Production of Stainless Steel

Nickel. Around 56,000 t of nickel were recycled from scrap in 1994. This is just over one-third of the consumption of the metal. The only mining and smelter in the United States was idle in 1994, although INMETCO (EUwood City, Peimsylvania) was a primary consumer of recyclable metal in the production of stainless steel. Almost one-half of all nickel went into the production of stainless steels with an additional 29% in superaHoys and... 

High purity 50% ferrosihcon containing <0.1% Al and C is used for production of stainless steel and corded wire for tires, where residual aluminum can cause harm fill alumina-type inclusions. These are also useflil in continuous cast heats, where control of aluminum is necessary. High purity grades of 50 and 75% ferrosihcon containing low levels of aluminum, calcium, and titanium are used for sihcon additions to grain-oriented electrical steels, where low residual aluminum content contributes to the attainment of desired electrical properties, eg, significant reduction of eddy currents. 

Nickel, Ni, is also used in alloys. It is a hard, silver-white metal used mainly for the production of stainless steel and for alloying with copper to produce cupronickels, the alloys used for nickel coins (which are about 25% Ni and 75% Cu). Nickel is also used in nicad batteries and as a catalyst, especially for the addition of hydrogen to organic compounds, as in the hydrogenation of vegetable oils (Section 18.6). 

Spent pickle liquor is considered a hazardous waste (K062) because it contains considerable residual acidity and high concentrations of dissolved iron salts. For example, spent pickle liquor and waste acid from the production of stainless steel is considered hazardous. The hazardous constituents in K062 are lead, nickel, and hexavalent chromium. Waste pickle liquor sludge generated by lime stabilization of spent pickle liquor is not considered hazardous unless it exhibits one or more of the characteristics of hazardous waste. An estimated 6 million tons of spent pickle liquor are generated annually in the U.S.1... 

Chromium (Cr) Chromium is very widely used in modem industrial societies. Chromium has been used in iron, steel, and nonferrous alloys because it enhances hardenability and resistance to corrosion and oxidation. Production of stainless steel and nonferrous alloys with Cr are... 

XRF is widely used in industrial applications where a large number of elements need to be determined quantitatively. It is used for continuous quality control in the steel industry (e.g., the determination of Mn, Cr, Ni, Co, etc., in the production of stainless steels), and also for casting quality of coins in the Royal Mint (where Cu, Ni, and Zn are continuously monitored). Geological applications include whole rock analyses and clay identification. The power industry uses it as pollution control management, measuring sulfur and heavy metal concentrations in fuels (coal, oil) and ash. 

Nickel is used mostly for the production of stainless steel and other nickel alloys with high corrosion and temperature resistance. Nickel alloys and nickel platings are used in vehicles, processing machinery, armaments, tools, electrical equipment, household appliances, and coins. Nickel compounds also are used as catalysts, pigments, and in batteries. 

The corrosion resistance of iron-chromium alloys was known in England and France in the early 1800s, but passivity was not clearly recognized and reasonably understood until 1910 as the result of studies by Borchers and Monnartz in Germany. Commercial stainless steels were introduced shortly thereafter in Germany, France, England, and a bit later in the United Slates. Worldwide production of stainless steels now is measured in terms of millions of ions annually... 

Hepatic Effects. Chromium(VI) has been reported to cause severe liver effects in four of five workers exposed to chromium trioxide in the chrome plating industry. Derangement of the cells in the liver, necrosis, lymphocytic and histiocytic infiltration, and increases in Kupffer cells were reported. Abnormalities in tests for hepatic dysfunction included increases in sulfobromophthalein retention, gamma globulin, icterus, cephalin cholesterol flocculation, and thymol turbidity (Pascale et al. 1952). In a cohort of 4,227 workers involved in production of stainless steel from 1968 to 1984, excess deaths were observed from cirrhosis of the liver compared to expected deaths (0/E=55/31.6) based on national rates and matched for age, sex, and calender time having an SMR of 174 with confidence limits of 131-226 (Moulin et al. 1993). No measurements of exposure were provided. Based on limited information, however, the production of chromium compounds does not appear to be associated with liver effects. As part of a mortality and morbidity study of workers engaged in the manufacture of chromium(VI) compounds (84%) and chromium(III) compounds (16%) derived from chromium(VI) in Japan, 94 workers who had been exposed for 1-28 years were given a complete series of liver function... 

