Waste Backfill Research Articles

Innovative solid waste backfilling technology for top coal caving mining: analysing top coal movement and recovery optimisation

ABSTRACT The study introduces a novel solid backfilling technology, aiming to address gangue accumulation problem in top coal caving mining. To reveal its top coal drawing mechanism, discrete physical and numerical models were established. During the initial drawing stage, considerable amounts of low-position top coal are extracted, with yields fluctuating. As the working face advances, the drawing body shape shifts from knife-handle to semi-arch, and coal-gangue boundary curvature varies periodically. At low backfilling ratios, premature gangue exposure causes the loss of high-position top coal. Conversely, higher backfilling ratios facilitate the creation of a reconstructed floor, thereby enhancing top coal recovery.

Mechanism of air-entraining agent to improve the properties of coal-based solid waste backfill

Fly ash exhibits volcanic ash activity and can be utilized as a cementitious material to reduce filling costs. The limited flow characteristics of mine solid waste filling slurry can impact backfill efficiency. Instead of using a large amount of cement, we employ fly ash as a cementing material to prepare filling slurries with varying air-entraining agent dosages. The results indicate that as the air-entraining agent dosage increases from 0 to 8%, the fluidity of the filling slurry improves, and the strength increases within the first 5 days of curing. The strength of the filling increases initially from 5 to 28 days of curing with the increase in air-entraining agent dosage, reaching a peak at 4% dosage, with an 11.35% higher strength compared to the filling body without the air-entraining agent. The microscopic pore structure and hydration product analysis reveal that introducing an appropriate amount of bubbles results in an even distribution of cementitious material and aggregates, improving fluidity and strength. However, excessive addition of air-entraining agents inhibits the growth of C–S–H and the filling ability of AFt for primary pores, ultimately impacting the long-term strength growth of the filling body.

Investigation of the Long-Term Performance of Waste Backfill Materials of High Thermal Conductivity in Vertical Ground Heat Exchangers

Investigation of the Long-Term Performance of Waste Backfill Materials of High Thermal Conductivity in Vertical Ground Heat Exchangers

Experimental Investigation on Hydrophobic Alteration of Mining Solid Waste Backfill Material

To address the issues of corrosion weakening of solid-waste-based backfill material caused by mine water, a novel hydrophobic solid waste backfill (HSBF) material was developed using polydimethylsiloxane (PDMS) and a silane coupling agent (SCA) as hydrophobic modification additives, and NaOH (SH) and sodium silicate (SS) as alkali activators. Fly ash and slag were chosen as the primary raw solid waste materials. The rheological properties of the hydrophobic-treated backfill slurries were measured, and the resulting physicochemical properties were compared with the unmodified reference group. This study reveals that the fresh HSBF slurry follows a Modified Bingham (M-B) model with shear-thinning characteristics. The addition of PDMS causes an increase in the water contact angle of the hardened HSBF material with F8S2 to up to 134.9°, indicating high hydrophobicity. Morphological observations indicated that PDMS mainly attaches to the inorganic particles’ surface through the bridging action of SCA for the hydrophobic modification of the backfill material. The overall strength of the HSBF materials was further ensured via fly ash–slag ratio optimization, and was found to be enhanced up to 98% by increasing slag content from 20% to 50%. This is mainly attributed to the hydration of slag, forming C-S(A)-H gel, which contributes to the increased strength. The novel HSBF material enables the elimination of cement in mine backfilling applications, demonstrating good economic benefits. Its excellent mechanical and hydrophobic properties can not only prevent overburden displacement in goaf areas, but can also mitigate water resource loss from overlying strata and simultaneously reduce the safety risks associated with long-term mine water deterioration.

A backfill material without cementitious material: Carbonation curing magnesium slag based full solid waste backfill material

A backfill material without cementitious material: Carbonation curing magnesium slag based full solid waste backfill material

Carbonation curing of magnesium-coal slag solid waste backfill material: Study on properties of flow, mechanics and carbon sequestration

