Reclamation is regarded as one of the mining processes that can lessen the environmental impact of its production, particularly for large-scale coal mines that emit significant quantities of ...greenhouse gases. However, the assessment and evaluation of the reclamation process primarily rely on qualitative methods. Utilizing LANSAT8 Operational Land Imager (OLI) remote sensing in conjunction with GIS, this study aimed to develop a quantitative method for validating the efficacy of a reclamation procedure applicable to the emerging trend of carbon reduction. The empirical formula utilized to compute the annual carbon sequestrations of the reclamation area in the Mae Moh mine exhibited the appropriate spatial relative standard deviation (S-RSD) at 98.25%. The findings indicate that the reclamation area reached its highest level of carbon sequestration in 2022, at 331.28 ± 11.89 ktCO2e, surpassing the baseline of 126.53 ktCO2e. Furthermore, the approach demonstrates significant potential in improving the standard method for assessing reclamation through reforestation.
As one of the solutions to tackle climate change caused by excess carbon dioxide (CO2) emission, CO2 geological storage has been increasingly implemented globally to store CO2 securely and ...permanently in the subsurface. In the current study, structural trapping, which shows the potential of initial CO2 containment and integrity of the subsurface structure, is experimentally investigated with CO2 leakage assessed. CO2 containment is quantified by CO2 column height, which describes the amount of CO2 accumulated in the formation underneath seal rock and is controlled by a balance between capillary and gravitational forces acting on formation brine and invading CO2. While previous studies considered only contributions from seal rock (i.e., “nonrelative”), the current study examines a concurrent contribution from reservoir rock as a seal–reservoir “relative” column height since CO2 storage as an analogy to petroleum reservoir is a structural trap consisting of the reservoir and impermeable seal covered. A distinctive discrepancy was found between the resultant relative and nonrelative column heights. The nonrelative column heights were positive (∼3000 m), implying a high potential for CO2 storage. On the contrary, with reservoir rock contribution considered, the relative column heights were negative (∼−1800 m), suggesting CO2 leakage through the structural trap. This was attributed to a relatively larger reservoir pore size (5.72 nm) than that of seal rock (4.04 nm). Hence, the contribution from reservoir rock characteristics is non-negligible when analyzing CO2 storage potential. Owing to CO2 dissolution in formation brine, CO2-induced effects including a geochemical reaction between acidic carbonated brine and rocks were also investigated. Rock dissolutions in both seal (claystone) and reservoir (limestone) rocks were observed with changes in the pore size, leading to lower storage potential. Further attempts to improve the column height were made by hydrophobizing seal rock via surfactant adsorption, although the changes were slight and could only facilitate a possible leakage (less negative height column).
In this scientific report, a new technique of artificial intelligence which is based on k-nearest neighbors (KNN) and particle swarm optimization (PSO), named as PSO-KNN, was developed and proposed ...for estimating blast-induced ground vibration (PPV). In the proposed PSO-KNN, the hyper-parameters of the KNN were searched and optimized by the PSO. Accordingly, three forms of kernel function of the KNN were used, Quartic (Q), Tri weight (T), and Cosine (C), which result in three models and abbreviated as PSO-KNN-Q, PSO-KNN-T, and PSO-KNN-C models. The valid of the proposed models was surveyed through comparing with those of benchmarks, random forest (RF), support vector regression (SVR), and an empirical technique. A total of 152 blasting events were recorded and analyzed for this aim. Herein, maximum explosive per blast delay (W) and the distance of PPV measurement (R), were used as the two input parameters for predicting PPV. RMSE, R
, and MAE were utilized as performance indicators for evaluating the models' accuracy. The outcomes instruct that the PSO algorithm significantly improved the efficiency of the PSO-KNN-Q, PSO-KNN-T, and PSO-KNN-C models. Compared to the three benchmarks models (i.e., RF, SVR, and empirical), the PSO-KNN-T model (RMSE = 0.797, R
= 0.977, and MAE = 0.385) performed better; therefore, it can be introduced as a powerful tool, which can be used in practical blasting for reducing unwanted elements induced by PPV in surface mines.
Ground vibration from blasting is generally controlled by reducing the explosive charge weight per delay. However, lowering explosive charge weight per delay may increase the fragmentation size of ...blasted material. Richards (2008) introduced a wavefront reinforcement model to account for input burden, spacing and sequential delay timing for each blasthole. This study tested his wavefront reinforcement model with a predetermined surface wave velocity at 350 m/s to determine the direction and extent of increases in ground transmitted vibrations. The results from 21 experimental blasts on overburden material (Red Beds) at various patterns and delay timing at Mae Moh Mine indicated that ground vibrations were higher in areas of wavefront reinforcement compared to non-wavefront reinforcement in 16 (76%) of the experimental blasts. The designed drilling patterns and sequential initiation has shown that the wavefront reinforcement areas mainly occur in front and to the back of the blasting direction.
The regulated maximum peak particle velocity (PPV) from blasting operations of an open-pit coal mine is less than 2 mm/s to prevent mainly any public disturbance such as ground vibration and air ...blast. However, the blast-induce ground vibration can also decrease the stability of pit slope, which has not been intensively studied. A claystone pit wall, which is geotechnically investigated as having a plane failure type and the natural condition factor of safety (FS), has been selected for this study. The FS is selected to measure the effect of blast-induced ground vibration on the slope stability. The limit equilibrium, pseudo-static 1 (), and pseudo-static 2 () methods are used to determine the FS. The vibration results of blasting monitored at three slope positions: crest, middle, and toe, from two areas at the same pit wall, are recorded by blasting seismographs. Maximum charge weight per delay and the distance from blast areas to seismographs are collected to construct the scaled distance. The percentage change of FS of three methods from both areas compared to natural condition FS are all less than 4 percent considered that the slope stability is safe from blasting vibration (less than 15 percent). The relationship between the FS and maximum PPV from the limit equilibrium, pseudo-static 1 (), and pseudo-static 2 () methods indicate that the adverse maximum PPVs given the unity FS are 16.60 and 4.58, and 4.74 mm/s, respectively. The regulated PPV less than 2 mm/s at the mine is reasonable to prevent any possible plane failure. However, many impact parameters have not been included in this study, and their effects may disturb the pit wall stability.
The Mae Moh basin is located in the Mae Moh District of Lampang Province, which is about 26 km east of Lampang City. The basin floor is about 320-340 m above mean sea level. The Mae Moh basin ...consists of three formations, namely the Huai King, Na Khaem, and Huai Luang formations, in ascending order. Their total thickness is nearly 1,000 m. The Na Khaem formation is a coal measure comprising three main coal zones, Q, K, and J. This study introduces preliminary approaches to determining minimum thickness suitable for extracting thin coal seams meeting coal quality requirements or maximum allowable thickness of diluting partings requirements. The approach considers heating value as the main parameter to be determined and considered in different scenarios of losses and dilution. The study findings indicate that high-quality coal-bearing diluting rock partings, such as BK and BK3, can be excavated with K3 coal seam, and the allowable diluting parting thickness ranges 1.68-5.3 m at the required heating value of 2,800 kcal/kg. These diluting parting thicknesses can constitute up to 20-50 % of excavation thickness of K3 coal seam. Low-quality coal-bearing diluting rock partings, such as TK1, TQ, and BQ4, cannot be excavated with K and Q coal seams at all. Coal-bearing partings should have heating value more than 1,000 kcal/kg for having potential to be excavated with coal seams.
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