Resourceful treatment method for bauxite ore washing tailing mud reservoir

Abstract

The invention relates to a resourceful treatment method for a bauxite ore washing tail mud reservoir, which comprises the following specific steps: 1, carrying out cyclone classification on tail mud in the tail mud reservoir, and separating out coarse particles with A / S greater than or equal to Y and A / Slt; and Y fine particles. And 2, carrying out flotation treatment on the coarse particles. And potassium carbonate is added as a dispersing agent and a pH value adjusting agent, the pH value of the ore pulp is adjusted to 8.0-10.5, then sodium oleate is added as a collecting agent, and finally bauxite concentrate and flotation tailings are obtained. And 3, dehydrating the fine particles to obtain dehydrated tail mud with the water content of less than or equal to 20%. And 4, adding the flotation tailings and the dehydrated tail mud into a curing agent or a soil conditioner to form cultivable soil which is used for ecological restoration of the stony desertification area. Potassium carbonate is used for replacing sodium carbonate to reinforce flotation, so that tailings can be used as potassium-rich cultivation soil; the dam break risk can be eliminated after the tail mud is dehydrated; tailings and fine particles are compounded to form cultivation soil to treat stony desertification, silicon fertilizer is synchronously produced, the annual income is larger than or equal to 0.3 million yuan, and safe, resource and ecological cooperative treatment is achieved.

Description

Technical Field

[0001] This invention relates to the field of bauxite tailings pond management technology, specifically to a resource-based management method based on potassium carbonate flotation and synergistic soil improvement. Background Technology

[0002] A bauxite tailings pond is a storage site for tailings generated during bauxite mining and washing. Both bauxite tailings ponds and bauxite tailings originate from the bauxite washing process. After screening and washing, bauxite lumps with a particle size ≥1mm (accounting for 35%) are recovered as clean ore. Particles with a particle size <1mm (clay, low-grade ore, accounting for 65%), if discharged into the tailings pond, become the objects of treatment in this invention. If particles with a particle size <1mm (clay, low-grade ore) directly enter the dry processing flow and are not discharged into the tailings pond, they become the objects of treatment in patent CN109107752A.

[0003] The tailings in bauxite tailings ponds are mainly composed of particles with a diameter of less than 1 mm (such as clay and unrecovered bauxite particles) and a small amount of siliceous rocks, limonite and other minerals. They have high fluidity (moisture content of about 50%) and are prone to forming unstable dam bodies after accumulation, posing a risk of dam failure.

[0004] This invention arose from the practice of managing tailings ponds in Guangxi bauxite mines.

[0005] The following reasons necessitate the remediation of bauxite tailings ponds: (1) Safety hazards Tailings reservoirs pose a risk of dam failure. Similar to water reservoir dams, long-term accumulation of tailings leads to high pressure on the dam body, which may cause dam failure in the event of flash floods or heavy rainfall, threatening surrounding residents and the ecological environment.

[0006] There is a risk of fluidity; historical tailings still have fluidity and are difficult to use directly for reclamation or landfill (the tailings ponds in Guangxi have accumulated up to 700 million tons).

[0007] (2) Resource waste and land occupation Tailings still contain recoverable bauxite (with a recovery value when A / S ≥ 1.6), and direct disposal results in resource waste. For example, if all the bauxite tailings from the Guangxi bauxite tailings pond were recovered, 282 million tons of recoverable bauxite concentrate could meet the ore demand of the existing alumina plant for 8 years.

[0008] The tailings ponds of Guangxi bauxite mines cover an area of ​​approximately 40,000 mu (about 667 hectares), rendering the land unusable for agriculture or ecological restoration. If all of them were treated, 30,000 mu (about 2,000 hectares) of arable land could be restored.

[0009] (3) Ecological damage and soil pollution Tailings accumulation areas are difficult to reclaim, resulting in uncultivable rocky desertification land. Traditional processes use sodium carbonate as a flotation dispersant, and residual sodium ions in the tailings damage the soil aggregate structure, leading to soil compaction.

[0010] The closest existing remediation technology is the dry treatment method described in patent CN109107752A, which discloses a dry treatment method for bauxite tailings. This method recovers fine-particle mineral sands through cyclone classification and vibrating screens, and the tailings are ultimately used for backfilling of mined-out areas. However, this technology has the following drawbacks: 1. Not applicable to tailings ponds: Tailings in tailings ponds have high fluidity and low A / S ratio (≤1.6), and existing dry treatment methods cannot effectively recover low-grade tailings.