To expedite the achievement of the ''30–60 double carbon'' goal, it is imperative to create a novel, low-carbon, cost-effective, and sustainable backfill material for mining purposes. Against this background, this paper investigates the workability, carbonation performance and carbon sequestration capacity of coal gangue (CG), magnesium slag (MS) and fly ash (FA) as magnesium coal slag solid waste backfill material. The results of the study show that: (1) The rheological properties of the CFM fresh slurry conform to the Herschel-Balkley (H-B) model, and its flowability meets the requirements of mine backfill transport. With increasing MS content, the yield stress, apparent viscosity, thixotropy and shear thickening of CFM fresh slurry increase, and the micro-slump and diffusion diameter decrease. (2) Carbonation curing can effectively improve the early UCS of CFM. The highest UCS of CFM was 8.854 MPa after 7 days of carbonation curing, which was 27.84 times higher than that of standard curing. In addition, the UCS of CFM increased with the increase of curing age and MS content. (3) CFM produces a large number of carbonation products such as calcium carbonate after carbonation curing, which makes its microstructure denser. (4) CFM can absorb up to 14.55 % of CO2 after carbonation. (5) The volume stability of CFM is significantly improved after carbonation curing. In summary, CFM is not only a new type of low-cost, low-carbon and sustainable solid waste backfill material, but its practical application in the field of mine backfilling also has great potential for the realization of magnesium coal slag solid waste resource utilization and CO2 sequestration.

Gangue grouting filling in subsequent space of coal green mining: methodology and case study

Underground backfilling stands out as a crucial technological strategy for the eco-friendly and effective management of solid waste in mining operations. However, existing backfilling techniques have led to increased production processes at the working face, resulting in a reduction in coal extraction efficiency. Addressing the temporal and spatial interference between mine solid waste backfilling and coal mining is essential. To overcome this challenge, this study introduces a novel post-mining spatial gangue slurry backfilling method. Radar detection was employed to ascertain the typical characteristics of the subsequent space collapse roof shape. Stress monitoring and compaction experiments were conducted to establish the relationship between stress and the bulking coefficient of the overlying rock mass, identifying subsequent spatial void structure characteristics. The development of a CO2 mineralized coal-based solid waste filling material, utilizing conventional low-calcium fly ash under normal temperature and pressure conditions, was presented. This paper provides a comprehensive understanding of the post-mining spatial gangue slurry backfilling method, outlines the spatial layout approach for the corresponding system, and analyzes research challenges associated with gangue slurry backfilling materials and the technology of slurry injection borehole layout. The research aims to innovate an efficient underground disposal model for gangue, contributing to the refinement of the technical system for the comprehensive disposal and utilization of gangue.

Mix proportion and microscopic characterization of coal-based solid waste backfill material based on response surface methodology and multi-objective decision-making

The mix proportion of multi-source coal-based solid waste (CSW) for underground backfilling affects transportation and support performance of backfill materials, and even the backfilling cost. In this study, the optimal mix proportion of desulfurization gypsum (DG), furnace bottom slag (FBS) and gasification fine slag (GFS) is determined by the Response Surface Methodology–Box Behnken Design (RSM-BBD). Then the fluidity, bleeding rate, 3-day strength, 7-day strength and preparation cost are evaluation indicators, the optimal mix proportion of backfill materials is determined by the multi-objective decision-making method (MDM). Finally, the microstructure of the backfill material with optimal mix proportion was studied by TGA, MIP, SEM–EDS and XRD. The results show that the mix proportion of CSW with the optimal comprehensive index is coal gangue (CG): coal fly ash (CFA): DG: FBS: GFS = 1:1.5:0.2:0.1:0.1, the mass concentration is 78%, and ordinary Portland cement (OPC)/CSW = 7.5%. The weight loss phenomenon of the backfill material with the optimal mix proportion occurs continuously during the heating process, mainly due to the evaporation of crystal water, structural water and hydroxyl water. There are dense narrow-necked pores in the backfill material, and the pore connectivity is poor. There is no hydration reaction occurs between CSW particles, and the strength increase of the backfill material mainly depends on the hydration reaction of cement. In ettringite, part of Al2O3 is replaced by SiO2, and part of CaSO4 is replaced by CaCO3. This study provides a reference for the engineering application of underground backfilling with multi-source CSW.

