Guniting linings of oxygen converters in the course of melting without stopping the blow

Abstract

Problems arising in guniting converter linings in the course of melting without stopping the oxygen blow are considered. Deposition of a mixture based on magnesite is conducted in an oxygen jet. As the powder particles move in the vessel, they are heated due to the heat of the converter and afterbuming of carbon monoxide, which ensures their strong cohesion with the surface of the lining. The velocity mad diameter of the gas-powder jet are calculated as a function of the concentration of the periclase powder, the distance from the tuyere nozzle, and the temperature of the magnesite particles heated in the vessel. An experimental installation is developed and experiments on guniting in the course of melting without interrupting the blow are conducted. It is established that the gunited coating is deposited on the lining only at the end of melting. The endurance of the coating is 1 -4 heats. In guniting, the temperature of the metal increases by 20 -70°C. The experiments showed the possibility in principle of guniting a converter lining in the course of melting without interrupting the blow.The oxygen converter method of steelmaking is widely used in ferrous metallurg2¢ in Russia. Intensification of steel melting in converters creates severe conditions for the operation of refractory linings. The linings fail due to several causes, the most important of which are the high temperature, the corrosive effect of the slag and the gas medium, and the erosion of the lining caused by the moving gaseous, liquid, and solid phases. All these factors lead to the appearance of local worn regions in the converter lining. The endurance of the lining can be increased by increasing the quality of the refractories used and the differentiated lining, improving the firing regime of the lining, optimizing the parameters of steel melting, and repairing the worn regions of the lining by guniting.In the present paper we consider problems arising in guniting the refractory lining of a converter. Guniting can be conducted by three methods, namely, semi-dry, pulp, and jet ones. Depending on the fuel used, jet guniting can be solid, gaseous or liquid. The best coatings are obtained with the use of gaseous, or liquid fuel. In Russia the most popular method is jet guniting with coke breeze as the fuel, which increases the endurance of the linings to 1000-1500 heats on the average with a consumption of the guniting mixture equal St. Petersburg Institute of Refractories, St. Petersburg, Russia to 1 -3 kg per ton of steel. In Western Europe, the U.S., and Japan the semi-dry guniting method is preferred, which has made it possible to increase the endurance of the linings to 2000-3000 heats with a consumption of the guniting mixture equal to 0.5 -1.5 kg per ton of steel.All the methods mentioned for guniting the lining of a converter are legitimate and the choice is determined by the operating parameters of the converter. It should be taken into account that the semi-dry method is the simplest from the standpoint of design and technology, whereas th...