Steel production oxygen used

Many metals are fairly easily oxidized. The atmosphere contains a powerful oxidizing agent oxygen. Because metals are constantly in contact with oxygen, they are vulnerable to corrosion. In fact, the term corrosion is sometimes defined as the oxidation of metals exposed to the environment. In North America, about 20% to 25% of iron and steel production is used to replace objects that have been damaged or destroyed by corrosion. However, not all corrosion is harmful. For example, the green layer formed by the corrosion of a copper roof is considered attractive by many people. 

The 17% ferritic steels are easier to fabricate than the martensitic grades. They are used extensively in equipment for nitric acid production. The oxygen- and sulfur-resistant 30% chromium steel can be used at temperatures up to 1150°C but only for lightly loaded and well-supported furnace items because of its poor creep and brittlement properties when equipment is down to ambient temperatures [18]. 

This group of materials encompasses some of the most widely used construction materials as it includes steels and stainless steels. In pharmaceutical process applications, low-alloy steels are typically limited to structural uses and see little contact with product. Mild steels have been utilized successfully in stills, provided the oxygen content is maintained at very low levels. Tool and die steels may be used in areas where the product is dry and no corrosion is anticipated. 

Metal production accounts for the greatest percentage of oxygen use. For example, oxygen is used to burn off carbon and other impurities that are in iron to make steel. A small amount of these impurities may be desirable in steel, but too much makes it britde and unusable. The... 

Use Blast furnaces copper smelting steel production (basic oxygen converter process) manufacture of synthesis gas for production of ammonia, methyl alcohol, acetylene, etc. oxidizer for liquid rocket propellants resuscitation, heart stimulant decompression chambers spacecraft chemical intermediate to replace air in oxidation of municipal and industrial organic wastes to counteract effect of eutrophication in lakes and reservoirs coal gasification. 

The most common and economically destructive form of corrosion is the rusting of iron. About 25% of the steel produced in the United States is made just to replace steel already in use that has corroded. Contrary to the simplified equation shown earlier in the text, rust is not a direct product of the reaction between iron and oxygen but arises through a complex electrochemical process. Let s look at the facts of iron corrosion and then use the features of a voltaic cell to explain them ... 

A practical example of almost uniform surface corrosion is as follows A pipe made of unalloyed steel St 35 used at approximately 90°C for the transport of service water showed material erosion of the inner surface after 3 years in operation. A layer of corrosion product (mainly iron oxide) had formed on the inside with a practically constant thickness over the entire area. Given the operating conditions, the material corrosion had to be due to oxygen corrosion. 

The foamy slag practice, currently in use in the steel production industry, consists in simultaneously injecting oxygen and carbon (in the form of coal dust) into the slag at the end of the melting. TTie foam of slag is produced by the action of CO bubbles. The CO gas comes from the oxidation of carbon in the metal by the injected oxygen and also from the reduction of the iron oxides (FeO) by the injected carbon. 

Iron can be converted into steel by the Bessemer, Siemens electric arc or basic oxygen processes. The Bessemer process was the first to be patented, but the electric arc (see below) and basic oxygen processes are used in modern steel production. In the basic oxygen process, O2 oxidizes the carbon in pig iron, reducing its content to the levels required for commercial steel (see main text). 

A similar probe can be used to measure the concentration or thermodynamic activity of oxygen in liquid metals. For example, if the probe is dipped in the melt during steel production, the oxygen activity can be measured directly, which is of appreciable advantage. 

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