PREN2620 Environmental Impact Assessment and Monitoring Techniques

1
PREN2620Environmental Impact Assessment and
Monitoring Techniques
Blasting and Environmental Research Group

• Dr. Mark Pegden

Department of Mining, Quarry Mineral
Engineering, University of Leeds
2
Water Monitoring Assessment TechniquesPart 1
3
Topics

• Water use in the mining industry
• Environmental problems with contaminants
• Acid Mine Drainage (A.M.D)
• Diffuse and point sources

4
Water in mining

• Extraction - Problem Suspended solids
• Hydraulic mining drills, cutters etc..
• Dredging auger, suction etc..
• Cooling Problem Thermal
• Pumps, compressors, crushers, mine power
  facilities heat exchange from facility to water

5
(No Transcript)
6
Largest Joy Continuous Miner in the world,
located at the Winsford Rock Salt Mine, UK
7
Water in mining

• Mineral Processing Problem Suspended solids
  in waste water, chemicals from process cycle.
• Screening, milling, flotation, cyclones and
  leaching water used to lubricate the crushing
  and process cycle
• Mineral processing can use up to 80 of the water
  in a mining operation.

8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
Water in mining

• Transport
• Problem Silt and chemical leakage
• Slurry pumping, backfilling waste
  solidified underground in worked voids.
• Vehicle Washing
• Problem Solids, oils and detergents

19
(No Transcript)
20
Other sources of water contamination

• Pumped Mine Water
• Problem Acidity, silt, oil, chemicals, ANFO
• Groundwater, rainfall, drilling and hydraulic
  machinery.
• Surface Runoff
• Problem oils, silt, chemical and acidity
• Overburden dumps, stockpiles, plant yards and
  waste dumps.

21
Other sources of water contamination

• Percolation
• Problem the release of mine water or waste into
  controlled waters.
• Tailings Dams, Lagoons, Dewatering towers, Dam
  walls
• Leaching
• Problem Leaching of chemicals and waste into the
  environment.
• Waste dumps, overburden dumps

22
Environmental problems with contaminants
23
Environmental Problems

• Oil
• Problem oil and grease in water
• Sources Machinery, or lubricating equipment.
• Effects Colouration of water. Interferes with
  re-oxygenation of water.
• Monitoring Visual assessment or a standard
  meter/probe

Control Good Housekeeping, use of an oil trap on
surface drains and settling ponds.
24
Environmental Problems

• Turbidity
• Problem Colloidal particles that dont settle
  out over time.
• Sources Nearly all operations of the mine
• Effects Discolouration of water, visual problem,
  effects aquatic life.

Monitoring Light absorption units Control
settling ponds and reduced pump pressures of
water to discharge points.
25
Environmental Problems

• Suspended Solids Silt
• Problem Solid matter in water
• Sources Nearly every process in mining. Surface
  drainage is the main contributor.
• Effects Reduced light penetration resulting in
  low bacterial activity. Abrasive effects on
  pipes, river beds and aquatic species. Silting
  and deposition causes visual impacts as well as
  reducing river volume, flooding and limiting boat
  navigation.

26
Environmental Problems

• Monitoring Sampling and Laboratory analysis, i.e
  filtering and weighing.
• Control (Source)
• Drainage ditches
• Vegetation on surface
• Reduction of surface runoff

• Control (Discharge)
• Filtering at processing plants, settling ponds
  and reduced pump pressures.
• The scale of silt deposited or washed into
  controlled waters depends on the volume of mine
  dewatering, processing, rain intensity,
  impervious surfaces, and drainage gradients.

27
Acid Mine Drainage
28
Acid Mine Drainage

• Acid Mine Drainage (A.M.D) is becoming a big
  problem with abandoned metalliferous mines.
• The E.A deal with A.M.D from abandoned mines.
  Wherever possible they attempt to get the former
  mine operator to deal with the environmental
  consequences of abandoning the mine. Where this
  cannot be achieved the E.A have to step in to
  protect the environment.
• The E.A are heavily involved with the clean-up of
  Cornwall old tin mines where the mine owners
  cant be traced.

