Themes and Impact Opportunities
The areas where the alumina industry can contribute to global Sustainability have been classified according to four Themes: Energy, Residue, Water, Emissions. Aspects that have the potential for transformative innovation are identified as Impact Opportunities within these Themes. The SDGs applicable to each Theme are shown. Alternative production routes to the Bayer process are also considered in the Pathways to 2050.
Action Plan Summary
Theme |
Impact Opportunities |
2050 Goals |
Enablers |
Energy |
1. Shift to green energy for heat and electricity generation | Global alumina production 100% carbon-neutral |
|
| 2. Continuous improvement in Bayer process efficiency | Global average Bayer process energy consumption reduced by 2 GJ/tA from 2020 base |
|
|
Residue |
3. Eliminate the need for long-term bauxite residue storage | Zero new long-term bauxite residue storage |
|
| 4. Ensure safety and sustainability of stored residue | Zero leakage and mechanical failures of residue storage impoundments |
|
|
Water |
5. Eliminate import from high quality water sources | Zero import of high quality water |
|
Emissions
|
6. Eliminate emissions to soil, water and air | Emissions to soil, water and air reduced to sustainable levels acceptable to all stakeholders |
|
Theme: Energy
Applicable SDGs : 7, 9, 12, 13, 17
The 2050 Energy Goals for alumina production are:
- Global average Bayer process energy consumption reduced by 2 GJ/tA from 2020 base
- Global alumina production 100% carbon neutral
Impact Opportunity 1. Increase proportion of renewable energy or innovative energy technologies used in production
Potential renewable energy sources include:
- hydro-electric
- hydrogen and other alternative fuels
- solar photovoltaic
- solar thermal
- wind turbine
- tidal
- geothermal
- nuclear energy
- CCUS.
Industrial hubs will be an enabler.
Barriers to implementation:
- continuity of supply and especially storage (for solar, wind)
- under-developed alternative technologies for some unit operations
- forced obsolescence of existing infrastructure
- very high capital investment, probable high Opex compared to fossil fuels
- public and government acceptance (especially for nuclear)
- risk aversion.
Enablers and Opportunities:
Energy conversion and storage options
- heat reservoirs (molten salt)
- batteries
- hydrogen (via water electrolysis)
- methane (via Sabatier process) – liquefied or compressed and stored in deep wells?
Steam for digestion
- solar thermal to molten salt directly for jacketed tube digestion
- electrically powered boilers
- solar thermal to steam
- methanation with heat recovery.
Electrical power
- direct production using known renewable technologies
- load levelling, day/night cycles and weather: same as for Energy storage.
Calcination
- super-heated steam (may affect alumina quality)
- electrically heated air (indirect)
- plasma spout fluidised bed
- hydrogen burner
- methane (minimal change required).
Impact Opportunity 2. Continuous improvement in Bayer process efficiency
Enablers and Opportunities:
- Digestion (and evaporation)
Compression of flash tank steam for pre-heating bauxite slurry.
Slurry heating by indirect high temperature process such as electrical induction. - Calcination
Non-combustion heating from renewable sources, e.g., direct solar, microwave.
Steam compression and heat recovery.
No dilution by combustion gas. - Separation liquid/solids
Two stages of press filtration: one replacing the settlers (such as Diastar technology).
The second stage to be similar to that currently used for residue storage. - Liquor Productivity
Improved precipitation yield, e.g., by ground fine hydrate recycle, impurities removal. - Impurities removal
New side-stream processes for organics removal. - Soda consumption
Elimination of silica from bauxite by bio-chemical and/or other means. - Bauxite quality and beneficiation
Improve bauxite quality to improve process efficiency, reduce residue generation and raw material use.
Theme: Residue
Applicable SDGs : 9, 12, 15, 17
The 2050 Residue Goals for alumina production are:
- Zero new long-term bauxite residue storage
- Zero leakage and mechanical failures of legacy residue storage impoundments
Impact Opportunity 3. Reduce residue salinity and alkalinity
Prioritised SDGs: 9, 12, 15
Enablers:
- Bauxite pre-treatment (reduction of kaolinite content)
- Chemical additive to modify bauxite and/or residue properties
- Physical separation (hydrocyclone)
- Reduced DSP formation
- Improved Low Temperature Digestion Process (ILTD)
- Lime causticisation in pre-desilication
- Neutralisation by seawater, CO2, SO2, gypsum or microbial action
Impact Opportunity 4. Minimise the volume of residue to be stored
Bauxite Residue Reuse
The International Aluminium Institute (IAI) estimates that annual bauxite residue (BR) production will grow from 124 million tonnes (Mt) in 2019 to 178 Mt by 2040, and that the global inventory of bauxite residue can be expected to be 7 to 8 billion tonnes by 2040. The methods of safe disposal of BR have improved enormously in the last two decades but it is recognised that the BR has valuable properties and components that could be effectively used in the move towards a circular economy. Of the many and diverse uses that have been investigated, priority should be given to high volume applications.
