sphalerite under neutral pulp conditions, while maintaining a high lead recovery rate, exhibiting excellent zinc inhibition without lead inhibition. Example 2

[0033] This embodiment of the sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor for lead-zinc separation comprises, by weight: 2 parts sodium polysulfide, 5 parts zinc sulfate, 4 parts sodium metabisulfite, and 1.5 parts organic selectivity modifier; wherein the sodium polysulfide is Na2S.x x=4; the organic selectivity regulator is L-cysteine.

[0034] Specific preparation methods include: S1. Dissolve sodium sulfide in water to prepare a solution; slowly add a calculated amount of sulfur powder while stirring; with a molar ratio of Na2S:S=1:1 and a reaction temperature of 80℃, sodium polysulfide is prepared. S2. By mass ratio, organic selectivity regulator (L-cysteine): 10% NaOH = 1:10. Gelatinize the organic selectivity regulator with 10% NaOH, dilute with water to a concentration of 2%, stir until uniform and transparent, and keep warm at 60℃ for later use. S3. Dissolve zinc sulfate and sodium metabisulfite in water to prepare a mixed solution with a mass fraction of 15%; slowly add the obtained mixed solution dropwise to the diluted organic selectivity regulator at a rate of 2~3 mL / min, and stir at 600 rpm for 20 min at 50℃ until the system is uniformly mixed.

[0035] The order of adding the combined inhibitors is as follows: first, add sodium polysulfide and stir at 1500 rpm for 5 minutes to ensure that it preferentially interacts with the surface of lead sulfide minerals; then add the pre-mixed solution of zinc sulfate, sodium metabisulfite and organic selective regulator and stir at 1500 rpm for 3 minutes.

[0036] This sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor is used in experiments on common lead-zinc sulfide ores, and its flotation method is as follows. During lead-zinc ore flotation, a sequential flotation process prioritizing the flotation of lead-inhibiting minerals is adopted: first, the lead-zinc ore is ground to fully liberate the lead and zinc minerals; the ground slurry is poured into the flotation cell, and stirring is started. The ball mill used for grinding the lead-zinc ore has a stirring speed of 120 rpm. Subsequently, the composite inhibitor is added to induce physicochemical adsorption on the surface of zinc minerals, making the zinc mineral surface hydrophilic. Then, a lead mineral collector is added to hydrophobize the surface of lead minerals. After that, a frother is added, and air is introduced into the slurry for stirring. The air is introduced at a flow rate of 0.10 m³ / (m²·min) to form a stable foam layer in the slurry. The flotation foaming process begins with a flotation foaming time of 8 min. The hydrophobic lead minerals are adsorbed on the surface of the bubbles and float to the foam layer, where they are scraped off to other containers, while the hydrophilic zinc minerals remain in the slurry, thus achieving efficient flotation separation of lead and zinc minerals.

[0037] Mineral sample: Common lead-zinc sulfide ore.

[0038] Process conditions: grinding fineness -0.074mm, accounting for 70%~75%, pulp pH 6.5~7.0, preferential flotation process, collector using dialkyl dithiocarbamate 40g / t, frother MIBC 20g / t.

[0039] The flotation test was conducted with 700g of raw ore. The reagents were added in the following order: first sodium polysulfide and compound inhibitor, then dialkyl dithiocarbamate and MIBC. The test results are shown in Table 2. Table 2

[0040]

[0041] Table 2 shows the flotation results of a preferred embodiment of the present invention, using a mixture of sodium polysulfide, zinc sulfate, sodium metabisulfite, and a compound inhibitor, with the proportions of each component within the scope of the claims. Data shows that the lead concentrate yield is 19.31%, the lead concentrate grade reaches 26.78%, and the lead recovery rate is 93.03%, indicating that this reagent system has good collecting performance for galena. Particularly noteworthy is the low zinc recovery rate in the lead concentrate, as low as 12.16%, significantly better than traditional inhibitor systems. These results demonstrate that the composite inhibitor of the present invention can achieve highly efficient and selective inhibition of sphalerite under neutral pulp conditions, while maintaining a high lead recovery rate, exhibiting excellent zinc inhibition without lead inhibition. Example 3

[0042] This embodiment of the sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor for lead-zinc separation comprises, by weight: 1.5 parts sodium polysulfide, 4 parts zinc sulfate, 3 parts sodium metabisulfite, and 0.5 parts organic selectivity modifier; wherein, the sodium polysulfide is Na2S. x x=3; the organic selectivity regulator is tannin.

