Fiber Optic Sensors for Mine Hazard Detection

The two Key words are Time of Flight and Rayleigh Backscattering,

i. Backscattering is the return light from minute imperfections in the fibre, as physical changes such as temperature, strain and vibration act of the fibre the spectrum of this return light is altered. Rayleigh Backscattering is the part of this spectrum that responds to vibration which allows vibration in the field to be taken out of the return light.

ii. Time of Flight is like a sonar, laser or radar, in that the time the pulse is traveling relates to a distance, in Fibre optic sensing this is a not just taken at the reflection point but for every bit of the fibre the pulse travels though.

With good access and a properly sized team installation is accomplished within a few days. Sites typically install these systems as part of three or six monthly shutdowns.

The system utilises a Priority Level system similar to existing traffic light or colour code systems indicating severity from Priority 1: (Imminent failure highly likely) to Priority 4: (Low Level fault). This priority is given alongside frame number and belt side indication, i.e. “Priority 2 failure on frame 1145, northern side”.

Field experience has shown that a skilled operator is able to detect Priority 1 and 2 faults with a high probability of detection but are unable to reliably detect Priority 3 or 4 faults. The effect of this is that a failure detected by Praetorian is detected days or weeks ahead of any possible human detection.

This will vary depending on the specific hourly valuation of the asset being monitored, its size, specification and configuration. As an example, a previous client had calculated their ROI on monitoring a major overland belt as being only nine days!

a. This is customer dependant however the most popular choice is a daily report that can be processed to arrive in your inbox. This report is again customisable, but the typical choices include a “hit list” of idlers in indicating the number, position, time stamps and individual status of idlers of concern as well as list of idlers that have gotten worse since the last report (indicating rapid degradation) or idlers that have cleared (indicating a replacement has occurred).

b. The system can also be integrated with DCS or SCADA systems through Modbus TCP/IP and can even be integrated into machine learning with OPC tags outputs. 

c. Hawk also offers a self-hosted Geographical Information System (GIS) Graphical User Interface (GUI) that allows for easy alarm tracking, managing and history management as well as trending and the elegant display of idler data suitable for all levels of an organisation from operator to manager. 

The process varies, however typically it goes as follows:

i. We come to the site to measure up your belt(s)

ii. We prepare an installation instruction manual that you can share with your preferred contractor (your fibre communication contractors are generally your best starting point)

iii. We manufacture the parts to fit your belt and send them to you with all of the cable, casing and optical gear required to complete the project.

iv. We help by supervising the installation process as the contractor gets started.

v. After installation we come out and commission the system and provide ongoing support as the system matures and your operation works out the best way to use its output. 

In conveyors, 10km. Ranges are longer in other applications, however.

Yes, as many as you like up to 10km in length, however the distance between conveyors is included in that 10km. So, if you have two 500m conveyors that are 5km apart that would use 6km of the available length.

On both sides of the conveyor on the stringer, it can be attached to any surface of the stringer so long as there is a free run along that stringer.

In conveyors that don’t have a stringer there are several solutions available and it will be down to the unique set up of the belt which ones are used. 

We have metal bridges that span the gap protecting the fibre along its length.

a. We provide our system with the Patented Hawk Fibre Casing (HFC) System which encapsulates the fibre within a metal case that provides better contact with the structure, it also offers excellent mechanical protection against all but the most catastrophic conveyor incidents.

b. It can be repaired by any fibre contractor by adding in an extra piece of cable (around 20m) and attaching it to either side of the break. A quick remote recalibration is undertaken by us.

Yes, we encourage it in fact! We have specially made systems that are shipped all over the world specifically for technology trials.