Tests were performed in the GIW Hydraulic Laboratory on a milled copper slag tailings slurry in pipe loops with 75 and 100 mm diameter loss sections. Volumetric concentrations of 1 to 14% were tested in the 100 mm loop, and the initial results, derived using magnetic flow meter measurements, showed pressure losses approximately equal to that of water. Chemical Testing of the solid particles was performed, and they were found to be made up of 56% magnetite by weight. Magnetite has been found in the past (Sonar Trac paper) to effect magnetic flow meter measurements, which was the primary method being used in this test program. Secondary measurements using a Sonar Trac instrument indicated, in contrast, the more common and expected equivalent fluid behavior in the 4” loop at the lower concentrations, where the losses, when expressed in height of slurry, now landed on top of the carrier liquid curve, which was found to be equal to that of water. A comparison between the measurements from the magnetic flow meter, and those from the sonar trac, showed a linear dependency between the flow rate ratio (between the magnetic flow meter measurement and the sonar trac measurement) and the solids concentration. These tests illustrate the importance of having knowledge of the makeup of the solid particles in a slurry, and the utility of acoustic based flow rate measurement methods in cases where magnetite (or other solids particles with magnetic properties) particles are present within the slurry.