[0043] Specific preparation methods include: S1. Dissolve sodium sulfide in water to prepare a solution; slowly add a calculated amount of sulfur powder while stirring; with a molar ratio of Na2S:S = 1:1.5, and a reaction temperature of 85℃, sodium polysulfide is prepared. S2. By mass ratio, organic selectivity regulator (tannin): 10% NaOH = 1:9. Gelatinize the organic selectivity regulator with 10% NaOH, dilute with water to a concentration of 1%, stir until uniform and transparent, and keep warm at 60℃ for later use. S3. Dissolve zinc sulfate and sodium metabisulfite in water to prepare a mixed solution with a mass fraction of 12%; slowly add the obtained mixed solution dropwise to the diluted organic selectivity regulator at a rate of 1.5 mL / min to 2.5 mL / min, and stir at 400 rpm for 20 min at 50 °C until the system is uniformly mixed.

[0044] The order of adding the combined inhibitors is as follows: first, add sodium polysulfide and stir at 2100 rpm for 3 minutes to ensure that it preferentially interacts with the surface of lead sulfide minerals; then add the pre-mixed solution of zinc sulfate, sodium metabisulfite and organic selective regulator and stir at 2100 rpm for 2 minutes.

[0045] This sodium polysulfide-based cyanide-free zinc-inhibiting composite inhibitor was used in experiments on ordinary lead-zinc sulfide ores, and the flotation method is as follows. During lead-zinc ore flotation, a sequential flotation process prioritizing the flotation of lead-inhibiting minerals was adopted: first, the lead-zinc ore was ground to fully liberate the lead and zinc minerals; the ground slurry was poured into the flotation cell, and stirring was started. The ball mill used for grinding the lead-zinc ore had a stirring speed of 100 rpm. Subsequently, the aforementioned composite inhibitor is added, causing it to undergo physicochemical adsorption on the surface of zinc minerals, making the zinc mineral surface hydrophilic. Next, a lead mineral collector is added, making the lead mineral surface hydrophobic. Then, a frother is added, and air is introduced into the slurry for stirring. The air is introduced at a flow rate controlled at 0.10 m³ / (m²·min), forming a stable foam layer in the slurry. The flotation foaming process begins, with a flotation foaming time of 5 min. The hydrophobic lead minerals are adsorbed on the surface of the bubbles and float to the foam layer, where they are scraped off to other containers, while the hydrophilic zinc minerals remain in the slurry, thus achieving efficient flotation separation of lead and zinc minerals.

[0046] Mineral sample: Common lead-zinc sulfide ore.

[0047] Process conditions: grinding fineness -0.074mm, accounting for 70%~75%, pulp pH 6.5~7.0, preferential flotation process, collector using 40g / t dialkyl dithiophosphate, frother 20g / t pine oil.

[0048] The flotation test was conducted with 700g of raw ore. The reagents were added in the following order: first sodium polysulfide and compound inhibitor, then dialkyl dithiophosphate and pine oil. The test results are shown in Table 3. Table 3

[0049]

[0050] Table 3 shows the flotation results of a preferred embodiment of the present invention, using a mixture of sodium polysulfide, zinc sulfate, sodium metabisulfite, and a compound inhibitor, with the proportions of each component within the scope of the claims. Data shows that the lead concentrate yield is 19.04%, the lead concentrate grade reaches 26.78%, and the lead recovery rate is 90.26%, indicating that this reagent system has good collecting performance for galena. Particularly noteworthy is the low zinc recovery rate in the lead concentrate, as low as 11.80%, significantly better than traditional inhibitor systems. These results demonstrate that the composite inhibitor of the present invention can achieve highly efficient and selective inhibition of sphalerite under neutral pulp conditions, while maintaining a high lead recovery rate, exhibiting excellent zinc inhibition without lead inhibition. Comparative Example 1

[0051] The traditional zinc sulfate + sodium sulfite system was used as the inhibitor, and other process conditions were the same as in Example 1. The zinc sulfate dosage was 4.0 kg / t. The experimental results are shown in Table 4. Table 4

[0052]

