Method for detecting heavy metal leaching from gold tailings concrete and device thereof

Abstract

This application relates to a method and apparatus for detecting heavy metal leaching in gold tailings concrete. The method includes the following steps: preparing a concrete specimen; collecting permeate; using three adjacent faces of the specimen at the same corner as permeation surfaces, and the other three faces as pressurized water injection surfaces; employing an anti-permeability penetration method to ensure permeate flows out from the permeation surfaces of the specimen, maintaining a consistent inclination angle among the three permeation surfaces; continuously collecting the permeate flowing out from the three surfaces of the specimen; detecting the final heavy metal ion concentration in the permeate; and finally calculating the heavy metal leaching amount per unit volume of concrete. The apparatus includes an anti-permeability body and a specimen fixing assembly. The specimen fixing assembly includes a base and a mold base, forming a specimen cavity between the base and the mold base that matches the regular hexahedral specimen. The top of the mold base has a permeation port for permeate leakage. This application improves the accuracy of detecting heavy metal ion leaching in gold tailings concrete.

Description

Technical Field

[0001] This application relates to the field of heavy metal detection technology, and in particular to a method and apparatus for detecting heavy metal leaching from gold tailings concrete. Background Technology

[0002] The high-value application of gold tailings in concrete opens up new possibilities for resource recycling. Incorporating gold tailings into concrete raw materials not only helps alleviate the problem of waste tailings accumulation but also fully utilizes their inherent valuable components. However, before implementing this application, it is essential to rigorously test the heavy metal content in the tailings to ensure that it has no adverse effects on the environment and human health.

[0003] Detecting the leaching of heavy metals from tailings concrete is the primary step in achieving the green and comprehensive utilization of tailings, laying a solid foundation for the full utilization value of tailings. In particular, toxic heavy metals, such as Cd, Cr, Cu, Mn, Ni, and Pb, exhibit significant biotoxicity. Once these elements enter surface water systems, they exist in stable valence states and are difficult for microorganisms to decompose. Furthermore, their chemical forms can transform, disperse, and migrate with environmental changes, making them difficult to remove from soil. The hazards of heavy metals are immense; even trace concentrations can cause significant harm.

[0004] Traditional heavy metal leaching testing methods are primarily designed for the leaching of toxic ions from tailings, involving the crushing of tailings followed by impregnation. However, unlike tailings, the service environment of concrete and its inherent properties after hydration and solidification significantly influence the leaching process of heavy metal ions. Directly applying these traditional methods may yield results that fail to accurately reflect or predict the leaching status of cement concrete. To date, there is no reliable leaching testing method for assessing the leaching of heavy metal ions in concrete. Therefore, developing a heavy metal ion leaching testing method suitable for cement concrete is of significant practical importance. Summary of the Invention

[0005] To improve the accuracy of heavy metal ion leaching detection in gold tailings concrete, this application provides a method and apparatus for heavy metal leaching detection in gold tailings concrete.

[0006] Firstly, this application provides a method for detecting heavy metal leaching from gold tailings concrete, employing the following technical solution: A method for detecting heavy metal leaching from gold tailings concrete, comprising the following steps: Step 1: Preparation of gold tailings concrete specimens: The specimens are hexahedral structures; Step 2: Collect the permeate from the specimen obtained in Step 1. Take the three adjacent sides of the specimen located at the same corner as the permeation surface and the other three sides as the water injection and pressurization surface. Use the anti-permeability penetration method to make the permeate flow out of the permeation surface of the specimen. Keep the inclination angle of the three permeation surfaces consistent and continuously collect the permeate flowing out of the three sides of the specimen. Step 3: Prepare the test solution: Collect samples of the permeate at regular intervals, mix the samples from the three sides evenly, and then dilute to obtain the test solution; Step 4: Detect the concentration of heavy metal ions in each prepared test solution until the concentration of heavy metal ions in the test solution is zero, then stop collecting the permeate. Step 5: Mix all the collected permeate thoroughly to obtain a mixed solution. Detect the concentration of heavy metal ions in the mixed solution and calculate the heavy metal leaching amount M per unit volume of concrete using the following formula: M = CV1 / V2, where M is the heavy metal leaching amount in mg / m³. 2 C - Concentration of heavy metal ions in the mixture (mg / L), V1 - Volume of the mixture (L), V2 - Volume of the specimen (m). 2 .

