The smelter wants to restart its mothballed sinter plant after problems with the new multi-million-dollar TSL furnace.
It is seeking permission to do so from the Environment Protection Authority, but there are fears lead-dust emissions will increase as a result.
Nyrstar closed the sinter plant - which fed the blast furnace - earlier this year.
Its workers were dispersed to other areas, but will need to be recalled if the sinter plant begins operating again.
Meanwhile, the company said an incident had taken place with the hearth of the primary smelter and led to a shutdown.
Repairs will result in the TSL furnace being down for a number of weeks and options are being considered including restarting the sinter plant to maintain production.
The cause of the failure is being investigated.
The cost of repairs to the furnace and of the restarting of the sinter plant are estimated in the tens of millions of dollars.
The sinter plant is needed again to provide supply to the blast furnace so that production can be continued including that of gold and silver which is forward-sold.
New owner Trafigura is better placed to cope with the financial demands than the previous ownership of Nyrstar.
The problems with the TSL furnace happened only a short time after Trafigura took over.
Some observers speculated that Nyrstar could have been forced to close if the debt burden had happened before it could assume new ownership.
It could also have resulted in millions of dollars being wiped off the buying price by Trafigura.
The company hosted a farewell dinner for the sinter plant staff at the Function Centre at Memorial Oval earlier this year. A commemorative booklet was produced.
The latest development is seen as a strategic response to troubles in production.
Keith Baldry, science and information director of the EPA, told ABC radio on Monday that it was unfortunate that the sinter plant may resume operations, but the agency expected the company to do "everything reasonably possible" to minimise emissions.
He said emissions levels were now well below limits.
It was a "complicated process" to reactivate "an old piece of plant," he said.
He said the company had approached the authority about the potential restart, but had yet to formally make a request for the works.
Asked whether lead emissions would rise after a restart, he said more information would need to be provided to the authority and assessed before any potential impacts were known.
Lead-in-air emissions are now "compliant".
Asked whether the authority was likely to approve the request, he said it would depend on the information that formed part of the company's formal request.
The sinter plant is thought to be about 80 years old.
If reactivated, the plant is believed likely to be used for only a limited time or until the TSL furnace is repaired and operational.