TH43189A - Method of producing molten steel in a twin furnace. - Google Patents

Abstract

DC60 (08/06/43) This invention describes a method for the operation of a rotary furnace combined with an electric furnace to produce high-purity iron products with certain amounts of silicon and manganese and low amounts of sulfur and phosphorus. The method includes the production of high-purity iron products and products with certain amounts of carbon from compressed material containing iron oxide and carbon. This includes steps for providing a furnace for directly reducing the compressed material containing iron oxide and carbon, pre-reducing the compressed material containing iron oxide and carbon in a furnace with a rotating furnace skin, and the production of a carbon-containing ferrous intermediate. The electric furnace is used to receive the carbon-containing ferrous intermediate from the pre-reducing step, which is fed directly and continuously into the central interior of the electric furnace. The carbon-containing ferrous intermediate is heated in the electric furnace to high temperatures of approximately 1300 °C to approximately 1700 °C, minimizing the passage of air or other unwanted gases such as oxygen during the melting phase while maintaining the high temperature, and removing the product. Very pure molten iron products are obtained from electric furnaces. This method yields products with high iron content, carbon, silicon, and manganese within a specified percentage range, and low sulfur and phosphorus content. Significant reduction of silicon oxide and manganese oxide is observed in the product. The desired high iron-containing products are produced for use in the steel industry. This invention describes a method for operating a rotary hearth in combination with an electric furnace to produce high-purity iron products with specific amounts of silicon and manganese and low sulfur and phosphorus content. The method includes the production of high-purity iron products and products with specific amounts of carbon from compressed material containing iron oxide and carbon, incorporating steps for direct reduction of the iron oxide and carbon-containing material in a furnace with a rotating furnace skin, and the production of a ferrous intermediary containing carbon. The electric furnace is used to receive the ferrous intermediary containing carbon from the pre-reduction step. This is fed directly and continuously into the central interior of the electric furnace. The carbon-containing iron metal is heated in the electric furnace to high temperatures of approximately 1300°C to 1700°C. This minimizes the passage of unwanted air or gases, such as oxygen, during the melting process while maintaining high temperatures. The highly pure molten iron product is then removed from the electric furnace. This method yields a product with a high iron content, carbon, silicon, and manganese within a specified percentage range, low sulfur and phosphorus content, and significant reduction of silicon oxide and manganese oxide in the product. The desired high-iron product is then manufactured for use in the steel industry.

Claims (20)

1. Method for producing high-purity high-carbon molten iron products from iron-carbon contaminated materials. Such high-purity high-carbon molten iron products contain 1.0% to 5.0% carbon. The method consists of the following steps: a) Forming a compressed material containing iron-carbon, silicon oxide, manganese oxide, and sulfur; b) Loading the carbon-containing and compressed material from the forming step into a rotary furnace; c) Pre-reducing the compressed material in the rotary furnace by heating it to create a pre-reduced high-carbon hot iron compressed material; d) Removing the pre-reduced high-carbon hot iron compressed material from the rotary furnace at a temperature of 700°C to 1100°C; e) Directly loading the pre-reduced high-carbon hot iron compressed material from the rotary furnace into an electric furnace; f) Heating the pre-reduced high-carbon hot iron compressed material and... The process involves: b) Melting in an electric furnace at temperatures of 1300°C to 1700°C to create high-carbon molten iron; c) Preventing oxidation of high-carbon molten iron by minimizing the penetration of oxygen-containing gases during the heating process; h) Adding carbon impurities to the high-carbon molten iron to create high-carbon molten iron; i) Purifying the high-carbon molten iron by reducing silicon oxide to silicon, reducing manganese oxide to manganese, and desulfurizing the high-carbon molten iron to produce high-purity high-carbon molten iron; j) Draining the high-purity high-carbon molten iron from the electric furnace; and k) Maintaining the volume of high-purity high-carbon molten iron at a minimum of 1 to 4 times the amount of high-purity high-carbon molten iron periodically through the furnace. 2. The method of claim 1 in which the pre-reduction step is performed in a rotary kiln with a rotating kiln surface and the compressed material is placed on the rotating kiln surface. 3. The method of claim number 2 also involves uniformly packing multiple layers of compressed material onto the surface of a rotating furnace. 4. The method of claim 1 in which the heating and melting steps are performed with electrodes of pre-treated materials selected from a group consisting of carbon and graphite. 5. The method of claim 1 also involves retaining the foamy residue during the heating and melting process. 6. The methodology of claim 1 also involves maintaining the reducing environment within the electric furnace. 7. The method of claim number 6 also involves the expulsion of inert gas inside the electric furnace. 8. The method of claim number 7, in which the expulsion of inert gas inside the electric furnace is expulsion by nitrogen gas. 9. The method of claim number 1 also involves maintaining the temperature at 1450°C to 1700°C inside the electric furnace. 10. The method of claim number 9 also involves maintaining the temperature at 1450°C to 1550°C inside an electric furnace to achieve optimal reduction of silicon oxide to silicon and manganese oxide to manganese in high-carbon molten iron. 11. The method of claim number 9 also involves maintaining the temperature at 1550°C to 1630°C inside the electric furnace to increase the fluidity of the slag. 12. The methodology of claim 9 also involves maintaining the temperature at 1550°C to 1630°C inside the electric furnace to enhance the removal of sulfur from the high-carbon molten iron. 13. The method of claim 1, in which the compressed material is made with a reducing agent present, is chosen from a group consisting of coal powder, fine coal powder, graphite, ash, coke, petroleum, and other carbon compounds. 14. The method of claim 1, in which ferrous and carbon-containing materials are made from materials selected from a group consisting of ferrous waste materials, steel rolling sludge, rolling flakes, iron dust, iron oxide, carbon compounds, silicon oxide, sand, taconite, manganese oxide compounds, magnesium oxide compounds, aluminum oxide compounds, and binders. 15. Method of Claim 1, in which a high-purity carbon-based molten steel product is produced with a sulfur content ranging from 0.005% to 0.016%. 16. The method of claim 1, in which a highly pure carbon-based molten iron product contains at least 95% reducing iron. 17. The method of claim 1, in which the continuous insertion procedure is performed, also involves adding carbon-containing compounds to the electric furnace. 18. The method of claim 1, in which the continuous feeding procedure is performed, also includes the addition of residue conditioning material into the electric furnace. 19. The method of claim 1 also involves adding carbon-containing compounds to the high-carbon, high-purity molten steel product as it is discharged from the blast furnace. 20. The method of claim number 1 also involves keeping the low-density residue in the electric furnace.