Evaluation of fly-ash based artificial zeolite formation as treatment for salt-laden process water from eastern Montana coal operations.

摘要

Montana has roughly 120 billion tons of coal reserves, more than any other state in the U.S. However, Montana ranks low among coal-producing states. Various factors including coal quality, mining conditions, resulting economics, transportation costs, taxation and environmental regulation contribute to Montana's lag. A major factor that has historically limited the market for certain Montana coal reserves is high-sodium content and resulting degradation of combustion systems. The issue is compounded by the increased focus on control of minor pollutants, including sodium, in industrial effluents and the already limited capacity of major coal reserve areas such as the Powder River Basin (PRB) to absorb increased salt presence. This thesis presents the work related to coal development for eastern Montana, specifically focusing on wastewater issues associated with the processing and removal of sodium from coal matrices. A variety of means exist to remove sodium from process waters, but most options are economically disadvantaged and still produce waste streams for subsequent disposal. This work focuses on a technology that, if applicable, has the propensity to combine waste streams and produce a by-product that is not only beneficial but saleable. Artificial zeolite formation was evaluated as the primary means to treat effluent, hoping to capitalise on the characteristic aluminosilicate structure of fly-ash by product and the ability of sodium, to not only act as a structure formation director, but be included in those structures effectively combining waste streams, cleaning process water, and producing a by-product that is a benefit to operations. Results indicated that process variables are still widely not understood, but formation of a zeolite phase (or conversely a geopolymer) favours conditions of high pH, moderate sodium solution concentration, low solid to liquid ratios, and low temperatures.;Keywords: extraction, fly-ash, geopolymer, Montana, wastewater, zeolite