While looking further into the 2021 Resource Estimate, it seems that most of the recoveries can be achieved with primary grind size under 151 microns.  Not quite sure the Eriez Technology could add significant value, as it seems to address an issue for bigger particules.

"At an average primary grind size of 80% passing 151 µm, G&T test work data shows that on average, 86.2% of the copper was recovered from the head sample containing approximately 0.37% Cu. The other associated metal recoveries were 73.3% for gold, 55.7% for silver, and 71.9% for molybdenum. The average sample feed grades were approximately 0.27 g/t Au, 2.7 g/t Ag, and 0.019% Mo. The concentrate produced contained 30.9% Cu. The average data from G&T and PRA show that at the primary grind size of 80% passing 146 µm, 86.7% of the copper reported to the copper concentrate at a grade of 29.9% Cu. The gold, silver, and molybdenum recoveries to the concentrate were 74.7%, 56.9%, and 73.7%, respectively. Apart from lower-grade concentrates produced by PRA, the test results from the two laboratories were very comparable."

I'm still wondering why higher metal recoveries where not used in the PEA.  Based on all the historical information available, the below was in the summary section of the 2021 RE.

"According to the metallurgical performance projections conducted in the 2013 study, the metal recoveries for the Schaft Creek deposit are projected to average 86.6% for copper, 73.0% for gold, 58.8% for molybdenum, and 48.3% for silver."

MoneyK