Date of Graduation


Document Type


Degree Name

Bachelor of Science in Chemical Engineering

Degree Level



Chemical Engineering


Penney, Roy

Committee Member/Reader

Ackerson, Michael

Committee Member/Second Reader

Clausen, Ed

Committee Member/Third Reader

Ford, David

Committee Member/Fourth Reader

Hestekin, Jamie


Woo Pig Sulfate (WPS) has developed two methods for reducing levels of calcium sulfate in mine impacted waters, a “hot process” and a two-stage nanofiltration process. Both processes were designed to treat gypsum saturated water that is currently being pumped via interceptor wells to prevent the spread of a sulfate plume into a nearby community. Each solution was designed for Freeport McMoran’s Sierrita mine in Green Valley, Arizona, which was visited in order to gain insight about the problem. Below 250 ppm on the treated stream, nanofiltration and the hot process achieve overall recoveries of 84 and 99%, respectively. The waste, concentrated gypsum water, can be disposed of via evaporation ponds. Both processes are similar economically, but the hot process produces less waste, therefore requiring a smaller footprint for the evaporation pond, is less complex due to possessing fewer unit processes, and is less intensive maintenance-wise. However, since the hot process is more expensive than nanofiltration and is unused on an industrial scale, both processes are being presented as viable, with preference for either depending on whether the mine wants to maximize water recovery.


Hot Process, calcium sulfate removal, nanofiltration, mine water