Steel making

Steel making, broadly speaking, is an oxidation process in which impurities such as carbon, silicon, manganese, phosphorus and sulfur present in the pig iron are removed to specified levels. It can be anticipated from the Ellingham diagram that at about 1600 °C, the elements C, Si, and Mn would oxidize preferentially before iron undergoes excessive oxidation. The oxidation reactions may be represented by 

Phosphorus and sulfur are present in pig iron and need to be removed in steel making because these elements, if present in any significant quantities in the steel, result in deterioration of its mechanical properties. The concentration normally tolerated is 0.04% for each of these elements, though in high-quality steels much lower levels are required. 

During steel making, preferential oxidation of phosphorus is possible if 

Considering the phosphorus oxidation reaction given earlier, and applying the Van t Hoff isotherm for nonequilibrium conditions, 

Standard free energy change of this reaction is given by 

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Douglas E. Lowenhaupt, M.S., Group Leader, Coke Laboratory, CONSOL, Inc. Member, American Society for Testing and Materials, Iron and Steel Making Society, International Committee for Coal Petrology (Section 27, Energy Resources, Conversion, and Utilization)... 

The ability to bond natural rubber to itself and to steel makes it ideal for lining tanks. Many of the synthetic elastomers, while more chemically resistant than natural rubber, have veiy poor bonding characteristics and hence are not well suited for hning tanks. 

Figure 1.6 Dark oxide and deposit lobes on a copper continuous caster mold from a steel-making operation. Since heat transfer is high, even small amounts of deposit are unacceptable.

Elimination. Since laminations result from steel-making and steelforming processes, little can be done to eliminate defects once they have survived quality inspections at the mill. If laminations are suspected, ultrasonics or radiography may disclose them. They may also be observed visually at cut ends of plate, pipe, or tubes if the cut intersects the lamination. 

Cost rules out almost all alternative materials for long-distance pipe lines it is much cheaper to build and protect a mild steel pipe than to use stainless steel instead - even though no protection is then needed. The only competing material is a polymer, which is completely immune to wet corrosion of this kind. City gas mains are now being replaced by polymeric ones but for large diameter transmission lines, the mechanical strength of steel makes it the preferred choice. 

Changes in Steel-Making Processes in the United States... 

Steel-making slag Steel making Some returned to blastfurnaces, remainder dumped or used as fill near steel works, or sold As roadstone... 

General 1. Use cokeless iron- and steel-making processes, such as the direct reduction process, to eliminate the need to manufacture coke. 2. Use beneficiation (preferably at the coal mine) and blending processes that improve the quality of coal feed to produce coke of desired quality and reduce emissions of sulfur oxides and other pollutants. 

De Beer, J. Worrell, E. and Blok, K. (1998). Future Technologies for Energy Efficient Iron and Steel Making. Annual Review of Energy 3nd the Environment 23 123-205. 

Where considerable quantities of energy are used in the process, relatively cheap and abundant sources of energy need to be available (for example, alumina and aluminum smelting, steel making). 

In the last decade there has been increased interest in the ferritic steels stimulated originally by the availability of new steel-making processes which gave hope that the brittleness problem could be solved by suitable control of carbon and nitrogen contents. This hope has only been partially realised, but as a result a number of new grades have been marketed which do represent useful additions to the range. These have became known collectively as Super Ferrities . Some examples are in Table 3.12. A substantial amount of relevant information was presented at the conference indicated in Reference 5. 

In this connection it must be pointed out that standard samples which have been analysed by a number of skilled analysts are commercially available. These include certain primary standards (sodium oxalate, potassium hydrogenphthalate, arsenic(III) oxide, and benzoic acid) and ores, ceramic materials, irons, steels, steel-making alloys, and non-ferrous alloys. 

Steelworks Waste Heat Boilers Steelworks waste heat boilers bum the various by-product gases from coke ovens and by-product works in an integrated steel-making facility. The gases burned are ... 

Basic Oxygen Furnace Boilers (BOF Boilers) Basic oxygen furnace boilers are commonly employed in the BOF steel-making process. A WH boiler is fitted into the flue gas hood. The WH boiler may be either a steam generator of water-wall membrane construction or a steam-pressurized HTHW boiler. Where a steam generator is employed, the steam is fed to the plant for general use. 

Chloride Chloride ions are strongly adsorbed by steel, making it difficult to passivate. High chlorides in steam-water circuits increases the risk of stress corrosion cracking of austenitic steels (type 300 stainless steels) and increase the rate of pitting corrosion under sludges and deposits. 

C20-0066. Determine A G ° for each oxidation reaction that occurs in a steel-making converter. Compare your values with A G ° for the reaction of iron with O2 to give F 2 O3. ... 

Steel-making slag Steel making Some returned to blast- As roadstone... 

Richardson, F.D. and Jeffes, J.H.E. (1952) The thermodynamics of substances of interest in iron and steel making. III. Sulfides Iron Steal Inst. J., 171, 165-175. 

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