Neutralization of Acidic Discharges from Abandoned Underground Coal Mines byAlkaline Injection

摘要

The hydrologic characteristics of two abandoned underground coal mine sites, nearLatrobe, PA, and Unionntown, PA, were investigated by the U.S. Bureau of Mines for possible implementation of alkaline injection into the mine pools as a means of abating their acid discharges. A quantity of alkaline reagent (sodium hydroxide) sufficient for a one-time neutralization of the water in this portion of the pool was added. Although nearly all of the neutralizing reagent has moved away from the injection wells within 6 weeks, no evidence of neutralization was noted at the mine discharge during the study period. The lack of neutralization probably occurred because the injection wells did not intercept a primary flow path through the mine. Criteria for successful application of alkaline injection at this or other sites include (1) positive identification of the primary flow paths through the mine pool and (2) addition of quantities of alkaline reagent sufficient to neutralize the entire volume of the pool along the primary flow path.