CORPORATE TRENDS — Expanding, modifying Harjavalta

The 50-year-old Harjavalta copper and nickel works in eastern Finland are being expanded and modified. The owner, Outokumpu, plans to increase the copper smelting and electrolytic refining capacity by more than 60% and raise the nickel production by 75% over the 1993-96 output.

The Outokumpu copper orebody, one of the richest reserves in western Europe, was identified in 1910. A copper smelter went into service at Imatra on the Finnish-Soviet border in 1936, while plans were being drawn up for a copper refinery in the area. Because of war between Finland and the old Soviet Union in 1939-40, Outokumpu moved its copper production to western Finland; a copper semis plant was built at Pori on the west coast in 1940, followed by an electrolytic refinery a year later.

In 1944, with Soviet troops closing on Imatra, Finland’s military leaders ordered that the copper smelter be moved and Harjavalta, 30 km from Pori, was chosen as the new site because of its proximity to the electrolysis plant and hydroelectric power. On Christmas Eve of that year, power was connected to the Harjavalta furnace, and the first batch of copper matte was drawn two weeks later.

In post-Second World War Finland, electricity was in short supply and the price for the commodity soared. Outokumpu resorted to an old idea of autogenous smelting to design a new type of smelter which would require hardly any external energy. The new technology was flash smelting, a pyrometallurgical process for smelting of copper sulphide concentrate involving the blowing of copper concentrate and air into a furnace, whereby the oxygen ignites and the resulting exothermic reaction smelts the charge. Construction of the new smelter started at Harjavalta in 1947, and two years later the plant was in industrial-scale production.

Other metals started to claim greater importance for the company in the 1950s. An example is the discovery of the Kotalahti nickel deposit in 1954. Flash smelting could be as easily applied to nickel as to copper concentrate. But the extraction of nickel from matte posed a new metallurgical problem. An in-house hydrometallurgical process was developed — nickel electrowinning with insoluble anodes was designed for matter with a high copper content, as in the case with the concentrate from Kotalahti. The first cathode nickel came off the line at Harjavalta in 1960.

Until the 1970s, Harjavalta’s copper and nickel production relied on domestic raw material sources. By the turn of the 1990s, three-fourths of Harjavalta’s copper concentrate, and more than half of the nickel concentrate, came from abroad. Last year, with the closure of the Enonkoski and Vammala nickel mines, the nickel smelter lost its last source of domestic raw materials from Outokumpu mines.

Nickel smelting capacity will nearly double to 32,000 tonnes per year (tpy). The entire new capacity will be in the form of briquettes, while cathode nickel production will remain at the current capacity of 18,000 tpy. Copper-smelting capacity will increase to 160,000 from 100,000 tpy. The copper refinery at Pori will also be expanded in connection with the Harjavalta project, with capacity increasing to 125,000 from 75,000 tpy. Byproduct recovery, for example, of cobalt and precious metals will increase. The acid plant will be expanded to 560,000 tpy of sulphuric acid and 45,000 tpy of liquid sulphur dioxide. The liquid oxygen plant will be expanded and a hydrogen plant will be built to satisfy the hydrogen need of the new nickel reduction process.

On the environmental side, the modification plan will reduce the total sulphur dioxide emission to about 25 kg for each tonne of metal produced (worse polluting nickel smelters elsewhere may reach levels of up to 10,000 kg per tonne). By 1995, dust emissions are expected to be less than 50 tpy, which represents a 95% reduction from 1990.

— From a recent issue of “Outokumpu News.”