Applicable SDGs: 9, 12, 15
Enablers:
Bauxite Residue as an additive to cement and concrete products
India: 100% red mud to cement
In 2020 Hindalco became the first company to achieve 100% red mud utilisation, by directing all of the bauxite residue from its 3 refineries to cement manufacture.
Europe: The ReActiv Project
The ReActiv Project aims to produce cements with a replacement of 30% of the clinker by modified bauxite residue as an enabler for the cement industry to consume the total production of the modified bauxite residue in Europe.
IAI: Global Initiatives
IAI has released the following key documents:
a. Portland Cement Clinker (PCC)
b. Supplementary Cementitious Materials (SCM)
d. Technology Roadmap: Maximising the Use of Bauxite Residue in Cement
Key points:
- Global cement production is sufficient to incorporate the total production of BR for the foreseeable future.
- BR addition contributes to the cement industry goal of lowering net CO2 emissions.
- BR addition to PCC and SCM reduces overall CO2 inventory.
- BR is already being used in PCC to improve energy efficiency and resource utilisation during clinker production at levels up to 5% BR : it is estimated that at least 3 Mtpa of BR is currently used in cement plants in Belarus, China Ukraine, India, Russia, Romania, Georgia, Moldova, Cyprus and Greece.
- Incorporation of up to 30% BR in SCM is possible.
- Feasibility depends on:
- cement manufacturer equipment
- raw materials
- BR composition
- proximity of BR to cement plant.
- Current challenges to widespread application:
- long-term durability and lack of standards for incorporating BR
- technical standards and regulatory frameworks are a critical area for progression, requiring investment, long-term durability testing, lobbying and cement industry support
- regulatory barriers including hazard classification of BR, chromium level, standards, transport and respirable titanium dioxide levels
- for PCC: sodium level and form, levels of impurities, moisture levels, Al/Fe ratio limitations, level of radioactivity, leaching behaviour and colour
- for SCM/blended cements: sodium level and form, additional processing, standards, moisture level, durability, level of radioactivity and colour
- plant-specific barriers: dust management, cement mix, alkalinity and BR composition.
- Actively pursuing areas of research/engagement with cement industry via IAI . Six key pathways have been established:
- overcome barriers and complete knowledge gaps
- establish joint research projects between alumina, cement and concrete producers to investigate use of BR in PCC and SCM/blended cements
- promote the use of BR in PCC and SCM/blended cements in sourcing and public procurement policies
- establish the level of interest and preparedness in incorporating BR in PCC and SCM/blended cements
- demonstrate benefits in CO2 emission reduction that can be achieved using BR in PCC and SCM/blended cements
- encourage use of BR in cement and concrete products to further the circular economy.
Bauxite residue in geopolymers/inorganic binders
- Geopolymers.
- BR as a filler in an inorganic binder.
- Other low-strength applications may still be an opportunity.
Bauxite residue in road construction
- Proven technology when using coarse material such as that found in Darling Range bauxite.
- Can be used as sub-grade or sub-base.
- Potential for use as a major component or binder for use in road construction.
- Potential mid- to high-volume usage.
Bauxite residue as a soil conditioner
- BR alkalinity can be used in the neutralisation of acid sulfate waters and soils and acid mine tailings
- BR can improve nutrient retention in agricultural applications .
Bauxite residue as a construction fill material
- Demonstrated using coarse residue material (>150 µm) – excellent compaction and drainage properties.
- Large volume reuse opportunity if aligned with large construction projects (up to 5 m of fill required for some projects in Western Australia; active research in Europe and elsewhere).
- Opportunity limited to producers that have a reasonable fraction of coarse material in their residue.
Extraction of metals from bauxite residue
- BR can be a source of its major components (Fe, Al, Si), and/or its minor components (Ti, Ga, Se, Rare Earth Elements (REEs)).
- Extraction of components will generally lead to the generation of other waste streams that will need to be managed/stored/valorized.
Other areas (low volume)
Other possible uses for lower volumes of BR include:
- Ceramics
- Pigments
- Catalysts
- Bricks.
Impact Opportunity 5. Ensure safety and sustainability of residue when stored
Applicable SDGs: 9, 12, 15
Significant global initiatives in place or in progress in 2020:
| Element | Initiative & status | |
| Regulatory |
Global Industry Standard on Tailings Management, August 2020 (GISTM), compiled by an independent expert panel convened by ICMM, UNEP and PRI. Mining Association of Canada Guide to the Management of Tailings Facilities. |
The GISTM is mandatory for all ICMM members. |
| Governance |
Reviewing and updating of internal standards and governance processes underway by most companies. Much greater transparency and more data now publicly available than ever before. |
Most company websites |
| Technical standards and guidelines | Revision and updates in progress. Several implementation guides in preparation. | e.g. MAC |
| Industry body initiatives |
ICMM driven improvement and aspirational goals
|
First stages of study due for completion by the end of 2020.
|
Questions to be discussed
Are there any technical uncertainties regarding the dewatering, compaction and storage of bauxite residue?
Given our process imperative of recovering liquor, are we in a generally better position than some other parts of the mining industry?
What could be done in the alumina technology space to improve tailings management?
Knowledge Gaps:
- Better understanding of the influence of bauxite residue properties on sedimentation and dewatering e.g. comprehensive review of the residue aspects of P266, PFPC (Boger/Scales etc).
