In March 2014, three mineralised samples were sent to ALS Metallurgy, Tasmania for preliminary metallurgical assessments, to determine the mineralogical and flotation characteristics of low grade (Cu) Massive Sulphide, high grade (Cu) Massive Sulphide, and high grade (Cu) Stringer Sulphide; Stringer and Massive Sulphide being the two dominant styles of mineralisation identified at Mallee Bull to date.
- Preliminary assessments of the low grade Massive Sulphide demonstrated a strong chalcopyrite-pyrite association to fine size. Flotation results reflected the mineralogical assessment, with a finer grind required and a low grade rougher concentrate produced; however the upgrade ratios to rougher concentrate were encouraging, with test work producing the basis for assessment with the higher grade sample.
- The higher grade Massive Sulphide demonstrated a similar upgrade ratio to the low grade sample, with a resultant rougher concentrate of 7.3% Cu at 92% recovery achieved. This concentrate responded well to regrind and cleaning, yielding a 24.6% Cu grade concentrate at an overall recovery of 85.3%.
- The Stringer Sulphide showed more moderate chalcopyrite/pyrite associations and coarse grain sizing, with good liberation commencing at ~100µm. The flotation response was also significantly better with over 95.4% Cu recovery to a 23.3% Cu grade concentrate.