A Two-Fold Control Solution
Successful operation of the ore loading system depends on the coordinated control of the ore chutes and haulage vehicles. Variant is charged with supplying the ore chutes – and a safety control system that meets functional safety requirements. To achieve a functionally safe system, in this case a system that meets SIL 3 ratings, the design considered the process that encompasses the bin, chutes and trucks.
The control system is built on a Rockwell Automation® platform featuring Allen-Bradley® Compact GuardLogix® safety controllers, Allen-Bradley POINT Guard I/O™ modules, and HMI based on Allen-Bradley PanelView™ graphic terminals.
The system is designed with a GuardLogix controller and HMI in each chute and aboard each truck. For fail-safe communication, the integrated system uses the CIP Safety™ protocol running on an EtherNet/IP™ wireless network.
“We have a history of working with Rockwell Automation during our design process,” Meloche said. “We’re a relatively small company developing state-of-the-art solutions, so we rely on the core competence of our larger group of companies and supply chain to support the development our solutions.”
Enabling Smart Technology
To optimize the system, Variant incorporated several technologies that are not new in other industries but new to underground mining. For example, the vehicle detection system in the chute loading area detects a truck’s presence and position – while RFID technology determines the vehicle model and type.
“This technology – and CIP Safety over wireless – allow operators in the truck cabs to control the chutes in a safer manner,” Meloche said. “The chute will not operate unless a haulage truck is present and in the correct position. Jeeps or other vehicle types cannot trigger operation.”
The system also includes fallen object protection. A gate at the end of the chute contains any loose rocks from the previous load to help safeguard approaching vehicles and personnel.
“And our system monitors the ore bins associated with each chute to make sure they don’t run empty,” Meloche said. “We keep material in the bins at all times to serve as a buffer – so ore falling 150 feet doesn’t come out of the chute like a rocket.”
On the mechanical side, Variant designed the chute with a large, 5’ X 10’ (1525 mm X 3050 mm) opening to improve throughput and minimize the risk for hang-ups.
Variant’s initial contract includes five systems. The final mine plan will have as many as 30 chutes distributed underground – and up to 40 surface and underground haulage trucks for loading.
“We tested the first system onsite here in Canada,” Meloche said. “We fully assembled the system and ran it for a month. The customer was very pleased with the results they saw at our facility.”
The initial system has shipped to Mongolia and is awaiting underground installation.
In addition to enhancing operator safety, the ore handling system is designed to optimize mine throughput. When installed, each chute is expected to achieve a maximum instantaneous flow rate of 10,000 tonnes per hour (tph). Variant anticipates the system will enable significantly better traffic control and equipment utilization than other systems on the market.
“Overall, mining companies are most concerned about safety – and productivity,” said Meloche. “Our safety-rated SIL 3 system is designed to improve both.”
This truck loading control system is currently patent pending.