Automating water management for improved mining sustainability

Water is fast becoming a precious commodity, and mine water management has shifted from an operational expense to a strategic input.

Water scarcity is a global challenge with a highly localised impact — and the metals and mining sector is particularly vulnerable. As a swelling global population and heightened effects of climate change drain existing freshwater resources, water itself has become a precious commodity. Even as the metals and mining industry puts greater pressure on its own sustainable water management, a water shortage exacerbates challenges. Water consumption by the industry has increased with the decline of ore grade, and the energy transition has ramped up production demand.

In this current landscape, the conversation around water management has shifted from an operational expense to a strategic input. Simply put, no water means no production — and a slowdown of the vital mining industry would have drastic repercussions.

As the industry seeks to enhance its water management across the mine water circuit, water reuse and improved efficiency are clear solutions. Yet these solutions can only be implemented at their fullest potential — an optimised mine water circuit — if fundamental issues are resolved.

Using automation to improve data visibility

Today’s mine water circuits feature little to no automation. They are heavily reliant on manual data collection and operator experience to manage equipment control. The automation in use typically provides an overview of water circuit inputs and outputs, but little else. They therefore miss out on the potential of automation deeper in the circuit to help guide operations and enhance efficiency.

Wireless sensors, flow meters, valves, software and analytics help miners gain a full picture of how much water they use and what is being lost or wasted, while also streamlining and optimising control processes. Given the mining industry uses 1% of the world’s water, improvements in efficiency translate into lower costs for operators and big wins for local communities. A 2020 study from McKinsey and Company¹ predicts water-related operating expenses for metals and mining businesses will increase by a 1% to 4% compound annual growth rate by this year, with a 4% to 7% CAGR expected for water-related capital spending.

Smart field devices unlock more opportunities to save water

A higher level of visibility is vital for truly optimised operations, and a proven solution — smart field devices — is readily available. Smart field devices help improve data integrity by continually capturing critical data that can be analysed to identify optimisation opportunities.

Companies can leverage wireless instrumentation across remote areas of the mine to create a digital snapshot of the entire water infrastructure. Using a combination of wireless and wired instrumentation, automation enables mine operators to design water management programs that integrate real-time data to optimise the entire mine water circuit — accurately quantifying water inputs, losses, consumption and recovery.

Automating data collection can streamline regulatory reporting as well. Currently, miners report water withdrawal and discharge on a regular basis and aggregate it into an annual report. Automation empowers real-time data, simplifying the process and enabling faster, more transparent sharing of information.

For example, many mining companies turn to flow metering systems to meet local water requirements but are challenged by the high costs associated with stopping the process to add proper measurements as well as instrumenting huge pipes to account for high flow variability.

When reviewing different flow meter technologies, companies must ensure the flow meters are suitable for moist and dirty gases and for pipes with non-bonded liners. Also, for operations with large, 100 cm pipes, some flow metering technologies are heavy and difficult to transport and install at remote mining sites. The cost to shut down operations to install these technologies can be more than half a million dollars a day.

To address some of these challenges, companies turn to non-intrusive flow measurements that are mounted on pipes and use ultrasonic signals emitted alternately from one transducer to another. The physical quantities are determined by the transit times of the ultrasonic signals; the transit time difference being proportional to flow velocity. Microprocessors control the entire measuring cycling and verify signals for measurement usability and reliability, and noise signals are eliminated.

Figure 1: Non-intrusive ultrasonic flow metering.

In addition, many mines are turning to advanced electric valve actuators for remote tank applications, tailings networks and desalination plants, where the operation and maintenance of air systems for pneumatic valves is cost prohibitive. While electric actuators used to be less common due to torque limitations and electric power availability, the advent of much more efficient, high torque motors, spring failure options, robust diagnostics and wireless remote access has greatly changed the suitability and viability of electric actuators. The embedded controls and communication options enable remote control and monitoring of far-flung tailing distribution networks even when power is limited.

Reinforcing reliable water circuit operations

Water recovery is an important lever for a resource-intensive industry like mining, and automation can help drive significant efficiencies. Process control systems can be deployed to automate the mine water circuit, providing real-time visibility of water management operations, improving both operations and consistency of water recovery.

Advanced process control (APC) systems are also optimising key parts of the water circuit to boost water efficiency and recovery. At the same time, these technology solutions have significant potential to reduce tailings volume. Thickeners, charged with separating water from slurry or solid–liquid mixtures, are a prime example. Model predictive control technology helps address this by optimising the underflow rate based on density constraints while preventing rake damage. Using models of optimal performance and engineering simulations, APC can reduce production variability, making efficient utilisation highly replicable.

Another area where advanced analytics assists is in desalination plants. In water-scarce countries a greater focus on water recovery is vital, and in many countries the mining industry has turned to large desalination plants to sustain operations. By using sophisticated control systems, these plants are fully integrated into the wider mining ecosystem and offer 24/7 visibility of water management operations.

Though desalination is extremely effective in protecting freshwater resources, salt water is highly corrosive, increasing the necessity for intelligent and predictive equipment health monitoring, helping operators predict and prevent equipment failure and increased maintenance costs. In addition, analytics software provides critical pump health monitoring, helping engineers detect and avoid breakdowns with the aid of machine learning. Conditions such as cavitation, bearing wear, shaft misalignment, seal leaks and other damaging conditions are detected before impacting operation, and personnel are notified of what corrective action to take and how urgently.

Miners are constantly focused on extracting the greatest value from the raw materials they extract. That same stewardship and optimisation mentality is increasingly being applied to resources like water that are critical to their production processes. Mining leaders who adopt automated solutions for water management today are well-positioned to navigate waves of change well into the future, reducing costs while also freeing critical freshwater resources to support healthier communities around the globe.

^{1. McKinsey & Company 2020, Optimizing water treatment with online sensing and advanced analytics, <<https://www.mckinsey.com/industries/metals-and-mining/our-insights/optimizing-water-treatment-with-online-sensing-and-advanced-analytics>>}

Top image caption: Water treatment plant at a copper mine in Arequipa, Peru. Credit: iStock.com/tifonimages