CHROMIUM 25 
 
sodium chromate. Domestic chromites from Alaska, California, and Oregon were
successfully treated by this procedure. The Bureau devised a column flotation
technique and compared it with conventional flotation of Montana chromite.16
Column flotation produced higher concentrate grades and recoveries than conventional
chromite flotation for both deslimed and undeslimed chromite ore. The Bureau
upgraded high-iron domestic chromite concentrates by a carbonyl process.'7
The highiron chromites were reduced to convert iron oxides to the metal,
then were treated with carbon monoxide to convert part of the iron to iron
pentacarbonyl. The iron pentacarbonyl was then extracted from the concentrate.
Chromic oxide content was improved, by as much as 10% and chromiumto-iron
ratio increased by up to threefold compared with that of the starting concentrates.
The Bureau researched environmental issues associated with chromite extraction
from the Stillwater Complex, MT.18 Specific land, water, air, and other environmental
factors were identified and analyzed as to how they would relate to mining
of chromite deposits. Shrinkage stoping mining methods and gravity concentration
milling were assumed as part of the environmental issues study. With the
exception of technology for ferrochromium smelter sludge reclamation, all
technology necessary for development was found to be available and sound.

The Bureau researched the potential for reducing the chromium content of
stainless and alloy steels to improve chromium use technology. Chromium-nickel
stainless steels with molybdenum, copper, and vanadium for corrosion-resistant
applications, and with silicon and aluminum for heatresistant applications,
were studied.'9 For several reduced chromium stainless steels, tensile properties
were evaluated, corrosion rates were measured, welding performance was evaluated,
stress rupture properties were measured, and oxidation tests were performed.
Additions such as molybdenum, silicon, and aluminum were found to be potential
substitutes for about one-half the chromium in stainless steels for many
applications. The Bureau performed oxidation studies, obtained mechanical
properties, determined stress rupture strength data, and investigated melting,
casting, and working characteristics for iron-manganesealuminum alloys as
a potential substitute for stainless steels.2° The alloys studied
did
not exhibit good oxidation resistance during 
mild thermal cycling and were problematic to melt, cast, and cut. The alloys
were easily hot worked and had good mechanical properties unless aged. Iron-chromium-nickelaluminum
alloys were studied as potential substitutes for stainless steels used in
sulfur-containing environments.21 With minor additions of titanium, manganese,
and silicon to improve workability, sullidation resistance was found to exceed
that of stainless steel types 304 ' and 316; oxidation resistance was equivalent
to that of type 310; and mechanical properties approached those of type 310.
The Bureau investigated a cast-on hard-surfacing technique that improves
wear resistance.22 The cast-on surface was found to be a potential substitute
for weld-rod hard facing. 
The Bureau studied in-plant recycling of speciality steelmaking particulate
wastes.2' Particulate waste such as flue dust, mill scale, and grinding swarf
was pelletized and reduced in an electric-arc furnace. Consistent recoveries
of about 90% of the chromium were achieved. The Bureau cosponsored a workshop
on conservation and sübstitution technology for chromium in bearings.2'
Strategies such as substitution of alternate materials, including metals
and nonmetals, and use of extended life bearings, were identified. 
The U.S. Department of Defense developed a microprocessor-controlled chromium
plating process and studied the effect o plating conditions on the structure
of electrodeposited chromium.25 
The National Materials Advisory Board studied the potentialindustrial application
of plasma processing technology.2' The report identified plasma technology
as potentially applicable to ferrochromium production and to the recovery
of chromium from dusts. Current industrial applications af plasma technology
to ferrochromium production, low-grade chromium ore processing, and chromium
recovery from steel miii baghouse dust were identified. 
The National Institute for Metallurgy, Republic of South Africa, developed
an accurate and precise method for the determination of iron and chromium
in chromite.~ 
The economic recovery of chromite from the UG-2 seam of the Bushveld Complex
was studied by the Council for Mineral Technology (Mintek), Republic of South
Africa.2' A beneficiation process to produce chromite concentrate was developed
and tested at pilot plant and production scales. A low-grade chromite concentrate
was