The CQPA calculation consists of the following steps:
This recalculation ensures the same type of input data for mineral evaluation by CQPA and Raask methods.
The percentages of minerals in coal samples 1 5 were evaluated using the methods of Raask (method I) and CQPA (method II) described above.
For our samples (subbituminous rank) with somewhat different proportion of quartz/kaolinite and higher content of pyrite, the results calculated by Raask's method are less satisfactory than that obtained by CQPA method (see e.g.
where [c.sub.i,cal] is the concentration of the i-th oxide obtained from the calculated mineral contents by method I (Raask) or method II (CQPA); [c.sub.iexp] is the concentration of the i-th oxide from the comparative chemical analysis (CHA).
In this paper, the CQPA (Klika et al., 1986) and Raask's methods are tested and compared for quantitative determination of minerals in the Czech coals.