It’s a universal engineering problem to seal micro-cracks of low-permeability argillaceous rock mass by grouting in the fields of civil engineering and mining. This paper achieved the grouting sealing of low- permeability artificial rocks with the permeability of 0.1–40 mD by adopting silica sol imbibition grouting. The variation characteristics of particle size, viscosity, and contact angle of silica

To investigate the failure process and characteristics of D-shaped tunnels under different maximum principal stress directions θ, true-triaxial tests were conducted on cubic sandstone samples with a through D-shaped hole. The test results show that the failure process can be divided into 4 periods: calm, buckling deformation, gradual buckling and exfoliation of rock fragment, and formation of a V-shaped

Slope stability prediction research is a complex non-linear system problem. In carrying out slope stability prediction work, it often encounters low accuracy of prediction models and blind data preprocessing. Based on 77 field cases, 5 quantitative indicators are selected to improve the accuracy of prediction models for slope stability. These indicators include slope angle, slope height, internal friction

To solve the energy consumption and CO2 emission during cement production, the new binders must be developed as an alternative to cement. CaO/CaSO4-activated slag binder is an eco-friendly and safe cementitious material; however, its low strength during initial stages limits its applications. In this study, colloidal nanosilica (CNS) was employed as an additive to improve the strength of CaO/CaSO4-activated

In this paper, the cyclic constitutive equations were proposed to describe the constitutive behavior of cyclic loading and unloading. Firstly, a coupled damage variable was derived, which contains two parts, i.e., the compaction-induced damage and the cracking-induced damage. The compaction-induced damage variable was derived from a nonlinear stress–strain relation of the initial compaction stage,

Materialization of coal is one of effective and clean pathways for its utilization. The microstructures of coal-based carbon materials have an important influence on their functional applications. Herein, the microstructural evolution of anthracite in the temperature range of 1000–2800 °C was systematically investigated to provide a guidance for the microstructural regulation of coal-based carbon materials

The stress concentration and failure at chamber intersections in coal mine are intense, especially in deep-buried, super-large section conditions. In this paper, the plastic radius of super-large section chamber under unequal pressure was corrected on the basis of the size effect. Then, stress and failure evolution of intersections under different crossing angles and equivalent angular bisectors were

In this study, chalcopyrite was oxidized in hydrogen peroxide (H2O2) solutions of different concentrations to simulate different degrees of oxidation in real ores, and the effects of H2O2 treatment on chalcopyrite surface properties and flotation performance were investigated by surface analysis techniques and floatation experiments, which implied the reason for the poor grade and recovery of oxidized

Malachite is one of the main minerals used for the industrial enrichment and recovery of copper oxide resources, and copper ions are unavoidable metal ions in the flotation pulp. The microflotation, contact angle, and adsorption experiments indicated that pretreatment with an appropriate concentration of copper ions could improve the malachite recovery, and the addition of excess copper ions reduced

Borehole breakout is a widely utilised phenomenon in horizontal stress orientation determination, and breakout geometrical parameters, such as width and depth, have been used to estimate both horizontal stress magnitudes. However, the accuracy of minimum horizontal stress estimation from borehole breakout remains relatively low in comparison to maximum horizontal stress estimation. This paper aims

Resistivity will have different response characteristics to the hydraulic fracture propagation process. In this work, a resistivity testing system for hydraulic fracturing specimens was established. Resistivity and acoustic emission (AE) information were jointly analysed to determine the dynamic response characteristics of resistivity during hydraulic fracture propagation. The results show that the

The constant mi in the Hoek-Brown (H-B) criterion is a fundamental parameter required for determining the compressive strength of rock. In this paper, drilling parameters provide a new basis for determining the constant mi. An analytical relationship between the drilling parameters and constant mi is established in consideration of the contact response between the drilling bit and the cut rock in the

Due to the complexity of the real engineering environment, the arrival measurement inevitably contains outliers and leads to serious location errors. In order to eliminate the influence of the outliers effectively, this paper proposes a novel robust AE/MS source localization method using optimized M-estimate consensus sample. First, a sample subset is selected from the entire arrival set to obtain

Pyrrhotite is an associated mineral that exists widely in sulfide ore. The presence of pyrrhotite will affect the recovery of platinum group minerals. Therefore, researchers have paid increasing attention to the flotation separation of pyrrhotite. Pyrrhotite superstructures owning different Fe/S ratios results in various crystal structures, corresponding to different physical, chemical and electronic