Strength characteristics and carbonation depth evolution of modified magnesium slag based solid waste storage backfill materials

CO2 storage is one of the effective ways to achieve China's 30·60 dual carbon goal. The study of the interaction between CO2 and storage backfill material lays a foundation for the long-term stability and gas tightness of CO2 storage. Based on the modified magnesium slag-based solid waste backfill material constructed by the storage, in order to explore the strength characteristics and carbonation depth evolution of the CO2 storage backfill material, the interaction between CO2 and the storage backfill material was analyzed from the perspectives of uniaxial compressive strength, carbonation depth test, pore structure distribution, microstructure and phase composition. The results show that carbonation can significantly improve the compressive strength of the storage backfill material, and the carbonation depth increases with the increase of carbonation time, and increases slowly after complete carbonation. The later the initial carbonation age, the faster the growth rate of compressive strength and carbonation depth, and the greater the growth rate. After high concentration CO2 curing, the diffusion rate and carbonation degree of the storage backfill material gradually decreased from the outside to the inside, and the calcium carbonate content also gradually decreased. The carbonation can significantly reduce the porosity of the sample, gradually transform from large pores to small pores, and the pore size distribution and pore structure are significantly improved. Therefore, the later the initial carbonation age is, the more beneficial the carbonation effect is for the long-term stability and air tightness development of the backfill material of the CO2 storage, which provides important theoretical guidance for the construction and storage method of the CO2 storage.

Green and efficient recovery of poly metals from converter sludge through reduction roasting and preparation of backfill from tailings

Converter sludge (CS) is a type of solid waste containing iron and poly metals that are not thoroughly utilized yet. A novel process combining reduction roasting with waste backfill was designed to optimize the recovery of poly metals and investigate the feasibility of waste tailings as mine backfill. The dust contained 66.57 % zinc oxide, which could be sold as a by-product to zinc smelters, with 92.65 % lead recovery and 95.36 % zinc recovery. The powdery reduced iron (PRI) was suitable for steelmaking, and 91.45 % of iron was recycled. During reduction, lead and zinc in CS were reduced and then volatilized, and iron recovery was enhanced by the formation and growth of metallic iron. The coarsening of metallic iron was dominated via surface and volume diffusion, and the average activation energy was 966.48 kJ/mol. The slump, yield stress, and 90-day compressive strength of the backfill prepared from tailings were 208 mm, 106 Pa, and 1.11 MPa, respectively, indicating that it could be used as the backfill for underground mined-out areas. This process presents excellent application prospects and provides innovative ideas for comprehensive and green disposal of CS.

Carbonation curing of modified magnesium-coal based solid waste backfill material for CO2 sequestration

CO2 sequestration is an effective method for dealing with the global climate crisis, and carbonation curing is considered an effective method of sequestering CO2 and improving the mechanical properties of cement-based materials (CBM). Regarding modified magnesium-coal based solid waste backfill material (MB), to explore its carbonation curing performance and CO2 sequestration capacity, its uniaxial compression strength (UCS), carbonation depth, microstructure, CO2 transport performance, CO2 uptake capacity, and carbonation efficiency are analyzed and characterized using UCS tests, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR) analysis. The results show that the early UCS of the MB is significantly improved by carbonation curing. The UCS at 7 days is 10.91 times higher than that of the MB without carbonation curing, and the UCS increases as the concentration and modified magnesium slag-based cementitious material (MC) content increase. Carbonation curing makes the microstructure of the MB significantly denser and reduces the porosity, pore diameter, and permeability. The formation of carbonated products such as calcium carbonate and hydration products makes the microstructure more compact, which is the main reason for the rapid increase in the early UCS of the MB. The maximum CO2 uptake capacity of the MB through carbonation curing is 14.3%, and the carbonation efficiency is up to 92.2%. Therefore, carbonation curing of MB has broad application potential in improving the UCS and sequestering CO2.

Research of the workability, mechanical and hydration mechanism of coal gangue-construction solid waste backfilling materials

In order to effectively address the issues of coal gangue emissions and the accumulation of construction solid waste, a combined treatment of coal gangue and construction solid waste can be implemented. In this study, a composite backfilling material was designed, with coal gangue and construction solid waste as the main aggregates. Through laboratory experiments, the time-dependent flow performance, mechanical properties, and microstructure of the material were analyzed under different proportions of factors including fly ash content, substitution rate of construction solid waste, mass concentration, and water reducing agent content. The research results indicate the following: The effects of reducing agent content, mass concentration, fly ash content, and substitution rate of construction solid waste on flow performance increased in that order. The addition of construction solid waste is negatively correlated with the strength of filling materials. The appropriate substitution ratios for FA, construction solid waste, mass concentration, and reducing agent were determined to be 21 %, 50 %, 80 %, and 0.6 %, respectively. The CH component in the material exhibited a trend of initially increasing and then decreasing, providing a large amount of reactants for secondary hydration reactions and strengthening the internal structure of the material. In the middle stage of hydration, FA and activators played an important role in the later stage by providing raw materials for secondary hydration, enriching the internal composition of the structure, and enhancing the backfilling performance of the backfilling material. This study can achieve the recycling and utilization of coal gangue and construction solid waste, and enhance the stability and bearing capacity of backfilling materials.

