Continuous improvements in technology have dramatically reduced or eliminated many of the environmental impacts traditionally associated with the use of coal. Some of the developments and measures being undertaken in the vital electricity generation and steelmaking industries are outlined below:
Electricity Generation
Reducing emissions of oxides of sulphur and nitrogen...
Modern power station technology is capable of reducing emissions of oxides of sulphur and nitrogen (SOx and NOx) and of particulates to meet stringent environmental requirements.
By treating flue gases, virtually all (99.5 per cent) of particulate matter can be removed. This is also the means by which a high proportion (over 90 per cent) of sulphur is prevented from reaching the atmosphere as sulphur dioxide.
Flue gas desulphurisation (FGD) is one means of meeting strict emission regulations when high sulphur coals are used. However, in many circumstances the most economical means of sulphur dioxide control is to use low sulphur coal. Australian export thermal coals are well suited in this regard.
Reducing Greenhouse Gas emissions...
Australia's electricity generators are keen to take on the world in achieving cleaner fossil fuel energy supply by agreeing to maximise their efficiency and aiming to achieve global best practice.
For information on the latest research and developments to reduce greenhouse gas emissions in the power sector visit the NewGenCoal website.
Iron and Steel Making
In blast furnace ironmaking, coke consumption has been reduced to a third of what it was 80 years ago, as have carbon dioxide emissions.
Research aimed at improving the chemical reactivity of coke is likely to allow the widespread use of new direct combustion technologies (the direct reduction of iron ore to iron in the one process and one chamber) in the near future.
The next generation of ironmaking furnaces is likely to be operated without coke, using 100 percent directly injected non-coking coals.
One such technology, the HIsmelt® process being tested in Kwinana, Western Australia, avoids the associated emissions from coke ovens and is significant for sustainable development because it accepts lower grades of iron ore than the blast furnace, does not require premium coals and has the potential to reduce the cost to end users.
HIsmelt® is a Direct Ironmaking process, in which iron ore fines and/or other iron containing materials and ordinary steaming coals are injected directly into a molten iron bath to produce a quality molten pig iron. It can be considered both as a potential replacement for the blast furnace and as a new source of low cost iron units for the Electric Arc Steelmaking industry.
There are substantial environmental benefits to the HIsmelt® technology when compared to the conventional coke oven/sinter plant/blast furnace ironmaking route. They include:-
- Use of lower grade and lower value iron ore fines, thereby minimising waste and contributing to the greater sustainability of iron ore mining;
- Elimination of environmentally unfriendly coke ovens, sinter plants and pellet plants; which are under increasing pressure from environmental regulatory agencies;
- High energy efficiency, due to minimal raw material preparation requirements, which leads to better greenhouse gas performance;
- No emissions of dioxins, furans or polycyclic-aromatic hydrocarbons (PAH's eg tars and phenols);
- Ability to utilise most steel plant wastes as a process input enabling iron and steel plants to move closer to the goal of Zero Waste;
For further details visit Rio Tinto's HIsmelt website at: http://www.hismelt.com.au
Other emerging coal based technologies which offer improvement in operating efficiency, economics, and in reducing environmental impacts - particularly in relation to emissions, include:
- ITmk3 - a variant of the current FASTMELT technology, where the coal-ore pellets are heated until partially melted. This allows hot screening to remove gangue from iron product.
- Tecnored - shaft furnace technology for producing BF type hot metal using coal-ore cold-bonded pellets.
Descriptions of these and similar technologies can be found at: