Controlled Recirculation Investigation At Ruttan Mine

A description is given of the investigation conducted at Sherritt Gordon's Ruttan Operation in Manitoba during 1986. Gas and dust concentrations were measured in the exhaust air of the major working sections to assess the potential for recirculating exhaust air into the intake air in winter to reduce heating costs. The results indicate that there is excellent potential to significantly reduce winter heating costs by controlled recirculation of exhaust air. Gas and dust concentrations vary significantly during the working shifts but have consistent trends from shift to shift and day to day. The variations in gas concentrations have similar trends but no single gas could be reliably used to predict the variation of the other gas or the dust concentrations. Dilution and the other effects which reduce pollutant levels as the exhaust air returns to surface indicate that recirculation should take place as close to surface as possible, subject to the economic constraints of the airway construction required and the extra fan energy required for the longer recirculation path. Recommendations are made for the choice and positioning of air and dust monitoring sensors and the logic of a control system. Economic analysis of the results indicates that controlled recirculation is viable at an existing mine with a pay back period of approximately two years. Incorporation of a system into a new mine at the planning stage would significantly shorten the pay back period.