Study On Energy Saving And Environmental Protection In Iron Ore Sintering Process

The steel industry is a big energy consumption and environmental pollution, and the sinteringproduction is an important link in steel production process. and in recent years, with thedevelopment of iron and steel production capacity continues to expand, the sintering industrygained a rapid development of hitherto unknown. The energy consumption and environmentalpollution problems in sintering process is becoming more and more serious, and it has become abottleneck of the sustainable development of iron and steel enterprises, drawing attention of thesociety.In this paper, on the basis of literature research, aimed at the need of the WISCO production,several energy and environmental issues of concern in sintering process were studied in detail. Inthe aspect of energy saving, mainly from the reduction of solid fuel consumption, studied onimprove the sintering mixture granulation performance of WISCO; The flux and the fuel dividedadding technology research; Study on leakage rate of sintering system test new technology andthe inhibition of edge effect of sintering machine; In the aspect of environmental protection,starting from the sintering pollutant control，studied on the decrease of SO₂emission in sinteringflue gas.Through the research of sintering mixture granulation performance, the WISCO common ironore physicochemical properties, assimilation and granulation properties were studied, the resultsshowed that in all iron ore, Canada concentrate （Hereinafter referred to as Canada fines） has thehighest grade, and lower silicon, aluminum and impurity content, but its size, hydrophilism andassimilation were very poor, so the granulation performance was very poor. In order to furtherunderstand the effect of Canada fines ratio on permeability, sintering indexes and sinter mineralcomposition, the sintering test of Canada fines proportion were carried on. The results showedthat, with the increase of the Canada fines proportion, the sintering mixture granulationperformance becomes worse, the permeability of the mixture and the average size showed adecreasing trend, and In the test conditions, When the Canada fines ratio is more than18%, thegranulation performance significantly worse, sintering utilization coefficient and the drumstrength decreased significantly, fuel consumption rise. Conclude from this: strengthengranulation is the key of improving sinter quality and reducing fuel consumption in WISCO. Onthe basis of this result, the comprehensive laboratory test and study on mathematical model ofDEM are carried. This paper proposed a series of technical measures to increase Canada finesratio, ensure the granulating effect and sinter yield and quality, and reduce fuel consumption,including optimizing ore proportioning, addition of RB organic binder and selection ofappropriate granulation parameters, and Canada fines ratio finally is up to32%.Through the study of flux and fuel divided adding technology showed that the process of fluxand fuel divided adding can effectively improve the yield and quality of sinter, reduction of solid fuel consumption obviously. And in WISCO raw material conditions, the ideal divided addingsolution for: Lime with the outside ratio of65%⁸0%, and anthracite with around75%in theoutside proportion. Through microscopic and SEM observation of sinter by flux and fuel dividedadding process found that the contents of SFCA and primary hematite increased, residual fluxsubstances and silicate glass phases decreased and the tiny-needle-shaped SFCA intertwinedwith each other and embraced primary hematite particles, so the rationalization of this process isvalidated with microscopic structure.In the study of test technology of the leakage rate of sintering system, a new method wasproposed. In this method, the steam generated by water in mixture was first considered in thecalculation of exhaust volume. The measuring method has the advantages of simple and easy andsmall deviation. Two sintering machines for production site was tested in WISCO, the result issatisfied. In the study of inhibition of edge effect of sintering machine, a new type of trolleybaffle was designed. The new trolley baffle was added two heaves based on the original slabbedconstruction, the height of heaves are designed according to the shrinkage of sinter layer ofWISCO. Industrial tests showed that the leakage rate of sintering system dropped about3percentage points, the air volume in the whole width direction and sintering machine tail "redbeds" were balanced, so the edge effect of the sintering machine was inhibited effectively.In the aspect of control of sintering waste gas SO₂, a new technology of reducing SO₂emission in sintering flue gas is presented. Unlike other sintering flue gas desulfurizationprocesses, this process is that the SO₂gas generated in the sintering process was transferred todust by adding a substance in sintering material, and then the dust returned to the raw materialsafter soaked and filtered to remove sulfur and alkali metals, so this process belongs to"process-control", not the usual "end-control". In this paper, three methods were proposed todispose the dusts. They are discarding, filtration and a combination of the both. Three methodshave their advantages and disadvantages, in the design process, can reasonable selectionaccording to the concrete circumstance. The industrial test results showed that the desulfurizationrate of this process is up to82%. At the same time, this process has the advantages of lowequipment investment, small occupied area and low operating cost.