Agnico Eagle was founded in 1957 and is today the Kittilä mine in northern Finland, the largest primary gold producer in Europe. The mine extracts and processes about 4000 tonnes of ore per day, which results in the production of approximately 6000 kg of gold per year.
Customer challenge
The ore at the Kittilä mine goes through a treatment process of grinding, flotation, pressure oxidation and treatment in carbonin-leach circuits. A pressure oxidation circuit (autoclave) is required because of the ore’s refractory nature. Gold from the leach circuit is stripped from the carbon and then recovered from solution using electrowinning.
The primary chemical used in the separation process is cyanide, which due to its highly toxic nature places strict reliability and accuracy demands on pH measurements. An inaccurate or incorrect reading could result in a potentially hazardous situation. At the very least, such an occurrence would result in difficulties, delays and higher costs.
Agnico Eagle was not fully satisfied with the functionality and reliability of its existing instruments at the time. Inaccuracies in pH measurements resulted in diminished safety and process efficiency. In addition, the calibration of instruments was taking up a considerable amount of time and resources. Therefore, the company wanted to boost process control with measurements and, at the same time, improve the maintenance of the measurement devices.
The Endress+Hauser solution
Agnico Eagle carried out an extensive year-long field trial with various manufacturers. Endress+Hauser came up on top, largely thanks to its high performance instruments, its know-how as well as the friendly and competent service that accompanies the products. The process in the Kittilä mine is not an easy one for measurement and analysis devices, and there are no simple solutions, but technical issues were solved through close cooperation between the Agnico Eagle and Endress+Hauser teams.
The Memosens and Liquiline platforms are used as a solution for the challenges concerning pH measurements. The Liquiline digital transmitters and the Memosens sensors are the perfect set-up for demanding liquid analysis. The Memosens sensors perform reliable measurements even in extreme conditions and in demanding applications. The non-contact digital signal between the sensor and the transmitter is very reliable and is not disturbed by any external factors, such as moisture. Calibration can be performed outside of harsh field conditions, and furthermore, the devices facilitate preventive maintenance.
Correct calibration is the basis for reliable measurements and analysis. Thanks to the Memosens technology calibration is easier than ever before, and no longer needs to be carried out in difficult and hazardous field conditions.
A perfect complement is the calibration diagnostics and laboratory measurement software Memobase Plus. It allows for a connection between a computer and the Memosens sensor via USB port, giving virtually instantaneous access to the sensor condition and diagnostics information.
For grab sample measurements, Agnico Eagle decided to use Liquiline To Go. The handheld allows the same sensor types to be used for grab sample measurement as in the process. This eliminates deviations resulting from the use of different sensor technologies.
The cleaning of devices positioned outdoors was difficult, time consuming and inconvenient, especially during the winter months. The automatic cleaning feature of the Endress+Hauser instruments provides Agnico Eagle measurable improvements in terms of both efficiency and staff satisfaction.
The results
The time spent on calibrations and field repairs was reduced from 2200 to approximately 240 labour hours per year – a reduction of 90%.
Maintenance activities no longer have to be carried out under difficult conditions in the field so that working safety and convenience have been improved.
Using the same measuring technology for manual and inline measurements led to complete data consistency and thus, to more confidence in the measuring results.
The consumption of chemicals was reduced by up to 50% because of the more accurate pH measurements. The optimised dosing saves money and increases process as well as occupational safety.
For more information contact Jan Swart, Endress+Hauser, +27 (0)11 262 8000, [email protected], www.za.endress.com
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