An inoculant for manufacturing cast iron with lamellar, compacted or spheroidal graphite is disclosed. The inoculant has a particulate ferrosilicon alloy 40 and 80% by weight of silicon, 0.5 and 5% by weight of calcium and/or strontium and/or barium, 0 and 10% by weight of rare earths, 0 and 5% by weight of magnesium, less than 5% by weight of aluminium, 0 and 10% by weight of manganese and/or zirconium, and the balance being iron, wherein the inoculant additionally contains 0.1 to 10% by weight of particulate bismuth oxide particles and optionally 0.1 and 10% by weight of one or more particulate metal sulphides and/or one or more particulate iron oxides, where the particulate bismuth oxide is mixed or blended with the ferrosilicon particles, or is simultaneously added to cast iron together with the particulate ferrosilicon particles.

An inoculant for manufacturing cast iron with lamellar, compacted or spheroidal graphite is disclosed. The inoculant has a particulate ferrosilicon alloy 40 and 80% by weight of silicon, 0.5 and 5% by weight of calcium and/or strontium and/or barium, 0 and 10% by weight of rare earths, 0 and 5% by weight of magnesium, less than 5% by weight of aluminium, 0 and 10% by weight of manganese and/or zirconium, and the balance being iron, wherein the inoculant additionally contains 0.1 to 10% by weight of particulate bismuth oxide particles and optionally 0.1 and 10% by weight of one or more particulate metal sulphides and/or one or more particulate iron oxides, where the particulate bismuth oxide is mixed or blended with the ferrosilicon particles, or is simultaneously added to cast iron together with the particulate ferrosilicon particles.

An inoculant for the manufacture of cast iron with lamellar, compacted or spheroidal graphite is disclosed. The inoculant has a particulate ferrosilicon alloy having about 40 to 80 wt % silicon, about 0.1 to 10 wt % calcium, 0 and 10% by weight of rare earths, for example cerium and/or lanthanum, and up to 5 wt % aluminium the balance being iron and incidental impurities in the ordinary amount, wherein the inoculant additionally has 0.1 to 10 wt %, based on the total weight of inoculant, antimony oxide where said antimony oxide is in particulate form and is mixed or blended with the ferrosilicon alloy particles, or is simultaneously added to cast iron together with the particulate ferrosilicon alloy particles.

A hearth for a traveling hearth furnace for the production of pig iron grade nuggets, the hearth having a synthetic graphite material in direct contact with the process charge in producing a plurality of metallic iron nodules and slag. The process charge including iron containing oxide, a predetermined amount of a reductant and flux, which are carried into and through a reducing, melting and coalescing stages on the hearth, wherein resulting metallic iron nodules and slag are in direct contact with the synthetic graphite material and do not adhere to the synthetic graphite material of the hearth. The absence adherence and ease of removal minimizes any impurities in the pig iron grade nuggets and allows the hearth to be used more than one cycle without the need for any replenishment of the contact surface.

A hearth for a traveling hearth furnace for the production of pig iron grade nuggets, the hearth having a synthetic graphite material in direct contact with the process charge in producing a plurality of metallic iron nodules and slag. The process charge including iron containing oxide, a predetermined amount of a reductant and flux, which are carried into and through a reducing, melting and coalescing stages on the hearth, wherein resulting metallic iron nodules and slag are in direct contact with the synthetic graphite material and do not adhere to the synthetic graphite material of the hearth. The absence adherence and ease of removal minimizes any impurities in the pig iron grade nuggets and allows the hearth to be used more than one cycle without the need for any replenishment of the contact surface.

A spheroidal graphite cast iron meeting N.sub.(5-)250, N.sub.(5-20)/N.sub.(5-)0.6, and N.sub.(30-)/N.sub.(5-)0.2, wherein N.sub.(5-) represents the number (/mm.sup.2) of graphite particles having equivalent-circle diameters of 5 m or more, N.sub.(5-20) represents the number (/mm.sup.2) of graphite particles having equivalent-circle diameters of 5 m or more and less than 20 m, and N.sub.(30-) represents the number (/mm.sup.2) of graphite particles having equivalent-circle diameters of 30 m or more, among graphite particles observed in an arbitrary cross section of at least 1 mm.sup.2.

There is provided with spheroidal graphite cast iron having excellent gas defect resistance where gas defects such as pinholes attributable to the free N are small in number and having mechanical characteristics and machinability equal to or greater than the conventional ones. The spheroidal graphite cast iron consists of, in mass ratio, C: 3.3 to 4%; Si: 2 to 3%; P: not more than 0.05%; S: not more than 0.02%; Mn: not more than 0.8%; Cu: not more than 0.8% (0 is not included); Mg: 0.02 to 0.06%; Ti: 0.01 to 0.04%; V: 0.001 to 0.01%; Nb: 0.001 to 0.01%; and N: 0.004 to 0.008%, with the remnant substantially consisting of Fe and an inevitable impurity.

There is provided with spheroidal graphite cast iron having excellent gas defect resistance where gas defects such as pinholes attributable to the free N are small in number and having mechanical characteristics and machinability equal to or greater than the conventional ones. The spheroidal graphite cast iron consists of, in mass ratio, C: 3.3 to 4%; Si: 2 to 3%; P: not more than 0.05%; S: not more than 0.02%; Mn: not more than 0.8%; Cu: not more than 0.8% (0 is not included); Mg: 0.02 to 0.06%; Ti: 0.01 to 0.04%; V: 0.001 to 0.01%; Nb: 0.001 to 0.01%; and N: 0.004 to 0.008%, with the remnant substantially consisting of Fe and an inevitable impurity.

The present invention provides a novel method for supplying a reducing gas to the shaft part of a blast furnace with which a large amount of reducing gas containing hydrogen at a high concentration can be supplied to a deeper position in the blast furnace (location of the blast furnace closer to the center axis in the radial direction) and with which it is possible to reduce the total generated amount of CO.sub.2 of the CO.sub.2 amount that is reduced by conducting hydrogen smelting in the blast furnace and the CO.sub.2 amount that is generated during production of the reducing gas supplied to the blast furnace. The method for supplying a reducing gas to the shaft part of a blast furnace according to the present invention is characterized by reforming coke oven gas by increasing the temperature thereof to 1200 to 1800? C. in a reactor in which an oxygen-containing gas is supplied to preheated coke oven gas to generate reformed gas in which hydrogen gas is enriched; mixing the reformed gas with CO-containing gas in the reactor so that the hydrogen concentration of the reducing gas is adjusted to 15-35 vol % (wet); and supplying the resultant reducing gas to the shaft part of the blast furnace under a condition of a ratio of a flow rate of reducing gas blown into shaft part/flow rate of reducing gas blown into tuyere >0.42.

For the purpose of providing a method of die cast product of spheroidal graphite cast iron and a die cast product of spheroidal graphite cast iron having the number of spherical graphites of 3000/mm.sup.2 or more in an as cast state, there is disclosed a method of die cast product of ultrafine spheroidal graphite cast iron, including the steps of: a melting step of heating and melting raw materials made of cast iron to obtain source melting metal; a spheroidizing treatment step in which a spheroidizing treatment is performed; an inoculation step of inoculating; and a casting step of casting in a die mold. The amount of nitrogen is adjusted so that the amount of nitrogen generated in the time of melting becomes 0.9 ppm (mass) or less.