order of magnitude more difficult than dredging 
shelf depth, on-bottom deposits. Yet this type of 
mining justifies continuing attention. 
Present sub-bottom coal and iron mining opera- 
tions extending out from land under the bottom 
involve only incidental marine problems, seepage 
the main concern. As mining progresses, the 
horizontal distance from the surface entrance 
increases, accompanied by corresponding cost in- 
creases. When the economic limit of such mining is 
reached or as deposits far from shore are dis- 
covered, mining through a sea floor entrance must 
be considered. 
Although openings in the sea floor have been 
made for tunnels and dam foundation caissons, 
water depths at the sites rarely exceed 150 feet. 
Opening the sea floor for a permanent shaft 
serviced from a surface platform or a submerged 
base presents formidable engineering problems and 
costs, especially at depths beyond practical diving 
limitations. Ultimately such objectives may be 
accomplished with sea floor entrance and undersea 
transfer capabilities, much of which may result 
from technology developments funded under mili- 
tary programs. 
The techniques to recover offshore sulfur are 
similar to those for offshore oil production, 
making use of fixed above-surface platforms in 
shallow water. The platform supports drilling rigs, 
power plants, shops, warehouse, heliport and living 
quarters. The power plant heats the sea water used 
to melt the sulfur, supplies the compressed air to 
lift the sulfur to the surface and provides the 
electric power to operate the rigs and other 
equipment. 
Wells are drilled directly from the platform into 
sulfur-bearing formations. Hot water is forced 
through pipes into the formations to melt the 
sulfur, which is then lifted to the surface by 
compressed air. Molten sulfur must be maintained 
at a temperature above 240 degrees Fahrenheit 
during handling operations. 
E. Processing and Transportation 
1. Techniques 
Problems of processing and transportation will 
be different for ores recovered from shallow water 
very near to land compared to ores recovered in 
deeper water remote from land bases. Immediate 
VI-186 
processing or enrichment of the ore generally will 
not be necessary if storage facilities are adequate, 
although desirable if transportation costs are high. 
Transportation from the sea surface to land can be 
by surface vessel or barge, by pumping slurry or 
liquid through a pipeline, or by conveyor belt. 
Floating or underwater storage tanks are possible, 
and transfer to transport ships or tankers can be 
accomplished in the same manner as tankers are 
loaded or discharged today. 
Mining operations conducted completely inde- 
pendent of land (as in the deep sea or remote 
shallow banks) will result in entirely different 
processing and transportation problems. Ore will 
be loaded directly into barges, tankers, or ore 
transports. Immediate initial beneficiation or pro- 
cessing may be necessary at sea to reduce weight 
or bulk although this may require large processing 
equipment on the dredging ship. If all operations 
are conducted from a single vessel, this will further 
reduce the amount of ore collected on each trip. If 
multiple vessel operations are anticipated, one 
collecting and processing vessel could operate 
continuously while transport vessels shuttle to 
port. 
2. Attractiveness of Transportation at Sea 
The relative economy of transporting bulk 
materials at sea is an attractive economic charac- 
teristic of working at sea. High density cargoes can 
be transported in bulk carriers, in large quantities, 
and at low unit costs. Thus, a high-grade deposit in 
a remote location on land could be unprofitable 
because of the costs required to construct roads 
and community facilities for workmen. By con- 
trast, an offshore deposit might be more feasible 
economically. These considerations already have 
influenced sand and gravel operations where trans- 
portation costs are high relative to product value. 
Mobility of recovery platforms at sea is another 
attractive feature. Since dredging equipment is 
limited to a few basic types, many systems may be 
applicable to other operations. This might provide 
an opportunity for flexibility for a company 
mining certain minerals in the northern latitudes in 
the summertime but forced to disband operations 
due to winter weather. The mining ships could 
move to a warmer climate and mine a different 
material. In addition, economic fluctuations in the 
values of minerals being produced could make 
