Development of an alkali-resistant coke
Using CRE-developed bulk test procedures, cokes containing deposited potassium carbonate were exposed to temperatures up to 1400 C in various nitrogen/carbon dioxide gas mixtures. It was established that the structural weakening of coke caused by potassium does take place at gas compositions containing less than 5-10% carbon dioxide. At higher carbon dioxide concentrations direct interaction is prevented and coke loses strength solely by catalytic gasification. Experiments on potassium vapour attack on coke of blast furnace size confirmed the deleterious effects of alkali on coke strength (albeit in inert conditions). In order to maximise the strength of coke in the bosh region of the furnace, an important step is to select coals of low alkali content in order to help reduce the alkali content loading to the furnace. There are also possibilities of increasing the alkali resistance of the coke by adding fine minerals to the coking charge or by including in blend formulation a selection procedure which gives consideration to preferred mineral compositions of coals. Improvements in alkali resistance are given by prior exposure to high temperatures and by the presence of carbon dioxide (particularly concentrations above 5-10%). Thus coke's effective alkali resistance in the blast furnace would be improved by maximisation of these conditions.
Bibliographic Reference: EUR 12652 EN (1990) 68 pp., MF, ECU 4, blow-up copy ECU 8.75
Record Number: 199010549 / Last updated on: 1994-12-01
Original language: en
Available languages: en