The Kinsenda deposit is more typical of the Zambian Copperbelt deposits and is geologically similar to the Mufulira, Chambishi and Chibuluma South mines in Zambia. The Kinsenda deposit marks the transition between the two sub-types of the Copperbelt, with deposits to the north of the Luina dome showing a strong dolomitic character with associated HG oxides close to surface.

The Kinsenda ore body is hosted in a thick sequence of coarse to fine-grained sandstones, siltstones and shales of the Lower Roan Group in the footwall of the Ore Shale Member, and is generically referred to as a “footwall orebody”.

Sub parallel horst (highs) and graben (depressions) features in the pre-deposition basement are suggested by rapid variations in the thickness of the basal units of the Lower Roan both along strike and down dip. There is a strong correlation between the position of the Kinsenda deposit and the basement granite paleotopography, very similar to that of the Chibuluma South deposit. The host rocks occur as valley fill sediments in the down-faulted graben structures adjacent to growth faults that were active during sedimentation. The basement growth faults are oriented in a roughly ENE alignment and have a well-defined magnetic signature that can be traced into the basement rocks of the Luina Dome to the north of the Kinsenda deposit.

Kinsenda is a copper-only sulphide orebody consisting of predominantly chalcocite, bornite and chalcopyrite mineralisation hosted in detrital conglomerates, sandstones and argillaceous siltstones of the Lower Roan Group. The orebody consists of a number of vertically stacked, tabular mineralised zones varying in width from 1 m to 20 m, and generally occurring in the more porous, conglomerate rich zones directly below thick, less permeable siltstone rich zones.

The combined orebody occurs over a strike of approximately 2 000 m, dipping moderately at 25° to 30°. In plan view, the mineralised lenses form a series of partially overlapping, wedge shaped tabular bodies with a northwest-southeast strike orientation, which form laterally continuous lenses referred to as the upper upper ore zone (“UUOZ”), upper ore zone (“UOZ”), middle ore zone (MOZ”), lower ore zone (“LOZ”) and the basal lower lower ore zone (“LLOZ”).

The UUOZ and UOZ occur above the 285mL (285 m below surface) and have been largely mined out. The UOZ is separated from the MOZ by a low grade (less than 2% Cu) zone of approximately 40 m thickness. The waste separation between the other lenses is generally in the order of only a few metres. The LOZ is laterally discontinuous and is divided into multiple zones which can split and coalesce over relatively short distances, with two main components termed LOZA and LOZB.

The MOZ is the most extensively developed and has a maximum strike length of approximately 2 000 m, while the UUOZ has the shortest strike length of 250 m. On dip, the maximum length of the ore bodies can be up to 800 m, with ore thickness ranging from 1 m in peripheral areas to 22 m in the central portions. At least 60% of the mineralisation occurs in zones between 4 m and 12 m wide with an average width of all lenses of 5.9 m. The LOZA and LOZB zones have the highest grade and also constitute 64% of total mineral resource tonnage.

The mineralisation occurs predominantly as interstitial sulphides filling pore spaces in the coarse sediments. Copper oxides represent a maximum of 20% of the mineralisation with the proportion of oxides decreasing with depth. Cobalt minerals are rare and largely restricted to cobaltiferous pyrite.

The mine is a brown-fields project, having been previously operated between 1977 and 2002. At the time it was in a pillar recovery phase in accessible areas, following flooding in 1997.

The Kinsenda orebody dips at 25-30° and varies in width from 2 to 20 m, with the average width being 6 m. Three zones are present, termed UOZ, MOZ and LOZ, which pinch and swell and merge in places. The mine is divided into two distinct areas, the Western Mine and the Eastern Mine, with the eastern portion being regarded as a greenfields project.

Access
Three declines from surface were used previously to access the orebody. The DRA Report states that two of these, the UOZ and LOZ (A), could be rehabilitated to use as access ways. A fourth sub-incline, the LOZ (B), reaches the two deepest levels but is currently flooded and yet to be dewatered. A vertical shaft from surface, equipped with only one cage, serves 209L and 285L.

Sinking of a decline is from surface to 209L of the existing underground infrastructure has recomended. The intention is to use this for ore transport and it will be inclined at 8%, which SRK considers to be sound practice.

