Metallurgical Coke

High temperature metallurgical coke is produced by the heating of bituminous coking coals in industrial coke ovens. When bituminous caking coals are heated in the absence of air, they begin to soften at a temperature of around 400 °C exhibiting a plastic like behavior. At higher temperatures the plastic mass begins to fuse and the trapped volatile gases cause the mass to swell. As carburization is completed at a temperature of around 1100 °C, most of the volatile matter is expelled and the mass again resolidifies to a porous solid fuel that has a much higher carbon content and less impurities than that of the contributing coals. The extent of the swelling is a function of the rank and volatile matter content of the coal. The resulting coke is a hard, finely cellular, carbonaceous mass that can be used as both fuels in foundries and other industries and as a reducing agent for the smelting of iron ore to pig iron and other metal ores in the production of ferro alloys.
Most metallurgical cokes are produced in modern by-product coke ovens which capture the secondary gas and tars from the distillation process to reuse as supplemental fuels, or in some case chemical feedstocks. Metallurgical cokes can be classified into two main types depending upon their production and intended industrial use.

Furnace coke is charged into a blast furnace for the smelting of iron or other ores.   The majority of furnace coke produced is employed in the steel industry.  Furnace coke size ranges from 1 inch to 4 inch has high coke strength and low reactivity.  High temperature furnace coke accounts for over 90% of the US domestic coke production.

Foundry coke is used for the melting of pig iron or scrap iron in large industrial cupolas for the production of cast irons.  The size of foundry coke is normally 4 inches and larger, low porosity and of high strength in order to support the heavy layers of iron. Less than 10% of the US metallurgical coke production is foundry coke.  Most of the foundry coke employed in the US is imported from China.

McCreath Laboratories will employ both ASTM and ISO standard methods in the analysis of metallurgical coke.  The methods are continually verified thru the use of certified reference materials.  Typical coal analysis performed are as follows:

TestInstrumentReference Method
Total MoistureAir-Dry OvenASTM D3302
Ash ContentMuffle/TGAASTM D3174 / D7582
Volatile Matter ContentFurnace/TGAASTM D3175 / D7582
Sulfur ContentLECO SC832ASTM D4239
Calorific ValueLECO AC500ASTM D5865
Carbon, Hydrogen, NitrogenLECO CHN828ASTM D5373
Minerals in AshThermo ICAP / WDXRFASTM D6349 / D4326
Tumbler TestASTM TumblerASTM D3402
ASG/TSG & PorosityPhysical TestASTM D167
Drop Shatter TestShatter ApparatusASTM D3038
Sieve Analysis SievesASTM D293

For more information on the analysis of metallurgical coke, contact us.