Overview - The Lisheen mine is located in County Tipperary, Ireland. Geochemical, geological and geophysical work done in the area from 1986 to 1988 uncovered an anomaly and drilling in 1990 intersected the orebody returning grades in the range of 14.7% Zinc and 2.7% Lead. Drilling continued until the end of 1996 and had by then outlined a resource of 22.5 million tonnes containing 13.02% Zinc and 2.19% Lead.

Keywords   Ireland   lead   underground

Construction of the mine commenced in September of 1997 with first ore brought to the surface and first production of lead and zinc concentrates happening in September 1999 and October 1999 respectively. Various improvements have taken place over the years, in October of 2004 a pastfill plant was commisioned and by September, 1 million tonnes of paste was placed underground. By May of 2006 over 2 million tonnes of ore had been shipped from the Port of Cork.

Ownership Summary  Name: ANGLO AMERICAN PLC    Interest: 100%    Note: public Reference: 30 Nov 06

Employing roughly 345 people, the mine is capable of mining and treating 1.5 million tonnes of ore each year from which it produces an annualized 300,000 tonnes of Zinc in concentrate per year over the life of the mine.

With current reserves, the life of the Lisheen Mine is expected to be 14 years though exploration is ongoing to extend that further into the future.

Location - The mine is located near the Village of Moyne in County Tipperary, Ireland, the Lisheen zinc and lead deposit is located in the Rathdowney Trend, which stretches 40 kilometers, between the Towns of Abbeyliex to the North East and Thurles to the South West. The region is a broad plain drained by the Rossetown and Drish Rivers, tributaries of the Suir River, which flows into the Irish Sea at Waterford.

Location Summary Nearest Landmark: DUBLIN Distance from Landmark: 170km Direction from Landmark: SW Latitude: 52 deg 44 min N Longitude: 7 deg 40 min W Satellite Image: <click to view>

In common with much of Ireland, the area is characterised by cool, wet climatic conditions. Mean temperatures vary from 4.4 °C in January to around 15 °C in July, with an average humidity of 83%. Annual rainfall ranges between 700 and 1000 millimeters.

Land in the vicinity of the Lisheen Mine has traditionally been used for dairy farming, cattle and sheep rearing, forestry and peat farming.

Property - The mine sits on mining leases owned by Anglo American covering 463 hectares and is expected to have a 14 year mine life.

The Lisheen deposit lies at an average depth of 170 metres and comprises two distinct ore bodies, Main Zone and Derryville.

Deposit Summary Deposit Type: Massive Sulphide Primary Commodity: Zinc

The ore bodies are predominantly stratiform or flat lying, ranging in thickness from 1 to 14 metres. Close to faults, mineralisation may be substantially thicker, in some cases up to 30 metres. The stratiform nature of the ore bodies is typical of zinc deposits in Ireland and also occurs elsewhere in the world.

Reserves Summary Name: Lisheen Commodity: Zinc Class: Proven + Probable Tonnage: 10.6 Mtonnes Grade: 14.04 % Note: Containing 1,485,000 tonnes of zinc in concentrate. Reference: 30 Jun 06

The ore bodies comprise mainly sphalerite (zinc), galena (lead) and pyrite (iron). The deposit is high grade, with zinc to lead ratio of 5:1.

Definition drilling and exploration continues in the mine area and district to identify extensions to the ore bodies, as well as new deposits. More than 650 holes have been drilled to date.

Operation - Room & Pillar and Drift & Fill are the main extraction methods employed underground, with blast hole stoping used in thicker areas.

Mining operations are scheduled on a 2 shift per day, 6 days per week basis. The mine is accessed via a 1.5 kilometre long decline, 6.3 metres wide by 5 metres high. Underground drilling rigs bore holes in the ore face, which are charged with explosives and fired.

The resultant broken ore is removed by large Load Haul Dump (LHD) machines and loaded into trucks that transport the ore for crushing. The ore is first emptied onto 'grizzly' bars which prevent oversized material from entering the crushing chamber before being fed into the underground crusher.

Mine Production Summary  Mine - Lisheen    Capacity: unknown     Rate: 5,000 t/day Reference: 30 Jun 06

All material is removed by conveyor to the surface, where it is stored in a covered stockpile of approximately 25,000 tonnes live capacity prior to processing.

The mine works with a pull system of fans at the exhaust shafts, which pull air though the intake points to the exhaust points.The Main Decline is the main intake into the mine and is the main access for all personnel and equipment.

There are eight vertical shafts and one Main Decline for ventilation control to the underground workings, the intakes into the mine via the Main Decline, I31(Shaft) and Fresh Air Shaft (FAS) which is also the second means of escape for the miners.Of the remaining 6 shafts, one is decommissioned and the other five are used as Exhaust shafts, with high flow, low pressure underground fans with surface evasee's.

