Coal discard dump rehabilitation using kenaf: Proof of concept study

¹ Faculty of Natural and Agricultural Sciences, North-West University, South Africa
² Faculty of Engineering, North-West University, South Africa

^* Corresponding author: marco.leroux@nwu.ac.za

Abstract

Coal discards are a side effect from coal mining and beneficiation. There are currently billions of tons of discards, with South Africa reporting over 1000 Mt, mainly fine and ultra fine coals. This number increases annually by 60Mt, creating a twofold situation of a) potential lost product and b) cost intensive future rehabilitation. This paper focusses on the latter, presenting an alternative way to rehabilitate current discard dumps aiming to create a new market whilst enhancing job security. During this study, coal discards from two sites near Witbank, South Africa, were sampled and analysed for quality. It was found that there was no difference in plant growth and physiology between the plants grown in the three different samples (pure soil or discard coal and a 50/50 mixture). Germination time was measured to be between three and four days for all the repetitions and samples. Kenaf showed the propensity for moderate metal absorption including heavy metals and rare earth elements (REEs). These metals concentrated in different parts of the plant with REEs being mostly absorbed in the roots of the plants while other metals will diffuse into the stems and leaves of the Kenaf. It opens possibilities for additional metal recovery.