Dry Processing of Iron Ore Beneficiation: Technological Developments and Industrial Practices

AKSA MAGNET
Jan 15
3 min read

1. Introduction

According to data from the World Steel Association, crude steel production has increased more than threefold, rising from 595 million tons in 1970 to 1,952 million tons in 2021. While a significant portion of this production is carried out by China, global steel production is expected to grow annually by 1–2% in the future.

In 2019, of the 1,875.3 million tons of crude steel produced worldwide, 70.8% was produced in blast furnaces and 5.9% through direct reduction processes. A total of 2,315.7 million tons of iron ore was used for this production. The most important iron ores are hematite (Fe₂O₃), magnetite (Fe₃O₄), and siderite (FeCO₃), containing up to 69.9%, 74.2%, and 48.2% iron, respectively. However, reserves of high-grade iron ores are gradually decreasing. Therefore, beneficiation of low-grade iron ores is becoming increasingly important.

2. Iron Ore Reserves and Lifetimes

According to 2019 data from the United States Geological Survey (USGS), global iron ore reserves are approximately 179 billion tons with an average iron content of 47.6%.

In terms of iron content, Australia (23 billion tons), Brazil (15 billion tons), and Russia (14 billion tons) are leading countries. Based on current production levels, the lifetime of known reserves is estimated at approximately 69.4 years. However, the gradual depletion of high-grade ores makes beneficiation of low-grade ores unavoidable.

3. Iron Ore Beneficiation Technologies

Iron ore beneficiation involves different processes depending on the iron content of the ore. High-grade hematite ores are generally processed through a simple “Crush–Grind–Screen–Sell” route, whereas magnetite ores require more complex processes. These include fine grinding, dense media separation (DMS), and low-intensity magnetic separation (LIMS).

Traditionally, iron ore beneficiation processes have been carried out as wet processes. However, due to water scarcity, wastewater management challenges, and environmental impacts, interest in dry beneficiation methods is increasing. For example, Vale has developed a dry magnetic separation process called FDMS (Fine Dry Magnetic Separation) using rare earth magnets. This process can increase the iron content of magnetite concentrate up to 68%.

4. Case Studies

4.1. Australia and South Africa

Major iron ore producers such as BHP Billiton, Rio Tinto, and Fortescue Metals Group directly ship high-grade ores while establishing beneficiation plants for low-grade ores. For instance, BHP Billiton plans to install a beneficiation line at the Jimblebar Mine to increase iron content. Similarly, Rio Tinto aims to produce high-quality iron ore by using dry screening and magnetic separation processes in the Gudai-Darri project in the Pilbara region.

4.2. Brazil

Vale is conducting extensive efforts to convert its production in Brazil from wet processes to dry processes. Under the S11D project, the company plans to beneficiate 200 million tons of iron ore using dry processes. In addition, new technologies such as dry magnetic separation and dry screening are being developed for fine ores.

5. Future Perspective

Dry iron ore beneficiation is becoming increasingly important in terms of water conservation, environmental sustainability, and waste management. Major mining companies, particularly Vale, are investing in dry beneficiation processes while increasing production capacities. This trend is expected to be adopted by iron ore producers on other continents as well.

In conclusion, dry beneficiation of iron ore stands out as an important alternative due to water scarcity and environmental concerns. Technological advancements and successful case studies support the wider adoption of this process in the future.

Dry Beneficiation of Iron Ore Using Dry Processing