Research On The Sediment Of Flus Gas In Direct Reduction Treated By Zinc-bearing Metallurgical Dust

A lot of problems in the flue gas treatment system after zinc containing flue gas produced by treatment of metallurgical dust containing zinc by direct reduction method entered in has become the key to control the rotary hearth furnace process production.In view of the blockage,the normal operation of equipment and other problems caused by zinc flue gas in the flue gas treatment system,in this paper,the theoretical analysis and experimental research are used to study the deposition characteristics of zinc containing flue gas.The behavior analysis of zinc and the mechanism of smoke and dust deposition in flue gas produced by the direct reduction process of zinc metallurgical dust found zinc vapor in flue gas mainly occurred oxidation reaction,and the temperature range of the reaction was 700¹200℃;the stronger the oxidation of flue gas atmosphere（CO₂/CO）is,the higher the starting temperature of zinc vapor re-oxidation will be;the deposition of soot in flue gas is influenced by temperature,alkali metal chloride precipitation and temperature gradient.The deposition of soot in the middle and low temperature zone was more obvious than that in the high temperature zone.In this study,the high-temperature tubular furnace was used to mimic the deposition of flus gas sediment produced by reduction of metallurgical dust,then deposition characteristics including quality distribution,morphology and the main components of deposited were analyzed,The effect of temperature,alkali metal and tail gas atmosphere on the characteristics of flus gas sediment was also studied here.The results showed the deposition starting from 950¹000℃,with the maximum amount of deposition at 600⁷50 ℃ and ended under 600 ℃ indicating that temperature has a significant influence on the characteristics of flus gas sediment.In addition,lower temperature caused the decrease of the sediment particle size and the increase of the degree of chaos of deposition.The main phase of the enrichment region of dust disposition was composed of ZnO,NaCl,KCl and Zn₅（OH）₈Cl₂H₂O.in which the zinc content is 58.50-65.23%.The change of the states of the alkali metal chloride in enrichment region promoted accumulation and reunion of dust particles.Due to the weak oxidizing flue gas,a large number of metallic zinc appeared in the bag dust.After adding a certain amount of alkali metal chloride in the metallurgical dust containing zinc,the pellets were prepared to carry on the direct reduction and the zinc-containing flue gas deposition test to investigate the effect of alkali metal chloride on the quality distribution and concentration of the deposited soot.The results showed that when the amount of alkali metal chloride in the flue gas was increased,there was no significant change in the distribution of the temperature distribution and the location of the temperature distribution of the soot mass distribution and concentration zone,while the amount of soot deposited in the enrichment zone（600⁷50℃）was obviously influenced by the concentration of soot;With the increase of alkali metal chloride in the flue gas,the amount of soot deposited in the enriched area increased,the content of alkali metal chloride increased,while the zinc content decreased slightly.