Gold Mining – Cyanide
Masbate, Philippines, 2013.
A large gold mine situated in the Philippines needed to monitor cyanide levels at below 0.2ppm. They were using an expensive automated WAD analyser that was incapable of reliably measuring below 3ppm. The target rate for discharge was less than 0.1ppm with the upper end limit being set at 0.2ppm as the maximum environmental allowance.
A Turtle Tough Cyanide Analyser was installed in the mine sites water treatment plant detoxification area.
The mine site had extremely high flow rates, so a 30mm off-take line was utilised with a flow rate slowed to approximately 2L/m. This provided optimal conditions for stable measurement at such low cyanide levels. The optimum pH range for such a low level detection is between pH 9.5 and 10.0. The raw water feed on-site had an ideal pH of 9.8, so no dosing was required.
Utilising the standard 4-20ma analogue output into their SCADA system the mine site are able to continuously monitor their discharge water. Due to the critical nature of this environmental monitoring the site chose to install a second system for double redundancy. Site personnel are extremely happy with the simplicity and performance of the system. Results are stable and coincide with all lab results. The cost of this monitoring solution was less than a third of competitive systems.