An apparatus to feed and pre-heat a metal charge to a melting furnace of a steelworks comprises a feeding and pre-heating tower separate from the melting furnace provided with at least one compartment to temporarily contain said metal charge, transfer means to transfer said metal charge to said melting furnace and conveying means to convey the fumes exiting from the melting furnace to said compartment. The apparatus also comprises a post-combustion chamber, disposed adjacent to and below said compartment, and connected on one side to said compartment and on another side to said conveying means, the post-combustion chamber being configured to determine the expansion of the fumes introduced by the conveying means and to direct said expanded fumes toward said compartment along a path such as to determine a desired residence time of said fumes suitable to obtain at least the substantial complete combustion of the unburned gases present in said fumes.

An apparatus to feed and pre-heat a metal charge to a melting furnace of a steelworks comprises a feeding and pre-heating tower separate from the melting furnace provided with at least one compartment to temporarily contain said metal charge, transfer means to transfer said metal charge to said melting furnace and conveying means to convey the fumes exiting from the melting furnace to said compartment. The apparatus also comprises a post-combustion chamber, disposed adjacent to and below said compartment, and connected on one side to said compartment and on another side to said conveying means, the post-combustion chamber being configured to determine the expansion of the fumes introduced by the conveying means and to direct said expanded fumes toward said compartment along a path such as to determine a desired residence time of said fumes suitable to obtain at least the substantial complete combustion of the unburned gases present in said fumes.

Some variations provide a carbon-negative carbon product that is characterized by a carbon intensity less than 0 kg CO.sub.2e per metric ton of the carbon-negative carbon product, wherein the carbon-negative carbon product contains at least about 50 wt % carbon. In some embodiments, the carbon intensity is less than 500 kg CO.sub.2e per metric ton of the carbon-negative carbon product. Other variations provide a carbon-negative metal product (e.g., a steel product) that is characterized by a carbon intensity less than 0 kg CO.sub.2e per metric ton of the carbon-negative metal product, wherein the metal product contains from 50 wt % to 100 wt % of one or more metals and optionally one or more alloying elements. In some embodiments, the carbon-negative metal product is characterized by a carbon intensity less than 200 kg CO.sub.2e per metric ton of the carbon-negative metal product. The carbon-negative metal product can contain a wide variety of metals.

Heat exchange tubes of a heat exchanger are formed of an alloy containing Mn (0.2 to 0.3 mass %), Cu (0.1 mass % or less), and Fe (0.2 mass % or less), the balance being Al and unavoidable impurities. A Zn diffused layer is formed in an outer surface layer portion of the peripheral wall of each heat exchange tube. T200, 0.57A1.5, D/T0.55, and 0.0055A/D0.025 are satisfied, where T is the thickness [m] of the peripheral wall of the heat exchange tube, A is the Zn concentration [mass %] at the outermost surface of the outer surface layer portion, and D is the maximum depth [m] of the Zn diffused layer. The spontaneous potential of the Zn diffused layer is lower than that of a portion of the peripheral wall located on the inner side of the Zn diffused layer.

A method for operating a shaft furnace, in particular a blast furnace, is disclosed wherein at least one gas is introduced into the furnace. To achieve an acceleration of the reaction processes in the furnace, shockwaves are introduced into the furnace.

Methods for improving a toughness and a strength of a stainless steel material are described herein. For example, a high strength stainless steel material can comprise at least 11 wt. % Cr, between 0.01 wt. % and 1.0 wt. % Ni, more 0 wt. % Mo, more than 0 wt. % W, more than 0 wt. % Ti, more than 0 wt. % Nb, and more than 0 wt. % V. In some examples, the high strength stainless steel material can be heat treated with at least one quench treatment and at least one tempering heat treatment. In some examples, the high strength stainless steel material can comprise between 0.01 wt. % and 0.5 wt. % Ni, no more than 0.25 wt. % Mo, no more than 0.1 wt. % W, no more than 0.1 wt. % Ti, no more than 0.1 wt. % Nb, and no more than 0.1 wt. % V.

Some variations provide a carbon-negative carbon product that is characterized by a carbon intensity less than 0 kg CO.sub.2e per metric ton of the carbon-negative carbon product, wherein the carbon-negative carbon product contains at least about 50 wt % carbon. In some embodiments, the carbon intensity is less than 500 kg CO.sub.2e per metric ton of the carbon-negative carbon product. Other variations provide a carbon-negative metal product (e.g., a steel product) that is characterized by a carbon intensity less than 0 kg CO.sub.2e per metric ton of the carbon-negative metal product, wherein the metal product contains from 50 wt % to 100 wt % of one or more metals and optionally one or more alloying elements. In some embodiments, the carbon-negative metal product is characterized by a carbon intensity less than 200 kg CO.sub.2e per metric ton of the carbon-negative metal product. The carbon-negative metal product can contain a wide variety of metals.

The invention discloses a method for preparing a stainless steel seamless tube with ultra-high cleanliness for an integrated circuit and an IC industry preparation device, and a stainless steel seamless tube with ultra-high cleanliness. The stainless steel seamless tube which comprises, by mass, C0.010%, P0.020%, S0.010%, Mn0.10%, Si0.30%, Se0.010%, Al0.010%, Cu0.20%, Cr16.50-17.00%, Ni14.50-15.00%, Mo2.20-2.50%, N0.010%, Ni0.010%, Ti0.010% and the balance Fe and impurities is prepared through a: a stainless steel refining process; b: a vacuum induction melting and vacuum consumable remelting process; c: a stainless steel forging process; d: a hot piercing process; e: a cold working process; f: an inner bore electrolytic polishing, pickling and passivation process; and g: a cleaning process. The stainless steel seamless tube with ultra-high cleanliness prepared through these processes meet the requirements for ultra-high cleanliness and high performance of 316L stainless steel tubes for a semiconductor preparation device.