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Bureau of Mines / Minerals yearbook: Metals, minerals, and fuels 1972
Year 1972, Volume 1 (1972)

Morning, John L.
Chromium,   pp. 289-299 ff. PDF (1.1 MB)


Page 298

298 MINERALS YEARBOOK, 1972 
TECHNOLOGY 
 Processes for the production of stainless steel continue to be developed
and improved. Most of the processes utilize lower cost high-carbon ferrochromium
rather than higher cost low-carbon ferrochromium. 
 Joslyn Stainless Steel, a division of Joslyn Manufacturing and Supply Co.
and a pioneer in the development of the argonoxygen decarburization (AOD)
process, believes that it has perfected a process for substituting nitrogen
for a significant part of the argon used in the process. Spartan Steel and
Alloy Ltd. (United Kingdom) also found that nitrogen can partially replace
the more expensive argon. 
 Allegheny Ludlum, Inc., teamed up a basic oxygen furnace (BOF) with a hot
blast cupola furnace at its Natrona, Pa., plant.6 Stainless steel scrap,
high-carbon ferrochromium, and molybdenum oxide are cold charged to the BOF
furnace to which the cupola hot metal is added. optimum charge rate has been
66.5% hot metaL Chromium recovery rates range from 88.7 to 92.5%. 
 For the production of most nickel stainless steel grades, Allegheny utilizes
a vacuuni refining process (AVR) which employs an electric furnace for melting
and a vacuum refining unit. Decarburizing is achieved by injecting oxygen
below the liquid metal surface while it is held at reduced pressure. Chromium
yield in the AVR unit was reported at 98.1% and overall chromium recovery
at 92.6%.7 
 Sweden's Uddeholm Steel Corp. developed a stainless steel process similar
to the AOD process, but in place of argon to carry off the carbon monoxide,
water vapor is injected through the furnace bottom. Reduced refractory wear
is claimed; however, the process is limited to stainless grades containing
less than 0.15% carbon. The firm reports a savings of $8 per ton in the manufacturing
of stainless steel. 
 Outokumpu Oy (Finland) continued to develop a process for the production
of electrolytic chromium. Chromium metal containing 200 to 300 ppm oxygen,
20 to 40 ppm nitrogen, and 10 ppm sulfur was purified in bulk to less than
1 ppm oxygen, 5 ppm nitrogen, and less than 5 ppm sulfur. The material was
then processed into 
a wrought bar by direct extrusion in an evacuated sheath.8 Small quantities
of interstitial elements in chromium metal in the past has prevented processing
commercial chromium metal to ductile metal. 
 An improved electrorefining process was developed for the preparation of
high-purity chromium with low-interstitial content. High-purity commercial
chromium metal was electrorefined in a chromic chloride (CrCl2) electrolyte
at cathode current densities of 40 to 210 amperes per square foot. Average
current efficiency and chromium recovery were 96% and 99%, respectively.'
 Two new chromium plating processes were developed that could substantially
reduce repair and salvage costs. The first was an electrolytic process that
can be taken to the automobile bumper. The second was a hard chromium plating
system primarily intended for use in moldmaking and tool and die operations
for salvaging worn or mismatched parts. 
 The Central Research Institute (India) reported the development of a self-regulating,
high-speed chromium salt. The performance characteristics of the formulation
demonstrate the following advantages over conventional plating: Higher production
rate; formation of smoother, brighter, and harder deposits; less frequent
need for accessories such as jigs; and elimination of control of critical
constituents such as sulfate.10 
 Bureau of Mines researchers determined low-temperature heat capacities and
hightemperature enthalpies calorimetrically for sodium chromate.l1 
 6 Iron Age. Chromium Recovery Improved in Stainless Refining. V. 209, No.
23, June 8, 1972, pp. 59—60. 
 ° Work cited in footnote 6. 
 8 Sced. I. R. Production of High-Purity 
Wrought Chromium by Hydrogen Reduction and 
Extrusion Without Intermediate Melting. J. Less 
Common Metals, v. 27, No. 3, June 1972, pp. 
261—267. 
 ' Lei, K. P. V.. J. M. Hiegel, and T. A. Sulivan. Electrolytic Preparation
of High-Purity Chromium. J. Less-Common Metals, v. 27, No. 3, June 1972,
pp. 353—365. 
 10 Journal of Mines, Metals and Fuels. Formulation for High-Speed Chromium
Plating. V. 20, No. 4, April 1972, p. 124. 
 11 Fcrrante, M. J., J. M. Stuve, and M. P. Krug. Low-Temperature Heat Capacities
and High-Temperature Enthalpie, of Sodium Chromate. BuMines RI 7691, 1972,
12 pp. 


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