An ideal metal removal treatment sequence for mine drainage water is a settling pond followed by treatment with an Octolig® MRP (Metal Removal Plant). Lime is added to the incoming drainage water to increase the pH to an optimum pH for Octolig® treatment. At the increased pH, high concentrations of heavy metals may produce some heavy metal precipitation in the settling pond.

After the addition of lime to the mine drainage water, the heavy metal concentrations remaining in the drainage water usually are greater than the permitted limits. Passing the settling pond's overflow through the Octolig® MRP consistently reduces the heavy metal concentrations to a fraction of a part per million.

Octolig® MRP system requires little maintenance and has low operating costs, which make it ideal for an economical metal removal treatment system for mines.

Leadville Drain

A large scale pilot plant was operated at the drainage tunnel near Leadville, Colorado. The primary contaminating metals in the drainage were copper and zinc. During the pilot test, a 100,000 gallon quantity of contaminated mine drainage water was Octolig® MRP treated. The average influent and effluent concentrations were:

Metal	Untreated Water	Octolig™ Treated Water
Cu	12.5 ppm	.29 ppm
Zn	7.2 ppm	.50 ppm

This plant-scale pilot test proves that Octolig® treatment reduces heavy metal concentrations to concentrations of parts per billion.

The Berkeley Pit

A large pilot plant test was conducted at the Berkeley Pit in Montana. The Berkeley Pit is an open pit that contains highly toxic water, especially toxic to wildlife. The main poisonous heavy metal is copper, but numerous other heavy metals are present. The pit water is quite acidic. Therefore, the pH of the pit water was raised to a pH of 8.3 to ensure optimum performance of the Octolig® MRP. Most of the heavy metals precipitated and were settled out of solution. In the “clear” overflow, some of the heavy metal concentrations were still above the permitted limits. Octolig® MRP treatment removed most of the remaining metals. The results were:

	Untreated Influent	Octolig® Treated Effluent
pH	2.5	8.3
Al	341 ppm	< 0.3 ppm
Cd	2.6 ppm	< 0.03 ppm
Cu	208 ppm	< 0.1 ppm
Fe	908 ppm	< 0.1 ppm
Mn	248 ppm	< 0.05 ppm
Ni	1.3 ppm	< 0.1 ppm
Zn	703 ppm	0.1 ppm

The pilot plant test demonstrated that the Octolig® MRP treatment reduced heavy metal concentrations to “parts per billion.”

Projected Costs of a Full Scale Berkeley Pit Treatment:

Summitville

At the Summitville mine near Del Norte, Colorado, an on-site pilot plant was operated on the drainage water from the cyanide destruction process (CDP). The CDP was for the destruction of the cyanide in the leach pit water. In the normal operation of the CDP, hydrogen peroxide was added to the basic solution, then the precipitated heavy metals were filtered out. At a pH of 10.3, the CDP effluent was passed through the Octolig® MRP. The concentrations of the heavy metals were:

	Untreated Influent	Octolig®Treated
Al	1200 ppm	.18 ppm
Cd	.6 ppm	< .001 ppm
Cu	100 ppm	< .013 ppm
Fe	1250 ppm	< .006 ppm
Mn	120 ppm	.048 ppm
Ni	4 ppm	N/D
Zn	80 ppm	< .001 ppm

In conjunction with simple pH adjustment and consequent precipitation, the Octolig® MRP treatment reduced heavy metal concentrations to the parts per billion range.

A Colorado Gold Mine

An Octolig® MRP is currently being installed at a gold mine located in the mountains west of Denver, Colorado. Although, the mine is a gold mine, the primary contaminating metal in the mine drainage water is zinc. The mine discharges 4 million gallons of mine drainage water per year. Lime is added crudely to the mine drainage water as it flows into a 33 ft. by 40 ft. by 3 ft. deep settling pond. The overflow from the settling pond will be pumped continuously through the Octolig® MRP. During the pilot test, the Octolig® MRP treated water contained 0.2 to 0.6 ppm of zinc. Operating costs of this installation are less than $ .70 per 1000 gallons of drainage water.