Two types of nickel ore are extracted for use globally: nickel sulphide and nickel laterite. Nickel sulphide ores are generally derived from volcanic or hydrothermal processes in sub-tropical regions. In contrast, nickel laterite forms during the weathering of parent or source rock from the ultramafic group with less than 45% silica in tropical or equatorial areas. Prof. Dr. Andika Pramono, Senior Researcher at the Research Center for Metallurgy and Materials, National Research and Innovation Agency in Indonesia, kindly shared his expertise on the subject.
By Joanne McIntyre, Stainless Steel World
Nickel laterite ore
Nickel lateritic ore is a metallic mineral resulting from the weathering process and mineral enrichment in ultramafic rocks, which are peridotites containing less than 45% silica. The ultramafic process yields different characters and profiles of nickel laterites. Factors affecting the formation of nickel lateritic ores include the source rocks, climate, chemical reagents, vegetation, geological structure, topography, and time.
Indonesia has one of the largest nickel reserves in the world. In 2013, Indonesia became the leading nickel ore exporter with an export capacity of about 43% of the global total, followed by the Philippines. In 2016 Indonesia’s nickel reserves from laterite and sulphide soils were estimated at 221 million tons. Nickel lateritic ores in Indonesia are located mostly in the eastern regions, such as Southeast Sulawesi, Halmahera, North Moluccas, and Waigeo Islands – Papua.
One type of nickel lateritic ore, known as saprolite and with a nickel content of over 1.8%, has been processed into ferronickel (FeNi) as the raw material for manufacturing stainless steel. In Indonesia, ferronickel production is carried out by state-owned company PT ANTAM in Pomalaa, whereas foreign investments held by PT Vale Indonesia in Sorowako produce nickel matte. Sumitomo Metal Mining (SMM) uses nickel laterites from Indonesia and New Caledonia to manufacture its ferronickel stainless steel.
The types of stainless steel produced from ferronickel are austenitic series 200 – 300. These grades are non-magnetic and have a nickel range of 8.5% – 25% for improved corrosion resistance. Non-ferronickel steel is called ferritic stainless steel. The world’s ferronickel stainless-steel use comprises of about 66% of the total.
Refining from laterite ore
In refining nickel from nickel sulphide, open cut or underground mining is followed by flotation and smelting of the concentration to produce nickel matte. The matte is refined further to produce nickel metal.
Refining nickel laterite is a very different process and is dependent on whether the ore is a limonite mineral with a nickel content of less than 1.5%, or saprolite with over 1.8%. Limonite requires various subsequent processes after mining, such as the nickel pig iron route covering drying – sintering – blast furnace smelting with the end result of nickel pig iron (NPI). NPI is the raw material for lateritic steel. Another process is high-pressure acid leaching (HPAL) with the end results of sulphides or hydroxides; and the Caron process with the end result of carbonates.
With saprolite, refinement can be carried out using the rotary kiln electric furnace method to produce ferronickel or nickel matte.
Competitive advantage?
Whether or not nickel laterite ore is advantageous depends on a country’s resources. For example, Indonesia high-grade iron ores reserves are only about 100 million tons, which is not economical to exploit, but it has abundant nickel lateritic ores. These are processed into semi-finished or finished commodities and exported, increasing national industrial competitiveness and adding to Indonesia’s lateritic mineral. China has invested a great deal in Morowali, Indonesia, to exploit nickel laterite minerals. They focus on the capacity of limonitic minerals to produce high-strength steel in a strategic collaboration at Indonesia Morowali Industrial Park (IMIP). This industrial park focuses on developing nickel lateritic ores for stainless steel production.
The natural content of nickel in nickel pig iron determines the superior properties of nickel lateritic steel, which are high strength, good corrosion resistance, and good weldability.
Proportion of nickel
Data from the US Geological Survey mentions that nickel lateritic ores comprise about 60% of nickel resources and nickel sulphide 40%. Global nickel consumption is dominated by stainless steel (approximately 66% to 73%), followed by alloys, special steels, electroplating, batteries, and other uses. Up to 2016, the production of stainless steel smelting reached about 44 million tons, with 1.4 million tons of primary nickel used in its production. Over 75% of stainless steel is austenitic 300 series with 8-20% Ni, and the 200 series with a lower nickel content. As mentioned previously, austenitic stainless steel is made using ferronickel, instead of nickel sulphide, as raw a material. The production of rough ferronickel or nickel pig iron is concentrated in China and Indonesia. The data shows an increase in production tonnage in both countries since 2013.
In conclusion
High strength lateritic steel based on nickel pig iron is an emerging commodity competing with conventional steel based on iron ores. The world should focus on this type of structural steel with high strength, good corrosion resistance, and good weldability.
Potential applications include railways, mechanical fasteners, on-shore infrastructures, and heavy machinery. The investment strategy should consider countries with abundant nickel lateritic ores reserves, such as Indonesia, the Philippines, and New Caledonia.
About Dr. Pramono
From 2006 – 2008 Dr. Pramono was division head of physical metallurgy and metallurgy manufacture of Research Center for Metallurgy and Materials (RCMM LIPI). From 2008 – 2010 he was the division head of materials conservation. From 2010 – 2019 he held the position of Director, and during this period nickel lateritic steel was brought to national attention by RCMM LIPI through R&D teams, scientific activities, and track records. In 2018 RCMM LIPI was appointed by the Ministry of Research and Technology of Indonesia as the national centre of excellence for lateritic steels. In 2021 LIPI – the Indonesian Institute of Sciences – merged into the National Research and Innovation Agency (Badan Riset dan Inovasi Nasional, or BRIN). Dr. Pramono is currently doing R&D in superconducting materials and biocompatible materials for implants. For information visit www.brin.go.id.
