A methodology is presented for deciding the location of a third ore crusher to be installed at Chile’s Chuquicamata copper mine. The proposed approach determines which location alternative exhibits the minimum capital and operating costs when equipment failure probability is considered. Two alternative location configurations are evaluated using the stationary probabilities of a Markov chain model, and the results are validated with a discrete-event simulation model. The Markov model generates insights into the relationships between the variables that a discrete-event simulation cannot provide, and does so without the latter’s greater costs and complexities of modelling, solving and calibration.

In the design of open pit mines, the region to be mined is partitioned into pushbacks, subregions that allow the mining to be divided into distinct phases. Practical pushbacks are connected, satisfy a minimum width for mining equipment and include a haulage ramp. Current pushback models typically relax some or all of these mineability conditions; consequently, the outputs from those models require significant intervention by mining engineers. We present a formulation to generate maximum value practical pushbacks. A closeness factor is introduced to quantify the design’s mineability. Finally, a case study of a real mine shows that our model can produce pushbacks with more practical designs and better value than traditional approaches.

The assessment of mineral surface hydrophobicity at the industrial scale is a challenge. In some industrial situations, such information is indirectly obtained from other proxy variables. A well-known example of this is observed in the Cu-Mo selective flotation operation, where sodium hydrosulphide is used to change the redox potential and, controlling this value, determine when Cu-sulphide floatability is inhibited. Preliminary experiments indicate that this reagent may also promote the formation of solid precipitates, reducing its impact on the redox potential. This study aims at designing a simple strategy at the laboratory scale to report and quantify NaSH losses due to parallel, irreversible, and/or fast reactions, such as precipitation. Experiments carried out using process water coming from a Cu-Mo selective flotation plant in Chile show that departing from different pH conditions and the addition of hydrosulphide ions effectively triggers the precipitation of specific metal ions, decreasing its availability to reduce the redox potential of the aqueous solution. For this specific case scenario and water quality, around 5% of the NaSH dosed precipitated. An SEM-EDX analysis of the produced solid phase shows that it is composed of mainly iron sulphide and hydroxide, along with other metal hydroxides. More importantly, it was found that dosing the reagent at the same concentration, but in the form of small increments, allows reaching the redox potential more efficiently, reducing to some extent the precipitate production and the unnecessary NaSH consumption in up to 30% of the NaSH dosed. Preliminary 1-D modelling of the process, based on mass transport coupled with reaction mechanisms, provided a first indication of the best dosing conditions for this reagent. The latter is expected to contribute to the development of better and improved reagent dosage technologies in froth flotation environments.