Rebuild results in a 30% drop in primary crusher power draw at Norstone Tau.

When an investment in brand new equipment is not feasible, a rebuild is an option that can also result in significant improvements. 

This was the case at Norstone Tau in 2012. Located on the southwest coast near Stavanger, Norway, Tau is Norstone’s largest plant in the country. Half of the quarry’s production is shipped for export, while the rest is sold in Norway, with biggest customers being asphalt producers.
The primary gyratory crusher had seen its best days and was consuming excessive amounts of power. The quarry was looking for ways to boost short-term production capacity, and the primary just couldn’t keep up. But a bigger expansion was also on the horizon, and likely including an investment in an in-pit primary crushing solution in 5 to 7 years. So, how to solve the interim bottlenecks?

Seamless collaboration helped meet deadlines
Norstone decided to call on Metso’s knowledge to assess the situation. The existing primary crusher, a Svedala Superior 54-74, 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 nature and scope of the project, Metso experts frequented the site to share experiences and requirements with Norstone. Countless hours of measuring, drawing and designing ensued. Metso had to figure out 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 outcome of the project.

Thanks to detailed planning and seamless cooperation between the two parties, the removal of the old parts and the installation and commissioning of the new ones was completed in less than 4 weeks during a pre-planned shutdown in late 2014.

“We have always had good collaboration with Metso. You can really see that the people visiting us are highly skilled, they know what they are talking about, and they’re actually offering us valuable advice,” says Plant Manager Marie Reumont.

The results speak for themselves. The average power draw during operation has dropped from 250 kW to 170 kW, while the average capacity has gone from 900 tons per hour to 1260 tons per hour at a 47% load.

Wear parts can be bought anywhere, expertise cannot
According to Marie Reumont, the concave segments now last for about 2.4 million tons, which was also the goal. At first, Metso was on site every 3 months to help follow and monitor wear and to establish a routine.

But the real work of optimizing and fine tuning is only starting. “I think that there is always room for more improvement, however small, so we will keep monitoring this and working to maximize the optimization,” Reumont says.

“And because the results with Metso have been very good, we are considering the possibility of further improvements on other machines,” she continues.

First up for optimization is the secondary crusher. Because the cone produces a finer product, the goals for optimization are somewhat different. Lifetime extension is not enough; the quality of the end product is another crucial parameter. “We are pleased that Metso has understood our needs so that we can work together in that direction,” the plant manager concludes.