Challenges & Improvements in Milling at Omai Gold Mines

January 21st, 2002

The paper illustrates continuous improvements Omai mine has undergone since its inception in 1993 as a 12,000 mtpd hard and soft rock SABC mill. Operations like Omai that have high tonnage and low-grade are forced to pursue options that allow them to maintain profitability despite today's depressed commodity prices.

To achieve this end, increases to throughput, equipment availability and gold recovery had to be considered. To satisfy these objectives, major changes were made to the mill, including an additional circuit similar to the original SABC configuration. Both the original mill, and the expansion, features similar SABC grinding circuits, however they both have separate gravity circuits. The initial gravity circuit featured Reichert cones and spirals fed by screened cyclone underflow bleeds. However, in an effort to improve gold recovery, the metallurgy staff at Omai decided to evaluate the effectiveness of the Knelson concentrator in replacing the spirals, the rougher table and part of the Reichert cones. After a brief trial period it was clear that the Knelson offered man advantages to the existing circuit, including higher recovery and reduced labour. The second gravity circuit has now been changed in the same way as the first gravity.

The Knelson Concentrator at Omai Gold Mine…

• has improved overall gravity recovery to over 40%
• provides very high availability, in excess of 99%
• has reduced labour costs compared to pre-Knelson installation
• has led to a similar Knelson-based system to be installed on the "B" gravity circuit

Download the full report here.

Challenges Improvements in Milling at Omai 374kb| 13 page Acrobat Info Sheet

source: "Challenges and Improvements in Milling at Omai Gold Mines" (Presented at CMP '99)