Dampier Salt, Australia’s largest manufacturer and exporter of salt, recently completed a $3 million project to prevent corrosion for the next 25 years of a tunnel and conveyor system at Mistaken Island, near Dampier.
The company operates a salt field at Lake MacLeod and Dampier, in WA’s Pilbara region, from which it has shipped about 100 million tonnes of high quality salt since 1972.
Mistaken Island, located about two kilometres from the iron-ore shipping centre at Dampier, is used by the company to stockpile and ship out the dry salt trucked in from the mainland via a causeway.
Perth-based consulting engineers, Gutteridge Haskins & Davey Pty Ltd (GHD), was engaged by the Rio Tinto subsidiary to investigate and design facility upgrades in two areas of the existing plant.
The Dampier operation involves harvesting and washing salt, wet and dry stockpiling and transfer to ships.
The dry salt stockpile is assembled on Mistaken Island and the original reclaim tunnel and conveyor were in a poor state due to years of corrosion.
Likewise, the wet salt reclaim conveyor in the washing plant was experiencing significant spillage problems and required extending.
In both instances it was critical that implementing the construction works to construct a new reclaim system and improved wet salt reclaim conveyor have minimal effect on production.
GHD designed a new tunnel and conveyor hung from the roof of the tunnel to keep steelwork away from the highly saline water zone at the floor.
GHD structural engineering manager Pim Birss said a special concrete mix was developed to protect against the saline environment and salt spills.
“The design and construction process had to ensure that the stockpile remained live at all times, and that no interruption was made to the outloading of ships using the original tunnel.”
Construction was completed on time and within budget.
