Key technologies for preparation and multi scene utilization of multi-source solid waste based carbon fixation mining materials

During the production of metallurgical industry and the development of coal resources, a large number of solid wastes that are difficult to be effectively utilized are produced, accompanied by surface subsidence, solid waste stockpiling and high carbon emissions. In order to achieve the goal of "coal mine loss reduction mining-functional utilization of solid waste-CO₂ low-carbon disposal", this study innovatively proposed the key technologies of CO₂ mineralization multi-source solid waste preparation of carbon fixation mining materials and multi scenario utilization.Taking the modified magnesium coal based solid waste (including modified magnesium slag, fly ash and coal gangue) as an example, the direct mineralization method was used to mineralize it on the ground to prepare carbon fixation mining materials, so as to meet the application requirements of multiple scenarios in the mine. In this paper, the process of direct mineralization of solid waste and its key influencing factors were systematically analyzed, and the modified magnesium coal based solid waste carbon fixation mining materials were prepared. The basic properties (flow performance, strength performance, carbon fixation ability) and carbon fixation mechanism of the modified magnesium coal based solid waste carbon fixation mining materials under different liquid-solid ratios were studied.The results show that when the liquid-solid ratio is greater than 0.23, the material meets the backfill flow performance requirements, and the maximum 28 day compressive strength can reach 6.18 MPa; The mineralization efficiency of direct mineralization mixing for 10 minutes reached 50.7%. Aiming at the problem of multi scene utilization of multi-source solid waste based carbon fixation mining materials, this paper puts forward the key technologies of multi scene utilization, including "carbon fixation mining prefabricated parts, carbon fixation paste backfill mining, carbon fixation mining materials for goaf treatment, and carbon fixation backfill materials for mine cooling". Based on the carbon fixation mine prefabricated parts, the integrated technology and equipment of high-strength and low-permeability reservoir wall construction technology and roadway excavation floor laying are proposed; On the basis of paste backfill mining in the mine, this paper innovatively puts forward the room and pillar coal mining carbon fixation backfill coal pillar recovery technology and the integrated equipment of efficient preparation and backfill application of metallurgical coal based solid waste carbon fixation backfill material. In addition, in the application of goaf treatment, it is also necessary to study the adsorption diffusion mechanism of CO₂ in solid waste materials, the multi field coupling mechanism between grouting materials and the environment, and the CO₂ efficient absorption mixing reaction device, and establish the application system of "goaf hazard monitoring-solid waste mineralization grouting material treatment-grouting effect evaluation". This study provides a useful reference for the rational disposal of bulk metallurgical coal based solid waste and the efficient storage of CO₂, and is of great significance to promote the realization of the dual carbon goal and the transformation and development of coal mining areas from "zero carbon" to "negative carbon".