The mining industry uses technology to optimize production

The benefits of modernization were the focus of this week’s Mining & Metals Industry Forum at Automation Fair 2022. Attendees first learned how Chicago Heights Steel has benefited from modernizing its aging control systems. Then, learn how mining companies around the world can become more sustainable by taking a second look at traditional grinding technologies.

Moderator Mauricio Alfonso, Industry Process Director at Rockwell Automation, first welcomed the panelists to Antonio Ambra, Managing Director for North America at AIC; David Zapata, general supervisor of engineering at Chicago Heights Steel; and Gillian Holcroft, President of ReThink Milling and Innovation Manager at the Canada Mining Innovation Council.

Ambra and Zapata first took the stage to outline a production system upgrade at Chicago Heights Steel with the help of AIC, a power controls provider and systems integrator.

Chicago Heights Steel was founded in 1893 and is now the largest specialty market plant in the United States. The facility recycles rail steel into many products for farms, ranches, communities and construction sites, including fence T-posts, U-channel posts for signs, or other custom-designed products. The plant takes the rail steel and splits it into three sections (the head, the web and the flange/root) at high temperatures. Each part is rolled to a predetermined shape and size by a series of rollers. “We’re releasing a different product from each of these sections,” Zapata said.

The plant had many reliability problems. Equipment kept failing without warning and diagnosing problems was nearly impossible, all resulting in significant lost production. In addition to improving automation reliability and diagnostics, the project also had to include a new open system that would allow later modifications; reduce maintenance costs for spare parts and downtime; maintaining a constant production and milling capacity; and install an integrated and comprehensive control network infrastructure.

“The distributed control system (DCS) we had at the facility was very outdated and had very little feedback,” said Zapata. 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,” said Zapata, beginning to work with AIC. “We’re very hands-on at Chicago Heights Steel,” he said. “I’m going with my boys. I put my hands on the gear with them. And we chose AIC because they had the same mentality. They were basically able to come in with us and find the solution.”

The solution included a ControlLogix control system and other Allen-Bradley components from Rockwell Automation. The AIC Rolling Mill Automation and Control System (RACS) solution has been installed in more than 50 plants around the world. The solution also uses Rockwell Automation’s HMI FactoryTalk View SE, another product that AIC is very familiar with. The plant’s two production lines were kept separate. “So that one day the work can roll on a single line,” said Ambra. “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 B. Security door options and Arc Detectors. Also, operators with a downstairs locker can request access to a machine and the mill will stop automatically. Then the operator can access the required key. “Once the key is out, we make sure everything in the closet is turned off,” Ambra said.

With only 10 days for the project to be commissioned on site during an annual shutdown, AIC relied on Rockwell not only during design to help properly configure the network, but also at the panel fabrication facility in Italy to test the products on site before shipment.

With the new system, after only three months of rolling, the performance increased by 15%. “This gives an idea of ​​how much time the plant lost with the old system before,” Ambra said. The plant also produces much less steel scrap from its new production process.

Disruptive technology for grinders

In the second Industry Forum presentation, Holcroft outlined a pilot project to develop a conjugated anvil hammer mill (CAHM) platform technology that has the potential to reduce energy consumption by 65% ​​compared to high pressure roller mills (HPGRs).

Holcroft outlined the work 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 industry issues and focuses on disruptive technologies. “If we pool our resources, share risks and share rewards, maybe we can achieve something great,” Holcroft said. Four years ago, she began leading the project.

Mining consumes between 3 and 6% of the world’s energy. “The grinding equipment hasn’t evolved at all in the last 20 years, with the last major advancement being a high-pressure milling drum,” said Holcroft.

The consortium responsible for advancing new grinding technologies includes CTTI, the inventor and product developers, Anmar as manufacturing partner, Corem as testing expert and Rockwell Automation as automation partner. The consortium also includes a number of mining partners who are investing resources and funding to advance the project. It has the potential to significantly reduce operating and capital costs for grinding operations. “And of course, with all of these things combined, we can have a huge impact on environmental, social and governance (ESG) and decarbonization goals,” Holcroft said.

The project has so far had an investment of US$11.9 million. “If you’re looking for government grants and you see big miners putting money behind it, that must be good,” Holcroft said.

The key innovation is the unconstrained fracture of thin particles, which is a more energy efficient method of rock fracture and works for all hard rock and most soft rock mines. The energy benefits come from eliminating small rock crushing and compression and shear fractures, maximizing voids that allow crushed rock to expand, and minimizing wear through synchronized crushing surfaces. There is very little material jamming in the machine. “The hammer pushes the material out of the slot once it’s fine enough,” Holcroft said. It eliminates displacement and significant fines, and maximizes voids in the material. “The novelty is maintaining a thin bed of particles,” Holcroft said.

As soon as the material leaves the CAHM, it enters the MonoRoll, which is intended to replace the ball mill. “The combination circuit of the future would not have recirculated pebble crushers or hydrocyclones. All of the screening happens inside the machine,” said Holcroft. “Less equipment means lower operating costs.”

The design was optimized by CTTI based on Discrete Element Method (DEM) modeling. “They tweaked over 200 simulations to figure out what the angle of the tooth, hammer and anvil should be,” Holcroft said. “They optimized this slot geometry to maximize energy efficiency and minimize wear. So before we even designed or built anything, they had simulated everything.”

This was necessary in part because the machine is massive. It weighs 27 tons. It is 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 conduct experiments on the prototype to determine limits on capacity, power reduction, reduction ratios, and product size distribution. They anticipate further machine updates can achieve 72% energy savings compared to HPGR, as well as a superior product and higher reduction ratio in a single pass.

“Because of the way this machine is designed and the hydraulics that apply forces to crush the rock and compress the hammer and anvil, if we get into a metal-in-the-machine situation, the hydraulics have to react locking onto this event in less than 10 milliseconds so as not to damage the liners in the machine,” said Holcroft.

The technical team wants to track 150 analog, digital and vibration inputs at 200 Hz and respond to events within milliseconds. “At 5 milliseconds, we’re really at the sensor and hardware limit,” said Holcroft. Rockwell’s FactoryTalk Edge Gateway and AC drives helped, she added.

ReThink Milling wishes to become a licensor of the CAHM platform technology to one or more Original Equipment Manufacturers (OEMs). Holcroft said the project still requires additional strategic mining partners and funding and hopes to go commercial with one of the consortium mining company partners.

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