The Rosh Pinah mine is a reworked classic SEDEX type deposit comprising a primary banded sulphide exhalite, part of which was carbonatized with associated remobilization and enrichment of sulphides. The secondary carbonate ore carries the higher, economic, basemetal values.

The base metal sulphides at the Rosh Pinah mine are contained within the approximately 30 m thick ore equivalent horizon (OEH). In the Rosh Pinah mine area, the Rosh Pinah Formation has been shown to be at least 1,250 m thick.

The primary mineralization type at the Rosh Pinah mine is a silicified, grey to dark grey, finegrained and laminated unit locally called microquartzite mineralization. It consists of alternating millimetre to centimetre wide bands of sulphides (sphalerite, pyrite and galena + minor chalcopyrite) and is believed to represent a classic sedimentary-exhalative (SEDEX) style exhalite. The argillite mineralization at the Rosh Pinah mine would be similarly derived, but diluted with background benthonic argillite.

The mineralization occurs as breccia matrix and veins in silicified arenite lithologies (locally referred to as breccia mineralization) or as disseminated base-metal sulphides (locally referred to as arkose mineralization) and can reach economic grades. In places, the arkose/breccia mineralization gives indications of primary sulphide exhalations into an arenitic host. The breccia mineralization is commonly found in the immediate footwall to the ore horizon.

Carbonate mineralization is considered to be purely remobilized and provides the major economic component of the resource. Carbonate has replaced the arenites, both in the hanging wall and footwall of the ore horizon and a continuous range is observed from slightly carbonatic arenite (textures such as large, ghost feldspar grains occur) to pure carbonate, with all original textures lost. The carbonate has scavenged, concentrated, and remobilized base metal sulphides from the primary microquartzite mineralization. A near-total base metal enrichment of the carbonate mineralization gives rise to massive mineralization. When the carbonate has been leached out of the carbonate mineralization and the quartz grains and sulphides remain, the ore is locally referred to as sugary quartz mineralization.

The Rosh Pinah deposit is consequently presented as a series of discrete carbonate and exhalite lenses located on second-phase fold hinges or steeply plunging fold limbs connected by a partially attenuated exhalite- dominated ore-equivalent horizon.

The lenses have been separated into Primary, Secondary, and Tertiary classifications dependent upon their current materiality. The Rosh Pinah lens names are listed in Table 7-2 and are illustrated in Figures 7-5 and 7-6.

On average, WF3 comprises 7% arkose/breccia, 58% carbonate, and 36% microquartzite ore. It is graded from an arkose breccia dominated ore from section +90 to a carbonate dominated ore on section +210. From section +210 to +540, WF3 is almost exclusively composed of microquartzite and carbonate ore. Microquartzite ore becomes more dominant from section +330 further north. The average composition of WF3 from section +90 to +300 is 9% arkose/breccia, 68% carbonate, and 36% microquartzite ore. From +330 to +540 sections, it is made up of 2% arkose/breccia, 43% carbonate, and 55% microquartzite mineralization.

The WF3 deposit is interpreted to be a feeder zone consisting of numerous mineralized lenses with mostly secondary sphalerite and pyrite and is confined to the west by the Northern Fault. The mineralized lenses merge into singular lenses in some areas which is interpreted to be due to increased fluid activity.

The WF3 deposit generally dips northeast, striking northwest (325° to 145°) and almost midway through the deposit strike, the dip changes to southwest in the uppermost zones. Underground mapping of lithologies surrounding the orebody has revealed that WF3 is structurally controlled by shears zones and argillite bands. The ore zone contacts appear to be pervasively sheared in places probably due to the structural effects of the Northern Fault. Three faults are modelled and projected in place from the south composed of SF, SF1, and NF Splay striking parallel to the Northern Fault causing chlorotic schist in places. Microquartzites enveloping the ore have slightly undulating, graphitic, slickenside joint planes. The semi-tabular WF3 deposit has a highly irregular hanging wall dip and direction. Dip of the designed hanging wall varies from relatively flat to steep.

All mining is mechanized using drill rigs, scooptrams, and underground haulage trucks. Waste is hauled via declines and placed in previously mined stopes. Ore is dumped into an ore pass feeding a grizzly and primary crusher and is subsequently conveyed to the surface process plant.

