The mining industry leverages technology to optimize production

The benefits of modernization were featured prominently at this week’s Mining & Metals Industry Forum at the 2022 Automation Fair. First, attendees learned how Chicago Heights Steel benefited from modernizing its aging control systems. So how mining companies around the world can become more sustainable by taking a second look at traditional milling technologies.

Moderator Mauricio Alfonso, director of industrial processes at Rockwell Automation, welcomed the speakers Antonio Ambra, managing director for North America of AIC; David Zapata, general supervisor of engineering at Chicago Heights Steel; and Gillian Holcroft, president of ReThink Milling and head of innovation at the Canada Mining Innovation Council.

Ambra and Zapata took the stage first to outline a manufacturing system upgrade at Chicago Heights Steel, with help from power control system supplier and systems integrator AIC.

Chicago Heights Steel was founded in 1893 and today is the largest specialty market mill in the United States. The plant recycles rail steel into many products for farms, ranches, municipalities and construction sites, including fence posts, U-posts for signs or other uses. products. The plant takes the steel from the rail and splits it into three sections (the head, the core and the wing/foot) under high heat. Each part is rolled to a predetermined shape and size by a series of rolls. “We pull a different product out of each of these sections,” Zapata said.

The plant had many reliability problems. Equipment was constantly failing without warning, and diagnosing problems was nearly impossible, resulting in significant losses in production. In addition to improving automation reliability and diagnostics, the project also needed to accommodate a new open system that would allow for changes down the line; reduce maintenance costs for spare parts and downtime; sustain constant production and milling capacity; and install a complete integrated control network infrastructure.

“The distributed control system (DCS) we had in the plant was very old-fashioned with very little feedback,” Zapata said. Most of the equipment had reached the end of its useful life and spare parts were no longer available. “When I took over the electrical department three years ago, I was tasked with finding a solution,” Zapata said, and began working with AIC. “At Chicago Heights Steel we are very hands-on,” he said. “I go with my boys. I got my hands on the equipment with them. And we chose AIC because they had the same mentality. They were pretty much able to go in there with us and figure out the fix.

The solution included a ControlLogix control system and other Allen-Bradley components from Rockwell Automation. AIC’s Rolling Mill Automation and Control System (RACS) solution has been installed in more than 50 mills worldwide. The solution also uses the Rockwell Automation FactoryTalk View SE HMI, another product well known to AIC. The two production lines of the plant were kept separate. “So one day the mill can roll in one row,” Amber said. “It’s also a system that allows for expansion.”

The previous configuration was dangerous for operators, and the new panel design included many safety features, such as options for safety doors and arc flash detectors. Also, with a lockbox on the main floor, operators can request access to a machine and the mill will automatically stop turning. Then, the operator can access the necessary key. “When the key is out, we’re making sure everything is turned off inside the closet,” Amber said.

With just 10 days to commission the onsite project, scheduled during an annual shutdown, AIC relied on Rockwell not only during the design to help configure the network correctly, but also at the panel manufacturing facility in Italy to test the products before they were shipped to the site.

With the new system after just three months of rolling, performance increased by 15%. “This gives you an idea of ​​how much time the mill lost before under the old system,” says Ambra. The steel mill also produces significantly less scrap steel thanks to its new manufacturing process.

Disruptive technology for grinding equipment

In the second Industry Forum presentation, Holcroft outlined a pilot project to develop the conjugate anvil hammer mill (CAHM) platform technology, which has the potential to reduce energy consumption by 65% ​​compared to high-speed grind rolls. pressure (HPGR).

Holcroft detailed the work being done to develop CAHM and how the Canada Mining Innovation Council consortium is supporting the project. Her work with CMIC helps encourage mining companies to work together to solve common problems in the industry and focuses on disruptive technologies. “If we pool our resources, share the risk and share the reward, maybe we can make something great,” said Holcroft. You started managing the project four years ago.

Mining consumes between 3 and 6% of the world’s energy. “Grinding equipment hasn’t progressed at all in the last 20 years, and the last big advance was a high-pressure grinding roll,” said Holcroft.

The consortium charged with promoting the new grinding technology includes CTTI, the inventor and product developers, Anmar as manufacturing partner, Corem as test experts and Rockwell Automation as automation partner. The consortium also includes a number of mining company partners, who are investing resources and funding to move the project forward. It has the potential to significantly reduce capital and operating costs for grinding operations. “And of course, with all of these things together, we can have a big impact on environmental, social and governance (ESG) and decarbonization goals,” Holcroft said.

The project has $11.9 million in investment to date. “When you look for government grants, if they see that there are big mining companies putting money behind this, it must be good,” Holcroft said.

The key innovation is unconfined fine particle breaking, which is a more energy efficient way to break rock and works for every hard rock and most soft rock mines. Energy benefits come from eliminating small rock crushing, compression and shear fractures, maximizing voids that allow crushed rock to expand, and minimizing wear with synchronized crushing surfaces. There is very little material blockage in the machine. “The hammer pushes the material out of the crack as soon as it’s fine enough,” Holcroft said. Eliminate crackdowns and significant fines and maximize material gaps. “The novelty is in maintaining a bed of fine particles,” Holcroft said.

Once the material leaves the CAHM, it enters the MonoRoll, which is designed to replace the ball mill. “The combined circuit of the future would not have recirculating pebble crushers or hydrocyclones. All screening takes place inside the machine,” Holcroft said. “Less equipment means lower operating costs.”

The design was optimized by CTTI based on discrete element method (DEM) modeling. “They did over 200 simulation optimizations to figure out what the angle of the tooth, hammer and anvil should be,” Holcroft said. “They optimized the geometry of the crack to maximize energy efficiency and minimize wear, so before we designed or built anything, they had simulated everything.”

This was necessary in part because the car is huge. It weighs 27 tons. It measures 8.5 meters long, four meters wide and six meters high and processes 50 tons of rock per hour. Hot commissioning of the prototype was underway in August 2022. They are performing experiments on the prototype to determine the limitations of capacity, power reduction, reduction ratios and product size distribution. They predict that further upgrades of the machine can achieve 72% energy reduction compared to HPGR as well as superior product and higher reduction ratio in a single pass.

“Because of the way this machine is designed and the hydraulics driving forces to crush rock and force the hammer and anvil together, if we are in a situation where we get metal trapped inside the machine , we need the hydraulics to react to that event in less than 10 milliseconds in order not to damage the machine coatings,” Holcroft said.

The engineering team wants to track 150 analog, digital and vibration inputs at 200Hz and react to events within milliseconds. “At 5 milliseconds, we’re really at the limits of the sensor and the hardware,” said Holcroft. Rockwell’s FactoryTalk Edge gateway and variable speed drives helped make that possible, she added.

ReThink Milling wants to license the CAHM platform technology to one or more original equipment manufacturers (OEMs). Holcroft said the project still needs additional strategic mining partners and funding and hopes that a commercial launch could occur with one of the consortium’s mining company partners.

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