TRITTON DEPOSIT
The Tritton deposit is a sulphide copper mineralised body located on ML1544 in central New South Wales (NSW), Australia. The deposit geology is best described as a structurally controlled sulphide deposit. Copper mineralisation, in the form of chalcopyrite is associated with a late-stage regional deformational event.

Regionally mineralisation is hosted within early to mid-Ordovician turbidite sediments, forming part of the Girilambone Group. The Tritton deposit is hosted within greenschist facies, deformed pelitic to psammitic sediments, and sparse zones of coarser sandstones.

Sulphide mineralisation within the Tritton tenement package has been classified as either a structurally controlled epigenetic sulphide system or a stratiform “Besshi style” volcanogenic massive sulphide (VMS) deposit. Recent geological investigations at both the Tritton and Murrawombie deposits have identified a sulphide mineralisation occurring late in the structural deformation events. There is decreasing support for the VMS model of deposit formation as we can better undertsnading of the deposits.

Sulphide mineralisation is dominated by massive, banded and stringer pyrite +/- chalcopyrite, with a relatively consistent massive pyrite – chalcopyrite unit along the hanging wall contact. Alteration assemblages adjacent to mineralisation are characterized by an ankerite/chlorite footwall and silica sericite hanging wall.

The host Girilambnone Group sediments are turbidite lithologies with a range from shale, siltstone, fine grained sandstone and occasional medium-coarse grained sandstones. Occasional mafic sills intrude the sediment package.

Several regional deformation events are evident in the region. Sulphides (pyrite and chalcopyrite) occur along sites of dilation associated with a later ductile deformational event. Sulphide mineralisation is dominated by massive, banded and stringer pyrite +/- chalcopyrite, with a relatively consistent massive pyrite – chalcopyrite unit along the hanging wall contact. Alteration assemblages adjacent to mineralisation are characterized by an ankerite/chlorite footwall and silica sericite hanging wall.

The main Tritton mineralised zone is tabular in nature with an overall down dip length of 1.9 kilometres with mineralisation still open at depth. Mineralisation begins at approximately 155m below surface (5,115mRL). The main body varies in thickness averaging 6-8m above the main “roll over” at 4,500mRL. Below the “roll over” the mineralised sulphide package thickens with true widths in the order of 15 to 30m to 4,300mRL. Below this the mineralised body dips at a shallower angle (25 ) and thickens to 70m thick down to the 3,970mRL. The mineralised system below 4,300mRL level is influenced by a NW-SE trending F4 fold corridor. Within the fold corridor the mineralised system becomes progressively deformed and is responsible for the geometry change (N-S trend to E-W trend) and increased thickness.

MURRAWOMBIE DEPOSIT
The Murrawombie deposit is a sulphide copper deposit located on ML1280 in central New South Wales (NSW), Australia. The deposit geology is best described as a structurally controlled sulphide deposit. Copper mineralisation, in the form of chalcopyrite is associated with a late-stage regional deformational event.

Copper mineralisation at the Murrawombie deposit is hosted within early to mid-Ordovician turbidite sediments, forming part of the Girilambone Group. Turbidite lithologies range from shale, siltstone, fine grained sandstone and occasional medium-coarse grained sandstones. Occasional mafic sills intrude the sediment package. Several regional deformation events are evident at the Murrawombie deposit. Sulphides (pyrite and chalcopyrite) occur along sites of dilation associated with a later ductile deformational event. Post mineralisation faulting is common in the form of north-south striking (mine grid) graphitic faults.

The Murrawombie deposit consists of several elongate sulphide envelopes orientated parallel to a pervasive S2 fabric which is interpreted as forming parallel to bedding. The elongate sulphide lodes are defined by a long down dip axis (+300m) and a shorter strike (100m to 150m) and thickness ( 30m). To date eleven sulphide lodes have been discovered at Murrawombie with the 102, 105 and 108 lodes the largest discovered to date. Sulphide mineralisation is dominated by pyrite and chalcopyrite, which varies from massive pyrite +/- chalcopyrite to erratic stringer pyrite/chalcopyrite veins. Sulphide mineralisation pinch and swells which is in part a result of bounding graphitic fault zones deforming the mineralised lenses. Post mineralisation faulting, in particular graphitic faults trend at an oblique angle (approximately 10°) to mineralisation. The graphitic faults constrain the northern strike extensions of the Murrawombie mineralised system.

The Murrawombie resource occurs as several discrete/stacked tabular lenses covering an area approximately 750m north–south and 900m east–west with mineralisation starting from near surface. Fresh mineralisation begins at approximately 140m below surface.

The tabular lenses have strike lengths ranging from 50m to 500m and down dip extents ranging from 90m to 500m with a total down plungeextent of approximately 1,000m. The lenses vary in true width from 2m to 3m, with an average true width between 5m to 10m.

Internal non mineralised zones of material between the mineralised lenses vary between sub 2m to +10m. The overall thickness of the mineralised package including the internal non-mineralised horizons varies between 2m to 60m. The current Murrawombie resource has been interpreted to a depth of approximately 700m below the current surface and is still open at depth. The current resource is not closed off along strike.