[0011] 2. Unresolved soil pollution: Traditional processes use sodium carbonate as a dispersant, resulting in sodium ion residues in tailings, which damages soil structure.

[0012] 3. Single resource recycling: Only mineral sand is recycled, without combining tailings with ecological restoration, thus failing to achieve coordinated governance of "resources and environment".

[0013] Furthermore, existing technologies, including patent CN109107752A, cannot effectively and selectively separate aluminum-silicon minerals. Unseparated aluminum-silicon resources cannot be utilized, significantly reducing resource recovery rates. To partially separate aluminum-silicon minerals, large amounts of inhibitors and dispersants are required to suppress silicon minerals; however, poor selectivity leads to increased reagent dosage, high costs, and unstable effectiveness. Unseparated tailings require multiple sorting or chemical leaching processes, significantly increasing energy consumption and equipment wear. Summary of the Invention

[0014] The purpose of this invention is to address the problems in the prior art by providing a method for the resource-based treatment of bauxite washing tailings ponds. This method can effectively and selectively separate aluminum and silicon minerals in bauxite treatment, recover resources from low-grade tailings, and improve acidic soil.

[0015] To achieve the above objectives, the present invention provides a method for the resource-based treatment of bauxite washing tailings ponds, comprising the following steps: The first step is to perform hydrocyclone classification on the tailings in the tailings pond. Based on the characteristic that the aluminum-silicon ratio of relatively coarse ore particles is higher than that of fine particles, coarse particles with A / S greater than or equal to Y and fine particles with A / S less than Y are separated; 1.2≤Y≤3.0. The second step is to grind and flotate the coarse particles. During the grinding process, a dispersant is added and the pH of the slurry is adjusted to 8.0-10.5. During the flotation process, sodium oleate is added as a collector to obtain bauxite concentrate and flotation tailings. The third step: Dewater the fine particles to obtain dewatered tailings with a moisture content of ≤20%; The fourth step involves adding a solidifying agent or soil conditioner to the dewatered flotation tailings and dewatered tailings to form arable soil for ecological restoration in rocky desertification areas.

[0016] During the grinding process of the bauxite, potassium carbonate is added as a dispersant and pH adjuster; the amount of potassium carbonate added is 0.1%-0.5% of the dry weight of the flotation tailings, and the potassium carbonate in the flotation tailings is used as potassium fertilizer to improve acidic soil.

[0017] The flotation process described in the second step employs a composite flotation technique, including: For coarse particles with A / S≥Y, a single roughing, three scavenging, and one cleaning flotation process is performed, with a concentrate recovery rate ≥35%. The specific process of one coarse selection, three scans, and one fine selection includes the following continuous sub-steps: (1) Roughing: The pulp conditions in this step include a pulp concentration of 20%-35%, pH of 8.0-10.5, and sodium oleate addition of 300-1000 g / dry ton; the flotation time in this sub-step is 5-10 minutes. The initial separation process of this process initially separates bauxite concentrate with an A / S ratio ≥ 2.5 and rougher tailings with an A / S ratio ≤ 2.5. The concentrate with an A / S ratio ≥ 2.5 enters the cleaning process, while the rougher tailings with an A / S ratio ≤ 2.5 enter the first scavenging process. (2) For the first sweep, the amount of reagents added in this step is: 100-300 g / dry ton of sodium oleate; the flotation time in this step is 5-8 minutes. This step recovers residual bauxite with an A / S ratio ≥ 2.5 from the roughing tailings, which is then used as primary scavenging concentrate froth in the cleaning process. Scavenging tailings with an A / S ratio < 2.2 are then used for secondary scavenging. (3) Second sweeping, the amount of reagent added in this step is: sodium oleate added 0-300 g / dry ton; flotation time in this step: 5-8 minutes; This step recovers residual bauxite with an A / S ratio ≥ 2.5 from the primary scavenging tailings, which is then used as secondary scavenging concentrate foam to enter the cleaning process. Secondary scavenging tailings with an A / S ratio < 2.0 are then used for the third scavenging. (4) The amount of reagent added in the third sweep step is: sodium oleate 0-300 g / dry ton; the flotation time in this step is 5-8 minutes. This step recovers residual bauxite with an A / S ratio ≥ 2.5 from the secondary scavenging tailings, which is then used as flotation concentrate in the tertiary scavenging process. The tertiary scavenging tailings with an A / S ratio < 1.5 are used as flotation tailings. (5) Fine selection, the amount of reagent added in this step is: sodium oleate added 0-300 g / dry ton; the flotation time in this step is 5-8 minutes; This process involves collecting the concentrate froth from roughing, primary scavenging, secondary scavenging, and tertiary scavenging for further cleaning. Bauxite with an A / S ratio ≥ 4.5 is recovered as the final flotation concentrate. The cleaned tailings with an A / S ratio < 3.0 are returned to the roughing or primary scavenging process.

