CS273715B1 - Method of pig iron refining in oxygen converter - Google Patents

Abstract

The invention concerns a method of pig iron refining in an oxygen converter with rapid formation of active clinker preventing the occurrence of accretions on the blast nozzle when blasting oxygen in batches and insetting of calcium in batches. In the initial phase of refining oxygen is blasted for a period of 20 to 25 % of the whole period of oxygen blasting from a distance of 250 to 350 cm from the surface of the bath and calcium is added in batches, with gradual reduction of the distance of the nozzle from the surface of the bath, as well as the batches of calcium.

Description

(57) The present invention relates to a process for refining pig iron in an oxygen converter with rapid formation of active slag, preventing deposition at the blowing nozzle, by blowing oxygen in batches and introducing vague in batches. In the initial refining phase, oxygen is blown for 20-25% of the total blowing time at 250-350 cm from the bath surface and the lime is added in portions, gradually decreasing the distance of the nozzle from the bath surface as well as the lime portions.

CS 273715 Bl f - - *

CS 273715 Bl

The invention relates to a method for blowing oxygen and lime in the production of steel in oxygen converters to prevent deposition on oxygen jets.

At present, when blowing oxygen up, undesirable deposits are formed in the lower part of the nozzle. These deposits are removed either by tanning them or by replacing the nozzle prematurely. Even when cleaning the nozzle by sunbathing, it often causes external damage. In addition to the cost of cleaning the nozzle by tanning, the replacement of the nozzle is associated with a considerable loss of Sase, which leads to a reduction in the converter's power and cooling, resulting in increased pig iron consumption at the next melting.

The described problem is solved by a method of refining pig iron in an oxygen converter with rapid formation of active slag, preventing deposition on the blowing nozzle, by blowing oxygen in batches and charging lime in batches, according to the invention. The principle of the invention is that in the initial refining phase, oxygen is blown for 20-25% of the total blowing time from 250 to 350 cm from the bath surface and the lime is added in portions, gradually reducing the distance of the nozzle from the bath surface. as well as doses of lime.

The oxygen blowing mode is conducted so that in the initial phase of the refining process the PeO content in the slag is min. 18%. The increased content of PeO0 in the initial slag accelerates the formation of active slag, allowing the formation of a slag emulsion preventing metal from adhering to the nozzle. The required increased PeO content in the slag can be achieved, in particular, by extending the initial phase of oxygen blowing at the maximum distance of the nozzle from the bath. For the same purpose, it is also possible to use the rest of the slag from the previous smelting, or the addition of iron ore or scale at the beginning of the refining process. In order to produce active slag it is necessary to add lime in smaller doses, especially in the initial phase of the refining process. Optimum ratios occur when the basic lime charge is added to the converter soil prior to charging the steel scrap and the remainder thereafter during oxygen blowing, in at least two doses.

Example 1

For a batch weight of 180 t and a number of melts of 300 on the lining, the following procedure is desirable:

Distance of the nozzle from the surface in cm Amount of fluffy Og in Nm 300 2 400 200 3 000 180 4 000 200 up to 1,000 before the end of HP 180 to the end of HP

Note: HP - main oxygen blowing.

The lime planting mode is carried out as follows: 6 t of lime per soil, after inhalation

Claims (2)

A second dose of 3 t is added at 1100 Nm 2 Og, and after inhalation of 2 800 Nm 2 Og, the remainder is added. The third dose must be added before lowering the nozzle to a distance of 200 µm. Example 2 Even in the same oxygen blowing regime as in Example 1, in the case of bottom ingrowth i} - - r}, 6 tons of lime should be charged for scrap, after the elevation of 1,100 Nn? Og add a second dose in the amount of 3 tons and after overloading 2 800 Nu? Og and e add the residue. CS 273715 Bl Example 3 In the above-mentioned oxygen scavenging regime, in case of dosing, lime after the pouring of pig iron, it is necessary to divide the dosing into three more times: add 5 t while igniting the bath; Og and after overloading 3,500 Nn? Og is added to the residue. In no case can the entire dose be added at the same time during ignition. In all three cases, undesirable deposits did not form on the blower nozzle. If the lining life exceeds 300 melts, it is desirable to extend the initial period of oxygen scavenging at a nozzle distance of 300 cm. The method of oxygen scavenging and lime charging of the oxygen converters according to the invention is suitable in convertor steel plants with oxygen scavenging. SUBJECT OF THE INVENTION 1. A process for refining pig iron in an oxygen converter with rapid active slag formation, preventing deposition of deposits on a blower nozzle, in the process of blasting oxygen in batches and charging lime in batches, characterized in that oxygen is blown in the initial stage of refining for 20-25 % of the total oxygen recovery time from a distance of 250 to 350 cm from the bath surface and lime is added in portions, gradually decreasing the distance of the nozzle from the bath surface as well as the lime portions. 2. The method of claim 1, wherein half of the total amount of lime is bound to the converter soil prior to pouring pig iron, the remaining lime being added in two batches in the initial refining phase.