Process for the recovery of valuable substances from cyanide residues

Abstract

The application provides a method for recovering valuable substances from cyanide residue, which comprises the following steps: first, slurry adjustment is performed on the cyanide residue to obtain slurry, air is introduced into the slurry, and an adjusting agent is added to obtain adjusted slurry; then, acid mine water is added into the adjusted slurry to adjust the pH value, and a pretreatment agent is added at the same time, and after reaction, pretreated slurry is obtained; finally, a flotation agent is added into the pretreated slurry for flotation, and after flotation, tailing slurry and concentrate slurry are obtained, and the two are subjected to pressure filtration and dehydration treatment respectively to obtain sulfur gold concentrate, pressure filtrate and tailing slurry. Through reasonable design of the treatment process, the cyanide residue is sequentially subjected to slurry adjustment, pretreatment and flotation for valuable substance recovery, acid mine water is used for purification of the cyanide residue, the recovery efficiency of the valuable substances is improved, the amount of the pretreatment agent is reduced, and the acid mine wastewater in practice is treated, so that the green ecological development of "waste treatment with waste and waste transformation into treasure" in the industry is realized.

Description

Technical Field

[0001] This invention relates to the field of waste resource utilization technology, and in particular to a method for recovering valuable substances from cyanide slag. Background Technology

[0002] The cyanide gold extraction process has a history of over 100 years and remains dominant in current gold industrial production due to its simplicity and high gold recovery rate. The cyanide process yields almost 100% of the gold tailings. Statistics show that the national gold industry produces approximately 70 million tons of cyanide tailings annually. While the cyanide tailings still contain valuable substances such as gold, silver, copper, lead, zinc, and sulfur that can be recovered, the cyanide in the tailings inhibits the floatability of sulfide minerals, reducing recovery efficiency. Therefore, pretreatment before recovery is necessary to eliminate the inhibitory effect of cyanide and achieve efficient resource recovery.

[0003] Currently, cyanide slag is generally not pretreated and directly enters the flotation process for valuable substance recovery. For example, patent CN 103276221A discloses a method for recovering copper from copper beneficiation system liquid in cyanide gold extraction tailings. This method involves adding lime to control the pH after tailings slurry conditioning, and then adding collectors and frothers to the slurry for lead beneficiation to produce lead concentrate. Some cyanide slag recovery employs pretreatment processes, primarily acid treatment to eliminate the influence of the hydrophilic film of cyanide complexes. For example, patent CN 114308396A discloses a method for high-value utilization of sulfur, iron, and gold in cyanide tailings. This method first conditions and acidifies the cyanide tailings slurry, then adds flotation reagents, and obtains a concentrate containing sulfur, iron, and gold through the flotation process.

[0004] While acidification is beneficial for the recovery of valuable substances from tailings, its cyanide removal effect is limited and cannot fully eliminate the inhibitory effect of cyanide on sulfide minerals, thus failing to maximize the economic benefits of recovery. Furthermore, existing acidification technologies mostly use sulfuric acid, resulting in difficult-to-treat wastewater and severe environmental pollution. Simultaneously, because current cyanide slag treatment technologies do not efficiently remove toxic components from the cyanide slag, the tailings after flotation fail to meet the requirements for general industrial solid waste after hazard identification, classifying them as hazardous waste and limiting the utilization of tailings as a bulk industrial solid waste. Therefore, how to efficiently eliminate the inhibitory effect of cyanide, enhance the floatability of minerals, and ensure that the tailings after flotation meet the requirements for general industrial solid waste is currently a research hotspot in the pretreatment of valuable substances in cyanide slag for recovery.

[0005] Sulfur-rich deposits in non-ferrous metal mines contain abundant sulfide minerals. These minerals contain various heavy metals such as iron, copper, zinc, aluminum, cadmium, and arsenic. Under the influence of air, water, and microorganisms, these minerals undergo a series of physicochemical reactions, including leaching, oxidation, and hydrolysis, producing sulfuric acid and sulfates. These products further interact with metal sulfides, causing the sulfides to dissolve in water as heavy metal sulfates, resulting in yellowish-brown acidic mine water containing a large amount of heavy metal ions. Acidic mine water is mostly treated using lime neutralization, which not only consumes lime but also generates a large amount of neutralization slag, increasing environmental risks. Therefore, the treatment of acidic mine water is a crucial issue that urgently needs to be addressed for the green and economical mining of non-ferrous metal mines.

