Low-grade uranium-gold polymetallic ore tailing solidification method

Abstract

The invention discloses a low-grade uranium-gold polymetallic ore tailing solidification method. The method comprises the steps that S1, uranium tailing pretreatment is conducted, specifically, uranium tailings are screened and ground; s2, a curing additive is prepared, wherein uranium tailings, metakaolin, sodium hydroxide and a water reducing agent are prepared into mixed slurry according to the proportion of 100: 27: 54: 1; preparing a calcium chloride solution with the mass fraction of 15-25%; s3, curing is carried out, specifically, a peristaltic pump is adopted to sequentially inject the calcium chloride solution and the mixed slurry into the uranium tailings in the curing reaction container at a constant speed; and S4, curing and curing, wherein the curing reaction container subjected to grouting is subjected to standing and curing. According to the method, the pore structure of the uranium tailing solidified body is effectively improved, and the bonding strength among particles is enhanced. A gel network generated by alkali excitation reaction generates a chemical fixation effect on heavy metal ions, and meanwhile, the compressive strength and the penetration resistance of a solidified body are improved. The grouting process is accurately controlled, so that the consistency of the quality of a solidified body is guaranteed, and the common problem of weak local strength in a traditional method is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of uranium tailings treatment, in particular to a method for solidifying low-grade uranium-gold polymetallic ore tailings. Background Art

[0002] Uranium, a vital strategic resource for the nuclear industry, produces large quantities of uranium tailings during its mining process. These tailings are not only bulky and occupy vast areas, but are also radioactive and contain significant quantities of heavy metals and other hazardous substances. Due to their loose particles, uneven particle size, and poor integrity, uranium tailings are prone to radionuclides release and migration. Furthermore, their high porosity and poor cohesiveness make them a serious environmental threat if not properly handled.

[0003] Currently, cement and fly ash are the primary materials used to solidify uranium tailings. However, cement production is energy-intensive and highly polluting, and long-term exposure to acidic uranium tailings can lead to carbonization and reduced strength. While fly ash has a certain solidification effect, its active ingredient content is relatively low, and its glassy structure is dense, making it difficult to fully exert its activity under alkaline stimulation. Furthermore, existing solidification technologies often rely on stirring and mixing, which makes it difficult to maintain the original structure of the tailings. Furthermore, they suffer from drawbacks such as volume expansion of the solidified material and long processing cycles.

[0004] Given the unique properties of uranium tailings, existing technologies have yet to develop a solidification method that can effectively immobilize radioactive materials and heavy metals while maintaining the tailings' original structure. In particular, for the treatment of low-grade uranium-gold and polymetallic tailings, there is an urgent need for a new, environmentally friendly, efficient, and cost-effective solidification technology. Summary of the Invention

[0005] In view of this, the present invention provides a low-grade uranium-gold polymetallic ore tailings solidification method, which has the advantages of environmental protection, high efficiency, stable solidified body structure and short processing cycle.

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for solidifying low-grade uranium-gold polymetallic ore tailings, comprising: S1, uranium tailings pretreatment: screening and grinding the uranium tailings; S2, preparing a solidification additive: preparing a mixed slurry of uranium tailings, metakaolin, sodium hydroxide, and a water reducer in a ratio of 100:27:54:1; and preparing a calcium chloride solution with a mass fraction of 15-25%; S3, implementing solidification: injecting the calcium chloride solution and the mixed slurry into the uranium tailings in a solidification reaction vessel in sequence at a constant rate using a peristaltic pump; and S4, solidification curing: static curing of the solidification reaction vessel after grouting.

[0007] Preferably, step S1 comprises: screening the uranium tailings using a screening device to determine the particle size distribution; and performing mechanical activation treatment on the uranium tailings using a ball mill to increase the specific surface area and activity.

[0008] Preferably, during grouting, a bottom-up grouting method is adopted, that is, the calcium chloride solution and the mixed slurry are both injected from the bottom of the solidification reaction container.

[0009] Preferably, a filter is provided at the grouting port at the bottom of the solidification reaction vessel to prevent fine particles of uranium ore from sinking and clogging the grouting port.

[0010] Preferably, the longer the curing time, the higher the stability and consistency of the quality of the cured body.

[0011] Preferably, the curing reaction container is a reaction container made of acrylic material.

[0012] The beneficial effects of the present invention are as follows: Compared with the prior art, the present application effectively improves the pore structure of the uranium tailings solidified body and enhances the bonding strength between particles. The sufficient penetration of the solidifying material into the tailings pores significantly reduces the connectivity of the radionuclide migration channels. The gel network generated by the alkali excitation reaction chemically fixes the heavy metal ions, while also improving the compressive strength and anti-permeability properties of the solidified body. The precise control of the grouting process ensures the consistency of the solidified body quality and avoids the localized weakness common in traditional methods.

