Mine Waste Description and Management in Chile

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Mine Waste Description and Management in Chile
Jacques Wiertz Consultor Ambiental
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What do we produce in Chile ?
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What is a waste ?

• Waste is an unwanted or undesired material or
  substance. It is also referred to as rubbish,
  trash, garbage, or junk (http//en.wikipedia.org)
• Waste any materials unused and rejected as
  worthless or unwanted
• Negative value can not be capitalized
• Minimize the cost of management and disposal
  reducing any environmental and health risk

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Chile, a mining country

• Long tradition in mining silver, gold, nitrate,
  iron, coal and mainly copper
• Boom and decline of nitrate at the beginning of
  the XX Century
• More than 100 years of large scale copper
  extraction at El Teniente Mine, biggest
  underground mine in the world
• Important growth of mining in the 90s and again
  more recently
• This is reflected by the large amounts of mining
  waste all along the country

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Chilean Copper Production
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Copper production
Mining extraction (underground or open pit)
Mining extraction
Mineral processing
Crushing and Milling
W A S T E S
Extractive Metallurgy
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Chile a mine waste producer

• Copper production 2006 5.36 106 t
• Refined copper more than 2.5 106 t
• Daily waste generation
• 1.6 106 t of overburden and waste rocks
• 650,000 t taillings
• 10,000 t SO2
• 12,000 t slags
• ........

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Waste production

• Estimate of wastes generated for each ton of
  Copper produced (sulfide processes)
• Cu in ore about 1.0 (mean ore grade decrease
  about 0.1 every 10 years)
• For 1 ton of ore, about 2 t of waste rocks must
  be removed ratio increase with pit depth
• Concentration plant recovery is about 90 while
  smelter plant recovery si about 95
• Concentrate composition about 30Cu, 30S and
  30S
• In smelter plants, Fe is eliminated in slag
  (FeO.SiO2) and S as SO2
• SO2 captured is transformed to H2SO4

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Waste production
Waste rocks and low grade 234 t
Copper ore 117 t
Tailings 113 t
Copper concentrate 3.5 t
Slags 2.6 t
SO2 2.1 t 95 captured
Copper anode 1.01 t
I ton Cu cathode
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Metals in use
Mineral resources
Mineral reserves
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Equilibrium Economical, Social, environmental
Criteria for assessment on mineral resources

• Resource use efficiency

100

• Energy use efficiency

Environmental sustainability

• Wastes
• Impact minimization

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Environmental aspect Environmental impact
Air
Source (emission)
Receptor (exposition)
Water
Soil
Transport medium (dispersion)
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Waste management Mine life cycle
Ore characterization Base line information Waste
rock charact.
Impact Assessment Tailing and dump
design Environmental design
Monitoring EIA validation Continuous waste
characterization
Mine closure plan Mine waste rehabilitation
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Environmental regulations

• Environmental Impact Assessment System EIA and
  DIA
• Quality standards
• Primary standards health
• Secondary standards environment and ecosystems
• Emission standards
• Decontamination plans (PM10, SO2)
• Specific regulations hazardous wastes

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Massive mine wastes

• 4 types of mine wastes are excluded from the
  hazardous waste regulation
• Waste rocks and low grade ores
• Tailings
• Leached ores
• Smelter slags
• Environmental and health authorities may ask for
  guarantees of safety SPLP is the applicable
  test

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Waste rock dumps

• Visual impact
• Dust emissions
• Acid drainage
• Usually considered as innocuous

• Poor characterization
• Heterogeneous
• Difficult to sample
• Assessment before operation and for closure

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Tailings

• Very large structures
• Potential instability
• Potential infiltrations
• Potential acid drainage
• High sulphate in water

• Usually considered homogeneous
• Difficult to sample
• Stability is the main concern
• High effluent flow

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Leached ores

• Acid solution content
• Low neutralization potential
• Potential acid drainage

• Not supposed to produced any drainage
• Use of covers for closure
• Long term monitoring

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Slags

• Usually very stable depends on cooling rate
• High metal content
• Potential use for toxic compounds disposal

• Difficult to sample and characterize
• Potential use as secondary ressources

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Problems and challenges

• Before operation
• Impact assessment emission factors and
  environmental modeling require validation
• Environmental base line studies
• Sampling procedure
• Material characterization laboratory quality
  control
• Environmental design need to traduce the
  environmental data in input for the operation
  design

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Problems and challenges

• During operation
• Monitoring not only to compliance with current
  regulation but for impact assessment validation
• Online waste characterization information should
  be used for operation and to consolidate mine
  closure plan
• Integrate impact minimization reduce all the
  impacts in a mine cycle perspective (Life Cycle
  Assessment methodology)

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Problems and challenges

• Closure
• Complete information of the operation is required
• Waste deposits are difficult to sample
• Long term perspective need to assess the return
  period of extreme events
• Wastes of the present may turn to resources for
  the future

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Research needs and oportunities

• Recovery of subproducts and mine waste valuation
• Integral arsenic management reduction of arsenic
  atmospheric emissions and safe disposal of
  arsenic residues
• Sulphate removal from effluents
• Reduction of dust emission during transport and
  disposal of wastes
• Online waste characterization techniques and
  methodologies
• Life cycle assessment of mine wastes