A method for settling backwater of tailings in a low-grade complex lead-zinc ore process of first sulfur and then oxygen

Abstract

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Description

Technical Field

[0001] This invention relates to the field of mineral processing water treatment technology, and in particular to a method for settling and recycling water from tailings of a low-grade complex lead-zinc mine using a process of first sulfur and then oxygen. Background Technology

[0002] In recent years, with the continuous exploitation of lead and zinc resources, easily beneficiated high-quality sulfide lead-zinc ore resources have become increasingly scarce, while complex and difficult-to-beneficiate oxide lead-zinc ore resources have gradually become the main targets of mineral processing. Low-grade, complex, and difficult-to-process lead-zinc ores have high slime content and fine particle size of valuable minerals, making their flotation processes and reagent regimes more complex. A wider variety of flotation reagents are used, resulting in slower tailings concentration and settling rates, and more complex tailings wastewater composition, severely impacting the effectiveness of wastewater reuse.

[0003] Existing technologies are mostly designed for wastewater from sulfide ore beneficiation or beneficiation of specific minerals. They lack targeted solutions for tailings settling and reclaimed water treatment in low-grade, complex, and difficult-to-treat lead-zinc ores (especially oxygen-sulfur mixed ores). For example, Chinese patent CN109368884A discloses a method for deep treatment and reuse of wastewater from oxidized lead-zinc ore beneficiation. This patent uses a pretreatment + electrodialysis + chemical oxidation process to deeply remove silicates, COD, TDS, and heavy metal ions from the water. The treated water is reused in the beneficiation process, achieving beneficiation indicators at the same level as tap water. However, this technical solution has a long process flow, large equipment investment, and high operating costs, making it economically unfeasible for low-grade mines.

[0004] The existing technologies mentioned above do not address the sedimentation and reclaimed water treatment in the "sulfur-oxygen" stepwise flotation process for low-grade, complex lead-zinc ores. The "sulfur-oxygen" flotation process is a highly efficient separation technology for low-grade, complex, and difficult-to-process lead-zinc ores. Based on the differences in surface characteristics and floatability between sulfide and oxide minerals in the ore, this technology achieves stepwise recovery of valuable metals, significantly improving resource utilization. Its core idea is: after grinding, the slurry flows by gravity into the flotation system, preferentially selecting mixed sulfide lead-zinc concentrate. The tailings slurry is then activated and directly enters the oxide ore flotation stage without pressure filtration or concentration, producing a single zinc oxide concentrate. The entire process is divided into a sulfidation section and an oxidation section. In the sulfidation section, after slurry conditioning, suitable collectors and frothers are added to preferentially float sulfide minerals, obtaining a mixed sulfide lead-zinc concentrate, achieving integrated recovery of sulfide lead and zinc, avoiding metal intermingling losses, and creating favorable conditions for subsequent oxidation stage operations. The tailings slurry from the sulfidation stage enters the oxidation stage for flotation. For the residual lead-zinc oxide minerals in the sulfidation stage tailings, direct flotation is difficult due to their poor natural hydrophobicity; therefore, pre-sulfidation treatment is necessary. A common method is to add sulfiding agents such as sodium sulfide to form a hydrophobic sulfide film on the surface of the oxide minerals, thus enabling them to float. The sulfidated oxide minerals are then separated, producing a single, high-quality zinc oxide concentrate. However, the wastewater generated from the "sulfidation-oxygenation" process for flotation of low-grade, complex, and difficult-to-process lead-zinc ores contains large amounts of residual flotation reagents (xanthate, amine collectors, sodium sulfide, etc.), heavy metal ions (lead, zinc, etc.), and suspended solids. Directly reusing this wastewater in the oxidation or sulfidation stage flotation system will have a serious negative impact on mineral processing indicators. Therefore, it is necessary to provide a method for settling and recycling water from tailings of low-grade complex lead-zinc mines using a pre-sulfurization followed by oxidation process, so that the treated recycled water can be used in the sulfidation and oxidation stages to achieve lead-zinc grade and total recovery rate in the concentrate after flotation at the same level as the fresh water used. Summary of the Invention

