Co-treatment of steel slag and oil shale waste in cemented paste backfill: Evaluation of fresh properties, microstructure, and heavy metals immobilization

The environmentally sustainable treatment of steel slag (SS) and oil shale waste (OSW) is a significant concern in the field of industrial development. The mining industry also faces challenges related to the high costs and carbon emissions associated with ordinary Portland cement (OPC), leading to environmental pollution. To address these challenges, this study aimed to develop a cost-effective and environmentally friendly binder for cemented paste backfill (CPB) by utilizing SS and calcined oil shale waste (COSW) as primary precursors. Extensive investigations were conducted to evaluate the properties of the CPB sample with varying COSW content, including rheological properties, mechanical strength, and microstructure. The binder sample was comprehensively characterized using isothermal calorimetric analysis, X-ray diffraction (XRD), thermogravimetry (TG), and scanning electron microscopy (SEM). Based on systematic experimentation, an optimal blend ratio for the binder was determined, consisting of 60 wt% SS, 15 wt% COSW, 15 wt% phosphogypsum (PG), and 10 wt% OPC. The exceptional performance of the binder was attributed to the substantial formation of precipitated ettringite (AFt), resulting in a more compact structure and improved mechanical strength. Additionally, a sequential extraction test revealed that the heavy metals in the CPB sample were mainly present in the residual fraction, demonstrating the effective immobilization of heavy metals by the binder.

Exploring the role of economic and institutional indicators for carbon and GHG emissions: policy-based analysis for OECD countries

Most of the developed countries across the globe have targeted to attain sustainable economic growth. With this focus, the current study evaluated 29 OECD countries over the time period of 1990 to 2018 to analyze the influence of economic and environmental indicators, i.e., export diversification, institutional quality, macrocosmic variables on carbon dioxide, and greenhouse gas emissions. The current study used the quantile regression and generalized method of moments approach on the selected panel. Our comprehensive econometric approach allows us to reveal that export diversification negatively affects carbon emissions but promotes greenhouse gas emissions. Similarly, institutional quality, economic growth, financial development, and economic growth helps to reduce carbon emissions but increase greenhouse emissions. In comparison, trade openness exhibits a positive influence on carbon emissions but a negative on greenhouse gas emissions. Besides, urbanization is found one of the major reasons for environmental degradation. In light of empirical fact findings, this study commends some innovative policy insights for scholars, governors, and policymakers.

Does geothermal energy and natural resources affect environmental sustainability? Evidence in the lens of sustainable development

Climate change and global warming have been driven by a rise in carbon dioxide (CO₂) concentrations in recent decades, posing a danger to environmental sustainability. Thus, this research scrutinizes the effects of two types of energy (coal and geothermal) and natural resources on CO₂ emissions in 10 newly industrialized countries (NICs). The study also considers the role of financial globalization using a data between 1990 and 2019. This research applied a fresh nonparametric econometric technique termed "method of moments quantile regression (MMQR)." This approach is resistant to outliers and produces an asymmetric connection between variables. Furthermore, the long-run estimators (AMG and CCEMG) are employed as a robustness check. The findings reveal that natural resources, coal, and economic growth contribute to the degradation of the environment in the NICs in all quantiles (0.1-0.90). However, geothermal energy aids in enhancing environmental sustainability at all quantile distributions (0.1-0.90). Our findings are robust with alternative methods (AMG and CCEMG). The research's outcomes have the potential to help NICs nations design policies. Finally, based on the research results, a policy framework is proposed to solve the objectives of SDGs 7 and 13.