Iron ore is a rock or mineral from which metallic iron can be extracted economically. It constitutes 5% of the earth’s crust. Viable forms of ore contain between 25% and 60% iron. Ore greater than 60% iron is known as natural ore or direct shipping ore, meaning it can be fed directly into iron-making blast furnaces.
Ninety-eight percent of iron ore mined goes into producing steel, the world’s most common metal. By definition, steel is the element iron (99%) combined with carbon (1%). The iron in iron ore comes from iron oxides found in deposits such as massive hematite (the most commonly mined), magnetite, titanomagnetite, and pisolitic ironstone.
Most major deposits can be found in sedimentary rocks created by chemical reactions between iron and oxygen in fresh and marine waters between one billion and three billion years ago. Earth’s waters contained a significant quantity of dissolved iron and almost no dissolved oxygen during that time. The deposits began to develop when the first photosynthetic organisms started releasing oxygen into the waters. That oxygen is combined with the dissolved iron to create hematite or magnetite.
Large amounts of the minerals landed on the seafloor and formed what came to be banded-iron formations, which are referred to as such because the iron minerals settled in alternating bands with silica and occasionally shale. These bands are remarkably ample in the U.S., Brazil, and Australia.
Other iron ore deposits formed as magmatic magnetite during ancient volcanic eruptions that released vast quantities of magnetite that later crystallized. Granite-linked deposits that require little post-processing for iron extraction have been found in locations such as Malaysia and Indonesia.
How Is Iron Ore Processed & Used?
Mining iron ore typically involves finding a fertile site, drilling and blasting the ore, and then transporting it to the primary crusher for processing. Crushed ore is sorted over screens and resized to different specifications (lump and refined products).
After the processing, a stacker builds a stockpile in the stockyards. Then, a reclaimer picks up the ore from the stockpiles and conveys it to train load-out facilities.
Today, the most common method for extracting iron from its ores after mining is coke smelting in a blast furnace at a steel plant. Hot air is pumped into the furnace at the bottom through perforations called tuyeres. This initiates some of the reactions for the smelting that becomes pure–molten iron production. The furnace also is initially charged with coke, limestone, and iron oxide to be reduced to pure iron.
Coke, a form of carbon, is produced by heating coal in the absence of air. It reacts with oxygen from the hot air blasted into the furnace to form carbon dioxide. The heat from this reaction is the main source of iron production in the blast furnace.
The very high temperature at the bottom of the furnace causes more coke to react with carbon dioxide and form carbon monoxide. The carbon monoxide then becomes the “reducing agent” for the iron by donating electrons to the oxide, converting it to pure iron and more carbon dioxide.
The limestone (calcium carbonate) added to the initial furnace charge reacts to the intense heat and gives calcium oxide, which reacts with other oxides in the rock. The resulting reaction products run down to the furnace’s bottom and form a molten layer called slag on top of the liquid iron.
The molten iron is tapped from the furnace’s bottom and run into sand molds to harden into a product is known as pig (cast) iron. The pig iron is then converted to steel by removing any other impurities and combining the molten iron with any other metals needed for the type of steel being produced.
The molten steel from the plant’s furnaces is passed through casters and made into slabs, billets, and blooms. These form the steel that can be further processed into finished products using cold and hot rolling procedures. Typically, the slabs are rolled to make flat finished products. The blooms become beams, girders, and many other structural shapes. The billets become rods and bars.
Steel products have extensive uses in wide-ranging industries such as ships, planes, trains, automobiles, construction, packaging, large home appliances, and heavy machinery.
Who Are the Biggest Iron Ore Producers?
The world’s five largest iron ore–producing countries are Australia, Brazil, China, India, and Russia.
As of 2020, the largest global iron ore—producing companies were:
- Vale (Brazil, 300 million tons). The largest exporter of iron ore and the Americas’ largest mining company with a reserve of nearly four billion tons, Vale produces 80% of Brazil’s iron ore.
- Rio Tinto (United Kingdom & Australia, 286 million tons). A leader in the exploration, exploitation, and processing of mineral resources, the company centers its iron ore operations in the Pilbara region of Australia, home to the world’s largest known iron ore reserves.
