A Protocol and Standard for Mine Ventilation Studies

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A Protocol and Standard forMine Ventilation
Studies

• Rick Brake
• Mine Ventilation Australia

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Populations USA 304 million Aust 22 million
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Why do we need a generally-accepted protocol
and standard?

• Major mining houses are developing internal stds
• World bank others developing own stds
• Legal implications of duty of carean industry
  accepted standard helps demonstrate care
• Building codes and national or international stds
• Prosecution policies of regulators
• Part of quality assurance principles
• Example internationalisation of ore reserves
  codes
• Increasing use of peer review
• Will benefit stakeholders

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Safety and Health

• Ventilation planning for the Westray mine did
  not address the requirements for a comprehensive
  system of fresh-air circulation and methane
  removal. The plan on which the ventilation was
  based was merely a brief outline in a feasibility
  study. A comprehensive engineering study by
  competent ventilation experts was not completed
  and documented before approvals were requested
• The Westray Story-A Predictable Path to Disaster,
  Report of the Westray Mine Public Enquiry into
  the death of 26 miners on 9 May 1992 Province of
  Nova Scotia, Justice K P Richard, Commissioner

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Peer Review

• ... an assessment of an opinion or study
  conducted by a person or persons of similar
  expertise to the author
• Typically involves an additional cost of 2 to 5
  of the study cost
• Peer review has stood the test of time with
  regard to technical publications logical to
  extend it to study processes

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Peer Review (2)

• Two types now in use in Australia
• Internal peer review within a consulting firm
• Independent peer review organised by client
• By a third party
• Specialist panel within the clients organisation
• For effective peer review, reviewers need
• To be technical competent (i.e. peers)
• Have no stake in the outcome of the review
  (unbiassed)
• Must be formal, rigorous and carefully documented
  else can become unfair and witch hunt

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Hold and Review

• In a major study, there are many technical teams
• Battery limits separate the teams
• A key issue is to ensure disparate technical
  teams arent operating under conflicting design
  criteria or assumptions
• Example rock mechanic team has resolved that
  maximum unsupported vertical airway size can only
  be 3.5 m, but ventilation team is assuming 4.5 m
  is acceptable
• Intention is to avoid rework, and additional
  costs and delays that go with it

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Hold and Review (2)

• Hold Review mtgs are formal mtgs at which key
  representatives from each technical discipline
  listen to each others presentations on the
  status of their design
• Purpose
• What incompatibilities exist in the designs?
• What duplication exists?
• What has fallen between the cracks (no-one is
  addressing)?
• What new opportunities for improvement exist in
  the design?

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E-rooms

• Studies often produce hundreds of interim file
  notes from large number of individuals teams
• Many have to be circulated for review
• Significant issue is documents being lost,
  misfiled, or delayed to the point of adverse
  effect
• E-rooms
• Allow documents to be shared for review
  simultaneously
• Provide for formal document control ensuring
  those required to provide feedback do so
• Allow documents too large for email to be shared

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Implications of Duty of Care

• Upside is that
• Provides freedom from prescription so that
  innovation is possible with flexible solutions
• Captures risks not noted in regulations incl new
  risks
• Encourages greater ownership of risk mment by
  industry
• Downside is that standards may become worse
• Duty of Care is often linked to the as low as
  reasonably achievable (ALARA) i.e. ALARA
  defines the standard of the duty of care
• Meeting minimum statutory requirements is not
  sufficient
• How can duty of care be established, and
  demonstrated / audited?

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Duty of Care Clients perspective

• Clients need to establish industry good
  practice?
• This changes over time, so major new studies need
  to re-establish what is ALARA?
• Importance of bench-marking
• Importance of risk assessment
• Importance of internal standards for consistency
• Importance of internal audit processes

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Duty of Care Consultants perspective

• Many issues are similar to the Clients
  perspective
• Consultants developing own internal standards
• Dilemma when client does not want to meet duty
  of care as consultant believes it to be
• Either withdraw from engagement, or use risk
  assessment process (with client) to demonstrate
  duty of care and ALARA is still being met

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Duty of Care Regulators perspective (Compliance
Prosecution Policy) (1)

• Sufficiency of safety management plans
• Implementation of safety management plans
• Training of personnel in terms of
• Content of the plans
• Accreditation to be competent in the plans
• Understanding of implication of content of the
  plans

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Duty of Care Regulators perspective (Compliance
Prosecution Policy) (2)

