Located on the south-west coast near Stavanger, Tau is Norstone’s largest plant in Norway. Half the quarry’s production is shipped for export, while the rest is sold in Norway..
The primary gyratory crusher had seen its best days and was consuming excessive amounts of power. The quarry was looking to boost short-term production capacity, and the primary just couldn’t keep up.
A bigger expansion was on the horizon, including an investment in an in-pit primary crushing solution in five to seven years. So, how could the interim bottlenecks be solved?
Norstone called on Metso to assess the situation. The existing primary crusher had been commissioned in 1984. After careful evaluation, the decision was made to replace the spider, the top shell and the bottom shell.
Due to the project’s scope, Metso technicians frequented the site for countless hours of measuring, drawing and designing. It had to determine how to increase the crusher’s capacity while lowering the power draw. The final touch, wear part design, also played a key role in the project outcome.
Thanks to detailed planning and seamless co-operation between the two parties, the removal of old parts and installation and commissioning of new ones was completed in less than four weeks during a pre-planned shutdown in late 2014.
“We’ve always had a good relationship with Metso,” plant manager Marie Reumont said. “You can really see that the people visiting us are highly skilled, know what they are talking about, and offering us valuable advice.”
The results speak for themselves. The average power draw during operation dropped from 250kW to 170kW, while the average capacity increased from 900 to 1260 tonnes per hour at a 47 per cent load.
Reumont says the concave segments now last for about 2.4 million tonnes of work.
Metso was on site every three months to follow and monitor wear but the real work of optimising and finetuning is just beginning.
“I think there is always room for more improvement, however small, so we will keep monitoring this and working to maximise the optimisation,” Reumont said. “And because the results with Metso have been very good, we are looking into the possibility of further improvements on other machines.”
First up for optimisation is the secondary crusher. Because the cone produces a finer product, the goals for optimisation are different. Lifetime extension isn’t enough – the quality of the end product is crucial.
“We are pleased that Metso has understood our needs so we can work together in that direction,” Reumont said.