ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
The Mining Sector
Energy Efficiency Opportunities Assessment
In this module Educator’s Overview ...........................65
Teaching and Learning Resources Key Concepts .....................................66 Case Studies ......................................68
The Australian mining and mineral processing industry is an energy intensive sector spending over AUD $5.7billion and consuming 414,000 terajoules of energy in 2010/11. This is 11% of total Australian energy consumption.
Further Resources ..............................69
Tutorial and Assessment Options Class Options .....................................70 Worked Example - Petroleum Refinery ...71 Assessment Options ...........................73
See also Module Video Introduction
Energy already makes up 10-30% of total business costs in this sector, and energy efficiency is an immediate and effective way to reduce these energy input business costs. Graduates with knowledge of how to reduce energy input costs are in demand.
The College of Engineering and Computer Science and the Fenner School of Environment and Society,
Australian National University was commissioned to develop this educational resource by the Department of Industry.
The Australian National University, Canberra CRICOS Provider: 00120C ABN: 52 234 063 906
Attribution-Share Alike CC BY-SA
View Australian Licence Deed
View Australian Legal Code
Citation:
Smith, M., Stasinopoulos, P., Browne, C., Compston, P., (2014), ‘The Mining Sector: Energy Efficiency Opportunities Assessment’ in Energy Efficiency Resources for Undergraduate Engineers, Australian National University.
64
ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
The Mining Sector EEO Assessment
Educator’s Overview Intended learning outcomes
Class options
On successful completion of the requirements of this module, students will be able to:
Options for classroom activities are detailed in the Class Options section. These include:
LO1 Identify major areas of energy efficiency opportunity for the mining and mineral processing sector LO2 Analyse energy efficiency opportunities in the mining sector given relevant information and data LO3 Communicate technical and design innovations in the mining sector to enable greater energy efficiency improvements.
C1 Technology energy efficiency exercise C2 Mining sector energy efficiency exercise C3 Worked example energy-mass balance (EMB) workshop
Assessment options Options for assessment are detailed in the Assessment Options section. These include: A1 Technology assignment/question A2 Mining sector report/presentation A3 Worked example EMB presentation
Program pathways This module is suitable for: •
• • •
due to the size of the Australian mining industry, students from all sub-disciplines can find work experience in the mining sector 2nd-4th year engineering management and practice courses mining and metallurgy engineering management, design and practice courses environmental engineering
Engineers Australia competencies Successful undertaking of this module can be used to show achievement of Engineers Australia Stage 1 competencies. These are shown in the mapping below.
See the complete Educator’s Guide for further ideas on how to integrate this content into your course
Mapping of proposed activities to intended learning outcomes Class Options C1 LO1
✓
LO2
✓
LO3
C2
Assessment Options C3
A1
✓ ✓
✓
✓
✓
A2
Engineers Australia
A3
Competencies
✓
✓
1.6, 2.1
✓
✓
2.2, 2.3
✓
3.2, 3.4
✓
65
ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
The Mining Sector EEO Assessment
Key Concepts Overview The mining sector is a significant consumer of Australia’s energy demand. There are many opportunities to both reduce energy demand and improve productivity through incorporating energy efficiency measures across the sector. A formal Energy Efficiency Opportunities Assessment can identify and highlight energy efficiency opportunities.
Energy intensity trends The mining sector consumes 11% of Australia’s total energy consumption. The energy intensity of this sector has risen 70% over recent decades due largely to declining ore grades. This is in contrast to most other business sectors have improved their energy efficiency.
A key problem for the mining and minerals processing industry is that as ore grades decline, mining becomes more energy intensive through: • • • •
123
agriculture -17 -32
residential services manufacturing and construction
-86 -152 -160 -120 -80
12
transport -40
0
40
80
120 160
petajoules Changes in energy consumption 1989–90 to 2007–08. (Adapted from ABARE 2010)
This inverse relationship means that more energy and therefore cost is required to extract the same amount of valuable mineral. FINANCIAL AND ENERGY COST
mining
the increased volume of ore body needed to obtain the same unit of valuable minerals the increased amount of grinding and crushing required to separate out the valuable minerals the increased overburden to be removed to access ores deeper underground the increased depths of underground mining
future operations
present day
RELATIVE SIZE OF PARTICLES
On current trends, energy costs are likely to continue rising in Australia at approximately 6% per annum. Most mining companies operate in remote locations and rely on diesel fuel to power mining haul trucks and generators to run mining crushing and grinding mills, so embedding energy efficiency is a key part of reducing future energy demands.
