Negotiators for the coal industry and the United Mine Workers agreed yesterday on a new tentative contract that could end the nation's record 99-day coal strike in 10 days or fewer.

The coal operators made major concessions on points that caused the 160,000 UMW strikers to reject an earlier industry offer. The operators dropped their insistence on wildcat strike controls, and gave new ground on health insurance and pensions for older retirees.

The concessions improve chances of - but not guarantee - rank-and-file ratification and a prompt resumption of full-scale coal production in time to avert energy blackouts and job layoffs in many Midwestern and Eastern states.

The new three-year pact must be approved by the UMW's bargaining council, which was being summoned to Washington for a meeting late today, before it can be submitted to the striking miners for approval.

The process normally takes about 10 days.

Yesterday's agreement does not immediately affect the government's back-to-work order under the Taft-Hartley Act, which miners are widely ignoring anyway.

The agreement came after four days of intensive negotiations prompted by a government-encouraged threat of a break-up in industrywide negotiations and proliferation of company-by-company settlements, which both sides viewed as potentially devastating to their strength and unity.

The new pact retains wage and benefit boosts contained in earlier contract drafts, which the UMW estimated to total nearly 37 percent over three years.

But it differed from them in these key respects:

All reference to disciplinary action against wildcat strike leaders was striken from the contract, leaving the issue to a board of arbitrators, which previously allowed employers to discipline strike instigators and pickets. The rejected contract would have explicitly empowered employers to fire strike leaders, without recourse to arbitration on the severity of the penalty.

Working miners would have to pay up to $200 a year for health care and retirees $150. Under the rejected contract, the maximum deductible was $700. Miners have previously had free "womb-to-tomb" health care although it was subject to cutbacks or cancellation when production royalties declined during strikes or other work stopages. Industry bargainers agreed to guarantee benefit payments in the new contract but insisted on some deductibles to help control costs.

The new proposal would raise pension benefits for most UMW retirees from $225 to $275 a month immediately, instead of spreading the increase over three years. It would, also drop the earlier draft's proposal to increase from 1,000 to 1,450 the number of hours a miner must work to obtain one year's worth of pension credit.

Absenteeism controls that union leaders wanted - but miners indicated they didn't want - were dropped.

One additional vacation day was included, along with elimination of a controversial Christmas shutdown period.

A wage increase of $2.40 an hour over three years, raising miners' average hourly pay from $7.80 to $10.20, would be guaranteed rather than left partially contingent on inflationary pressures. But the principle of cost-of-living increases was retained.

Balanced against these industry concessions, the union had to accept company takeover of the union's trustee-administered health care system and leeway to permit companies to introduce production bonuses if their workers agree to it, along with the modified health care deductibles.

These provisions - especially the company takeover of the so-called "union health card" system, a legacy of the late John L. Lewis and symbol of the union's former preeminence in the labor movement - are expected to trigger some strong opposition in the coalfields. But observers' initial reaction yesterday was that the industry concessions made the contract a fair-to-good bet to pass in a secret-ballot ratification vote.

UMW President Arnold Miller said he expected the 39-member union bargaining council, which rejected one contract offer before approving the pact that the miners rejected, would approve this proposed settlement. But he refused to predict whether the miners - in their present rebellious mood - would go along.

The tentative settlement was announced jointly by Miller and Pittston Coal Co. Chairman Nicholas T. Camicia, a former coal miner who was the industry's chief bargainer, in the lobby of the Capital Hilton Hotel.

It was in a 9th-floor suite of the hotel that the last round of negotiations had been conducted since Friday, without benefit of the federal mediators and Labor Department officials who had led previous bargaining efforts.

Anger at the Carter administration's "meddling" - including quiet efforts to split off some companies from the industrywide Bituminous Coal Operators Association and encourage company-by-company or regional settlements - was a major factor in bringing the two sides together last week.

The White House response to the agreement was a low-key expression of relief.

President Carter, who had gone on nationwide television to announce the earlier contract that was repudiated by the miners, issued a statement saying he was "pleased and encouraged" by the tentative settlement. "The welfare of our country requires a dependable supply of coal. A negotiated national contract is the best way to assure that supply," he said.

Earlier, the White House - in an apparent attempt to show some results from the Taft-Hartley order - put out word that 151 mines were operating this week that had been shut down last week, including 11 UMW mines. White House press secretary Jody Powell told reporters that the 151 mines are in Virginia, West Virginia, Alabama, Ohio, Pennsylvania and Illinois, and normally employ at least 3,500 workers.

Although all but a smattering of the 160,000 union strikers stayed home for the second day since the back-to-work order took full effect, government figures show a steady rise in coal production, mainly from non-UMW mines. The latest government figures show that production is about 56 percent of last year's, up from about one-third earlier in the strike.

In announcing the agreement, Camicia - whom union leaders credited for speaking their language and understanding miners' problems better than previous industry negotiators - took the lead.

"We think we have a package that would be very good for the union, very good for the country and get our miners back to work and the country back on its feet," he said. Miller, who is under fire from many rank-and-file miners who have begun a recall process against him, nodded but said nothing until reporters pressed him about ratification plans.

He said he would not move to compress the normal 10-day ratification process, although sources indicated later that a coalfield vote might come as soon as early next week.

After dodging a number of questions about the contract, Miller finally said, "After bargaining as long as we did, it's a pretty good contract."

He said he had "no idea" whether it would have an effect on the miners' defiance thus far of the Taft-Hartley order, which the government had indicated it hoped would produce at least some coal until a contract could be negotiated and ratified.

A Justice Department spokesman said late yesterday the government is still scheduled to go into federal court Friday to argue the merits of an 80 day "Cooling-off" injunction.

But the spokesman, Mark Sheehan, indicated the government could seek an extension of the seven-day temporary restraining order that was imposed by U.S. District Court Judge Aubrey Robinson last Thursday rather than seeking the longer-term injunction.

He conceded there could be a strategic advantage in holding off on the injunction while the miners are voting.

Attorney General Griffin B. Bell said after the restraining order was issued last week that the government would not abandon Taft-Hartley entirely until a settlement is in place because the law cannot be invoked more than once in a single-dispute.

The government moved slowly to enforce the back-to-work order out of concern that a gangbusters-style assault on the coalfields might jeopardize a negotiated settlement. But Bell on Monday night instructed law enforcement officials to "consider arrests" of anyone who tried to keep miners from returning to work and put union officials on notice they could face fines or jail if they refused to carry out the order.

In the coalfields yesterday, police reported some violence and arrests but no major confrontations.

Near Kingwood, W. Va., according to the Associated Press, four pickets were arrested at a power plant that had been burning non-union coal and charged with offenses unrelated to the Taft-Hartley Act. Pickets showed up in violation of the order in Colorado, Kentucky and West Virginia but there were no reports of arrests for picketing.

In Pennsylvania, the AP reported the club-carrying pickets traveled in a 150-car caravan to shut down non-union mines. "If any mines are open, they shut them down, then they move on," said State Police Maj. Homer Redd. "We've had some rocks thrown, but most of it's heckling."