New suspended solids monitoring system achieves major savings in maintenance costs for Alcan

Citation

(2001), "New suspended solids monitoring system achieves major savings in maintenance costs for Alcan", Sensor Review, Vol. 21 No. 3. https://doi.org/10.1108/sr.2001.08721caf.006

New suspended solids monitoring system achieves major savings in maintenance costs for Alcan

New suspended solids monitoring system achieves major savings in maintenance costs for AlcanKeywords: Flow, Measurement, Sensors

World number two producer of aluminium, Alcan has made significant improvements to its bauxite extraction process, through use of the MSM400 sludge density monitor from Solartron Mobrey (Plate 7). Field trials of the ultrasonic sludge sensor by Alcan in Canada have been so successful that the company is recommending the technology to all its facilities world-wide.

Alcan's alumina refinery (Vaudreuil Works at Saguenay Lac-St-Jean, Quebec) processes more than 2.5m tonnes of bauxite per annum. Bauxite mud is washed to remove the alumina liquor, in a continuous extraction process which relies on suspended solids sensors to detect the sludge blanket.

Plate 7 World number two producer of aluminium, Alcan, has made sigificant improvements to its bauxite extraction process, through use of the MSM400 sludge density monitor from Solartron Mobrey

The mud circuit area, as it is known, is a very aggressive environment. The bauxite mud is highly caustic and the process temperature is 107°C. In the past, suspended solids sensors had to be replaced often, to maintain reliability of the control signal. With an expected sensor life of less than three months, and sometimes only a few days, the sludge detection system was proving expensive to maintain.

Solartron Mobrey, and its Canadian distributor BEP-Bestobell, worked closely with Alcan to develop a suspended solids monitoring system that would deliver reliable sludge density control in the harsh conditions of the alumina refinery. The result was Solartron Mobrey's MSM400 system. Use of the system has increased the average sensor life by more than 30 per cent, reducing Alcan's annual maintenance and equipment costs by thousands of dollars.

The MSM400 consists of a microprocessor-based control unit and a pair of ultrasonic sensors. Density is measured by monitoring the attenuation in an ultrasonic signal transmitted through the sludge.

Denis Turcotte, Maintenance Technical Group Manager for Alcan at Vandreuil, explains:

We were able to use the attenuation factor to calibrate the control unit with more accuracy than we had ever been able to do before. Solartron Mobrey's sensor assembly is designed for use at high temperatures, in the caustic environment of bauxite mud. As a result, sensor lifetime has increased by more than 30 per cent, reliability of the control signal is increased, and maintenance costs have been reduced.

MSM400 systems are now installed at Vandreuil, and Alcan is actively recommending use of the technology to its other processing sites around the world. The system is also integrated into the mud circuit equipment marketed by Alcan as part of the alumina extraction technology solutions it sells worl-dwide.

The MSM400 has a range of built-in display, control, alarm and communications options. It is easily programmable to suit local conditions and comes complete with a range of factory-set calibrations for speedy set-up.

For further information contact: Peta Glenister. Tel: +44 (0)1753 756600; Fax: +44 (0)1753 787109; E-mail: peta@mobrey.com