As ore quality declines, energy requirements increase. (Adapted from CEEC 2014)
Energy efficiency is an opportunity for many savings across the sector, and many mining companies have already committed to shortand long-term targets.
66
ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
The Mining Sector EEO Assessment
Energy Efficiency Opportunities Assessment An initial step for identifying potential energy efficiency opportunities is conducting a sitewide energy-mass balance (EMB) to benchmark energy and material flows. From this baseline, the potential and cost of improving energy efficiency can be calculated.
Oil and gas sector Major areas for improving energy efficiency in the oil and gas sector are: • • •
• •
Level 1 Whole site
Level 2 Mine subsystem data and performance indicators
Level 3 Detailed energy analysis and modelling
Elements of a mine site EMB
(Adapted from Department of Industry 2010)
Mining and mineral processing Major areas for improving energy efficiency for the mining and mineral processing sector are: • • • • •
•
mineral ore body materials movement, such as removing overburden and hauling mineral ore air ventilation and conditioning for underground mining comminution (crushing and grinding) processes to extract minerals from ore bodies froth floatation and minerals separation common technology opportunities; for example, motors, pumps, fans, lighting, and compressed air systems improved thermal efficiency of onsite electricity generation; for example, investing in thermally efficient combined cycle gas electricity generation systems
•
reducing flaring, venting and leaks improving thermal energy efficiency of onsite energy generation for refineries improving and optimising the design of boiler and steam systems and gas compression equipment reducing common energy in offshore drilling rigs enhanced oil and gas extraction, including innovations in drilling techniques oil and gas pipeline transportation and refinement
Identifying EEOs As well as improving energy efficiency at existing sites, large energy efficiency savings can be achieved when designing and constructing new oil and gas development projects through embedding energy efficiency into the early design, procurement, and detailed design and construction phases of resource projects. Undertaking an EMB for existing and new developments is an important first step in identifying the potential savings at any given site.
References ABARE-BRS Report 10.08 (2010) End Use Intensity in the Australian Economy. Available at
http://adl.brs.gov.au/data/warehouse/ pe_abares99001743/ RR10.08_energy_intensity_REPORT.pdf Department Of Industry (2010) Energy Efficiency Opportunities: Energy-Mass-Balance. Version 1.0. Department Of Industry. Available at:
http://www.ret.gov.au/energy/Documents/ energyefficiencyopps/EMB%20Mining.pdf
Many mine sites have improved their energy efficiency in recent years. However, it is always possible to continuously improve tracking energy consumption trends.
67
The Mining Sector EEO Assessment
ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
Case Studies This is a list of selected case studies that demonstrate embedding energy efficiency into the management of their operations. Xstrata Coal Xstrata Coal has undertaken energy efficiency opportunity assessments as a member of the Commonwealth Government’s Energy Efficiency Opportunities program. This resulted in 47 cost-effective projects being identified, many of which were acted upon straight away achieving energy savings of 13,686 GJ per annum. Anglo Platinum - Mogelkwena Operation Anglo, working with the CRC ORE, implemented resource characterisation, smart blasting and ore sorting to achieve a 2-2.5 fold increase in ore body concentration for the feed into “grinding” mills, leading to significant energy savings. Barrick Gold Corporation Barrick Gold Corporation undertook extensive analysis of energy efficiency performance at their mining sites. This enabled the achievement of up to 20% net energy efficiency improvement in its grinding mills in four of its operations, which it reviewed. Available at: http://www.ret.gov.au/energy/ documents/energyefficiencyopps/industry/ improving-ee-barrickgrindingcircuits.pdf
Copper - Molybdenum A 2013 study of the Huckleberry coppermolybdenum mine in Canada has shown that if the mine invested in the following energy efficient grinding equipment it would achieve significant energy savings. High pressure grinding rolls (HPGR) - ball mill circuit achieved a 21% reduction in energy consumption. At a grind of 80% passing 75 μm, the HPGR stirred mill circuit showed a 34% reduction in energy compared to the base case. This recent study found that the energy reduction for the new comminution circuit using HPGR systems significantly improved the economics of the comminution circuit.