The use of spent nickel catalyst in its posthydrogenation form is limited. The only available example of its use is by the M.A. Hanna Company (Cleveland, Ohio). This company mines and smelts nickel, producing a ferro-nickel product of primary use in the production of stainless steels. To conserve its nickel supplies, Hanna modified its system for feeding the production line to allow mixing of spent nickel catalyst with the nickel containing ores at up to 10% of the total nickel feed (108). 

In areas where steels are in contact with the product or raw materials, stainless steels are often used as the workhorse. The production of stainless steel began in the early 1900s. The original efforts in this area were presumably based on the observation that chromium-plated steels parts were highly corrosion-resistant. The end result was the introduction of the ferritic family of stainless steels. The first documentation of the development of this class of steel began to appear in the 1920s. The first American Society for Testing and Materials (ASTM) Specifications for stainless steels were published in 1935. 

Since then, nickel has become a very valuable metal. The most common use is in the production of stainless steel, a strong material that does not rust easily, ft is used in hundreds of industrial and consumer applications. Nickel is also used in the manufacture of many other alloys. An alloy is made by melting and mixing two or more metals. The mtxmre has properties different ftom those of the individual metals. 

Castim - Casting is the final step. Molten metal is cast into pigs using a twin strand pig caster. The bars of metal formed in the molds are called pigs . Pigs are grouped into lots of approximately 20 tons and are shipped to stainless steel manufacturers to be used as remelt alloy for the production of stainless steels. 

Hexavalent forms of chrominm are the most important for indnstrial apphcations. Chrominm (VI) is associated with an increased risk of lung cancer. It is primarily ntilized by the steel industry for the production of ferrochrome, which is, in tnm, nsed for the production of stainless steel. Unlike trivalent chromium, hexavalent chrominm easily... 

Fluctuation in the cost of raw materials used in the production of stainless steel impacts on the economic viability of the use of stainless steel rebars in concrete decks. The rebar cost also depends on the grade of stainless steel used. 

Reduction of Carbon Content. Carbon content can be reduced in the commercial production of stainless steels, but at extra cost. Alloys of low carbon content (e.g., <0.03% C) are designated by letter L—for example, Types 304L and 316L. These alloys can be welded or otherwise heated in the sensitizing temperature range with much less resultant susceptibility to intergranular corrosion. However, they are not immune. 

The data presented on stainless steel point to corrosion as the limiting factor, and the results indicate that cells in the immediate vicinity of the electrode can tolerate the corrosion products of stainless steel. Now, consider the two filled circle symbols for Robblee 83 data. The red filled symbol represents data where platinum was measured in the capsule and in the first millimeter of brain tissue at charge density injection rates of 100 pC/cm /phase AND this datum point lies to the right of the k = 1.75 line No platinum was detected in the capsule or the brain tissue for charge injection rates of 20 pC/cm /phase, a datum point to the left of the k = 1.75 line. These observations suggest that the corrosion products of platinum may be a causative factor. 

Ferrochromium is an alloy of iron and chromium. More than 80% of all chromite ore is consumed in manufacturing this alloy. It is mainly used as the chromium source for the manufacture of stainless steels and other chromium steels. HC ferrochromium with high carbon content (5-6%) is manufactured in electric furnaces with coke as the reducing agent. The process has a high energy consumption, 4000 kWh per tonne of chromium metal. Plants for ferrochromium production have therefore been located in areas with low energy prices. This was one reason why Sweden, without its own chromium deposits, was a pioneer country in this field and in the production of stainless steels. 

Chromium steel became available in 1870 when Julius Braun established the Chrome Steel Works in Brooklyn for manufacturing structural and tool steels (not stainless). Chromium became of great importance from the metallurgical point of view around 1910, when the alloy ferrochromium was introduced and the production of stainless steels started. 

In 2000 the world production of stainless steels was 20 million tonnes. Of this quantity 73% was austenitic. Stainless steels are important for growing economies. 

Great quantities of argon are used in the production of stainless steels with the AOD (argon-oxygen-decarburization) process, treated in Chapter 8 Iron. 

The spectroscopy data obtained from the studies of anodic dissolution of the above metals were used to identify the corrosion products of stainless steels and the order of their appearance in the melt during the anodic dissolution. A spectroscopic study of the anodic dissolution of AISI 321, AISI 316Ti and AISI316L types steels revealed that the process always led to the formation of chromium CrCl4 complex ions in the melt (Figure 6.5.2). 

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