Human Interaction with the Rock
Cycle
Tara Lead and Zinc Mines
Learning Outcome
 Identify the ways humans use rocks in Tara
Mines
 Discuss the impact this has on the Rock Cycle
Mining in Ireland
• Important economic activity
• Employs 6000 people
• Generates over 1 billion euro annually
Lead
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Valuable
Widely used
60% of all lead is used in lead acid batteries
Has many other uses;
– Plumbing
– X-ray gowns
– Ammunition
– TV & Computer screens (blocks radiation)
Zinc
• Galvanising steel (prevents rust)
• Zinc dust & compounds used in;
– Cosmetics
– Plastics
– Paints
– Ink
Tara Mines
• Navan, Co Meath
Formation of Lead & Zinc
• Rock containing metal is called ore
• Carboniferous limestone
• Formation of ore linked to movement of groundwater
through the rock
• Seawater seeped into the rock
• This was heated by geothermal energy from inside
earth
• As the hot seawater (brine) moved through the planes
and joints, it dissolved small amounts of lead and zinc
out of the rocks
• The rich layers of ores within the rocks are called veins
Human Interaction with Rock Cycle in
Tara
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Construct shaft mines
Extract ore
Disposal of waste products
Transport systems
General Info
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Shaft Mine
Europes largest zinc mine
5th largest zinc mine in the world
Uses state of the art, remote control
technology and computerised systems
• Local economy in Navan has benefitted
financially
Employment
• 700 Jobs
– Chemists
– Environmental Scientists
– Miners
– Geologists
Mining in Tara
• Output transported to Norway, Finland &
other European countries
• Lead and zinc ores formed in faulted
limestone in Navan, over 350 million years ago
• Lie 50 – 900 metres below the surface
Extraction
• Stope and Pillar
• Large areas (stopes) blasted out and pillars left
standing to support them
• Modern computerised machinery used to
bring the ore to the surface
On the Surface
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Rock crushed into powder
Chemically treated
Dried to form metal concentrate
Then transported to Dublin Port
Further process details
• Water used is recirculated and reused
• Sediment is extracted and stored
• Backfill may be needed in the stopes, cement
and water pumped through the boreholes
Process Mill
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Operates continously
12 hour shifts
Highly computerised
On-site laboratory –analysis tests on rock
samples
Environmental Protection
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Landscaping to reduce visual impact
Wetland areas to treat water
Sheep grazing areas
Noise and Dust levels constantly monitored
Regular reports to the EPA
Spin-Off Effects
• For every one job in Tara, three indirect jobs
are supported.
– Eg; Caterers, Accountants, Truck Drivers, Safety
Consultants, Metallurgists
Future
• 2009; Threatened with closure
– Demand for zinc to galvanise car bodies fell
• However continued demand for zinc from
China and India
• Mine life extends past 2015
Keywords
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Mining
Ore
Extraction
System
Environmental Protection
Exam Question
• ‘People interact with the rock cycle in various
ways.’ Examine this statement using an
example you have studied.
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Human Interaction with the Rock Cycle