This study was awarded the Coalition of EcoEfficient Coalition’s Medal for 2013 Thiess Australia Mining Business Unit Thesis has undertaken energy efficiency opportunity assessments identifying projects which could cut energy usage by 150,800 GJ/annum, including 3.9 million litres of diesel fuel, saving $3.7 million with less than a two year return on investment. Vale - Materials Movement US mining giant Vale is also replacing trucks at some of its mines with in-pit crushers and conveyors. In its largest Brazilian iron ore mines, Vale SA (VALE5) is replacing trucks with 23 miles of conveyor belts and a new railway line to cut materials movement related energy costs by 77%. BHP Billiton - Materials Movement BHP Billiton has found that technological advances in In-Pit Crushers and Conveyor technology now offer them the potential to achieve a step change in both labour and energy productivity in materials movement in open cut mines. ExxonMobil - Oil and Gas ExxonMobil launched its Global Energy Management System (GEMS) in 2002, which identified ways to improve efficiency by 15-20%. In 2006 energy costs were reduced by close to US$750 million and its CO2 emissions by about 8 million tonnes. British Petroleum - Oil and Gas BP has cut its own operational emissions of CO2 by 10% through investing in both energy efficiency and renewable energy. Chevron - Oil and Gas Chevron has reduced flaring and venting by 12% since 2007. Since 1992, Chevron has increased the energy efficiency of their global operations by 34%.
68
The Mining Sector EEO Assessment
ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
Further Resources These resources are useful for further exploration of energy efficiency in the mining sector.
Case study resources
ClimateWorks Australia and Department of Industry (2012) Industrial Energy Efficiency Data Analysis – The Mining Sector
Available at:
http://www.climateworksaustralia.com/ publications.html
These resources are general sources of information about energy efficiency in the mining sector:
Department of Industry (2012) Energy Efficiency Exchange – Mining Sector – Energy Efficiency Opportunities by Dr Michael Smith (ANU) and Adjunct Professor Alan Pears (RMIT)
Available at:
http://eex.gov.au/industry-sectors/mining/
Department of Industry, Energy Efficiency Exchange – Mining Available at:
http://eex.gov.au/industry-sectors/mining/
Department of Industry (2012) Energy Efficiency Exchange – Mining and Mineral Processing Technologies – Energy Efficiency Opportunities by Dr Michael Smith (ANU) and Adjunct Professor Alan Pears (RMIT)
Available at:
https://eex.govspace.gov.au/technologies/mineralprocessing/ ClimateWorks Australia and Department of Industry (2012) Industrial Energy Efficiency Data Analysis – The Mining Sector
Available at:
http://www.climateworksaustralia.com/ publications.html Coalition for Eco-Efficient Comminution (CEEC) Web Portal.
Available at: http://www.ceecthefuture.org/
Notes: Features over 70 relevant and current peer reviewed “Key Papers”, “Technical” and “Conference” papers
Mining and mineral processing
Department of Industry (2011) Analyses of Diesel Use for Mine Haul and Transport Operations 2011. Department of Industry.
Available at: http://www.ret.gov.au/energy/ Documents/energyefficiencyopps/res-material/ Analysis-of-Diesel-Use.pdf
This report provides examples of comprehensive analyses of diesel use in mining operations used by Fortescue Metals Group Ltd, Downer EDI Mining Pty Ltd and Leighton Contractors Pty Limited. Queensland Resources Council (2011) Earth Hour Report – Case Studies. QRC.
Available at: http://www.qrc.org.au/_dbase_upl/ Earth%20Hour%20(final).pdf Australian Greenhouse Office and the Minerals Council of Australia (2002) Energy Efficiency and Greenhouse Gas Reduction Best Practice Manual Mining. Available at: http://www.ret.gov.au/ resources/documents/lpsdp/bpemenergy.pdf
Oil and gas sector case studies IPIECA (2013) Energy Efficiency and Greenhouse Gas Compendium – Web Portal.
Available at: http://www.ipieca.org/energyefficiency
Most of the 15 sub-sections of this online web portal have up to date industry case studies featured.
69
ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
The Mining Sector EEO Assessment
Class Options These activities are suggested for small-group activities, such as tutorials or workshops. Elements could also be incorporated into lectures. Each class option would be suitable for a 2hour session, with an opportunity to reduce to a 1-hour session by providing preparatory material in advance. These class options are mapped to the module learning outcomes in the Educator’s Overview.