[0007] By adopting the above technical solution, this application prepares standard test blocks of gold tailings concrete to simulate the structural morphology of concrete after hydration and solidification, and conducts leaching tests. In existing heavy metal leaching tests, in order to quickly obtain the leaching results of heavy metal ions, most specimens are crushed or ground to increase the leaching capacity, as this can increase the surface area of ​​the sample in contact with the solvent. However, this practice will change the structure of cement hydration products, leading to the disintegration of physical and chemical bonds. At the same time, the metal tools used for crushing will also contaminate the sample. Therefore, by ensuring the structural integrity of the concrete after solidification and testing the leaching of heavy metals, the leaching situation of heavy metals in concrete can be accurately reflected. By using a hexahedral structural specimen and collecting exudate from three faces simultaneously, the solvent can seep out from as many directions as possible, increasing the flow area of ​​the solvent within the concrete structure and thus improving the accuracy of the test. Furthermore, by controlling the inclination angle of the several seepage faces consistently, the resistance to seepage of the exudate on different faces can be kept as consistent as possible, reducing external influencing factors and further improving the accuracy of the test. Expanding the seepage area can also effectively improve the testing efficiency. Finally, by detecting the concentration of heavy metal ions in the obtained exudate, the amount of heavy metals leached from the concrete can be calculated, thus better reflecting the heavy metal leaching situation of the concrete in actual conditions.

[0008] Optionally, when the specimen is first injected with water and pressurized, if no permeate seeps out from at least one side after the sampling interval has elapsed, then an identical specimen should be used to collect permeate.

[0009] By adopting the above technical solution, since the concrete structure will vary during the specimen preparation process, when the exudate seeps out on all the seepage surfaces within a short interval, the leaching efficiency of heavy metals can be effectively accelerated, thereby effectively shortening the detection cycle and improving the detection efficiency.

[0010] Optionally, the sampling interval in step three is 2-3 hours, and the sample collection time is 2-5 minutes.

[0011] By adopting the above technical solution, although a short sampling interval can efficiently determine the time period for the complete dissolution of heavy metal ions, it will significantly increase the sampling frequency, resulting in a large sample volume and affecting the final detection result. When the sampling interval is long, although the sampling frequency will be reduced to improve the detection result and detection accuracy, it is not accurate enough to determine the time period for the complete dissolution of heavy metal ions, affecting the detection efficiency. Therefore, by controlling the collection time of the sample and the collection time of the sample solution, both detection accuracy and high detection efficiency can be guaranteed.

[0012] Optionally, when injecting water and pressurizing the specimen, the water pressure should be adjusted to be maintained at 1-1.2 MPa.

[0013] By adopting the above technical solution and controlling the water pressure of the injected water to maintain it within the above range, the stability of the test can be guaranteed while effectively improving the solvent seepage efficiency, and excessive water pressure can be avoided to prevent leakage and affect the accuracy of the test results.

[0014] Secondly, this application provides a heavy metal leaching device for gold tailings concrete, which adopts the following technical solution: A heavy metal leaching device for gold tailings concrete includes an anti-seepage body and a specimen fixing assembly. The specimen fixing assembly includes a base and a mold base. The base is fixed to the outlet at the top of the anti-seepage body, and the mold base is detachably fixed to the top of the base. A specimen cavity matching a regular hexahedral specimen is formed between the base and the mold base. The bottom of the specimen cavity communicates with the outlet. A seepage port for permeate seepage is opened at the top of the mold base. The seepage port and the three adjacent faces of the specimen located at the same corner are arranged one-to-one. A guide groove is provided at the bottom of the seepage port. The anti-seepage body is used to inject water into the specimen cavity through the outlet.

[0015] By adopting the above technical solution, when heavy metal leaching testing is required on concrete specimens, a regular hexahedral concrete specimen matching the base and mold is first prepared. After removing the mold from the base, the concrete specimen is placed on the base with one corner facing down. Then, the concrete specimen is fixed between the base and the mold by fixing the mold to ensure the sealing of the contact surfaces between the specimen and the base and the mold. Finally, a water injection and pressurization test is conducted using an impermeable body. The permeate seeping from the seepage surface of the specimen is collected through a diversion channel for later use, effectively improving the permeation efficiency of heavy metal leaching from the concrete specimen, thereby improving the detection efficiency. The test results are finally determined by mixing and testing the permeate collected from the three surfaces, improving the accuracy of heavy metal leaching detection in concrete specimens.

[0016] Optionally, a gasket is provided between the base and the mold base, and a sealing sheet is provided at one end of the gasket near the cavity of the specimen, the sealing sheet being in contact with the inner wall of the base and the mold base.