Because the Mine occurs in limestone terrain and is adjacent to bog lands, water has been a significant challenge in the design and construction of The Lisheen Mine. In the interests of miner's safety, a sound approach to groundwater management had to be implemented. Initially, surface de-watering wells were placed at the edge of the mining area. Later, a sub-horizontal well field was drilled within the mine, and this remains active.

Process - The mineral processing facility at Lisheen operates 24 hours a day, seven days a week, at a rate of 4,500 tonnes per working day.

The first stage of processing is comminution, which involves the reduction in size of the ore particles to separate valuable minerals contained in the ore from the non-valuable host rock.

From the covered surface stockpile, the ore is conveyed via 6 vibrating feeders onto a conveyor, which delivers it into a semi-autogenous grinding (SAG) mill. The SAG mill is a rotating cylindrical vessel containing 8-12% steel balls, in which the particle size of the ore is reduced. Substantially oversize discharge is screened out and conveyed back into the SAG mill for further grinding and the remaining slurry is directed to a cyclone for sizing.

The course overflow materials from the cycloning process are directed to a ball mill containing 40% steel balls, where further grinding takes place. The discharge from the ball mill is fed to the same cyclone as the finer materials from the SAG process.

The second stage of processing is floatation, a process used to separate the zinc and lead minerals from the ore. Air is pumped into the slurry, forming bubbles to which the minerals attach themselves. The mineralised bubbles form froth on the surface of the slurry, which overflows into launders and is pumped to the next stage in the process. The material that does not float is called "tailings".

Lisheen uses floatation lines for lead floatation and zinc floatation, each of which has 3 sections-roughers, column cleaners and cleaner scavengers. Slurry first passes through the lead rougher where, aided by the addition of specific reagents, the lead content is separated from the rest of the slurry or tailings.

The tailings then pass into the zinc floatation line where different reagents are added. After roughing, the zinc concentrates undergo a further comminution process known as regrinding, during which very fine particles of sphalerite are released before production of the final concentrate.

The lead floatation line upgrades the concentrate to 64% lead, while the zinc floatation line produces a concentrate of 54.5 - 55% zinc.

After floatation, the zinc concentrate may undergo an acid leach quality control process, which helps to reduce magnesium levels in the concentrate if required.

Processing Summary  Facility - Lisheen    Capacity: unknown     Rate: 5,000 t/day  Product    Commodity: Zinc    Quantity: 159,300 tonnes    Cost: unknown     Note: Metal in Concentrate  Product    Commodity: Lead    Quantity: 20,800 tonnes    Cost: unknown     Note: Metal in Concentrate Reference: 30 Jun 06

At this point the concentrates contain too much water for storage and shipping and must therefore be de-watered.

The first stage of de-watering is thickening. The slurry is fed into an un-agitated tank, where chemicals are added to assist the settling process by amassing individual particles into larger clumps. These solid particles of the slurry are then allowed to settle to the bottom before being raked gently to a central underflow pumping point.

The underflow of thickened concentrates is directed to the respective filtration stage for final de-watering. Using pressure filters (1 for lead, 2 for zinc), the moisture concentrate of the thickened concentrates is reduced to approximately 6% for lead concentrate and 8% for zinc concentrate.

Environment and Community - Following the completion of a comprehensive Environmental Impact Assessment, an ongoing environmental monitoring program was initiated in 1997 during construction. Monitoring of water discharge quality, air quality and noise levels will continue through the operational and closure phases of the mine.

Each month, some 60,000 environmental quality readings are taken at various points on the site. Ambient air and water quality and noise and vibration levels are monitored in the vicinity of the mining operation. The quality and ecological status of surface and ground water, soil and vegetation is also regularly monitored.

These readings are relayed to a purpose-built Environmental Information Office, which also houses a state-of-the-art laboratory where samples of water, air and soil are tested using the latest analytical equipment.

The environmental data collected at the mine is regularly submitted to the Environmental Protection Agency and is available for public inspection.

Once mineable resources at Lisheen are exhausted, a mine closure plan will be implemented to remediate the site, including the restoration of grassland and trees and the development of wetlands on the Tailings Management Facility.

The economic benefits to the mid-west region are approximately Irish pound35million due to annual expenditure on wages, good and services. Mining projects also contribute significantly to the development of local infrastructure, and this project has involved expenditure of some Irish pound4 million on local roads and some (Irish pound)2 million on upgrading local water schemes.

The Lisheen Mine has stated policy of employing local people. The Lisheen Mine employs approximately 345 people, 70% of whom are recruited locally. Lisheen is committed to training and developing staff to ensure their ability to contribute to the mine's operations and to afford them a career path to promotion opportunities.

The Lisheen Mine manages its operations in accordance with the highest international standards of health and safety (OHSAS 18001) and is audited annually by the National Standards Authority of Ireland (NSAI), with the aim of eliminating all injuries or accidents.