Influence of Copper Recovery on the Water Quality of the Acidic Berkeley Pit Lake, Montana, U.S.A.

Abstract

The Berkeley Pit lake in Butte, Montana, formed by flooding of an open-pit copper mine, is one of the world's largest accumulations of acidic, metal-rich water. Between 2003 and 2012, approximately 2 × 10(11) L of pit water, representing 1.3 lake volumes, were pumped from the bottom of the lake to a copper recovery plant, where dissolved Cu(2+) was precipitated on scrap iron, releasing Fe(2+) back to solution and thence back to the pit. Artificial mixing caused by this continuous pumping changed the lake from a meromictic to holomictic state, induced oxidation of dissolved Fe(2+), and caused subsequent precipitation of more than 2 × 10(8) kg of secondary ferric compounds, mainly schwertmannite and jarosite, which settled to the bottom of the lake. A large mass of As, P, and sulfate was also lost from solution. These unforeseen changes in chemistry resulted in a roughly 25-30% reduction in the lake's calculated and measured total acidity, which represents a significant potential savings in the cost of lime treatment, which is not expected to commence until 2023. Future monitoring is needed to verify that schwertmannite and jarosite in the pit sediment do not convert to goethite, a process which would release stored acidity back to the water column.

Post Gold King Mine Spill Investigation of Metal Stability in Water and Sediments of the Animas River Watershed

“…33, 48, 49 Enhancing oxidation of Fe(II) minerals in AMD has been shown to be effective in removing heavy metals from solution by sequestration in jarosite. 50, 51 The stability of jarosite can be affected by pH, 52, 53 metal substitution 54 and association with other minerals. 55 Furthermore, the geochemical weathering increases the bioavailability of the metal-bearing minerals; thus, metal-bearing jarosite poses a higher risk for exposure than unweathered minerals.…”

Assessment of water quality from the Blue Lagoon of El Cobre mine in Santiago de Cuba: a preliminary study for water reuse

“…However the copper content in the El Cobre Blue Lagoon is far less than can be find in the Berkeley Pit lake in Montana with ca. 0.15g.L -1 copper enabling copper mining directly from the lake waters (Tucci and Gammons 2015). A wide variety of remediation methods for such moderately acidic waters have been investigated, such as sulfate reduction (Frömmichen et al 2003), limestone neutralization, (Watten et al 2005), phosphorus amendment (McCullough 2007, Neil et al 2009 and in-situ biologically based treatment such as wetlands or anoxic limestone drains (Kalin 2004), bioreactors stimulating sulfate-reducing bacteria (Bozau et al 2007) and reactive barriers for groundwater (Amos and Younger 2003).…”

“…The site is a major tourist attraction (Cuban Tourism, 2016), and people bathe in its waters, believed to possess medicinal properties. However, until today no rehabilitation of this area has been done contrariwise to other pit lakes from former copper mine sites such as Berkeley Pit Lake, Montana, USA (Tucci and Gammons 2015).…”

The Importance of Catchments to Mine-pit Lakes: Implications for Closure

“…Closure and management plans for acidic pit lakes often focus on how to improve water quality by increasing pH. 'Active' chemical treatments, such as liming (Geller and Schultze 2013b), remining (Tucci and Gammons 2015), installation of in-lake bioreactors (Preuss et al 2007), and whole-lake bioreactors (Geller and Schultze 2013a;McCullough et al 2008) are potential strategies. Aside from liming and remining, in-lake and whole-lake bioreactors are still unproven approaches to in situ remediation of pit lakes (Geller and Schultze 2013b), and relying on sulfate reduction is unlikely to be effective in weakly acidic low-sulfate lakes (Lund and McCullough 2008).…”