[0005] In order to overcome the problems existing in the background technology, the present invention provides a method for settling and recycling water of tailings from the pre-sulfurization and post-oxidation process of low-grade complex lead-zinc mines. This method enables the treated recycled water to be used in the flotation of the sulfidation and oxidation stages to achieve lead-zinc grade and total recovery rate in the concentrate at the same level as that of fresh water.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention provides a method for settling and reclaiming water from tailings of low-grade complex lead-zinc mines using a pre-sulfurization followed by oxygenation process, specifically including the following steps: (1) Add flocculant to the tailings slurry of lead-zinc oxide ore at a rate of 40-200g per ton of tailings slurry. After the reaction is complete, separate the solid and liquid to obtain a clear liquid; the clear liquid contains Ca 2+ With Mg 2+The sum of concentrations is <150 mg / L, COD value is <150 mg / L, and suspended solids are <100 mg / L; (2) The clarified liquid is reused in the following ways: (a) part or all of the clarified liquid is mixed with fresh water at a volume ratio of 1 to 3:5 and returned to the sulfidation section as beneficiation process water for sulfide lead-zinc ore; and / or (b) the remaining part or all of the clarified liquid is directly returned to the oxidation section as beneficiation process water for oxidized lead-zinc ore.

[0007] In the above technical solution, the flocculant is polyacrylamide.

[0008] In the above technical solution, the slurry concentration of the lead-zinc ore tailings slurry is 20-25%.

[0009] In the above technical solution, the pH value of the clarified liquid is 7.5~8.0.

[0010] In the above technical solution, the water used in the beneficiation process of the lead-zinc oxide ore is grinding water for lead-zinc oxide ore and flotation washing water.

[0011] In the above technical solution, the water used in the beneficiation process of the lead-zinc sulfide ore is grinding water for lead-zinc sulfide ore and flotation washing water.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention adds flocculants to the tailings slurry of oxidized lead-zinc ore and allows the recycled water to be reused in the sulfidation and oxidation stages of the lead-zinc ore flotation through different methods. This enables the treated recycled water to achieve the same lead-zinc grade and total recovery rate as the fresh water used in the sulfidation and oxidation stages, thereby improving the utilization rate of recycled water.

[0013] 2. In this invention, the clarified liquid is mixed with fresh water at a volume ratio of 1 to 3:5 and then returned to the beneficiation process of lead-zinc sulfide ore. The accumulation of negative ions can be suppressed by diluting with fresh water, ensuring that the beneficiation indicators of lead-zinc sulfide ore are at the same level as those of fresh water. Alternatively, the clarified liquid can be directly returned to the beneficiation process of lead-zinc oxide ore, which can maximize the utilization rate of recycled water without affecting the beneficiation indicators of lead-zinc oxide ore. Detailed Implementation

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0015] Example 1 A certain mineral processing plant has a processing capacity of 1000t / d for low-grade, complex, and difficult-to-process lead-zinc ore, of which the tailings slurry concentration of oxidized lead-zinc ore is 25%.

[0016] (1) Polyacrylamide flocculant was added to the tailings slurry of lead-zinc oxide ore at a dosage of 100g of flocculant per ton of tailings slurry. The slurry was then fed into a thickener for solid-liquid separation to obtain tailings slag and clarified liquid. The pH value of the obtained clarified liquid was 7.63, and the Ca... 2+ The concentration was 102.045 mg / L, Mg 2+ The concentration was 11.292 mg / L, the COD value was 52.67 mg / L, and the suspended solids were 16 mg / L.

[0017] (2) The clarified liquid is mixed with fresh water at a volume ratio of 2:5 and returned to the sulfidation section as grinding water and flotation washing water for sulfide lead-zinc ore. The remaining clarified liquid is directly returned to the oxidation section as grinding water and flotation washing water for oxidized lead-zinc ore.

[0018] The mineral processing indicators are shown in Table 1 below.

[0019] Example 2 A certain ore dressing plant has a processing capacity of 1100 t / d for low-grade, complex, and difficult-to-process lead-zinc ore, of which the tailings slurry concentration is 20%.

[0020] (1) Polyacrylamide flocculant was added to the tailings slurry of lead-zinc oxide ore at a dosage of 40g of flocculant per ton of tailings slurry. The slurry was then fed into a thickener for solid-liquid separation to obtain tailings slag and clarified liquid. The pH value of the obtained clarified liquid was 7.78, and the Ca... 2+ The concentration was 90.841 mg / L, Mg 2+ The concentration was 12.332 mg / L, the COD value was 75.24 mg / L, and the suspended solids were 20 mg / L.

