Exploring relationships of gross calorific value and valuable elements with conventional coal properties for North Korean coals

Coal in North Korean (NKC) is one of the most important products; however, based on various strategic policies its detail properties remain opaque even for general researchers. Since there are some signs for opening of the North Korea economy, this investigation as a modest effort is going to explore principle relationships among some essential parameters of NKCs such as gross calorific value (GCV), valuable elements and conventional properties by different statistical methods. Correlations indicated that ultimate parameters (carbon, nitrogen, and hydrogen) are the best GCV predictors for NKCs in comparison with proximate parameters (ash, moisture and volatile matter). Multivariable regression demonstrated that predicted GCV based on ultimate properties has a quite accuracy when correlation of determination was 0.99. Descriptive statistics processes showed that on average, the contents of valuable elements such as Ga and V for NKCs are higher than the world coal ranges and they can be considered as byproducts of combustion of NKCs. Pearson correlations indicated that Y may have a mixed organic-inorganic affinity while Ga and V mainly occur in the inorganic part (mineral matter) of NKCs. High inter-correlations between Ga-V and Al showed that aluminosilicates can be considered as their main bring minerals. (C) 2019 Published by Elsevier B.V.