$5$inc is to be extracted from a roasted ore. All zinc is present as $ZnS{O}_4.$ Roasted ore of the following composition is obtained: $ZnS{O}_{4}18$ percent; gangue $75$ percent; moisture $7$ percent. The roasted ore at a rate of $25$ ton $h^{-1}$ is extracted with pure water. The resulting solution containing $12$ percent $ZnS{O}_4$ represents a $100$ percent recovery of the $ZnS{O}_4.$ One ton of inert gangue will carry with it $2$ tons of solution. Calculate the $lb,h^{-1}$ of water required.