A method for modifying copper tailings into a class i general industrial solid waste

Abstract

The application discloses a method for modifying copper tailings into general industrial solid waste of the first type, and belongs to the technical field of solid waste treatment. The method comprises the following steps: S1, screening potential characteristic pollutants of the copper tailings; S2, determining the pH value of the copper tailings; determining the characteristic pollutants and the leaching concentration of the characteristic pollutants; S3, screening potential modification materials through mechanism analysis; S4, testing whether the mixing of the copper tailings and the potential modification materials will lead to the increase of the leaching concentration of the characteristic pollutants and the reactivity, and screening the modification materials; S5, obtaining the mixing ratio for modifying the pH value of the copper tailings and the leaching concentration of the characteristic pollutants to meet the general industrial solid waste of the first type; and S6, modifying the copper tailings according to the mixing ratio obtained in S5. The method can effectively control the pollution characteristics of the copper tailings, and solves the problems of the copper tailings, such as the difficulty in upgrading the environmental pollution prevention and control facilities of the copper tailings, the poor impermeability, the great risk of pollutant leakage and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste treatment, and relates to a solid waste treatment method, in particular to a method for modifying copper tailings into class I general industrial solid waste. BACKGROUND

[0002] Tailings account for a large proportion of general industrial solid waste, and currently face urgent disposal needs. In environmental management work for solid waste pollution prevention and control, solid waste is divided into class I and class II general solid waste, and different pollution characteristics classification corresponds to different management requirements.

[0003] The "General Industrial Solid Waste Storage and Landfill Pollution Control Standard" provides that "class I general industrial solid waste (class I non-hazardous industrial solid waste) is general industrial solid waste whose leaching liquid obtained according to the method specified in HJ 557 does not exceed the maximum allowable emission concentration of GB 8978 (the maximum allowable emission concentration of the second pollutant is executed according to the first standard), and the pH value is within the range of 6-9; class II general industrial solid waste (class II non-hazardous industrial solid waste) is general industrial solid waste whose leaching liquid obtained according to the method specified in HJ 557 has one or more than one concentration of characteristic pollutants exceeding the maximum allowable emission concentration of GB 8978 (the maximum allowable emission concentration of the second pollutant is executed according to the first standard), or the pH value is outside the range of 6-9."

[0004] The classification in the standard provides different pollution control technical requirements for class I and class II general industrial solid waste storage sites, landfill sites, and tailings ponds in construction (site selection, impermeability, groundwater drainage, etc.), operation (entry requirements, storage, transportation, etc.), and site closure, etc. For example, in terms of impermeability requirements, the natural base layer of the class I site has a saturated permeability coefficient of not more than 1.0×10 - 5 cm / s, and a thickness of not less than 0.75 m, the natural base layer can be used as an impermeable liner, and if it cannot be met, a modified compacted clay liner or other material with the same or higher water resistance can be used as an impermeable liner, and the class II site should use a single artificial composite liner as an impermeable liner, the artificial synthetic material should use a high-density polyethylene film with a thickness of not less than 1.5 mm, and the clay liner should have a thickness of not less than 0.75 m, and the saturated permeability coefficient after compaction, artificial modification, and other measures should be not more than 1.0×10 -7In addition, the surface of the Class II field foundation layer should be kept at a distance of 1.5 m above the annual highest water level of underground water, and when the distance between the surface of the field foundation layer and the annual highest water level of underground water is less than 1.5 m, an underground water drainage system should be constructed. Thus, it can be seen that there are great differences in pollution prevention and control requirements for Class I and Class II general industrial solid wastes in the actual management process.

[0005] Copper tailings are one of the main minerals in tailings industrial solid wastes. Due to the differences in pollution characteristics, part of the copper tailings cannot stably meet the requirements of Class I general industrial solid wastes. However, due to the early construction of tailings reservoirs, the environmental pollution prevention and control facilities such as impermeable performance, leachate collection system and underground water drainage system all have different degrees of problems such as functional defects and poor effects. The difficulty of later improvement and rectification engineering is extremely great, the investment is extremely high, the treatment cost of downstream heavy metal pollution problems is extremely great, and a series of environmental problems are generated. SUMMARY

[0006] The present application provides a method for modifying copper tailings into Class I general industrial solid waste to overcome the defects of the prior art.

