Acid rock drainage

The ALS Vancouver laboratory can conduct the following analyses:

Acid Base Accounting

Acid Base Accounting procedures are used as a screening process to categorise materials into potentially acid generating and potentially non-acid generating. For material where the potential for acid generation is uncertain, humidity cell testing is performed to attempt to define acid generation characteristics.

Humidity Cell Testing

Humidity cell testing (also referred to as Kinetic Cell testing) is designed to mimic weathering of samples in a controlled fashion at the bench scale. The test determines the rate of acid generation and the variation over time in leachate water quality. Samples are subjected to weekly cycles that alternate between the circulation of dry air and moist air over the samples to simulate precipitation cycles. The weekly leachates produced during the humidity cell procedure are typically analysed for a number of parameters. Humidity cell design can be customised to meet a variety of client or site specific needs. All ALS humidity cell sampling and laboratory analyses are performed based on recognised standards such as the American Society for Testing and Materials (ASTM D5744-96) and Guidelines and Recommended Methods for the Prediction of Metal Leaching and Acid Rock Drainage at Minesites.

The typical ALS humidity cell weekly analysis package includes the following analyses:

• pH
• Conductivity
• Acidity
• Alkalinity
• Anions (Cl, F, SO4, NO2 & NO3)
• Dissolved Metals (ICPMS Scan & Hg)
• Additional analyses that can be added as required include: Ammonia, Total Phosphate, Oxidation Reduction Potential

Other analyses available include:

• Metals analyses
• Shakeflask extraction
• Column leach studies