[0018] The dewatering process in the third step specifically includes sedimentation concentration dewatering and filter press dewatering. After dewatering, the moisture content of the fine particles is ≤20%. In the fourth step, the dewatered tailings are transformed into arable soil through soilification technology, with an organic matter content ≥2%.

[0019] The solidifying agent mentioned in the fourth step is lime or cement, and the amount added is 5%-10% of the dry weight of the tailings; the soil conditioner includes organic matter and silicon-calcium fertilizer, and the amount added is 3%-10% of the dry weight of the tailings.

[0020] It also includes a silicon fertilizer production step, in which the flotation tailings are used for silicon fertilizer production. Specific steps include: The flotation tailings are mixed with sodium hydroxide and roasted at 600-900℃ for 1.5-3 hours to produce sodium silicate. After neutralization and drying, it is made into granular silicon fertilizer with an effective silicon content of ≥20%.

[0021] The present invention has the following advantages: Eliminate safety hazards: reduce the risk of dam failure and stabilize the tailings reservoir.

[0022] Efficient resource recovery: recovering bauxite from low-grade tailings.

[0023] Ecological restoration: tailings are transformed into arable soil to control rocky desertification (in Guangxi, this application can restore 30,000 mu of arable land, with an economic value of 240 million yuan).

[0024] Environmentally friendly: Potassium carbonate replaces sodium carbonate, the tailings pH value is 8.5-9.0, potassium improves acidic soil, and silicon fertilizer is produced at the same time.

[0025] The treatment of bauxite tailings ponds is an inevitable requirement that balances safety, resources, and ecology. Technological innovation can achieve "turning waste into treasure" and sustainable development. Traditional technologies do not combine tailings treatment with ecological restoration; this invention proposes an integrated solution of flotation-soil conversion-silica fertilizer production.

[0026] Specifically, traditional flotation reagents are difficult to selectively separate aluminum-silicon minerals, and those skilled in the art do not know which flotation reagents can selectively separate aluminum-silicon minerals. This invention creatively proposes a technical solution using potassium carbonate instead of sodium carbonate as a dispersant in tailings flotation treatment, solving the problem of the difficulty of selectively separating aluminum-silicon minerals with traditional flotation reagents, and effectively achieving selective separation of aluminum-silicon minerals in tailings treatment.

[0027] In the existing understanding of those skilled in the art, the cost of recycling low-grade tailings is considered to outweigh the benefits, leading to a tendency to abandon them. Therefore, although patent CN109107752A can only recover particles with an A / S ratio ≥ 2.0, it has become a practical technological choice. This invention breaks through this understanding by using potassium carbonate, which is much more expensive than sodium carbonate, to replace sodium carbonate. This not only effectively and selectively separates aluminum and silicon minerals in tailings treatment, but also eliminates the need to add pH adjusters (such as NaOH) and soil conditioners (such as potash fertilizer) in subsequent soil improvement. This makes the cost of recycling low-grade tailings lower than the benefits, effectively managing bauxite washing tailings ponds and generating good environmental benefits such as land reclamation.

[0028] The specification of sodium oleate addition is intended to optimize flotation efficiency (concentrate recovery ≥ 50%) and reduce reagent waste.

[0029] The composite flotation technology in the second step has the following advantages: 1. Resource recycling rate significantly improved The full utilization of low-grade tailings is achieved through a composite flotation process consisting of one roughing, three scavenging, and one cleaning stage, which gradually lowers the recovery threshold (A / S value from 2.5→2.2→2.0→1.5). This increases the recovery rate of low-grade tailings (A / S≥1.5) discarded by traditional processes to ≥35%, breaking through the limitation of traditional processes that only recover high-grade particles (A / S≥2.0).

[0030] High-grade concentrate efficient purification: The fine-grained step further processes the froth from the roughing and scavenging concentrates to produce high-quality bauxite concentrate with an A / S ratio of ≥4.5 (meeting industrial smelting standards), significantly improving the overall concentrate recovery rate.

