Continuing cold temperatures during the past weeks have turned Baltimore's coal-exporting business into an unwieldy nightmare. Seventy-five-ton cargoes of coal are freezing solid inside incoming railroad cars, drastically slowing the process of loading the coal into waiting ships.

The results have been a two-way backup, along the rail system and among the ships in Baltimore harbor, and a loss of as much as $1.7 million for the area's economy over the past few weeks, according to industry officials.

Nearly 8,000 coal-filled freight cars are waiting on the tracks of the Chessie railroad system in the East, and a line of eight empty ships is waiting in Baltimore harbor to take coal to Japan, Belgium and Turkey, according to railroad officials and local shipping agents.

Already, six ships scheduled to load coal at Baltimore this month have been diverted to Hampton Roads in Virginia, where there is no freezing problem.

Another eight, also scheduled to steam into Baltimore this month, will have to wait at least until February before they will be able to load, according to Albert J. Knighton, vice president of John S. Connor, Inc., a firm of Baltimore freight forwarders.

The backup of frozen coal cars is worse in Baltimore than anywhere else along the eastern seaboard, according to railroad officials. However, ports in Pennsylvania and New Jersey are also experiencing backup problems.

"Baltimore is the closest major port to the coal fields" of Ohio, Pennsylvania and West Virginia, said Gary Fulton, a Conrail spokesman. "Baltimore seems to be the major bottleneck on the East Coast . . . They have such a great volume, it doesn't take long to back it up."

Fulton added that "a lot of cars scheduled to go to Baltimore from central Pennsylvania have been diverted to Port Richmond" in Philadelphia.

At Port Reading in northern New Jersey, the frozen coal has slowed loading procedures for the barges that serve the state's largest utility, Public Service Electric and Gas Co., forcing the utility to dip into its reserves slightly.

In Baltimore, the problem was made worse in the last 10 days by the painfully slow loading of the Dover Maru, a ship bound for Japan. Instead of taking only two days to load its cargo of coal, as is normal, the freighter starter loading Dec. 29 and is expected to finish the job today, according to Knighton.

Bernard Dillon, a Chessie system spokesman, said the freight yards are equipped with two thawing sheds that can hold 20 freight cars each, and can thaw their cargoes in about an hour by the use of propane heaters.

The coal shipped to Baltimore and other eastern ports is washed to remove impurities before it is loaded on railroad cars. It is usually dried thereafter, but the coal loaded onto the freight cars may contain as much as 5 per cent moisture, a spokesman for the New Jersey utility said.

In addition, the cars that carry the coal are open to the elements during their trip to the eastern seaboard.

According to a two-year-old University of Maryland study, about $6.50 is added to the state's economy every time a ton of bulk cargo, like coal, passes through the port of Baltimore. The money is made up of taxes, agent's fees, handlers' fees and other revenues.

The six ships that had been diverted by yesterday were scheduled to load 270,000 tons of coal, freight executive Knighton said yesterday.

Chessie spokesman Dillon said that the situation may clear up rapidly once the Dover Maru is loaded and gone.

The new coal on its way to Baltimore appears to be unfrozen, he said --(Wednesday) in Frederick. that coal's for the next boat, and it doesn't look frozen at all. You could pick it up with a shovel."