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.

Rosh Pinah is an existing operating underground mine with well-established mining methods. The current mining method is LHOS without backfill using a Primary, Secondary, and Tertiary top-down extraction sequence. Mining using this LHOS method since 1969 has resulted in significant voids within the historical and currently mined zones.

The LHOS without backfill stopes are mined in a top-down sequence. Based on the ore width, access orientation, and the location of historical or planned voids, stopes are mined either transversely or longitudinally.

The longitudinal stopes are grouped on a level with a common access and only require a single slot with rings fired on retreat until the stope strike limits are reached.

Ore is sourced from five steeply-dipping zones, with an increasing proportion sourced from the western zones , as the eastern zone and southern-central zone are depleted.

Access to the production areas is via multiple interconnecting declines that provide fresh air intake into the mine.

The current mining fleet consists of mechanized mobile and ancillary fleet including development jumbos, production drills, loaders and 30 t trucks for haulage to an underground crushing and conveying system (notionally called the Krupp). Future plans include the use of 60 t trucks.

Current ore haulage is via a decline to the Krupp tip point comprising three ore silos in which to tip. Blending of the ore is conducted using the ore silos to maintain a consistent zinc and lead feed grade to the mill. Blended ore is conveyed from the Krupp to a surface crusher. Low grade mineralization is trucked to an underground void dedicated for this material. Waste material is trucked to dedicated historical stope voids.

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

The ROM ore is hauled from the underground production areas over a distance of approximately 4.2 km to the ore tipping location (Krupp) located some 320 m below surface. From the Krupp and primary crushing station, located underground, the ore is conveyed into the beneficiation plant through a series of conveyor belts for further crushing, screening, and grinding.

The ROM ore is fed through a grizzly to the primary jaw crusher at a rate of 140 tonnes per hour (tph) to 160 tph. The product is conveyed to the surface onto the primary screen where the oversize (+28 mm) is sent to the secondary cone crusher. Product from the crusher is sent back to the primary screen in closed circuit configuration. The undersize (-28 mm) from the primary screen is sent to the primary stockpile.

The secondary screen is fed from the primary stockpile at a rate of 100 tph to 110 tph. The oversize (+8 mm) is sent to the tertiary gyro-disc crusher. Crusher product is sent back to the secondary screen in closed circuit configuration. The undersize (-8 mm) from the secondary screen is sent to the mill feed stockpiles that act as a buffer between the milling and crushing circuit.

From the mill feed stockpiles, the ball mill is fed at a rate of 85 tph to 90 tph solids feed. The ball mill is a 1,000 kW Osborn ball mill measuring 12 ft by 12 ft.









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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 is sent to the lead regrind circuit where it is ground to a P80 of 25 µm. The regrind circuit consists of a high rate thickener, three 18.5 kW 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 are recycled back to the first cleaner and the final concentrate is 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 int ........