Mining Method
Conventional room and pillar was practised previously using labour intensive methods. DRA undertook a mining method selection study, which compared long hole open stoping (previously studied) with longitudinal and transverse drift-and-fill and re-evaluated them based on current more recent geotechnical knowledge.

The mining method proposed in the DRA Report is called both mechanised cut and fill and longitudinal drift-andfill (in the narrow orebody areas). It is essentially very similar to what is referred to as transverse drift-and-fill in the Snowden Report. There are only minor differences in the respective layouts proposed by Snowden and by DRA and SRK considers the method to be an appropriate one given the orebody geometry and geotechnical characteristics.

For the wider areas, DRA states that transverse post-pillar drift-and-fill will be used.

The mining method recovers the ore in horizontal slices, starting from the bottom slice advancing upwards. Pillars are left inside the stope to support the roof. The mined out stope is then back filled with waste rock, hydraulic tailings and the next slice mined working from the fill surface. DRA states that conventional mining will be practised in areas not suitable for trackless mining.

Access to the orebody will be achieved via a ramp access tunnel leading from the ramp, to the footwall drive that is developed on strike and on the same elevation as the third cut of the stope.

A strike access is developed in the footwall on each main level parallel to the orebody on the same elevation as the third mining cut, in order to gain access to the first cut of the stoping panel. From the footwall, a stope access tunnel is developed in the direction of the orebody at an angle of not more than -9°, an angle which allows all mechanical equipment to operate in that drive. SRK concurs with the philosophy.

It is proposed that the mine be divided into sets of three levels, called echelons, which are separated by 10 m thick sill pillars. Each stoping panel is 90 m long and consists of 6 panels.

Mined from underground using a mechanised longitudinal drift and fill, and long-hole stoping with fill mining method.

Rock Handling
Ore and waste rock will be loaded by LHDs, which will tip the material into trucks for transport to surface, with some waste during the early stages of the mine being hoisted to surface in the vertical shaft. Once stoping commences, waste rock will be used as fill material. SRK could not find any reference as to whether the cage in the shaft would be replaced by a skip to facilitate this.

Personnel will be transported using specialized trackless utility vehicles via the main ramp. Material will be transported in utility vehicles with interchangeable buckets (cassettes) designed for each purpose. Additional service fleet items will be scissor lifts, lube vehicles, graders, a compactor, scaler, etc. The equipment described above is standard for this type of operation and SRK concurs with the philosophy.

In 2020 Kinsenda Mine is developing a second ramp decline from 209m level as a capital development project to open up the East Mine resource.

The process plant comprises three-stage crushing (primary jaw crusher, semi autogenous (“SAG”) mill and pebble cone crusher).

The mill feed will be sourced from a 24-hour live stockpile with 4 apron feeders in an attempt to keep the feed as homogeneous as possible. As the stockpile runs down, a front-end loader will be used to push in the side walls. A mill feed silo was not considered due to cost implications.

The SAG mill is a second hand mill sourced from one of the gold mines in South Africa. The mill shell will be shortened to suit the requirement of 50 ktpm.

A pebble cone crusher was included due to the rock hardness of 17 kWh/t. This feature might not operate as envisaged because cast iron steel balls must be used to enable magnetic separation of the mill steel balls. Chrome steel balls proved to be more cost effective but the balls are then not magnetic. The scats and pebbles proved in other operations to be of a lower grade and can be discarded or mixed in with the feed as a circulating load.

The Kinsenda concentrator is designed to recover copper from a Cu sulphide/oxide ore body at a treatment rate of 50 ktpm at an average feed grade of 4.5% Cu over the LoM. The proposed Kinsenda concentrator design is based on well understood and proven technology. The process plant design criteria are based on the results of the suite of metallurgical tests carried out at Mintek. MDM did the plant design and it was completed in March 2011. Subsequently DRA was requested to finalize and optimize the design.

The RoM stockpile will have a capacity of 100 kt. This will be utilized at the beginning of the operation before the concentrator is commissioned. The intention is to keep the ore in this stockpile at a minimum once the whole operation is commissioned in order to reduce the process pipeline time.

The flotation cells selected are self-aspirating cells and as such a compressor for creating air froth is not required. This is the principle used by Wemco Flotati ........