Bulawayo Mining Company owns How Mine which is Metallon's flagship low cost, mining operation.
How Mine is located in Matebeleland-South province, about 30 kilometres southeast of Bulawayo in southern Zimbabwe.
How Mine is situated in the Bulawayo greenstone belt and exploits several individual mineralised pods situated within a sigmoidal structure which dips at 70° to 80° west. The pods are broadly cigar-shaped bodies comprising zones of enhanced hydrothermal alteration and gold mineralisation that plunge steeply. Mineralisation within the orebodies consists predominantly of pyrite (>90%) with minor chalcopyrite and pyrrhotite and is associated with silicification and carbonation. Gold is found in contact with the sulphides, often in fractures, although there is also some free gold. Some silver occurs with the gold, increasing from 4% to 8% of gold as mining progresses down-dip.
Mining and processing
How Mine has been in operation since 1942 and has produced over 1.1 million ounces of gold to date. It comprises a single underground operation, where ore is processed at a central processing facility, using a combination of conventional milling and a carbon-in-leach process.
The mine currently milling capacity is 33ktpm of ore sourced from underground operations and surface dumps, with hoisting capacity of 36ktpm. The average mined grade is approximately 5g/t. Production in 2016 was 50,191 ounces, with C1 costs of US$520 per ounce and AISC of US$660 per ounce. This is one of the lowest cost mines in Africa.
- Current resource: 1.0 million ounces of gold (Mineral Reserve Statement Dec 2016)
- Life-of-mine: 13 years
Ongoing exploration is related to the down-dip continuation of the current orebodies. The footwall geophysical anomaly is an interesting target for underground exploration drilling.
Past trench and core drilling results at both Glen High and particularly Glen May are worthy follow-up targets within the How Mine lease boundary.
A surface diamond drilling exploration program is in progress at Three Castles Prospect located about 5km southeast of How Mine, within the Mining Lease. The objective of the exploration program is to delineate near surface resources amenable to open pit mining to supplement underground production.
The mine has commenced the deepening of the 16N7 Shaft in order to increase ore supply. The shaft deepening from 28L to 34L is to access ore below 28 Level which will increase future production. Commissioning of the deepened shaft is expected in 2018.
How Mine continues to seek opportunities for acquisition of properties for exploration. Exploration in the acquired claims will initially target near surface resources amenable to open pit mining. The objective is to open satellite mines that will supplement underground production at How Mine.