A slag discharge door device for an electric furnace is provided. The device prevents slag from flowing out via a slag discharge port by making a discharge control door body move up and down to and from the upper surface of a supporting body where slag is discharged by flowing to the upper surface, and the discharge of slag is controlled, such that during steel-making work in the electric furnace, the outflow of slag is prevented and heat losses are reduced, the efficiency of arc heat due to the formation of foamed slag is increased, and valuable metals are recovered from the molten slag thereby increasing the percentage of molten steel recovered.

A converter slagging monitoring method and device. The method comprises: acquiring converter smelting data containing converter noise data and oxygen lance vibration data in real time; based on a pre-established slagging monitoring model, calculating the thickness of slags in a converter molten bath by virtue of the acquired converter smelting data; comparing the calculated thickness of slags with a splashing threshold value and a drying threshold value which are contained in the slagging monitoring model, judging whether a comparison result characterizes the occurrence of splashing or drying, and when the comparison result characterizes the occurrence of splashing or drying, acquiring corresponding splashing information or drying information; and finally, according to the splashing information or drying information, making a corresponding splashing control scheme or drying control scheme to guide a subsequent slagging operation so as to achieve the smooth control of the lance position.

A process for producing clean steel products with low nitrogen content, below 35 ppm, in a steelmaking plant comprising a direct reduced iron (DRI) source, which may be a direct reduction plant or a DRI storage facility, an electric arc furnace (EAF), a vacuum degassing system (DS), and a continuous casting system (CC) is disclosed. The process comprises a first stage of melting and refining a metallic iron charge, a second stage of tapping molten steel from the electric arc furnace (EAF) into a ladle, a third stage of exposing molten steel to a pressure below the atmospheric pressure and a fourth stage of casting molten steel to clean steel products. Optionally, the molten steel tapped from the EAF is treated in a ladle furnace (LF) prior to being treated in the degassing system (DS). The metallic iron charge fed to the EAF comprises more than 70% by weight of DRI in the form of pellets or briquettes having a carbon content above 2.5 weight %. Preferably, the metallic iron charge is fed to the EAF at a temperature of 400 C. or higher. The low nitrogen level in the steel products made according to the Application is achieved by forming a first foamy slag in said first process stage and is maintained in a foamy state by controlling the feed of fluxes, oxygen, and carbonaceous materials to the EAF and by forming a second slag, after molten steel is tapped from the EAF, having a predetermined composition capable of continuing the desulfurization and providing a thermal and chemical insulation to prevent nitrogen pickup and promote nitrogen removal of molten steel. The process also comprises carrying out one or more of the following actions: (a) controlling the concentration of nitrogen and sulfur in the raw materials at each process stage, (b) promoting nitrogen removal from steel, (c) decreasing the time spent by the molten steel at each process stage and between each and subsequent process stages, and (d) preventing nitrogen pickup by the molten steel all along said process stages. Steel products made according to the Application comprise the following elements expressed in weight %: C0.05%, Si4.5%, Al2.0%; Mn2.0%; P0.20%; Ni0.200%, Cu0.200%; N0.0030%, Ni0.200%, S0.0035%.

A slag foaming system for an electric arc furnace utilizing algae is described. The algae may be dried algae in particle form that is injected into the electric arc furnace through a solids injector and may be directed into the slag. Other slag foaming compositions may also be injected into a furnace as a function of furnace parameters to create slag foam while maintaining a high yield of slag without excess iron oxide and reduced carbon and carbon dioxide emission. The algae and slag foaming composition may be used in combination for slag formation and control.