- BHP Group Limited (Australia, 248 million tons). The world’s largest mining company and a major exporter of iron ore, BHP likewise focuses its iron ore assets in Australia’s resource-fertile Pilbara region.
- Fortescue Metals Group Ltd (Australia, 204 million tons). Australia’s third-largest iron ore exporter has the Pilbara region’s most significant exploration territory, with 4.5 billion tons of iron ore resources in less than 15% of the total area of 50,000 square kilometers.
- Anglo American (the United Kingdom, 61 million tons). Centered in London, the mining business has two primary operations focused on iron ore production: the Minas-Rio operation in Brazil and the majority ownership of the Kumba project in South Africa.
What Are the Dust Issues in Iron Ore Production?
The mining and production of iron ore can create fugitive dust emissions at a processing plant during land clearing and ground excavation and from onsite equipment traffic. In addition, potential sources of fugitive dust during bulk material handling can include loading and unloading, ore crushing, stockpile erosion, and dust from conveyor systems.
The minerals in iron ore include silica dust, which can lead to lung irritation and disease if inhaled regularly. In addition, excess dust and material spillage can further accelerate wear on equipment such as cleaners, idlers, trackers, and ploughs and cause unplanned downtime and maintenance.
The dust also can potentially travel out to damage property and become an increasing hazard and nuisance for nearby communities.
How Can Benetech Help with Iron Ore Dust Control?
As leaders in safer, more efficient bulk material handling, Benetech specializes in the engineering, procurement, and construction solutions for the challenges that operators confront with specific bulk materials.
Proper dust control for mining and processing iron ore has a system that targets each source and cause of fugitive dust. Benetech’s patented MaxZone® Modular Skirtboard, and Belt Support System seals your iron ore load zone to reduce fugitive dust, prevent product loss and spillage, and improve material flow.
The system also can be retrofitted to accommodate and enhance an existing system as an economical solution to sealing and protecting your load zone. In addition, its modular design allows you to replace components without special permits or extended shutdowns, installation is simple and affordable, and no welding is required.
Components for dust control include:
- Sealing System with no-hassle clamps and seals on the sides of the load zone to contain dust and eliminate spillage
- MaxZone XN Externally Adjusted Internal Wearliner inside the skirtboard to protect the sealing system and extend the life and production of chute work
- Warrior Impact Bed with a stiff, rigid frame and soft rubber bars to cushion and absorb impact on the conveyor belt during loading
- Warrior Roll & Guide Support Bed with low-friction slider bars on the wing section and rollers in the center to create a seamless seal against load zone spillage and dust
- Simple Slide Idler for roller frames that slide into place close together without the need to remove adjacent idlers even in confined spaces, providing superior belt support with safe, easy maintenance
- Primary and Secondary Belt Cleaners (Scrapers) for resolving carryback issues
- Easy-Change Dust Curtain that interrupts airflow and lets the dust settle on the belt
- Unique Peaked Hood Design for greater containment of escaped material and less settling of dust
- Tailseal with skirting and strip rubber that creates a tight seal at the rear of the chute work
Benetech engineered advanced-flow transfer chutes further contribute to powerful dust control for iron ore. After evaluating what you need to control dust at your iron ore facility, we will design, fabricate, and install transfer chutes for your exact requirements, including transfer chutes for your transfer tower cascade conveyors and post-crusher load zones.
Our transfer chute designs are a key component of our patented InteliFlo® load chute with the adjustable J-Glide® discharge. InteliFlo’s design helps prevent the generation of dust rather than just passively trying to control it. Its distinctive round chute design replaces a traditional chute’s square corners, maximizing material flow while dramatically reducing build-up and spillage. Adjustable horizontal loading also works to ensure improved center loading of the belt.
Benetech solutions for you result in less dust and spillage, longer life of conveyors and other equipment, reduced downtime and maintenance, and greater plant safety.
The Ally to Your Iron Ore Processing Plant
Here at Benetech, we dedicate our greatest resources to resolving your daily challenges in bulk material handling. To discuss how you can reinforce a safer, more productive iron ore facility, contact us at (630) 844-1300 to speak with a specialist.
Posted in Dust Control