Backfill Mining Research Articles

Corrigendum: Characterization of strength and quality of cemented mine backfill made up of lead-zinc processing tailings

Corrigendum: Characterization of strength and quality of cemented mine backfill made up of lead-zinc processing tailings

Transport mechanism and control technology of heavy metal ions in gangue backfill materials in short-wall block backfill mining

Short-wall block backfill mining can effectively control the movement of overlying strata, prevent water loss and utilize waste gangue materials. However, heavy metal ions (HMI) of gangue backfill materials in the mined-out area can be released and transported to the underlying aquifer, causing pollution of water resources in the mine. Accordingly, with short-wall block backfill mining technology, this study analyzed the sensitivity of gangue backfill materials to the environment. The pollution mechanism of gangue backfill materials to water resources was revealed, and the transport rules of HMI were explored. The regulation and control methods of water pollution in the mine were then concluded. The design method of backfill ratio for comprehensive protection of overlying and underlying aquifers was proposed. The results show that the release concentration of HMI, the gangue particle size, the floor lithology, the burial depth of the coal seam, and the depth of the floor fractures were the main factors that affected the transport behaviors of HMI. After long-term immersion, HMI of gangue backfill materials underwent hydrolysis and were released constantly. HMI were subjected to the coupled action of seepage, concentration, and stress and then driven by water head pressure and gravitational potential energy to transported downward along the pore and fracture channels in the floor with mine water as the carrier. Meanwhile, the transport distance of HMI increased with increasing release concentration of HMI, the permeability of the floor stratum, and the depth of floor fractures. Still, it decreased with increasing gangue particle size and the burial depth of the coal seam. On that basis, external-internal cooperative control methods were proposed to prevent the pollution of gangue backfill materials to mine water. Furthermore, the design method of the backfill ratio for comprehensive protection of overlying and underlying aquifers was proposed.

Acoustic emission characteristics and failure prediction of defective cemented gangue-fly ash backfill under seepage-stress coupling

ABSTRACT Aiming at the problem of seepage-stress coupling failure instability of cemented gangue-fly ash backfill (CGFB) with defects, the triaxial compression test and acoustic emission (AE) monitoring test of the CGFB were carried out in this paper. The strength characteristics of defective CGFB under seepage-stress coupling were analysed，the variation rules of AE parameters (ring count, b-value and entropy value) in the failure process were systematically studied. It is found that the AE parameters (ring count, b-value, and entropy value) of backfill with defects under seepage-stress coupling have a ‘mutation’ phenomenon, which can be used as a precursor feature of failure instability of backfill. Combined the grey-cusp catastrophe theory, a failure prediction model of backfill based on AE parameters (ringing count) was established, and the seepage-stress coupling fracture of backfill with defects was effectively predicted, indicating that the model is feasible to predict the seepage-stress coupled failure of backfill with defects. The research results can provide a theoretical basis for stability monitoring and failure prediction of backfill in deep water-rich mines in China.

Advantages of Backfill Mining Method for Small and Medium-Sized Mines in China: Safe, Eco-Friendly, and Efficient Mining

Despite China’s position as a global mining powerhouse, tens of thousands of small- and medium-sized mines (SM mines) within the country continue to pose potential safety hazards and environmental pollution risks. Only through the identification of suitable development paths can these mines improve their economic and environmental benefits, ultimately driving significant progress in China’s mining industry. Backfill mining, an environmentally friendly mining method, has emerged as a viable solution, offering the potential to ensure mining safety, reduce environmental pollution stemming from tailings stockpiles, and enhance ore resource recovery. This review article aims to provide researchers and readers with a comprehensive understanding of the current situation and challenges faced by SM mines in China. It explores the mining processes, technologies, and equipment commonly employed by these mines while addressing the specific problems and challenges they encounter. Furthermore, the article offers recommendations to guide the future development of SM mines. Additionally, the review examines the prospects and potential applications of backfill mining methods within the context of SM mines in China, emphasizing their role in promoting sustainable mining practices, environmental protection, and waste utilization. Ultimately, this comprehensive review article serves as a valuable resource, stimulating discourse and encouraging experts and scholars to further explore the unique challenges and opportunities associated with SM mines. By highlighting the significance of green mining practices, environmental protection, backfill mining, and waste utilization, the article aims to inspire innovative solutions and foster sustainable practices within the Chinese mining industry.

