Method for preparing acid soil conditioner from gold ore flotation tailings

Abstract

The invention belongs to the technical field of solid waste treatment, and particularly provides a method for preparing an acid soil conditioner by using gold ore flotation tailings, which comprises the following steps: S1, providing gold ore flotation tailing powder; s2, the gold ore flotation tailing powder is mixed with an activating agent, and mixed powder is obtained; s3, roasting and activating the mixed powder to obtain the acid soil conditioner. According to the method disclosed by the embodiment of the invention, the gold ore flotation tailings are subjected to activating treatment, so that the conditioner for adjusting the acid soil can be prepared, waste utilization and zero emission of gold ore smelting are realized, the ecological environment is not damaged, and considerable economic benefits are brought at the same time.

Description

Technical Field

[0001] This invention belongs to the field of solid waste treatment technology, and more specifically, relates to a method for preparing an acidic soil conditioner using gold ore flotation tailings. Background Technology

[0002] Gold is present in extremely low concentrations in ores. To extract gold, the ore needs to be crushed and ground, and beneficiation methods must be used to pre-enrich or separate the gold from the ore. Currently, the main beneficiation methods include gravity separation and flotation. As a product of the beneficiation process, the portion with the lowest concentration of the target component is called tailings. Under current technological and economic conditions, further beneficiation is no longer advisable.

[0003] However, tailings are not entirely useless waste; they often contain components that can be used for other purposes and can be comprehensively utilized.

[0004] Achieving zero waste discharge is necessary for the full utilization of mineral resources and the protection of the ecological environment. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for preparing an acidic soil conditioner using gold ore flotation tailings.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for preparing an acidic soil conditioner using gold ore flotation tailings according to an embodiment of the present invention includes: Step S1: Provide gold ore flotation tailings powder; Step S2: Mix the gold ore flotation tailings powder with an activator to obtain a mixed powder; Step S3: The mixed powder is calcined and activated to obtain the acidic soil conditioner.

[0007] In some embodiments of the present invention, step S1 includes: Obtain gold ore flotation tailings slag; The gold ore flotation tailings slag is pretreated to obtain the gold ore flotation tailings powder. The pretreatment includes grinding and / or sieving to make the particle size of the gold ore flotation tailings powder less than 1 mm, preferably in the range of 0.05 mm to 0.5 mm, so as to increase the specific surface area and improve the efficiency of subsequent activation reaction.

[0008] In some embodiments of the present invention, in step S2, the activator is selected from one or more of CaO, MgO, KOH, and NaOH, and the activator accounts for 25%-50% of the total weight of the mixed powder.

[0009] Furthermore, the activator is preferably a compound activator containing CaO and NaOH, wherein CaO accounts for 20% to 40% of the total weight of the mixed powder, and NaOH accounts for 2% to 10% of the total weight of the solid components in the mixed powder.

[0010] Further, step S2 includes: The gold ore flotation tailings powder is mixed and stirred with the activator and water to obtain a mixed slurry; The mixed slurry is left to stand for 12-36 hours and then dried to remove the water, thus obtaining the mixed powder.

[0011] Furthermore, in step S2, a flux is added to the mixed slurry. The flux is selected from NaF, Na2B4O7·10H2O, or a mixture thereof, and the flux accounts for 0.5%-2% of the total weight of the mixed powder.

[0012] Furthermore, the aging process is carried out at 25-80°C.

[0013] In some embodiments of the present invention, in step S3, the calcination activation temperature is 700-1200℃ and the time is 1-6 hours.

[0014] In some embodiments of the present invention, the method further includes: Step S4: Grind and granulate the calcined and activated acidic soil conditioner to obtain acidic soil conditioner granules.

[0015] Furthermore, during the granulation process, a binder is used to mix the ingredients and then extrude them into granules. The binder is selected from one or more of pregelatinized starch, bentonite, humic acid, gypsum, and sodium lignosulfonate.

[0016] The above-described technical solution of the present invention has at least one of the following beneficial effects: According to the method of the present invention, a large amount of flotation tailings can be used as an acid soil conditioner after processing to improve acid soil, thereby turning waste into treasure and eliminating waste discharge. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0018] The following describes in detail a method for preparing an acidic soil conditioner using gold ore flotation tailings according to an embodiment of the present invention.

[0019] A method for preparing an acidic soil conditioner using gold ore flotation tailings according to an embodiment of the present invention includes: Step S1: Provide gold ore flotation tailings powder; Step S2: Mix the gold ore flotation tailings powder with an activator to obtain a mixed powder; Step S3: The mixed powder is calcined and activated to obtain the acidic soil conditioner.