The mining method assumed in the Ore Reserve estimate varies with the deposit. At the Tritton deposit, the method is sub-level open stoping with cemented paste fill. At the Murrawombie deposit, the ore is extracted using underground bench stopes and small open stopes with cemented rockfill. Future mining of the shallow remnant portion of the Murrawombie deposit will be by open pit, as the final extraction stage. The yet to be developed Avoca Tank deposit project is planned to use up-hole benching with dry rock fill.

TRITTON DEPOSIT
The mining method used at Tritton mine is sublevel open stoping with paste backfill. Transverse or longitudinal stope orientation is used depending on the geometry of the ore lenses. Transverse stopes are designed where there is enough width. In the widest areas of the deposit several stopes will be mined across the strike in a grid pattern. Stopes will have between two and four wall exposures of cemented backfill, depending on their location in the extraction sequence.

Stopes are backfilled with cemented paste fill made from mill tailing. Use of paste fill provides support for the ground around mined out stopes, and permits a top down extraction sequence. The use of cemented paste backfill has allowed a high rate of conversion from Mineral Resource to Ore Reserves.

Stopes are mined between sub-levels separated by a standard 20m vertical distance. The sublevel interval is increased where possible to reduce mine development. Sublevel spacing has increased below the 4,165mRL sub level in response to changing geometry of the deposit. Above 4,165mRL the default standard 20m sublevel interval was used to maintain stable hanging wall exposures at the 35-degree dip of the ore body. Below 4,165mRL the ore body is thicker in the vertical dimension, allowing an increased sublevel spacing of up to 30m, without compromising hanging wall stability.

Individual stope height varies from 20m to 80m depending on the local geometry and predicted hanging wall stability. Average stope size is 60k tonne for the Proved Ore Reserve. The mineralisation is generally thicker in the region 4200mRL to 4030mRL, so larger, taller, and vertically aligned stopes have been designed in this area of the mine.

Mining extraction was traditionally sequenced as top downwards, using cemented paste backfill to provide side wall and hanging wall stability. Below 4,100mRL the sequence has changed to a modified bottom up extraction. A natural break in the ore body at 4,100mRL allows for a crown pillar with minimal ore loss. The stopes below this level commence at around 4,030mRL and are vertical. They will be mined in a single pass from bottom to the base of the crown or edge of the ore body.

MURRAWOMBIE DEPOSIT
The Murrawombie deposit is currently being mined by underground methods. Future mining will include open pit production.

Underground mining is in progress under the existing 130m deep open pit. The underground operation is accessed via a portal in the North wall of the pit. A standard 1 in 7 decline is developed in the footwall of the deposit and mining is by small open stopes.

Future open pit mining will be an expansion, by push back of the south eastern wall, to recover the remnant shallow resource. The pit expansion is scheduled to be mined as the last stage of production from the deposit. This will avoid the complications of simultaneously mining a pit above an operating underground mine. No crown pillar will be left to separate open pit and the underground workings.

The base of the existing pit void is at 5070mRL (130m below surface). Portal access to the underground mine is located at 5115mRL, (100m below surface).

The deposit has multiple lodes of mineralisation that are separated by waste. The lodes are numbered 101 through to 115 and modelled as separate geology domains. Mining methods vary slightly between the lodes. Not all lodes are economic to mine.

The underground mine is accessed by a decline mined at 1m vertical in 7m horizontal. Mining uses conventional mobile equipment commonly used in Australian mines. Ore and waste are hauled to surface by diesel powered truck. Ore is hauled from the Murrawombie site to the Tritton ore processing plant by road train trucks.

The underground mining method is small open stopes, or bench stopes, followed by backfill with dry waste rock fill. Mining sequence is bottom upwards. Cemented rock fill is used where backfill walls are exposed along strike in the extraction sequence. Lodes are generally mined from the hanging wall position back towards the footwall. Predominantly a sublevel interval of 20m vertical is used. The interval is selected to allow for flexibility in design to adapt to rapid change in the geology in the vertical dimension. There are significant structural controls (faults) over the mineralisation that influence the short scale geology, and these must be considered in final stope design. A 20m sublevel interval is important to support this design flexibility.

Sub level open stope mining generally extracts the full width of the orebody and 18m along strike. Stope stability is challenged in some stopes that are close to shear structures in the hanging wall. The shears often contain low strength graphite rock that is difficult to keep stable. Use of stiff cemented rockfill and short strike lengths on stopes helps to control dilution.

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Two mines were operational in the year; the Tritton and Murrawombie underground mines. The Tritton underground mine supplied the majority of the ore (1.04 million tonnes) to the processing plant. The Murrawombie underground mine produced the higher grade ore that fills the remaining ore milled.

Copper, silver and gold are recovered by crushing, grinding and conventional flotation of sulphides to produce a copper concentrate.

Concentrate from the Wemco cells is directed to final concentrate recovering 70% of total copper.

Primary rougher tails are pumped to conditioning tanks before two parallel banks of ten 8 m³ Dorr Oliver (5) rougher and (5) scavenger cells. Rougher concentrate is then sent directly to rougher cleaner while scavenger concentrate is sent to regrind.

Regrind is achieved by a 2.0 m dia x 3.4 m 150 kW ball mill in closed circuit with Cavex hydrocyclones. The underflow reports to regrind and overflow to scavenger cleaner, roughe ........