In order to enhance the dispersion of desulfurizing agents into hot metal, the injection of nitrogen gas has been used together with the revolutional stirring by an impeller of a gate type. At the both ends of the impeller, a nozzle is embedded and used for the injection of nitrogen gas into hot metal toward the direction opposite to the movement of the impeller.Water model experiments show that the gas injected efficiently breaks up a cone shaped agglomerate of desulfurizing agents at the bottom of the rotational vortex formed around the impeller shaft and makes it disperse homogeneously into the bath. This suggests that the chemical efficiency of desulfurization will be improved to a greater extent than that without the gas injection.The plant scale equipment has been constructed to desulfurize 60t of hot metal in a ladle. Under the condition of 77 rpm in revolution rate and 3 Nm3/min of nitrogen gas, sulfur content of 0.05% is reduced to 0.012% after the treatment of 1 1 min with calcium carbide of 3kg (75% in purity) per ton of hot metal.The observed rate of desulfurization is reasonably interpreted in terms of the rate controlled by sulfur transfer in hot metal.

No abstract

Synopsis:The operational data of blast furnace performance for longer periods are analyzed by the following parameters as adiabatic flame temperature, height for heat exchange and height of melting level , as well as indices of the thermal state Rsi and the reduction behavior of ferrous oxide Rs and RM n at the lower part ofbl ast furnace. The results are as follows .(1) The temperature of melts changes with the adiabatic flame temperature and height for heat exchange, and is related to the heat balance.(2) Rsi gives the same expression as that for thermal state representing the extent of coke reserve zone. (3) With lower quality coke,RSi, RS and RMn decrease markedly even in a regular operation; this indicates increasing FeO content in slag at the hearth .(4) The increase of sulfur content in injected oil decreases the S distribution ratio between slag and metal. On the other hand, the increase of sulfur content in coke has no influence on it . These differences are caused by the transfer mechanism to gas phase.

Synopsis:The circulation behaviour of Fe, Mn, Si, Mg, Zn, Na, K, S, and Cl in blast furnace is studied. The compounds of circulating elements and the region of the circulation are quantitatively estimated by thermodynamic calculations using gas compositions measured by the vertical probes at a working blast furnace. The probable vapour pressures of circulating species are quantitatively estimated by the mass spectrometric analysis of Knudsen effusates from pig iron, slag, and coke.

I n order to enhance the dispersion oJ desuljurization agents into hot metal, nitrogen has been injected into hot metal jointly with revolutional stirring by an impeller oJ a gate (ype. At both ends oJ impeller, nozzles are embedded and used Jor the injection oJ nitrogen into hot metal toward the opposite direction oJ the movement qf impeller. /lVater model experiments show that the gas injected I!!Jicien tly breaks up a cone-shaped agglomerate oJ demljurizing agents at the bottom oJ rotational vortexJormed around the impeller shrift and makes it disperse homogeneously into the bath. Th is suggests that the chemical ~fficiency oJ de-sl1ljitrizatioll will rise to a greater extent than that without gas i lYection. A plant scale equipmen t has been constructed to desulji,rize 60 t oJ hot metal in a ladle. H ot metal having the suljur content oJ 0 .05rJ% is reduced to 0.012% by treating it with calcium carbide oJ 3 kg (75% ill puri(y) per tOil oJ hot metal Jor 1/ min ullder the condition of 77 rjlm in revolution rate and 3 Nm 3 /min oJ nitrogen. The observed rate oJ desuljilTizatioll is reasonably inter/lreted in terms oJ the mte con/rolled by sulfur transfer ill hot metal.