Filled inclusions in rock discontinuities play a key role in the mechanical characteristics of the rock and thereby influence the stability of rock engineering. In this study, a series of impact tests were performed using a split Hopkinson pressure bar system with high-speed photography to investigate the effect of interlayer strength on the wave propagation and fracturing process in composite rock-mortar

Abstract not available

The utilization of Ca ion as assistant depressant of CMC on talc has been widely reported. Thus, the study on the adsorption mechanism of Ca ion on talc surface is very crucial for understanding the performance of CMC on talc depression. In this paper, mechanism insights into hydrated Ca ion adsorption on talc (0 0 1) basal surface were creatively provided using DFT calculation. [Ca(H2O)6]2+ and [Ca(OH)(H2O)3]+

It has become an inevitable trend of human development to seek resources from the deep underground. However, rock encountered in deep underground engineering is usually in an anisotropic stress state (σ1 > σ₂>σ3) due to the influences of geological structures and engineering disturbances. It is therefore essential to study the mechanical, seepage, and dynamic disaster behaviors of deep rock under true

Recently a new grout material called WIS was invented for sealing water inflow in tunneling and underground constructions. In this study, a special experimental method called Intubated Counter Grouting (ICG) was proposed to investigate the influence of water dispersion on the rheological properties of the grout during the grouting process, and to testify the sealing performance of the grout, such as

This paper develops a model that only requires two sets of small-size rock specimens with the ratio of the structural geometry parameter maximum to minimum ae,max:ae,min ≥ 3:1 to determine the rock fracture and strength parameters without size effect and predict the actual structural performance of rock. Regardless of three-point-bending, four-point-bending, or a combination of the above two specimen

A large number of studies have shown that oolitic hematite is an iron ore that is extremely difficult to utilize because of its fine disseminated particle size, high harmful impurity content and oolitic structure. To recover iron from oolitic hematite, we developed a novel multistage dynamic magnetizing roasting technology. Compared with traditional magnetizing roasting technologies, this novel technology

The disintegration of granite residual soil is especially affected by variations in physical and chemical properties. Serious geologic hazards or engineering problems are closely related to the disintegration of granite residual soil in certain areas. Research on the mechanical properties and controlling mechanisms of disintegration has become a hot issue in practical engineering. In this paper, the

Rock joints exhibit hysteresis shearing behavior and produce energy dissipation under shear cyclic loads, which however cannot be accurately depicted by existing constitutive models. This paper establishes a constitutive model for hysteresis shearing and associated energy dissipation of rock joints. Analytical expressions of the model during cyclic shearing processes are derived. Derivation of the

In order to control the large deformation of tunnel surrounding rock, a new energy-absorbing bolt is developed. This bolt can be transformed into a rigid support when the deformation of the surrounding rock reaches the length of the sleeve tube, thus preventing the surrounding rock from continuing to deform. Moreover, this bolt has a simple structure and is easy to manufacture and assemble. Then the

As underground excavations are getting deeper and field stresses increase, the behavior of intact rock blocks plays an increasingly important role in understanding and estimating the overall rock mass strength. To model the brittle behavior of intact rock blocks, the stress–strain curve is usually idealized considering a linear strength mobilization approach (cohesion-weakening-friction-strengthening

Abstract not available

In this paper, the hydrogeological characteristics in the southern coalfields of China are first briefly outlined. Then, taking the Meitanba mine as an example, the evolution and modeling of mine water inflow are studied. Finally, the hazard characteristics related to mine water and mud inrush are analyzed. The results show that the main mine water sources in the Meitanba mine area are groundwater

The iron tailings of Bayan Obo mines are solid waste, which occupies land area and also causes environmental pollution; however, this waste can be recycled. In this study, based on the characteristics of iron minerals and fluorocarbonate contained in Bayan Obo iron tailings, clean magnetization roasting of iron minerals by bastnaesite from iron tailings during in-situ suspension magnetization roasting

A blasting experiment was conducted on iron ore samples by considering multiple coupling charge coefficients. The resulting internal fracture and damage characteristics were quantitatively analyzed via computerized tomography (CT), scanning, and three-dimensional (3D) model reconstruction. The results show that the iron ore primarily displayed radial and circumferential cracks along the blast hole

In order to make the slag from desulphurization and slag skimming (SDSS) to be comprehensively recycled and utilized, a combined process of beneficiation and building materials preparation was proposed to recover iron from SDSS, meanwhile to apply the remaining slag tailings as cement admixture. From this process, three iron-rich products were recovered in stages by clean gravity - magnetic separation

