Well, basically it is a measure of all greenhouse gases a specified entity (eg an individual, a factory, a country) produces in a specified amount of time (a day, a year, a lifetime etc), and has units of tonnes (or kg) of carbon dioxide equivalent.Thus, the carbon footprint is a measure of how much we affect the environment.
Despite world attention, humans emit more greenhouse gases every year than they did the year before.
The mineral processing and metal production sector is endeavouring to identify opportunities to improve the sustainability of its operations and reduce its greenhouse gas footprint, with improved energy efficiency receiving increased attention. However, if truly sustainable outcomes are to be obtained it is essential that a life cycle approach be adopted in evaluating these opportunities.
Low carbon footprint metal extraction
Low Carbon Footprint
• Sricharan Sunder (09MT3008)
• Piyush Verma (09MT3018)
• Kislaya Dubey (09MT1006)
Department of Metallurgical and Materials Engineering
Indian Institute ofTechnology, Kharagpur
A measure of the total amount of carbon
dioxide (CO2) and methane (CH4) emissions of a
defined population, system or activity, considering
all relevant sources, sinks and storage within the
spatial and temporal boundary of the
population, system or activity of interest. Calculated
as carbon dioxide equivalent (CO2e) using the
relevant 100-year global warming
What is Carbon Footprint
Why we need to reduce ?
• The accumulation of carbon dioxide in the environment
is recognized as a major contributor to the Global
Warming Problem caused by this Green House Gas.
• The main influences on carbon footprints include
population, economic output, and energy and carbon
intensity of the economy.
Where should the focus be?
•By adopting techniques that use non carbon
containing fuels such that carbon dioxide is not
formed anywhere in between its production .
•Minimizing the number of steps in a Metal
production such that fuel consumption is reduced
if we have to use a Carbon-Fuel.
• Increasing demand for metals, declining ore grades
and complex new deposits are all contributing to an
increase in greenhouse emissions from primary metal
• As a result, the mineral processing and metal
production sector is coming under increasing pressure
to reduce its energy consumption and GHG emissions
and improve the overall sustainability of its
World metal production and ore processing rates
Copper Nickel Lead Zinc Iron/steel Aluminium
Current Metal 15.5 1.4 8.7 11.7 1327 36.3
Ore 1914 111 193 260 2633 202
2030 Metal 31.4 2.7 14.8 19.2 2540 78.0
Ore 4984 273 411 533 5040 434
Global Energy Consumption and Associated Carbon
• Number of technologies under development in the
metal extraction stage of Iron/Steel and
Aluminium which may realize some of the
opportunities for reducing the energy and
greenhouse footprints of primary metal production.
• Mineral processing offers less opportunities for
reducing energy consumption and greenhouse gas
emissions compared to metal extraction.
• New technologies producing energy savings if
incorporated optimally into comminution circuits
High pressure grinding rolls.
• These technologies in combination with others (e.g.
improved circuit design), may possibly achieve the
50% improvement in energy efficiency for
Charcoal from biomass
1. Woodchar or biomass char is considered renewable
because the carbon cycle via wood ( biomass)is
very short (5–10 years) compared to fossil coal
(approximately 100 million years).
2. Coke contributes 75% to the GHG emissions from
steel production . Replacement of coke with charcoal
derived from biomass would reduce GHG, as the
biomass comes with a greenhouse gas credit due to
the carbon dioxide sequestered during its formation.
• Impossible to operate large blast furnaces with 100%
substitution of charcoal-lower crushing strength,(20%
being considered practical.)
• Other Methods to Reduce Carbon footprint in Steel
• Dry granulation of slag
• Bath smelting – HIsmelt
• Using Drained cathodes
• The use of aluminium-wetted and drained
cathodes will enable a reduction in the thickness
of the metal pad, which will allow ultimate
stability of this interface to be achieved. anode-
to-cathode distance (ACD) is also
reduced, thereby producing a lower cell voltage.
The lower cell voltage and higher current
efficiency will reduce the power consumption of
High pressure grinding rolls
• Since its first commercial application in 1985, high pressure
grinding rolls have become a near standard unit operation for
pre-grinding cement clinker, and grinding of raw materials
such as slag, coal and lime in the cement industry. It has
subsequently been utilised in the diamond industry for
selective liberation.The broader use of high pressure
grinding rolls for metalliferous minerals has only been
considered more recently. Initial concerns over wear rate of
the rolls have been addressed, and as a result there are
strong signs of increasing interest, particularly in the
processing of gold, copper and iron ores.While energy
reductions in the order of 30–50% have been suggested for
the high pressure grinding rolls based on cement industry
experience, reductions in the order of 20% are more likely for
• Three stirred mill types have gained industry acceptance
for fine and ultra-fine grinding duties, ie., the tower mill,
the detritor mill and the IsaMill.The first two mills are
vertical stirred mills with steel spirals and long pins
respectively to agitate the mill charge, while the latter
mill is a large horizontal stirred mill with discs as stirrers.
The major advantage of stirred mills over traditional ball
mills are their ability to effectively use smaller grinding
media for fine and ultra-fine grinding to achieve high
energy efficiency at high mill throughput . It has been
reported that stirred mills are up to 50% more energy-
efficient than conventional ball mills for products finer
than 100 μm
• The results from a number of life cycle assessments of
primary metal production processes, together with predicted
future ore grades, metal production rates and liberation
size, have been used to show that endeavours to reduce the
energy consumption and associated GHG emissions from
primary metal production should mainly focus on the metal
extraction stage of the metal life cycle, and that there is
considerable scope to make significant reductions
here, particularly for steel and aluminium.While the
contribution of the mining and mineral processing stage to
energy consumption and GHG emissions can be expected to
increase in the future as a result of a deterioration in the
quality of ores, and will present opportunities for reducing
these impacts by improving the energy efficiency of
comminution, these opportunities will still be appreciably
less than those from the metal extraction and refining stage
• Images taken from Google Images and