Bayer process alumina and associated resources integrated and synergistic extraction and tailings harmless process

Abstract

The application discloses a process for integrally and cooperatively extracting alumina and associated resources and harmlessly preparing construction waste from tailings, and belongs to the technical field of comprehensive utilization of aluminum ore resources and solid waste environmental protection. The application is based on the primary high-temperature and high-pressure reaction condition of the Bayer process for producing alumina, does not need to additionally add lime for desilication, is matched with special composite additives, synchronously dissociates and recycles all associated valuable components while dissolving alumina, does not need secondary high-temperature melting processing at the rear end, saves a large number of processes, equipment and energy consumption; after the valuable components are completely recycled, the waste residue is simply neutralized to achieve harmlessness, and finally, the tailings reach the general civil engineering recycled material standard, and the industry pain points of low resource utilization rate, high deep processing cost and red mud solid waste pollution in the traditional process are completely solved. The application has the advantages of simple process, strong compatibility, low landing cost, economic value and environmental protection value, and is suitable for large-scale industrialized popularization and application.

Description

Technical Field

[0001] This invention relates to the fields of bauxite Bayer process production, comprehensive recovery of associated valuable metals, and harmless environmental protection technology of industrial solid waste. Specifically, it relates to an integrated green production process that relies on the primary leaching of alumina to simultaneously recover multiple valuable metals and convert end-of-life waste into general civil engineering reusable materials. Background Technology

[0002] The Bayer process for producing alumina from bauxite is the mainstream technology in the industry. Bauxite naturally contains valuable metals such as iron, titanium, vanadium, and rare earth elements. However, existing industrial processes and technologies suffer from a core fatal flaw: The traditional Bayer process only extracts alumina by directional leaching and only loosens the crystal lattice of iron and titanium minerals. It cannot achieve the dissociation and recovery of rare earth elements. Rare earth elements remain in the red mud waste throughout the process, resulting in extremely low resource utilization. To recover iron and titanium components from the waste residue, existing technologies require secondary processing of the discharged red mud, which necessitates the construction of dedicated equipment and high-temperature melting treatment at 1500-1700℃. This adds a significant number of production steps, equipment investment, and energy consumption, resulting in high production costs. Even after high-temperature remedial treatment, the tailings still contain unextracted rare earth components and highly alkaline substances, which can only be classified as Class II industrial solid waste. They must be stored in a dedicated seepage-proof storage site and cannot be used directly. The global problem of red mud storage causing land occupation and water and soil pollution has remained unsolved. All existing publicly available patents and industrialization projects adopt a passive technical route of first producing red mud and then remediating at the end. They do not simultaneously achieve integrated recovery of all components such as aluminum, iron, titanium, and rare earth during the primary leaching stage of alumina, and they cannot convert the final waste residue into general civil engineering reusable materials. Summary of the Invention

[0003] Purpose of the invention To address the shortcomings of existing technologies, such as cumbersome processes, high energy consumption, waste of valuable resources, and severe solid waste pollution, this paper proposes a process for the integrated co-extraction of alumina with associated iron, titanium, and rare earth elements, and the harmless treatment of tailings to prepare reusable materials for civil engineering. Utilizing the inherent high-temperature and high-pressure conditions of alumina production, this process eliminates the need for secondary heating and pressurization, as well as high-temperature melting equipment at the back end. All valuable components are extracted simultaneously in one step, and the waste residue is simply neutralized at the end, completely resolving industry pain points.

[0004] Core technology principles First, high-silica bauxite is pretreated with a special composite additive to remove silica and calcium, effectively reducing the amount of red mud produced. Then, relying on the high-temperature, high-pressure, and strongly alkaline environment of Bayer process alumina production, the efficient leaching of valuable components such as iron, titanium, and rare earth elements is achieved simultaneously without disrupting the leaching balance of aluminum minerals or affecting the alumina recovery rate. No additional reaction conditions are required, and multiple valuable elements are dissociated and recovered in one go using existing production conditions. The weakly alkaline water precipitated during the separation of valuable components is all recycled in a closed loop, concentrated to prepare a standard concentrated alkali solution, and then fed into the reactor for recycling. After the separation of valuable components, the waste residue has only a trace amount of alkalinity. The pH is adjusted by simple acid-base neutralization without complex deep processing. The waste residue meets the standards for general civil engineering recycled materials and can be used compliantly for engineering backfilling, roadbeds, and brick-making raw materials, eliminating the problem of solid waste stockpiling of Bayer process red mud from the source.