[0017] By adopting the above technical solution, the sealing performance between the concrete specimen and the base and mold is further improved by setting gaskets and sealing sheets, so as to avoid leakage during pressurized water injection and thus affect the accuracy of the final test results.

[0018] Optionally, the connection between the base and the mold base is provided with a fixing protrusion, the gasket extends between the fixing protrusions, and the fixing protrusions of the base and the mold base are fixedly connected by fasteners.

[0019] By adopting the above technical solution and setting the protruding ridges, the connection between the base and the mold base is made more stable, improving the stability of the test specimen process. Furthermore, extending the gasket between the fixed protruding ridges further improves the sealing performance and prevents leakage from affecting the accuracy of the test.

[0020] Optionally, the size of the seepage opening is not less than 4 / 5 of the area of ​​one surface of the specimen.

[0021] By adopting the above technical solution and controlling the size of the seepage outlet, the influence of the mold base on the seepage of the concrete specimen can be minimized while ensuring the fixation of the specimen and the sealing of the surrounding area, thereby increasing the seepage area of ​​the specimen and improving the test efficiency.

[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. By using a hexahedral structural specimen, exudate is collected from three sides simultaneously, allowing the solvent to seep out from as many directions as possible, increasing the solvent's passage area within the concrete structure, thereby improving the accuracy of the test. Furthermore, expanding the seepage surface can effectively improve the test efficiency. 2. The leaching device includes an anti-permeability body and a specimen fixing assembly. The concrete specimen is fixed between the base and the mold, ensuring the sealing of the contact surfaces between the specimen and the base and the mold. Finally, when the anti-permeability body is used to inject water and pressurize for the permeation test, the leaching efficiency of heavy metals in the concrete specimen is effectively improved, thereby improving the detection efficiency. 3. By setting the size of the seepage port to be no less than 4 / 5 of the area of ​​one surface of the specimen, while ensuring the fixation of the specimen and the sealing of the surrounding area, the influence of the mold base on the seepage of the concrete specimen is minimized, the seepage area of ​​the specimen is expanded, and the test efficiency is improved. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a heavy metal leaching device for gold tailings concrete according to Embodiment 1 of this application.

[0024] Figure 2 yes Figure 1 An enlarged schematic diagram of part A in the middle.

[0025] Figure 3 This is a partial cross-sectional view of a heavy metal leaching device for gold tailings concrete after a concrete specimen has been fixed in it, according to Embodiment 1 of this application.

[0026] Reference numerals in the attached drawings: 1. Impermeable body; 11. Outlet; 12. Water tank; 13. Water injection pipe; 14. Workbench; 2. Specimen fixing assembly; 21. Base; 211. Mold cylinder; 212. Support base; 22. Mold base; 221. Leakage outlet; 222. Guide channel; 23. Gasket; 24. Sealing plate; 25. Fixing protrusion. Detailed Implementation

[0027] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.

[0028] Example 1 This application discloses a method for detecting heavy metal leaching from gold tailings concrete. The steps include: Step 1: Preparation of gold tailings concrete specimens: Weigh all raw materials according to the formula of the gold tailings concrete to be tested, mix and stir for 5 minutes. Prepare a cube specimen mold of the corresponding size, pour the mixed concrete into the mold and tap the mold to remove air bubbles. Level the concrete surface on the top of the mold and remove excess concrete. Mark the specimen identification information and cover it with a damp cloth for 28 days to obtain the concrete specimen. Step 2: Collect the permeate from the concrete specimens obtained in Step 1. Use the heavy metal leaching device for gold tailings concrete disclosed in this embodiment. Use three adjacent faces of the specimen located at the same corner as the permeation faces, and the other three faces as the water injection and pressurization faces. Maintain the water pressure at 1.2 MPa. Use the anti-seepage penetration method to make permeate flow out of the permeation faces of the specimens. Keep the inclination angle of the three permeation faces consistent. Continuously collect the permeate flowing out of the specimens from the three faces. When the specimens are first injected with water and pressurized, if no permeate seeps out from at least one face after more than 2 hours, replace the specimen with an identical specimen for permeate collection.

