1) Melting process. Molten iron and scrap contain C, Mn, Si, P, S and other impurities, in the process of low temperature melting, C, Si, P, S are oxidized, even if the impurities in the elemental state become the impurities in the chemical state, in order to facilitate the further removal of impurities in the later stage. Oxygen comes from rust (Fe2O3·2H2O) in the charge, iron oxide scale, added iron ore, and oxygen and blown oxygen in the air. The oxidation process of various impurities is carried out between the interface between the slag and the molten steel.

(2) Oxidation process. The oxidation process is a reaction of decarbonization, phosphorus removal, gassing, and impurity removal at high temperatures.

(3) Deoxidation, desulfurization and tapping. At the end of oxidation, the steel contains a large amount of excess oxygen, and the excess oxygen in the molten steel is removed by adding block or powdered ferroalloy or multi-element alloy to the molten steel, and the harmful gas CO produced is discharged with the furnace gas, and the resulting slag can be further desulfurized, that is, in the final tapping process, the slag and steel are strongly mixed and washed to increase the desulfurization reaction.

(4) Refining outside the furnace. The molten steel smelted from the steelmaking furnace contains a small amount of gas and impurities, and the molten steel is generally injected into the refining ladle for argon blowing, degassing, ladle refining and other processes to obtain purer steel.

(5) Casting. Pure molten steel coming out of a steelmaking furnace or refining furnace can be tapped, when its temperature is suitable and the chemical composition is adjusted appropriately. The molten steel is taken out into the ingot mold or continuous steel casting machine through the molten steel ladle to obtain the steel ingot or continuous casting billet.

Pouring is divided into two ways: die casting and continuous casting. Die casting is divided into two types: upper casting method and lower casting method. The upper casting method is to inject molten steel from the ladle directly into the mold through the upper mouth of the casting mold to form a steel ingot. The betting method is to pour the molten steel in the molten steel ladle into the pipe and flow the steel bricks, and the molten steel enters the mandie from the lower mouth of the steel ingot mold. The molten steel solidifies in the mold to obtain the ingot. The ingots are sent to the soaking furnace of the rolling mill for heating through the de-insulation cap, and then the ingot molds are transported back to the steelmaking plant for mold work.

Continuous casting is the pouring of molten steel from the ladle into the tundish and then into the cleaner. After the molten steel passes through quenching, the billet is pulled out of the mold by the blank drawing machine at a certain speed, and after secondary cooling and forced cooling, after all the cooling, it is cut into a continuous casting billet of a certain size, and finally sent to the rolling workshop.

2. The main safety technology of steelmaking production

(1) Prevention of explosion accidents of elbows or reducers. Due to the large flow rate and large local resistance loss, the curve or reducer of the oxygen tube in the upper part of the oxygen lance is easy to induce high-purity, high-pressure and high-speed oxygen explosion if there is slag in the tube or the degreasing is not clean. Accidents should be avoided by improving the design, preventing sharp bends, slowing down the flow rate, blowing pipes regularly, cleaning the filter, and improving degreasing.

(2) Prevention and control of flashback and explosion accidents. The negative pressure of the oxygen pipe and the blockage of the nozzle of the oxygen gun caused by the use of oxygen at low pressure are easy to be tempered by the gas poured tank generated by the high-temperature molten pool, and an explosion accident occurs. Therefore, oxygen pressure should be closely monitored. When multiple furnaces use oxygen, do not rush to use oxygen, so as not to cause pipe backfire.

(3) Prevention of steam resistance explosion accidents. Due to operation error, the return water of the oxygen lance is blocked, and the accumulated water of the oxygen lance is vaporized in the high temperature of the molten pool to prevent the high-pressure water from entering. When the vapor pressure in the oxygen lance is higher than the strength limit of the gun wall, an explosion occurs.

3. Safety technology of scrap steel and furnace dismantling and blasting

(1) Possible hazards of blasting: explosion seismic waves; blast waves; hazards of debris and flying blocks; Noise.

(2) Safety countermeasures: regularly inspect and inspect equipment such as steel furnaces, molten steel tanks, molten iron tanks, and iron mixing furnaces; Improve safety technical regulations and strictly enforce them; do a good job of personal protection; Flanges and valves that are prone to air leakage should be replaced regularly.