[0006] In view of this, it is necessary to design an improved method for recovering valuable substances from cyanide slag, which can efficiently recover valuable substances from cyanide slag and simultaneously achieve the synergistic purification of acidic mine water and cyanide slag, thereby promoting the high-quality development of the gold industry and solving the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide a method for recovering valuable substances from cyanide slag. By rationally designing the processing technology, the cyanide slag is sequentially subjected to slurry preparation, pretreatment, and flotation to recover valuable substances. At the same time, acidic mine water is used to purify the cyanide slag, thereby improving the recovery efficiency of valuable substances. This not only reduces the amount of pretreatment agent added and lowers costs, but also disposes of the acidic mine wastewater in practice, realizing the green and ecological development concept of "treating waste with waste and turning waste into treasure" in the industry.

[0008] To achieve the above-mentioned objective, this invention provides a method for recovering valuable substances from cyanide slag, comprising the following steps:

[0009] S1. The cyanide slag is slurried to obtain slurry, and air is introduced into the slurry and a modifier is added to obtain slurry;

[0010] S2. Add acidic mine water to the slurry as described in step S1 to adjust the pH value, and add a pretreatment agent at the same time. After the reaction is complete, a pretreated slurry is obtained; the reaction time is 1.5 to 2.0 hours.

[0011] S3. Add flotation agent to the pretreated slurry in step S2 for flotation to obtain tailings slurry and concentrate slurry after flotation. Perform pressure filtration and dewatering treatment on the concentrate slurry to obtain filtrate and cyanide gold concentrate. Perform pressure filtration and dewatering treatment on the tailings slurry after flotation to obtain filtrate and tailings after flotation.

[0012] As a further improvement of the present invention, in step S2, the acidic mine water is wastewater containing one or more of iron, manganese, copper, lead, zinc, cadmium, chromium, arsenic and nickel, and the acidic mine water adjusts the pH value of the adjusted slurry to 7.4 to 8.2.

[0013] As a further improvement of the present invention, in step S2, the pretreatment agent is a mixture of diatomaceous earth and sodium sulfite, or diatomaceous earth and sodium metabisulfite, wherein the mass ratio of diatomaceous earth to sodium sulfite or sodium metabisulfite is (0.05-0.2):1.

[0014] As a further improvement of the present invention, in step S2, the amount of the pretreatment agent added is 0.5–2.0 kg / m³. 3 When the pretreatment agent is a mixture of diatomaceous earth and sodium metabisulfite, air is simultaneously introduced into the conditioning slurry, and the volume ratio of air to the conditioning slurry is (5-10):1.

[0015] As a further improvement of the present invention, in step S1, the mass concentration of the adjusted slurry is 30% to 35%, and the volume ratio of the introduced air to the adjusted slurry is (5 to 10):1.

[0016] As a further improvement of the present invention, in step S1, the modifier includes sodium hexametaphosphate and sodium lignosulfonate in a mass ratio of 1:(0.8-1.2), and the amount of the modifier added to the slurry is 200-300 g / t.

[0017] As a further improvement of the present invention, in step S3, the flotation agent includes copper sulfate, butyl xanthate, butyl ammonium black and No. 2 oil, and the addition amounts of the aforementioned four agents in the pretreated slurry are 250-350 g / t, 100-120 g / t, 40-60 g / t, and 20-40 g / t, respectively.

[0018] As a further improvement of the present invention, in step S1, the cyanide slag includes online cyanide slag and / or stockpiled cyanide slag. The online cyanide slag can be directly input into the slurry conditioning tank for slurry conditioning. The stockpiled cyanide slag is input into the recovery tank for stirring through hydraulic recovery. After being stirred evenly, it is input into the thickener for solid-liquid separation to obtain thickened underflow and overflow water. The overflow water is returned to the recovery integrated water tank, and the thickened underflow is input into the slurry conditioning tank for slurry conditioning.

[0019] As a further improvement of the present invention, in step S3, the filter liquid obtained after the tailings slurry and concentrate slurry after flotation and dewatering is returned to step S1 and recycled as hydraulic recovery water or slurry conditioning water.

