1. College of Mathematics and Big Data, Anhui University of Science and Technology, Huainan 232002, China
2. Hefei GStar Intelligent Control Technical Co. Ltd., Hefei 230088, China
3. Anhui Provincial Key Laboratory of Process Industry Online Detection and Intelligent Systems, Hefei 230088, China
Abstract:To address the high-precision demand for online coal quality detection in coal-fired copper smelters, this study proposes a genetic algorithm (GA)-optimized extreme gradient boosting decision tree (XGBoost) ensemble model (GA-XGBoost), enhancing the industrial applicability of laser-induced breakdown spectroscopy (LIBS) for complex coal analysis. To overcome overfitting and limited generalization in traditional XGBoost caused by hyperparameter sensitivity, GA-XGBoost implements a GA-based global search strategy to adaptively optimize key hyperparameters (e. g., learning rate, tree depth, regularization parameters) coupled with binary-encoded chromosome representation for dynamic spectral feature selection, effectively suppressing noise in 14 328-dimensional LIBS data. Validation employed 59 standard coal samples from Datong, Shanxi (bituminous coal) and Ordos, Inner Mongolia (lignite). Preprocessing via adaptive iteratively reweighted penalized least squares (airPLS) and Savitzky-Golay filtering reduced spectral dimensions to 500, with dominant features identified by SHapley Additive exPlanations (SHAP) values. Comparative experiments demonstrated GA-XGBoost's superiority over XGBoost, random forest (RF), support vector machine (SVM), multiple linear regression (MLR), and partial least squares (PLS) in predicting ash content and calorific value. For ash content, GA-XGBoost achieved a 0.053 increase in R2, 0.964% reduction in RMSE, 0.324% decrease in MAE, and 1.494-percentage-point lower RSD. For calorific value, it yielded a 0.003 R2 improvement, 0.021 MJ·kg-1 RMSE reduction, 0.07 MJ·kg-1 MAE decrease, and 0.871-percentage-point RSD reduction. External validation using 20 unmodeled on-site coal datasets confirmed robustness in industrial environments, with errors constrained within 1% (ash) and 0.5 MJ·kg-1 (calorific value). The GA-LIBS integration addresses spectral interference and generalization challenges, establishing a unified framework for real-time multi-parameter coal analysis. Field deployment in an operational copper smelter demonstrated seamless integration into LIBS online systems, providing a technically viable pathway toward clean and efficient coal utilization.
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