Knelson Gravity Solutions

Gwalia Circuit Shines at Gwalia Mine

St. Barbara Limited is an Australian gold producer and mineral explorer with key assests at Southern Cross and Leonora, both of which are located in Western Australia. The Leonora operations comprise of the 1.2 Mtpa Gwalia processing plant and associated mines. Gwalia commenced gold production with the first gold pour completed in October 2008.

"The Gravity Circuit has performed beyond expectations when comparing its current performance against the preliminary test work conducted on the Gwalia underground ore."
John Zimmerman; Gwalia Plant Metallurgist

The original Gwalia Mine has a long and storied history. This is the site where an American Geologist named Herbert Hoover made his fortune prior to returning to the US, eventually becoming US President from 1929-1933.

The Gravity Circuit installed at Gwalia was purchased as a package from Knelson's Australian affiliate Consep Pty Ltd. Consep supplied a 1.2 x 2.4m Sizetec Screen,
KC-XD30 Knelson Concentrator and a CS1000 Consep Acacia with Electrowinning. The complete Gwalia gravity circuit is controlled by a PLC control system designed and supplied by Consep.

According to Gwalia's Plant Metallurgist, John Zimmerman, "St. Barbara Limited's Gwalia mill typically operates at 180t/hr, treating an ore blend of higher grade underground material and low grade open pit ore. The mill feed grade varies between 2-10g/t depending on the ore blend available."

"Due to this variability in feed grade, the performance of the Gravity Circuit also varies in respect to the percentage of gravity recoverable gold extracted. On average we have observed 37.1% of total gold reporting to the mill recovered through the Acacia unit year to date. The overall plant performance for the same period had average recoveries of 93.6%."

"The Gravity Circuit has performed beyond expectations when comparing its current performance against the preliminary test work conducted on the Gwalia underground ore. The test work showed expected gravity recoverable gold of 34.5%, whereas the current performance achieved by the gravity circuit is 37.1%."

Both of St. Barbara's operating plants, being the Marvel Loch Plant (Southern Cross Operations) and Gwalia (Leonora Operations) operate Knelson Concentrators.