Nickel is a ferromagnetic element, ranking as the fifth most abundant element on Earth after silicon, oxygen, iron, and magnesium. It has the highest concentration in the Earth’s core, where it exists as a natural nickel-iron alloy. In the Earth’s crust, nickel is more abundant in ferromagnesian rocks compared to silicic rocks. For instance, olivine-rich rocks have nickel concentrations 1000 times higher than granite, and gabbro has about 80 times more nickel than granite.
Nickel is a silver-white metal known for its excellent mechanical strength, ductility, heat resistance, and high chemical stability. It does not oxidize in the air, making it a crucial raw material for producing stainless steel, high-nickel alloy steel, and alloy structural steel.
Uses of Nickel:
- In the military manufacturing industry, nickel is extensively used in various sectors such as aircraft, radar systems, missiles, tanks, ships, spacecraft, and nuclear reactors.
- In civil industries, nickel is commonly processed into structural steel, acid-resistant steel, heat-resistant steel, and finds widespread applications in various mechanical manufacturing sectors.
- Nickel is also employed as ceramic pigments and corrosion-resistant coatings.
- Nickel-cobalt alloys serve as permanent magnetic materials and find wide applications in electronic remote control, atomic energy industry, and ultrasonic technology.
- In the chemical industry, nickel is frequently used as a hydrogenation catalyst.
In summary, due to its exceptional properties, nickel has become an indispensable metal for the development of modern aerospace, national defense industries, and the establishment of a high-level material and cultural life for humanity.
Currently, nickel laterite ores are mainly processed through direct smelting methods, which can be broadly categorized into two classes: wet and pyrometallurgical methods:
Wet Method 1: Primary oxidized nickel ore (high-pressure leaching with sulfuric acid) → Nickel sulfate (precipitated with hydrogen sulfide) → Nickel sulfide.
Wet Method 2: Primary oxidized nickel ore (reduction roasting) → Nickel-iron alloy structure in the ore (treated with ammonium carbonate solution) → Nickel hexammine complex (rotary kiln drying and calcination) → Nickel oxide powder (reduction reaction) → Metallic nickel.
Pyrometallurgical Method 1: Primary oxidized nickel ore (rotary kiln drying, electric furnace smelting) → Nickel-iron.
Pyrometallurgical Method 2: Primary oxidized nickel ore (sintering machine sintering, blast furnace smelting) → Nickel-iron alloy. Nickel mining