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In the future, coupling APC solutions with those that harness AI and machine learning could offer unprecedented levels of process performance. (Photo: Schneider Electric)

E&MJ investigates the potential that advanced process control holds in improving the efficiency, productivity and sustainability of mining operations

By Carly Leonida, European Editor

Mining operations are under constant pressure to maximize their resource extraction while lowering energy usage, emissions, waste generation and water consumption. Advanced process control (APC) is one proven technology that offers a way to optimize recovery yields, lower energy consumption and improve product quality by automatically adjusting process variables based on real-time process data.

Marc Poualion, Industry Solutions Director, Metals & Mining at Aspen Technology, explained: “Mines are increasingly deploying sensors and collecting vast amounts of operation-
al data. APC not only leverages this data to identify patterns, predict process behavior and optimize control strategies, but can also provide real-time insights into process performance. This allows operators to quickly identify and address deviations from optimal conditions.”

Ahmad Aly, Global Commercial Leader for Industrial Automation and Software in Mining, Minerals & Metals at Schneider Electric, agreed: “The mining and metals industry has been using APC for over a decade, and it’s well known for its ability to improve yields, reduce energy consumption, improve productivity, and more. All these factors resonate with the larger themes that we’re seeing in mining and metals today around productivity and sustainability. I believe these two trends, coupled with the significant cost pressures that we’re seeing, align very well with what APC can deliver.”

In industrial applications, APC solutions comprise a suite of software which sits above basic process control systems. By automating responses to changes in inputs, such as conditions or feed, APC can deliver better consistency in outputs, like productivity. In contrast, basic controls often require a manual response when a certain set point is reached.

Aly gave a relatable example: “Imagine you’re driving a car and want to reach a destination within a certain timeframe,” he said. “The car is capable of driving at 100 kilometers per hour (km/h) but, if you exceed 100 km/h then you’ll get a speeding ticket, and if you drive too slowly then you’ll be late. Now imagine there are lots of people heading to the same destination and each has a different tolerance for safety when it comes to speed, so some will drive at 95 km/h, some at 98 km/h. That variability is down to the person who’s driving the car. However, if everyone used cruise control to drive at exactly 100 km/h, then their journey times would be more consistent, and no one would get a fine.

“APC is the process equivalent of cruise control. The variability that we see in mining and metals process performance is often down to the way in which human operators respond to changes in key parameters. Operating processes in a more consistent way on a large scale can lead to big increases in productivity and efficiency over time.”

What’s New?

Today, modern, best-in-class approaches to process control offer new adaptive workflows that enable faster APC model deployment. Adaptive technology enables more efficient maintenance of APC models that can accurately represent new process conditions and avoid loss of profits.

Poualion said: “APC is now a mature, proven technology. Commercial solutions have evolved to provide more self-guided, automated and intuitive workflows, enabling process control engineers entering the market to develop powerful controllers with minimal guidance. Thanks to this, a new generation of process control engineers are better positioned to fill the void in field expertise left by the retiring workforce.”

In the past, APC technologies were often costly and complex to implement, leading them to only be feasible for large organizations with expert personnel who could spend hours integrating, configuring, and maintaining the software within the plant’s control system.

“APC technology has matured but has also innovated significantly over the last 10 years,” Poualion told E&MJ. “End users are now able to develop high-order dynamic models within minutes from historical data.”

Similarly, actual plant performance changes over time due to issues, such as catalyst degradation, fouling, feed quality, and other factors. Today, these inputs can be modeled, and APC models are able to adapt to these new conditions. Poualion said that patented calibrate technology allows auto-step testing and offline model development, while the APC controller continues to optimize, and operations remain undisrupted. Modern APC systems can also offer virtual advisors that enable operations to be more self-reliant and make better control decisions in seconds.

He added: “Much of the complex engineering for control configuration and model identification is now performed via automated walkthroughs supported by industrial artificial intelligence (AI) that mines existing historical process data and automatically builds seed models.”

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Using APC to operate processes in a more consistent way can lead to big increases in productivity and efficiency over time. (Photo: Schneider Electric)

Where Can APC Add Value?

Poualion explained that APC solutions increase profitability and sustainability by modelling and understanding the relationship between manipulated and controlled variables to manage operational priorities and objectives. These priorities are translated into mathematical expressions via APC that will make decisions minute by minute to optimize the plant and equipment according to ranked objectives, such as increased production, increased profitability/margin, or minimization of emissions.

Common applications include crushing and concentration flowsheets, milling and grinding, and flotation circuits, through to downstream portions of the value chain, such as smelting. APC is also used heavily in adjacent industries, such as cement, which operate large kilns and mills.

Poualion gave some examples: “Adjusting agitation levels, determining ideal reagent dosage, optimizing water usage and creating more consistent processes in froth flotation plants, delivers meaningful impacts on productivity and sustainability,” he said. “APC solutions are similarly used to regulate pH levels using lime dosing in leach operations, and to optimize the spodumene-to-lithium carbonate yields by maintaining tight processing temperatures in lithium kilns.

“Similarly, APC solutions optimize surface area by controlling roaster temperatures for neutralization and leaching in gold concentrate roasters. They can also automatically coordinate underflow, recirculation, feed water, rake height and a host of other variables in thickeners.”

APC solutions can improve cyclone performance by stabilizing discharge density in crushing and screening; optimize feed supply, gas consumption and furnace operations in calciner operations; and balance steam header pressures to create more stabilized operations in steam and power generation. All these applications lead to better productivity and metal recovery, as well as sustainability through reduced water consumption and energy usage, all while minimizing costs.

