Amine-functionalized solid adsorbents exhibit broad prospects in CO₂ capture from flue gases due to their high adsorption capacity and selectivity. However, reported adsorbents are still facing challenges, including high costs, the easy agglomeration of polyamines, and limited adsorption temperature ranges. In this study, sepiolite-based mixed amine adsorbents are prepared by synergistically impregnating acid-treated sepiolite with a mixture of polyethyleneimine (PEI) and diethanolamine (DEA). Results show that at a PEI/DEA loading ratio of 1:1 and a mixture loading of 60wt%, the CO₂ adsorption capacity of the resulting adsorbent increases from 0.58 mmol/g for acid-treated sepiolite to 2.89 mmol/g at 60 °C, and remains above 2.50 mmol/g after 10 cycles. Meanwhile, the optimized adsorbent maintains a capacity of over 2.44 mmol/g within the temperature range of 30–70 °C. Additionally, the CO₂ selectivity and maximum heat of adsorption for the optimized adsorbent are calculated to be 1184 and 60.08 kJ/mol, respectively. An improved CO₂ adsorption capacity is obtained, an increase from 0.052 mmol/g for acid-treated sepiolite to 1.60 mmol/g. Furthermore, an in-situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) analysis reveals that the introduction of DEA into PEI helps in polyamine dispersion, thereby enhancing CO₂ adsorption capacity. The CO₂ capture mechanism follows a zwitterionic reaction, where CO₂ is ultimately converted into carbamate and carbamic acid. Overall, the as-prepared sepiolite-based mixed amine adsorbents, which are characterized by high CO₂ adsorption capacity and selectivity, low cost, broad adsorption temperature range, moderate heat of adsorption, and good cycle stability, show promising potential for industrial applications.

Heavy metals (HMs) in acid mine drainage (AMD) pose serious threats to aquatic life and soil. Biosorbents are promising materials to remove HMs from wastewater. Herein, food waste compost was used as a low-cost and sustainable biosorbent to remove Fe³⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ from an AMD and other model solutions with an initial pH of ∼2.24. Batch adsorption tests were conducted to systematically investigate the influences of initial pH, compost dose, the presence of Fe³⁺ and SO₄²⁻ ions, and the pH-induced Fe precipitates on the removal performance. The involved removal mechanisms were explored by conducting stepwise precipitation tests, sequential extraction tests, and Fourier transform infrared spectroscopy (FTIR) characterization. It was found that the addition of the compost removed over 90% of Zn, Ni, Cu, and Pb at pH 5.80, 5.50, 4.50, and 3.00, respectively. At low compost doses, the presence of Fe³⁺ and SO₄²⁻ ions hindered the removal since the competition effect of Fe³⁺ ion and lower absorbability of metal-sulfate complexes, respectively. Sequential extraction tests revealed that higher fractions of Fe, Cu, and Pb were strongly immobilized through complexation and precipitation relative to Ni and Zn. Additionally, the pH-induced Fe precipitates did not favor the removal of the HMs, probably due to the adsorption of organic components released from the compost. This study suggests that compost has the potential to remove HMs from acidic wastewater without pre-neutralization.

Driven by the “dual carbon” and “green metallurgy” targets, the steel industry feels the pressure of carbon emission reduction and steel slag resource utilization. Since the year 2000, accelerated carbonation technology using basic oxides in steel slag to store CO₂ has been widely investigated worldwide. In this study, the chemical and mineral compositions and the main physical properties of different steel slags are summarized to achieve the dual purpose of CO₂ mineralization and steel slag increment. This paper also summarizes the latest advancements in the direct carbonation of steel slag. Following the carbonation process, residual free calcium oxide and magnesium oxide can be further carbonated to aid in the preparation of building materials. The direct carbonation method improves the use of steel slag as an aggregate and in cementitious applications, exhibiting effective performance in steel-slag-based composites. Given the limited extent of steel slag carbonation and the modest utilization of available products, this paper explores the current research on carbonated steel slag for building material fabrication and discusses the variety of green building materials.

Red mud (RM) is a highly alkaline solid waste generated during alumina production. With the rapid development of the alumina industry, RM production has increased dramatically, reaching a rate of 120–150 million tons annually. This substantial production leads to several issues, including the occupation of extensive land areas and the necessity for costly maintenance. Furthermore, it may cause pollution and harm to the surrounding ecological environment. Therefore, RM needs to be treated and recycled in an environmentally friendly way. Utilizing RM as an environmental remediation material effectively leverages RM resources. Red mud environmental remediation materials (RM-ERMs) are usually prepared by activating RM and synergistically using RM with other components. RM-ERMs are generally applied in three areas of environmental pollution control: wastewater purification, exhaust gas purification, and soil remediation. The use of RM-ERMs has been proven to be a promising strategy that not only removes various types of waste from the environment but also enables the effective use of bulk solid waste RM, achieving the purpose of treating waste with waste. Furthermore, exploring the current limitations of RM as an environmental remediation material provides valuable insights and suggestions for future research endeavors in this area.