Mitigation of Mining Effects on the Environment

Editor’s note: The aim of the Geology and Mining series is to introduce early career professionals and students to various aspects of mineral exploration, development, and mining in order to share the experiences and insight of each author on the myriad of topics involved with the mineral industry and the ways in which geoscientists contribute to each. Abstract All human activities produce waste and affect our environment, including the solids and water involved during mining and metallurgical operations. The nature and characteristics of these impacts vary considerably depending on many factors, including the geology of the operation, type of mining and processing implemented, sensitivity of the local environment to the operation, and proximity to human settlements or sensitive environmental settings. Environmental challenges associated with mineral extraction and processing include impacts to land, air, water, soil, flora, fauna, and socioeconomic fabric. Mines can generate large land disturbances and can also result in sterilization of land through deposition of barren, nonreactive rock piles (termed waste) during production and after operation. Other mine waste piles can be chemically reactive and interact with precipitation and runoff, leading to metal and sulfate release into surface and ground water. Impacts on soils may result directly from weathering of mine waste or through interaction with affected waters. Interaction with the atmosphere may occur, with release of aerosol or airborne metals or minerals affecting air quality. In addition, the release of gases containing CO2, SOx, and NOx and halide gases can lead to acid rain or general lowering of air quality. These challenges can be predicted, quantified, and understood during the mine design and operations processes by application of geologic knowledge, geochemical and hydrogeological data, and mining experience. Such understanding can then identify appropriate solutions, including changes to operations through sequenced mining to reduce exposure of material with high metal or sulfide content; partial or full backfill of mine excavations; use of cemented waste backfill; modifications to water discharge designs; and treatment of water prior to discharge. A critical aspect of addressing environmental challenges and reducing environmental impact involves engagement with communities, government, and society. The confidence of society is essential to the delivery of long-term sustainable plans.

Coal Mine Solid Waste Backfill Process in China: Current Status and Challenges

Coal mine solid waste backfill is a coal mining method employed to safeguard subterranean and surface geological formations, as well as water resources, against impairment. It stands as a pivotal technical approach for realizing ecologically sustainable mining endeavors, aiming to address China’s predicament of ’three down’ coal pressure, coal gangue emissions, and land resource scarcity. This manuscript delves into an in-depth exploration of the evolution and research status pertaining to solid backfill technology, encompassing backfill materials, rock mechanics, backfill processes, and their application across China’s coal sector. The developmental challenges and technical intricacies linked to solid backfill technology within coal mines are meticulously scrutinized. Building upon these challenges and complexities, this study sets forth a progressive trajectory for solid backfill technology within the contemporary era. This trajectory envisions the synchronized advancement of novel solid backfill materials, intelligent surveillance and regulation methodologies, and machine learning technologies for backfill quality assessment. By doing so, the overarching aim of achieving superlative quality, heightened efficiency, and automation in solid backfill practices can be effectively realized.

Mechanical properties, pore characteristics and microstructure of modified magnesium slag cemented coal-based solid waste backfill materials: Affected by fly ash addition and curing temperature

The high-temperature, deep-well environment can affect the mechanical properties and long-term stability of modified magnesium slag cemented coal-based solid waste backfill material (MMS-CBM). The purpose of this study was to investigate the effects of fly ash addition (0 %, 10 %, 20 %, 30 % and 40 %) and curing temperature (20 °C, 30 °C and 40 °C) on the mechanical properties, pore characteristics and microstructure of MMS-CBM. Based on this, relevant laboratory tests (uniaxial compressive strength test, pore structure test and microstructure test) were conducted to characterize the influence mechanism of fly ash addition and curing temperature on the performance of MMS-CBM. The results show that the physical properties (uniaxial compressive strength, pore characteristics and microstructure) of MMS-CBM are significantly affected by fly ash addition and curing temperature. With the increase of fly ash addition, the number of active particles and hydration products involved in the hydration reaction gradually increased, and the physical properties of MMS-CBM were gradually optimized. With the increase of curing temperature, the hydration reaction rate and hydration reaction degree of MMS-CBM gradually deepened, which accelerated the volcanic ash reaction of fly ash particles, which had a promoting effect on the early intensity of MMS-CBM. However, the subsequent strength of MMS-CBM will be affected by thermal damage, resulting in deterioration of physical properties and seriously affecting the long-term stability of MMS-CBM. In addition, the porosity and fractal dimension of MMS-CBM are linearly related to the uniaxial compressive strength, indicating that the pore characteristics can reflect the mechanical properties of MMS-CBM. This study provides a theoretical reference value for the application of MMS-CBM in high-temperature deep wells.

