Metallurgical Coke Types offered by IGR:
IGR COKE BREEZE (0 – 10 MM)
IGR NUT COKE (10 – 25 MM)
IGR BLAST FURNACE COKE (30 – 90 MM)
IGR FOUNDRY COKE (90 – 150 MM)
Metallurgical Coke
The quality of the constituent coals determines the quality of the resulting coke. Good quality metallurgical coke is generally made from carbonization of good quality coking coals. Coking coals are defined as those coals that on carbonization pass through softening, swelling, and re-solidification to metallurgical coke. High quality coals produce coke that has the highest stability and CSR (coke strength after reactivity) to support the blast furnace and allow maximum production.
IGR metallurgical coke is manufactured through destructive distillation of a blend of selected high-grade metallurgical coal. This carbonisation of coal occurs at 1,100 0 C. Coking coals upon carbonisation go through softening, swelling and re- solidification to form coke.
IGR has access to high quality metallurgical coke from China, Russia and USA. IGR manages the entire supply chain – procurement ex-factory, on-road transportation, port handling, financing and storage. Our supplies are authenticated by independent assayers and the entire loading process is overseen by our inspectors at the loading regions.
One important consideration in selecting a coal blend is that it should not exert high coke oven wall pressure and should contract sufficiently to allow the coke to be pushed from the oven. The properties of coke and coke oven pushing performance are influenced by the following: coal quality, rank of coal, petrographic, chemical and rheologic characteristics of coal, particle size, moisture content, bulk density, weathering of coal, coking temperature and coking rate, soaking time, quenching practice, and coke handling. Coke quality variability is low if all these factors are controlled. The technical team at IGR have proven experience at metallurgical coke manufacturing and are amongst the top producers in the coke producing regions around the world.
Metallurgical Coke Types offered by IGR:
IGR COKE BREEZE (0 – 10 MM)
IGR NUT COKE (10 – 25 MM)
IGR BLAST FURNACE COKE (30 – 90 MM)
IGR FOUNDRY COKE (90 – 150 MM)
The quality of the constituent coals determines the quality of the resulting coke. Good quality metallurgical coke is generally made from carbonization of good quality coking coals. Coking coals are defined as those coals that on carbonization pass through softening, swelling, and re-solidification to metallurgical coke. High quality coals produce coke that has the highest stability and CSR (coke strength after reactivity) to support the blast furnace and allow maximum production.
IGR metallurgical coke is manufactured through destructive distillation of a blend of selected high-grade metallurgical coal. This carbonisation of coal occurs at 1,100 0 C. Coking coals upon carbonisation go through softening, swelling and re- solidification to form coke.
IGR has access to high quality metallurgical coke from China, Russia and USA. IGR manages the entire supply chain – procurement ex-factory, on-road transportation, port handling, financing and storage. Our supplies are authenticated by independent assayers and the entire loading process is overseen by our inspectors at the loading regions.
One important consideration in selecting a coal blend is that it should not exert high coke oven wall pressure and should contract sufficiently to allow the coke to be pushed from the oven. The properties of coke and coke oven pushing performance are influenced by the following: coal quality, rank of coal, petrographic, chemical and rheologic characteristics of coal, particle size, moisture content, bulk density, weathering of coal, coking temperature and coking rate, soaking time, quenching practice, and coke handling. Coke quality variability is low if all these factors are controlled. The technical team at IGR have proven experience at metallurgical coke manufacturing and are amongst the top producers in the coke producing regions around the world.
Coke manufacturing
The coal-to-coke transformation takes place as follows:
The heat is transferred from the heated brick walls into the coal charge. From about 375°C to 475°C, the coal decomposes to form plastic layers near each wall. At about 475°C to 600°C, there is a marked evolution of tar, and aromatic hydrocarbon compounds, followed by re-solidification of the plastic mass into semi-coke. At 600°C to 1100°C, the coke stabilization phase begins. This is characterized by contraction of coke mass, structural development of coke and final hydrogen evolution. During the plastic stage, the plastic layers move from each wall towards the centre of the oven trapping the liberated gas and creating in gas pressure build up which is transferred to the heating wall. Once, the plastic layers have met at the centre of the oven, the entire mass has been carbonized. The incandescent coke mass is pushed from the oven and is wet or dry quenched prior to its shipment to the blast furnace.
