US 6,582,491 B2 · Method for producing molten iron in duplex furnaces

Abstract

This invention relates to a method for operation of a moving hearth furnace in conjunction with an electric melter for production of high purity iron product having a range of silicon and manganese, with low sulfur and phosphorus content. The method includes producing high purity iron product and a range of carbon content product from iron oxide and carbon bearing agglomerates, including the steps of providing a furnace for direct reduction of iron oxide and carbon bearing agglomerates, pre-reducing iron and carbon bearing agglomerates in a furnace having a moving hearth surface, producing intermediate carbon-containing metallized iron. An electric melter furnace is utilized for receiving intermediate carbon-containing metallized iron from the pre-reducing step, which is fed directly and continuously into a central interior area of the electric melter, with heating of the carbon-containing metallized iron in the electric melter under elevated temperatures of about 1300° C. to about 1700° C., minimizing the ingress of air or other undesirable gases such as oxygen in the melting step while maintaining elevated temperatures, and removing high purity liquid iron product from the electric melter. The method provides a high iron content product having a specified range of carbon, silicon, and manganese percentages, with low sulfur and phosphorus content. There is significant reduction of silicon oxides, and reduction of manganese oxides in the product. An extremely desirable high iron content product is produced for use by the steelmaking industry.

Claims34

Dependent claims

A method for producing a high-purity carbon-containing liquid iron product from iron and carbon bearing material, where said method is optimal for the reduction silicon oxides, comprising the steps of:

(a) forming agglomerates consisting of iron bearing and carbon containing materials;
(b) pre-reducing said agglomerates, by heating said agglomerates at a temperature of about 700° C. to about 1500° C. and producing carbon-containing metallized iron;
(c) discharging said carbon-containing metallized iron at a temperature of about 700° C. to about 1350° C.;
(d) promptly and continuously introducing said carbon-containing metallized iron into an electric melter;
(e) heating and melting said carbon-containing metallized iron in the electric melter at a temperature of about 1450° C. to about 1550° C.;
(f) minimizing the ingress of undesirable gases in said introducing step;
(g) minimizing the ingress of undesirable gases in said heating step;
and
(h) discharging high purity molten iron product from the electric melter.

6 more elements

A method for producing a high purity high carbon molten iron product from iron and carbon bearing material, where said method is optimal for the reduction of silicon oxides to silicon and manganese oxide to manganese, said high purity high carbon molten iron product containing from about 1.0% to about 5.0% carbon by weight of the weight of the molten iron product, said method comprising the steps of:

(a) forming agglomerates consisting of iron bearing, carbon containing materials, silicon oxide, manganese oxide and sulfur;
(b) charging the agglomerates from said forming step into a rotary hearth furnace;
(c) pre-reducing the agglomerates in the rotary hearth furnace by heating the agglomerates to form pre-reduced high carbon hot metallized iron agglomerates;
(d) discharging the pre-reduced high carbon hot metallized iron agglomerates from the rotary hearth furnace at a temperature of about 700° C. to about 1100° C.;
(e) introducing continuously, with minimization of the ingress of oxygen containing gas, the pre-reduced high carbon hot metallized iron agglomerates directly from the rotary hearth furnace into an electric melter;
(f) heating and melting the pre-reduced high carbon hot metallized iron agglomerates, with minimization of the ingress of oxygen containing gas, in the electric melter at a temperature of about 1300° C. to about 1700° C. to form high carbon molten iron, where a temperature of about 1450° C. to about 1550° C. is maintained within the electric melter:
(g) carburizing the high carbon molten iron to form high carbon molten metallized iron;
(h) purifying the high carbon molten metallized iron by reducing silicon oxides to silicon, reducing manganese oxide to manganese and desulfurizing the high carbon molten metallized iron to produce high purity high carbon molten iron product;
(i) discharging high purity high carbon molten iron product from the electric melter by intermittently tapping the melter;
and
(j) maintaining a minimum high purity high carbon liquid iron heel of about 1 to about 4 times the quantity of the intermittently tapped high purity high carbon molten iron product.

8 more elements

Dependencies are inferred from the claim text.

Method for producing molten iron in duplex furnaces

Life of this patent

Method for producing molten iron in duplex furnaces

Life of this patent

Abstract

Claims34