[0007] To achieve the above-mentioned object, the present application adopts the following technical scheme:

[0008] The application discloses a method for modifying copper tailings into general industrial solid waste of the first category, which comprises the following steps: S1, screening potential characteristic pollutants of the copper tailings; S2, measuring the pH value of the copper tailings; determining the characteristic pollutants and the leaching concentration of the characteristic pollutants according to the potential characteristic pollutants; S3, screening general industrial solid waste capable of adjusting the pH value of the copper tailings and reducing the leaching concentration of the characteristic pollutants as potential modification materials through mechanism analysis; when the pH value of the copper tailings is less than 6, selecting alkaline general industrial solid waste as the potential modification materials for neutralization modification; the alkaline general industrial solid waste is one or more of fly ash, steel slag and lead-zinc tailings in an alkaline flotation process; when the leaching concentration of the characteristic pollutants exceeds the standard, selecting alkaline binder type general industrial solid waste as the potential modification materials for encapsulation modification; specifically, the encapsulation modification refers to that heavy metals are wrapped in a solidification matrix by adding alkaline binder type general industrial solid waste, so as to form insoluble or low-migration compounds, thereby significantly reducing the leaching rate of the heavy metals, that is, water and oxygen are blocked by the encapsulation method, and the dissolution of the heavy metals is inhibited; the alkaline binder is one or more of sodium silicate (Na2SiO3), potassium silicate (K2SiO3), lime-based (Ca (OH)2) and lead-zinc tailings in an alkaline flotation process; or, selecting sulfide-containing general industrial solid waste as the potential modification materials to make heavy metals generate insoluble precipitates for chemical modification; the sulfide-containing general industrial solid waste is non-ferrous metal smelting slag; S4, testing whether the mixing of the copper tailings and the potential modification materials will cause the leaching concentration of the characteristic pollutants to increase and be reactive; screening the potential modification materials which do not cause the leaching concentration of the characteristic pollutants to increase and be reactive as modification materials; S5, modifying the copper tailings and the modification materials in different proportions to obtain a proportioning scheme for modifying the pH value of the copper tailings and the leaching concentration of the characteristic pollutants to meet the general industrial solid waste of the first category; and S6, modifying the copper tailings according to the proportioning scheme obtained in S5.

[0009] To optimize the above technical solution, the following specific measures are taken:

[0010] Further, the method for screening the characteristic pollutants in S1 is as follows: according to the metal mine for producing the copper tailings and the raw and auxiliary materials and the beneficiation process of the metal mine, the types of heavy metals such as copper (Cu), arsenic (As), zinc (Zn), lead (Pb), cadmium (Cd) and mercury (Hg) in the copper tailings are determined as the potential characteristic pollutants.

[0011] Further, the method for determining the pH value and the leaching concentration of the characteristic pollutants of the copper tailings in S2 is as follows: collecting the copper tailings sample, preparing the copper tailings leaching solution according to the “Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method (HJ557-2010)”, determining the pH value of the copper tailings leaching solution, detecting the concentration of the potential characteristic pollutants in the copper tailings leaching solution, determining the potential characteristic pollutants that are detected and exceed the standard limit value as the characteristic pollutants, and determining the concentration of the detected characteristic pollutants as the leaching concentration of the characteristic pollutants.

[0012] Further, the method for collecting the copper tailings sample in S2 is as follows: according to the production amount of the copper tailings in one production cycle, the copper tailings sample is collected by the systematic distribution method or the equal time interval method.

[0013] Further, the reactivity in S4 means that the copper tailings and the potential modification material are mixed to cause obvious exothermic reaction, ignition, explosion, polymerization or generation of toxic and harmful substances.