[0020] As a further improvement of the present invention, in step S3, the flotation process includes one roughing, three sweeping, and three cleaning.

[0021] The beneficial effects of this invention are:

[0022] 1. The method for recovering valuable substances from cyanide slag of the present invention, through a rationally designed processing technology, involves sequentially processing the cyanide slag through slurry preparation, pretreatment, and flotation to recover valuable substances. The pretreatment process can effectively remove the inhibitory effect of cyanide on flotation, ensuring that the recovered concentrate meets the requirements of cyanide sulfide gold concentrate products, thus achieving efficient recovery of valuable substances from cyanide slag. Furthermore, based on the green ecological development concept of "treating waste with waste and turning waste into treasure," the present invention uses acidic mine water to co-purify the cyanide slag, reducing the amount of pretreatment agent added, lowering the cost of cyanide slag recovery, and also disposing of acidic mine wastewater from industry, improving resource recovery efficiency and solving the wastewater treatment problem in non-ferrous metal mines. Moreover, the tailings after flotation meet the requirements of general industrial solid waste, greatly reducing the environmental risk of solid waste stockpiling.

[0023] 2. In the pretreatment process, this invention employs acidic mine water and a pretreatment agent to synergistically purify cyanide slag. Heavy metal ions in the acidic mine water complex with free cyanide in the slurry, transforming into metallic cyanide complexes, forming a stable form that is then removed through chemical precipitation. This reduces the inhibitory effect of liquid-phase cyanide on flotation. Simultaneously, copper ions in the acidic mine water have a catalytic effect in the cyanide removal process, while iron ions can act as a combined coagulation aid for cyanide precipitation, improving cyanide removal efficiency and achieving synergistic purification of acidic mine water and cyanide slag. Furthermore, the added pretreatment agent, sodium sulfite or sodium metabisulfite, can oxidize and reduce cyanide, causing it to hydrolyze and generate ammonia gas, allowing some cyanide to be removed in gaseous form. Diatomaceous earth can adsorb some free or precipitated cyanide, further improving the cyanide removal rate in the slurry.

[0024] 3. The method for recovering valuable substances from cyanide slag provided by this invention is simple in process, safe and reliable in operation, and uses acidic mine water to purify cyanide slag. It can efficiently recover valuable substances from cyanide slag, and simultaneously remove toxic components from cyanide slag and acidic mine water. At the same time, the tailings after flotation meet the requirements of general industrial solid waste. It has significant economic, environmental and social benefits, and provides a new approach for the comprehensive utilization of cyanide slag and acidic mine wastewater. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the process for recovering valuable substances from cyanide slag in Embodiment 1 of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0028] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0029] A method for recovering valuable substances from cyanide slag includes the following steps:

[0030] S1. The cyanide slag is slurried to obtain slurry, and air is introduced into the slurry and a modifier is added to obtain the slurry.

[0031] S2. Add acidic mine water to the slurry from step S1 to adjust the pH value, and add a pretreatment agent at the same time. After the reaction is complete, a pretreated slurry is obtained; the reaction time is 1.5 to 2.0 hours.

[0032] S3. Add flotation agent to the pretreated slurry in step S2 for flotation to obtain tailings slurry and concentrate slurry after flotation. Perform pressure filtration and dewatering treatment on the concentrate slurry to obtain filtrate and cyanide gold concentrate. Perform pressure filtration and dewatering treatment on the tailings slurry after flotation to obtain filtrate and tailings after flotation.

[0033] Specifically, in step S2, the acidic mine water is wastewater containing one or more of the following: iron, manganese, copper, lead, zinc, cadmium, chromium, arsenic, and nickel. Heavy metal ions (such as iron, copper, and zinc ions) in the acidic mine water complex with free cyanide in the slurry, forming metal cyanide complexes in a stable form. These complexes are then removed through chemical precipitation, reducing the inhibitory effect of liquid-phase cyanide on flotation. Simultaneously, copper ions in the acidic mine water act as a catalyst in the cyanide removal process, while iron ions can jointly aid in coagulation and precipitation of cyanide, improving cyanide removal efficiency and achieving synergistic purification of the acidic mine water and cyanide residue. The pH of the slurry is adjusted to 7.4–8.2 using the acidic mine water; within this pH range, the pretreatment agent is more effective in removing cyanide.

