Vale Inco Operations At Thompson Grande Dame Gets Facelift

The grande dame of nickel mining in Manitoba is getting a facelift. Projects are underway to reduce particulate emissions from the smelter, automate the nickel refinery and create a more sustainable tailings area.

The $82-million smelter project is only the latest (and largest) in along line of improvements over the last 30 years. Particulate emissions, which totalled 11,900 tonnes in 1992, will be reduced to below the target of 735 t/y from 2009 onwards.

Key to accomplishing the reductions were the installation of a new Lurgi electrostatic precipitator (ESP) and upgrades to the associated dust handling equipment. The second phase included an upgrade of the existing ESP and its dust handling system which was completed in February 2009.

The modernization of the nickel refinery carries a price tag of $116 million and includes sophisticated automation equipment, the first of its kind for Vale Inco’s Manitoba Operations. The technology to be installed includes six-axis robots and other robots automatic cranes and electric-powered transfer cars. The aim is to improve working conditions in the refinery by eliminating the most strenuous and repetitive manual tasks.

The first station in the shear shed was commissioned in July 2008. The remaining equipment -in the starter sheet preparation area, anode processing area, anode and cathode delivery systems, rounds stripping area, cranes and plating tanks – will be installed in stages until the project is complete in January 2011. The need for automation is apparent when considering the refinery produces 130 million lb of nickel each year.

No modern mill can operate successfully without a sustainable tailings management area (TMA). The latest steps to create a facility that will support the Manitoba Operations for the foreseeable future is underway. When complete, the improved TMA will contain waste that has been pretreated to reduce heavy metals content behind taller dams.

Phase One of the TMA project began this year with the installation of two new pumping stations at the mill and 14-km of new, narrower pipeline to the impoundment area. Process changes are being made to sharply reduce water consumption in the mill. From the current rate of 6,000 to 6,500 US gal/min (gpm), water use will be reduced half the time to less than 1,500 gpm. In winter, water consumption may rise to 4,000 gpm over short periods to prevent the tailings line from freezing.

The construction of an effluent treatment facility (silo, lime slaker, slurry storage tank and sump pumps) will aid in raising the pH and neutralizing acidity. Lime addition is also expected to promote the settling of solids, shortening the period of time until reclamation. The final planned project for Phase Two is to build three nickel treatment solids containment cells in the TMA to assist in heavy metals removal.

The third and final phase of the tailings program involves raising the height of the three existing dams to expand capacity. They will be raised to 206 metres to contain tails from future production. Also during Phase Three, the South Beach tailings area will be covered and revegetated.

Mining and milling

Vale Inco’s Manitoba operation is currently exploiting the Thompson and Birchtree underground mines. At the end of 2008, the two mines contained proven and probable reserves totalling 24.5 million tonnes at 1.78% Ni. Both mines are developed for vertical block mining with limited cut and fill methods used for remnant mining.

The Thompson mill treats about 15,000 tonnes of ore daily. The flowsheet features conventional rod and ball mill grinding, cyclone separation and banks of rougher and scavenger cells. The rougher underflow is treated in a copper-nickel separation circuit to produce a nickel concentrate that is combined with the scavenger underflow and piped to the smelter. Small amounts of copper concentrate from the underflow of the separation circuit is piped separately to the smelter.

The Thompson concentrates and concentrates from the Voisey’s Bay mill in Labrador provide feed for the smelter and refinery.

The future

The residents of Thompson, Man., can look forward to many more years of operation from the Vale Inco mines, mill and smelter. And that future will be environmentally cleaner, healthier and more productive, making the province’s third largest city one of the better places to live Manitoba.