- How could residue be further ‘coarsened’ to promote dewatering – more selective classification?
- Can centrifugation be a useful process in residue (or for other dewatering applications)?
Theme: Water
Applicable SDGs : 6, 12, 15, 17
The 2050 Water Goal for alumina production is:
- Zero net fresh water import
Impact Opportunity 6. Reduce fresh water consumption
Drawing on supplies of fresh/potable water for use in refineries will become increasingly difficult. It has become an accepted that fresh water is too a valuable resource for such an industrial application. Hence refineries will have to draw on alternative sources or change technology.
Enablers:
- collect and utilise rainwater
- treat lower grade sources via e.g., reverse osmosis
- collect and condense process steam from calcination and other unit operations.
Theme: Emissions
Applicable SDGs : 3, 12, 13, 17
The 2050 Emissions Goal for alumina production is:
- Meet or exceed all applicable environmental, health and safety standards in relation to emissions to soil, water and air, including zero net CO2e to air
Impact Opportunity 7. Eliminate emissions to soil, water and air
The emissions from a refinery can be broadly categorised as:
- Emissions to air: odour, caustic droplets, visible steam plumes, bauxite residue dust and other dust, including alumina dust in ship loading operations
- Carbon dioxide emissions, which are addressed in the Energy Theme
- Liquid Emissions to river, sea, groundwater and soil – process water discharges, leakage from residue liners and process pads
The following table provides context on aspects related to emissions
| Aspect | Contextual Summary |
| Regulatory |
In Australia there are State and National Environmental regulations. In Queensland there are no environmental restrictions on odour; however it is very important from the perspective of community concern. |
| Technical |
|
| Financial |
|
| Risk/Reward | The proximity of the refinery to the community may have a direct influence on how high the community expectation becomes for odour and visible steam plumes management. |
| Perception |
|
| Synergy with other Impact Opportunities |
|
| Liquid Emissions |
|
Enablers:
To be developed.
Theme Background Summaries
There is a Comments section for reader input at the end of each of these summary blogs.
Residue
The global inventory of bauxite residue was estimated to be approaching 3 billion tonnes (Bt) in 2010, and to reach 8 Bt by 2040.
Water
As global water demand continues to increase, shortages of natural supply will become increasingly common throughout the world. The SDG Goal to: ‘Substantially increase water-use efficiency and ensure sustainable withdrawals and supply of freshwater to address water scarcity and substantially reduce the number of people suffering from water scarcity’ addresses current and future water scarcity and provides general guidance to industry on a global basis. We aim to be zero consumers or positive contributors to fresh water supply in the regions in which we operate.
Energy
Aluminium is positioned to become the ‘green metal’ in the post-2050 decarbonized world, increasing its contribution to light-weighting transport and packaging while dramatically reducing its own carbon footprint and leveraging its iconic recyclability. A substantial increase in alumina output while transitioning to carbon neutral production will be required.
Emissions
Actual and potential emissions from alumina refineries include CO2, odour, VOCs, airborne toxics, caustic mists, visible steam and dusts to the air, and process liquors to water, ground and soil. The industry strives to maintain meet or exceed all applicable environmental, health and safety standards in relation to all emissions, including the commitment to zero CO2e to air by 2050, and to be in harmony with the communities in which it operates.
2 Comments
Submit a Comment
You must be logged in to post a comment.
Just four subjects of Energy, Residue, Water and Emissions are considered in the Themes. I think ‘Resource’ should be added here. As for energy renewable one exists, but resource bauxite is not renewable. Bauxite quality must be degrading year after year in spite of increased consumption. Then mining areas are expanding, consumption of energy and caustic soda must be increasing, amount of residues must be increasing with expanded BRDA. In order to meet such situation beneficiation leave degraded part in tail. That reduce the resource efficiency. Processing of lower grade bauxites and/or alternative process should be considered to increase the resource use efficiency (SDGs 9&12).
Improved Low Temperature Digestion Process: It must be a very useful process. I think that a better technical word for the process is ‘differential process’ by P. Smith (2009) rather than ILTD or Sumitomo process. There are some reasons. If comments are required, I will do it later.
Theme: Residue, Enablers…Neutralization by seawater… please add H2SO4 in the sentence.
IO4: Bauxite residue is a source of NaOH if it is recovered. The recovery does not reduce the amount though, it expands reuse of bauxite residue economically. Now, advanced membrane technology economically allows to recover NaOH after neutralization of bauxite residue by sulfuric acid (leachate Na2SO4).
IO5 Knowledge Gap: In order to consolidate the BRDA after lagoon process, Sumitomo used a paper drain method. It consolidated the area well to build chemical plants. The process may be useful to neutralize legacy BRDA.
IO4: Bauxite residue as a soil conditioner…alkalinity of bauxite residue is really useful source for acidic material, but when they reacted salt is generated. EC, for example, should be low enough for plants. The alkalinity comes from both accompanied soda in liquor and soda in solid residue, therefore, the soda content in it should be reduced before the treatment. Damage by the salt should be avoided.