[0034] In addition, the use of acidic mine water to co-purify cyanide slag not only reduces the amount of pretreatment agent added and lowers the cost of cyanide slag recycling, but also disposes of acidic mine wastewater in industry, improves the recycling rate of resources, and solves the wastewater treatment problem in non-ferrous metal mines.

[0035] In step S2, the pretreatment agent is a mixture of diatomaceous earth and sodium sulfite, or a mixture of diatomaceous earth and sodium metabisulfite, wherein the mass ratio of diatomaceous earth to sodium sulfite or sodium metabisulfite is (0.05–0.2):1. The added pretreatment agent, sodium sulfite or sodium metabisulfite, can oxidize and reduce cyanide to obtain cyanate. After hydrolysis, cyanate generates ammonia gas, thus removing some cyanide in gaseous form. Diatomaceous earth can adsorb some free or precipitated cyanide, playing a role in fixing cyanide and further improving the removal rate of cyanide in the slurry.

[0036] The amount of pretreatment agent added is 0.5–2.0 kg / m³. 3 That is, 0.5 to 2.0 kg of pretreatment agent is added per square meter of slurry; when the pretreatment agent is a mixture of diatomaceous earth and sodium metabisulfite, air is simultaneously introduced into the slurry, and the volume ratio of air to slurry is (5 to 10):1.

[0037] Specifically, in step S1, the mass concentration of the slurry is adjusted to 30%–35%, which is the optimal concentration range for valuable substance recovery efficiency; the volume ratio of the introduced air to the slurry is (5–10):1; introducing air can improve the homogeneity of the slurry by combining gas stirring and mechanical stirring, and the oxygen-rich conditions are beneficial for the removal of cyanide in subsequent pretreatment processes. The modifier includes sodium hexametaphosphate and sodium lignosulfonate in a mass ratio of 1:(0.8–1.2), and the amount of modifier added to the slurry is 200–300 g / t. The modifier can increase the dispersibility between sulfide minerals such as pyrite and fine-grained gangue minerals.

[0038] In step S1, the cyanide residue includes online cyanide residue and / or stockpiled cyanide residue. Online cyanide residue refers to the tailings slurry after dewatering by pressure filtration but before being stockpiled in the tailings dam; it can be directly fed into the slurry conditioning tank for conditioning. Stockpiled cyanide residue is fed into the recovery tank through hydraulic recovery and stirred. After being stirred evenly, it is fed into a thickener for solid-liquid separation, obtaining thickened underflow and overflow water. The overflow water is returned to the recovery integrated water tank, and the thickened underflow is fed into the slurry conditioning tank for conditioning. During hydraulic recovery, the slurry concentration needs to be controlled at 15%–25% to ensure stable feed to the thickener and guarantee the thickening effect.

[0039] In step S3, the filtrate obtained after dewatering the tailings slurry and concentrate slurry after flotation is returned to step S1 and recycled as hydraulic recovery water or slurry conditioning water.

[0040] In step S3, the flotation reagents include copper sulfate, butyl xanthate, butylammonium black reagent, and No. 2 oil. The addition amounts of the four reagents to the pretreated slurry are 250–350 g / t, 100–120 g / t, 40–60 g / t, and 20–40 g / t, respectively. The flotation process includes one roughing, three scavenging, and three cleaning stages. The quality of the cyanide gold concentrate obtained after flotation meets the requirements of "Cyanide Gold Concentrate," and the cyanide content meets the requirements of Article 8.3 of the "Technical Specification for Pollution Control of Cyanide Slag in the Gold Industry" (HJ 943-2018), which stipulates that "when cyanide slag is used as a substitute raw material for the smelting of non-ferrous metals, rare and precious metals, and ferrous metals, its total cyanide content, as measured by HJ 745, shall not exceed 1500 mg / kg." The tailings after flotation, after hazard identification (including corrosivity, reactivity, content of toxic substances, leaching toxicity, acute toxicity, and flammability), meet the requirements for general industrial solid waste.