[0014] Further, the method for obtaining the ratio in S5 includes the following steps: S5.1, mixing the copper tailings with the modification material (if the modification material is multiple, the copper tailings can be mixed with multiple modification materials) to modify, and setting up experimental groups according to different ratios; S5.2, determining the pH value and the leaching concentration of the characteristic pollutants of each experimental group after modification; S5.3, determining the experimental group in which the pH value and the leaching concentration of the characteristic pollutants meet the Class I general industrial solid waste, and taking the ratio of the experimental group as the ratio.

[0015] Further, in S5.3, when the ratio is determined, the experimental group in which the pH value and the leaching concentration of the characteristic pollutants meet the Class I general industrial solid waste is selected, the experimental group in which the amount of the modification material added is the least is selected, and the ratio of the experimental group is taken as the ratio.

[0016] The beneficial effects of the present application are that the present application aims at the current large amount of copper tailings which cannot stably reach the general industrial solid waste of Class I, and the problem of improper utilization and disposal under the condition that the pollutants in the copper tailings do not meet the standard, and provides a method for modifying the copper tailings into the general industrial solid waste of Class I. The method of the present application can reduce the leaching concentration of pollutants in the copper tailings, reduce and control the pollutants from the source, reduce the engineering cost and implementation difficulty of tailings pond treatment, effectively control the pollution characteristics of the copper tailings, and fully solve the problems of difficult environmental pollution prevention and control facility modification and upgrading of the current copper tailings pond, high engineering difficulty and cost, poor impermeability, extensive environmental management, and high risk of pollutant leakage. The method of the present application has clear ideas and accurate problem identification, and is fully applicable to guide the modification of copper tailings, and guide the design, operation and other environmental management requirements of the general industrial solid waste storage and disposal site of the tailings pond. DETAILED DESCRIPTION

[0017] The present application will be further described below in conjunction with specific embodiments.

[0018] The present embodiment provides a method for modifying copper tailings into the general industrial solid waste of Class I, which is used for modifying and treating the copper tailings generated by a large-scale ore dressing enterprise in Jiangxi Province, and the conclusion is applied to the storage and operation environmental management of the copper tailings in the tailings pond. The mining area of the enterprise is 3 km 2 Above all, the enterprise mainly engages in copper mining and lead-zinc mining, and the main products are copper concentrate, sulfur concentrate and lead-zinc concentrate. At present, copper ore is mined by open-pit and underground mining methods, with a daily output of 13000 tons of copper ore, an annual output of 61180 tons of copper concentrate (containing 21% of copper, 38.74g / t of silver, 13.29g / t of gold and 27.43% of sulfur), and lead-zinc ore is mainly mined underground, with a daily output of 500 tons of lead-zinc ore, and a service life of 19 years. According to the relevant production materials provided by the enterprise, the enterprise tailings mainly go to the pit / underground filling and tailings pond storage, and the production of the enterprise copper tailings from January 2023 to December 2023 is 259047t, 332003t, 246978t, 346549t, 345441.0, 347296t, 313961t, 301042t, 312732t, 264567t, 320047t, 358387t, respectively, and the production is relatively stable.

[0019] The method comprises the following steps:

[0020] S1, carry out potential characteristic pollutant screening of copper tailings.

[0021] The main heavy metals and contents in the copper ore producing copper tailings are shown in Table 1.

[0022] Table 1 Main heavy metals and content in copper ore

[0023]

