Testing of magnesia-spinellide refractories for gas-oxygen refining of corrosion-resistant steels

Abstract

A new process for production of corrosion-resistant steels provides for refining of the high-alloy semifinished product produced in electrical furnaces in a converter with bottom blowing. Before pouring into the converter, solid metal additions in a quantity of 10-12% of the weight of the heat are added to the semifinished product.The refining is done by blowing the metal bath with gaseous mixtures with different oxidation potentials, which leads to alternation of oxidation and reduction service conditions of the lining. To correct the slag conditions of the heat, lime and fluorspar are added to the converter bath.The gas--oxygen refining (GOR) process is conducted in a converter with a detachable bottom in the center portion of which are located "tube in tube" telescopic tuyeres for supplying gases to the molten metal.In oxidation periods I and II of the heat the metal bath is blown with oxygen with a protective (natural) gas and with a mixture of oxygen and a neutral gas, respectively, and in period III, the reducing period, with only neutral gas.The converter has the form and dimensions normal for similar 60 ton converters. Its walls are lined with fired periclase--chromite parts and the bottom with unfired periclase--carbon ones.Testing in the converter lining of periclase--chromite parts of sintered periclase powder and chromium ore showed their insufficient wear resistance (not more than 53 heats), which was responsible for the use of PShPKh parts made of expensive and scarce fused materials, periclase--chromite, chrome-alumina spinel, and periclase. Under similar service conditions PShPKh parts provide a converter life of up to 80 heats but their use has a significant influence on the economic indices of the process as the result of their high cost.During service of the lining the slag belt, the life of which limits the length of a campaign, is subjected to especially intense wear.The basic failure factors acting on the lining of a GOR converter are the high temperature of the process (up to 1700-1720~ the alternating oxidation--reduction character of the gaseous atmosphere and the molten slag, the aggressiveness of the slag, the unjustifiably long time of contact of the lining with the slag in period III, and the long interheat downtimes.With positive test results in the lining of a GOR converter of PShPKh parts the question of replacement of them with refracturies equivalent in wear resistance but less expensive made of not so scarce and expensive original materials remains a pressing one.

Fluid Flow, Dissolution, and Mixing Phenomena in a Multibottom Tuyere‐Stirred Gas‐Oxygen Refining Furnace

“…The mixture of oxygen, nitrogen, argon, and natural gas (or other hydrocarbons) with adjustable composition is blown into the furnace through bottom tuyeres. [1,2] Its operations have indicated the advantages in terms of high decarbonization rate, high chromium yield, low argon consumption, and high furnace age, etc. [3][4][5][6] In recent years, physical and mathematical simulations have been widely used to study the fluid flow and transport phenomena in metallurgical reaction vessels, such as converters and ladles.…”

“…The mixture of oxygen, nitrogen, argon, and natural gas (or other hydrocarbons) with adjustable composition is blown into the furnace through bottom tuyeres. [ 1,2 ] Its operations have indicated the advantages in terms of high decarbonization rate, high chromium yield, low argon consumption, and high furnace age, etc. [ 3–6 ]…”