SDMs at Agnico Eagle

Measuring Task

Slurry density measurement in two applications in the regrinding circuit.

Grinding mill feed density

  • Solids: 50 – 60 wt%
  • Average density: 1.500 g/l
  • Flow velocity: 1 – 3 m/s

Cyclone feed density

  • Solids: 20 – 25 wt%
  • Average density: 1.200 g/l
  • Flow velocity: 1 – 3 m/s

Challenge

  • Improve process control with real-time density data
  • A consistent cyclone feed (target density)
  • Stability in the feed density of the regrind mill
  • Use radiation-free and reliable density meters

Instrument used

Solution

The Rhosonics 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.

Results

Agnico Eagle is currently using the Rhosonics density meters for 18 months (since June 2019) at 2 different locations in their regrind circuit. Some of the results are:

  • Ability to directly detect changing process conditions
  • 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 – considering three shifts and four samples per shift, it would take about 60 minutes a day.

The density meters work well. We do a quick verification with Marcy once per week. If we need to adjust, we call the electrical department and they come. Density takes 5 minutes to take, but 3-4 times per shift x 5 minutes, that is a lot of time consuming. Having these instruments online is really efficient and operators love them

Eric Mercier, Metallurgist, Agnico Eagle

You can read the whole story about the success of Agnico Eagle Meadowbank in the case study. Click on the image below to download the case study.

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