The following flotation reagent mixing system is typical for the flotation reagent mixing systems: A-208, Xanthate and Sodium Silicate.
The reagent mix tanks, for the above mentioned reagents, are located on the basement floor. Feed chutes from the main operating floor carry dry or wet reagents to each mix tank. Either reclaim or fresh water is added to the mix tank with the reagent, the reagent is mixed with an agitator, and then it is pumped up to its respective day tank on the upper operating floor for distribution. Parallel metering pumps regulate the flow of the reagent from the holding tank to the various feed points. One pump is run while one pump is generally held on stand by. An overflow line from the day tank allows flow back into the mixing tank. Pressure gauges are mounted near the bottom of each mixing tank, and have been calibrated to indicate level in the tanks. Pressure gauges have been installed at the transfer pump discharge lines. The holding tanks have level gauge glasses and high level float switches, the latter alarming the mill control panel annunciator. The 110 volt starters for the metering pumps are located in the mill control panel, rather than in an MCC, and are locally controlled. However, the pumps can be stopped from the control panel, and on/off pilot lights on the control panel indicate operation for each set of parallel pumps.
MIBC (methyl isobutyl carbinol) is supplied in liquid form in 45 gallon drums. MIBC is pumped directly to the process with one of two 1/8 HP drum pumps. Control of the MIBC flowrate is performed by needle valves at flowmeters located at the respective addition points discussed.
Reagent mixing system for sodium metabisulphite is identical to that described for the flotation reagents. Sodium metabisulphite is delivered to the first or second conditioning tanks with metering pumps.