[0021] (2) The clarified liquid is mixed with fresh water at a volume ratio of 3:5 and returned to the sulfidation section as grinding water and flotation washing water for sulfide lead-zinc ore. The remaining clarified liquid is directly returned to the oxidation section as grinding water and flotation washing water for oxidized lead-zinc ore.

[0022] The mineral processing indicators are shown in Table 2 below.

[0023] Example 3 A certain ore processing plant has a processing capacity of 1000 t / d for low-grade, complex, and difficult-to-process lead-zinc ore. The tailings slurry concentration of the oxidized lead-zinc ore is 23%.

[0024] (1) Polyacrylamide flocculant was added to the tailings slurry of lead-zinc oxide ore at a dosage of 200g of flocculant per ton of tailings slurry. The slurry was then fed into a thickener for solid-liquid separation to obtain tailings slag and clarified liquid. The pH value of the obtained clarified liquid was 7.80, and the Ca... 2+ The concentration was 93.054 mg / L, Mg 2+ The concentration was 15.607 mg / L, the COD value was 90.28 mg / L, and the suspended solids were 50 mg / L.

[0025] (2) The clarified liquid is mixed with fresh water at a volume ratio of 1:5 and returned to the sulfidation section as grinding water and flotation washing water for sulfide lead-zinc ore. The remaining clarified liquid is directly returned to the oxidation section as grinding water and flotation washing water for oxidized lead-zinc ore.

[0026] The mineral processing indicators are shown in Table 3 below.

[0027] Comparative Example 1 Fresh water is used directly as grinding water and flotation washing water for lead-zinc sulfide ore and lead-zinc oxide ore.

[0028] The mineral processing indicators are shown in Table 4 below.

[0029] In summary, the mineral processing indicators of Examples 1-3 and Comparative Example 1 show that the lead and zinc grades and total recovery rates of the mixed lead-zinc sulfide concentrate and zinc oxide concentrate obtained in Examples 1-3 are at the same level as those obtained by direct flotation using fresh water in Comparative Example 1. This indicates that settling and using recycled water according to the method of the present invention has virtually no impact on the flotation of the mixed lead-zinc sulfide concentrate and zinc oxide concentrate.

[0030] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for settling and recycling tailings from a low-grade, complex lead-zinc mine using a pre-sulfurization followed by oxygenation process, characterized in that: Specifically, the following steps are included: (1) Add flocculant to the tailings slurry of lead-zinc oxide ore, the amount of which is 40~200g per ton of tailings slurry, and obtain a clear liquid after solid-liquid separation; Ca in the clarified liquid 2+ With Mg 2+ The sum of concentrations is <150 mg / L, COD value is <150 mg / L, and suspended solids are <100 mg / L; (2) The clarified liquid is reused in the following ways: (a) part or all of the clarified liquid is mixed with fresh water at a volume ratio of 1 to 3:5 and returned to the sulfidation section as beneficiation process water for sulfide lead-zinc ore; and / or (b) the remaining part or all of the clarified liquid is directly returned to the oxidation section as beneficiation process water for oxidized lead-zinc ore.

2. The method for settling and recycling tailings from a low-grade complex lead-zinc mine using a pre-sulfurization followed by oxygenation process, as described in claim 1, is characterized in that: The flocculant mentioned is polyacrylamide.

3. The method for settling and recycling tailings from a low-grade complex lead-zinc mine using a pre-sulfurization followed by oxygenation process, as described in claim 1, is characterized in that: The slurry concentration of the lead-zinc oxide tailings slurry is 20-25%.

4. The method for settling and recycling tailings from a low-grade complex lead-zinc mine using a pre-sulfurization followed by oxygenation process, as described in claim 1, is characterized in that: The pH value of the clarified solution is 7.5~8.

0.

5. The method for settling and recycling tailings from a low-grade complex lead-zinc mine using a pre-sulfurization followed by oxygenation process, as described in claim 1, is characterized in that: The water used in the beneficiation process of the lead-zinc oxide ore is grinding water and flotation washing water.

6. The method for settling and recycling tailings from a low-grade complex lead-zinc mine using a pre-sulfurization followed by oxygenation process, as described in claim 1, is characterized in that: The water used in the beneficiation process of the lead-zinc sulfide ore is grinding water and flotation washing water.

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