Control of surface deformation and overburden movement in coal mine area by an innovative roadway cemented paste backfilling method using mining waste

Caving mining method could lead to massive waste rocks hauled to surface while leaving a large void in underground. This would eventually result in the surface subsidence and damage to the environment and surface infrastructures. In this study, we proposed three different backfilling methodologies to minimise the surface subsidence being 1) 100 % mining and 100 % backfilling (method 1); 2) leaving one slice of coal between two backfilled slices (method 2) and 3) leaving one slice of coal between one backfilled slice (method 3). The backfilling materials are made of waste rock, fly ash and cement and the optimal ratio has been found through the test program designed based on the orthogonal experiment design method. The strength of the backfilling paste is 3.22 MPa at the axial strain 0.033. The mine scale numerical simulation has also been conducted and it was concluded that the method 1 would lead to 0.098 m roof deformation in underground roadway whereas the method 2 and method 3 only induced a roof deformation around 32.7 % and 17.3 % of that induced by the method 1, respectively. All three methodologies have been approved to minimise the roof deformation and disturbance to the rock by mining operations. At last, the surface subsidence has been scientifically evaluated based on the probability integration method of surface movement. It indicated that the surface subsidence, horizontal movement, inclined movement and curvature of rock surrounding the panel void were all below the minimum value required by regulation. This confirmed that the selected backfilling mining is able to ensure the integrity of the surface infrastructures. This technology provides a new way to control the surface subsidence caused by coal mining.

A new acoustic emission characteristic parameter can be utilized to evaluate the failure of cemented paste backfill and rock combination

In backfill mining, there is a phenomenon of the joint bearing of cemented paste backfill and rock, so it is essential to study the destabilization damage mechanism of cemented paste backfill and rock combination (BRC). This study aimed to improve the evaluation system for the instability failure of BRC. A new evaluation index, Dr, based on acoustic emission (AE) characteristic parameters was proposed for predicting BRC instability failure caused by the load. This index comprehensively considers the time dependence and interaction of the AE rise time, amplitude, and average frequency during BRC failure. The study conducted uniaxial compression and simultaneous AE experiments for various ratio combinations of BRC to obtain the AE rise time/amplitude (RA) and average frequency (AF) values of BRC. Then, the RA/AF values were numerically calculated with fractal theory to obtain the Dr index, and the intrinsic relationship between Dr and BRC instability failure was further discussed. Finally, the index was validated through comparison with the statistical index b-value based on AE amplitude, and a discrimination criterion for BRC instability failure was proposed. The results show that: After reaching the yield stress, the number of AE events of the rock gradually decreases. In contrast, the number of AE events of the CPB fluctuates in the high-level range. The cement-tailings ratio significantly affects the BRC AE frequency and amplitude distribution. The decrease of the cement-tailings ratio enhanced the high-frequency amplitude signal of CPB, while weakening the medium and high-frequency amplitude signal of rock. The sudden drop of Dr in the near-failure stage can be used as a criterion for BRC failure determination. Compared with the b-value, using Dr as an evaluation index to predict BRC failure can obtain a slightly conservative result. The research provides a new and effective method for evaluating BRC instability failure, which can be used for real-time prediction of BRC instability failure in mining engineering practice.

Experimental study on evolutive fracture behavior and properties of sulfate-rich fiber-reinforced cemented paste backfill under pure mode-I, mode-II, and mode-III loadings

Tensile and shear fracture behaviors of fiber-reinforced cemented paste backfill (FRCPB) play critical roles in the safe and cost-effective engineering design of underground mine backfill structures. Sulfate pore solution is a key factor affecting the time-dependent evolution of fracture behavior and properties of FRCPB. However, no studies have been carried out to systematically investigate its effects on the fracture behavior and properties of mine backfill used in underground mines. The objective of this study is to discover the effect of sulfate concentration (0, 5000, 15,000, and 25,000 ppm) on FRCPB's fracture behavior and properties at different curing times (3, 7, 28, and 90 days) and under pure mode-I, mode-II, and mode-III loadings. The results show that, except for the 3-day FRCPB, the increase in sulfate concentration can continuously improve pre-peak stiffness and peak fracture resistance force and significantly enhance the post-peak residual resistance, especially under mode-III loading. Moreover, fracture energy shows a higher sensitivity to the sulfate concentration with respect to fracture toughness and stiffness. Furthermore, sulfate concentration has a very limited effect on tensile crack trajectory under mode I loading, while a transition of shear cracks from a curved crack pattern to a sharp and straight one is detected under mode II and III loadings. In addition, the fracture toughness possesses a stronger correlation with material stiffness and thus is recommended for the design of FRCPB to offer a more effective immediate support to surrounding rock. The obtained results provide an in-depth insight into the sulfate-induced evolution of fracture behavior and properties of FRCPB under various loading conditions and thereby promote the safe implementation of mine backfill technology.

