As per GOST
For the purposes of clarity and avoidance of confusion, the comments below make use of Russian symbols given in the Table below:
Let us take, for example, the coal of Tr grade. The Russian symbols used imply the coal to be LEAN as to its grade composition, and RAW as to its granular composition (lump size can vary from 0-200 to 300 mm). It should be noted, however, that in this case the percentage composition of some specific grades should not be restricted. That may be the coal, consisting of 90% of large lumps and of 10% of dust coal, and vice versa. When the coal is marked as TPK (ТПК) , it means it being lean, sorted as per the lump size from 50 (40) to 200 .. 300 mm. The content of small (less than 50 mm) fragments should not exceed 15%.
There also exist grades with respectively substituted upper and lower size limits: e.g. when 100 mm is substituted by 80 mm, 50 mm by 40 mm, 25 mm by 20 mm, 13 mm by 10 mm and 6 mm by 5 (8) mm; combined grades: PK (ПК), KO (КО), OM (ОМ), MS (МС), providing the ratio between lower and upper limits of no more than 1:4, and grades OMSSH (ОМСШ), MSSH (МСШ) and SSH (СШ). The upper limit of 300 mm for the lump and raw coals applies only to open-pit mining enterprises. The specific coal grades as per the lump-size and content of fines and lumps of the upper limit are to be established by the standards of technical requirements in accordance with types of consumption.
Almost all grades except for coking ones G (Г), ZH (Ж), K (К), OS (ОС) can be used for the purposes of municipal and public utility services, and household. The coking coals of the grades mentioned above are quite deficient raw materials; when they happen to be assigned for the purposes of heat and power supply, such coals are used only in the form of tailings (middlings, cuttings) or when being rejected for coking for whatever reasons.
Coal properties differ with different grades. Their burning will naturally reveal such differences, which are to be known and taken into consideration when selecting fuels and combustion modes.
The organic (dry-and-ash-free) part of coals consists of volatile matters and fixed (coking) residue. Volatile matters make up 60% and more in brown coals and up to few percents in anthracites.
Classification of coals:
Lump size classification
Types of coals