Aly explained: “APC is usually used in processes where there are multiple complex and sometimes conflicting variables. As a concept, it’s been around for quite some time. Ten years ago, everyone was talking about expert systems, rule-based control techniques and fuzzy logic, and many of those early deployments still exist. But today, we’re seeing a shift towards model predictive control (MPC).”

MPC builds on the huge amount of historical data that mining and metals companies have available, allowing them to make predictions in variability which brings processes to a more stable state of operation. It does, however, require good quality data, and specialized engineers with specific scripting skill sets which are less common than, say, Python or JavaScript capabilities.

“One of the first things we do before embarking on a new APC project, is to look at the clients existing data,” said Aly. “It’s important to see which data points they do and don’t have, so that we can determine whether an APC system would be beneficial or not.”

Increasing Flotation Recovery in Oz

Together, Emerson and AspenTech offer complete coverage of the comminution, mineral processing and metal recovery segments of the mining value chain. Emerson’s solutions provide monitoring capabilities through sensors and a base control layer to generate critical mining process data. This empowers AspenTech’s APC solutions which ensure optimal operating conditions.

Dustin Beebe, Vice President of Performance Software at Emerson, explained: “Identifying key sensors and bringing those into control systems is vital to a successful APC project. You have to have the right data and the handles to optimize the process. Additionally, in mining we see that access to sensor level data, such as device alerts, provides insights into equipment and sensor health, which is key. Seamless integration with base level controls like those in Emerson’s DeltaV control system allows APC to be deployed to quickly capture benefits and reduce the cost of maintenance.”

An operation in Australia recently implemented Aspen DMC3 — AspenTech’s APC solution — as part of an upgrade to its froth flotation circuits. New flotation cells were introduced to the existing system with parallel lead and zinc recovery streams. Flotation variables, such as aeration rates, pulp levels and reagent dosing, required balancing at the conceptual stage and continual adjustment to determine impacts on downstream metals recovery. Once the solution was implemented, Aspen DMC3 delivered optimized processes for both lead and zinc recovery based on the new plant installation, leading to increased metal recovery and profitability.

With data-driven continual optimization sourced from plant historian data, metal recovery increased by 1.35% annually which, over the course of the full year, scaled to generate additional revenue of upwards of $2 million per year.

Saving Energy at a Chilean Copper Concentrator

Schneider’s suite of APC solutions and services encompass software and the toolkits and knowledge required to successfully deploy them.

“APC is a complex solution, and we have specialized engineers as well as after sales and customer support teams in key mining locations around the world, including Australia, Chile, China, the US and Canada,” said Aly. “An important service that we provide is benefit studies. Any company that’s considering investing in an APC system first needs to determine whether it would work given the state of their data and the returns they could potentially expect.”

Based on their findings, the team can then provide the client with a detailed projection of which areas could benefit from APC within their plant and the savings they could expect. The return on investment (ROI) can also be calculated based on energy consumption, fuel savings, improvement of yield, maintained quality, reduction of rejects etc.

“We can even go a step further and guarantee performance ahead of the implementation,” said Aly. “Writing it into a contract removes a lot of risk for the client and gives them peace of mind that the deployment will work.”

Schneider recently deployed an APC solution at a copper concentrator in South America. The plant uses cyclones for classification and the software was introduced to improve process efficiency and reduce recirculation to the mill, resulting in a 4%-5% energy saving in the mill.

“The client also saw additional benefits in productivity,” Aly told E&MJ. “Because now, they’re spending less time regrinding material and have reduced their water usage too.”

The Future is Integrated

In more complex applications, multiple APC models can be deployed to optimize processes against different objectives and constraints. “At a certain point in time, a mine might want to operate for maximum productivity, even though it’s going to require more energy,” explained Aly. “At other times, the mine might want to focus on lowering its operating costs. The optimizer functionality in modern APC systems gives operators the flexibility to optimize based upon their specific schedule, plan and key performance indicators (KPIs).”

In the future, coupling APC solutions with those that harness AI and machine learning (ML), either to orchestrate complete plant performance, or to solve adjacent challenges, could offer unprecedented levels of performance.

“It’s common to have multiple APC systems running within a plant,” said Aly. “But I haven’t seen an additional orchestration layer deployed yet. Enabling that would require input from business intelligence, and connection to planning and scheduling information. To give an analogy, it would be like the shift from cruise control to fully autonomous vehicles. This is where AI and machine learning could potentially add value in the future.”

He added: “Going forward, cost pressures on mining and metals companies are only going to increase. We’re seeing degredation of ore grades, which means that more effort needs to be spent to extract valuable metals. APC can help with that. We also see trends such as sustainability increasing in
importance due to the demand for energy transition minerals, like lithium, cobalt and copper, which power electric vehicles and renewables. And again, these put pressure on things like energy and water consumption, which APC can help optimize.

“The integration of different open control systems and the ability to connect an additional IT layer which taps into business intelligence and KPIs will allow even more efficient operations. I think APC can, and will, play a much more effective role in mining and metals operations when it’s deployed more widely. And if we can solve adjacent problems using AI and ML, then that will make for a very interesting business proposition.”

Poualion agreed: “By implementing APC solutions, mining operations will not only increase productivity and profitability, but will simultaneously become more sustainable in their daily operations. Those teams will more easily meet the sustainability objectives their organizations commit to. They will also continue to be granted social and regulatory license to operate by showing that they are invested in sustainability and commitment to the communities in which they operate.”

 

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