Smelting method for improving phosphorus removal rate of converter

Abstract

The invention discloses a smelting method for improving the phosphorus removal rate of a converter. The method comprises the following steps of: at the later stage when steel splashing slag is emptied in the converter, adding 500 to 800 kilograms of lime, slightly stirring, pre-heating, adding waste steel, and blending molten iron; adding a bath of slag forming material such as lime, lightly burnt magnesium blocks, ores and the like when blowing to 45 to 60 seconds, lifting an oxygen lance by 200 millimeters when blowing for 4.5 minutes, continuously adding 4 to 5 batches of ores, and uniformly controlling the heating speed of a molten pool to increase the FeO content of slag; when blowing to 7 minutes, properly lowering the lance for 50 to 100 millimeters, meanwhile, reducing the oxygen pressure to 0.80MPa, and continuously adding 2 to 3 batches of rest lime; and keeping the position of the final point pressure lance at 1,000 millimeters for 1 minute. By adopting the method, full-process slag smelting can be realized, the slag is not re-dried, a good phosphorus removal effect is obtained, the phosphorus removal rate is improved by 10 percent compared with the conventional smelting process, and the requirement for smelting the molten iron with a high content of phosphorus can be met.

Description

Technical field [0001] The invention relates to the technical field of converter steelmaking, in particular to a smelting method for improving the dephosphorization rate of the converter. Background technique [0002] Dephosphorization is mainly in the early stage of smelting. The thermodynamic conditions of dephosphorization mainly include: higher alkalinity, higher FeO content, relatively low temperature and good fluidity slag. In the traditional smelting method, after the converter is tapped, slag splashing is carried out to protect the furnace. After the slag is drained, the scrap steel and molten iron are added. After the converter is blown and fired, a batch of lime, dolomite, ore, etc. are added. Slag material (the amount added is determined by the molten iron silicon and temperature), to balance the temperature in the furnace and the relatively high alkalinity slag produced in the early stage, and use the favorable conditions of low temperature in the early stage of smelt...

AI Technical Summary

Problems solved by technology

[0005] One is to adopt double slag operation, that is, lift the gun when blowing reaches 3-5 minutes, pour out the slag rich in phosphorus, and then erect the furnace to re-add lime to make slag. The disadvantage of this operation: it needs to increase the slag dumping time , which affects the production rhythm; it is difficult to grasp the timing of lifting the gun, the slag is not melted well when the gun is lifted too early, and the slag has poor fluidity and cannot be poured out. It is easy to cause large spray in the furnace, threatening safe production

[0006] The second is to adopt a double-link process, that is, the molten iron is dephosphorized first. When tapping the steel, the temperature of the semi-steel is required to be controlled below 1380°C, and the carbon content is controlled to be above 2.50%. And slag, add a certain amount of ferrosilicon alloy to increase silicon when tapping, and then pour it into the decarburization furnace for re-slagging and other tasks. This process has a high dephosphorization rate, which can reach more than 95%, but the production organization is more troublesome. Generally, smelting Only used when high value-added ultra-low phosphorus steel

However, there are also shortcomings. Only the end point of smelting is controlled, and the whole process of slag removal cannot be realized. Drying may occur in the middle stage of smelting, the dephosphorization efficiency is limited, and molten iron with high phosphorus content cannot be smelted.

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