environmental impacts of mines &...

Environmental impacts of mines &

quarries

Dr. Wan Zuhairi Yaacob

Program Geologi

UKM

STAG3042: Environmental Issues

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STAG3042: Environmental issues

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MINING / Perlombongan (takrifan)

• Mining involves the extraction

of large quantities of rocks,

liquids and gases from the

depths of the earth

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Bingham Canyon Open Pit Copper Mine

Bt. Ibam, Pahang

Bt. Besi, Terengganu


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Jenis mineral (mineral classification)

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metallicNonmetallic


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DIFFERENT VIEWS about mining

• “Mining makes a mess of the countryside”– Disturb the land

– Overturn vegetables

– Destroy wildlife shelter

– Disrupt farming

– Waste piles

– Abandoned shafts

• “We have to mine minerals where we find them”– Essentiality of minerals

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Types of mining in Malaysia

• Tin/gold mining– Alluvial dredging

– Lode mining (hard rock)

– Open pit mining

• Gold from surface or underground

• Bauxite mining

• Copper from surface mining

• Coal mining

• Iron mining

• Industrial minerals– Barite; kaolin; clay; silica sand; limestone;

dimension stone.

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MINING METHODS

• SURFACE– Area strip mining

– Contour strip mining

– Open pit mining

– Auger mining

– Placer mining

• SUBSURFACE (coal mining)– Longwall mining

– Room & Pillar

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Potential mining methods in Malaysia

• Open pit mining and quarrying

• Surface strip mining

• Alluvial dredging

• Underground mining

• Solution mining

• Hydraulic mining

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POOR MAN’S METHOD

?

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Mendulang !!


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Mineral Deposits

• Primary

(at source – vein / telerang )

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• Secondary

(product of erosion

and deposition)

the deposit of loose surface

soil or gravel that contains gold.


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Surface Mining

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Surface mining requires large capital investment (primarily expensive

transportation equipment), but generally results in:

--High productivity (i.e., high output rate of ore)

-- Low operating costs

-- Safer working conditions and a better safety record than underground

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Open pit Mining & Quarrying

• Mineral deposits exposed to

the surface or close to it

• Removal of overburden or

waste rock

• Disruptive to local land form

• Removal and disposal of

large volumes of waste rock

• Problem if waste rock has an

acid generating potential

• Dewatering: depression of

local groundwater profile.

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Open Pit Mine

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Lowering of groundwater profile

Dry well

Erosion / pollution / AMD

Potential slip surface / landslide


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Open Pit Mine

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Open-pit mines are used when deposits of

commercially useful minerals or rock are found near

the surface; that is, where the overburden (surface

material covering the valuable deposit) is relatively thin

or the material of interest is structurally unsuitable

for tunnelling


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Open Pit Mine

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[movie]

../../../../Downloads/Mining/Surface Mining.flv

Overburden blasting

(peletupan lapisan penindih)

• Noise & air shock (air impacts) – kejutan udara

– Troublesome to people live within a radius of several miles (km)

from the site

• Magnitude of problem is depending upon:

– Depth and type of overburden

– The explosive factor (use less explosive per volume of

overburden)

– Amount of explosive detonated

– Population density

– Times of day during blasting (daylight hours only!)

• Ground vibration

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World’s largest man-made excavation

Bingham Canyon, Salt Lake City8/24/2009 18


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Surface strip mines

• Suitable for uniform layering, close to

surface mineralized material

• Eg: Coal; bauxite; iron

• The operation moves systematically

across mine area, exposing and

extracting the ore while depositing the

waste material behind.

• Ongoing rehabilitation / progressive

rehabilitation

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Lombong Bauksite Teluk Ramunia

(area strip mine)


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Alluvial dredging mines

• The most common method in Malaysia (historically !!)

• Extraction of tin-bearing material from alluvial deposits

• Creation of man-made pond over the area to be mined

• Use of floating dredges to extract the material

• The ore is processed into concentrate on the dredge and tailings

(waste) deposited behind

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Kapal korek (dredge)


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Alluvial dredging mines

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Hydraulic Mining

• Use high pressure water jets to break

up tin bearing ore

• Slurry is pumped to a gravity separation

flume

• Requires large quantities of water

• Management of resulting slurry

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How can water cut through steel?


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Hydraulic Mining

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Flume /

elevated box

structure

(wood) for

water channel

Hydraulic Mining

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Pahang (Jln K.Lipis-G.Musang)


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Gold Mine (Plaser)


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Auger Mining

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SUBSURFACE MINES

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Underground mining

• To extract mineral-bearing material (ore) which is too deep for surface mining (not economical!!) – why ??