[0024] Main raw and auxiliary materials and physicochemical property analysis: The raw and auxiliary materials used by the enterprise in the flotation of copper ore include: ethyl xanthate (sodium ethyl xanthate), yellow powder solid at room temperature, easily soluble in water, acetone and corresponding alcohol, pure product has a slight odor, widely used in the flotation of easy-to-float sulfide ore and the preferential flotation of complex sulfide ore, the usage is 118.8 t / a; butyl xanthate (C4H6OCSSNa), light yellow powder or granules with irritating odor, soluble in water and alcohol, is a strong collecting agent for flotation of non-ferrous metal sulfide ore, the usage is 105.6 t / a; thiamine (z-200), light yellow oily liquid with slight irritating odor, hardly soluble in water, easily soluble in ethanol, diethyl ether, benzene and petroleum ether. It is a good collector for non-ferrous metal sulfide ore, the usage is 66 t / a; 2# oil (complex high alcohol), divided into pine oil and chemical oil, used as a foaming agent in non-ferrous metal flotation, yellow to brown oily liquid, slightly soluble in water, density is smaller than water, has irritating odor, the usage is 135.432 t / a; lime, main component is calcium oxide, used to prepare lime milk, is a pH regulator, is a sulfur inhibitor in metal ore dressing, the usage is 13200 t / a; arsenic inhibitor, the functional groups of the ore dressing arsenic inhibitor are various, the central atoms are N, O, S and P, the types of functional groups are -OH, -COOH, -NH2, -SO3H, -C(S)SH, phenylmercury and quinol, the usage is 607.2 t / a; dilute sulfuric acid, the usage is 580.8 t / a; flocculant, the usage is 6.92 t / a.

[0025] Copper ore dressing process analysis: The semi-autogenous grinding-ball grinding-stone crushing crushing process is adopted for the pre-treatment of copper ore dressing. The coarse crushing is arranged underground, the product particle size of coarse crushing is ~ 300 mm, the product fineness of ball grinding is ~ 0.074 mm, accounting for 65%. The product fineness of coarse concentrate regrinding is ~ 0.045 mm, accounting for 80%. The mixed flotation-coarse concentrate regrinding-copper-sulfur separation flotation process is adopted for copper ore dressing. The copper-sulfur mixed flotation operation is composed of two times of roughing and two times of scavenging, and the mixed coarse concentrate and the final tailings are produced. The mixed coarse concentrate enters the copper-sulfur separation flotation operation after regrinding, and the copper-sulfur separation flotation is composed of one roughing column roughing, one roughing column cleaning and two times of scavenging, and finally the copper concentrate and the sulfur concentrate are obtained. The sulfur coarse concentrate is concentrated by high-efficiency thickener and then subjected to sulfur flotation system, and the sulfur selection is composed of one roughing, one scavenging and two cleanings.

[0026] According to the above copper ore (copper ore contains a certain amount of mercury, cadmium, arsenic, lead, copper, zinc and manganese and other heavy metals), the main raw and auxiliary materials and physicochemical property analysis and mineral processing process analysis results, the potential characteristic pollutants of copper tailings can be determined, including the first class pollutants mercury, cadmium, arsenic, lead, and the second class pollution pH value, copper, zinc, manganese.

[0027] S2, measuring the pH value of the copper tailings, and determining the characteristic pollutants and the leaching concentration of the characteristic pollutants according to the potential characteristic pollutants detection.

[0028] Firstly, the copper tailings samples are collected. Specifically, the sampling method is determined: sampling at equal time intervals at the tailings production point, and the mass of each sample is not less than 1 kg; the number of sample portions is determined: taking one month as a stable production batch, the output of copper tailings is about 31.25 million tons / month, and for batches ≥10000 t, the minimum number of copper tailings sample portions is determined to be 80; the sampling cycle is determined: under stable working conditions, solid waste samples are collected at equal time intervals, i.e. one month of stable working condition production is taken as a cycle, and 1 sample is collected at 8:00, 12:00 and 16:00 every day within 1 month, a total of 80 copper tailings samples are collected, as shown in Table 2.

[0029] Table 2 Copper tailings sampling table

[0030]

[0031] Then, the copper tailings leaching liquid is prepared according to the method specified in HJ 557, and the pH value and potential characteristic pollutants are measured.

[0032] The detection results of the 80 collected copper tailings show that the pH value is between 5.08 and 8.63; the detection rates of the first class characteristic pollutants mercury and arsenic are both 100%, the concentrations are between 4×10 -5 ~3.8×10 -4 mg / L and 1.14×10 -3 ~0.022 mg / L, respectively, and other cadmium and lead are not detected; the detection rate of the second class pollutant manganese is 100%, the concentration is between 0.0115 and 1.58 mg / L, the detection rate of zinc is 28.75%, the concentration is between 0.07 and 0.58 mg / L, and the detection rate of copper is 22.5%, the concentration is between 0.03 and 0.62 mg / L. The detection results are shown in Table 3.