[0029] Step 3: Preparation of test solution: Collect a sample of the permeate every 2 hours for 2 minutes. Mix the samples from the three sides thoroughly and dilute 10 times to obtain the test solution. Store the diluted test solution in the refrigerator. Step 4: The concentration of heavy metal ions in each prepared test solution is detected using inductively coupled plasma optical emission spectrometry (ICP) until the concentration of heavy metal ions in the last test solution is zero, at which point the collection of permeate is stopped. Step 5: Mix all collected permeate thoroughly to obtain a mixture. Detect the concentration of heavy metal ions in the mixture using inductively coupled plasma optical emission spectrometry (ICP). Calculate the heavy metal leaching amount M per unit volume of concrete using the following formula: M = CV1 / V2, where M represents the heavy metal leaching amount in mg / m³. 2 C - Concentration of heavy metal ions in the mixture (mg / L), V1 - Volume of the mixture (L), V2 - Volume of the specimen (m). 2 .

[0030] In this embodiment, the toxicity standard for the heavy metal concentration limit is selected from toxic heavy metals that are harmful to human health, such as Cd, Cr, Cu, Mn, Ni, and Pb. The concentration of heavy metal ions in the leachate is detected according to Appendix B "Determination of Elements in Solid Waste by Inductively Coupled Plasma Mass Spectrometry" in the "Identification Standard for Hazardous Waste Leaching Toxicity Identification" (GB5085.3-2007).

[0031] This application also discloses a heavy metal leaching device for gold tailings concrete, as described in the embodiments below. Figure 1 and Figure 2The device includes an anti-permeability body 1 and a specimen fixing assembly 2. The specimen fixing assembly 2 includes a base 21 and a mold base 22. The base 21 is fixed at the outlet 11 at the top of the anti-permeability body 1. A specimen cavity matching a regular hexahedral specimen is formed between the base 21 and the mold base 22. The bottom of the specimen cavity communicates with the outlet 11. The top of the mold base 22 is provided with a seepage port 221 for the permeate to seep out. The size of the seepage port 221 is not less than 4 / 5 of the area of ​​one surface of the specimen. In this application, the size of the seepage port 221 is 4 / 5 of the area of ​​one surface of the specimen. The seepage port 221 and the three adjacent surfaces of the specimen located at the same corner are arranged one-to-one. The bottom of the seepage port 221 is provided with a guide groove 222. When the specimen is subjected to a permeation leaching test, the permeate flows out through the guide groove 222 for collection. The base 21 consists of a mold cylinder 211 and a support base 212. The mold cylinder 211 is fixed to the outlet 11 at the top of the anti-seepage body 1 by bolts. The support base 212 is integrally connected to the top of the mold cylinder 211. The support base 212 is enclosed between the four sides of the mold cylinder 211 and the side wall of the mold cylinder 211. The support base 212 and the mold base 22 cooperate to form a regular hexahedral frame to fix the concrete specimen. The mold base 22 is detachably fixed to the top of the base 21. The connection between the support base 212 and the mold base 22 is integrally provided with a fixing protrusion 25. The fixing protrusion 25 on the support base 212 and the fixing protrusion 25 on the mold base 22 are fixed by bolts.

[0032] Reference Figure 2 and Figure 3 The anti-permeability body 1 is used to inject water into the cavity of the specimen through the water outlet 11. The anti-permeability body 1 includes a workbench 14, a water tank 12, and a water injection pipe 13. Multiple water outlets 11 are distributed on the top of the workbench 14. In this application, there are six water outlets 11. Each water outlet 11 is equipped with a specimen fixing component 2. The water tank 12 is located inside the workbench 14. The water outlets 11 are the same as the interior of the water tank 12. One end of the water injection pipe 13 is connected to the bottom of the water tank 12, and the other end is connected to the water source. After the specimen is fixed by the specimen fixing component 2, water is injected into the water tank 12 by a pressure pump. The water in the water tank 12 is injected into the cavity of the specimen through the water outlet 11, thereby conducting a permeability test on the concrete specimen.

[0033] Reference Figure 2 and Figure 3 A gasket 23 is provided between the base 21 and the mold base 22. A sealing sheet 24 is provided at one end of the gasket 23 near the specimen cavity. The sealing sheet 24 fits against the inner wall of the base 21 and the mold base 22. After the specimen is fixed, the sealing sheet 24 seals the contact surfaces of the base 21, the mold base 22, and the specimen to prevent leakage during the penetration and leaching test. The gasket 23 extends between the fixing protrusions 25, further sealing the connection between the mold base 22 and the base 21, further improving the sealing performance of the device.

