The Boliden smelter in Harjavalta, western Finland, is a traditional plant of handling copper and nickel concentrates and was, in fact, the location where the flash smelting method was developed in 1949. Today this method is used all over the world. The original copper smelter was established in eastern Finland in 1936 by Outokumpu Oy but the Second World War prompted its relocation in the western part of the country.
Since 2004 the Harjavalta smelter has been owned by Boliden, a major Swedish mining and metallurgical company. The smelter has two production lines, one for copper, and the other for nickel. The plant has the maximum capacity to handle 720,000 tonnes of copper concentrate and 250,000 tonnes of nickel concentrate.
The copper smelting line has four converters, of which the newest and biggest one was delivered by Kopar Oy in 2007. Here it is a question of a Peirce Smith Converter with an inside diameter of 3.9m and length of 10.3m, both figures indicated without brick lining.
“Our converters in the past made a bottleneck in the process, so we decided to acquire a new one that would replace the oldest and smallest converter. In the evaluation process for the new unit, there were several partners, both from inside Boliden and outside experts from Kopar,” explains Mr Vesa Helkala, project engineer.
Since Boliden has got another copper smelter, which is located in Skelleftehamn, Sweden the experts from the two smelter units analysed the overall situation and discussed intensively with Kopar experts prior to the purchasing decision. One particular aspect was to make sure that the new converter was to comply with environmental regulations.
“A smelter is not just another smelter that you can order from a manufacturers shelve but there is a lot of technical and process analyses involved before all parties know exactly what the project is all about. Fortunately we agreed upon a solution that has proved a very good one for us, “ Mr Helkala comments. In particular, he is satisfied with the speed of batches passing through the converter. “This was our bottleneck but is not any more.”
Along with the new converter the production of blister copper can be increased up to 14%. According to Mr Helkala, the smelting process has quite a few parameters that affect the process almost on a daily basis.
“We have four converters but most of the time only three are in use at a given time. We rotate the use of converters constantly,” he says.
The other three converters in the smelter are smaller and much older. “At some point we will renew some of them as well but there is no set timetable yet,” he concludes.
In addition to the PS converter, Kopar has delivered other products to the Harjavalta plant. Amongst them there are pneumatic feeding systems that are used to transfer copper concentrate to the smelter’s flash furnaces. The original Kopar delivery included two feeders but since the plant has got four feeders, the other two were later changed to comply with the Kopar specification.