[0031] 2. Optimization of drug cost and energy consumption Gradual reduction design of reagents: The dosage of sodium oleate is gradually reduced from 300-1000 g / dry ton in the roughing process to 0-300 g / dry ton in the scavenging process, which reduces the total reagent cost by 15%-20% and avoids excessive consumption.

[0032] Flotation time is controlled in stages: roughing (5–10 minutes) → scavenging (5–8 minutes) → cleaning (5–8 minutes), reducing ineffective flotation time and lowering unit energy consumption by 10%–15%.

[0033] Optimization of reagent selectivity: By supplementing reagents during the scavenging stage (sodium oleate 0–300 g / dry ton), residual bauxite is accurately recovered, reducing reagent waste.

[0034] 3. Synergy in ecological restoration The final tailings (A / S < 1.5) are mixed with dehydrated fine particles to form topsoil (organic matter ≥ 2%, pH 6.5–7.5), which is directly used for the restoration of rocky desertification areas, with an annual treatment area of ​​≥ 30,000 mu.

[0035] Potassium carbonate, a flotation dispersant, remains in the tailings and can be used as a natural potassium fertilizer to improve acidic soils, reducing the cost of purchasing external fertilizers.

[0036] 4. Process stability and safety The tailings fluidity is eliminated, and the fine particles are dehydrated to a moisture content of ≤20% (in practice, it can be less than 10%), completely eliminating the risk of dam failure (traditional tailings moisture content ≥50%).

[0037] In terms of heavy metal pollution control, the tailings material was originally obtained from farmland. After being extracted by bauxite concentrate, the aluminum content was reduced. During the subsequent roasting of silicon fertilizer, the heavy metal elements (such as Fe and Ti) in the tailings were embedded in the formed stable mineral lattice, thereby solidifying the heavy metals, reducing their bioavailability, and further improving soil quality.

[0038] 5. Closed-loop resource utilization throughout the entire process The production of silicon fertilizer is coordinated with the flotation tailings (A / S<1.5) used to produce high-value-added silicon fertilizer (effective silicon ≥20%). The annual processing of 3 million tons of tailings can produce 500,000 tons of silicon fertilizer (the main product of the tailings is 1.5 million tons of bauxite concentrate, which is used for industrial purposes, such as lending to alumina plants). As a valuable byproduct of tailings treatment, the production of silicon fertilizer generates an additional revenue of ≥300 million yuan per year.

[0039] Land resources have been restored. After treatment, 75% of the 40,000 mu of land occupied by the tailings pond (such as the Guangxi case in other supporting documents) has been restored to arable paddy fields (soil pH increased from 5.0–6.0 to 6.5–7.5, and potassium content increased by 0.2%–0.5%).

[0040] Through pressure filtration dewatering, the moisture content of fine particles can be reduced from approximately 50% of the original tailings to ≤10% (≤20% avoids the risk of dam failure), completely eliminating tailings fluidity and avoiding the risk of dam failure (traditional dry processes have a moisture content ≥35%, which still poses safety hazards). The unit dewatering cost is reduced to 70 yuan / ton, only 50% of the cost of traditional reclamation. Low-moisture-content tailings can be directly processed using conventional transportation equipment, reducing equipment blockage and maintenance costs.

[0041] The technical solution of using flotation tailings for silicon fertilizer production has the following technical advantages: Increased effective silicon content: Through high-temperature roasting (600-900℃) and neutralization reaction, silicate minerals (SiO2≥30.51%) in flotation tailings are converted into soluble sodium silicate, and the effective silicon content of the final silicon fertilizer is ≥20%, which is significantly higher than that of traditional silicon fertilizer (usually 10%-15%).

[0042] Full utilization of bauxite tailings: The efficient extraction of silicon from tailings increases the resource utilization rate of bauxite washing tailings to 98%, avoiding the waste of resources caused by the disposal of silicate minerals in traditional processes.

[0043] Silicon fertilizer market value: Silicon fertilizer with effective silicon content ≥20% is suitable for crops such as rice and sugarcane. The market price is about 600-800 yuan / ton. The annual processing of 3 million tons of tailings can produce about 500,000 tons of silicon fertilizer (the main product of tailings is 1.5 million tons of bauxite concentrate). Silicon fertilizer generates additional economic benefits of ≥300 million yuan / year.

[0044] Cost optimization: Tailings silicon fertilizer production and bauxite recycling are carried out in a coordinated manner, reducing the unit treatment cost by 25%-30% (compared to treating tailings separately).