[0053] As shown in Table 4, the lead concentrate yield was 21.80%, the lead concentrate grade was 23.90%, and the lead recovery rate was 92.63%, which is basically the same as that in Table 1. However, the zinc grade in the lead concentrate was as high as 7.41%, and the zinc recovery rate reached 22.27%, both significantly higher than in Example 1. This indicates that the traditional inhibitors are insufficient in suppressing sphalerite, resulting in a large amount of zinc entering the lead concentrate and seriously affecting its quality. Comparative Example 2

[0054] The four components described in this invention were used in the following specific amounts: sodium polysulfide 0.2 kg / t, zinc sulfate 1 kg / t, sodium metabisulfite 2 kg / t, compounded with modified corn starch 2 kg / t, with a total inhibitor dosage of 5.0 kg / t. Other process conditions were the same as in Example 1. The experimental results are shown in Table 5. Table 5

[0055]

[0056] Table 5 shows that the lead concentrate yield was 19.75%, the lead concentrate grade was 25.38%, and the lead recovery rate was 90.97%. The zinc grade in the lead concentrate was 7.01%, and the zinc recovery rate was 19.31%. Compared with Table 1, although this comparative experiment also used sodium polysulfide, zinc sulfate, sodium metabisulfite, and pregelatinized corn starch, the zinc inhibition effect was significantly reduced because the proportions of each component deviated from the preferred range of this invention, and the zinc recovery rate was about 6.3 percentage points higher than that in Table 1. This indicates that when the component proportions deviate from the range defined by this invention, the synergistic inhibition effect is significantly reduced. Comparative Example 3

[0057] The experiment used a partially compounded reagent. The inhibitor consisted only of zinc sulfate, sodium metabisulfite, and modified corn starch, with the same ratio as in Comparative Document 1, and a total dosage of 3.1 kg / t. No sodium polysulfide was added, and other process conditions were the same as in Example 1. The experimental results are shown in Table 6. Table 6

[0058]

[0059] Table 6 shows the comparative experimental data using a partially compounded reagent. Due to the absence of the key component in the composite inhibitor of this invention, the lead concentrate yield was 18.25%, the lead concentrate grade was 26.38%, and the lead recovery rate was 90.47%. The zinc grade in the lead concentrate was 6.72%, and the zinc recovery rate was 16.80%. Compared with Table 1, although the lead concentrate grade was similar, the lead recovery rate decreased by approximately 1.6 percentage points, while the zinc recovery rate was still nearly 3.8 percentage points higher than in Table 1. This result demonstrates that each component of the composite inhibitor of this invention is indispensable; only through the synergistic effect of the four components can deep inhibition of sphalerite be achieved while ensuring lead recovery, further confirming the inventiveness and irreplaceability of the technical solution of this invention. Comparative Example 4

[0060] The experiment was conducted using a partially compounded reagent. The inhibitor consisted of 0.5 kg / t sodium polysulfide, 2.0 kg / t zinc sulfate, and 0.1 kg / t modified corn starch. Sodium metabisulfite was not added. Other process conditions were the same as in Example 1. The experimental results are shown in Table 7. Table 7

[0061]

[0062] Table 7 shows the comparative experimental data using partially compounded reagents. Since the complete compound system of this invention was not formed, the lead concentrate yield was 19.27%, the lead concentrate grade was 25.89%, and the lead recovery rate was 91.42%. The zinc recovery rate in the lead concentrate was 16.31%. Compared with Table 1, although the lead concentrate grade was similar, the lead recovery rate decreased by approximately 0.67 percentage points, while the zinc recovery rate was still nearly 3.31 percentage points higher than in Table 1. This result demonstrates that each component of the compound inhibitor of this invention is indispensable; only through the synergistic effect of the four components can deep inhibition of sphalerite be achieved while ensuring lead recovery, further confirming the inventiveness and irreplaceability of the technical solution of this invention.

[0063] In summary, compared with the traditional zinc sulfate + sodium sulfite system, this method can achieve efficient zinc inhibition in neutral slurry without the need for large amounts of alkali to adjust the slurry, resulting in lower costs and a more environmentally friendly approach. The system is cyanide-free and non-toxic, environmentally compliant, and has good stability, making it suitable for industrial applications.

