to protect metal surfaces against sea water corro- 
sion, and as a widely used constituent of alumi- 
num alloys. 
The factors involved in extracting magnesium 
from sea water are somewhat different from those 
of bromine.?* From an oceanographic or climatic 
standpoint, location is not as critical. For example, 
water temperature has little effect on the magne- 
sium recovery process. More important is a loca- 
tion favorable to the supply of raw materials and 
power. The proximity of abundant natural gas, the 
fuel for Dow’s electrical power generation, is 
paramount. The process also requires a cheap 
source of lime. For this, Dow purchases oyster 
shells dredged inexpensively from nearby 
Galveston Bay (Figure 53). Another raw material, 
sulfur, also is produced in south Texas and needs 
to be shipped only a short distance. 
Figure 53. Oyster shells from Galveston Bay 
serve as a cheap source of lime, required in the 
magnesium extraction process. (Dow Chemical 
photo) 
One aspect of extracting magnesium from sea 
water, vis-a-vis extraction from inland brines, is of 
special interest. The lower concentration of mag- 
nesium in sea water requires more water to be 
pumped. However, since the Freeport plant is only 
nine feet above sea level, the water does not need 
24 Shigley, C.M., op. cit., p. 7. 
333-091 O-69—17 
to be pumped as high a vertical distance as Dow’s 
inland wells which are about 5,000 feet deep. 
That lower sea water concentrations represent 
no handicap was demonstrated by comparative 
costs published after World War II. The Velasco, 
Texas, plant built for the Federal Government 
bettered by nearly 30 per cent the lowest cost of 
other Government plants using more concentrated 
magnesium sources from inland brines. 
d. Magnesium Compounds Magnesia (magnesium 
oxide) is the principal product of the magnesium 
compounds industry. It is widely used as a basic 
refractory for metallurgical furnaces. A moderate 
percentage of these compounds is still mined from 
old geological basins in Ohio, Texas, and Michigan, 
with wells being drilled as deep as 5,000 to 6,000 
feet. 
There are at present eight plants in the United 
States producing magnesium oxide and depending 
on the ocean as a source of raw material. One 
plant produces these compounds from sea-salt 
bitterns, although such operations are expected to 
stop soon.?* 
As Figure 52 shows, the United States produces 
78 per cent of the world-wide output of those 
magnesium compounds extracted from the sea 
water. 
e. Bromine Of all the minerals extracted com- 
mercially from sea water, bromine is the least 
concentrated, about 65 parts per million. 
All facilities directly processing sea water use a 
modification of the blowing-out process developed 
originally for use on underground brines.?® In 
1931 the process was modified to use sea water as 
a raw material. The Ethyl-Dow facilities at Free- 
port, Texas, have been operating since 1940. Large 
sea water plants are also in operation in France, 
Sicily, and England. 
There are a few inland brines, as in Arkansas, 
having very high concentrations of bromine ap- 
proaching 5,000 ppm. Bromine also has concentra- 
tions approaching 5,000 ppm in the Dead Sea. 
Inland brines are subject to depletion allowances, 
but this is not true of sea water sources, as they 
are considered unlimited reserves. 
25 Mclihenny, W.F., op. cit., p. 123. A bittern may be 
defined as a bitter solution remaining in saltmaking after 
the salt has crystallized out of sea water or brine. 
26Tbid., p. 124. 
VI-193 
