Abstract

Establishing a reliable supply of process water in underground mining operations is one of the main challenges impacting mining operations globally. Underground water shortages are far too common, in most cases water shortages occur daily, costing millions annually in lost production. Vale recently experienced water supply constraints at Totten Mine in Sudbury, Ontario. Water shortages were causing operational shutdowns, as revenue generating equipment did not have a reliable source of water.  To improve operational efficiency at the mine, the team at Vale began investigating a new approach to water management.

A traditional installation allows water to flow through several PRV stations on its way down the shaft, known as a cascade system. Most pressure reducing valves (PRVs) in use today are pressure regulating valves, which allow for the outlet pressure to be set and adjusted. At Totten mine, regulating PRVs were installed, and the valves were struggling to keep up with system pressure changes, sudden flow changes, and increasing water demand. This, combined with valve droop, was the root of their underground process water delivery issues. 

To avoid shutdowns due to process water delivery constraints, Vale began to deploy a new approach to system design. This new strategy quickly began to eliminate fluctuations in water pressure and availability, mitigating costly water shortage or surge situations.

The first step was to separate the main water supply from the underground levels to create a cascading standpipe.  This involved removing the traditional pressure regulating valves from the system and replacing them with ratio valves. Unlike regulating valves that have a calculated output pressure, ratio valves operate on a fixed ratio pressure, so there is no set pressure on the outlet side of the valve. Vale’s initial installation involved retrofitting their current system design with new valves, but they quickly realized that their system design would have to be updated to allow for a complete elimination of water supply concerns. To avoid future shutdowns due to inconsistent water supply, Totten Mine implemented a system design change involving ratio and regulating PRV’s to deliver optimal water supply to both the shaft and the underground levels. Since the implementation of this new system design, Totten Mine has remained operational, with no system shutdowns due to water supply.

This presentation will review the challenges associated with the current design of many underground process water management systems and review a new approach to system design to alleviate the long-term challenges associated with inconsistent water supply. We will discuss into the solutions implemented at Totten Mine, and the value of a high-performance underground process water system.  Using the Vale case study, we will highlight true productivity gains realized within a mine that has employed this new approach to process water management.

Biography of the presenter