MechChem Africa April 2018

Endress+Hauser offers tailored solutions and services for every phase of the life cycle of a project, from measurement point design, automation system programming and SIL-based commissioning, to on-site calibration and training. In this article, the company indicates how to comply with environmental laws and lower costs by advancing mine water treatment processes. Better results for mine water treatment

A ccording to the International Council ofMining andMetals, mining companies viewed water like any other production input. But this has changed in recent years. Water scarcity is a growing challenge in the mining environment. Mining requires water at almost every stage of the process and the bulk of the assets of major mining companies are in water-stressed regions, mostly in the southernhemisphere. Formanymining companieswater is being considered as a strategic resource where in the past it was only about rocks. Water plays a crucial role for mining operations. Not only do the people working in mines depend on it but also mining processes con- sume an average of 10M ℓ of water a day. The preparation of thewater used in processes such as leaching or flotation consumes energy and chemicals. Finally, mines must discharge the used water back into the environment without harming it, in accordance to local standards and in conjunction to the mine’s water use license. As a lot of mines are situated in remote areas without sufficient access to water, this can be a problem. This is why more and more mines rely onwater extractionprocesses such as reverse osmosis (RO) to secure their water supply, but these processes should be closely monitored to ensure consistent results. The same goes for the preparation of municipal or industrial water. Whereverwater treatment is used, tight control of parameters such as pHanddissolved oxygen enables the usage of energy and chemicals to beoptimised,whilemakingsureenvironmentalregulationsarefulfilled.

A schematic diagram of a typical reverse osmosis water treatment solution.

Reverse osmosis is one of themost common treatment techniques for minewater. It relies on filtering water through special membranes. The challenge is to have filtration cycles as long as possible without harming the membranes, which are prone to blockages, fouling and scaling. Therefore, besides flow, the most important parameter on the inlet is the differential pressure measurement across the filter.

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A schematic diagram of a typical municipal wastewater and sludge treatment solution.

28 ¦ MechChem Africa • April 2018