The Lac Herbin deposit is a narrow veins deposit type. The mineralization is contained within 12 shear zones.

A total of 12 shear zones are observed at the Lac Herbin mine, namely LH (Lac Herbin), WE, S1, S2, S3, S4, HW, HW2, HW2 Br, HW6, Bonanza (BZ), FL and several very localized flat veins.

Many of these shear zones contain quartz tourmaline veins, sometimes mineralized with pyrite, chalcopyrite and gold, and locally faulted. The dyke-controlled auriferous shear zones are recording a north-south shortening. The ore shoots generally plunges west but locally the plunge is controlled by intersection between two shear zones. Alterations associated with shear zones are variable. Hematization is strong and often observed in S1, S3 and LH structures. Widespread carbonatization occurs in shears. Chloritization or sericitization is present in shear when a mafic dyke or a felsic dyke is associated with the shear. A blurred texture marked by the disappearance of feldspar in favour of silica and chlorite is common at the Lac Herbin deposit. At the Lac Herbin deposit, correlation between blurred diorite and sub horizontal quartz tourmaline veins is observed on cross section; but becomes less obvious for vertical shears. The economic mineralization occurs in lenses where sulphides are present and there appears to be a strong relation between pyrite content and gold values. Also, coarse-grained pyrite is particularly associated with high gold values.

The longitudinal long hole mining method and a variance of it, called “Selective Short Hole” (SSH), will be mostly used to mine the reserves. The classification of the rock mass is adequate and with limited stope dimensions, good mining practice, these mining methods can be productive with a minimised percentage of dilution.

Generally, the mining blocks will be of a maximum dimension of 60 m in length and 60 m in height. The principal access, located at the base of these blocks, will be developed from the main ramp. In certain cases, a secondary ramp will be excavated to reach mineralized zones. These 3.6 m X 3.8 m drifts are excavated with mechanized equipments. These drifts are also for ore and waste transportation between the zones and the main ramp. Thereafter, the ore charged in trucks and hauled to surface.

Either conventional or Alimak raise are driven from the main access to give access to the sub levels. The lateral ore development (sub levels) will generally proceed on both side of the vein to the limits of the mineralization. Most of lateral development will be accomplished by conventional method. Conventional rock support will be installed in various developments.

Production drilling will be performed by long hole drills mounted on a 4 wheel autonomous carrier. The diameter of drilling will be 2.5 inches and length of hole limited to 15 m. Typical performance for that type of drill is about 75 m per shift. The same equipment will be used for drilling 4 m to 8 m cable bolts and 1.5 m x 1.5 m slot raise. The production holes will be surveyed if possible to control deviation. The production holes will be charged with emulsion explosive. When required, electronic detonator will be used to improve fragmentation and limit over break on the walls.

The mucking of the stopes will be done laterally using remote control scoop trams. The ore will be mucked to a secondary mucking point or loaded directly in 30 t haulage trucks.

Aurbel Mill:
The Crushing Circuit's capacity is 125-150 tonnes/hours, consisting of a jaw feed bin and pane feeder 4' x 16' with 36" x 48" jaw double toggle plates, driven by a 200 H.P. motor, followed by a Gyratory 16" x 50" crusher driven with a 150 H.P. motor and two Allis-Chalmers 6" x 51" cone crushers. The screening is made with two 6' x 16' double decks screens (3/8 "). It requires a total of 6 conveyors to transfer the ore in the different steps to finally get to the mill's ore bins (2 ore bins of 800 metric tonnes).

The Grinding Circuit is equipped with 5 grinding mills, one rod-mill and 4 ball-mills having a total of 800 kW and a single stage of classification consisting of three 10" cyclones. The conveyor feeding the rod-mill is equipped with a weightometer which measured the wet tonnes reported by the mill. Mill-reported dry tonnes are calculated based on the moisture found in the belt feed sample There are also two Knelson concentrators for the free gold recovery that are not currently in function.

The Flotation Circuit, begins with a conditioner tank, followed by an Outokumpu flash tank, 16 Agitair cells # 48 (2 banks of 6 units and 1 banks of 4 units) these can be used as required circuits for different ore treatment. There are no cleaning cells and the overflow of bank #3 is returning to the grinding circuit. The flotation concentrate is sent to a lixiviation circuit, passing by a 28' diameter thickener for density control of the leaching and water recovery (reclaim water) to be reused in grinding circuit. The underflow of the rougher cells goes directly to the tailing pond. The flotation concentrate tonnage represents around 8% of the initial feed tonnage.

The cyanidation circuit is composed of four leach tanks. The overflow of leach tank # 1 goes to a disc filter for a primary stage of filtration. The solid is then repulped and transferred to leach tank #2. Tank #2, 3 and 4 are overflowing from one to another by gravity to a 28' thickener and finally to the last filtration step. The first tank's size is 20' x 20' and the three other tanks are 14' x 14'. These tanks are equipped with Door Oliver mechanisms, rake types and airlifts.

Cyanide is added to the first and second tank and the retention time is around 4 days when the grinding circuit tonnage is 600 metric tonnes a day.

The filtration circuit is equipped with a disc filter 6’ x 9’ and an 8’ x 10’ drum filter. Theses filters are complete with, individual repulper, filtration tanks, filtration pumps and are interconnected to two parallel rotary vacuum machines and driven by 350 H.P.

The second thickener is used to control filter feed densities, clarify filtrate solution, and all the floor wash resulting from spillage in the cyanide operation, thus preventing the mix of cyanide content pulp or solution into the flotation process.

The filtrate solution from the filters is sent to a 28' thickener. The overflows from the thickener is pumped to two 14' x 14' preg tanks, and then pumped to a 29 bag 54" x 96" wide clarifier system and the solution passes thought a 44" x 96 Merrill-Crowe tank maintain by vacuum. The bottoms of the Merrill-Crowe tanks are connected with one 11"-2" pumps feeding a two 24 -36" x 36" frame Perrin Presses, injecting zinc dust and lead acetate at the pump suction, which generates gold concentrate in the presses.

The solution is then gold free, transferred in a V-Notch with a flowmeter and then by gravity to a 14' x 14' barren tank. The barren solution is used for filter wash. The concentrate resulting of that process is then ready for refining into gold bars. The final product will contain certain impurities. The gold bars must be sent to a refiner to be remelted and then processed into a 99.9 % pure gold product.