81 - Mercury Mine Remediation Pilot Study of a New Amendment Technology

"Albemarle conducted a pilot study for mercury sequestration using MercLok™ at an abandoned mercury mine site in California. MercLok is a new remediation platform intended to sequester multiple species of mercury, preventing it from leaching or diffusing into groundwater and surface water.

Characterization of the study site found exposed calcines in three distinct areas, all with mercury content and leachability above regulatory thresholds for hazardous waste classification.

For the five-month pilot study in 2021, layers of unamended (controls) and MercLok-amended calcines were arranged in 16, 13-gallon, open-top bucket “reactors” representing two alternative applications and various dosages. Rainwater entered the reactors to allow natural leaching of mercury. Leachate was sampled monthly and analyzed for total, dissolved, and methyl mercury, plus other metals, minerals and field measurements. The calcine solids were also analyzed at the beginning and end of the exposure/leaching period for total and leachable mercury and other metals.

Results indicate MercLok reduced up to 99% of leachable mercury and 75% of methyl mercury. This sequestration efficacy was reproduced in rainwater leachate and in acid-based leaching tests. MercLok reduced the leachability of mercury to below hazardous solid waste classification limits and leachate concentrations below water quality criteria. MercLok could offer environmentally protective options for remediation of calcines at legacy mercury mines."

Authors: Daniel Griffin, Stephen McCord, Greg Reller ,Jon Miller, Se Hye Kim