Labor Secretary William E. Brock has announced a plan to spend $17.7 million over four years to eliminate "intolerable delays" encountered by coal miners seeking black-lung benefits.

More than 21,000 miners who say their lungs have been damaged by coal dust are awaiting hearings by administrative law judges, and about 5,000 new cases are added each year. At current rates and with the current staff, it would take the department 35 years to catch up, according to a General Accounting Office study that Brock cited.

The United Mine Workers and other unions have criticized the department for inaction, saying workers were frequently incapacitated or died before receiving benefits to help cover their medical care.

The department plans eventually to add 141 claims processors. In the first year, it would add 82 positions at a cost of $4.5 million. Brock said that the Office of Management and Budget has approved the plan, and that he will ask Congress to include it in fiscal 1986 appropriations.

Brock also said the department will continue what he called its "humane and reasonable policy" of not seeking repayment in cases where recipients, through no fault of their own, received black lung benefits they were not entitled to.

THE JOB NOBODY WANTS? . . . One of Brock's toughest tasks in his five months on the job has been finding someone willing to fill the hot seat at the top of the Occupational Safety and Health Administration, formerly held by Robert A. Rowland. Several top candidates, including former OSHA chief Morton Corn, have turned Brock down.

The job is not that attractive, sources said, because of a widely held belief that OMB ties the hands of OSHA officials interested in aggressive enforcement, and because the agency encounters strong criticism from both labor and management who accuse it in turn of nitpicking or caving in to special interests.

"It's becoming sort of a department joke," said a longtime OSHA official. "Here is a major agency and a major job, and everybody knows this was one of his top priorities, and he can't find anyone to take it."

According to OSHA sources, Brock has narrowed his search to three candidates -- Bruce Swanson, OSHA's regional administrator in San Francisco; William Miller, an occupational health specialist for Goodyear Tire & Rubber Co. in Ohio, and John Pendergrass, who holds a similar post with Minnesota Mining and Manufacturing Co.

But Brock will not disclose his choice until after the White House approves his selection and an FBI background check is conducted, according to department spokesman David Demarest.

RIGHT TO KNOW . . . OSHA, meanwhile, is getting ready to enforce a new standard, long sought by unions, that will require employers to inform workers when they are exposed to toxic chemicals. The "hazard communication standard," taking effect Nov. 25, will require new labeling and detailed record-keeping for companies that handle toxic materials.

Acting OSHA chief Patrick R. Tyson said enforcement of the new rule "relies a great deal on the professional judgment" of compliance officers. They will be briefed on the rule in a 32-page instruction booklet that will also be available to the public.

The United Food and Commercial Workers union, whose 1 million members include 40,000 barbers and beauticians, has petitioned Brock to require that the inspectors visit beauty salons, on grounds that many chemicals used there are carcinogenic and not usually labeled as such.

CONCRETE CONSTRUCTION . . . OSHA is proposing to "simplify and update" its standards for concrete and masonry construction, which employs the equivalent of 375,000 full-time workers. A significant number of workers have died in concrete industry accidents, including 51 at Willow Island, W.Va., in 1978 and 14 at Skyline Towers in Fairfax in 1973, Tyson said.

By OSHA's estimate, the new standard, which involves new methods of shoring up walls and supporting masonry structures, could be expected to prevent 13 fatalities and more than 500 injuries a year, and would cost $16 million a year to implement. OSHA will receive comments on its proposals until Dec. 16.