Facts about carbonisation

Coking in horizontal chamber ovens

Till date, coke has been produced mainly from coals with a content of volatile matters in the range of 20 % to 28 % and good coking properties. If such so-called "self-coking" coals are available, blast furnace coke or foundry coke with the required quality characteristics can be produced in top-charged horizontal ovens.

In this case, the possibility of using high-volatile coals and in particular coals with low-caking properties is very restricted.

Numerous efforts have been made during the last 30 years to enlarge the range of cokable coal taking into account the optimization of coke output and quality.

Moreover, it became evident that the conventional chamber coking method still holds considerable possibilities of further development.

For decades, coals with a content of volatile matter in the range of 32% to 36% (waf) were mined and carbonized in the Saar area, Germany.

Although these high-volatile coals have fair or even good coking properties, they are less suited for making blast furnace coke than classical coking coals.


Because of their high content of volatile matter, the loss of substance in form of gas and tar during carbonization is too high which creates internal tensions in the coke.


These tensions cause a susceptibility to crack and break. Early tests in the Research Centre proved that the mechanical coke strength is a function of coal density in the coke oven.


A stamp charged coke oven plant differs from a conventional top charged coke oven plant:

  • in the coal blend used
  • the preparation of the charge coal blend and
  • in the way of oven charging.

In all other aspects, a stamp charged coke oven plant is equal to a top charged coke oven plant.

Early tests in the Saarberg Research Centre proved that the mechanical coke strength is a function of coal density in the coke oven.

Because the charge density is such a important factor, how could a high density be achieved?

A Stamp Charged oven filling is characterised by the highest charge density of all pre-carbonisation technologies. By using Stamp Charge Technology, densities of 1.15t/m³ or even beyond can be achieved



Increase in production of Blast Furnace Coke

  • Increasing in mechanical strength parameter M25
  • Decrease in the abrasion value M10