PATTERNS OF MASS TRANSFER BETWEEN THE LADLE BATH AND SURFACE SLAG

Abstract

The influence specific reagent consumption and the degree assimilation of sulfur desulphurizers on the loss pig iron with coils in the cover slag, which is leaking from the surface melt after completion bucket refining pig iron, is investigated. According to the results analysis industrial data in the conditions bucket pig iron desulphurisation at PJSC «Dneprovsky Metallurgical Plant» it was established that the iron content in the slags, which are rolled after treatment, fluctuates in the range of 60-78%. It is determined that, regardless of the place sampling slag in the height its layer, in the latter is not less than 25% cast iron corks different fractions. The regularities mass exchange between slag and metal bath are determined in conditions change thickness of cover slag and its physical and chemical properties. The classification mechanisms for attracting droplets metal to the amount slag, including by passing the slag - metal into the surface section, with the removal waste gas – metal flow and the draining slag part to the metal bath by circulation flows is proposed.The method determining the size slag – metal gas bubbles floating on the boundary is proposed. The gas bubbles flowing to the upper horizons bath, on the surface which undergoes a reaction formation refractory magnesium sulfide, are surrounded by a film of a metallic melt. The collapse gas bubbles, surrounded by a metallic film, leads to the formation droplets of iron, which are driven by the flow metal into a layer slag. The peculiarities formation and maintenance cast iron cores with surface slag are investigated. It is shown that the droplets cast in the slag in turn coalesce and, provided that they reach a critical size (3-5 mm), when the force gravity becomes more than the force surface tension, settle down into the lower layers slag to the metal boundary, and under conditions sufficient exposure – return to the metal bath. In order to study the features tightening the cover slag to the volume a metal bath from the interfacial slag-metal boundary, grappling with metal droplets, the development mass transfer processes, including the use a mixture reagents of a rotary submersible lance, a series low-temperature experiments using a full factor experiment on a model heavy-duty flood bucket. The factors influence include: the speed submersible lance, the height layer of cover slag, the flow gas. The mathematical models are obtained, which are suitable for determining the degree influence investigated factors on the depth dragging slag to a metal bath. The defining factors influence are as follows: at a rotational speed submersible lance from 0 to 90 rpm. – the speed lance and the thickness layer of cover slag; from 90 to 120 rpm. – thickness layer of cover slag; from 120 to 240 rpm. – speed of lance rotation.