• Communications in the organisation in terms of
• Internal comms within between depts
  individuals
• External comms between company other orgs
• Retention of knowledge base (corporate memory)
• Previous incidents of this type
• Risk assessment process esp controls in place
• Good practice across the industry
• What other options were considered, if any
• Audit systems in place

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Implications for ventilation studies

• Must include examination of industry good
  practice
• Must demonstrate that alternative solutions were
  examined, and reasons for rejection (esp if lower
  risk)
• Must be linked to risk assessment at some stage

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Management of a Technical Study (3)

• Irrespective of level of study, solution
  presented must be tangible, i.e. design presented
  can be implemented within existing knowledge,
  technology experience
• Opportunities for improvement are listed
• Study is risk assessed before going to next phase
  of study

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Management of a Technical Study (5)

• In practice, it is difficult or impossible to
  deliver study on time, to the required standard,
  meeting the fit for purpose objectives and
  within budget
• Consequences of study not meeting required
  standard, or not meeting fit for purpose could
  be very damaging
• Study manager needs to have sufficient clout to
  ensure these two key objectives are met, despite
  organisational push on the other two (time cost)

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Key issues for multi-disciplinary team

• Purpose/objectives, deliverables level of
  confidence of study must be identified agreed
• Study needs experienced study manager
• Battery limits for various sub-teams/disciplines
  must be set out and agreed
• List of overall design specs must be owned by
  study manager and is a controlled document
• Cost time estimates must be realistic good
  controls in place
• Regular formal and informal communications
• Formal Hold and Review meetings

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Scope of a mine ventilation study

• Review of ventilation hazards (gases, dusts,
  radon, heat, spon comb, etc) management
  controls
• Primary ventilation network at all key milestones
  in the mine life (volume distribution of air)
• Secondary/auxiliary ventilation design
• Review of egress entrapment provisions over
  life
• Develop ventilation management plan covering day
  to day operation management of the vent system
  including TARPs, SWPs and SOPs
• Formal risk assessments for normal activities
  abnormal activities (e.g. power failure, fire,
  etc)

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Special problems of brownfields sites

• Competition and conflict for limited plant
  equipment (airflows, intakes/returns, etc)
• Existing mine is essential for current production
• Future mine is essential for longer-term prod
• Inevitable human resource conflicts and
  personality issues between the management teams
• Problems of adopting new good practice HR or
  safety or operating practices whilst leaving
  existing ones alone
• Overall higher complexity of brownfields site
  with numerous interactions well into life of
  project

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Required inputs for a ventilation study (1)

• Dust, radon and/or methane or other airborne
  gaseous, fume or particulate contaminants or
  asphyxiants (e.g. nitrogen)
• Gas contents of orebody/coal seam and adjacent
  strata issues of gas drainage
• Spontaneous combustion potential
• Outburst potential
• Water inundation (flooding) potential
• Dust audits, silica (or other contaminant)
  contents of strata
• Production, development, diamond drilling,
  raiseboring (or other vertical development) and
  production drilling schedules
• Other important schedules or deadlines (e.g.
  construction schedules)
• Mining methods, layouts, mine design, etc

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Required inputs for a ventilation study (2)

• Manpower schedule, by job type and location for
  both production and construction phases
• Major mobile equipment schedules, especially
  diesel equipment (maximum kW rating, dimensions,
  speed loaded and unloaded, up and down ramp,
  tonnes moved)
• Mode of operation of diesel equipment (where
  travel, when, truck/loader combinations)
• Diesel fuel usage, average and maximum per shift
• Fixed electrical plant and efficiencies
• Any special areas requiring filtered air or
  special ventilation (e.g. control rooms,
  cribrooms, offices, ventilation at crusher jaws,
  transfer points on belts, tipping points)
• Coal, ore, mullock/waste or other materials
  handling flowcharts

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Required inputs for a ventilation study (3)

• Humidity limits for ore/waste including transfer
  points
• Humidity limits for ground control/rock strata
• Backfill system and operation, type of fill,
  method of placement
• Locations of fuel and oil storage, refuelling,
  other major stores, combustible material, etc
• Parking arrangements
• Special fire fighting standards
• Special egress or entrapment standards
• Any maintenance arrangements impacting on egress
  (outages, inspections, etc)
• Minimum medical/physical requirements for
  continuing employment or for visitors

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Required inputs for a ventilation study (4)

• Blasting arrangements development and
  production, bins, chutes, etc, including
  frequency of blasting development and production
• Re-entry times after blasting etc
• ANFO and other explosives consumption rates
  development and production
• Cement usages and consumption rates
• Oxidation rates (to SO2 and/or CO2)
• Working in heat protocols
• Other special ventilation-related hazard
  protocols
• Internal corporate ventilation/workplace
  environment standards for each job type (i.e.
  typical ventilation arrangements)
• Statutory (legislative) requirements
• Internal (company or mine) generic standards,
  hazard management plans, etc