Strength, Deformation Behavior, and Microstructure of Cement Paste Backfill with Calcium Chloride in Subzero Environments

This manuscript presents and discusses the results of an experimental study on the deformation behavior, strength, and microstructural development of cemented paste backfill (CPB) with chloride-bearing antifreeze (calcium chloride, CaCl2) in subzero environments. CPB samples with CaCl2 at various concentrations (0, 5, 15, and 35 g/L) were cured at different subzero temperatures (−1, −6, and −12°C) that represent temperatures to which CPBs may be exposed in mines located in permafrost or cold regions. Unconfined compressive strength (UCS) tests were conducted after specific curing time (7, 28, 60, and 90 days). Moreover, microstructural analyses and monitoring experiments (for volumetric water content and matric suction) were performed. The results showed that the addition of calcium chloride antifreeze reduced the strength of CPB and had a significant impact on its stress–strain behavior and microstructural characteristics. Furthermore, it was also found that the strength of CPB decreased with an increase of calcium chloride concentration and subzero curing temperature. These findings provide important guidance for mine backfilling work of CPB with chloride-bearing antifreeze additives and productivity improvement in subzero environments.

Application of deep neural network in the strength prediction of cemented paste backfill based on a global dataset

With the development of the mining industry, the increasing global content of tailings is causing environmental pollution and the use of tailings as a cemented paste backfill (CPB) for underground filling is an effective method of disposal. The application of the backfilling mining method is heavily dependent on the stability of the CPB. However, experimentally evaluating the unconfined compressive strength (UCS) of CPB is time-consuming and expensive. This study discussed the feasibility of using a deep neural network (DNN) model to predict the UCS of CPB. This study established the first global dataset of UCS values of CPB through a literature search and laboratory studies, for the first time. The dataset comprised 986 CPB samples, where each sample included 14 feature values and a target value. The dataset was divided into three parts, i.e., a training set, a validation set, and a testing set, which were used to build, validate, and test the model. The correlation coefficient (R), coefficient of determination, mean absolute error, and mean square error metrics were used for model evaluation. After the hyper-parameter tuning, the number of layers in the DNN model was 4, the learning rate was 0.001, and the dropout rate was 0.25. The optimal DNN model achieved excellent predictive performance on this dataset, with R values on the training, validation, and testing sets of 0.989, 0.964, and 0.967, respectively. The feature importance was analyzed using permutation importance and the Shapley Additive Explanation value, with the cement–tailings ratio found to be the most important feature value with the greatest impact on the model output. This study provides, for the first time, a UCS prediction based on the global CPB dataset, a method that can quickly and accurately obtain the UCS of CPB. The method can save a lot of experimental time and provide a theoretical reference for subsequent environmental management as well as tailings utilization, and promotion of paste filling.

Mechanical properties and leaching behavior of modified magnesium slag cemented aeolian sand paste backfill materials

Magnesium slag is a by-product of magnesium smelting industry, and its massive discharge has seriously threatened human health and ecological environment. In order to solve the environmental problems caused by magnesium slag, a mine backfill material (MFPB) was prepared with modified magnesium slag-fly ash cemented aeolian sand in this paper, and the long-term mechanical properties and leaching behavior of MFPB were investigated. The strength of the MFPB increased with increasing curing time, and the strength reached 4.984–17.140 MPa at 300 d, with FA20 having the highest strength. In terms of environment: (1) Except that FA has certain risks, the leaching levels of other raw materials meet the class III groundwater standard (III-GQSL) in GB/T 14848–2017. (2) The leaching level of MFPB based on the SPLP procedure meets the III-GQSL, and has a significant stabilization/solidification effect on hazardous elements; (3) The results of the LEAF test showed that pH and liquid–solid ratio were important factors affecting the leaching of harmful elements in MFPB. MFPB has good mechanical properties and environmental friendliness, and has the potential for large-scale safe application in mine backfilling.

