Method for preparing cementing material from bauxite mill tailings

Abstract

The invention relates to a method for preparing a cementing material from bauxite mill tailings, and belongs to the technical field of comprehensive utilization of industrial solid waste. The method comprises the following steps that (1) the bauxite mill tailings are added into red mud for drying, and coal gangue is graded and screened for later use; (2) a heat value of the mixture is prepared, and crushing and precipitating are performed; (3) forming, setting and drying are performed; (4) calcining and quenching are performed; clinker A is prepared; (5) industrial by-product gypsum is modified at the low temperature by the aid of quenching waste heat to prepare building gypsum B, and the raw materials and a mixture blank are dried; and (6) the clinker A, the building gypsum B, a composite activator and an auxiliary agent are taken, and fine grinding is performed to obtain the cementing material. The low-grade coal gangue is utilized to calcine the tailings and the red mud, so that the modified clinker has the capability of adsorbing heavy metals, the activator and the auxiliary agent are added, and the finished product is prepared through fine grinding. The product is stable in performance, wide in application and environment-friendly; the waste heat is utilized to modify the industrial by-product gypsum, so that the method is low in consumption and high in value, and a feasible technical route is provided for large-scale utilization of the industrial solid waste.

Description

technical field [0001] The invention belongs to the technical field of comprehensive utilization of industrial solid waste, in particular to a method for preparing cementitious materials from bauxite beneficiation tailings. Background technique [0002] Bauxite beneficiation tailings is one of the main industrial solid wastes of non-ferrous metal tailings. Its particles are fine, its shape is weak and sticky, its sedimentation speed is slow, and it has no cementation. It is difficult to use and has a huge stockpile. Coal gangue is a kind of black-gray rock with low carbon content but harder than coal that is associated with coal seams during the coal formation process. It is the solid with the largest emission in the coal mining industry. waste, and the heavy metals in coal gangue are prone to weathering and migration after long-term natural erosion, and infiltrate into the soil with precipitation to pollute groundwater; red mud is another solid waste in the alumina producti...

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Problems solved by technology

Although the above two invention patents provide a new idea for the use of tunnel kiln sintering process to process industrial solid waste to prepare cementitious materials, coal gangue is used as part of the fuel and calcined at 950°C-1400°C for 0.25-24h. It needs to add a large amount of coal or coal stones as the heat source for calcination, and does not take into account the technical problems that the section of the tunnel kiln is large, and the ingredients, heat radiation, and heat exchange must be scientifically matched with the sintering space to ensure the sintering quality, so the energy consumption is large and the thermal efficiency is low. The output is low, the cost is high, the sintering quality cannot be guaranteed, and the scale production cannot be formed, and it does not involve the treatment of alkali content and heavy metals in solid waste and the comprehensive utilization of sintering waste heat

[0006] Patent No. CN112745049A discloses a coal gangue-based admixture and its preparation method, using 80-90 parts of coal gangue as raw material, pre-grinding it into powder, and then mixing coal gangue powder with 5-15 parts of calcium oxide Wet mixing, steaming and calcination with 5-15 parts of gypsum, then cooling the calcined product and co-grinding with 3-6 parts of silane coupling agent, and finally combining the co-grinding product with 15-20 parts Fly ash and 5-10 parts of limestone powder are mixed to obtain the gangue-based admixture; this patent only uses gangue as a concrete admixture, and does not involve gangue as a kind of energy that can provide heat to Other solid wastes are calcined, and other solid wastes can be treated by the waste heat of self-combustion, and there are many procedures, high energy consumption, low production capacity, complex process, and there are certain limitations. Compared with similar products, there is no price advantage.

[0007] Based on the above-mentioned patented technologies and research results, it is found that most of the bauxite beneficiation tailings (co-associated ore), red mud, and industrial by-product gypsum are hydrophilic solid wastes. The mineral components of cement, through drying and dehydration, alkali excitation, metal salt activation, thermal activation, mechanical activation, the production of artificial cementitious materials to replace cement in a certain range of use, has become a hot topic in this technical field; but The comprehensive utilization of bauxite beneficiation tailings, coal gangue, red mud and titanium gypsum in the prior art does not involve the treatment of alkali content and heavy metals in solid waste and the comprehensive utilization of sintering waste heat, and there are immature technologies and limitations Large-scale, many processes, high energy consumption, low thermal efficiency, low output, high cost and unstable quality, etc., cannot form large-scale production

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