The water content in coke is practically zero at the end of the coking process, but it is often water quenched so that it can be transported to the blast furnaces. The porous structure of coke absorbs some water, usually 3-6% of its mass. In some of the coke plants dry quenching of coke is practiced.
Blast furnace coke has three major roles in iron making process: thermal, chemical and physical. The thermal role of blast furnace coke is being a source of fuel which provides the heat needed to melt iron and slag and for endothermic reactions inside the iron making blast furnace. The chemical role of blast furnace coke is producing and regenerating the reducing gases which are needed to reduce iron oxides; it’s also carburizing molten iron. The physical role of blast furnace coke is supporting mechanically the charge column and the permeable bed below the cohesive zone.
Metallurgical coke properties
Blast Furnace (“BF”) coke has a porous, open morphology and in some cases, it may appear glassy. BF coke has hardly any volatile content; however, the ash constituents, which were the part of the original feed coal remains entrapped in the resultant BF coke. The bulk density of the metallurgical coke is typically around 0.78.
High quality coke is characterized by a definite set of physical and chemical properties that can vary with in narrow limits. The coke properties can be grouped into following two groups: a) Physical properties and b) Chemical properties.
Physical properties:
Measurement of physical properties aids in determining coke behaviour both inside and outside the blast furnace. The physical properties are given below.
Mean coke size – sizing the coke over a specified series of screens.
Coke reactivity index (CRI) – It is measured by a laboratory test designed to simulate the loss of coke through reaction in the reducing atmosphere, as the coke makes its way down the blast furnace. Coke is heated up to 950 0C in an inert atmosphere and held at that temperature in an atmosphere of CO2. The coke is cooled down under the inert atmosphere and the loss in weight expressed as a percentage is the CRI value of the coke. CRI measures the ability of coke to withstand breakage at room temperature and reflects coke behaviour outside the blast furnace and in the upper part of the blast furnace.
Coke strength after reaction (CSR) – This gives an indication of the strength of coke after being exposed to the reducing atmosphere of the blast furnace. Coke, after exposure to the high temperature and CO2 atmosphere of the coke reactivity test, is subjected to a tumbler test to determine the CSR. CSR measures the potential of the coke to break into smaller size under a high temperature CO/CO2 environment that exists throughout the lower two-thirds of the blast furnace.
Chemical properties:
The most important chemical properties are moisture, fixed carbon, ash, sulphur, phosphorus, and alkalis. Fixed carbon is the fuel portion of the coke; the higher the fixed carbon, the higher the thermal value of coke. The other components such as moisture, ash, sulphur, phosphorus, and alkalis are undesirable as they have adverse effects on energy requirements, blast furnace operation, hot metal quality, and/or refractory lining.
Uses of Met coke
Besides being used in blast furnace, sinter plant, steel making furnaces and ferro – alloy production, metallurgical coke has many more applications. It is used where a tough and resilient, high quality wearing carbon is needed. Met coke’s applications include for example: friction materials, conductive flooring, foundry coatings, corrosion materials, foundry carbon raiser, reducing agents, drilling applications, ceramic packing media, heat-treatment, oxygen exclusion and electrolytic processes. Met coke can also be used as a filler coke for the poly-granular carbon products.
IGR metallurgical coke is traded for the following categories:
- IGR COKE BREEZE (0 – 10 MM)
- IGR NUT COKE (10 – 25 MM)
- IGR BLAST FURNACE COKE (30 – 90 MM)
- IGR FOUNDRY COKE (90 – 150 MM)
Note to Size Specification and Content Specification Parameters:
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- The specification parameters are indicative and generalized. Our factories are able to deliver customer aligned specifications.
- IGR undertakes to ensure that all Blast Furnace Coke supplied under the Contract to Supply to our Principal complies with the specifications outlined above.
- All costs associated with and resulting from the rejection of Blast Furnace Coke, which fails to comply with the specifications outlined above shall be borne by IGR.
IGR warrants that we are sufficiently experienced, capable and qualified to supply metallurgical coke of various sizes and quantities in accordance with the Supply Contract and Purchase Orders raised by our Principals.