Multi-criteria comparative analysis of the pressure drop on coal gangue fly-ash slurry at different parts along an L-shaped pipeline

Disposing of coal gangue and fly-ash on the surface is a risky method with tremendous potential catastrophic consequences for the environment. Backfill mining is a promising practice for turning those hazardous wastes into functional backfill materials. Unfortunately, how to efficiently deliver the slurry to the desired places remains under-researched. To address this issue, the computational fluid dynamics software Fluent was used in the current study in addition to a laboratory rheological test to simulate the impact of various parameters on the evolution of pressure at a particular section of the pipeline. Furthermore, the response surface method was employed to investigate how the various components and their corresponding influencing weights interact to affect the pressure drop. This study demonstrates that the pressure drop of the slurry is highly influenced by slurry concentration, speed, and pipe diameter. While conveying speed is the main component in the bend section, pipe diameter takes over in the horizontal and vertical pipe sections.

Proportion optimization and strength prediction of CGS backfill materials based on GA-ELM mode

ABSTRACT The strength of the backfill body is an important aspect of safe production in backfill mining technology. In order to quickly and accurately obtain the strength of coal gasification slag -based cemented backfill materials with different ratios, the orthogonal design of 4 factors and 5 levels and variance analysis method were used to study the mass concentration (A), coal gasification slag (CGS)/cement (B), bone glue ratio (C), activator content (D) on the compressive strength of backfill body and a genetic algorithm with 28-day compressive strength of CGS-based backfill material as the response value was constructed, and verify the applicability of the model. The results show that: the primary and secondary factors affecting the 28-day compressive strength are C > A > B > D, the optimal ratio is 80% mass concentration, CGS/cement ratio 4:1, bone glue ratio 3:7, and activator 3%, according to orthogonal variance analysis; the activity of CGS is gradually stimulated as the curing age grows, the hydration products Ettringite and C-S-H are continually generated, and the compressive strength of the backfill material increases in tandem; In the GA-ELM model test set, the intensity correlation coefficient between the prediction and the measured value reached an average of 0.99, and the prediction accuracy was 71.8% and 43.5% higher than that of ELM and PSO-ELM respectively; Laboratory studies have shown that the GA-ELM prediction model has a prediction accuracy of 98.2% and that it can accurately estimate the strength of CGS cemented backfill.

Study on dynamic adsorption characteristics of gangue to heavy metals in goaf and its water purification mechanism under leaching condition

Arid and semi-arid mining areas in Western China are faced with the problems of water shortage, large water inflow of mines and high-salinity of mine water. When the broken gangue is backfilled to the goaf by the solid backfilling mining technology, a large number of voids between the blocks is generated, which can store groundwater and purify water quality. In this study, the real void structure of the gangue backfilling body in the goaf was obtained through CT scanning. By using the COMSOL numerical simulation software, a coupling model of Free and Porous Media Flow and Transport of Diluted Species in Porous Media was established. From the mesoscopic void scale, the effects of particle size distribution, inflow velocity and ion concentration on the flow field characteristics, ion migration and dynamic adsorption characteristics of gangue in the leaching column were explored, and the purification mechanism of broken gangue to heavy metals in mine water was revealed. The results show that: (1) The larger the gangue particle size gradation, the larger the void size, the higher the velocity in the void, and the more significant the average flow velocity difference between the void area and the gangue area. With the increase of inflow velocity, the average velocity in the gangue area and void area also increases, but the average flow velocity in the void area is 5.36 times that in the gangue area; (2) Both the larger particle size gradation of gangue, higher inflow velocity and inlet concentration can improve the velocity of the ion migration in gangue leaching column; (3) The greater the inlet concentration, the faster the flow velocity, the higher the total adsorption rate of gangue in the leaching column; (4) Both decreasing the particle size gradation of the gangue and increasing the inlet concentration can increase the total adsorption capacity of gangue in the leaching column; (5) The removal of heavy metals by gangue is the result of physical adsorption, ion exchange and other reactions. The research results can provide theoretical reference and data support for the treatment of high-salinity mine water in mining areas of Western China.

Preparation and strength mechanism of slag-based mine backfill for low concentration ultra-fine tailings

High concentrated ultra-fine tailings have been cemented using various methods and used as the backfill material, whereas the suitable cementitious material formulations for the low concentrated ultra-fine tailings (LUFTs) with a solid content ≤ 55% have not been presented. For the purpose of utilizing the LUFTs in practice, this study presented a binder formulation for cementing the LUFTs; the cementitious material is alkali-sulfate-activated slag, and some amounts of ordinary Portland cement were added as a reinforcing agent to improve the properties of cemented LUFTs. The results showed that a binder with 61.3% GBFS, 20.0% cement, 15.1% anhydrite, and 0.5% alkaline activator (in which 50% for both quicklime and sodium metasilicate nine-hydrate), a binder to tailing ratio of 1:8, and a tailing slurry concentration of 55% exhibited the highest strengths in 3d, 7d and 28d, respectively 0.62 MPa, 0.93 MPa, and 1.41 MPa. Moreover, based on the XRD, TG, and SEM analysis, the compressive strength mainly originates from the reticular skeleton structure formed by the hydration product such as C-S-H gels and ettringite.