Claims

1. A sodium polysulfide-based cyanide-free zinc inhibitor for lead-zinc separation, characterized in that, The composition, by weight, includes: 1-2 parts sodium polysulfide, 3-5 parts zinc sulfate, 1-4 parts sodium metabisulfite, and 0.1-1.5 parts organic selectivity modifier; wherein the sodium polysulfide is Na₂S. x x = an integer from 2 to 4; the organic selectivity regulator is one of L-cysteine, tannin, and modified corn starch; the sodium polysulfide is the core zinc-inhibiting component; the zinc sulfate and sodium polysulfide work synergistically to enhance the inhibition effect on sphalerite; the organic selectivity regulator further strengthens the selectivity of "inhibiting zinc but not lead" and reduces lead mineral loss.

2. The preparation method of the sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation according to claim 1, characterized in that, Includes the following steps: S1. Dissolve sodium sulfide in water to prepare a solution; slowly add a calculated amount of sulfur powder while stirring; with a molar ratio of Na2S:S = 1:1~1.5, and a reaction temperature of 80℃~85℃, sodium polysulfide is prepared. S2. By mass ratio, organic selectivity regulator: 10%NaOH = 1:8~10. Gelatinize the organic selectivity regulator with 10%NaOH, dilute with water to 1%~2% concentration of organic selectivity regulator, stir until uniform and transparent, and keep warm at 50℃~60℃ for later use. S3. Dissolve zinc sulfate and sodium metabisulfite in water to prepare a mixed solution with a mass fraction of 10%~15%; add the obtained mixed solution dropwise to the diluted organic selectivity regulator, and stir at 300rpm~600rpm for 20min~30min at 40℃~50℃ until the system is uniformly mixed.

3. The flotation method using the sodium polysulfide-based cyanide-free zinc inhibitor composite depressant for lead-zinc separation as described in claim 1, characterized in that, In lead-zinc ore flotation, a sequential flotation process is adopted, prioritizing lead flotation and suppressing zinc flotation: First, the lead-zinc ore is ground to fully liberate the lead and zinc minerals; the ground slurry is poured into the flotation cell and stirred; then, the composite inhibitor is added, causing it to undergo physicochemical adsorption on the surface of the zinc mineral, making the zinc mineral surface hydrophilic; next, a lead mineral collector is added, making the lead mineral surface hydrophobic; then, a frother is added, and the slurry is aerated and stirred, with flotation and frothing; the hydrophobic lead minerals are adsorbed on the surface of the bubbles and float to the foam layer, while the hydrophilic zinc minerals remain in the slurry, thus achieving efficient flotation separation of lead and zinc minerals.

4. The flotation method for the sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation according to claim 3, characterized in that, The ball mill used for grinding the lead-zinc ore has a stirring speed of 90 rpm to 120 rpm.

5. The flotation method for the sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation according to claim 3, characterized in that, Inflation involves filling with air, with the gas flow rate controlled between 0.10 m³ / (m²·min) and 0.40 m³ / (m²·min).

6. The flotation method for the sodium polysulfide-based cyanide-free zinc inhibitor composite depressant for lead-zinc separation according to claim 5, characterized in that, The flotation skimming time is 3 to 8 minutes.

7. The flotation method for the sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation according to claim 3, characterized in that, The combined inhibitors are added in the following order: first, sodium polysulfide is added and stirred at 1500 rpm to 2100 rpm for 3 to 5 minutes to allow it to react preferentially with the surface of lead sulfide minerals; then, a pre-mixed solution of zinc sulfate, sodium metabisulfite, and organic selective regulator is added and stirred at 1500 rpm to 2100 rpm for 2 to 3 minutes.

8. The flotation method for the sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation according to claim 7, characterized in that, The lead mineral collector is one or a mixture of two or more of dialkyl dithiocarbamate, dithioalkyl carbonate, or dialkyl dithiophosphate.

9. The flotation method for the sodium polysulfide-based cyanide-free zinc inhibitor composite depressant for lead-zinc separation according to claim 3, characterized in that, The raw ore is crushed, ball-milled, and classified sequentially to obtain a slurry; the slurry used is a neutral slurry with a pH of 6.5~7.

5.

10. The flotation method for the sodium polysulfide-based cyanide-free zinc inhibitor composite for lead-zinc separation according to claim 3, characterized in that, The foaming agent is at least one of MIBC, No. 2 oil, pine oil, and fatty alcohol foaming agents.

Images