The analysis of coal indicates 60wt%C, 35%H, 2%S, and the balance noncombustible ash. The coal is burned at a rate of 300,000kg/h, and pure oxygen is fed with 5% in excess. All of the noncombustible ash and 20% of the carbon in the fuel leave the furnace as a molten slag; the remainder of the carbon leaves in the stack gas as CO and CO2; the hydrogen in the coal is oxidized to water, and the sulfur emerges as SO2. The selectivity of CO2 to CO production is 5:1. (MWC=12, H=1, S=32.1, O=16). Calculate the flow rate in ft3/min of oxygen not used in this process at 35 psig, and 68F.