[0041] Example 1

[0042] Please see Figure 1 As shown, this embodiment provides a method for recovering valuable substances from cyanide slag, including the following steps:

[0043] S1. The stockpiled cyanide slag is hydraulically extracted and the slurry concentration is controlled at 20%. It is then fed into the extraction tank and stirred. After being stirred evenly, it is pumped into a thickener for solid-liquid separation to obtain thickened underflow and overflow water. The overflow water is returned to the integrated water tank of the extraction tank, and the thickened underflow is fed into the slurry conditioning tank. During the stirring process, air is introduced with a volume ratio of air to slurry of 5:1. Sodium hexametaphosphate and sodium lignosulfonate are added at the same time and mixed evenly in a mass ratio of 1:1. The amount added is 230g / t. After stirring evenly, an adjusted slurry with a mass concentration of 30% is obtained.

[0044] S2. Input the adjusted slurry into the pretreatment tank, add acidic mine water to adjust the pH to 7.5, and simultaneously add a pretreatment agent. The pretreatment agent consists of diatomaceous earth and sodium metabisulfite, mixed evenly in a mass ratio of 0.1:1, with a dosage of 0.8 kg / m³. 3 Air is introduced at a volume ratio of 8:1 to the slurry, and the reaction is carried out for 2.0 hours. After the reaction is complete, a pretreated slurry is obtained.

[0045] S3. Input the pretreated slurry into the flotation cell, add 300 g / t of copper sulfate, 112.5 g / t of butyl xanthate, 56.5 g / t of butylammonium black powder, and 38 g / t of No. 2 oil. After one roughing, three scavenging, and three cleaning flotation processes, obtain the tailings slurry and concentrate slurry after flotation. Perform pressure filtration and dewatering treatment on the concentrate slurry to obtain the filtrate and the concentrate product, cyanide gold concentrate. Perform pressure filtration and dewatering treatment on the tailings slurry after flotation to obtain the filtrate and the tailings after flotation. Return the filtrate to step S1 for use as hydraulic recovery water and slurry conditioning water.

[0046] Regarding the Au, S, As, and CN in the concentrate of this embodiment T The total cyanide content was analyzed, and the specific results are shown in Table 1.

[0047] Table 1. Analysis of concentrate components obtained in Example 1

[0048]

[0049] As shown in Table 1, the concentrate product meets the relevant requirements of "Cyanide Gold Concentrate" and "Technical Specification for Pollution Control of Cyanide Slag in Gold Industry", indicating that this embodiment successfully prepared qualified cyanide gold concentrate product by using cyanide tailings and acidic mine wastewater.

[0050] CN in the slurry before and after pretreatment in this embodiment T (Total cyanide), CN f The content of (easily released cyanide) was analyzed, and the specific results are shown in Table 2.

[0051] Table 2. Analysis of cyanide content in pulp before and after pretreatment in Example 1.

[0052] Before pretreatment (mg / L) 148.27 131.66 After pretreatment (mg / L) 7.10 1.74 Pretreatment removal efficiency (%) 95.2％ 98.7％

[0053] As shown in Table 2, the cyanide content in the slurry phase was significantly reduced after pretreatment, and the cyanide removal rate reached over 95%, indicating that acidic mine water and pretreatment agent have a good synergistic effect in purifying cyanide slag.

[0054] In accordance with the relevant requirements of the General Rules for Identification of Hazardous Wastes (GB 5085.7-2019), the hazardous characteristics of the tailings obtained after flotation in step S3 of Example 1 were identified.

[0055] 1) Corrosion analysis

[0056] According to the "Standard for Identification of Hazardous Waste: Corrosivity Identification" (GB 5085.1-2007), the corrosivity of the tailings after flotation was tested and analyzed. The corrosivity of the tailings after flotation was 7.72, which does not meet the conditions of pH ≥ 12.5 or ≤ 2.0, indicating that it does not have corrosive hazardous characteristics.

[0057] 2) Leaching toxicity

[0058] According to the "Identification Standard for Hazardous Waste - Leaching Toxicity Identification" (GB 5085.3-2007), toxicity leaching tests were conducted on the tailings after flotation, and the specific results are shown in Table 3.

[0059] Table 3. Results of leaching toxicity analysis of tailings after flotation in Example 1

[0060]

[0061] As shown in Table 3, the leaching toxicity of the tailings after flotation did not exceed the leaching toxicity identification standard of "Identification Standard for Hazardous Waste" (GB 5085.3-2007), indicating that the tailings after flotation are very stable, heavy metals do not exist in ionic form, and do not have leaching toxicity hazards.

