Method for adding calcium-iron alloy in steelmaking process

Abstract

The invention discloses a method for adding a calcium-iron alloy in a steelmaking process, and belongs to the field of steelmaking. The method comprises the following steps: dividing calcium and iron into multiple batches, covering the lower part of the calcium and iron by using a ferrosilicon pad, covering the upper part of the calcium and iron by using ferrosilicon, and then adding the calcium and iron into an RH vacuum tank together. The calcium yield can be increased, and the Ca content of a finished product is increased.

Description

Technical Field

[0001] The present invention relates to steelmaking, and in particular to a method for adding calcium-iron alloy during the steelmaking process. Background Art

[0002] Zhanjiang Iron and Steel produces a calcium-containing steel with a target calcium content of 15ppm in the finished product, with a lower limit of 10ppm. The process involves the following steps: converter - RH refining - continuous casting. The specific steps of RH refining are: ladle loading - vacuum decarburization - aluminum alloy addition - silicon alloy addition - calcium iron addition - vacuum circulation - and ladle removal. This steel requires the addition of three alloys: calcium iron, aluminum iron, and silicon iron. Calcium iron can only be added during the RH refining process via the RH vacuum tank; it cannot be added at other stages.

[0003] The existing technology uses a vacuum hopper to sequentially add 2000kg of Taiwan aluminum, 4600kg of ferrosilicon, and 450kg of calcium iron. Each of the three alloys is added separately, and 450kg of calcium iron is weighed into the vacuum hopper. The hopper's gate valve is then opened to allow the calcium iron to fall into a vacuum tank and melt into the molten steel, circulating evenly. The problem with this method is that the density of calcium iron is approximately 2kg / cm³, far lower than the density of molten steel (7kg / cm³). As a result, most of the calcium iron floats to the surface of the molten steel and burns, leaving only a very small amount of it to be incorporated. Production practice has shown that this method yields only 3% calcium, and the average calcium content in the finished product is only 10ppm, rarely reaching 15ppm. Summary of the Invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a method for adding calcium iron alloy during steelmaking process; to solve the current problem that the yield of calcium iron alloy added in RH vacuum tank is too low.

[0005] Technical solution: A method for adding calcium iron alloy during steelmaking, comprising: dividing calcium iron into multiple batches, padding the lower part with ferrosilicon, covering the upper part with ferrosilicon, and then adding them together into an RH vacuum tank.

[0006] Beneficial effect: The present invention divides calcium iron into small amounts and multiple batches, pads the lower part with ferrosilicon, covers the upper part with ferrosilicon, and then adds them together in a new way, thereby improving the calcium yield and increasing the Ca content of the finished product. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 Schematic diagram showing the comparison of the calcium and iron addition method before and after optimization of the present invention;

[0008] Figure 2 It is a graph showing the change in calcium yield before and after the implementation of the present invention. DETAILED DESCRIPTION

[0009] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0010] Example

[0011] First, weigh 800kg of ferrosilicon to the bottom of the vacuum silo, then weigh 225kg of ferrocalcium and press it on the ferrosilicon, and then weigh 1500kg of ferrosilicon and press it on the ferrocalcium, forming a "sandwich" alloy structure. Add them all at once. Repeat the above steps to add the second batch of 225kg of ferrocalcium.

[0012] Comparative Example

[0013] Weigh 450kg of calcium iron directly into the vacuum silo and add 450kg of calcium iron separately at one time.

[0014] Comparison of the adding methods of the embodiment and the comparative example Figure 1 shown.

[0015] This operation method began to be promoted and tested in June 2023, and was fully solidified and implemented in July 2023. Before implementation, the average calcium and iron addition in the furnace was 450kg, the calcium recovery rate was 3.2%, the calcium content of the finished product was 11.5ppm, and the proportion of Ca≥10ppm was 64.7%. After implementation, the average calcium and iron addition in the furnace was 450kg, the calcium recovery rate was 4.36%, the calcium content of the finished product was 15.6ppm, and the proportion of Ca≥10ppm was 100%. The changes in calcium recovery before and after implementation are as follows: Figure 2 shown.

[0016] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for adding calcium iron alloy in a steelmaking process, characterized in that: include: The calcium iron is divided into multiple batches, and the lower part is padded with ferrosilicon, the upper part is covered with ferrosilicon, and then added into the RH vacuum tank together.

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