The process mineralogy of gold at the Tuzon deposit, Liberia.

摘要

The Tuzon deposit is an orogenic gold deposit hosted by orthopyroxene gneiss. Structural investigations of the mineralization confirm that the gold is pre-orogenic hosted within a highly deformed Theological discontinuity and currently developed as a recumbent fold. This pre-orogenic origin for the gold mineralization is in contrast to other Birimian Supergroup gold deposits which are predominantly syn to post-orogenic in nature. The only other recorded pre-orogenic gold deposit is from sedimentary turbidite deposit possibly making the Tuzon deposit unique amongst Birmian gold deposits. Based on investigations of the gold mineralogy and textural associations it is possible to deduce a paragenetic history of the mineralisation along with processing implications. Initial work suggested complex processing requirements with a majority of fine-grained gold (<5 urn) and the presence of a small percentage of gold-bearing minerals as refractory maldonite. However, detailed assessment of the mineralisation showed that ~85% of gold grains lie within alteration planes or along grain boundaries. With a suitably fine grind, fracturing may occur along these boundaries exposing part of a gold grain. This is important for the cyanidation process as liberation is only needed to the point where part of the gold particle is exposed. Initial testwork confirms the high potential gold recovery. The results show that accurate assessment of processing potential depends upon a detailed understanding of ore textural development.