[0005] Specific process steps Native working conditions co-dissolution The bauxite is ground and fed into a stirred tank. A special composite additive is added to complete the desiliconization and decalcification pretreatment of the high-silicon bauxite. Then it is sent into a high-temperature and high-pressure reactor. During the entire process of alumina leaching, the lattice dissociation and component leaching of iron, titanium, vanadium and rare earth minerals are realized simultaneously. The entire process uses the existing production line without adding new heating, pressurizing and roasting equipment, and without increasing additional production energy consumption.

[0006] Multi-component stepwise sorting and recovery After leaching, the slurry undergoes solid-liquid separation, and alumina, iron-based components, titanium-based components, vanadium components, and rare earth components are extracted in a stepwise manner. All valuable resources associated with bauxite are fully recovered, achieving complete utilization of mineral resources, which is different from the existing single recovery model that only extracts aluminum, loosens iron and titanium, and abandons rare earth.

[0007] Tailings liquid recirculation and reuse, and simple harmless treatment of tailings residue The weakly alkaline water precipitated during the separation of valuable components is all recycled in a closed loop, and after concentration, it is prepared into a standard concentrated alkaline solution and put into the reactor for recycling. After all valuable elements are separated, the remaining waste residue has only a trace amount of residual alkalinity. Conventional acid neutralizing reagents are added to the waste residue to simply adjust its physicochemical properties, so that the acidity and alkalinity of the waste residue tends to be neutral and achieves harmlessness.

[0008] Compliant Resource Utilization of Waste The neutralized tailings contain no toxic or harmful precipitates, no high alkalinity hazards, and their physicochemical properties and environmental protection indicators meet the standards for general civil engineering reusable materials. They are no longer classified as polluting red mud or industrial hazardous solid waste, and can be directly discharged for reuse, mine backfilling, roadbed paving, and brick making, without the costs of solid waste storage or environmental compliance risks.

[0009] Core innovative advantages of this invention Saves processes, equipment, and energy. Based on the existing alumina production conditions, there is no need to add lime for desilication, and the industry-standard route of secondary high-temperature melting after red mud discharge is abandoned. There is no need to add heating equipment at the back end, and there is no increase in equipment purchase and energy consumption costs, which greatly reduces the amount of red mud generated and the cost of treatment.

[0010] Full-dimensional recycling of valuable elements Overcoming the shortcomings of existing technologies that only extract aluminum without extracting associated resources, this technology simultaneously achieves integrated recovery of aluminum, iron, titanium, vanadium, and rare earth elements in the same leaching process, resulting in a resource utilization rate significantly higher than similar existing publicly available processes and industrial projects.

[0011] Completely render waste harmless and achieve solid waste downgrading. Unlike its competitors, whose treated waste remains classified as Class II industrial solid waste, this process ensures that the physicochemical stability of the treated waste meets the standards, directly downgrading it to general civil engineering reusable materials. This addresses the industry's problems of red mud pollution and land occupation caused by its storage, demonstrating extremely high environmental value.

[0012] High process compatibility and easy implementation It can be implemented without modifying existing main alumina production lines. It only requires the addition of special compatible additives and a simple neutralization section. It is compatible with all Bayer process alumina plants and has a low threshold for industrialization.

Claims

1. A process for the integrated synergistic extraction of alumina and associated resources and the harmless treatment of tailings to prepare construction waste, characterized in that, Includes the following steps: 1) Synergistic leaching under original working conditions: After grinding, bauxite is fed into a stirred tank, and a special composite additive is added to complete the desiliconization and decalcification pretreatment of high-silica bauxite. Then it is sent into a high-temperature and high-pressure reactor. During the entire process of alumina leaching, the lattice dissociation and component leaching of iron, titanium, vanadium and rare earth minerals are realized simultaneously. 2) Multi-component separation and recovery: solid-liquid separation of leached slurry, stepwise recovery of all valuable associated components such as alumina, iron, titanium, vanadium, and rare earth elements; tailings generated during the separation process are recycled, concentrated to prepare a standard concentrated alkali solution, and then fed into the reactor for reuse. 3) Simple neutralization of tailings: The remaining waste residue after the extraction of valuable components is simply neutralized with an acidic reagent to adjust the pH value of the waste residue to neutral. 4) Waste residue recycling: The neutralized tailings meet the requirements of the "Standard for Pollution Control of Storage and Landfill of General Industrial Solid Waste" (GB 18599) and "Sand for Construction" (GB / T 14684) and can be directly used for engineering backfilling, roadbed paving and brick making.