Figure 1: The copper electrolysis operations at Kidd Creek
Introduction
The Kidd Creek Metallurgy site processes the copper/zinc ore from the Kidd Mine site located 7km away. The metallurgy site has a copper smelter and refinery, a zinc refinery, and indium and acid plants.
The mine and metallurgy site are owned and operated by Falconbridge Ltd, a large Canadian mining company.
The Thickened Tailings Site
In 1973 the Falconbridge owned Kidd Creek Metallurgy Plant in the town of Timmins, Ontario, Canada was the first site to use thickened disposal of tailings. The theory was that instead of having a conventional impoundment involving embankments that are continually raised as more tailings are disposed of, there would be little or no embankments at all.
The Kidd Creek thickened disposal site currently stores >100 million tonnes of base metal sulphide tailings and by the time the site is expected to close in 2023 >130 million tonnes will be stored. The radius of the conical pile is 1.2km and the height of the cone is 25m. The height of the cone increases by 0.2m/y and by closure the height is expected to be 29m.
The reasons for thickened disposal at Kidd Creek instead of conventional impoundment storage are mainly due to the topography, hydrology and soil conditions of the area.
- High dykes would be unsuitable for the area and the risk of instability would be increased due to the extremely poor soil conditions.
- The tailings are finely ground (45µm) and imported materials would have to be used for dyke construction, thus increasing costs.
- Predominantly cold climate conditions would only allow a short window for dam construction.
- The site is
situated on high ground surrounded on three sides by Porcupine River
tributaries.