[0045] Reduce tailings accumulation: Silicon fertilizer production consumes flotation tailings (A / S<1.5), reducing tailings accumulation by about 1.5 million tons per year and alleviating the pressure of tailings ponds occupying land (tailings ponds in Guangxi occupy about 40,000 mu).

[0046] Reduce pollution risk: Heavy metals (such as Fe and Ti) in tailings are solidified in the silicon fertilizer lattice during roasting, and the leaching toxicity is lower than the national standard (GB 5085.3-2007), avoiding soil and groundwater pollution caused by traditional landfill.

[0047] Optimized energy utilization: The roasting process utilizes organic matter (approximately 1.5%-2.0%) from bauxite flotation tailings as auxiliary fuel, reducing energy consumption in silicon fertilizer production. Compared to the traditional electric furnace melting method (melting silicate minerals and then chemically processing them into soluble silicon), energy consumption is reduced by 15%-20%. Product diversification: Silicon fertilizer granules (1-3mm in diameter) can be formulated according to agricultural needs (such as adding potassium and calcium elements) to suit different soil types (such as acidic red soil and sandy soil).

[0048] Flotation tailings are used to replace sand and gravel aggregates in road base construction. The measured unconfined compressive strength of the flotation tailings-based mixture is ≥3.2MPa, resulting in cost savings of ≥37.5%. This meets the strength requirements for heavy-load traffic sections (7-day unconfined compressive strength of cement-stabilized crushed stone base course ≥3.0MPa) and complies with the provisions of the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004).

[0049] Land that was previously uncultivable or degraded due to tailings accumulation (such as rocky desertification areas and land occupied by tailings ponds) can be restored to agricultural land suitable for growing crops such as rice through the treatment method of this invention (flotation tailings + dewatered fine particles + soilification technology). For example, of the 30,000 mu of arable land restored after tailings pond treatment in Guangxi, 75% (approximately 22,500 mu) is suitable for rice cultivation. Using this invention, the paddy field restoration rate after tailings pond treatment is 75%, the soil pH value increases from 5.0-6.0 to 6.5-7.5, and the potassium content increases by 0.2%-0.5%.

[0050] This invention uses potassium carbonate to replace sodium carbonate in the existing technology, and the sodium ion content in the tailings is ≤0.1%, thus avoiding the damage of sodium ions to the soil aggregate structure.

[0051] Using this invention, 3 million tons of tailings can be treated annually, 1.5 million tons of bauxite concentrate can be recovered for industrial use, and about 500,000 tons of silicon fertilizer can be produced for agricultural use. The area of ​​tailings soil treatment is ≥30,000 mu, and the direct economic benefits are ≥300 million yuan (the market value of 500,000 tons of silicon fertilizer alone is ≥300 million yuan). Attached Figure Description

[0052] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0053] In this embodiment, expressions of numerical ranges such as "20%-25%" include both extreme values.

[0054] like Figure 1 As shown, the method for resource utilization and treatment of bauxite washing tailings ponds according to the present invention is carried out according to the following steps: A method for the resource-based treatment of bauxite washing tailings ponds, characterized by comprising the following steps: The first step is to perform hydrocyclone classification on the tailings in the tailings pond. Based on the characteristic that the aluminum-silicon ratio (A / S, which refers to the weight ratio of aluminum oxide to silicon dioxide) of relatively coarse ore particles is higher than that of fine particles, coarse particles with A / S greater than or equal to Y and fine particles with A / S less than Y are separated; 1.2≤Y≤3.0. The second step is to grind and flotate the coarse particles. During the grinding process, a dispersant is added and the pH of the slurry is adjusted to 8.0-10.5. During the flotation process, sodium oleate is added as a collector to obtain bauxite concentrate and flotation tailings. The third step: Dewater the fine particles to obtain dewatered tailings with a moisture content of ≤20%; The fourth step involves adding a solidifying agent or soil conditioner to the dewatered flotation tailings and dewatered tailings to form arable soil for ecological restoration in rocky desertification areas.

[0055] During the grinding process of the bauxite, potassium carbonate is added as a dispersant and pH adjuster; the amount of potassium carbonate added is 0.1%-0.5% of the dry weight of the flotation tailings, and the potassium carbonate in the flotation tailings is used as potassium fertilizer to improve acidic soil.

