Underground Fluorspar Mining in the Peak District Milldam Mine

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www.britishfluorspar.com

Underground Fluorspar Mining in the Peak

District

Milldam Mine

Presented by

Mr Peter Robinson, Chairman, British Fluorspar Ltd

October 2015

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Location

British Fluorspar Ltd

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Peak District Orefield

Milldam Mine

Cavendish

Mill and

Longstone

Edge

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The Peak District National Park

• Mining/processing fluorspar from the Peak District

vein systems started in 1938, thirteen years before

the formation of the national park.

• Peak District National Park was established in 1951.

• The Park covers an area of 1,437 square kilometres

in an upland area of central northern England

between Manchester, Sheffield and Nottingham.

• Peak District is the most visited Park in the UK with

over 10 million visitors per year.

• The Peak District is a Living Landscape with a

combined community totalling over 40,000 people,

many local families go back for generations in the

area.

• Mining in the Peak District is an important part of both

the landscape and communities of the area.

• British Fluorspar is the only remaining miner in the

Park extracting strategically important Fluorspar from

the vein structures.

• British Fluorspar makes a significant contribution to

local employment, environmental management and

the economy of the Park.

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A History of Mining in the Peak District

• Peak District has a long mining history dating back to

Roman Times.

• Evidence of lead workings in the vein systems goes

back to the 13th Century.

• Lead from Derbyshire was an important source of

armaments for the defence of the realm from the 18th

Century.

• Fluorspar was first mined at the beginning of the 20th

Century initially for steel making and then for the

chemical industry.

• Modern Flotation processing plant was constructed at

Cavendish Mill in 1965 and operated continuously until

2010.

• Following a period of Care and Maintenance the mining

operation and plant were purchased by British

Fluorspar in 2012.

• Following refurbishment Cavendish Mill became

operational again in April 2013.

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“Old Man“ Lead Mine

• Lead first mined using antler bones

• Arrival Roman Empire metal mining tools in form

of hammers, chisels and adze/pick cross over

used

• Original lead extraction from open pits and

alluvial deposits - Simple smelting requirements

• Excavations extended to depth along vein walls

using timber support

• Openpits progress to underground workings

made as small as possible less timber and waste

• Great Hucklow vein found 17th Century below

100 metres of shale. Horizontal tunnels driven

into escarpment to base of shale to mineralisation

• Vertical stone lined shafts sunk by hand winze to

connect exploration drives and progress deeper

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“Old Man“ Lead Mine

Wrought iron hand tool

used to extract ore

Payslip from Mill Close

Mine

• Waste hoisted in kibbles by spinetree winches

• Deeper shafts developed during 17/18th century to hoist

men, materials and ore in tubs particularly with the later

onset of track mining and steam engines

• Shale gates driven as natural drainage adits. Also contract

“soughers” developed drainage systems “soughs” between

mines

• As mines reached water table “rag and chain” and “piston”

pumps used to dewater mineworkings to drainage “soughs”

• Lead veins selectively mined by hammer/chisel and pick

• Explosives introduced 20th century. Shot holes 14 inches

long and 1 inch wide drilled by single/double jacking –

Manual hammered steel chisels. Filled with black powder,

guncotton or TNT

• Lead mined at 75% pbs – waste including fluorspar packed

into workings

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Historical Track Mine Haulage

Old small scale tracked

mining lead ore tub.

Sallet Hole Mine

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Past and Present Mining

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Geology

Fluorite Mineral Resources

• Fluorite Mineralisation in the Peak District

orefield is contained within a series of near

vertical veins hosted in limestone from the

Carboniferous period.

• Hydrothermal mineral enriched veins are

formed in the cracks of fissures within the

limestone fault systems.

• The east-west trending fluorite veins extend

from surface or the base of the overlying shale

to the underlying volcanics.

• The primary veins range in thickness from 2 to

over 15 metres in width and grade from 15 to

over 50% CaF2.

• Stockwork, minor veins and replacement

mineralisation are also recovered from the

openpit operations.

• Mineralogy of the veins is predominately

Fluorite, Barytes and Galena.

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Hucklow Edge Vein System

Vein system

mined from

modern

Milldam Mine

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British Fluorspar Milldam Mine

Hucklow Edge

Milldam

Mine

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Mine Compound

• Mine compound located on site of a

former scrap yard, brownfield land

• Footprint of the compound limited and

excavated into cutting to reduce

noise, dust and visual impact

• Direct drift access down into the

Fluorspar vein from the compound

• Access to public highway avoiding

local residences

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Milldam Mine

• Modern underground mining operation

• Sub level open stoping

• Trackless mining

• Crown Pillar Support

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Mining Method

Sub Level Open Stoping

Ore zone horizon from shale to volcanics,

150 m depth

Haulage drives and access decline driven in

competent limestone host rock

Sub-level interval to 20 to 30 m

Cross-cut slit from haulage drive to vein at

10 and 20 m intervals

Underground drives dimensions: 3.5 m to

4m to accommodate 20 tonne ore haulage

truck

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Mining Method 3 Dimensional View

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Mine Plan Model

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Underground Mining Operations

• Modern trackless mine which utilises diesel power rubber tyred mobile equipment.