[0034] The implementation principle of the heavy metal leaching device for gold tailings concrete in this application embodiment is as follows: When it is necessary to conduct a leaching and permeation test on a concrete specimen, the specimen fixing assembly 2 is first heated to about 40 degrees Celsius. Then, the prepared specimen is fixed between the specimen fixing assembly 2. The specimen is fixed by the support base 212 and the mold base 22. When fixing the specimen, the edges of the specimen are sealed with paraffin wax. The base 21 is fixed to the workbench 14 with bolts. The pressure pump injects water into the water tank 12 through the water injection pipe 13 and controls the water pressure in the water tank 12 to be maintained at 1.2 MPa. The water in the water tank 12 enters the specimen cavity through the water outlet 11 to pressurize the surface of the specimen, so that the permeate seeps out through the seepage port 221 and flows into the guide channel 222 for collection. Finally, the collected permeate is tested, which effectively improves the detection efficiency of heavy metal leaching detection in concrete specimens.

[0035] Example 2 The difference between this embodiment and Embodiment 1 is that in step two of the detection method, if no permeate seeps out from at least one side after more than 3 hours, the same test block is replaced for permeate collection. Step three: Preparation of the test solution: Permeate is sampled every 3 hours, and the sample collection time is 5 minutes.

[0036] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for detecting heavy metal leaching from gold tailings concrete, characterized by: steps include: Step 1: Preparation of gold tailings concrete specimens: The specimens are hexahedral structures; Step 2: Collect the permeate from the specimen obtained in Step 1. Take the three adjacent sides of the specimen located at the same corner as the permeation surface and the other three sides as the water injection and pressurization surface. Use the anti-permeability penetration method to make the permeate flow out of the permeation surface of the specimen. Keep the inclination angle of the three permeation surfaces consistent and continuously collect the permeate flowing out of the three sides of the specimen. Step 3: Prepare the test solution: Collect samples of the permeate at regular intervals, mix the samples from the three sides evenly, and then dilute to obtain the test solution; Step 4: Detect the concentration of heavy metal ions in each prepared test solution until the concentration of heavy metal ions in the test solution is zero, then stop collecting the permeate. Step 5: Mix all the collected permeate thoroughly to obtain a mixed solution. Detect the concentration of heavy metal ions in the mixed solution and calculate the heavy metal leaching amount M per unit volume of concrete using the following formula: M = CV1 / V2, where M is the heavy metal leaching amount in mg / m³. 2 C - Concentration of heavy metal ions in the mixture (mg / L), V1 - Volume of the mixture (L), V2 - Volume of the specimen (m). 2 ; When the specimen is first injected with water and pressurized, if no permeate seeps out from at least one side after the sampling interval has elapsed, then replace it with an identical specimen for permeate collection.

2. The method for detecting heavy metal leaching from gold tailings concrete according to claim 1, characterized in that: In step three, the sampling interval is 2-3 hours, and the sample collection time is 2-5 minutes.

3. The method for detecting heavy metal leaching in gold tailings concrete according to claim 2, characterized in that: When injecting water and pressurizing the specimen, adjust the water pressure to maintain at 1-1.2 MPa.

4. A heavy metal leaching device for gold tailings concrete, characterized in that: The apparatus is applied to a method for detecting heavy metal leaching in gold tailings concrete as described in any one of claims 1-3. The apparatus includes an anti-permeability body (1) and a specimen fixing assembly (2). The specimen fixing assembly (2) includes a base (21) and a mold base (22). The base (21) is fixed at the outlet (11) at the top of the anti-permeability body (1). The mold base (22) is detachably fixed at the top of the base (21). A specimen cavity matching a regular hexahedral specimen is formed between the base (21) and the mold base (22). The bottom of the specimen cavity is connected to the outlet (11). A seepage port (221) for seepage of permeate is provided at the top of the mold base (22). The seepage port (221) is provided with three adjacent faces of the specimen located at the same corner. A guide groove (222) is provided at the bottom of the seepage port (221). The anti-permeability body (1) is used to inject water into the specimen cavity through the outlet (11). A gasket (23) is provided between the base (21) and the mold base (22). A sealing sheet (24) is provided at one end of the gasket (23) near the cavity of the specimen. The sealing sheet (24) is in contact with the inner wall of the base (21) and the mold base (22). The base (21) and the mold base (22) are both provided with fixed protrusions (25), and the gasket (23) extends between the fixed protrusions (25). The fixed protrusions (25) of the base (21) and the mold base (22) are fixedly connected by fasteners.

5. A heavy metal leaching device for gold tailings concrete according to claim 4, characterized in that: The size of the seepage port (221) is not less than 4 / 5 of the area of ​​one surface of the specimen.

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