Microstructure and mechanical behavior of cemented gold/tungsten mine tailings-crushed rock backfill: Effects of rock gradation and content

Without appropriate and responsible waste management in place, the cursory storage of tailings and waste rocks on the surface can cause devastating damage to the planet's ecosystems. To proactively manage or abolish the damage, some techniques such as mine backfill have been already used repeatedly in mines. Microstructure and strength behavior of cementitious tailings-crushed rock backfill (CTCRB) with gold/tungsten tailings and rock contents (e.g., 10%, 20%, 30%, 40%, and 50%) were conducted in this study by using both UCS (unconfined compressive strength) tests (e.g., peak strengths, stress-strain curves, failure modes) and SEM micro-graphs. Key conclusions were shown that: when gradation and content of crushed rock was considered as 1–3 mm and 50% respectively, the UCS value of gold tailings based backfills was 1.02 MPa. In contrast, the UCS value of tungsten mine tailings based backfills was 1.36 MPa when the amount of crushed rock within the filling matrix became 10%. Tungsten tailings based backfills were more sensitive to crushed rock gradation than gold tailings based backfills. CTCRB's stress-strain curvatures were up-concave in the step of pore compaction. With the increase in the content and gradation of crushed rock, tungsten tailings based backfills showed swelling and crushing in complete destruction. Tailings' particle size, crushed rock content and gradation utterly affected the failure modes of CTCRB. Ettringite/CSH gel was found to be the leading hydration materials in the backfill matrix. The micro-cracks within CTCRB specimens were unfavorably correlated with its UCS data. To conclude, this study's main outcomes could give a significant guide for CTCRB's industrial uses.

An experimental study on the mechanical properties of underground mining backfill materials obtained from recycling of construction and demolition waste

Environmental and safety factors have caused the mining industry to consider backfilling underground openings to prevent mine collapse in deeper and further extraction operations. This paper discusses the possibility of utilizing the construction and demolition waste (CDW) as cemented recycled aggregate backfill (CRAB) materials in the underground mining industry. In this regard, several samples were prepared by mixing the recycled aggregates of CDW components and Portland cement and various tests were performed to consider their physical and mechanical properties. Results indicate that by adding 8% cement content to the mixture, the uniaxial compressive strength (UCS), the most important property of backfill materials, reaches 4.95 MPa. Based on common compressive strength criteria of backfill materials, the obtained value of UCS satisfies the prerequisite for most underground mining applications. There are situations, such as the ground support, where higher UCS quantities are required for backfill materials. By removing the plaster and soil components of CDW from the mixtures, the compressive strength of samples has increased by 55.4% and 7.1% respectively. Therefore, by removing the plaster from the mixture, the prepared samples meet the requirements of ground support applications. Moreover, with the increase in cement dosage, the effects of cement content on the properties of the CRAB samples were investigated.

Preparation and Characterization of Low-Carbon Cementitious Materials Based on Soda-Residue-Activated Ground Granulated Blast-Furnace Slag: A Case Study on Cemented Paste Backfills

To investigate the issues related to significant environmental damage and poor resource utilization of soda residue (SR), the composition and microstructure of hydration products of the GGBS (ground granulated blast-furnace slag) synergistically activated by NaOH-SR are characterized by an X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), thermogravimetric–differential thermogravimetric (TG-DTG) analysis, and scanning electron microscope X-ray energy dispersive spectrometry (SEM-EDS). The effect of SR proportion, activator dosage, and water-to-binder ratio on the hydration process is studied. Results indicate that the hydration products mainly include hydrated calcium chloroaluminate (3CaO·Al2O3·CaCl2·10H2O, FS), hydrated calcium aluminosilicate (Ca2Al3(SiO4)3OH, C-A-S-H), halite (NaCl), calcite (CaCO3), and C-S-H gel. With the increase in SR proportion (especially from 80% to 90%), the C-S-H gel yield decreases significantly, while the FS yield rapidly increases, and the T-O-Si (T = Al or Si) peak shifts to a higher wavenumber range (955 cm−1 to 975 cm−1). With the decrease in activator dosage (40% to 15%), the hydration reaction gradually weakens, and the FTIR band of the T-O-Si (T = Al or Si) shifts to the lower wavenumber range (968 cm−1 to 955 cm−1). Then, cemented paste backfills (CPBs) are prepared with iron tailings as the aggregate. At mass content of 75%, SR proportion of 80%, and activator dosage of 30%, the fluidity of the CPB reaches 267.5 mm with a 28-day unconfined compressive strength (UCS) of 2.4 MPa, confirming that SR- and NaOH-synergistically-activated GGBS has great application prospects in backfill mining.