[0062] 3) Content of toxic substances

[0063] According to the requirements of the "Identification Standard for Hazardous Waste - Identification of Toxic Substance Content" (GB 5085.6-2007), the toxic substance content of the tailings after flotation was analyzed, and the specific results are shown in Table 4.

[0064] Table 4. Results of Detection of Toxic Substance Content in Tailings After Flotation in Example 1

[0065]

[0066]

[0067] The identification of inorganic toxic substance content requires converting heavy metal content into the content of inorganic toxic compounds that produce heavy metals. Based on the toxic substances in Appendices A to F of the "Identification Standard for Toxic Substance Content" (GB5085.6-2007) and the tailings generation process, the following judgments are made:

[0068] (1) The silver in the appendix is ​​only silver cyanide compound, and the total cyanide of the rest is calculated according to sodium cuprous cyanide;

[0069] (2) Arsenic exists in the ore in two states: sulfide and oxide. Sulfide is not listed in the appendix. This calculation considers the worst-case scenario, and all arsenic is calculated as calcium arsenate.

[0070] (3) Other metal elements are required to comply with Article 7.4 of the Technical Specification for Identification of Hazardous Waste (HJ 298-2019): "When judging the hazardous characteristics of toxic substances, if the same toxic component exists in more than one toxic substance, the substance with the highest molecular weight shall be used for calculation and result judgment."

[0071] The selection of compounds in the calculation of the toxic substance content of tailings after flotation is shown in Table 5.

[0072] Table 5 Summary of Calculation Results of Toxic Substance Content in Tailings After Flotation in Example 1

[0073]

[0074]

[0075] Note: 1) These are compounds selected only when calculating toxic substances based on the worst-case scenario, and do not represent the actual presence of these compounds in the waste; 2) The standard limits are from the "Identification Standard for Hazardous Waste - Identification of Toxic Substance Content" (GB 5085.6-2007); 3) Calculated as calcium arsenate; 4) Calculated as beryllium carbonate.

[0076] As shown in Table 5, the content of individual toxic substances in the tailings after flotation is lower than the limit value of toxic substances, and the cumulative toxicity is much less than 1, indicating that it does not have the dangerous characteristics of toxic substance content.

[0077] 4) Acute toxicity

[0078] According to the requirements of the "Identification Standard for Hazardous Waste - Acute Toxicity Screening" (GB 5085.2-2007), the toxic substance content of the tailings after flotation was analyzed, and the specific results are shown in Table 6.

[0079] Table 6. Calculation of Acute Toxicity of Tailings After Flotation in Example 1

[0080]

[0081] Note 1) The selection of compounds takes into account the content of substances (C). i and LD 50 According to C i / ATE i The selection of compounds based on the greatest adverse event principle does not necessarily mean they are actually present in waste; 2) Acute toxicity data are from the Chemical Toxicity Database and the Chemical Book. The test species is selected according to 4.3.6.2 of the "Classification and Labelling Specifications for Chemicals Part 18: Acute Toxicity" (GB30000.18-2013), which states that "the preferred test species for assessing acute toxicity via the oral route is the rat." Therefore, the LD50... 50 Data is preferentially selected from rats; mice are selected only when rat data is unavailable. 3) The acute oral toxicity category of beryllium nitrate is 3; when no relevant data is available, the lower limit value of the corresponding category is selected based on the acute toxicity category. 4) C is unknown; the worst-case scenario principle is followed. 未知 =(100-Moisture-∑C 1-11 ).

[0082] As shown in Table 6, the LD20 extracted from the tailings after flotation can be obtained by oral intake. 50 The minimum value is much greater than 200 mg / kg, and it does not have acute toxicity risk characteristics.

[0083] 5) Flammability

[0084] According to the requirements of the "Identification Standard for Hazardous Waste - Flammability Identification" (GB 5085.4-2007), the main component of the tailings after flotation is silicon dioxide, which does not contain flammable substances, and thus the flammable hazard characteristics can be ruled out.

[0085] 6) Reactivity

[0086] According to the requirements of the "Identification Standard for Hazardous Waste - Reactivity Identification" (GB 5085.5-2007), the toxicity content of the tailings after flotation was analyzed, and the specific results are shown in Table 7.