[0013] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a flow chart of the low-grade uranium-gold polymetallic ore tailings solidification method of the present invention; Figure 2 This is a relationship diagram between the radon release rate on a single surface of each sample after solidification of the uranium tailings of the present invention and the mass fraction of calcium chloride; Figure 3 This is a graph showing the strength of the solidified body of the present invention when the confining pressure is 300 kPa and the curing time is 3 days; Figure 4 This is a graph showing the strength of the solidified body of the present invention when the confining pressure is 300 kPa and the curing time is 7 days; Figure 5 The figure is a relationship diagram between the uranium leaching concentration and the mass fraction of calcium chloride after the uranium tailings are solidified. DETAILED DESCRIPTION

[0015] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0016] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0017] The following describes a method for solidifying low-grade uranium-gold polymetallic ore tailings in an embodiment of the present invention.

[0018] The present application discloses a method for solidifying low-grade uranium-gold polymetallic ore tailings, comprising: S1, uranium tailings pretreatment: screening and grinding the uranium tailings; S2, preparing a solidification additive: preparing a mixed slurry of uranium tailings, metakaolin, sodium hydroxide, and a water reducer in a ratio of 100:27:54:1; and preparing a calcium chloride solution with a mass fraction of 15-25%; S3, implementing solidification: injecting the calcium chloride solution and the mixed slurry into the uranium tailings in a solidification reaction vessel in sequence at a constant rate using a peristaltic pump; and S4, solidification curing: static curing of the solidification reaction vessel after grouting.

[0019] Specifically, the screening process separates the tailings into different particle size groups, forming a reasonable grading curve, and providing uniform pore channels for subsequent grouting. The grinding process breaks the inert layer on the surface of the tailings particles, exposing fresh active surfaces and enhancing the reaction activity with the curing agent. The metakaolin in the mixed slurry provides active silica-alumina components, sodium hydroxide acts as an alkaline activator to dissolve the silica-alumina phase, and the water reducer improves the fluidity of the slurry. After the calcium chloride solution is injected as a calcium source, it reacts with the aluminosilicate in the slurry to form a gelling material. The constant grouting rate of the peristaltic pump allows the solution to gradually penetrate along the pores of the tailings, avoiding local blockages or the formation of unreacted areas. During the curing stage, the gel network continues to grow, filling the pores and wrapping the tailings particles to form a dense solidified body.

[0020] Preferably, for example Figure 2 As shown in the figure, when the mass ratio of uranium tailings, metakaolin, sodium hydroxide and water reducer is 100:27:54:1 and a calcium chloride solution with a mass fraction of 20% is injected, the solidification effect is better, the triaxial test strength reaches the maximum, the uranium leaching rate decreases by 82.6%, and the radon extrusion rate decreases by 57.2%.

[0021] Compared with existing technologies, this method solves the problem of uneven material distribution in loose tailings by optimizing the material injection method instead of the traditional mixing process. The constant rate grouting process is more conducive to the gradual filling of pores and avoids the formation of air pockets compared to intermittent grouting. The specifically proportioned mixed slurry and calcium source solution work synergistically to form a more stable gel structure than a single curing agent system. The bottom-up grouting path design overcomes the material stratification caused by gravity settling and ensures uniform vertical distribution of the curing agent.

[0022] Through the above-mentioned technical solution, the present application effectively improves the pore structure of the uranium tailings solidified body and enhances the bonding strength between particles. The sufficient penetration of the solidifying material into the tailings pores significantly reduces the connectivity of the radionuclide migration channels. The gel network generated by the alkali-induced reaction chemically fixes the heavy metal ions, while also improving the compressive strength and anti-permeability properties of the solidified body. Precise control of the grouting process ensures the consistency of the solidified body quality and avoids the localized weakness common in traditional methods.

[0023] Furthermore, step S1 includes: using a screening device to screen the uranium tailings to determine the particle gradation; using a ball mill to perform mechanical activation treatment on the uranium tailings to increase the specific surface area and activity. Specifically, the uranium tailings are first subjected to a screening device to achieve particle size classification, and the material is divided into three components: coarse particles, medium particles and fine particles by controlling the mesh size of the screen. After measuring the proportion of each component, the components are remixed to form a standard gradation. The mixed material is then continuously ground using a ball mill. During the grinding process, mechanical energy is converted into surface energy, which increases the number of hydroxyl groups on the particle surface and generates a new nanoscale surface, which significantly improves the reaction activity of the material with the alkaline curing agent.

[0024] By carrying out the above steps, the packing density of the uranium tailings particles can be effectively improved, so that the solidified material can evenly penetrate into the pore structure; at the same time, the interface bonding strength between the tailings particles and the cementitious material is enhanced through surface activation treatment, forming a continuous three-dimensional network structure, thereby reducing the risk of radioactive nuclide migration and improving the overall stability of the solidified body.

[0025] In some embodiments, during grouting, a bottom-up grouting method is adopted, that is, the calcium chloride solution and the mixed slurry are injected from the bottom of the solidification reaction vessel. Specifically, after the slurry enters from the bottom, it diffuses upward in the vertical direction, and contacts and penetrates with the uranium tailings particles during the flow. The slurry forms a laminar flow state in the pores, avoiding local turbulence that causes uneven distribution of materials. This flow mode allows the slurry to gradually infiltrate the uranium tailings layer, ensuring that the solidified material is evenly diffused in three-dimensional space. The upward driving force generated by the bottom injection can drive the fine particles to suspend and reduce their deposition and accumulation near the grouting port. This method avoids the damage to the original structure of the uranium tailings by mechanical stirring and maintains the integrity of the solidified body.

