コークス中の窒素定量におけるケルダール法とジューマ法の比較検討

抄録

The establishment of an accurate analytical method of nitrogen in coke has recently become important in connection with the reduction of nitrogen oxides (NO_x) in flue gas from iron ore sintering plants.
The wet method (Kjeldahl method) and dry one (Dumas' method) have been widely used for the determination of nitrogen in coke.
In a recent paper, however, it was reported that the difference of analytical values was observed between Kjeldahl method and Dumas' method on the analysis of nitrogen in coke and the former has generally given lower values.
Therefore, the authors carried out experiments to confirm this point and also to clarify the reason of the difference between the two methods by using various coals, cokes, and organic reagents.
As a result, the following points became clear.
(1) No nitrogen was detected in the insoluble residue after the cokes had been treated by Kjeldahl method. Therefore, the reason why the wet method gives lower values can not be attributed to the dissolution method of samples.
(2) The reason can be ascribed to the existence of nitrogenous radicals which are contained in coal (raw material of coke) and will not easily change into ammonia.
(3) Only bituminous coal and coke produced from the coal showed considerably large difference compared with any other coal and coke.
(4) Bitiminous coal contains much nitrogenous radicals in comparison with other kinds of coals.