The performance of construction waste backfilling subway depot—A case study in Zhengzhou

The construction of a large site section of the subway will lead to the demolition of large buildings and produce much solid waste. It wastes resources, increases construction costs, and seriously impacts the relevant national carbon emission targets. In order to solve the above problems, the compaction test, CBR test, compactness test, K30 test, and static load test were carried out in this study. This paper compares the performance difference between construction waste recycled material and traditional material and explores the application method of construction waste recycled material in subgrade backfilling. The ratio of brick concrete, moisture content, and particle level significantly influences the backfill performance. Test the proportion of brick concrete in construction waste 0:10, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, 10:0. The moisture content varies from 5% to 14%. The material was divided into three groups according to the particle size: passing 50 mm, passing 31.5 mm and passing 4.75 mm, and the particle grading design was carried out. The results showed that: when the particle size ratio of passing 50 mm, passing 31.5 mm and passing 4.75 mm is 100:90:45, the brick to total brick concrete is 50%. The moisture content is 12%, the characteristic value of subgrade bearing capacity can reach 400kPa, the strength is better than that of traditional backfill materials, and it meets the design requirements of each backfill area of the metro rolling stock section. In addition, ABAQUS software was used to simulate the load test and proposed a method to predict the foundation’s bearing capacity based on the recycled material’s performance parameters. This research is applied to the depot of Zhengzhou Metro Line 12 and provides a reference for the resource utilization of construction waste in the large site of the metro.

Basic characteristics of magnesium-coal slag solid waste backfill material: Part I. preliminary study on flow, mechanics, hydration and leaching characteristics

The environmental damage caused by surface subsidence and coal-based solid waste (CBSW) is a common problem in the process of coal mining. Backfill mining can control the mining-induced subsidence and solve the problem of bulk solid waste storage. In the present work, a magnesium-coal slag solid waste backfill material (MCB) with modified magnesium slag (MS) as binder and CBSW (fly ash (FA), flue gas desulfurization gypsum (FDG) and coal gasification slag (CGS)) as supplementary cementitious material/aggregate was proposed to meet the needs of coal mining in Northern Shaanxi, China, to realize the comprehensive treatment of goaf and CBSW. The results show that: (1) The rheological curve of the fresh MCB slurry is highly consistent with the Herschel-Bulkley (H–B) model, and its fluidity meets the basic requirements of mine backfill pumping. With the addition of FDG and MS, the yield stress, apparent viscosity and thixotropy of MCB slurry increase, while the pseudoplastic index and slump decrease. (2) The strength of MCB develops slowly in the early stage (0∼14 days) and increases rapidly in the later stage (14∼90 days). Except for the ratio of M20F1 and FDG = 0%, the strength of samples at other ratios (at 28 days) is between 6.06∼11.68 MPa, which meets the strength requirement of 6 MPa for coal mine backfill. The addition of MS and appropriate amount of FDG is beneficial to the development of strength. In contrast, MS exhibits a significant improvement in early strength, and FDG has a significant improvement in late-age strength. (3) Corresponding to the compressive strength, the hydration products C–S(A)-H and AFt of MCB are less in the early stage and greatly increased in the later stage. The active substance in FA/CGS will undergo pozzolanic reaction with the MS hydration product CH. The addition of FDG and MS can promote the reaction and increase the amount of hydration product, but in contrast, the promotion effect of FDG is more significant. (4) The amount of heavy metal leaching of MCB meets the requirements of national standards. The hardened MCB has a solidification/stabilization effect on heavy metal elements, which can significantly reduce the amount of heavy metal leaching. The results imply that MCB is a safe, reliable, and eco-friendly solid waste backfill material, and its application is conducive to the coordinated development of coal resource mining and environmental protection.

