Can high purity alumina
be sustainably produced?
Advanced Energy Minerals details how its unique chlorine leach–
crystalline purification process can reduce the carbon footprint
of high purity alumina production
HOW can high purity alumina be produced
sustainably? Advanced Energy Minerals (AEM)
considers sustainable production to be of the utmost
importance.
The company manufactures ultra-high purity alumina
(HPA) at its production plant in Cap-Chat, Quebec,
Canada, that delivers under the SupALOX™ brand.
How HPA production increases carbon emissions
It is well known that the conventional alkaloid
process for manufacturing HPA is a notorious
‘energy hog’, yielding a typical carbon footprint of
12.3 tonnes of CO2 emitted per tonne of high purity alumina. This is an incredibly high ratio compared
even to the energy consumption within the cement
and steel industries with their ratios of only 0.6 and
1.85 tonnes of CO2 emitted per tonne of cement (2,3)
and steel (4,5,6), respectively.
The alkaloid process for high purity alumina also
relies on expensive, carbon-intensive aluminium
metal as its feedstock, which clearly will not be
acceptable in the future.
Shocked by numbers like these, consumers
and investors are making decisions based on
sustainability. For example, the Norwegian sovereign fund – one of the largest sustainability projects with
more than €1.1tr invested7
– now requires each of
the 9,000+ companies it invests in to show plans
to reach net zero by 20508
. Therefore, it is clear
that the alumina industry needs an alternative
to manufacture 99.999%-pure 5N HPA at a
competitive price.
The market has a strong demand for HPA that will
increase rapidly in years to come. This is because
HPA has excellent properties in terms of chemical
stability, its high melting point, and high mechanical
strength and hardness. It has good thermal
conductivity but high electrical insulation.
High purity alumina takes on different crystalline
structures known as alpha (α), beta (β), and gamma
(γ), with each possessing different properties. α-HPA
has a low specific surface area and is very resistant
to high temperatures. Because it is inert, it has
almost no catalytic activity. γ-alumina has excellent
dispersion and a higher specific surface area, but it is
inert and provides high activity (9)
.
Emissions Scopes according to the Greenhouse Gas Protocol (10,11)
Scope 1 Emissions from sources that a
company owns or controls directly.
Scope 2 Emissions that a company
causes indirectly when the energy it
purchases and uses is produced.
Scope 3 Emissions not produced by
the company itself, and not the result
of activities from assets owned or
controlled by them, but by those that
it is indirectly responsible for, up and
down its value chain. Scope 3 emissions
include all sources not within the
boundaries of Scopes 1 and 2.
Reducing the industry’s carbon footprint
The first step in reducing the carbon footprint and
environmental effects of the HPA industry is to
reduce the power requirement for manufacturing
processes. This starts with the design of the
processes and the manufacturing plant to implement
them. As a basis to reduce power consumption,
hydro metallurgy processes use much less power
than thermal process steps.
AEM’s proven chlorine leach–crystalline purification
(CLCP) process currently emits 12% fewer carbon
emissions than the alkaloid process and is expected
to reduce to zero in Q3 of 2023. Close co-operation
with the laboratory is the basis for continuous
improvement in the plant. This provides the plan for
eliminating the Scope 1 category of emissions.
The CLCP process produces almost zero waste.
Hydrochloric acid, an important input chemical, is
recycled many times within the process before being discharged. As a by-product, it predominantly takes
the form of aluminium chloride, which is sold for use
in water treatment. The water from our processes
that we do not recycle is treated and released under
strict guidelines.
The next step is to source the required power from
green sources. A location rich in hydropower and
wind farms is of the essence. This leads to both
predictable pricing and fulfilment of environmental
criteria. By-products are produced with
hydropower and, as a result, there are no Scope 2
emissions.
Manufacturing high purity alumina does not occur
in a vacuum. This means that reducing Scope 3
emissions requires paying attention to the inputs and
outputs of production. The feedstock must arrive and
bring with it a carbon footprint of zero. This can be
achieved if the supplier uses hydro or wind power
exclusively, ideally within the company from its
dams or wind installations. It is, of course, simplest
if the supply is from a secured source located
nearby. An alternative feedstock is aluminium from
decommissioned factories.
The product going out must match the customers’
requirements exactly so that they can minimise their
process steps and maximise their productivity. This
means that high purity alumina cannot be seen as
a commodity product where the customisation is
left to the customer, a wide and versatile product
portfolio is needed. Powder particle size can be
controlled both at the crystal-growing stage and
via subsequent milling – although the latter requires
careful control to avoid contamination by the grinding
media. Powder must be tailored to a customer’s
specific requirements for particle size, densification,
and doping. Pellets (compacted powder in a ‘puck’
shape) must also meet exacting specifications to
fulfil their applications.
Looking ahead
Customisation to meet special requirements
involves simulation, development in the laboratory,
and transfer to production. Quality controls after
manufacturing complete the technical involvement
to the benefit of the customer, with a location
convenient to North American and European markets
that simplifies shipping.
Even if the site is not in a location where every turn of a spade is audited and certified, transparency must be maintained for internal and external purposes. All systems are running to identify where things come from and where they are going and logging of operations is ongoing in preparation for internal and external audits. As we have seen, sustainability depends on many factors. Process design, the reduction of power requirements, an advantageous site, green energy sources, clean feedstocks, and customised products are all important to sustainably produce and deliver ultra-high purity alumina.
Even if the site is not in a location where every turn of a spade is audited and certified, transparency must be maintained for internal and external purposes. All systems are running to identify where things come from and where they are going and logging of operations is ongoing in preparation for internal and external audits. As we have seen, sustainability depends on many factors. Process design, the reduction of power requirements, an advantageous site, green energy sources, clean feedstocks, and customised products are all important to sustainably produce and deliver ultra-high purity alumina.
Customisation to meet
special requirements
involves simulation,
development in the
laboratory, and transfer
to production
References
1. AEM Internal data
2. https://news.wttw.com/2022/06/22/cement-carbon-dioxide-emissions-quietly-double-20-years
3. https://essd.copernicus.org/articles/13/1667/2021/ “CDIAC-FF:
global and national CO2 emissions from fossil fuel combustion and
cement manufacture: 1751–2017”
4. https://www.recyclingtoday.com/news/worldsteel-co2-report/
5. https://www.iea.org/reports/iron-and-steel
6. https://www.mckinsey.com/industries/metals-and-mining/our-insights/decarbonization-challenge-for-steel
7. https://www.reuters.com/business/sustainable-business/norways-sovereign-wealth-fund-tells-companies-set-zero-emission-goals-2022-09-20/
8. https://www.weforum.org/agenda/2022/09/norways-massive-sovereign-wealth-fund-sets-net-zero-goal/
9. https://www.innovationnewsnetwork.com/ultra-high-purity-alumina-sustainably-manufactured-canada/20960/
10. https://www.nationalgrid.com/stories/energy-explained/what-are-scope-1-2-3-carbon-emissions
11. https://ghgprotocol.org
Daniele Fregonese
SVP for Sales & Marketing
Advanced Energy Minerals Limited
+1 418 786 5492
dfregonese@aem-international.com
www.supalox.com
