β Scribed by Jaewon Choung; Zhenghe Xu; Jozef Szymanski
No coin nor oath required. For personal study only.
A detailed study on an integrated process featuring three distinct mechanisms (i.e., hydrophobic extraction, coagulation and flocculation) is presented. In this process, fine coals in the tailings stream are extracted into a mineral oil by hydrophobic extraction, while coagulant and flocculant are used to aid effluent clarification by coagulation/flocculation. With a single stage process, a coalβinβoil mixture is produced as a potential fuel, while clarifying the water for recycling. The hydrophobicity of coal is found to be a key parameter in coal extraction. The addition of mineral oil prior to flocculant and coagulant, especially in the presence of fine clays, is beneficial for recovering weakly hydrophobic fine coals. Fine clays are found to stabilize coalβrich oil droplets, reducing coal recovery. The presence of hydrophobic coal enhances droplet coalescence and improves process performance. In a case study using a tailings stream from OBED coal preparation plant, it was found that reβgrinding of original tailings is necessary to expose fresh hydrophobic surfaces. Applying this single stage unit operation to a tailings containing 52% ash, a combustible recovery greater than 85% in the form of coalβinβoil mixture at product ash content less than 14 wt% was achieved.
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This paper reports a case study of a well-advanced deployment of a strategic program of business process performance improvement at a major Middle Eastern utility company. It illustrates the strategies, organizations, methodologies, and stages that the company has followed in implementing its improv