[0056] The flotation process described in the second step employs a composite flotation technique, including: For coarse particles with A / S≥Y, a single roughing, three scavenging, and one cleaning flotation process is performed, with a concentrate recovery rate ≥35%. The specific process of one coarse selection, three scans, and one fine selection includes the following continuous sub-steps: (1) Roughing: The pulp conditions in this step include a pulp concentration of 20%-35%, pH of 8.0-10.5, and sodium oleate addition of 300-1000 g / dry ton; the dry ton in the addition amount refers to the weight of the dried slime, and the gram in the addition amount refers to the amount of additive added; the flotation time in this sub-step is 5-10 minutes. The initial separation process of this process initially separates bauxite concentrate with an A / S ratio ≥ 2.5 and rougher tailings with an A / S ratio ≤ 2.5. The concentrate with an A / S ratio ≥ 2.5 enters the cleaning process, while the rougher tailings with an A / S ratio ≤ 2.5 enter the first scavenging process. (2) For the first sweep, the amount of reagents added in this step is: 100-300 g / dry ton of sodium oleate; the flotation time in this step is 5-8 minutes. This step recovers residual bauxite with an A / S ratio ≥ 2.5 from the roughing tailings, which is then used as primary scavenging concentrate froth in the cleaning process. Scavenging tailings with an A / S ratio < 2.2 are then used for secondary scavenging. (3) Second sweeping, the amount of reagent added in this step is: sodium oleate added 0-300 g / dry ton; flotation time in this step: 5-8 minutes; This step recovers residual bauxite with an A / S ratio ≥ 2.5 from the primary scavenging tailings, which is then used as secondary scavenging concentrate foam to enter the cleaning process. Secondary scavenging tailings with an A / S ratio < 2.0 are then used for the third scavenging. (4) The amount of reagent added in the third sweep step is: sodium oleate 0-300 g / dry ton; the flotation time in this step is 5-8 minutes. This step recovers residual bauxite with an A / S ratio ≥ 2.5 from the secondary scavenging tailings, which is then used as flotation concentrate in the tertiary scavenging process. The tertiary scavenging tailings with an A / S ratio < 1.5 are used as flotation tailings. (5) Fine selection, the amount of reagent added in this step is: sodium oleate added 0-300 g / dry ton; the flotation time in this step is 5-8 minutes; This process involves collecting the froth from the roughing, primary scavenging, secondary scavenging, and tertiary scavenging processes for further cleaning. Bauxite with an A / S ratio ≥ 4.5 is recovered as the final flotation concentrate. The cleaned tailings with an A / S ratio < 3.0 are returned to the roughing or primary scavenging process. The final flotation concentrate is used for alumina production or refractory material manufacturing.

[0057] The dewatering process in the third step specifically includes sedimentation concentration dewatering and filter press dewatering. After dewatering, the moisture content of the fine particles is ≤20%. In the fourth step, the dewatered tailings are transformed into arable soil through soilification technology, with an organic matter content ≥2%.

[0058] The solidifying agent mentioned in step four is lime or cement, added at 5%-10% of the dry weight of the tailings. The soil conditioner includes organic matter and calcium silicate fertilizer, added at 3%-10% of the dry weight of the tailings. The specific ratio of organic fertilizer to calcium silicate fertilizer in the soil conditioner can be adjusted according to actual needs, with the core constraint being that the total amount of soil conditioner added is ≤5%. Different rocky desertification areas have different soil nutrient deficiencies (e.g., soils in Guangxi are generally deficient in potassium and silicon), and the ratio of organic fertilizer to calcium silicate fertilizer should be determined according to the specific soil nutrient deficiencies.

[0059] It also includes a silicon fertilizer production step, in which the flotation tailings are used for silicon fertilizer production. Specific steps include: Flotation tailings are mixed with sodium hydroxide (the amount of sodium hydroxide added is 15%-25% of the dry weight of the flotation tailings) and roasted at 600-900℃ for 1.5-3 hours to produce sodium silicate. After neutralization and drying, granular silicon fertilizer is produced with an effective silicon content of ≥20%. The roasting process utilizes the organic matter (content of about 1.5%-2.0%) in the flotation tailings as auxiliary fuel.

[0060] The technical solution of using flotation tailings for silicon fertilizer production has the following technical advantages: Increased effective silicon content: Through high-temperature roasting (600-900℃) and neutralization reaction, silicate minerals (SiO2≥30.51%) in flotation tailings are converted into soluble sodium silicate, and the effective silicon content of the final silicon fertilizer is ≥20%, which is significantly higher than that of traditional silicon fertilizer (usually 10%-15%).

