St. Lawrence Cement Group Inc posted a bigger first-quarter loss on Tuesday, as lower cement prices and higher operating expenses offset an increase in sales.  The Montreal-based company said it lost C$19.3 million ($14 million), or 47 Canadian cents per share in the quarter ended March 31, down from a year-earlier loss of C$13.7 million, or 33 Canadian cents per share.  Sales rose to C$141.4 million in the quarter from sales of C$126.9 million in the same period a year earlier.  St. Lawrence gave no word on when it will replace its cement plant in Greenport, New York, saying it had received a request for additional information on the project from New York’s Department of State.  With good backlogs and assuming a stable Canadian dollar, the company said it expects to increase sales and margins in 2004.