Control method for smelting high carbon low phosphorus steel by converter

Abstract

The invention provides a high-carbon low-phosphor steel control method for converter smelting. The method is carried out through the steps of burdening, blowing oxygen, slagging and tapping. Burden comprises 4.0 to 4.5 percent of furnace entering hot metal C, 0.60 to 0.90 percent of Si, 0.40 to 0.60 percent of Mn, and less than or equal to 0.060 percent of P. The temperature of the hot metal is between 1,280 and 1,300 DEG C. The adding proportion of the hot metal to high-quality returned waste steel is between 10:1 and 13.5:1 (ton). In a slagging process, a batch of slagging materials is first added; lime, sludge balls, pellets and slag-melting manganese-adjusting material are fed into a furnace for slagging; after a first batch of materials are melted, a second batch is added immediately; and a small quantity and multi-batch of the sludge balls and the slag-melting manganese-adjusting material are added in a later stage. Oxygen blowing adopts constant-pressure variable lance positionand variable flow. In a tapping process, a tapping endpoint is first judged according to slagging, lance positions and oxygen consumption; the furnace is inverted to pour slag; and tapping is performed after sampling and qualified assay. Low-phosphor high-carbon tapping can be achieved only by the control method without purchasing or reforming any equipment. The control method is used in the production and application of large-sized converters.

Description

Technical field: [0001] The invention belongs to the field of converter steelmaking, and in particular relates to a control method for converter smelting high-carbon and low-phosphorus steel. Background technique: [0002] High-carbon steel varieties such as steel strands, steel cords, and high-carbon carbon steels have a large market demand, high added value, and promising market prospects. However, the quality control requirements of the above-mentioned high-carbon varieties are high, and their main quality defects are inclusions, surface scars and broken wires caused by high gas content. [0003] The most economical and effective way to improve the purity of molten steel and reduce inclusions and gas content in molten steel is to increase the carbon content of the converter during tapping, reduce the amount of carbon added in the refining process, and avoid excessive carbon added. Excessive flow of argon gas in the medium will cause the molten steel to absorb gas, result...

AI Technical Summary

Problems solved by technology

In the past, the above-mentioned varieties were mainly smelted by electric furnace. The electric furnace adopts slag flow operation, which has good dephosphorization effect and can accurately control the carbon content of the steel. However, its disadvantages are high gas content and slow smelting speed. With the popularization of refining technology, it is gradually transferring to the converter to smelt high-carbon steel varieties

[0004] At present, the current situation of converter smelting high carbon steel is that low carbon tapping technology is generally adopted, and the carbon content is increased by a large amount of carbon after tapping, because when the carbon content at the end of the converter molten steel is high, the dephosphorization effect is poor, resulting in repeated sampling of the converter , the smelting time is extended, which limits the production rhythm, and the end point control is difficult, and each shift affects 2 to 3 furnaces for tapping; at the same time, in order to ensure that the carbon content of the tapping is high and the amount of decarburization is small, the insufficient heat release of carbon oxidation leads to the tapping temperature at the end point Low, even the temperature cannot be measured when reaching the refining furnace. Most of the refining time is spent on power transmission and temperature rise and composition adjustment, which shortens the floating time of inclusions, affects the refining effect of molten steel, leads to poor quality of molten steel, and causes "overholes" Accidents such as flow reduction, some even failed to blow out the argon gas and were forced to reverse the package, which seriously affected the quality of the billet and the actual product

[0005] At present, in order to achieve high-efficiency production of converters, converter steelmaking is widely promoting molten iron pretreatment technology. This technology requires the purchase of special equipment, and equipment investment costs increase; and in the process of molten iron pretreatment, the loss of heat and steel material consumption is large. , the cost of raw materials and energy increases; the heat loss after molten iron treatment is large, the temperature of molten iron entering the converter is low, the temperature of the molten pool is low in the later stage of blowing, and it is difficult to remove slag, and it is still difficult to achieve the result of low phosphorus and high carbon tapping