Granulated Pig Iron (GPI)
What is GPI?
From time to time the supply of hot metal from a blast furnace may exceed the demands of the steel plant, for example due to problems further downstream. In most integrated steel mills, the blast furnace plants are not equipped with pig casters, meaning that the excess hot metal has to be cast into an open air sand pit, a process known as “pooling” or “beaching.” The ensuing dust and fumes constitute an environmental hazard and the resultant pool or beach iron takes a long time to solidify before it can be crushed into usable material.
Granulation of the excess hot metal is a process that deals with these issues and produces a by-product – granulated pig iron (GPI) – that can readily be used internally, for example as BOF coolant, or sold to third parties as feedstock for electric arc furnaces, cupolas and induction furnaces.
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Granulation process
The granulation process has four principal steps:
- control of the flow of hot metal to the granulator
- granulation by formation of liquid iron droplets, followed by rapid quenching in water
- discharge of solidified and cooled particles (GPI)
- dewatering and transport to storage.
The diagram compares the sandpit casting and granulation routes for dealing with excess hot metal.
Granshot® process of IIMA member UHT Uvån Hagfors Teknologi
Uses and benefits
To read more about GPI uses and its benefits for EAF steelmaking, please see our fact sheet:
Composition and characteristics of GPI
Shipping and handling of GPI
Granulated Pig Iron resources
Pig Iron: Guide for Transporting and Handling at Terminals
Use of Granulated Pig Iron (GPI) in the Electric Arc Furnace (EAF) for Steelmaking
More information on GPI
Read more about GPI’s uses and its benefits for EAF steelmaking in this fact sheet:
OBM production
Find out more information on how OBMs are produced.
Images courtesy of Uvån Hagfors Teknologi AB
Fact sheets on ore-based metallics
What are Ore-Based Metallics?
An overview of Ore-Based Metallics (OBMs), types, typical benefits in use and general specifications.
Use and Benefits of Ore-Based Metallics
A more detailed coverage of the benefits of using OBMs in EAF steelmaking.
Use of Hot Briquetted Iron (HBI) in the Electric Arc Furnace (EAF) for Steelmaking
Background to and advantages of use of HBI in the EAF and general characteristics.
Use of Hot Briquetted Iron (HBI) in the Basic Oxygen Furnace (BOF) for Steelmaking
Background to and advantages of use of HBI in the BOF and general characteristics.
Use of Hot Briquetted Iron (HBI) in the Blast Furnace (BF) for Hot Metal Production
Background to and reasons for use of HBI in the blast furnace and general characteristics.
Use of Direct Reduced Iron (DRI) in the Electric Arc Furnace (EAF) for Steelmaking
Background to and advantages of use of DRI in the EAF and general characteristics.
Use of Basic Pig Iron in the Electric Arc Furnace (EAF) for Steelmaking
Background to and advantages of use of pig iron in the EAF and general characteristics.
Use of Granulated Pig Iron (GPI) in the Electric Arc Furnace (EAF) for Steelmaking
Background to and advantages of use of GPI in the EAF and general characteristics.
Use of High Purity Pig Iron for Foundries Producing Ductile Iron Castings
Background to and benefits of using HPPI in production of ductile iron castings and general characteristics.
Use of Foundry Pig Iron in Grey Iron Castings
Background to and benefits of using Foundry Pig Iron in production of grey iron castings and general characteristics.
Relevance of Iron Ore to OBMs
Basic information about iron ore and its relevance to production of ore-based metallics.
Value-in-Use of Ore Based Metallics (OBMs) in EAF Steelmaking
An overview of the value-in-use concept and IIMA's model
Types of OBMs
Direct Reduced Iron (DRI)
DRI is the product of the direct reduction of iron ore in the solid state by carbon monoxide and hydrogen derived from natural gas or coal.
More about DRIHot Briquetted Iron (HBI)
HBI is a premium form of DRI that has been compacted at high temperature making it less reactive.
More about HBIPig Iron
Pig iron is the product of smelting iron ore (also ilmenite) with a high-carbon fuel and reductant such as coke, usually with limestone as a flux.
More about Pig IronGranulated Pig Iron (GPI)
Granulating excess pig iron produces a product GPI which can be used as BOF coolant or as feedstock for electric arc furnaces, cupolas and induction furnaces.
More about GPI