Mining is done by sub-level open stoping. Ore development level spacing for open stoping is between 15 and 30 metres depending on the ore thickness with drive width dimensions of 6 metres wide and 4.5 metres high. Blast holes (76-millimetre diameter) for stoping are drilled from lower levels in a fan pattern using Atlas Copco Simba drill rigs. The burden is 1.9 metres and toe spacing is 2.8 metres. Emulsion explosives are used. Slot raises for stopes are drilled using an in-the-hole (ITH) 1.5 metre diameter raise bore machine. Extraction of stopes starts on the upper levels and proceeds down dip. No backfill is used in the mine and sill or rib pillars are left where required for geomechanical purposes.

The Rosh Pinah Mine utilizes a fleet of Atlas Copco Boomer drill jumbos, seven Elphinstone AD 30 haulage trucks, remote-capable Elphinstone scoop trams, including one R1300 unit, two R1600 units, and four R1700 unit, and two Atlas Copco Simba drills. In addition, there are various service vehicles including forklifts, scissor lifts, explosive loading units, a roof bolter, a scaler, a secondary breaking unit, and low-profile graders.

Annual mine production is typically 600,000 to 700,000 tonnes of ore from three different mining areas supplying a blend of ore types to the processing plant. The blending is carried out to manage the levels of copper, manganese and iron, which detrimentally impact recovery of zinc and lead, as well as to maintain a constant zinc and lead grade feed.

The process plant includes crushing, screening, and grinding followed by lead/zinc flotation and filtering to produce separate lead and zinc concentrates.

The run of mine ore is crushed in a primary crushing station, located underground from where it is conveyed into the beneficiation plant through a series of conveyor belts for further crushing, screening, and grinding. From the mill feed stockpiles, the ball mill is fed at a solids feed rate of 85 to 90 tonnes per hour. The ball mill is a 1,000 kW Osborn ball mill measuring 12 feet by 12-feet. Sodium cyanide is added in the mill to depress sphalerite and pyrite and Aerophine or Sodium Normal Propyl Xanthate (SNPX) is added to collect the galena. The milling circuit has two stages of cyclone classification in closed circuit with the mill to produce the lead flotation feed with 80% passing 106 microns. A third stage of cyclones dewaters the flotation feed slurry to an optimal density.

The product from the milling circuit is sent to a conditioner where frother is added before it passes on to four rougher tank cells. The concentrate from the roughers are sent to the lead regrind circuit where it is grinded to a P80 of 25 µm. The regrind circuit consist of a high rate thickener, 3 x 18.5kW stirred media detritors and a product tank. The product from the regrind circuit is sent to a first cleaner bank cell. The concentrate from the cleaner bank cell is sent to the lead column cell and the tails is recycled back to the conditioner. The rougher tails go to two scavenger tank cells. Tails from the lead column cell is recycled back to the first cleaner and the final concentrate sent to the lead concentrate thickener and belt filter for dewatering. The scavenger concentrates are also recycled back to the conditioner while the scavenger tails become the feed to the zinc circuit which first passes through two parallel intermediate thickeners. The main purpose of the intermediate thickeners is to recover and recycle process water back to the lead and milling circuit. The final lead concentrate from the belt filter is discharged onto a drying floor, where it is dried and stockpiled until loaded onto trucks for dispatch to the port of Luderitz.

The underflow of the intermediate thickeners is fed to two zinc conditioners in series where copper sulphate is added to activate the sphalerite, SNPX added to collect the sphalerite, lime (occasionally to depress pyrite) and frother added. From the conditioners it is fed to a rougher tank cell which has its concentrate sent to the zinc regrind circuit where it is grinded to P80 of 53µm. The regrind circuit consist of a high rate thickener, a 90kW stirred media detritor and a product tank. The product from the regrind circuit is fed to a cleaner cell. The rougher tails is sent to a series of four scavenger tank cells. The concentrate from the cleaner cell feeds the final zinc column which in turn produces the final zinc concentrate which is sent to the zinc thickener and belt filter for dewatering. The final zinc concentrate from the belt filter is discharged onto a drying floor, where it is dried and stockpiled until loaded onto trucks for dispatch to the port of Luderitz.

The tails from the cleaner cell is combined with that of the rougher tails that feed the scavenger cells. The final column tails and the scavenger concentrate are both recycled back to the conditioners. The scavenger tails is sent to the tailings surge sump from which it is pumped to the tailings dam.