About Coal

Coal is a combustible, sedimentary, organic rock formed from ancient vegetation, which has been consolidated between other rock strata and transformed by the combined effects of microbial action, pressure and heat over a considerable time period. This process is referred to as 'coalification'.

Layered between other sedimentary rocks, coal is found in seams ranging from less than a millimetre in thickness to many metres.

Coal is composed mainly of carbon (50-98%), hydrogen (3-13%) and oxygen, and smaller amounts of nitrogen, sulfur and other elements. It also contains a little water and grains of inorganic matter that remain as a residue known as ash when coal is burnt.

Types of Coal Produced by Invercoal
The degree of change undergone by a coal as it matures from peat to anthracite – known as coalification – has an important bearing on its physical and chemical properties and is referred to as the ‘rank’ of the coal

Low rank coals, such as lignite and sub-bituminous coals are typically softer, friable materials with a dull, earthy appearance. They are characterized by high moisture levels and low carbon content, and therefore a low energy content.

Higher rank coals are generally harder and stronger and often have a black vitreous lustre. They contain more carbon, have lower moisture content, and produce more energy. Anthracite is at the top of the rank scale and has a correspondingly higher carbon and energy content and a lower level of moisture

Source: World Coal Institute

The types of coal mined by Invercoal are in the Higher Rank in the range of Hard Coals with high content of carbon, low volatiles and low sulfur as follows:

  • Low, Medium and High Volatile Coking Coal
  • Semi-anthracite
  • Anthracite

Invercoal Presently SOld Products

  • Semi-anthracite for Low Volatile PCI Coal
  • Injectable Anthracite for electric furnace
  • Charge Anthracite for electric furnace
  • Calcined Anthracite
  • Anthracite Filter Media for Municipal and industrial water tratmen systems

Uses of Invercoal´s Coal and Products

Coal has been largely used along the history and strongly in present days in many ways. Now with all the scientific and technological developments regarding coal usage, it has been found to produce clean natural gas, transportation fuel (coal liquefaction), and Hydrogen, besides the traditional uses of coal like clean power generation, Industrial Uses, Steel Manufacturing and Water Treatment with Filter Media, among others.

Main uses of coal in which Invercoal presently specializes are listed below:

Steel Manufacturing:

Coal is essential for iron and steel production; some 64% of steel production worldwide comes from iron made in blast furnaces which use coal. World crude steel production was 965 million tons in 2003, using around 543 Mt of coal.

A blast furnace uses iron ore, coke (made from specialist coking coals) and small quantities of limestone. Some furnaces use steam coal and semi-anthracite – known as pulverized coal injection or PCI – to achieve cost reduction since PCI is more affordable that coke.

Semi-anthracite mined by Invercoal has perfect characteristics for PCI coal, due to its low volatile, high carbon content and its high Calorific Value Semi-anthracite mined by Invercoal has perfect characteristics for PCI coal, due to its low volatile, high carbon content and its high Calorific Value

Coke is made from coking coals. Invercoal provides low, medium and high volatile coking coals that are mixed optimally in order to achieve high quality coke. The coking coal is crushed and washed. It is then ‘purified’ or ‘carbonized’ in a series of coke ovens, known as batteries. During this process, by-products are removed and coke is produced.

Low Volatile Coking Coal mined by Invercoal allows to produce a high quality coke due to its high Free Swelling Index (FSI) and low volatile, ash and sulfur content.

  • Pulverized Coal Injection (PCI) Coal

‘Pulverized coal injection’ (PCI) technology to be used allows coal to be injected directly into the blast furnace. A wide variety of coals can be used in PCI, including steam coal, and semi-anthracite.
PCI coal is crushed into a fine powder and injected into blast furnaces as a replacement for coke in the production of pig iron. PCI coal is injected through the injection nozzle near the base of the furnace.

The replacement ratio of PCI coal to coke varies according to the requirements of each blast furnace, however replacement ratios are continuing to improve in favor of low volatile PCI coal. Typically 1.0 ton of low volatile PCI coal can replace 1.5 tons of coking coal.
Low volatile PCI coal is increasingly sought by steel mills in preference to high volatile coal that has traditionally been used as PCI coal. Low volatile coal provides superior performance in the blast furnace due to its higher energy content.
Approximately 64% of steel production worldwide comes from iron made in blast furaces which use coal. (Source: World Coal Institute)
China leads growth in global steel production in an effort to meet its internal infrastructure requirements. China's crude steel production increased by 73% between 2000 and 2003 (Source: World Coal Institute).
Significant growth in steel production is also expected to occur in Brazil and India. Installed steel production capacity in Brazil is expected to increase from 34 million to 44 million tonnes per annum between 2004 and 2008. The country is expected to invest approximately US$7.4 billion over the same period (Source: Brazilian Iron and Steel Institute). Industry analysts anticipate India's crude steel production to double to nearly 70 million tonnes per annum by 2010 (Source: The Financial Express).

  • Injection and Charge Anthracite

These types of anthracite are used in electric furnaces. Injection Carbon may be produced from dry fine anthracite or pulverized anthracite. Anthracite for charge is produced from the R.O.M. anthracite, has a bigger size and is added directly into the furnace.

Anthracite is used to add carbon points in the furnace or in the ladle. Anthracite has proved to be a successful source of carbon or additional heat with the added advantage of minimal impact on the injector equipment.

  • Calcined Anthracite

The primary application of Calcined Anthracite is in steel mill ladles, melting, holding and even blast furnaces as recarburizer . It has also found to be used as the substitute of calcined petroleum coke in particular application because of its comparable quality and competitive price
Calcined Anthracite is produced when anthracite is calcined under the temperature of 1200-1400C in electric or vertical shaft furnaces to obtained a devolatized and partially graphitized product. Calcining is controlled to achieve specific characteristics.
Raw materials for Calcined Anthracite are selected carefully from Invercoal´s Anthracite Coal mines which are proven to have low ash and low sulfur content.

Water Treatment:

Filter media is highly used in the municipality water treatment industry.

Anthracite Filter Media placed on top of a bed of sand is the most effective way to increase the throughput and run times of a filter

Anthracite typically produces consistent improvements in turbidity removal because, in part, to more efficient solids loading. Low uniformity coefficient media also produces smaller changes in effluent turbidity during periods of peak influent turbidity.
Invercoal's anthracite filter media is produced from the highest quality anthracite available in Colombia to ensure the physical characteristics of hardness, durability and performance.