I need to ship 18-20,000 tons of material (preferably,loose bulk) from
the East coast to the United Arab Emirates and need to know the
cheapest way to do it?

What type of material?  Generally shipping costs depend on the type of material.

An international freight forwarder is an agent for the exporter in
moving cargo to an overseas destination. These agents are familiar
with the import rules and regulations of foreign countries, the export
regulations of the U.S. government, the methods of shipping, and the
documents related to foreign trade. Export freight forwarders are
licensed by the International Air Transport Association (IATA) to
handle air freight and the Federal Maritime Commission to handle ocean
freight.

Freight forwarders assist exporters in preparing price quotations by
advising on freight costs, port charges, consular fees, costs of
special documentation, insurance costs, and their handling fees. They
recommend the packing methods that will protect the merchandise during
transit or can arrange to have the merchandise packed at the port or
containerized. If the exporter prefers, freight forwarders can reserve
the necessay space on a vessel, aircraft, train, or truck. The cost
for their services is a legitimate export cost that should be included
in the price charged to the customer

See this page for a list of licensed freight forwarders.
http://www2.fmc.gov/oti/lff_listing.asp

See this page to learn gov rules on shipping.
http://www.export.gov/exportbasics/exp_001602.asp

Ocean is generally the least expensive method of transit for this
amount of product/material if it goes all at once.

If you ship small quantities of material as it produced then air may
be a better option.