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Hot Briquetted Iron
What is Hot Briquetted Iron (HBI) and How Is It Used By The Steel Industry
What is HBI?
According to the International Iron Metallics Association, “Hot Briquetted Iron (HBI) is a premium form of Direct Reduced Iron (DRI) that has been compacted at a temperature greater than 650° C at time of compaction and has a density greater than 5000 kilograms per cubic meter (5000 kg/m3)”.
“DRI is a metallic material produced from iron oxide fines or iron oxide pellets and/or lump ores that have been reduced (oxygen removed) without reaching the melting point of iron.”
“HBI is a premium quality, high density steel industry raw material containing 90-94% total iron (Fe) in a nearly pure form, which is used in electric arc furnace (EAF) and basic oxygen furnace (BOF) steelmaking, blast furnace (BF) ironmaking, and foundry applications.”
Typical Analysis for HBI
|Fe (Total)||90.0 – 94.0|
|Fe (Metallic)||83.0 to 88.0|
|C||0.8 to 1.7|
|P2 05||0.02 to 0.11|
|S||0.003 to 0.03|
|Gangue||1.95 to 5.1|
The Market For Iron Based Metallics
When people think of raw materials for steelmaking, most immediately think of iron ore and metallurgical coal, only a few “in-the-know” think of steel scrap. Contrary to conventional wisdom however, all steel producers, whether they run electric arc furnaces (EAF), blast furnaces or basic oxygen furnaces (BOF), use steel scrap to produce steel.
World Steel Dynamics (WSD) in their 2011 World Crude Steel Forecast, report that between 2011 and 2020, the requirements for obsolete scrap for steelmaking may grow faster than the obsolete scrap reservoir. They further state that this imbalance may lead to a variety of consequences for the price of scrap, including: more frequent ‘price spikes’; increased demand for scrap substitutes; higher on average prices for steel scrap.
WSD also report that scrap consumption by the world steel industry was 339mm tonnes in 2011. By 2015 global scrap requirement is forecast to be 376 mm tonnes, which is an increase of 10.91% over the next four years. WSD expect the global scrap market may be tightest in 2020 when demand is expected to reach 481mm tonnes.
The International Iron Metallics Association (IIMA) report that there are already 26 countries with some form of restriction on steel scrap exports, as it is seen by many nations as a strategic resource with a finite supply; restrictions range from outright bans on exports to increased taxation on scrap exports.
Largely due to limited supply of this valuable urban resource, the scrap price has increased by 385% since 2001. In addition, scrap quality is declining because of the rising copper content in scrap steel. Steel is the most recycled material on earth. Copper content increases each time the material is recycled and currently there is no economic way to remove it.
The raw material for EAFs is almost 100% scrap, where blast furnaces and BOFs use 25 -35% scrap.
60% of North American steel is manufactured in EAFs and this method of production is growing around the world at about 1.5% per year.
With a looming shortage of a strategic raw material, steel makers everywhere are looking to alternatives to steel scrap. Blast furnace operators have more choices but iron ore cannot be used in EAFs as the process involves shorting an electric current through a metallic product rather than the reduction of an oxide as in a blast furnace.
Thus EAF operators require metallic raw materials and will be negatively impacted by any shortage of scrap steel.
HBI is complementary and a viable metallic alternative to scrap steel. Worldwide consumption of HBI is expected to double from 68 million tonnes in 2010 to 130 million tonnes in 2020.
How HBI is Consumed by the Steel Industry
HBI Use in EAFs
As HBI is a manufactured product with guaranteed specifications/chemistry, this allows steel makers to produce grades of steel not possible with scrap charges alone
For the EAF operator, the benefits are:
- Well defined chemical composition
- Well defined physical properties
- Can be used in both long and short arc furnaces
- Can be used in both AC and DC furnaces
- Lower residual content than scrap
- Can be stored outdoors in bulk
- Can be used in continuous feed operations
- Easily moved on conveyor belts
- Free flowing from bins
- Controlled carbon content
- Useful in slag foaming
- Controlled boil rinses nitrogen from the steel bath
For the Basic Oxygen Furnace operator, the benefits are:
- HBI provides an optimal charge due to:
- Low levels of residual elements
- Bulk density is higher than any type of scrap
- Same metallic yield as hot metal
- More predictable mass and heat balances
- HBI is an excellent trim coolant due to:
- Free flowing from overhead bins
- Well defined physical and chemical properties
- Maintains steel bath composition
- Rapid penetration of slag
- Reduces slag volume when used instead of fluxes
- Other advantages
- Protects furnace bottom by feeding charge pad before scrap charge resulting in less refractory damage
- Can be fed into charge pan to adjust final weight to avoid charge delays.
For the Blast Furnace operator the benefits are:
- Increased productivity as each 10% increase in burden metallization increase production by about 8%
- Decreased coke use. Each 10% increase in burden metallization will decrease coke rate by 7%
- Decreased CO2 emissions
- Compatible with injected fuels and oxygen
- Increased hot metal production rate
- Decreases energy requirements