[0087] Table 7 Results of Reactivity Test of Tailings after Flotation in Example 1

[0088] Detection value 0.13 Not detected Standard Limit 250 500

[0089] As shown in Table 7, the reactivity of the tailings after flotation did not exceed the leaching toxicity identification standard of the "Identification Standard for Hazardous Wastes" (GB5085.3-2007), and it did not have any reactive hazardous characteristics.

[0090] The results above show that, after processing and recovering the valuable substances from the cyanide slag using the method provided in this embodiment, the concentrate product meets the relevant requirements of "Cyanide Sulfate Gold Concentrate" and "Technical Specification for Pollution Control of Cyanide Slag in the Gold Industry," achieving efficient recovery of valuable substances and making it suitable for external sale. Simultaneously, the use of mine acidic water for co-purification of the cyanide slag, and the tailings after flotation, after hazardous characteristic identification, meet the requirements for general industrial solid waste.

[0091] Comparative Examples 1-4

[0092] Comparative Examples 1-4 each provide a method for recovering valuable substances from cyanide slag. The difference compared to Example 1 is that in Comparative Example 1, acidic mine water is not added in step S2; instead, sulfuric acid is used to adjust the pH value. In Comparative Example 2, acidic mine water is not added in step S2; instead, sulfuric acid is used to adjust the pH value. The pretreatment agent dosage is 1.6 kg / m³. 3 In Comparative Example 3, the pH value of the mine acidic water was adjusted to 8.5 in step S2. No pretreatment agent was added in Comparative Example 4. The corresponding parameters of each comparative example are shown in Table 8. The remaining parameters are the same as those of Example 1, and will not be repeated here.

[0093] Table 8 Process parameters for Comparative Examples 1-4

[0094]

[0095] After recovering valuable substances from the cyanide slag using the methods provided in Comparative Examples 1-4, the concentrate and tailings after flotation were tested, and the results are shown in Table 9.

[0096] Table 9 Summary of Experimental Results for Comparative Examples 1–4

[0097]

[0098] As shown in Table 9, in Comparative Example 1, the use of sulfuric acid to adjust the pH value resulted in inefficient cyanide removal, and the concentrate did not meet the requirements for cyanide-gold concentrate products. The tailings after flotation were classified as hazardous waste. In Comparative Example 2, the pH value was adjusted using sulfuric acid, and the pretreatment agent dosage was increased to 1.6 kg / m³. 3 The removal rate was double that of the previous example, but still lower than that of the example with added acidic mine water. The sulfur content in the concentrate did not meet the quality requirements for cyanide-gold concentrate. In Comparative Example 3, adjusting the pH to above 8.2 directly affected the cyanide removal effect, resulting in concentrate that did not meet the requirements for cyanide-gold concentrate, and the tailings after flotation were classified as hazardous waste. In Comparative Example 4, without adding pretreatment agents, the cyanide removal effect was poor, the concentrate did not meet the requirements for cyanide-gold concentrate, and the tailings after flotation were classified as hazardous waste.

[0099] Example 2

[0100] This embodiment provides a method for recovering valuable substances from cyanide slag. Compared with Embodiment 1, the difference is that the online cyanide slag is used in step S1 for slurry preparation. Specifically, in step S1, the online cyanide slag is input into the slurry preparation tank, and air is introduced during the stirring process. The volume ratio of air to slurry is 5:1. Sodium hexametaphosphate and sodium lignosulfonate are added at the same time and mixed evenly in a mass ratio of 1:1. The amount added is 230g / t. After stirring evenly, a slurry with a mass concentration of 30% is obtained. The remaining steps are the same as in Embodiment 1 and will not be repeated here.

[0101] The concentrate produced in Example 2 was analyzed and found to contain 3.13 g / t of Au and 42.63% of S, meeting the requirements for gold cyanide concentrate products. The tailings after flotation were also analyzed for hazardous characteristics and met the requirements for general industrial solid waste.