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Required inputs for a ventilation study (5)

• Any noise criteria (impacting on noise insulation
  or siting of fans etc)
• Any sources of dust, e.g. due to cutting,
  loading, etc
• Dust controls (e.g. sprays) at drawpoints,
  tipples, conveyors, roads
• Other sources of heat
• Surface climate (WB, DB, BP) by hour for minimum
  of six years
• Surface elevation above sea level
• Depth of mining operations
• Near-surface virgin rock temperature and
  geothermal gradient
• Rock thermal conductivity, thermal capacity,
  diffusivity, density
• Maximum heading lengths for auxiliary
  development, development heights and widths
• Method of auxiliary ventilation, type and size of
  ducts, leakage factors
• Any existing ventilation circuits, fans
  (including fan curves), controls etc

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Required inputs for a ventilation study (6)

• Any existing cooling devices
• Usage and policy on air-conditioned cabins in
  mobile equipment and fixed plant
• Mining (especially horizontal and vertical
  development) and ventilation (fan, controls,
  ducting) costs
• Friction (k) factors and shock losses used or
  measured in the operation
• Any surface considerations (dust from quarrying
  etc, prevailing winds, grass/bush fires, nearby
  plant)
• Surface environmental limits on fans and shafts
  noise, dust, water, smell, visual amenity
• Shaft, raise and other major airway resistances
  and last time measured
• Standards in regard to allowable pressures on
  ventilation doors (airlocks) or other ventilation
  controls

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Required inputs for a ventilation study (7)

• Ventilation or isolation of caved regions or
  goafs leakage and pressure balancing
• Network analysis and validation (comparing to
  measured data)
• Multi-level tipping controls or protocols
• Ground/fissure water in mine (amount, location,
  temperature (if very hot))
• Location of shafts, fresh and return air raises,
  distances apart (determines typical auxiliary
  ventilation line configurations and lengths)
• Wetness of shafts. If wet, potential for water
  corrosion or erosion on fans. Potential for the
  shaft to be subject to erosion or sloughing or
  water plugging
• Natural ventilation pressures seasonal changes
  impacts of refrigeration on natural ventilation
  pressures

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Required inputs for a ventilation study (8)

• Network simulation program used
• Other computer programs in use or required to be
  used
• Data on ventilation monitoring (e.g. strata
  gases, diesel exhausts, airflows, on-line
  monitoring)
• Recent or relevant ventilation or feasibility
  studies
• Any other safety aspects that need to be
  considered
• Any recent ventilation audits completed
• Any concerns from the operators or planners about
  current or future ventilation problems
• Any telemetering, remote monitoring or remote
  operation/control requirements

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Characteristics of phased approach to studies

• An increase in knowledge and confidence
• A reduction in risk to acceptable limits (risk is
  never eliminated completely)
• Significant increases in expenditure on project
  evaluation (design, drilling, metallurgical
  testing, etc) for each stage
• An increase in allocation of resources and
  personnel to the project and study
• An increase in third party stakeholder
  involvement
• Escalating internal momentum and expectations
  making major changes in direction or cancellation
  of the project increasingly difficult

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Basic objective of phased approach to studies

• Screening projects so that excessive monies are
  not spent on projects that could have been
  rejected at a lower level of study.
• Ensuring that at a more detailed study stage, it
  is not possible to come up with credible options
  that should have been considered at an earlier
  phase, and which may then require a substantial
  amount of additional work to either adopt or
  eliminate
• Remove bias and make more sound investment
  decisions

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Required level of confidence for a ventilation
study

• Tendency in past to proceed very quickly to final
  feasibility study saving time and money
• Meant alternative approaches not properly
  considered
• Best possible outcome is sub-optimal design
• Worst possible outcome is complete failure
• Phased approach to studies gives lowest overall
  cost and fastest study time, in long run

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Phases of study (1)
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Phases of study (2)
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Phases of study (3)
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Phases of study (4)
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Summary and conclusions

• No national, international, or professional
  standards for mine ventilation studies at present
• Duty of Care and ALARA will push our profession
  towards being able to demonstrate consistency and
  quality that will meet peer review
• Some codification of the study process and
  deliverables is in our own interest, and that of
  our stakeholders (clients) as well as the Public
• Any standard is likely to develop over time, and
  may never be fully formalised