A $19 million expansion of Cargill Inc.'s grain export terminal at Norfolk was announced yesterday by the giant, Minneapolis-based commodity marketing and processing company.

Already the largest commodity complex on the East Coast, the Norfolk facility will be capable of handling more than 200 million bushels of grain annually when construction is completed late in 1979.

According to Clifford M. Roberts, Cargill vice president for commodity marketing, the company's grain-handling capacity will be boosted more than 40 per cent and storage capacity will be increased from 5.5 million to 7.3 million bushels.

Roberts said that elevators at the port of Norfolk now handle some 6 per cent of U.S. annual grain and oilsee exports. Most of the 138 million bushels of soybeans, corn, wheat and barley handled at the Norfolk terminal last year was produced within 250 miles with the balance shipped in from the Midwest.

Cargill cited a growing world demand for U.S. crops as the main reason for its expansion. The company is one of a handful of large international grain traders and is privately owned.

New rail yard and equipment and a hydraulic truck-unloading system will be installed as part of the expansion to permit more rapid loading of ships at the facility, opened by Cargill in 1957.