SULFUR AND PYRITES 1361

Byproduct sulfuric acid 1 (expressed as 600 B.) produced at copper and zinc
plants
in the United States, 1937—41, in short tons

1937
1938
1939
1940
1941
Copper plants' 291,638Zinc plants 542,358
 833,994

220,297
466,879
249,569
528,872
254~ 025
586,912
245,812
672,177


687,176
778,441
840,937
915,989
 ' Includes a small amount of sulfuric acid produced as a byproduct in the
roasting of high-su]ftde gold and silver concentrates.


 Byproduct sulfur is also recovered from coke-oven gas, water gas, refinery-still
gas, natural gas, and other fuel gases. A pictorial flow sheet of the recovery
of sulfuric acid from waste oil-refinery sludges was published in 1941.~
For a long time, hydrogen suffide has been removed from manufactured gases
by passing the gas through trays of iron hydroxide to form iron suffid~,
known as spent oxide. This material has been used as a source of sulfur in
Europe but not to any appreciable extent in the United ' -States. During
the last decade, however, the recovery of sulfur from fuel gases has been
expanding in this country as a result of developments in various liquid-purification
processes. Not all such processes are designed to permit recovery of sulfur
as a byproduct, but those that do may be divided into two classes—those
that recover elemental sulfur and those that give hydrogen sulfide as an
end product. The latter have received increasing attention in recent years.
Typically, -processes that recover elemental sulfur operate on manufactured
fuel gases, whereas those that recover hydrogen suffide are applied to refinery-still
gas and natural gas, and usually these gases are under high pressure. Investigation
has indicated, however, that the phenolate processes, at least, are adapted
to the removal and recovery of sulfur from low-pressure, low-sulfur gases,
such as coke-oven gas.
 Most of the elemental sulfur recovered from gas purification results from
operations using the Thylox process; relatively minor quantities are recovered
from the Ferrox and Nickel processes. Production in 1941 (reduced to 100
percent sulfur) totaled 5,493 long tons; 4,866 tons valued at $136,000 were
shipped. Output came from Illinois, Maryland, Massachusetts, Missouri, New
Jersey, New York, Washington, West Virginia, and Wisconsin; Massachusetts
and New York were the largest producers. The sulfur is produced and marketed
either as a paste containing 37 to 50 percent sulfur or as a dried, relatively
pure sulfur. The fine particle size of thi~ sulfur makes it valuable as a
fungicide and insecticide for agricultural purposes. Of the 1941 shipments
(reduced to 100 percent sulfur), 34 percent was in the form of paste and
the remainder was dried sulfur.
 Most of the hydrogen suffide recovered as a byproduct from fuel gases is
either converted to sulfuric acid or burned as fuel. Recovery is by the phenolate,
phosphate, and Girbotol processes. In 1941 the output of hydrogen suffide
extracted from fuel gases (and, for the most part, converted to sulfuric
acid) was equivalent to 21,197 long tons of sulfur. Most of this was recovered
by petroleum refineries in California -and the remainder by companies in
Illillois, New Jersey, Pennsylvania, and Texas.
 ' Chemical and Metallurgical Englneering,vol. 48, No.5, May 1941, pp. 144-147.
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