• The method selected depends on:– Configuration of ore / orientation / shape (kedudukan bijih)

– Strength surrounding material (kekuatan batuan sekeliling)

– Ore strength (kekuatan bijih)

– Distribution of ore (taburan bijih)

• Less disruptive to land use

• Little or no waste

• Low impact rehabilitation

• Dewatering of mine & potential subsidence8/24/2009 31


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Two common methods of underground mining

(especially for coal)

• (1) Longwall mining

– Longwall (250-400m long) of coal is mined in a

single slice (1-2m thick).

• (2) Room-and-Pillar

– Ore is extracted across a horizontal plane while

leaving “pillars” of untouched material to support

the overburden leaving open areas or “rooms”

underground.

– “Retreat mining” = final phase, mine the pillar

Underground mining

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The advantages of longwall mining

• Better resource recovery (about 80% compared with about 60

percent for room and pillar method)

• Less roof support needed

• Higher volume coal clearance systems

• Minimal manual handling

• Subsidence is largely immediate, allowing for better planning and

more accountability by the mining company.

• safety of the miners is enhanced by the fact that they are always

under the hydraulic roof supports when they are extracting coal

The disadvantages of longwall mining

• Surface subsidence, which may considerably alter the landscape

above the mine


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The disadvantages of longwall mining


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Longwall mining

Hydraulic support

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Remote Control

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Movies

• Movie 2

• Movie 1


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../../../../Downloads/Mining/Longwall Mining.flv

../../../../Downloads/Mining/longwall.flv


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IMPACT OF MINING

THREE TYPES OF CHANGES:

1. Change in natural topography

Disturb the land; big man-made ponds/lakes

2. Change in hydrogeological condition

Aquifer beheaded; lost of groundwater

resource; groundwater contamination (AMD)

3. Change in geotechnical conditions

- deformation of rock mass (rock fractures;

poor grade)

- dislocations at the surface (subsidence/sinkhole)

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Impacts and benefits of mines and quarries

Impacts Benefits

Landuse changes Economic advancement

Surface habitat changes Employment

Surface water changes Social & medical enhancements

Groundwater changes Stimulation of secondary industry

Blasting vibration Provision of mineral resources

Noise Enhancement of technical skills

Elevated dust levels Enhancement of educational levels

Subsidence Access and infrastructure enhancements

Health impacts

Aesthetic changes

Chemical toxicity

Traffic changes

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MINING

(exploration, extraction)

Processing

(transportation, purification,

manufacturing)

USE

Disturbed land; mining accidents and

health hazards; mine waste dumping;

oil spills; noise; ugliness; heat

Solid wastes; radioactive materials

Air, water and soil pollution; noise;

safety and health; Hazards; ugliness; heat

Noise; ugliness; pollution of air,

water and soil;Solid and radioactive wastes,

safety and health hazards; heat

Environmental effectsSTEPS

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Environmental effects of extracting and processing minerals

Activity Potential Effects

Digging a mine and

removing ore from it

Surface mining: destroying habitat, farmland,

residences

Underground mining: sinking of land (subsidence)

Soil erosion; production of waste; toxic drainage

Concentrating the ore Production of piles of tailings; organic waste added

to tailings when the waste materials usually left near

a mine; toxic drainage

Purification

(chemical methods or

smelting and other high

temperature processes)

Air pollution by emmisions from smelter (As, Pb,

SO2, Cd).

Production of more waste (slag that is left after

smelting)

Energy waste (most energy used in extracting

minerals is used in smelting and refining)

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IMPACT OF MINING ON THE ATMOSPHERE

• Dust & Gases (fugitive dust)

– Opencast mining – blasting

– Escaping gases from rock/mineral

masses & machinery

– methane, carbon monoxide, nitrogen

oxide, sulphur compounds

• Burning waste tips – noxious

gases(SO2, NO2, CO, H2S)

• Respiratory diseases – black lung

diseases

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caused by inhalation, over many years, of small amounts of coal

dust.


