Our smelting plant is located in Larymna, about 130 km N/NE of Athens. The plant processes the nickelferrous ores (laterites) we mine to produce ferronickel with an 18%-24% nickel content.
This is the raw material for the industrial production of stainless steel in Europe. The total quantity of ore processed per year is 2,500,000 tonnes, equating to an annual ferronickel production of around 18,000-20,000 tonnes.
The processing of the ore at Larymna takes place in 4 phases:
Phase 1: Handling of raw materials and preparation of the metallurgical mixture.
Ore is received from our mines at Kastoria, Agios Ioannis
Each ore has different characteristics:
- Euboea ore is high in iron and silica
- Agios Ioannis ore is high in iron but lower in silica
- Agios Ioannis and Euboea contain around 1% nickel on a dry basis (db) and around 6% moisture.
- Kastoria ore contains significant magnesium, is relatively low in iron, has high silica, contains around1.3% nickel db, but is also wetter, with around 11% moisture
- Turkish ore has a similar magnesium content to Kastoria ore. The nickel content is expected to be around 1.4% while the moisture is around16%
A typical analysis of the metallurgical mixture is: Kastoria Ore 15%, Agios Ioannis Ore 30%, Euboea Ore 55%, Solid Fuels (coal and lignite) approximately 200-250 kg/tonne of raw ore.
The ore, already crushed to -15 mm, the lignite and the coal reach the plant by road or sea and are stored at the raw material yards, where they are distributed with weighing cranes, so that the desirable ratio is ensured before moving via conveyor belts to the second phase of processing.
Phase 2: Pre-heating and pre-reduction in the Rotary Kilns
We operate four rotary kilns. Two are 90 m long and 4.2 m diameter, one 90m long and 5.2 m diameter, while the fourth is 126 m long and 6.1 m diameter, one of the largest in Europe.
The rotary kilns can process material at 485tph which is equivalent to 3.8Mtpa. Temperatures are 400°C at the entrance and 850°C at the exit. As the crushed ore passes through them, the nickel and iron oxides are dried and pre-reduced.
Phase 3: Electric Furnace reductive smelting
The product of the Rotary Kilns is fed into five Submerged Arc Electric Furnaces. Each of the furnaces is 6m high; four being 13m in diameter, while the fifth has an 18m diameter. The temperature developed with the aid of the electric power is 1600o C and allows the reductive smelting of the fed material and the formation of two separate phases. One metallic containing all of the nickel and part of the iron and one slag phase containing oxides of the gang material of the calcine, that is the remaining part of iron silica, calcium, alumina and magnesium mainly .
The metallic and slag phases are removed systematically from the furnace. The metallic phase for further treatment, nickel enrichment and refinining and the slag for side exploitation and dumping. The electric furnace slag produced comprising about 85% of the feed is granulated with a strong stream of seawater.
Phase 4: Enrichment - Refining in OBM type Converters
The Electric Furnace product with suitable vessels of 50 tons capacity and derrick of capacity of 100 tons is fed to OBM type Converters. With oxygen and propane blowing through the bottom, a quantity of iron is oxidized resulting to the enrichment
of the ferronickel to the final desirable Nickel concentration, which is typically 20%.
There are two Converters of capacity 50 tons each. At the same time the product is refined, with the addition of proper fluxes. In this way sulphur and phosphor concentrations are limited to the marketable values. During the process the temperatures are 1600-1700° C.
When completed, the final smelted product is granulated. The size of the granules varies between +3 -40 mm and is the final product, which is pilled in reference with its Nickel concentration and is loaded from Larymna’s port to the market.
The slag produced during the refining is a by-product, which after milling to a size of -5 mm, is sold as heavy inert material for the production of special type of concrete and for covering of oil tubes or other similar works, in Europe, North Africa and Middle East.