Optimal mining of a stratiform phosphate field

An optimal control model is developed to determine optimal surface mining operations of a phosphate field. This field1806 1040 contains both a bottom layer and a top layer of phosphates. The deeper the digging, the more phosphates will be exploited but the higher will be the cost per ton. If the bottom layer is not exploited, it will be lost to future production. The methods of Optimal Control Theory are applied and produce expressions which can be evaluated for the optimal scheduling around the phosphate field.