Automation IIoT Reliability Sensors

Breaking Mining Data Silos

EP Editorial Staff | March 12, 2020

Wireless technology, connecting even legacy PLCs, can play a large role in improving efficiency and safety. Note: For security reasons, photo is not of the operation described in article.

Pressure to enhance efficiency and meet production targets drives improved operational visibility through data gathering.

Mining processes are often managed by programmable logic controllers (PLC). Most legacy PLCs, designed in the early 2000s, cannot transfer data beyond the factory floor for diagnostics and analytics. They lack built-in wireless connectivity and come with a plethora of proprietary, vendor-specific serial protocols designed to serve closed-loop automation tasks. Any redesign or modification of PLCs to integrate add-on IoT connectivity requires costly production halts and is conducive to equipment failures. Newer PLCs provide onboard web servers for data acquisition, but again, complex configurations are required to connect these servers with an IIoT system.

To avoid invasive reprogramming, a common approach is to feed PLC data directly into an internet-connected gateway using native protocols on the PLC. The gateway then transfers this data to an IIoT cloud platform. This architecture is problematic in an open-pit mine where Ethernet-wiring to the IoT gateway is highly constrained, if not impossible. The remote location and asymmetric topography typical at mine sites means that a cellular backhaul option is either unreliable or missing altogether.

Real-World Example

A Canadian-based gold-and-silver mining company is an example of how the PLC connectivity challenge plagues mining operations, specifically in the heap-leaching process. In gold mining, heap leaching is an extraction activity in which gold is separated from the ore through a sequence of chemical reactions that use cyanide. Controlling cyanide pH is critical, as decreased pH values cause the formation of lethal cyanide gas while magnifying cyanide consumption. Lime is used as the reagent for pH control.

At the company’s Nevada mine, lime storage, mixing, and dosing activities are controlled by a local PLC. The lime silo and the PLC are entirely disconnected from the administration building, located on the other side of a 300-ft.-high heap leach. Besides making Ethernet cabling impossible, the heap leach hinders effective implementation of conventional wireless solutions by blocking direct radio link.

The lack of connectivity left a visibility gap. Operators failed to obtain accurate information on actual lime dispensing rates, and the only way to know the current silo level was to drive to the site three to four times a day for manual data logging.

Connecting PLCs to battery-powered wireless tranceivers using a robust, long-range radio link could reduce hardware, installation, and management costs.

Plug-and-play IIoT

The challenge was to find a communication solution that could be easily and non-invasively retrofitted into the brownfield PLC and provide reliable data transmission over the heap leach to reach the administration building. The company turned to BehrTech (Behr Technologies, Toronto, and Majik Systems’ (Kitchener, Ontario, for a joint solution. The solution uses BehrTech’s MYTHINGS, a wireless connectivity platform using TS-UNB (MIOTY) low-power, wide-area-network (LPWAN) technology, and the Majik software suite for PLC data acquisition.

An integration gateway, running the software, connects with the brownfield PLC using onboard serial or Ethernet ports and derives critical data points. A MYTHINGS transceiver, connected with the integration gateway, transfers the data to a base station. Data is relayed to a backend-server of the user’s choice, on premises or in the cloud, providing flexibility and control in operational data storage and management.

Several factors sold the company on this solution. It’s plug-and-play and does not entail complex, error-prone hardware changes or PLC reprogramming. With ETSI-certified TS-UNB technology at its core, the MYTHINGS platform was expected to provide robust, long-range data transmission that works around a large physical obstruction. One-way data transfer, from the PLC to external systems, ensures the security of automation networks, as attempts to remotely control machines through reverse communication aren’t possible.

A pilot installation was conducted to test the solution at the Nevada site. Selected PLC tags, including silo level, scale total weight, and lime dosing counts/hour, were transmitted every 5 min. to a MYTHINGS base station. The station was located inside the administration building. Data was then forwarded to a central PLC that visualizes current mining processes and a cloud platform for predictive analytics.

Upon installation, the mining company could derive and transfer PLC data into its backend for visualization with no message errors observed. Having real-time information on the lime silo level at hand, refills were accurately planned to avoid production delays and over ordering. On-site inspections could be eliminated.

PLCs are used in almost, if not every, industry. Having legacy PLCs connected to battery-powered wireless transceivers from where data is transmitted using a robust, long-range radio link could reduce hardware, installation, and management costs. EP

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