[0020] In other words, for gold ore flotation tailings, the gold ore flotation tailings powder is first mixed with an activator, and then roasted to activate it, resulting in an acidic soil conditioner for conditioning acidic soils. This allows for the utilization of gold ore flotation tailings, not only fully utilizing the minerals within to modify the soil to meet ecological needs, but also eliminating the need for slag filling and other treatments, generating significant economic benefits while being environmentally friendly.

[0021] The following is a detailed explanation of each of the above steps.

[0022] (i) Provide gold ore flotation tailings powder (i.e., step S1).

[0023] The method described in this application can be implemented directly in a gold flotation plant to treat the tailings from the production line, i.e., gold flotation tailings, and can also be applied to a soil conditioner preparation plant to process incoming materials.

[0024] According to some embodiments of the present invention, step S1 includes: Obtain gold ore flotation tailings slag; The gold ore flotation tailings slag is pretreated to obtain the gold ore flotation tailings powder. The pretreatment includes grinding and / or sieving to make the particle size of the gold ore flotation tailings powder less than 1 mm.

[0025] In other words, for gold ore flotation tailings slag, pretreatment is first carried out to align the powder through grinding and screening, thereby obtaining gold ore flotation tailings powder with a particle size of less than 1 mm. Screening out large particles larger than 1 mm helps to improve the uniformity of mixing with the activator in subsequent stages, thus enabling better uniform activation of the tailings slag powder during the roasting stage, improving the activation effect, and ultimately enhancing the uniformity and performance stability of the product.

[0026] (ii) Preparation of a mixed powder of gold ore flotation tailings powder and activator (i.e. step S2).

[0027] In other words, in this application, an activator is used to activate the silica in the tailings slag. Through the activation reaction, the original crystalline silica (ineffective silica) in the tailings is converted into amorphous, soluble silicates (effective silica), thereby increasing the silica content in the target product and acting as a silicon fertilizer while regulating soil acidity.

[0028] According to some embodiments of the present invention, the activator is selected from one or more of CaO, MgO, KOH, and NaOH, and the activator accounts for 25%-50% of the total weight of the mixed powder. The above-mentioned activator can react with silica in the tailings to form silicates during the roasting process. The silicon in the silicates is easily absorbed by crops and is therefore also called effective silicon. After roasting, it can act as a silicon fertilizer.

[0029] Furthermore, through repeated and extensive experiments, the inventors discovered that using a combination of CaO and NaOH achieves a better activation effect. CaO serves as the main alkaline component and structural modifier. At high temperatures, it reacts with SiO2 to form calcium silicate, a process that disrupts the stable crystal structure of minerals such as quartz, forming the basis for silicon activation. Simultaneously, the calcium ions provided by CaO are themselves a core effective component for improving acidic soils. NaOH melts at relatively low temperatures and, as a mineralizer and mass transfer medium, significantly reduces the activation energy of the system, promoting the kinetics of solid-phase reactions. More importantly, NaOH preferentially reacts with the more reactive aluminosilicate components (such as feldspar) in tailings to generate soluble sodium aluminate and other intermediate products, "opening up" the mineral structure and paving the way for the full reaction between CaO and internal SiO2. This "double-pronged, point-to-surface" activation path produces a synergistic activation effect of "1+1>2," enabling the originally stable silicon element to be converted in large quantities and efficiently into a form with high soil chemical activity.

[0030] Specifically, when CaO and NaOH account for 30%~40% and 2%~5% of the total weight of solid components in the mixed slurry, respectively, an effective silicon activation rate of 25%~40% can be obtained; when CaO and NaOH account for 20%~30% and 5%~10% of the total weight of solid components in the mixed slurry, respectively, an effective silicon activation rate of 40%~60% can be obtained.

[0031] Furthermore, the inventors have discovered that allowing the mixture to stand and age after mixing significantly promotes the activation of silica in the tailings.

[0032] The aging process is a crucial "chemical pre-activation" or "induction reaction" stage. Its core principle lies in: Ion penetration and migration: Under the medium of water, OH- ions dissociate from a strongly alkaline activator. -Ions and Ca²⁺ ions can penetrate into the micropores, cracks, and crystal defects of tailings particles, laying the foundation for subsequent bulk phase reactions.

[0033] Preferred corrosion and activation of the surface: OH - The ions will undergo a low-temperature hydrothermal reaction with the silica and silicate minerals on the surface of the tailings particles, partially dissolving the silicon-oxygen network and generating reactive silicate ion precursors.

[0034] The formation of new phases and stress generation: The newly formed silicate and aluminate gels produced by the reaction differ in size and structure from the original minerals, generating micro-stress within the particles. This stress helps to generate more microcracks within the particles, greatly increasing the specific surface area and providing more channels for the further intrusion of activators during high-temperature calcination.