C1
Technology EE exercise
Activity type Group or individual exercise Resources Smith, M. and Pears, A (2012) Energy Efficiency Exchange. Mining Energy Efficiency Opportunities Available at: http://www.eex.gov.au/mining Smith, M (2014) Energy Efficiency Exchange, Mineral Processing EEOs Available at:
http://eex.gov.au/technologies/mineral-processing/ The IPIECA’s comprehensive online compendium of EEOs in the oil and gas sector. Available at:
http://www.ipieca.org/energyefficiency
Activity In groups, give each group a technology and access to the resources: • • • • •
materials movement ore sorting comminution – crushing and grinding froth floatation, drying, ventilation and airconditioning oil and gas extraction and transportation
Ask students to brainstorm and shortlist ideas for energy efficiency opportunities in their technology. Groups should prepare a short presentation outlining these opportunities. The groups should then compare, contrast and look for connections between their technologies. Students could read the resources ahead of time, and use the session to workshop and refine their presentation. Extension This activity could be linked to a small assignment or homework.
C2
Mining sector EE exercise
Activity type Group or individual exercise Resources ClimateWorks Australia and Department of Industry (2012) Industrial Energy Efficiency Data Analysis – The Mining Sector Available at: http:// www.climateworksaustralia.com/publications.html
Activity Divide case studies between groups or student, and give students the ClimateWorks resource. Give each group a technology: • • • • •
underground gold and copper mines open cut iron ore mines coal mining – open cut coal mining – underground oil and gas extraction and transportation
Ask students to brainstorm and shortlist ideas for energy efficiency opportunities in their technology. Groups should prepare a short presentation outlining these opportunities. The groups should then compare, contrast and look for connections between their technologies.
C3
Worked example EMB exercise
Activity type Group or individual exercise Resources Worked example from this module Activity Ask students to attempt the worked example and extension question, and then check their ideas with their peers and the worked solutions. Students could attempt the analysis individually ahead of time, and use the session to workshop and refine their solutions or share insights between groups. Extension Groups should share their worked solutions so that the entire class has access to their ideas. Marks could be awarded for clear answers with helpful study comments.
70
ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
The Mining Sector EEO Assessment
Worked Example - Petroleum Refinery This worked example is a qualitative analysis.
Hint
Scenario and question
Take an approach as outlined in the Energy Efficiency Opportunities in Commonly Used Technologies module:
Petroleum refining plants are usually very complex integrated systems that separate and transform crude oil into a wide range of products that include transportation fuels, lubricants, and residual fuel oils. In refineries, crude oil is separated in various fractions based on boiling point. This is accomplished by fractional distillation of the crude oil. Refineries use energy primarily in boilers/co-generation systems to produce process steam to heat and separate various fractions of the petroleum or in cooling systems to help condense and cool separated petroleum products. Up to 30% of all energy used in petroleum refining is for steam generation. Overall, the main process steps using most of the energy in petroleum refining include crude distillation, hydro-treating, reforming, vacuum distillation, and catalytic cracking. Significant amounts of energy can be saved through optimising heat transfer and waste heat recovery in the design and operation of petroleum refineries.
Q1 Develop a strategy for identifying energy efficiency opportunities at this site.
• • •
reduce demand and unnecessary usage optimise the operation of existing technologies upgrading and investing in more energy efficient technologies
Useful resources On reducing demand See Worrell, E. et al (2005) Energy Efficiency Savings in the Petroleum Refining. US EPA and the LBNL. Available at: http://ies.lbl. gov/iespubs/ energystar/petroleumrefineries.pdf
On minimising waste heat For more information, see DRET (2014) Energy Efficiency Exchange Technical Pages Available at:
http://eex.gov.au/technologies/process-heatingand-steam-systems/ Worrell, E. et al (2005) Energy Efficiency Savings in the Petroleum Refining. US EPA & LBN.
Available at: http://ies.lbl.gov/iespubs/energystar/ petroleumrefineries.pdf
On optimising operation For more information: DRET (2012) Energy Efficiency Exchange Technology Pages.
