Hawk Measurement Praetorian Fiber Optic Sensing Stress Detection System for Tailings Dams Monitoring

Tailings Dams are massive structures used all over for the bulk storage of mineral processing wastes. These earthen structures can measure tens of kilometers in length and width and be hundreds of meters tall. In terms of total volume tailings dams are the largest manmade structures in existence. However, over the last 20 years the rate of tailings dams failing has doubled. Failures of tailings dams are perhaps the worst possible case scenario for any mineral extraction operation. Events causing loss of life in the hundreds or even thousands, Environmental fines reaching billions of dollars and the loss of facility infrastructure and production are a confronting prospect. HAWK has developed a solution to prevent tailings dams failure.

Principle of Operation:

HAWK’s Praetorian Geological Stress Detection System utilizes fiber optic sensing technology for the real time monitoring of field strain within earthen structures. This revolutionary technology uses fiber optic cables that are then inserted into the structure through drilled boreholes. These cables monitor field strain and deflection caused by dam loading and report both the borehole position and depth where the strain or deflection is occurring within the retaining wall structure. Sensitivities achievable with the Praetorian Geological Stress Detection System means that potential issues with ground shift can be detected and intercepted well in advance of visually symptoms of structural issues.

How does it work?

Distributed Acoustic Sensing (DAS) continuously monitors Vibration, Sound and Acoustic Energy along the fiber using a process called Rayleigh Backscatter along the entire length of an optical fiber. Using a “time of flight” calculation on the laser pulse the position of any incoming signal can be determined to within a meter on up to 80 kilometres (50 miles) of fiber.

Distributed Temperature Sensing (DTS) and Distributed Strain Sensing (DSS) work in a similar way, but use a looped fiber within the sensing cable to detect both Temperature and Strain. The laser is sent down both sides of this loop and the interference pattern allows for Brillouin Backscattering to be measured revealing changes to Strain and Temperature within the fiber.

Praetorian has a built-in Field Programmable Gate Array (FPGA) which quickly records, processes and analyses the data collected by the system and detects and reports signals generated by problematic events within the environment.

Features:

What does Praetorian tell me?

Praetorian has a built in Human Machine Interface (HMI) and can be operated directly or connected to existing Control Systems (such as SCADA) via a digital communications protocol (Typically TCP/IP) and report:

• The location of the alarm
• The classification of the alarm
• The alarms longitude and latitude
• The intensity of the alarm
• A time and date stamp of the alarm
• And other detected conditions depending on the specific application