The production of coal-based solid waste (CBSW) from coal mining operations poses a significant threat to the ecological environment in mining regions. This research addresses the proper management of CBSW accumulation by utilizing coal gangue, fly ash, and gasification slag as primary materials for backfill preparation. This study focused on evaluating the early uniaxial compressive strength and fluidity of the backfill while investigating the changing characteristics of early compressive strength, fluidity, and microstructure during the early age of backfill development. Findings showed that the slurry fluidity significantly decreased as the mass concentration increased, whereas factors such as the aggregate–cement mass ratio, fine aggregate content, and fiber content demonstrated no noticeable impact on slurry fluidity. Notably, the early compressive strength of the backfill decreased significantly with an increase in the aggregate–cement mass ratio; however, increases in the mass concentration and fine aggregate content effectively enhanced the early compressive strength of the backfill, serving as key influencing factors. The inclusion of fiber significantly enhanced the early compressive strength of the backfill, with the optimal fiber concentration determined to be ∼0.2wt%. Furthermore, increasing the mass concentration or fine aggregate content alleviated the negative impacts of higher aggregate–cement mass ratios on early compressive strength. However, it must be noted that an elevated fine aggregate content may reduce the reinforcing effects of mass concentration on early compressive strength. This leads to enlarged void structures in the samples, whereas increasing the fine aggregate content reduces the void size and range, thereby improving the early compressive strength of the backfill.

This paper examines the performance of three families of percussive drilling methods, Churn (CD), Down-the-Hole (DTH), and Top-Hammer (TH), through the prism of time scales. These time scales characterize different aspects of the dynamics of the drilling process. One time scale represents the travel time of an elastic perturbation in the hammer, while another one corresponds to the travel time in the drillstring and/or the bit assembly. The duration of the response of the bit/rock interface to an impulse load, and the duration of the pulse generated by the impact of the hammer in DTH and TH tools are two other time scales. Within the simplified modeling framework considered in this study, the dynamics of the percussion tools is at most controlled by three numbers, which are ratios of time scales. However, some of these numbers could be irrelevant depending on the design and class of the percussion drilling system, because they are either too small or too large and thus do not affect the dynamical response. For example, the energy transfer efficiency-the fraction of the impact energy effectively delivered to the rock-depends on one number when drilling with a TH tool, but on three numbers for a hydraulically powered DTH tool. This approach enables the identification of the point of maximum efficiency in the parametric space of the time scale ratios. The so-called sweet spot can thus be understood as representing an optimum match of the different timescales characterizing the drilling system. For instance, maximum performance is achieved with a TH tool if the two time scales controlling its dynamics are equal.

In the face of the energy revolution and industrial change in the new era, intelligent coal mining is the only way to achieve high-quality development of the coal industry. Intelligent coal mining has endowed the coal mine geological guarantee system with new connotations and promoted the higher-level development of coal mine geological guarantee technology. The significance of the geological guarantee system in the entire process of coal mining is systematically analyzed. The research and application status of surface, borehole, and “four-while” detection technology is reviewed in detail. The key technologies and development progress of intelligent geological assurance are introduced, and the future development direction of intelligent geological guarantee systems in China is comprehensively considered. High-precision detection results are the basis of geological guarantee. Based on conventional three-dimensional (3D) seismic exploration technology, 3D seismic high-precision imaging methods, intelligent identification methods of geological structures, intelligent inversion of stratum parameters, joint interpretation of reflected and diffracted waves for small-scale geological anomalies, and key technologies of underground exploration, which provide high-precision detection results for geological guarantee, are investigated. In terms of the construction of dynamic geological models, the dynamic detection technology of coal–rock interface with mining based on air-coupled radar has been proposed, and the significance of an online monitoring system is discussed. Based on the large amount of exploration data, the real-time data processing and visualization software and dynamic update method of the 3D geological model are established. This study systematically classified the key technologies of coal mine geological guarantee, specified the future direction of intelligent geological guarantee, and provided a reference for the development of intelligent mining geological assurance systems in coal mines.

Phase change materials offer high energy-storage density and maintain a constant temperature during energy storage; however, they face many challenges, such as leakage issues and low thermal conductivity in practical applications. Minerals have excellent thermal and chemical stability, high mechanical strength, good thermal conductivity, and natural porous structures and are increasingly used in composite phase change materials (CPCMs). This review summarizes methods for the preparation and optimization of mineral-based CPCMs. Additionally, we highlight their promising practical applications, including high-temperature energy storage, building energy efficiency, and waste heat recovery, while also discussing future development prospects.

Constant attempts have been made throughout human history to find solutions to complex issues. These attempts resulted in industrial revolutions and the transition from manual labor to machines and new technologies. The latest advancements in artificial intelligence (AI) are revolutionary. The use of these smart technologies in mining can lead to increased profitability, enhanced performance, improved safety, and better adherence to environmental regulations. In this paper, the applications of AI and digital twin systems in mining operations are reviewed, covering various components, including mineral exploration, drilling, blasting, loading, hauling, mineral processing, and environmental issues. Critical data inputs for each component are identified, and relevant tools and methods are discussed. These will facilitate the development of digital twin models with learning, simulation, prediction, and optimization capabilities. This study provides valuable insights into fully integrated digital twin mining systems, which will significantly improve mining efficiency and sustainability. Although innovative technologies, such as the Internet of Things (IoT) and other intelligent tools, are increasingly being used in the mining sector, many mining processes still depend on human oversight to deal with challenges, such as remote operations, geological variability, high investment costs, and a skills gap. There is, therefore, significant potential to enhance the use of sensors and IoT devices to support data collection for more integrated and powerful digital twin systems to drive further innovation and operational improvements across the mining value chain.