Available at:
http://eex.gov.au/technologies/
71
ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
The Mining Sector EEO Assessment
Waste Heat Recovery (maximising exergy) There are numerous waste heat and power recovery opportunities in petroleum refineries:
Solution or discussion points Reduce demand It is possible to reduce demand for energy and heat, in the first place. In petroleum refineries: •
•
•
make the core processes more energy efficient. Opportunities to reduce energy demand are to be found in the heating process and in the optimising energy use in the distillation column reduce sub-optimal waste heat losses or gains through effective pipe sizing, use of insulation and recovery of condensate in steam traps and its return to the boiler set feasible energy targets (pinch analysis) to optimise process integration and design across the entire refinery
Minimise waste heat losses Up to around 30% of all on-site energy use in petroleum refineries is used in the form of steam. Waste heat and exergy can be lost from radiation from the boiler and piping, exhaust flue gas heat losses, and from loss of steam: •
• • •
•
many processes involve high temperature and pressure. Heat exchangers should be used where possible in the refinery to recover heat from processes for use in the process flows.
•
recover power from pressure in the flue gas because of the elevated pressure used in a number of processes. Fluid catalytic crackers (FCCs) provide the major opportunity to recover power in petroleum refineries. Power can be recovered from other equipment operated at elevated pressures such as hydrocrackers.
•
collecting condensate with steam traps and recovering flash steam
•
recover steam from “bleed” and heat from flue gases. This can be used, for instance to preheat “feed” water into boilers and thus save significant amounts of energy.
Reducing internal quality energy losses Maximising exergy by reducing irreversibilities. There are many technologies used commonly through petroleum refineries which consume significant amounts of energy.
through insulation and correct sizing of the boiler and piping, reducing standby losses, and reducing exhaust flue gas through better process control install the boiler system as close as possible to the point of use, minimising pipe heat loss check for leaks and repair them immediately improve water treatment and control of total dissolved solids, minimising blowdown and the loss of heated water from boiler systems
•
•
motor systems use up to 80% of all electricity in a refinery, driving pumping and fan systems, air compressors, and other applications. lighting uses around 3-5% of total electricity usage. It is possible to reduce energy waste by optimising or upgrading these technologies
Typically, electricity is significantly more expensive than fuel, so saving electricity can deliver disproportionately large costs.
Indicative effectiveness of energy efficiency measures. Measure
Fuel Saved
Payback Period
Co-benefits
Improved insulation
3-13%
1-2yrs
-
Improved steam traps
-
-
Greater reliability
Steam trap maintenance
10-15%
0.5-1yrs
-
Steam trap monitoring
5%
1-2yrs
-
Leak repair
3-5%
0.4-1yrs
Reduced requirement for major repairs
Flash steam recovery
Condensate Return Condensate return alone
89%
Unknown
Reduced water treatment costs
10%
1.1-1.6yrs
Reduced water treatment costs
72
ENERGY EFFICIENCY RESOURCES FOR UNDERGRADUATE ENGINEERS
The Mining Sector EEO Assessment
Assessment Options A1
Technology assignment
A2
Case study presentation
Suggested completion Individually, or in groups of 4-6 students
Suggested completion Groups of 2-5 students
Task Prepare a report detailing aspects of a technology in the mining sector, using an Energy Efficiency Opportunities Assessment.
Task Prepare a presentation detailing the energy flows of a case study, and present an EMB of the scenario during the benchmarking phase, and suggested opportunities for improvement.
Groups could examine a hypothetical scenario, or could extend and research one of the examples in the Case Studies section. The assignment could act as research for ‘management’, and could answer some or all of the following: • • • •
• •
what is the business case for investing in energy efficiency design opportunities? what are the major areas of energy efficiency design phase opportunities in new projects? what are the major areas of energy efficiency opportunities in the procurement phase? which opportunities are likely to achieve the fastest return on investment? Which would yield the largest energy savings? which areas of energy efficiency opportunity should management invest in? to support your argument, provide examples or case studies of companies in that sector who are implementing these energy efficiency opportunities
Groups should take a whole-of-system perspective when undertaking their analysis. Resources Use the EMB module as background information if required. An example of an EMB in the mining sector is available at: Department of Industry (2010) Energy Efficiency Opportunities: Energy-Mass-Balance. Version 1.0. Department of Industry
http://www.ret.gov.au/energy/Documents/ energyefficiencyopps/EMB%20Mining.pdf
A3
Worked example presentation
Suggested completion Individually, or in groups of 2-3 students Task Undertake the analysis presented in the worked example. Prepare an EMB describing the main energy flows in the worked example. Present the EMB of during the benchmarking phase, and then a second EMB highlighting the opportunities for improvement.
73
