The Lik deposits are examples of a large group of deposits broadly referred to as sedimenthosted zinc-lead-silver deposits.

The Lik deposit is hosted in the upper part of the Ikalukrok Unit of the Kuna Formation. At Lik, the immediate host rocks are carbonaceous and siliceous black shale, with subordinate black chert and fine-grained limestone. These rocks strike broadly north-south and dip at approximately 25° to 40° to the west . The massive sulfides are overlain conformably by rocks of the Siksikpuk Formation. The sequence is overridden by allochthonous rocks that form high hills north and west of the deposits.

The mineralized sequence is cut by a number of minor faults. Recent drilling has demonstrated that several of the interpreted faults may not exist, or the movement on the fault is minor. The most significant of these faults is the Main Break Fault. While the plunge of the northern end of the Lik deposit increases to approximately 25° to 42°, it is no longer apparent that there is a break separating the Lik South and Lik North deposits. It is also unclear whether there is a change in strike north of the fault, or whether the change is more apparent due to topography.

Recent work appears to show that the fault does not exist, or its effects are very minor. The division into two parts is maintained and the boundary is taken as Section 13800N for this report. As presently tested, the largest lens, the A Lens of the Lik South deposit, is approximately 1,100 m long and 600 m wide and much of it is flat-lying. It contains the bulk of the tonnage in the Lik South area. The second largest lens, B Lens, is approximately 500 m long, up to 200 m wide, and averages approximately 120 m wide. The R Lens is approximately 400 m north-south, 100 m east-west, and up to 5 m thick and lies about 6 m above the A Lens. Mineralization in the Lik South deposits has been tested down dip to a depth of approximately 150 m to 200 m.

The Lik North deposit is approximately 700 m long and 350 m wide. As with the Lik South deposit, mineralization is interpreted as occurring in a number of lenses, with most of the mineralization present in a single lens referred to as the North Lens in this report. The North Lens plunges at about 25° to 42° and has been tested down dip to a depth of about 300 m.

The deposits strike broadly northerly and dip westerly at approximately 25° to 40°. The mineralization comprises irregular, stratiform lenses. The mineralogy of the sulfides is simple and comprises pyrite, marcasite, sphalerite, and galena, with rare tetrahedrite, bournonite, and boulangerite. Gangue minerals include quartz (as chert), clay minerals, carbonate, and barite. Noranda recognized six different ore types in its logging of drill core (Scherkenbach et al., 1985). Sulfide grain sizes and grades vary between different ore types. Maximum sphalerite grain size is about 100 µm.

The deposit will be a conventional, open pit, truck-and-shovel operation. A mill feed of approximately 5,500 t/d is planned over a nine-year mine life. There will be a small quantity of pre-strip material in Year -1, with a full production ramp-up in year 1. The throughput rate in Year 1 was reduced to 80% of full capacity to reflect mill construction and start-up time.

The grinding circuit will reduce the size of the crushed material to a product size P80 of 40 µm. The grinding process will be a two-stage operation with the SAG mill followed by one ball mills in closed circuit with the cyclones. A pebble crusher will be included in closed circuit with the SAG mill to handle coarse pebbles from the SAG mill discharge screen. The grinding circuit will process ore at an operating rate of 248 tonnes per hour.

Water and lime will be added to the SAG mill feed as required, and to maintain the slurry density at 74% solids. The SAG mill will operate at a critical speed of 76.9% with a nominal 12% ball load. Discharge from the SAG mill will be directed to a vibrating screen. Undersize from the screens will be discharged to the cyclone feed pump box, and oversize material (15-25% of new feed) will be sent to the pebble crusher by conveyor. The crushed material from the pebble crusher will be returned to the SAG mill. SAG mill discharge will combine with the ball mill discharge in the cyclone feed pump box. Slurry from the cyclone feed pump box is pumped to a cyclone clusters. Process makeup water and the required reagent will also be added to the cyclone feed pump box.

The overflow from both hydrocyclones in grinding circuit will feed to carbon pre-flotation circuit to remove the organic carbon from the ore prior to lead rougher flotation. Carbon pre-flotation circuit includes rougher and cleaner stages. Carbon pre-flotation cleaner concentrate containing most of the organic carbon will be discharged to the tailings thickener and the carbon pre-flotation rougher and cleaner tails, which contains the valuable minerals, will feed to the lead (Pb) rougher flotation circuit.

The carbon pre-flotation rougher and cleaner tails, which conclude the feed to the lead rougher flotation, will be conditioned in the lead rougher flotation conditioning tank. The flotation reagents will include lime, zinc sulfate, promoter 3418A and methyl isobutyl carbinol (MIBC). The lead rougher flotation circuit consists of eight flotation tank cells (six rougher and two rougher scavenger). The concentrate from the rougher and rougher scavengers are combined and sent to the regrind circuit. The rougher scavenger tail will be forwarded to Zinc flotation conditioner tank.

The lead rougher concentrate will be reground to a particle size of P80 of 10 µm in a regrind mill complete with a cyclone cluster. The overflow from the cyclones will gravity-flow to the lead cleaner circuit, the underflow of the cyclones will feed to the regrinding mill for further regrind.

The lead regrind cyclone overflow will be cleaned in three cleaner stages. The first stage of cleaner flotation includes four convention cells. The 1st cleaner concentrate will be fed to the 2nd cleaner and the 2nd cleaner concentrate feeds the 3rd cleaner flotation circuit. For the 2nd and 3rd cleaner stages, three conventional cells and four conventional cells will be used, respectively. The 1st cleaner flotation tailings will be further floated in two cleaner scavenger flotation cells. The concentrate product from the 1st cleaner scavenger flotation will be sent to the lead regrinding cyclone feed pump box, and the tailings will be advanced to the zinc flotation circuit. The tailings from the 2nd and 3rd cleaner flotation stages will be returned to the head of the preceding cleaner circuit. The final lead concentrate will be sent to the lead concentrate thickener.

The tailings from lead rougher scavenger and lead 1st cleaner scavenger will conclude the feed to the zinc flotation circuit. The slurry will be conditioned in the zinc conditioning tank prior to flotation. The flotation reagents will include lime, copper sulfate, SIPX, and MIBC.

The zinc rougher flotation circuit consists of one bank of eight rougher tank cells and an additional bank of four rougher scavenger tank cells. The concentrate from the rougher and rougher scavengers will combine and report to the zinc regrinding circuit. The rougher scavenger tails will be transferred to the tailings thickener for thickening prior to being discharged to the tailings facility.

The zinc rougher concentrate will be reground to a particle size of P80 of 8 µm in a regrind circuit consisting of mill in closed circuit with a cyclone cluster. The overflow from the cyclone cluster gravity-flows to the zinc cleaner circuit, while the underflow of the cyclones will be recycled back to the regrind mill. Process water will be added to the regrind cyclone feed pump box to adjust the feed to the cyclones as required.

The zinc regrind cyclone overflow will be cleaned in three cleaner stages. The first stage of cleaner flotation includes four tank cells. The 1st cleaner concentrate will advance to 2nd cleaner circuit and 2rd cleaner concentrate will advance to the 3rd cleaner circuit for a final stage of cleaning to produce the 3rd cleaner concentrate. The 1st cleaner flotation tailings will be further floated in a scavenger circuit. The concentrate product from the 1st cleaner scavenger flotation will be sent to the regrinding cyclone feed pump box, and the tailings will be sent to the tailings thickener. The tailings from the 2nd and 3rd cleaner flotation stages will be returned to the head of the preceding cleaner flotation circuit. The final zinc concentrate will be sent to the zinc concentrate thickener.