Some Fundamental Aspects of the Dry Slag Granulation Process
There is a growing interest in development of a dry slag granulation (DSG) process so as to recover the sensible and latent heats from molten slags and convert iron blast furnace slags into a glassy phase that is a suitable replacement for Portland cement. The combination of waste heat recovery and conversion of slag into a saleable product could result in significant reductions in waste and emissions associated with production of steel and cement. The present paper covers some of the fundamental aspects of the reactions taking place during dry granulation of molten slag. In particular, the cut in sulphur emission from slag during DSG as compared with conventional wet granulation process and the dynamics of slag droplet collision with solid surfaces will be covered. Published studies on the thermodynamics of sulphur in slags and the kinetics of sulphur transfer between blast furnace slags and oxidising gas mixtures have been reviewed to ascertain the effects of oxygen partial pressure on sulphur solubility in slags as well as the rate of desulphurisation by water vapor and oxygen containing gas mixtures at temperatures close to 1500 °C. Findings from these experimental studies show that the rate of removal of sulphur from slags could be considerably reduced by formation of sulphate or pyrosulphate species both within the slag as well as on the surface of the molten slag, and the desulphurisation of slags is considerably faster in Ar-H2O than in Ar-O2 with a high concentration of O2. New measurements have been made on the dynamics of wetting and the spreading of molten blast furnace slag droplets as they contact cold metal plates inclined at different angles. The observed behaviour follows a sequence of events (collision, spreading, recoiling, bouncing and/or rolling) which take place in tens of milli-seconds. The duration of the contact and the maximum spreading length were found to be strongly dependent on the initial size of the slag droplet and roughness of the steel surface. The maximum spreading lengths of the droplets were about three times the initial diameter of the droplets. The duration of the contact, spreading and recoiling was found to be strongly correlated with the size of the droplet. Over the temperature range of 1420 to 1580 °C, there was no significant effect of temperature on the dynamics of the wetting and spreading. Furthermore, it was found that droplets contacting the surface of an alumina plate exhibited a very different behaviour as compared with those contacting metal surfaces. In the case of alumina substrates the droplets had a larger maximum spreading diameter over a much shorter spreading period. Such wetting characteristics may be due to the slower heat transfer rate between the slag and the alumina substrate.
molten slag dry granulation heat recovery kinetics sulphur transfer dynamic wetting and spreading
Sharif Jahanshahi Yuhua Pan Dongsheng Xie
CSIRO Minerals Down Under National Research Flagship, Clayton, Victoria, 3168, Australia
国际会议
Ninth International Conference on Molten Slags,Fluxes and Salts(第九届国际熔渣、溶剂与熔盐学术会议 MOLTEN12)
北京
英文
1-14
2012-05-27（万方平台首次上网日期，不代表论文的发表时间）