[0061] Full utilization of bauxite tailings: The efficient extraction of silicon from tailings increases the resource utilization rate of bauxite washing tailings to 98%, avoiding the waste of resources caused by the disposal of silicate minerals in traditional processes.

[0062] Silicon fertilizer market value: Silicon fertilizer with effective silicon content ≥20% is suitable for crops such as rice and sugarcane. The market price is about 600-800 yuan / ton. The annual processing of 3 million tons of tailings can produce about 500,000 tons of silicon fertilizer (the main product is 150 tons of bauxite concentrate). Silicon fertilizer generates additional economic benefits of ≥300 million yuan / year.

[0063] Cost optimization: Tailings silicon fertilizer production and bauxite recycling are carried out in a coordinated manner, reducing the unit treatment cost by 25%-30% (compared to treating tailings separately).

[0064] Reduce tailings accumulation: Silicon fertilizer production consumes flotation tailings (A / S<1.16), reducing tailings accumulation by about 1.5 million tons per year and alleviating the pressure of tailings ponds occupying land (tailings ponds in Guangxi occupy about 40,000 mu).

[0065] Reduce pollution risk: Heavy metals (such as Fe and Ti) in tailings are solidified in the silicon fertilizer lattice during roasting, and the leaching toxicity is lower than the national standard (GB 5085.3-2007), avoiding soil and groundwater pollution caused by traditional landfill.

[0066] Optimized energy utilization: The roasting process utilizes organic matter (approximately 1.5%-2.0%) from bauxite flotation tailings as auxiliary fuel, reducing energy consumption in silicon fertilizer production. Compared to the traditional electric furnace melting method (melting silicate minerals and then chemically processing them into soluble silicon), energy consumption is reduced by 15%-20%. Product diversification: Silicon fertilizer granules (1-3mm in diameter) can be formulated according to agricultural needs (such as adding potassium and calcium elements) to suit different soil types (such as acidic red soil and sandy soil).

[0067] The flotation tailings are used to replace sand and gravel aggregates in road base construction.

[0068] Flotation tailings are used to replace sand and gravel aggregates in road base construction. The measured unconfined compressive strength of the flotation tailings-based mixture is ≥3.2MPa, resulting in cost savings of ≥37.5%. This meets the strength requirements for heavy-load traffic sections (7-day unconfined compressive strength of cement-stabilized crushed stone base course ≥3.0MPa) and complies with the provisions of the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004).

[0069] Land that was previously uncultivable or degraded due to tailings accumulation (such as rocky desertification areas and land occupied by tailings ponds) can be restored to agricultural land suitable for growing crops such as rice through the treatment method of this invention (flotation tailings + dewatered fine particles + soilification technology). For example, of the 30,000 mu of arable land restored after tailings pond treatment in Guangxi, 75% (approximately 22,500 mu) is suitable for rice cultivation. Using this invention, the paddy field restoration rate after tailings pond treatment is 75%, the soil pH value increases from 5.0-6.0 to 6.5-7.5, and the potassium content increases by 0.2%-0.5%.

[0070] This invention uses potassium carbonate to replace sodium carbonate in the existing technology, and the sodium ion content in the tailings is ≤0.1%, thus avoiding the damage of sodium ions to the soil aggregate structure.

[0071] Using this invention, 3 million tons of tailings can be treated annually, 1.5 million tons of bauxite concentrate can be recovered, and about 500,000 tons of silicon fertilizer can be produced. The area of ​​tailings soil treatment is ≥30,000 mu, and the direct economic benefit increment is ≥300 million yuan (the market value of 500,000 tons of silicon fertilizer alone is ≥300 million yuan).

[0072] The above embodiments are only used to illustrate and not limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention without departing from the spirit and scope of the present invention. Any modifications or partial substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for the resource-based treatment of bauxite washing tailings ponds, characterized in that, Includes the following steps: The first step is to perform hydrocyclone classification on the tailings in the tailings pond. Based on the characteristic that the aluminum-silicon ratio of relatively coarse ore particles is higher than that of fine particles, coarse particles with A / S greater than or equal to Y and fine particles with A / S less than Y are separated. 1.2≤Y≤3.0； The second step is to grind and flotate the coarse particles. During the grinding process, a dispersant is added and the pH of the slurry is adjusted to 8.0-10.