The Paleocene coals of the Salt Range in the Punjab Province of Pakistan have great economic potential; however, their trace element and stable isotopic characteristics have not been studied in detail except for a few sporadic samples. In this study, a total of 59 coal samples of which 14 are obtained from open cast mines have been investigated for elemental composition and δ13C-δ15N isotopic signatures

Chlorite, as the most representative gangue mineral associated with specularite, of which the separation of these two minerals is difficult. This paper investigated the depression effect of taurine on specularite/chlorite separation via flotation experiments, adsorption tests, contact angle measurements, Zeta potential detection, FT-IR measurements, and XPS analyses. The results of single mineral flotation

In deep underground engineering, rock burst and other dynamic disasters are prone to occur due to stress concentration and energy accumulation in surrounding rock. The control of dynamic disasters requires bolts and cables with high strength, high elongation, and high energy-absorbing capacity. Therefore, a constant resistance energy-absorbing (CREA) material is developed. In this study, the dynamic

In this work, the stable layer structure of serpentine, which seriously restricts the extraction of magnesium, was broken down, and a nearly 94% leaching efficiency of Mg was obtained by adding 5% fluorite powder. Compared with the system without fluorite, the Mg leaching efficiency increased by 36.42%. This result was achieved because the complexation of fluorinion (F−) with Si in serpentine promoted

Large amounts of solid wastes and flue gases are generated in iron and steel production process, probably leading to serious environmental pollution without duly handle. An innovative and green process of simultaneous reduction of zinc-bearing dusts and activation of low-rank coal was developed and its mechanism was clarified in this paper. Under the optimal conditions, the reduced zinc-bearing dusts

This work proposes a vibrating mesh screen as an alternative to the static mesh screen currently used in conventional flooded-bed dust scrubbers for removing airborne coal mine dust in the continuous mining environment. Fundamental assessments suggest that a vibrating screen may improve the dust collection efficiency of scrubber systems and mitigate the clogging issues associated with the conventional

To investigate the deformation mechanisms of rock under hydrostatic stress, destructive experiments were conducted on sandstone under different levels of hydrostatic stress and stress Lode angles. The results reveal that the shape of the strength envelope on the π plane gradually changes from the shape of the Lade criterion to the shape of the Drucker-Prage criterion with an increase in hydrostatic

The surrounding rock in tunnelling engineering and coal mining will sometimes be exposed to high temperature. Rock failure is the result of energy dissipation, and the study of the evolution and transformation behavior of energy is of great significance for the in-depth understanding of the deformation and failure of rock after high temperature. This study analyzed the intrinsic connection between

Coal fly ash is a typical secondary aluminum/silicon resource. The preparation of zeolite-type absorbent is a potential way for its value-added utilization, while the purity and adsorption property of zeolite are limited due to the occurrence of side reactions in the synthesis process. In this study, a designated composite consisted of crystalline zeolites and amorphous calcium silicate hydrate was

Horizon control, maintaining the alignment of the shearer’s exploitation gradient with the coal seam gradient, is a key technique in longwall mining automation. To identify the coal seam gradient, a geological model of the coal seam was constructed using in-seam seismic surveying technology. By synthesizing the control resolution of the range arm and the geometric characteristics of the coal seam,

Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on seepage. The ore body structure, pore distribution, pore and throat size, and pore network characteristics of topsoil, weathered, and semiweathered layers of ionic rare earth ore in southern Jiangxi Province were explored in this study. The effect of leaching operation on the

In this work, a novel process consisting of calcining-slaking followed by gravity separation for the enrichment of niobium (Nb) and titanium (Ti) from carbonatite pyrochlore ore was proposed, validated and compared with the current mainstream flotation method. During calcining of the pyrochlore ore, within which the carbonates were transformed into lime. Subsequently, when the calcined ore was slaked

This work aimed at revealing the mechanism of strong ground pressure behaviour (SGPB) induced by high-position hard roof (HHR). Based on the supporting structures model of HHR, a modified voussoir beam mechanical model for HHR was established by considering the gangue support coefficient, through which the modified expressions of limit breaking span and breaking energy of HHR were deduced. Combined

This investigation aims to explore the effects of stress conditions and rock cutting rates on hard rock fragmentation through indentation tests on a newly designed triaxial testing apparatus. This apparatus was designed to realize a triaxial loading and indentation test of cylindrical specimens using inserted tooth cutter. The boreability and crushing efficiency of granite rock was investigated by

