DOING SOME DIGGING – Major stride to reduce Sudbury’s SO2 emissions

SUDBURY, ONTARIO - We are pleased to note that the world's second largest nickel miner, INCO LIMITED, is making new...
SUDBURY, ONTARIO - We are pleased to note that the world's second largest nickel miner, INCO LIMITED, is making news on the technology front these days, despite the takeover battles that surround it.

Last week Inco announced the commissioning of a new, state-of-the-art $115-million facility to reduce sulphur dioxide emissions from its Sudbury operations by 34%. Using unique fluid bed roaster (FBR) off-gas scrubbing technology, the FBR SO2 Abatement Project will lower allowable emissions from the current regulatory limit of 265 kilotonnes to 175 kilotonnes annually. The project is scheduled for completion by the end of December 2006, but could possibly be fully operational by early fall.

Since the Ontario government introduced the Countdown Acid Rain Program in 1986, Inco has spent close to $1 billion to reduce SO2 emissions at its Sudbury operations. The FBR project has the added benefit of decreasing total metal emissions of nickel, copper, arsenic and lead by 80 to 100 tonnes/year. With this latest improvement, Inco will have cut total metal emissions at its Copper Cliff smelter by 80% over 1988 levels, and reduced overall SO2 emissions by 90% since 1970. Inco's goal is to lower the SO2 emissions to 66 kilotonnes by 2015. (Note that these levels pertain only to Inco's Copper Cliff smelter, and do not apply to Falconbridge's smelter in the vicinity of Sudbury.)

Fluid bed roasting is part of the smelting process in which nickel sulphide is roasted to make nickel oxide feed for carbonyl refining. The FBR SO2 Abatement Project involves three main components:
- construction of a gas-cleaning facility adjacent to the existing FBR plant at the smelter;
- expansion of the existing acid plant to handle clean SO2 from the new gas-scrubbing facility; and
- construction of a weak acid treatment plant at the Copper Cliff mill filter plant to replace the current flash furnace slime system and allow for treatment of metals scrubbed by the gas-cleaning facility.

From Inco's June 23 news release, its 2003 Environmental, Health & Safety Report, information from Brooke Yeates of Inco Sudbury and my own calculations, I have put together a table of allowable SO2 emissions and actual SO2 emissions (in kilotonnes) from Inco's Sudbury operations:

YearAllowable Actual

19701,750 kt
1988875 kt>700 kt
1992416 kt
1997265 kt200 kt
1998265 kt235 kt
1999265 kt221 kt
2000265 kt223 kt
2001265 kt232 kt
2002265 kt243 kt
2003265 kt169 kt
2004265 kt
2005265 kt
Dec'06175 kt
2015 66 kt

As well, I have the figures for Inco Sudbury's nickel production for 1970 (398 million lb), 1988 (393.8 million lb), 2005 (216.0 million lb) and 2006 estimate (258 million lb).

"Allowable emissions" means the amount that regulators will allow within one year, without fining the company, whereas actual emissions are the total SO2 released in a year.

There are so many gaps in my data that analysis is difficult. To make a fair comparison, it would be necessary to complete the table with actual emissions and the amounts of metals production in those years. However, if the actual emissions are close to the allowable limits, then this will be a remarkable improvement over 45 years.

However, I can't help thinking about the hydrometallurgical option for metal recovery staring Inco in the face, with its promise of no airborne emissions of either SO2 or metals. Shouldn't that really be the next step? Inco has invested heavily in the research and development of a hydromet process for recovering nickel, copper and cobalt from the Voisey's Bay sulphide ore, currently being tested at its Argentia, Nfld., demonstration plant.

A fly in the ointment is that the Argentia method is not amenable to recovering the PGMs that are fortuitously absent from Voisey's Bay ore, but abundant in some of Inco's Sudbury Basin ore. Couldn't additional research look for a solution to this shortcoming?

Of course Inco has a lot invested in smelter technology in Sudbury, but the operations have a long, long life ahead of them. Planning to gradually convert the smelter-based facilities to hydromet would make a lot of sense. It would allow for major environmental improvements and possibly reduce operating expenses down the road, by being able to bypass the current acid production facilities. Starting such a conversion now would make really good use of the unprecedented profits that are currently coming Inco's way.


Your email address will not be published. Required fields are marked *