Mexican mine replaces nuclear gauge with slurry density meter technology to monitor and improve tailings thickener efficiency.
The Rhosonics slurry density meter (SDM) has taken up the task of improving the operational efficiency of Minera Mexicana ‘La Ciénega’, a Fresnillo mine located in Durango, Mexico. The mine, which has been operating since 1992, engages in exploration, mining, and processing of gold, silver and other minerals.
The purpose of testing the SDM was to evaluate an alternative to the existing nuclear density meter for monitoring density in the tailings thickener underflow. This measuring point is crucial since they need to track how much slurry is being transferred to tailings at all times. Additionally, the company aimed to optimise the thickener underflow to improve operational efficiency.
The ideal solution
The SDM was an ideal choice due to its reliable and real-time measurement results. A 30-day trial was conducted to evaluate the use of a nuclear density gauge and the Rhosonics density meter. The SDM proved to be a better option than the existing radiation-based technology as it coped well with the measuring task and process challenges. The SDM uses ultrasonic technology, which eliminates the need for government licenses and the cost of employing and training specialist employees for maintenance and calibration tasks.
According to the client, the SDM was able to successfully measure density, reliably and accurately, which enabled them to efficiently monitor and control the slurry transfer process from the thickener underflow. Minera Mexicana ‘La Ciénega’ has a production capacity of 4,000 tons per day, making it essential to have reliable and efficient processes in place. With the SDM, the mine now operates with increased efficiency and productivity.
Another happy customer
The SDM is also being used at the Meadowbank complex in Northern Canada, where ore from the Amaruq deposit is comminuted and separated to recover gold from the gangue (tailings). Density meters are needed for control purposes in the grinding and separation processes. These instruments help the operators to monitor the efficiency and fully utilise the production capacity. The outputs of density meters and flow meters are combined to calculate the production output. Agnico Eagle chose to replace conventional nuclear sources (part of the initial plant design in 2008) with the SDM.
The SDM can provide real-time readings on the densities of the slurry flowing in the regrind circuit. The measurements are reliable, stable and friendly to the work environment. Since the device is non-nuclear, calibration is made easy and RSO training for radiation safety is not needed. Agnico chose to use a Rhosonics RCU device for convenient (remote) control of the SDM unit installed in the cyclone feed.
Agnico Eagle is currently using the SDMs at two different locations in their regrind circuit. Some of the results are: ability to directly detect changing process conditions; and reaching target density and production output.
Process operators use the density value to achieve stability in the circuit and recover the maximum ounces of gold. Real-time density control helps them to operate at a proper density level and prevents piping to block. Using a flow meter, they also calculate the production output (mass flow).
The device saves costs on inspections, procedures and licenses related to radiation safety. According to the site electricians, the SDM was easy to install and requires little maintenance.
The density meters save a lot of time spent on manual sampling using a Marcy scale. The number of manual samples is reduced drastically. Without on-line assessment, a sample would be taken three or four times per shift. One sample takes about five minutes.
The successful implementation of the SDM at Minera Mexicana ‘La Ciénega’ and the Meadowbank complex sets a precedent for other mining companies to follow, improving operational efficiency using an eco-friendly technology and driving the mining industry forward.