Ferronickel Submerged Arc Furnace 6.3MVA To 45MVA Reduction Furnace

I. Overview

The ferronickel submerged arc furnace (also known as a reduction furnace) is the core equipment specifically designed for smelting ferronickel alloy. This series covers capacities from 6.3 MVA to 45 MVA, encompassing medium, medium-large, and large ferronickel production units. Ferronickel is a key raw material for stainless steel production. The ferronickel furnace reduces nickel and iron oxides in laterite nickel ore to their metallic state using electrical energy, forming ferronickel alloy (FeNi).

This process is typically the core component of the RKEF (Rotary Kiln-Electric Furnace) process, offering advantages such as mature technology and stable product quality, and is particularly widely used in China and Southeast Asia. Large ferronickel SAF can reach 30–72 MVA.

• Capacity Range: 6.3 MVA, 12.5 MVA, 16.5 MVA, 25.5 MVA, 33 MVA, 40.5 MVA, 45 MVA

• Furnace Type:  Circular or Rectangular, Fixed, Low Smoke Hood

• Application: Ferronickel Alloy Smelting

NiCrMo structural steels containing 1%–4% nickel are well-suited for the automotive, locomotive, and machinery manufacturing industries due to their favorable tensile strength-to-weight ratio. In addition to these elements, wear-resistant structural steels also contain carbon. However, the most important nickel-containing steel grades and their largest consumers are stainless and heat-resistant special steels. For example, heat-resistant stainless steels such as Cr18Ni9Ti and Cr17Ni11Mo2 exhibit good hot workability and are widely used in machinery, medical equipment, national defense, and light industry.

Nickel has a slight graphitizing effect in cast iron, stabilizing pearlite and reducing ferrite content. Therefore, nickel in cast iron contributes to achieving a uniform and integrated structure with good properties. Adding small amounts of nickel (0.1%–1.0%) leads to the formation of fine pearlite, while higher nickel content results in martensitic and austenitic structures. Fine and stable pearlite gives cast iron good machinability and hardness. Consequently, nickel-containing cast iron parts are used in automotive manufacturing.
 

II. Working Principle

The working principle of the ferronickel SAF is based on submerged arc smelting technology. The electrodes operate deep beneath the charge layer, with the arc covered by the charge. The arc energy and resistance heat generated by current passing through the charge heat the material together, reducing nickel and iron oxides to their metallic state at high temperatures.

Main Reduction Reactions (Simplified):

Reducing Agent: Coke or semi-coke
Temperature: 1450–1700°C

Core Advantages of Submerged Arc Operation:

Electrodes immersed in charge, reducing heat loss

Improves thermal efficiency

Protects furnace lining from direct arc radiation
 

III. RKEF Process Flow

RKEF (Rotary Kiln-Electric Furnace) is currently the mainstream process technology for ferronickel production, featuring strong process adaptability and high nickel recovery rate. This process combines the ferronickel SAF with a rotary kiln to form a complete pyrometallurgical process flow.

Detailed Description of Each Stage

Nickel-iron alloys with low iron content, containing chromium, cobalt, and molybdenum, are generally referred to as Hastelloy corrosion-resistant nickel-based alloys when used as high-temperature alloys. Their tensile strength at 923°C reaches up to 233.24 MPa. Iron-nickel alloys containing 30%–90% nickel exhibit high magnetic permeability, making them suitable for the electrical and electronic industries—for example, the Climax alloy containing 30% nickel and 70% iron. An alloy composed of 80% nickel, 14% chromium, and 6% iron is a special corrosion-resistant spring material used in dental applications. Nickel is also used in coinage and in the battery industry.