• Remote controlled 7 tonne scoop trams are used to load the ore from the stope drawpoints into 20 tonne dump trucks for haulage to surface.

• Mine operates a three 8 hour shift pattern Monday to Friday – with periodic works on Saturday morning.

• The mine has been redeveloped to produce up to 150 000 tonnes of run of mine ore per year for at least the next 20 years.

• Full production during day and afternoon shift. Long hole drilling ore stopes, blasting, remote ore loading from stope drawpoints and haulage to surface.

• Drilling and support work undertaken on Night Shift.

• Waste rock packed underground all shifts.

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Crown Pillar Systems

• Top section the vein system supported at “Shale Contact” to prevent subsidence and dilution of the mined ore within stopes

• Natural Crown Pillar left in-situ (5 to 10 metres) where vein splits, pinches and strong at shale contact

• Artificial Crown Pillar – ACP constructed where vein weak and thick at shale contact

• ACP – Row of full grouted rock bolts across vein. 3 metres below shale contact at 1 metre centres.

• Old workings and cavities at contact sealed by grout

ACP support

system

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Sequence of Mining Operation

Drill and Blast

Stope Drawpoint

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Sequence of Mining Operation

continued

Ore Transfer Transport to Plant

Ore Loading Underground Transport

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Underground Equipment Fleet

Modernisation Milldam underground trackless mining equipment

Scoop TramLong Hole Drill

Development Drill20 Tonne Truck

Loader

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Major Underground Hazards

• Inrush linked to old lead workings and underground water aquifers through shale contact.

• Ground Control – Massive Strong Limestone and Footwall and hanging wall rocks. Localised weakness near faults, fractured ground and mineralised veins. Strong exposed near faults, fractures on ground and mineralised vein – Selective rock bolts/mesh

• Ground Control – Mineral vein system weak. Vein drives steel arch and timber boards support for long hole drilling in stopes. Ore drawpoint operated by remote controlled loaders.

• Fire – Major risk engine tracked equipment. Diesel engines

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Milldam Mine Plan

• Existing underground development extends along the vein over 2000 metre strike, average depth 110 metres

• Mine plan split in to three phases , west to east

• 2.5 million tonne plus resource of good quality fluorspar ore

• Mine life 20 years

• Potential extended mine life - west

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Sub Level 2 Plan

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Future Mining in the Peak District

OPEN PIT versus UNDERGROUND

MINING

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Environmental Impacts

Key Open Pit Adverse Impacts

Open Pit Underground

Visual Screen Workings Open Pit Workings Mine compound

Noise Equipment Sound Protection High High

Dust Water Suppression Periodic None

Vibration Limit Scale of Blasting controlled controlled

Open Pit Footprint Minimum Working Area/Void High n/a

Public Hazards Boundary Treatment High Low

Water Discharge Treatment Suspended Solid Natural

Openpit

• Vein mineral extraction by openpit method is a temporary land use.

• High operational impact.

• Openpits are progressively restored to return the land to beneficial after use once the mineral has been extracted.

Underground

• No damage to surface

• Limited restoration requirement

• Mine workings low impact

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Comparison of Open Pit and

Underground Mining Ore Quantity Trends

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Open Pit Mining Underground Mining

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Vein Mineral Mining for the Future

• Peak district has a substantial resource of unmined fluorite rich vein systems which have the

economic potential to contribute to the long term STRATEGIC NEED for FLUORSPAR.

• Ore will be mined increasingly from underground drift mines and less from narrow steep openpit

quarries.

• Open Pit: Environmental and Social permitting in Peak District. Long, detailed bureaucratic and

expensive making new open pits cost prohibitive underground permitting simpler, less controversial

with accepted minerals policy.

• Cost per tonne of open pit ore increasing due to escalating permitting costs, environmental mitigation

measures and restoration cost provisions.

• Cost per tonne of underground ore decreasing with increasing use of modern trackless mining

equipment, reducing blasting costs (Slurry Explosive), more efficient drilling equipment and support

measures.

• Milldam has developed an efficient underground model for mining to 5 to 10 metre wide, vertical vein

structure using small scale 20 tonne truck/7 tonne scoop trams.

• Higher ore grades from deeper underground workings.

• Cost per Run of Mine tonne per contained unit of Fluorspar from Milldam Mine 30 to 40% cheaper

than equivalent from our open pits.

Underground Fluorspar Mining in the Peak District Milldam Mine

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