5. During the flotation process, sodium oleate is added as a collector to obtain bauxite concentrate and flotation tailings. The third step: Dewater the fine particles to obtain dewatered tailings with a moisture content of ≤20%; The fourth step involves adding a solidifying agent or soil conditioner to the dewatered flotation tailings and dewatered tailings to form arable soil for ecological restoration in rocky desertification areas.

2. The method for resource-based treatment of bauxite washing tailings ponds according to claim 1, characterized in that: During the grinding process of the bauxite, potassium carbonate is added as a dispersant and pH adjuster; the amount of potassium carbonate added is 0.1%-0.5% of the dry weight of the flotation tailings, and the potassium carbonate in the flotation tailings is used as potassium fertilizer to improve acidic soil.

3. The method for resource-based treatment of bauxite washing tailings ponds according to claim 2, characterized in that: The flotation process described in the second step employs a composite flotation technique, including: For coarse particles with A / S≥Y, a single roughing, three scavenging, and one cleaning flotation process is performed, with a concentrate recovery rate ≥35%. The specific process of one coarse selection, three scans, and one fine selection includes the following continuous sub-steps: (1) Roughing: The pulp conditions in this step include a pulp concentration of 20%-35%, pH of 8.0-10.5, and sodium oleate addition of 300-1000 g / dry ton; the flotation time in this sub-step is 5-10 minutes. The initial separation process of this process initially separates bauxite concentrate with an A / S ratio ≥ 2.5 and rougher tailings with an A / S ratio ≤ 2.

5. The concentrate with an A / S ratio ≥ 2.5 enters the cleaning process, while the rougher tailings with an A / S ratio ≤ 2.5 enter the first scavenging process. (2) For the first sweep, the amount of reagents added in this step is: 100-300 g / dry ton of sodium oleate; the flotation time in this step is 5-8 minutes. This step recovers residual bauxite with an A / S ratio ≥ 2.5 from the roughing tailings, which is then used as primary scavenging concentrate froth in the cleaning process. Scavenging tailings with an A / S ratio < 2.2 are then used for secondary scavenging. (3) Second sweeping, the amount of reagent added in this step is: sodium oleate added 0-300 g / dry ton; flotation time in this step: 5-8 minutes; This step recovers residual bauxite with an A / S ratio ≥ 2.5 from the primary scavenging tailings, which is then used as secondary scavenging concentrate foam to enter the cleaning process. Secondary scavenging tailings with an A / S ratio < 2.0 are then used for the third scavenging. (4) The amount of reagent added in the third sweep step is: sodium oleate 0-300 g / dry ton; the flotation time in this step is 5-8 minutes. This step recovers residual bauxite with an A / S ratio ≥ 2.5 from the secondary scavenging tailings, which is then used as flotation concentrate in the tertiary scavenging process. The tertiary scavenging tailings with an A / S ratio < 1.5 are used as flotation tailings. (5) Fine selection, the amount of reagent added in this step is: sodium oleate added 0-300 g / dry ton; the flotation time in this step is 5-8 minutes; This process involves collecting the concentrate froth from roughing, primary scavenging, secondary scavenging, and tertiary scavenging for further cleaning. Bauxite with an A / S ratio ≥ 4.5 is recovered as the final flotation concentrate. The cleaned tailings with an A / S ratio < 3.0 are returned to the roughing or primary scavenging process.

4. The method for resource-based treatment of bauxite washing tailings ponds according to claim 1, characterized in that: The dewatering process in the third step specifically includes sedimentation concentration dewatering and filter press dewatering. After dewatering, the moisture content of the fine particles is ≤20%. In the fourth step, the dewatered tailings are transformed into arable soil through soilification technology, with an organic matter content ≥2%.

5. The method for resource-based treatment of bauxite washing tailings ponds according to claim 1, characterized in that: The solidifying agent mentioned in the fourth step is lime or cement, and the amount added is 5%-10% of the dry weight of the tailings; the soil conditioner includes organic matter and silicon-calcium fertilizer, and the amount added is 3%-10% of the dry weight of the tailings.

6. The method for resource-based treatment of bauxite washing tailings ponds according to claim 1, characterized in that: It also includes a silicon fertilizer production step, in which the flotation tailings are used for silicon fertilizer production. Specific steps include: The flotation tailings are mixed with sodium hydroxide and roasted at 600-900℃ for 1.5-3 hours to produce sodium silicate. After neutralization and drying, it is made into granular silicon fertilizer with an effective silicon content of ≥20%.

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