Fragmentation, coal

Since liquid sulfur dioxide boils at -10.2°C the extraction can be conducted at atmospheric conditions. The liquid sulfurdioxide is obtained by cooling the gas from the cylinder using a Dry Ice acetone bath. When a coal liquid (usually in a waxy state) is treated with liquid sulfur dioxide, the insolubles remain with the minerals and the coal fragments as a solid residue. TheS02 Solu-bles are separated from the insolubles by filtration. The filtrate is... 

His measurements were made on "bulk" coal fragments extracted from the vicinity of pyrite particles. Electron-optical methods, though, can make such measurements in situ and have better spatial resolution than his bulk methods allowed. 

Our previous studies with model compound solvents indicated that higher boiling products can be produced via dimerization by coupling of aromatic methyl groups and by alkylation of the solvent by light coal fragments. 

Coal fragments, when heated in the absence of oxygen, yield coal tar, which contains many aromatic hydrocarbons and their derivatives. Consequently, coal is used as a raw material for other chemicals. 

Numerical modelling of outbursts requires the quantification of a number of processes and factors. These include gas adsorption and desorption, coal deformation and failure, coal fragmentation, gas dynamics and transport of outburst coal (particle flow). 

Equation (6) can be used as the source term in the mass balance and momentum equations to calculate gas flux and drag force acting on the coal fragments. 

The drag force (Ergun, 1952) of the gas on the coal fragments (assumed to be spherical) is given... 

According to the recommended protocol, large objects such as rocks, metal, glass, wood, coal fragments, and other miscellaneous debris were noted in the field notebook and were removed from the core samples prior to homogenization. Only one sample out of 140 was free of miscellaneous debris, and coal tar was most likely present in all samples. Material heterogeneity complicates sampling and analysis. Furthermore, extreme contaminant concentration levels can occur at the micro and macro physical scales, for example, with coal tar. 

Loose coal Coal fragments larger in size than coal dust. 

In the first stage of coal liquefaction, finely-crushed coal (particle size <0.1 mm) is slurried with a solvent, to render the coal flowable and pumpable. The choice of solvent is particularly important, since it must be suitable to stabilize the coal fragments and to dissolve the smaller disintegrated molecular moieties. Due to their similarity in chemical nature, coal-derived oils are particularly efficient. Anthracene oil from coal-tar processing was therefore preferred as a solvent, when coal hydrogenation was being developed. 

To achieve high solubility, it is necessary to saturate the coal fragments with hydrogen, for which only the hydroaromatic tetralin is suitable, in contrast to naphthalene and dodecane. As an example, the possible reaction of 1-phenan-threne-2-pyrene-ethane, a coal fragment model, with tetralin is shown overleaf. 

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