Case Studies Chapter 7

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1. The Argo Tunnel - Pulsed Limestone Bed Treatment
2. Bisbee No. 7 stockpile – BioSulphide process

1. The Argo Tunnel - Pulsed Limestone Bed Treatment

(Demonstration)

Background

The Argo Tunnel is located in Idaho Springs, Clear Creek County, Colorado, approximately 30 miles west of Denver. The tunnel was constructed to provide drainage and transportation for several connected gold mines. The tunnel continues to drain acidic mine water at an average rate of 280 gallons per minute. The environmental media affected are surface water and, to a much lesser extent, groundwater.

Treatment Applied

A conventional lime water treatment plant was constructed in 1998 and has been operating continuously. Primary contaminants include acidity and a host of heavy metals, including aluminum, copper, iron, manganese and zinc.

A pilot treatment system was operated and studied periodically from 2004 through 2007 by the United States Geological Survey (USGS) Leetown Science Center utilizing a pulsed limestone bed treatment system at 230 L/min.

Pulsedlimestonebedtreatmentsystem.gif

Performance

Metals removal for iron and aluminum was >98%. Copper had removals of 50 to >99%, while zinc had removals from 5 to 65%. Manganese concentrations were generally unaffected. The effluent of the limestone reactor required post-treatment with lime to raise the pH high enough to remove zinc and manganese to dischargeable levels. The sludge from the limestone/lime treatment scheme had settled volumes that were 60% of the lime treatment alone.

Reference

Sibrell, P. L., T. R. Wildeman, M. Frienmuth, M. Chambers, and D. Bless. 2005. “Demonstration of a Pulsed Limestone Bed Process for the Treatment of Acid Mine Drainage at the Argo Tunnel Site.” Abstract. www.epa.gov/aml/news/argo.htm.


2. Bisbee No. 7 stockpile – BioSulphide process

Background

The Copper Queen Mine closed in the 1970s after nearly one hundred years of mining. One of the major issues at this site was drainage from a large ore stockpile (No. 7). This drainage was optimal for BioSulphide treatment due to its flow rate and copper concentration. The plant was commissioned in 2004.

Treatment Applied

BioteQ and Phelps Dodge have a Joint Venture to use the process to recover copper at Bisbee, Arizona. The fully commissioned BioSulphide® plant recovers copper from dump drainage. The resulting concentrate (50% Cu) reports to the Miami smelter for profitable water treatment. The plant has a design capacity of 3.6 tonnes Cu/day

BioSulphidePlantDiagram.gif


Performance

The feed water to the plant contains 0.5 to 2 g/L iron and 340 mg/L copper at a pH of 2.2. After treatment, the effluent contains less than 1 mg/L copper and iron. The plant is currently recovering more than 2 tonnes Cu per day.

Reference

Nelson L. Ashe, Ian McLean, and Max Nodwell. 2008. “Review of Operations of the Biosulphide® Process Plant at the Copper Queen Mine, Bisbee, Arizona”. In Hydrometallurgy 2008 - 6th International Symposium - Honoring Robert Shoemaker. Editors Courtney A. Young, Patrick R. Taylor, Corby G. Anderson - 2008 - Technology & Engineering - 1186 pages