Geothermal in Mine Closure: Visualizing the Hydromechanical Properties of a Geothermally Facilitated Bioreactor

Abstract

The world of today has the more abandoned mines than ever before. Many of these are located in remote regions, set apart from energy sources, people and infrastructure, rendering the necessary remediation efforts in these areas slow-moving and even nonexistent. The primary demand from the industry for these sites is a passive system that utilizes locally available and cheap material. Often the geothermal gradient available in mines, or the corresponding geothermal reservoir conditions proximal to the mine, is a viable heat energy source that can provide advantageous temperature conditions for established remediation techniques, namely bioremediation, which can run on diverse, inexpensive, and locally available material. Although geothermal direct use and bioremediation are proven technologies when practiced independently, the combination of both is not straight forward. The following paper will address the hydromechanical intricacies of this process and its promise for providing relevant remediation to abandoned metal mines in remote regions. This study involves the use of COMSOL in simulating the thermally driven convective cells produced in a porous bioreactor apparatus. The simulation’s results illustrate the potential benefits of such a system based on the hydraulic residence time and thermally augmented reactivity of chemical species flowing through the reactor. The input parameters are based on the environmentally relevant data gathered through field surveys of Rico, Colorado, an old mining town in the Rocky Mountains of southwest Colorado.