Objective
Sulphur and nitrogen oxide emission into the atmosphere and the associated problem of acid rain are currently a subject of major concern. Within the steel industry, the main source of emission is grate-type iron-ore sintering plant. The aim of the project is to quantify the effects of certain production parameters which will become very important in the future (bed thickness, partial recycling of fumes, super-reducible sinters) and to optimize them with a view to striking the best possible balance between considerations of production, energy-saving and environmental protection. It is also hoped to obtain better insight into the mechanisms by which pollutants are formed during the sintering process and to locate more accurately the part of the strand where emission is highest. The final aim of the study is of course to reduce pollutant emission as far as possible at source and/or to concentrate emissions into restricted areas to facilitate their capture and subsequent treatment.
The experiments demonstrated that the operator of a sintering plant who operates at high degree of productivity and quality has very little latitude at his disposal at the level of the production process enabling him to reduce the emissions of NOx and SO2 into the atmosphere. As concerns the emission of sulphur oxide, the sulphur content of the coke, the specific coke consumption and the basicity of the mix constitute the major parameters of influence. In the case of NOx emission, there is much less room to manoeuver. Certain measures taken to reduce SO2 emissions may even have an adverse effect on the emissions of NOx. A priori evidence seems to indicate that the partial recycling of exhaust gases from sintering and the addition to the mix of such extremely hydrated ores as goethite offer the most promising possibilities of reaching a solution for a modern sintering plant. Whatever the choice, the potential for reducing SO2 and NOx emissions at source is poor (it could be estimated at around 20 - 40%), and such methods are often implemented to the detriment of productivity and of the quality of the sinter.
All trials will be carried out in an experimental sintering unit.
The tests will mainly comprise:
- a comparison of conventional and modified sintering techniques in respect of SOx and NOx emission;
- more systematic study of the effects of the operating parameters which prove to be the most important and optimization of these parameters for production and environmental protection purposes;
- location of the zones of highest emission of acid gaseous pollutants as a function of the operating conditions.
Topic(s)
Call for proposal
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4000 Liege
Belgium