The crystal structure of coke

[Amir1]

Hello guys.I have a question.What is the crystal structure of coke?I know that coke is made of carbon but I want to know that how are these carbons organized in coke?let me say that more clear.for example , graphite is made of carbon too and the carbons are organized in layers parallel together and are organized in a hexagonal crystal structure.how about coke?

[StringJunky]

 

The cokemaking process involves carbonization of coal to high temperatures (1100°C) in an oxygen deficient atmosphere in order to concentrate the carbon. The commercial cokemaking process can be broken down into two categories: a) By-product Cokemaking and b) Non-Recovery/Heat Recovery Cokemaking. A brief description of each coking process is presented here.

The majority of coke produced in the United States comes from wet-charge, by-product coke oven batteries (Figure 1). The entire cokemaking operation is comprised of the following steps: Before carbonization, the selected coals from specific mines are blended, pulverized, and oiled for proper bulk density control. The blended coal is charged into a number of slot type ovens wherein each oven shares a common heating flue with the adjacent oven. Coal is carbonized in a reducing atmosphere and the off-gas is collected and sent to the by-product plant where various by-products are recovered. Hence, this process is called by-product cokemaking.

 

http://www.steel.org/Making%20Steel/How%20Its%20Made/Processes/Processes%20Info/Coke%20Production%20For%20Blast%20Furnace%20Ironmaking.aspx

Coke is mechanically homogenised coal so I don't think it has a natural crystal structure.

Edited February 9, 2015 by StringJunky

[John Cuthber]

Coke is mechanically homogenised coal so I don't think it has a natural crystal structure.

There is more to it than the homogenisation.

Roasting to 1100 C drives out a lot of impurities and to some extent, allows the recrystallisation of the carbon.

 

Much of the carbon present will be in the form of tiny crystals of graphite.

[StringJunky]

There is more to it than the homogenisation.

Roasting to 1100 C drives out a lot of impurities and to some extent, allows the recrystallisation of the carbon.

 

Much of the carbon present will be in the form of tiny crystals of graphite.

OK. Thanks for the correction.

[Enthalpy]

"Parallel layers" must be an over-simplification for graphite. Since all available graphite is far from the theoretical density (commonly -10% or -20%, where pyrolytic graphite is the least bad), the order must be very loose. That's something not observed with other materials; for instance metals have the same density to ~0.1% whether single-crystal or polycrystaline, and so does silicon even if amorphous, so even tiny crystal must hardly explain graphite's abnormal density; I suspect the stacking of 2D layers to be very bad.

[studiot]

Greenwood & Earnshaw refer to "poorly formed graphite" for the structure of coke.

 

Wells gives more detail

 

 

The similarity of the X-ray photographs of the various types of 'amorphous carbon', ranging from lamp-black to coke to charcoal, suggested that all these materials are graphitic in character, being composed of small portions of the graphite structure but without the regular 3-dimensional periodicity characteristic of a crystal.

 

It should be noted that there are two full forms of the graphitic structure, with slightly different interplanar separations.

 

So the structure would appear to consist of crystallites, being small pieces of containing the regular hexagonal graphitic planes, but not fully aligned and linked in the third dimension; the crystallites being randomly oriented with respect to each other, like the grains in a metal.

[Amir1]

Thanks all guys.