Landslide displacement prediction can enhance the efficacy of landslide monitoring system, and the prediction of the periodic displacement is particularly challenging. In the previous studies, static regression models (e.g., support vector machine (SVM)) were mostly used for predicting the periodic displacement. These models may have bad performances, when the dynamic features of landslide triggers

Firedamp and coal dust explosion constitute a lion’s share in mine accidents in a global mining scenario. This paper reports a list of mine explosion disasters since last two decades, a critical review of the different prevention and constructive measures, and its recent development to avoid firedamp and coal dust explosion. Preventive legislation in core coal-producing countries, viz. China, USA,

In this study, the role of (NH4)2SO4 during the sulfurization of azurite and its response to flotation were investigated. The flotation results showed that adding (NH4)2SO4 prior to sulfurization decreased the formation of colloid in flotation pulp, and the floatability of the suppressed azurite caused by excess sodium sulfide was restored. After adding (NH4)2SO4 prior to sulfurization, the formation

Investigation on the mineral−water interactions is crucial for understanding the subsequent interfacial reactions. Currently, the hydration mechanisms of smithsonite are still obscure. In this paper, the adsorption of H2O at different coverage rates on smithsonite (1 0 1) surface was innovatively investigated using density-functional theory (DFT) calculations and molecular dynamics (MD) simulations

Isolated pillars in underground mines are subjected to uniaxial stress, and the load bearing cross-section of pillars is commonly rectangularly shaped. In addition, the uniaxial compression test (UCT) is widely used for determining the basic mechanical properties of rocks and revealing the mechanism of isolated pillar disasters under unidimensional stress. The shape effects of rock mechanical properties

Physical separation processes are best understood in terms of the behaviour of individual ore particles. Yet, while different empirical particle-based separation modelling approaches have been developed, their predictive performance has never been tested under variable process conditions. Here, we investigated the predictive performance of a state-of-the-art particle-based separation model under variable

Acoustic emission (AE) localization plays an important role in the prediction and control of potential hazardous sources in complex structures. However, existing location methods have less discussion on the presence of unknown empty areas. This paper proposes an AE source location method for structures containing unknown empty areas (SUEA). Firstly, this method identifies the shape, size, and location

Fully grouted bolts are a key component of the support system for underground openings. Although considerable effort has been made in the simulation of the reinforcement effect of the fully grouted bolts on the rock masses surrounding underground openings, most of the work has limited significance since the structural element approach is used. This study proposes a local homogenization approach (L-H

With the gradual depletion of shallow coal resources, the Yanzhou mine in China will enter the lower coal seam mining phase. However, as mining depth increases, lower coal seam mining in Yanzhou is threatened by water inrush in the Benxi Formation limestone and Ordovician limestone. The existing prediction models for the water burst at the bottom of the coal seam are less accurate than expected owing

To improve the efficiency of coal seam water injection, the influence of nanofluids on coal surface wettability was studied based on the nano drag reduction and injection enhancement technology in the field of tertiary oil recovery. The composition optimization and performance evaluation of nanofluids with nano-silica and sodium lauryl sulfate as the main components were carried out, and the effects

The characterization of micro-surface mechanical and electrical properties of the natural rock materials remains inadequate, and their macroscopic performance can be better comprehended by investigating the surface properties. With this purpose, the present research focuses on characterizing the micro-surface morphology, Derjaguin-Muller-Toporov (DMT) modulus, adhesion, and potential of granite, shale

Temperature affects the flotation of quartz in the calcium/sodium oleate (NaOL) system, while there is a lack of understanding of its potential mechanism. Therefore, in this work, the flotation response of quartz to temperature was investigated via micro-flotation experiments, interface property analyses, and theoretical calculations. Flotation results demonstrated that increasing temperature contributed

Rapid advances in deep-sea mining engineering have created an urgent need for the accurate evaluation of the undrained strength of marine soils, especially surface soils. Significant achievements have been made using full-flow penetration penetrometers to evaluate marine soil strength in the deep penetration; however, a method considering the effect of ambient water on the surface penetration needs

Flotation is a complex process that occurs in solid–liquid-gas multiphase systems, and its main factors include the minerals, separation medium, as well as various flotation reagents. The study of mineral properties and interactions with other components such as reagents and water lays the basic theoretical foundation for flotation. Density functional theory (DFT) calculations can qualitatively evaluate

Persistent froth is becoming more and more common in coal and mineral flotation plants and presents safety and operational challenges. No effective method has been developed to destabilise persistent froth. As a new initiative, this study examined the structural difference between persistent foam and coal froth, based on which a solution was developed to maximumly destabilise coal froth. Destabilisation