[0035] Homogenization of components: The aging process makes the moisture and activator more evenly distributed, avoiding local overheating or uneven reaction during subsequent drying and roasting processes, and ensuring the uniformity of the chemical composition of the final product.

[0036] Specifically, in some embodiments of the present invention, step S2 includes: The gold ore flotation tailings powder is mixed and stirred with the activator and water to obtain a mixed slurry; The mixed slurry is left to stand for 12-36 hours and then dried to remove the water, thus obtaining the mixed powder.

[0037] Preferably, aging is carried out at 25-80℃.

[0038] After aging, the material undergoes some chemical reactions before entering the most energy-intensive roasting process, which disrupts the stable surface structure of the minerals. Therefore, the temperature and holding time required to achieve the same level of activation during subsequent roasting can be significantly reduced, achieving energy conservation and consumption reduction. The aging process weakens the stability of the mineral lattice beforehand, making the main reaction at high temperatures more thorough and rapid. The effective silicon content in the final product of aged samples is 5%-10% higher than that of unaged samples.

[0039] In addition, methods such as sun-drying or low-temperature drying can be used to remove moisture and accelerate the activation process.

[0040] In addition, in order to lower the roasting temperature so that the activator and tailings powder can undergo an activation reaction at a lower temperature, an appropriate co-solvent can be added to the mixed powder.

[0041] Specifically, in some embodiments of the present invention, a flux is also added to the mixed slurry. The flux is selected from NaF, Na2B4O7·10H2O, or a mixture thereof, and the flux accounts for 0.5%-2% of the total weight of the mixed powder. Among them, NaF has a more significant promoting effect on tailings activation. NaF has a unique "etching" effect. At high temperatures, F... - With its small ionic radius and extremely high electronegativity, NaF possesses exceptional penetrating and destructive capabilities. It can directly attack the silicon-oxygen bonds of SiO2, reacting to form gaseous SiF4 that escapes, or creating defects in the crystal lattice. This action is akin to "micro-etching" the surface and interior of a robust quartz crystal, generating numerous pores and cracks, providing unprecedented pathways for the activator's intrusion. Furthermore, NaF can induce crystal transformation, generating the active phase. - Ions, as a highly efficient mineralizing agent, can significantly reduce the temperature at which quartz transforms from the α-type to the β-type and induce the formation of active silicate minerals such as wollastonite, which are easily dissolved by acids. This alters the thermodynamic and kinetic pathways of the reaction, guiding the system toward the formation of highly active products.

[0042] (iii) Calcination and activation (i.e. step S3).

[0043] In other words, after mixing the tailings slag powder with the activator, it needs to be roasted at a high temperature so that the activator reacts with the silica in the tailings slag powder to generate silicates, thereby converting silicon into usable silicon fertilizer.

[0044] In some embodiments of the present invention, in step S3, the calcination activation temperature is 700-1200°C and the time is 1-6 hours. Higher calcination temperatures and longer calcination times have limited effect on further improving activation efficiency and will increase costs. Preferably, the calcination temperature is 800-900°C and the calcination time is 2 hours.

[0045] After obtaining the acidic soil conditioner, it can be further granulated. Specifically, according to some embodiments of the present invention, the method further includes: Step S4: Grind and granulate the calcined and activated acidic soil conditioner to obtain acidic soil conditioner granules.

[0046] Among these processes, grinding can make the particle size more uniform, while granulation can make the particles stronger, making them easier to transport and use.

[0047] Furthermore, as a granulation process, a binder can be mixed with a calcined and activated acidic soil conditioner, followed by extrusion granulation. The binder can be one or more of pregelatinized starch, bentonite, humic acid, gypsum, and sodium lignosulfonate. Humic acid granules have slightly lower particle strength but shorter disintegration times; granules with other binders have higher particle strength but longer disintegration times. Bentonite is preferred, as it produces granules with high strength and an acceptable disintegration time of 55 minutes.

[0048] The method for preparing acidic soil conditioner from gold ore flotation tailings according to the present invention will be further described in detail below through specific embodiments.

[0049] The tailings slag used in the following examples came from Kunyu tailings. The initial particle size P80 of Kunyu tailings was 152 μm (100 mesh). The multi-element analysis results of the sample are shown in Table 1. The main components of the tailings were SiO2 and Al2O3, and it also contained a small amount of K2O, Fe2O3 and CaO. Moreover, the content of the main heavy metals was found to be lower than the standard limit of the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB 15618-2018), indicating good environmental safety performance.

