Mining

	Boroo's conventional open pit mine produces 6,500 tonnes of ore per day.

The Boroo mining operations are based on conventional open-pit methods to mine 6,500 tonnes per day of ore. Waste tonnage stripping rate is currently higher than the remaining life-of-mine strip ratio of 3.7, but will incrementally decrease from 42,000 tonnes per day in 2006 to 35,000 and 12,000 tonnes per day in 2007 and 2008, respectively.

The mine operates two 12-hour shifts, seven days per week. Blast hole drilling is carried out with three rotary drill rigs using down-the-hole hammers and one rotary-percussion drill rig. Blast holes in ore areas are 114 millimetre diameter drilled on 4.25 by 3.7 metre patterns, 5.5 metres deep. Waste is drilled with larger diameter and deeper holes and wider spacing. Blast holes are loaded with an ammonium nitrate and fuel oil mixture (ANFO) using bulk explosives trucks and detonated using non-electric blasting systems.

Mining is done on five metre benches. Two 2-1/2 metre cuts are used in ore and waste. At the pit walls, a five metre wide catch bench is left at every second mining bench (10 metre vertical).

principal rock handling equipment includes two hydraulic excavators and eight 50-tonne haul trucks. The waste rock mined is deposited on waste dumps immediately adjacent to the individual pits.

Additional mining equipment includes two large front-end loaders for ore handling and blending, a three cubic metre excavator for mine services work, three tracked dozers for the maintenance of waste dumps and benches and two graders for the maintenance of the roads and bench floors.

Ground water is currently being encountered in Pit 5. Emulsion-type explosives are required for blasting but dewatering has not been required. Drill hole information indicates water may occur in individual perched lenses rather than as a continuous water table.

Grade control in the pit is performed by sampling of blast hole cuttings and sorted according to grade. The blast hole assay data are determined at a laboratory in Ulaanbaatar and combined into an ore control model that is used to determine the boundaries for the various grade categories and to estimate monthly pit production.

Milling

	The first pour at Boroo, which began commercial gold production on March 1, 2004.

The Boroo mill features a conventional design that consists of crushing, grinding, gravity concentration, cyanide leaching and gold recovery in a carbon-in-pulp (CIP) circuit. A jaw crusher reduces the ore to 100% minus 20 centimetres. The crushed ore is fed directly to a semi-autogenous mill (8.5-metre diameter) or to a temporary coarse ore stockpile from which it can be reclaimed during crusher maintenance. Cyclones part the ore into two streams, with the cyclone underflow reporting to the ball mill. About 17% of the total cyclone underflow reports to the gravity circuit, which consists of two 750-millimetre Knelson concentrators followed by an Acacia reactor where the gravity-recovered gold is leached in high cyanide solution.

The cyclone overflow is thickened prior to the leaching circuit that consists of two pre-leach tanks where air is injected, followed by six CIP tanks. Gold in solution from the leaching circuit is recovered on the carbon in the CIP circuit and subsequently stripped from the carbon and again put in solution to be recovered by electrowinning, followed by smelting and the production of a doré bar.

After processing, tailings are detoxified using a modified INCO air-sulphur-dioxide process. Heavy metals are removed by treatment with ferric sulphate. The tailings are discharged by gravity to the permanent tailings facility five kilometres from the process plant and 135 meters lower in elevation. During non-freezing periods, water from the tailings storage facility is re-cycled to the plant for re-use to the degree practical.

The mill was designed with a capacity to process 1.8 million tonnes of ore per year (5,000 tonnes per day) and has consistently exceeded design throughput and is now producing at a rate of 2.3 million tonnes of ore per year (6,500 tonnes per day). The gravity circuit recovers 40% of the gold contained in the ore and the overall gold recovery has been 92% project to date.