[0026] Through the above-mentioned technical solution, this application achieves uniform penetration and distribution of the solidifying material within the uranium tailings, ensuring full contact between the reactants. The slurry flow process maintains the original pore structure of the uranium tailings, forming a continuous and dense cementing network. The bottom injection method significantly reduces the probability of grouting pipeline blockage, ensuring continuous and stable operation of the solidification process.

[0027] Furthermore, a filter is installed at the grouting port at the bottom of the solidification reaction vessel to prevent fine uranium ore particles from sinking and clogging the port. The filter is a physical barrier with a porous structure, specifically a multi-layer stainless steel mesh or ceramic filter element, which intercepts sinking fine particles while allowing the slurry to pass through.

[0028] Specifically, when the calcium chloride solution and mixed slurry are injected via a peristaltic pump, fine particles in the uranium tailings naturally settle under the action of gravity. The filter element acts as the first barrier, retaining particles larger than the pore size through its porous structure while allowing liquid components and fine particles to pass through. This device forms a dynamic filtration layer within the slurry flow path, preventing large particles from entering the grouting port and causing mechanical blockage while maintaining a stable slurry flow rate. The filter element's removable design facilitates regular cleaning of retained particles, ensuring the long-term reliability of the grouting system.

[0029] Through the above technical solution, the present application effectively avoids the problem of pipeline blockage caused by particle deposition during the grouting process, ensures the uniform penetration and sufficient reaction of the solidification material in the uranium tailings, significantly improves the continuity and stability of the solidification process, and reduces the equipment maintenance frequency and operating costs.

[0030] In this application, for example Figure 3 and Figure 4 As shown, by observing the curing time-solidified body strength graph, it can be concluded that the longer the curing time, the higher the stability and consistency of the solidified body quality.

[0031] Preferably, taking into account factors such as curing efficiency, curing strength and curing cycle, a curing time of 28 days is selected as appropriate, at which time the overall cured body has a better performance state.

[0032] In some embodiments, the curing reaction container is a reaction container made of acrylic material. Specifically, during the grouting process, the acrylic container forms a physical isolation layer with the alkaline components in the mixed slurry through its chemically inert surface, preventing the sodium hydroxide solution from corroding the container wall. During the curing reaction stage, the hydrophobic properties of the inner wall of the container reduce the probability of slurry adhesion and ensure uniform expansion of the reaction interface. During the curing process, the high-temperature stability of the material maintains the geometric integrity of the container under long-term static conditions, avoiding seal failure due to thermal expansion and contraction. The transparent property allows operators to directly observe the slurry penetration depth and gel formation state, and adjust the grouting parameters in a timely manner.

[0033] The reaction vessel made of acrylic material can effectively prevent corrosion and deterioration of the container during the curing reaction, ensuring the long-term stability of the grouting process. At the same time, it realizes the visual control of the reaction process, provides a direct observation method for optimizing the grouting parameters, and significantly improves the repeatability and reliability of the curing process.

[0034] Other components and operations of the low-grade uranium-gold polymetallic ore tailings solidification method according to the embodiment of the present invention are well known to those skilled in the art and will not be described in detail here.

[0035] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0036] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for solidifying low-grade uranium-gold polymetallic ore tailings, characterized in that: include: S1. Uranium tailings pretreatment: screening and grinding of uranium tailings; S2. Prepare a solidification additive: prepare a mixed slurry of uranium tailings, metakaolin, sodium hydroxide, and water reducer in a ratio of 100:27:54:1; and prepare a calcium chloride solution with a mass fraction of 15-25%; S3, implementing solidification: using a peristaltic pump to inject the calcium chloride solution and the mixed slurry into the uranium tailings in the solidification reaction container in sequence at a constant rate; S4. Solidification and curing: The solidification reaction vessel after grouting is placed in a static state for curing.

2. The method for solidifying low-grade uranium-gold polymetallic ore tailings according to claim 1, characterized in that: Step S1 includes: using a screening device to screen the uranium tailings to determine the particle size distribution; and using a ball mill to perform mechanical activation treatment on the uranium tailings to increase the specific surface area and activity.

3. The method for solidifying low-grade uranium-gold polymetallic ore tailings according to claim 1, characterized in that: During grouting, a bottom-up grouting method is adopted, that is, the calcium chloride solution and the mixed slurry are injected from the bottom of the solidification reaction container.

4. The method for solidifying low-grade uranium-gold polymetallic ore tailings according to claim 2, characterized in that: A filter is provided at the grouting port at the bottom of the solidification reaction vessel to prevent fine particles of uranium ore from sinking and clogging the grouting port.

5. The method for solidifying low-grade uranium-gold polymetallic ore tailings according to claim 1, characterized in that: The longer the curing time, the higher the stability and consistency of the cured body quality.

6. The method for solidifying low-grade uranium-gold polymetallic ore tailings according to claim 1, characterized in that: The curing reaction container is a reaction container made of acrylic material.

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