RECOVERABLE RESERVES EVALUATION OF A PHOSPHATE DEPOSIT THROUGH OREBODY MODELING AND SELECTION PROCESS SIMULATION

This article describes a procedure for calculating the recoverable reserves od stratified orebodies characterized by a thin and irregular layers. An application on the phosphate deposits in the N’Zeto region of the Popular Republic of Angola is also described. The procedure consists in building a block model of the deposit though the conditioned multivariate geostatistical simulation of small areal units. The recoverable reserves are then calculated and defined by applying to the model a selection process based on measured geological/economic parameters taken from the drill holes: thickness of overburden and mineralized layers, economic grain-size fraction, grade. The procedure also takes account both of the geometrical constraints of the mining method and dilution. For reasons of confidentiality, a multiplier has been applied to the values adopted for the sampling data.