[0033] Table 3 Detection results of copper tailings (detection range unit: heavy metals mg / L, pH value is dimensionless)

[0034]

[0035] According to the above detection results, copper is determined as a characteristic pollutant.

[0036] S3, through mechanism analysis, screening other different types of general industrial solid wastes that can adjust the pH value of copper tailings and reduce the leaching concentration of characteristic pollutants as potential modification materials.

[0037] Specifically, since the pH value of copper tailings is lower than 6 and there is a characteristic pollutant copper, the lead-zinc tailings with alkaline flotation process are selected as potential modification materials for modification. The lead-zinc tailings with alkaline flotation process are not only alkaline general industrial solid wastes that can adjust the pH value, but also alkaline binders that can encapsulate and modify heavy metal copper, and the enterprise also produces a certain amount of lead-zinc tailings in the beneficiation process, therefore, the lead-zinc tailings are preferred as potential modification materials for modification of copper tailings.

[0038] 80 samples of lead-zinc tailings are collected and detected, and the detection results show that the pH value is between 7.21~8.89; the detection rates of the first type of characteristic pollutants mercury and arsenic are both 100%, the concentrations are between 5×10 -5 ~4.8×10 -4 mg / L and 3.61×10 -3 ~0.0474 mg / L, cadmium and lead are not detected; the detection rate of the second type of pollutant zinc is 1.25%, the concentration is 0.06 mg / L, copper is not detected; other characteristic pollutants thallium are not detected. The detection results are shown in Table 4.

[0039] Table 4 Detection results of lead-zinc tailings (detection range unit: heavy metal mg / L, pH value is dimensionless)

[0040]

[0041] Through detection, it can be determined that the lead-zinc tailings will not introduce new characteristic pollutants, and can be used as potential modification materials.

[0042] S4, compatibility test is carried out. The copper tailings are mixed with the lead-zinc tailings, and after mixing, no obvious exothermic, ignition, explosion, polymerization or production of toxic and harmful substances and other reactions occur, and the leaching concentration of heavy metals does not increase obviously. Therefore, the lead-zinc tailings are selected as modification materials.

[0043] S5, by mixing copper tailings with modification materials in a certain proportion, the leaching concentration level of characteristic pollutants is optimized, and the proportion of copper tailings and modification materials is obtained to modify the pH value and the leaching concentration of characteristic pollutants to meet the requirements of the first type of general industrial solid waste.

[0044] S5.1, the copper tailings and lead-zinc tailings are mixed, and experimental groups are set up according to different proportions. Specifically, the copper tailings and lead-zinc tailings are mixed and modified according to different mass ratios of 1:1, 2:1, 3:1, 4:1 and 5:1, and are marked as experimental groups 1-5#, 20 samples are prepared for each group, and so on.

[0045] S5.2, the pH value and the leaching concentration of characteristic pollutants of the mixed and modified experimental groups are determined, and the results are shown in Table 5.

[0046] Table 5: Test results of experimental groups (detection range unit: heavy metal mg / L, pH value is dimensionless)

[0047]

[0048] S5.3, determine the experimental group that can stably reach the pH value and the leaching concentration of characteristic pollutants of the first general industrial solid waste. As can be seen from Table 4, the pH value of experimental group 4# with a ratio of 4:1 is lower than 6, and the copper leaching concentration of one sample in experimental group 5# with a ratio of 5:1 is higher than 0.5 mg / L, therefore, the copper tailings can be modified to stably reach the standard while achieving the minimum amount of addition in experimental group 3# with a ratio of not more than 3:1. Therefore, the mass ratio of experimental group 3# is the determined modification ratio.

[0049] S6, modify the copper tailings according to the ratio obtained in S5. Specifically, the ratio of copper tailings to lead-zinc tailings is not more than 3:1, and the pollutant concentration limit value requirement of the first general industrial solid waste is stably reached. The copper tailings storage that meets the requirements of the first general industrial solid waste can be constructed, operated and long-term monitored according to the requirements of the first class field.

