Blasting is often used in mining as an effective way to clear large areas. Bores are drilled and explosives are carefully placed to ensure a safe and predictable blast. When positioning explosives the temperature in the bore is a critical factor to take into account. A higher temperature can make the explosive charge more volatile causing it to detonate too soon.
I designed and prototyped a temperature sensor for an Australian mining company. The temperature sensor was designed to be on the end of a long cable reel and transmit readings using a data bus to a handheld unit. I implemented an opposing dual infrared temperature sensor to accurately read the temperature of the earth and rock on both sides of the drilled bore as the sensor was reeled deeper down. This data, combined with reel position information, maps temperature and depth giving the explosives technician the information required to precisely set and position blasting charges.
- Accurate and instantaneous temperature measurements.
- Calibration procedure and test rig.
- Low latency and reliable data bus over long distances.
- Data and power in low circumference but rugged cable.
- Physical dimensions very compact (70 x 20 mm). High density surface mount technology used.
The following are some photos of the prototypes showing the populated PCB, and IR sensors. The IR sensors are snap-off boards for manufacturing efficiency – the entire electronics can be processed as a single unit, and broken apart for final assembly.