29
Acid Mine Drainage

• Acid mine drainage is polluted water that
  normally contains high levels of iron, aluminum
  and sulphuric acid.
• The contaminated water is often an orange or
  yellowish-orange color, indicating high levels of
  iron and has the smell of rotten eggs (sulfate
  smell).
• Acid mine drainage comes from pyrite or iron
  sulfide, a mineral associated with coal mining.
  When pyrite is disturbed, as it is during coal
  mining or highway construction, it weathers and
  reacts with oxygen and water to cause high levels
  of iron, aluminum, and sulfate in runoff water

30
(No Transcript)
31
(No Transcript)
32
Acid Mine Drainage

• The ferrous ions that are produced from the
  pyrite, oxygen, and O2 can further oxidize and
  produce hydrated iron oxide (known as yellowboy)
  and more acidity.
• The acid lowers the pH of the water making it
  difficult to support aquatic life and treat for
  drinking water.
• The iron oxide forms a orange, or red coating to
  form on the bottom of the watercourse, which
  furthers the difficulty to support aquatic life.

33
Preventing A.M.D

• The best practice for preventing A.M.D is to
  concentrate on the source. Some options available
  are
• Sulphide removal from dump
• Bioleaching
• Physical removal
• Alkalinity enhancement of groundwater
• Surface lime applications
• Alkaline trenches
• Control of water infiltration
• Diversion ditching
• Recontouring of dump surface
• Suitable impervious linings

34
Preventing A.M.D

• Control of oxygen to dump
• Capping dump surface
• Flooding
• Reduction of bacterial populations
• Bacterial applications
• Phosphate rock additions
• The cheapest and most common method of preventing
  A.M.D is to flood the tailings, dump or source of
  pyrite.

35
Diffuse and Point SourcePollution
36
Point Source

• A point source for effluent discharge is a pipe
  or specific discharge location from the waste
  generator.
• This is mainly a pipe that has sophisticated
  equipment to monitor specific parameters of the
  effluent that is being released into controlled
  waters.

37
Point Source

• The monitoring equipment will be a requirement of
  any I.P.P.C Licence to make sure the effluent is
  within discharge consents.
• A point source can easily be managed and the E.A
  or other governing body can take sample easily
  and accurately.
• Point sources give high pollution concentrations
  in the immediate discharge to controlled water,
  opposed to a diffuse source that can filter the
  pollution over a wider discharge area.

38
Diffuse Source

• Diffuse water pollution can arise from many
  sources. These are generally dispersed and
  diverse in nature.
• Individually the sources may be small, but their
  collective impact can be damaging.
• An example of a diffuse source in mining is
  A.M.D. The E.A treats them as diffuse pollution
  because of the potential for widespread impacts
  and the uncertainties associated with predicting
  where and when they may occur.

39
Diffuse Source

• Diffuse pollution can be derived from current and
  past land use in both agricultural and urban
  environments.
• It can also include atmospheric deposition.
• Diffuse water pollution is mainly related to the
  way we use and manage land and soil. It can
  affect rivers, lakes, coastal waters and
  groundwaters.

40
Diffuse Source

• Groundwaters are vulnerable from, and affected
  by, leaching of pollutants from the land surface
  and from areas of contaminated land, while
  surface waters are affected by rainfall that
  washes over and off the land (run-off).
• Rivers can also be influenced by the contribution
  to their flow that comes through springs and
  seepages from groundwater. Where the groundwater
  connection with surface waters is high, pollution
  can pass from one to affect the other.
• Run-off has increased as agriculture has
  intensified and as we have built more roads and
  houses, particularly where we have degraded the
  natural permeability of the landscape and reduced
  its capacity to retain water.

41
(No Transcript)
42
Diffuse and Point

• Modern mines in developed countries have only
  point sources due to restriction on the
  collection of surface water and conditioning.
• Poorly managed mines, which are generally found
  in poor counties generally have high volume point
  sources and diffuse sources.

43
Next WeekNO LECTURE!