Study on Mix Proportion Optimization and Microstructure of Coal-Based Solid Waste (CSW) Backfill Material Based on Multi-Objective Decision-Making Model.

The preparation of underground-backfill material from CSW can be used for large-scale disposal of solid waste. The proportion of backfill material plays an important role in transportation and backfilling effect, and the mix-proportion optimization of backfill material is essentially a multi-factor and multi-objective optimization problem. In this paper, to obtain the mix proportion of backfill materials with optimal comprehensive-evaluation indexes, and suitable for the engineering application, the fluidity and strength of backfill material, mainly composed of coal gangue(CG), fly ash (FA), flue gas desulfurization gypsum (FGD gypsum), and gasification coarse slag (GCS), were tested by single-factor transformation method, and the effects of various solid wastes on the slump-flow, bleeding rate and early strength of backfill material were analyzed. The optimal mix proportion of CSW with the slump-flow, bleeding rate, and 3-day and 7-day strengths as the evaluation indicators is FA: GCS: FGD gypsum: CG = 25%:25%:25%:25%, according to the multi-objective decision model. Furthermore, the comprehensive evaluation index that meets the requirements of mine backfilling is obtained by changing the ordinary portland cement (OPC) content, that is, the optimal OPC content is 10% of the total solid waste, and the mass concentration is 78%. Finally, the pore structure, micromorphology, and composition of the backfill material with the optimal mix proportion were studied by Mercury Intrusion Porosimetry (MIP), X-ray Diffraction (XRD), and Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS). The research results provide a good reference for the field application of CSW for underground backfilling.

Effect of polypropylene fiber on properties of modified magnesium-coal-based solid waste backfill materials

Driven by the “dual carbon” goal, modified magnesium-coal-based solid waste backfill materials (MFPB) were gradually used in backfill mining instead of traditional backfill materials. To study the effect of polypropylene (PP) fibers with different contents and lengths on the properties of MFPB, slump tests, rheological tests, uniaxial compressive strength (UCS) tests, permeability tests, and scanning electron microscopy were carried out. The results showed that with the increase in the PP fiber content and length, the flowability of the MFPB characterized by the slump and rheological parameters deteriorated, but the UCS increased significantly, and the permeability first decreased and then increased. The mutual entanglement of PP fibers was the main reason for the poor fluidity of the MFPB. The PP fibers could effectively enhance and improve the strength and toughness of the MFPB by an anchoring effect and irregularly distributed network structure. The strengthening effect mainly occurred in the medium and long term, and the early strengthening effect was not evident. After curing for 28 d, the maximum growth rate of the UCS was 62.5%. After loading failure, the MFPB containing PP fibers still had good integrity and continuity, and there was no shedding phenomenon. The network structure that formed in the early stage due to the PP fibers did not easily segregate and precipitate. The transmission channels between the PP fibers connecting holes were the main reason that the MFPB permeability first decreased and then increased. Therefore, this study can provide a reference for the application of PP fibers to MFPB. Enhancing the performance of the backfill body has important theoretical and practical significance for the development of mine backfill.

Control effect of coal mining solid-waste backfill for ground surface movement in slice mining: a case study of the Nantun Coal Mine.

Management of solid waste and protecting the ecological balance of the region are key challenges that the coal mining industry has to face. This study evaluated the effect of solid waste backfilling mining on the overlying strata movement and surface deformation variation pattern in slice mining. The mechanical characteristics of different cemented paste backfills (CPB) were compared. The CPB specimens were made of coal gangue and cement with or without the addition of fly ash. The experiments showed that the mechanical strength of the CPBs made of coal gangue and cement increased dramatically. A numerical simulation was then performed to analyze the variation patterns of the overlying strata displacement and surrounding rock stress distribution before and after filling the 3lower and 3upper coal seams with CPB. The CPBs reduced the movement of the surface by 95.1% and 95% during the mining of the 3lower and 3upper coal seams, respectively. Finally, we used a mining-induced subsidence prediction and analysis system to predict the influence of the 3lower and 3upper coal seams on the ground surface subsidence. It was found that the ground surface subsidence induced by CPB mining was 1/20 that of the cumulative ground surface subsidence caused by caving mining. CPB mining could effectively control the ground surface subsidence caused by multi-slice mining of the thick coal seam, offering protection for buildings above the ground. Our research provides theoretical and technical support for coal mining under buildings subjected to similar conditions.