[0102] In summary, this invention provides a method for recovering valuable substances from cyanide slag. Through a rationally designed processing technology, the cyanide slag is sequentially subjected to slurry preparation, pretreatment, and flotation to recover valuable substances. The pretreatment process effectively removes the inhibitory effect of cyanide on flotation, ensuring that the recovered concentrate meets the requirements of cyanide sulfide gold concentrate products, thus achieving efficient recovery of valuable substances. Furthermore, based on the green and ecological development concept of "treating waste with waste and turning waste into treasure," this invention uses acidic mine water to co-purify the cyanide slag, reducing the amount of pretreatment agent added, lowering the cost of cyanide slag recovery, and also utilizing acidic mine wastewater from industry, improving resource recovery efficiency. Moreover, the tailings after flotation meet the requirements of general industrial solid waste, significantly reducing the environmental risks of solid waste stockpiling. The method for recovering valuable substances from cyanide slag is simple in process, safe and reliable in operation, and uses acidic mine water to purify the cyanide slag. It can efficiently recover valuable substances from cyanide slag, and simultaneously remove toxic components from cyanide slag and acidic mine water. At the same time, the tailings after flotation meet the requirements of general industrial solid waste. It has significant economic, environmental and social benefits, and provides a new approach for the comprehensive utilization of cyanide slag.

[0103] The above 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 with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for recovering valuable substances from cyanide slag, characterized in that, Includes the following steps: S1. The cyanide slag is slurried to obtain slurry, and air is introduced into the slurry and a modifier is added to obtain the slurry. S2. Add acidic mine water to the slurry as described in step S1 to adjust the pH value, and add a pretreatment agent at the same time. After the reaction is complete, a pretreated slurry is obtained. S3. Add flotation agent to the pretreated slurry in step S2 for flotation to obtain tailings slurry and concentrate slurry after flotation. Perform pressure filtration and dewatering treatment on the concentrate slurry to obtain filtrate and cyanide gold concentrate. Perform pressure filtration and dewatering treatment on the tailings slurry after flotation to obtain filtrate and tailings after flotation. In step S2, the acidic mine water is wastewater containing one or more of the following: iron, manganese, copper, lead, zinc, cadmium, chromium, arsenic, and nickel. The acidic mine water is used to adjust the pH of the slurry to 7.4-8.

2. In step S2, the pretreatment agent is a mixture of diatomaceous earth and sodium sulfite, or diatomaceous earth and sodium metabisulfite, wherein the mass ratio of diatomaceous earth to sodium sulfite or sodium metabisulfite is (0.05~0.2):1; In step S2, the amount of the pretreatment agent added is 0.5~2.0 kg / m³. 3 When the pretreatment agent is a mixture of diatomaceous earth and sodium metabisulfite, air is simultaneously introduced into the conditioning slurry, and the volume ratio of air to the conditioning slurry is (5~10):

1. In step S1, the modifier comprises sodium hexametaphosphate and sodium lignosulfonate in a mass ratio of 1:(0.8~1.2), and the amount of the modifier added to the slurry is 200~300 g / t.

2. The method for recovering valuable substances from cyanide slag according to claim 1, characterized in that, In step S1, the mass concentration of the slurry is adjusted to 30%~35%, and the volume ratio of the air introduced to the slurry is (5~10):

1.

3. The method for recovering valuable substances from cyanide slag according to claim 1, characterized in that, In step S3, the flotation agent includes copper sulfate, butyl xanthate, butylammonium black and No. 2 oil, and the addition amounts of the above four agents in the pretreated slurry are 250~350 g / t, 100~120 g / t, 40~60 g / t and 20~40 g / t, respectively.

4. The method for recovering valuable substances from cyanide slag according to claim 1, characterized in that, In step S1, the cyanide residue includes online cyanide residue and / or stockpiled cyanide residue. The online cyanide residue can be directly fed into the slurry conditioning tank for slurry conditioning. The stockpiled cyanide residue is fed into the recovery tank through hydraulic recovery and stirred. After being stirred evenly, it is fed into a thickener for solid-liquid separation to obtain thickened underflow and overflow water. The overflow water is returned to the recovery integrated water tank, and the thickened underflow is fed into the slurry conditioning tank for slurry conditioning.

5. The method for recovering valuable substances from cyanide slag according to claim 4, characterized in that, In step S3, the filtrate obtained after the tailings slurry and concentrate slurry are dewatered by pressure filtration is returned to step S1 and recycled as hydraulic recovery water or slurry conditioning water.

6. The method for recovering valuable substances from cyanide slag according to claim 1, characterized in that, In step S3, the flotation process includes one roughing, three scavenging, and three cleaning.

Images