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IMPACT OF MINING ON THE ATMOSPHERE

• Air Quality

– Fugutive dust

• Coal haul roads

• Unvegetated spoil surfaces

• Top soil stockpiles

• Coal stockpiles

– Potential problem in area of low rainfall,

high winds, erodable soil

– Solution: watering of road & stockpiles

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• Loss of farming land

• Degradation of ecological systems

• Land subsidence

• Waste tips

• Acid Mine drainage – pollutes water/soil

• Timber for roof support

• Plants are susceptible to atmospheric pollution– Photosynthesis affected by SO2, CO, CH

– Acid rain on soil, water, biota

IMPACT OF MINING ON THE BIOSPHERE

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• Damage on surface & subsurface

• Geomorphic change

• Surface subsidence

• Waste dumps

– Wind blown dust; spontaneous

combustion

• Landslides, rock & mud flows

IMPACT OF MINING ON THE LITHOSPHERE

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Subsidence due to:-

Multiple pillar failure

Pillars punching into

soft clay floor

The migration of

roof failure is

stopped by stable

strong roof


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Pembentukan crown hole / sinkhole

Lapisan tebal batu pasir

menghalang runtuhan dari

berlaku

Bumbung terowong adalah

lemah/tidak stabil (weak, thinly

bedded shales/mudstone),

terbentuknya crown hole

Pengaruh endapan quaternar

(superficial deposits) terhadap jenis

dan luas ketidakstabilan.

clay sand

dwzwy-geologi-2009

Collapse of

pillars

(narrow coal

pillars)

Punching

failure and

floor heave

(soft material;

clay)


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Stabilization of roof/roof support

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• Lowering of water table

• Mine water discharge to river

• Seepage from settling tanks

• Water is pumped into ground to

extract minerals (eg. Salt)

IMPACT OF MINING ON THE HYDROSPHERE

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ACID MINE DRAINAGE (AMD)

• The drainage of acidic water from mine sites

• May continue for hundreds of years

• High-sulfur coal & metallic-sulfide ore bodies

• Interaction of 4 spheres

– Lithosphere = minerals

– Hydrosphere = water

– Atmosphere = oxygen

– Biosphere = bacteria Thiobacillus ferrooxidans

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Rio tinto river, Spain.

Sg Lembing Pahang.


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1. ACID MINE DRAINAGE

• Acid mine drainage refers to water with high

concentrations of sulfuric acid (H2SO4)

draining out of surface or subsurface coal

mines.

• Simple weathering reaction:

• Sulfide minerals come into contact with

oxygen-rich water (sulfide oxidizes)

• EG: Pyrite (FeS2) oxidizes in water

(surface/gw), forms sulfuric acid


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Tindakbalas kimia pembentukan AMD

(AMD chemical reactions)

• 4FeS2(s) + 14O2(g) + 4H2O(l) ---> 4Fe2+(aq) + 8SO42-(aq) + 8H+(aq) (1)

• 4Fe2+(aq) + O2(g) + 4H+(aq) ---> 4Fe3+(aq) + 2H2O(l) (2)

• 4Fe3+(aq) + 12 H2O(l) ---> 4Fe(OH)3(s) + 12H+(aq) (3)

4FeS2(s) + 15O2(g) + 14H2O(l) ---> 4Fe(OH)3(s) + 8SO42-(aq) + 16H+(aq) (4)

Yellow Boy

pH acidic

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Iron hydroxide

Ferrous

Ferric

Pyrite

Ferrous

Ferric Iron hydroxide


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Environmental impact of AMD

• Degradation of water quality in surface

and ground waters – formation of Yellow

boy – iron (III) hydroxide

• pH of the water is lowered due to the

introduction of sulfuric acid

• Heavy metal ions can also be released

into the water as a result of mineral

weathering.

– Heavy metal ions: iron, zinc, aluminum,

manganese, cobalt, nickel, copper, arsenic,

selenium, cadmium, and lead.

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Mine Tailings

Closeup view of mine tailings.

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Thiobacillus ferrooxidans

T. ferrooxidans catalyzes the oxidation of FeS2,

producing ferric ions and hydrogen ions.

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A TEM view of T. ferrooxidans

(Transmission Electron Microscope)


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Excellent example of interaction of four spheres


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Bekas Lombong Bijih Timah

Sg Lembing, Pahang

• Underground

• Adit (horizontal opening

to the mine)

• Shaft (vertical tunnel)

• Horizontal workings off

the shaft are called

drifts, galleries or levels

(kolong)


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Bukit Ibam (Lombong Besi)


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Bukit Botol, Tasik Chini


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Bukit Ibam

Padang Piol, Jerantut

Ex-Bukit Panching, Kuantan

Bukit Charas


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TAMAT

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Pantai Bisik-Bisik, Kedah


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