[0050]

[0051] It should be noted that this is a simplified example of tailings; however, the method of the present invention is not limited to this tailings and can be applied to flotation tailings tailings from different gold mines.

[0052] To systematically verify the effects of different activator systems, fluxes, and process conditions on the effective silicon content in the product, multiple samples were prepared according to the composition and activation conditions listed in Table 2 below, and the effective silicon content (calculated as SiO2) was measured. The results are summarized in Table 2. To illustrate the effects of activators and fluxes, Table 2 also lists comparative examples prepared from tailings powder without activators or fluxes under the same calcination conditions.

[0053]

[0054] By comparing the data of each embodiment and comparative example in Table 2, firstly, compared with Comparative Example 1 which was only calcined without the addition of an activator, the effective silicon content of all embodiments with the addition of an alkaline activator was significantly improved. This fully demonstrates that chemical activation is the core means of unlocking inert silicon in tailings. Secondly, the combination of CaO and NaOH exhibits a significant synergistic effect. The effective silicon content of Example 4 is as high as 25.83%, which is much higher than that of CaO alone (Example 1) and also significantly higher than that of NaOH alone (Example 3). This verifies the synergistic mechanism of "CaO constructs the framework, and NaOH promotes mass transfer" described in this invention. Thirdly, the addition of 2% NaF to the single CaO system (Example 1) (Example 6) increased the effective silicon content from 15.42% to 22.18%, proving the effectiveness of using flux alone. More importantly, the introduction of 2% NaF into the optimal compound activator system (30% CaO + 5% NaOH) forms a "synergistic superposition effect". As shown in Example 7, the effective silicon content jumped from 25.83% in Example 4 to 31.25%, reaching the highest value in this series of experiments. This fully demonstrates that the core technical advantage of this invention is the combination of "compound activator + high-efficiency flux". The use of borax as a flux (Example 9) also showed good results (29.76%), but slightly inferior to NaF, confirming the superior performance of NaF as a flux.

[0055] In summary, this invention provides a method for preparing an acidic soil conditioner using gold ore flotation tailings. By optimizing the activator system of CaO and NaOH and innovatively introducing fluxes such as NaF, a multi-component synergistic and highly efficient activation pathway is constructed. This method can efficiently convert a large amount of originally ineffective crystalline silicon in the tailings into usable silicon that can be absorbed by plants under relatively mild process conditions, significantly improving the conversion rate and successfully achieving high-value-added resource utilization of waste residue. It also offers advantages in energy-saving and consumption-reducing industrial applications.

[0056] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an acidic soil conditioner using gold ore flotation tailings, characterized in that, include: Step S1: Provide gold ore flotation tailings powder; Step S2: Mix the gold ore flotation tailings powder with an activator to obtain a mixed powder; Step S3: The mixed powder is calcined and activated to obtain the acidic soil conditioner.

2. The method according to claim 1, characterized in that, Step S1 includes: Obtain gold ore flotation tailings slag; The gold ore flotation tailings slag is pretreated to obtain the gold ore flotation tailings powder. The pretreatment includes grinding and / or sieving to make the particle size of the gold ore flotation tailings powder less than 1 mm.

3. The method according to claim 1, characterized in that, In step S2, the activator is selected from one or more of CaO, MgO, KOH, and NaOH, and the activator accounts for 25%-50% of the total weight of the mixed powder.

4. The method according to claim 3, characterized in that, The activator is a compound activator containing CaO and NaOH, wherein CaO accounts for 20% to 40% of the total weight of the mixed powder, and NaOH accounts for 2% to 15% of the total weight of the solid components in the mixed powder.

5. The method according to claim 1, characterized in that, Step S2 includes: The gold ore flotation tailings powder is mixed and stirred with the activator and water to obtain a mixed slurry; The mixed slurry is left to stand for 12-36 hours and then dried to remove the water, thus obtaining the mixed powder.

6. The method according to claim 5, characterized in that, In step S2, a flux is added to the mixed slurry. The flux is selected from NaF, Na2B4O7·10H2O, or a mixture thereof, and the flux accounts for 0.5%-2% of the total weight of the mixed powder.

7. The method according to claim 5, characterized in that, The aging process is carried out at 25-80°C.

8. The method according to claim 1, characterized in that, In step S3, the calcination activation temperature is 700-1200℃, and the time is 1-6 hours.

9. The method according to claim 1, characterized in that, Also includes: Step S4: Grind and granulate the calcined and activated acidic soil conditioner to obtain acidic soil conditioner granules.

10. The method according to claim 9, characterized in that, During the granulation process, a binder is used to mix the ingredients and then extrude them into granules. The binder is selected from one or more of pregelatinized starch, bentonite, humic acid, gypsum, and sodium lignosulfonate.

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