Ore dilution and quality control in open-pit mines 1. Definition Dilution in the mining sector refers to the inclusion of sterile material that is not separated from the ore during mining operations and is extracted with the ore. This waste material mixes with the ore and is then sent to the processing plant, resulting in an increase in total tonnage and a decrease in average grade compared with the initial plan. 2. Internal and external dilution Dilution in mining operations can be internal or external. - Internal dilution: occurs inside a mining block in which pockets of waste rock cannot be separated and are extracted with the block; also when there is low-grade material surrounded by high-grade material. - External dilution: refers to waste rock outside the ore body that is extracted within the mining block. It varies according to the geology, the shape of the ore body, drilling and blasting techniques, the scale of operations and the size of the equipment. 3. Impact of dilution on the value of a mine One of the main consequences of dilution is the reduction in mill feed grade. A lower feed grade means lower revenues. For an ore of marginal grade, dilution can reduce the grades to such an extent that it becomes uneconomic to process, in other words, dilution can turn a block of ore into barren. So, as a result of dilution : - There will be a loss of material and the mine's overall reserves will decrease in a given pit. - The energy and materials used in the processing plant to process the waste rock portion of the feed are wasted. By Consequently, the unit operating cost of the crusher increases directly as a function of the dilution factor. 4. Some methods for controlling of ore dilution Dilution control is essential to maximise ore recovery and minimise unnecessary waste rock, which can have a significant impact on the overall profitability of the mine: - Accurate geological modelling and Knowledge of the ore deposit: improvements in the accuracy of geological models and knowledge of the ore deposit are required to accurately delineate the boundaries of ore and waste rock zones ; - Effective grade control: effective grade control procedures must be grade control procedures to accurately determine the grade of ore mined, thereby reducing the risk of dilution due to the mixing of high and low grade materials; - equipment selection and operation: use appropriate mining equipment mining equipment capable of selectively extracting ore without unnecessary dilution; - monitoring and reporting: implement comprehensive monitoring and reporting systems to track dilution levels and identify potential areas for improvement.