Dewatering studies of fine clean coal. Technical report, March 1, 1992--May 31, 1992

Abstract

Physical cleaning of ultra-fine coal using an advanced froth flotation technique provides a low ash product, however, due to high surface area of particles the amount of water associated with clean coal is high. Economic removal of water to 20 percent or lower moisture level from the clean coal froth will be important for commercial applicability of advanced froth flotation processes. The main objective of the present research program is to study and understand the dewatering characteristics of ultra-fine clean coal and to develop process parameters to effectively reduce the moisture to less than 20 percent in the clean coal product. The research approach under investigation utilizes synergistic effect of metal ions and surfactant to lower the moisture of clean coal using a conventional vacuum dewatering technique. The studies have identified a combination of metal ions and surfactant found to be effective in providing a 22 percent moisture filter cake. During the third quarter, efforts were made to understand reagent adsorption mechanism. Adsorption studies indicated that the presence of metal ions enhanced adsorption of surfactant. It appears that metal ions induced floc formation at pH {approximately}7.0, which are hydrophilic in nature, however addition of surfactant restores the hydrophobicity. Organic polymers along with metal ions were found to be effective in dewatering of fine coal. Continuous filtration tests conducted using a drum filter provided a filter cake containing 24 percent moisture. Additional studies on mechanism of adsorption and continuous filtration using AC Electro-Coagulation will be conducted in the next quarter.