Renison is the largest of three major Skarn, carbonate replacement, pyrrhotite-cassiterite deposits within western Tasmania. The Renison Mine area is situated in the Dundas Trough, a province underlain by a thick sequence of Neoproterozoic Cambrian siliciclastic and volcaniclastic rocks. At Renison there are three shallow-dipping dolomite horizons which host replacement mineralisation.

Mount Bischoff is the second of three major Skarn, carbonate replacement, pyrrhotite cassiterite deposits within western Tasmania. The Mount Bischoff Mine area is situated within the Dundas Trough, a province underlain by a thick sequence of Neoproterozoic- Cambrian siliciclastic and volcaniclastic rocks. At Mount Bischoff folded and faulted shallow dipping dolomite horizons host replacement mineralisation with fluid interpreted to be sourced from the forceful emplacement of a granite ridge and associated porphyry intrusions associated with the Devonian Meredith Granite, which resulted in the complex brittle / ductile deformation of the host rocks. Lithologies outside the current mining area are almost exclusively metamorphosed siltstones. Major porphyry dykes and faults such as the Giblin and Queen provided the major focus for ascending hydrothermal fluids from a buried ridge of the Meredith Granite. Mineralisation has resulted in tin-rich sulphide replacement in the dolomite lodes, greisen and sulphide lodes in the porphyry and fault / vein lodes in the major faults. All lodes contain tin as cassiterite within sulphide mineralisation with some coarse cassiterite as veins throughout the lodes.

The Area 5 orebody has a number of characteristics differentiating it from the remainder of the Renison orebody:
• Greater depth.
• Occurs in a wider continuous zone.
• Generally has a higher talc content.
• Moderately, rather than steeply, dipping.
• Continuous across several geological domains.
• Significantly higher tin content than most other mine areas.
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Renison mine production stabilises at approximately 930,000 tonnes per annum (tpa) after an initial ramp-up from approximately 900,000 tpa, with production rate limited by stope production scheduling and underground asset capacity. Over the 10 year mine life, Area 5 contributes approximately 40% of total contained tin in mine production.

Area 5 subset Ore Reserve of 3.30 Mt at 1.87% Sn for 61,900 tonnes of contained tin, including 2.2 Mt at 2.11% Sn for 46,400 tonnes of contained tin from a distinct high-grade portion of the Mineral Resource.

Area 5 Mine Design
Renison staff selected mine design is based on a stope size of approximately 15 m x 15 m, and vertical stope height of 40 m. Hangingwall exposures have been minimised by creating vertical walls across the orebody (where required).

Long hole stoping with engineered backfill was selected to extract the wide orebody in Area 5. Mining will be in a bottom up sequence and a single continuous mining front from the north.

Area 5 Ventilation
The Area 5 Study has recommended the development of the No.14 Ventilation System as a ventilation exhaust system dedicated to Area 5. It comprises a series of three raise bored shafts with a planned diameter of 5.0 m from surface to 1020 mRL (approximately 1.2km depth) with connecting drives. A 55 m surface pre-sink is required to reach rock suitable for raise boring. A twin exhaust fan will be installed on the surface with ventilation control devices (doors, barricades & regulators) installed underground.

The construction of the new exhaust system will commence in Q4 2020 following completion of engineering and tendering, and is scheduled for completion in Q2 2022.

Area 5 Backfill Design
Suitable backfill material is integral to the implementation of a successful extraction sequence for Area 5, with the major aim to allow the recovery of as much as possible of the wide, high grade zones in the orebody. Backfill material testing and recommendations were conducted by Outotec Oyj. Backfill materials used for Area 5 bulk stopes will satisfy the following requirements:
• Sufficient strength to ensure the stability of large vertical faces (exposures) when stopes adjacent to the backfill are being mined.
• Sufficient flow to ensure the stope voids are tight filled.
• Engineered fill required to meet the backfill requirements in the Area 5 bulk zone

The backfill required in Area 5 bulk area will consist of the following components:
• Cemented fills to ensure the stability of any exposures when stope adjacent to the backfill are being mined.
• Engineered fills such as Cemented Aggregate Fill, Cement Hydraulic Fill and Paste Fill, can meet the strength demand that is required for the lower 20 m section of each stope void.
• Slurry type fill is required to ensure the stope void is tight filled.
• Cemented Rock Fill can be used in the bottom 20 m of the stope void representing approximately 35% of the Area 5 stope void over the LOM Plan.

Further evaluation of the backfill system and surface plant requirements is be undertaken during FY21 with commencement of construction from July 2021.

The Renison mine produces a tin concentrate of grade varying between 50-60% Sn with internal process designed to reduce penalty metals such as iron, sulphur, tungsten and copper. The metallurgical process is complex and applies several stages of gravity-type concentration as well as sulphide and oxide flotation, regrinding and acid leach methods. The metallurgical recovery is estimated from plant feed grades and is based on historical plant performance with modifying factors for different ore sources. Metallurgical recoveries on the various ore types and grades were considered as part of the cut-off grade analysis.
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The throughput capacity of the Renison processing plant is approximately 1 Mtpa. The ore sorter provides flexibility and additional throughput capacity.

The ongoing Metallurgical Improvement Program is expected to deliver significant ongoing ........