The Application of Fuzzy Mathematics in the Optimization of the Recipe of Filling Paste for Coal Mine Backfill

Backfill is a very important technology that can be used to reduce the environmental footprints resulting from coal mining. The selection of proper filling materials is of great significance to the operation cost and the stability of the goaf. This paper investigated the feasibility of using the coal gangue as the main component of the filling paste so as to reuse the byproducts in coal mining to the maximum extent. The filling pastes were composed of coal gangue as the aggregates, cement or gypsum as cementitious materials, and some additives. In order to determine the optimal recipe, the performances of filling pastes were first comprehensively evaluated according to their fluidity, mechanical properties, shrinkage, and permeability. The results showed that cement content was the most influential factor, while the fly ash addition was the weakest factor for the performance of filling pastes. Moreover, the appropriate use of a water reducer and expansion agent improved the working performance of the paste. Based on the performances of filling pastes, the fuzzy mathematics evaluation method was then used to establish the weight vector and index vector. The principle of maximum membership degree and the principle of maximum closeness were used to identify the identified objects and find the best recipe for the filling paste. The results showed that this evaluation method could fully reflect the influence of various factors and provide accurate evaluation results.

Geotechnical modeling of the method for mining cobalt deposits at the Bou Azzer Mine, Morocco

Purpose. The Bou Azzer Mine encounters difficulties during cobalt mining. In order to select the optimal mining sequence with the least geotechnical stability problems, one possible variant is the cut and backfill mining method used in the Bou Azzer East area at a depth of 540 m. Methods. This paper presents a methodology for selecting a sequence of the cut and backfill mining method using 2D geotechnical numerical modeling, taking into account the morphological characteristics, geomechanical properties of the ore and the surrounding rocks. Findings. The sequences of mining with rock backfill and rock-cemented backfill show that the high principal stress (Sigma 1) is in the range of 10-153 MPa, and the safety factors are in the range of 0.63-1.89. Therefore, mining sequences with cemented backfill and under cemented backfill have a principal stress (Sigma 1) in the range of 10-112 MPa and acceptable safety factors. Originality. In this study, the bottom-up mining sequence with a cemented backfill is proposed for the case of low-quality serpentine footwall. This mining sequence aims to achieve good cobalt mine production and provides a safe environment for miners. Practical implications. In the mining industry, the choice of mining method using 2D or 3D geotechnical numerical mo-deling is important to ensure the safest and most operational mining sequence in the mine lifetime.

Investigating the synergistic effects of magnesia-coal slag based solid waste cementitious materials and its basic characteristics as a backfill material

Applying solid waste resources as backfill material can reduce both the cost of backfill and the environmental problems caused by solid waste landfills. In this paper, the synergistic reaction effects of solid waste modified magnesia slag (MMS), coal gasification slag (CGS), and desulfurized gypsum (DG) as magnesium-coal slag based cementitious materials (MCC) and their preliminary feasibility as mining cementitious materials in synergy with coal gangue for the preparation of backfill materials are investigated. The results show that the order of the compressive strength of the cementitious systems is ternary system > binary system > monolithic system, which proves the existence of synergistic effect among MMS, CGS, and DG and determines the optimal dosing of each raw material in the ternary system. At early ages, the physical effect of CGS and the chemical effect of DG in the ternary system can promote the hydration reaction of MMS, but the synergistic effect between the three is weak; At later ages, a synergistic effect occurred among silica-aluminate depolymerization in CGS, dissolved sulfate from DG and hydration products from MMS, which promoted the production of more hydration products calcium-silicate(aluminum)-hydrate (C-S(A)-H) and AFt, and improved the compressive strength. In addition, the strength, fluidity and leaching of the backfill material prepared by MCC in collaboration with coal gangue can meet the preliminary feasibility for mine backfill. In the present work, the full solid waste MCC is developed to completely replace cement and use it to prepare backfill materials, which is of great importance to the comprehensive utilization of bulk solid waste, the reduction of backfill costs, and the enhancement of the economic and ecological interests of mines.