[0050] In the present application, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. And the reagents, materials and operation steps used herein are widely used reagents, materials and conventional steps in the corresponding field.

[0051] Finally, it should be pointed out that: the above only describes the preferred embodiments of the present application and is not used to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacement for part of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for modifying copper tailings into general industrial solid waste of Class I, characterized in that it comprises the following steps: S1, screening potential characteristic pollutants of copper tailings; S2, determining the pH value of copper tailings and the leaching concentration of characteristic pollutants by collecting copper tailings samples, preparing copper tailings leaching solution, determining the pH value of copper tailings leaching solution, detecting the concentration of potential characteristic pollutants in copper tailings leaching solution, determining the potential characteristic pollutants detected and exceeding the standard limit value as characteristic pollutants, and determining the concentration of detected characteristic pollutants as the leaching concentration of characteristic pollutants; S3, screening general industrial solid waste capable of adjusting the pH value of copper tailings and reducing the leaching concentration of characteristic pollutants as potential modification materials through mechanism analysis; when the pH value of copper tailings is less than 6, selecting alkaline general industrial solid waste as potential modification materials for neutralization modification; the alkaline general industrial solid waste is one or more of fly ash, steel slag and lead-zinc tailings with alkaline flotation process; when the leaching concentration of characteristic pollutants exceeds the standard, selecting alkaline binder type general industrial solid waste as potential modification materials for encapsulation modification; the alkaline binder is one or more of sodium silicate, potassium silicate, lime-based and lead-zinc tailings with alkaline flotation process; and / or, selecting sulfide-containing general industrial solid waste as potential modification materials for chemical modification by making heavy metals generate insoluble precipitates; the sulfide-containing general industrial solid waste is non-ferrous metal smelting slag; S4, testing whether the mixture of copper tailings and potential modification materials will cause the leaching concentration of characteristic pollutants to increase and have reactivity; screening potential modification materials that do not cause the leaching concentration of characteristic pollutants to increase and have reactivity as modification materials; S5, obtaining the ratio of copper tailings and modification materials for modification according to different proportions to modify the pH value of copper tailings and the leaching concentration of characteristic pollutants to meet the general industrial solid waste of Class I; S6, modifying copper tailings according to the ratio obtained in S5.

2. The method for modifying copper tailings into general industrial solid waste of Class I according to claim 1, characterized in that: the method for screening characteristic pollutants in S1 is to determine the type of heavy metals in copper tailings as the potential characteristic pollutants according to the metal ore producing copper tailings and the raw and auxiliary materials and beneficiation process of metal ore beneficiation process.

3. The method for modifying copper tailings into general industrial solid waste of Class I according to claim 1, characterized in that: the method for collecting copper tailings samples in S2 is to collect the copper tailings samples by systematic point method or equal time interval method according to the production amount of copper tailings in one production cycle.

4. The method for modifying copper tailings into general industrial solid waste of Class I according to claim 1, characterized in that: the reactivity in S4 means that the mixture of copper tailings and potential modification materials will have obvious exothermic, ignition, explosion, polymerization or produce toxic and harmful substances.

5. The method for modifying copper tailings into general industrial solid waste of Class I according to claim 1, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The method for obtaining the ratio in S5 comprises the following steps: S5.1, mixing and modifying the copper tailings with the modified material, and setting experimental groups according to different ratios; S5.2, measuring the pH value and the leaching concentration of the characteristic pollutants of each experimental group after modification; S5.3, determining the experimental group whose pH value and leaching concentration of the characteristic pollutants meet the general industrial solid waste of the first category, and taking the ratio of the experimental group as the ratio.

6. The method for modifying the copper tailings into the general industrial solid waste of the first category according to claim 5, characterized in that: When the ratio is determined in S5.3, the experimental group with the least amount of the modified material is selected from the experimental groups whose pH value and leaching concentration of the characteristic pollutants meet the general industrial solid waste of the first category, and the ratio of the experimental group is taken as the ratio.

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