Molybdenum Flotation Cell Replacement

Project Description:

Value of the project: $ 3,000,000

The existing two banks of Denver flotation #100 (eight cells each) had reached the end of their useful life. It was decided to replace them with Outokumpu (OK) Tank Cells #10 (eight flotation cells in two banks). Our design approach is to make the changeover with minimal disruption to the production of Moly. The existing structural support steel was used and reinforced. The tank cells were covered with lids to contain the H2S gas. A manifold connected with ductwork to a new scrubber. The cells will be supplied with NaHS, N2, and Co2. The two Conditioning Tanks upstream of the cells needed to be raised to accommodate gravity flow. Pump boxes (two) and pumps (four) were added to the floor level below the cells to pump concentrates to the thickeners.

Scope of Work:

Sacré-Davey was required to complete a condition assessment of the structural steel supporting the existing Denver flotation cells and to re-engineer the floor system incorporating some of the existing structural steel to support new Outokumpu Tank Cells

Challenges:

Much of the existing structural steel was corroded and could not be re-used. The change over from the Denver to Outokumpu flotation cells was required to be completed with minimum downtime.

Solutions:

After completing our assessment of the existing structure, it became obvious that rebuilding the floor could best be expedited by keeping (and strengthening) the primary beams on the major baylines and infilling between the main beams with new secondary members. Most of the existing secondary members were removed and replaced with new steel repositioned to suit the arrangement of the Outokumpu cells.

Achievements:

The work was completed with minimum downtime and minimal changes during construction.