The NFL began reopening for business after player leaders unanimously began the process of approving a new 10-year collective bargaining agreement with the league Monday.

After the final differences were worked out Monday at the downtown D.C. offices of the NFL Players Association, the sport announced plans to resume operations in stages, with players returning to teams’ training facilities Tuesday. Some signings of players are to begin Tuesday, and some teams begin their training camps Wednesday.

“It’s been a long time coming,” NFL Commissioner Roger Goodell said. “Football is back, and that’s the great news for everybody.”

The 41 / 2-month lockout will end officially if the labor agreement is ratified by a majority of the close to 2,000 NFL players, which is considered a virtual certainty.

“Do we see any problems on the horizon for [approval by] the group of players?” said DeMaurice Smith, the executive director of the NFL Players Association. “No. . . . I don’t believe that there’s going to be a problem with the unity of the players getting together. . . . Our job is to get it done.”

Players are to be allowed into teams’ training facilities at 10 a.m. Tuesday to undergo physicals and participate in voluntary workouts. Teams can make trades Tuesday and sign their rookies to contracts contingent on the players’ ratification. Teams can negotiate with free agents Tuesday but can’t sign those players until 6 p.m. Friday.

Hundreds of players are eligible for free agency after trades and free agent signings were on hold during the lockout, which began March 12. So there will be a mad scramble for teams to assemble rosters and players to find jobs.

“The best word for it is chaos,” said fullback Tony Richardson, a member of the players’ executive committee. “I’ll be a free agent. It’s going to be interesting.”

Ten NFL teams are scheduled to open their training camps Wednesday. Another 10, including the Washington Redskins, are to open camps Thursday, then 10 more Friday and the remaining two Sunday. The preseason is to begin Aug. 11; the regular season is scheduled to begin Sept. 8.

Goodell and Smith stood side by side at Monday’s announcement and shook hands at one point. Indianapolis Colts center Jeff Saturday hugged Robert Kraft, the owner of the New England Patriots, after praising Kraft, whose wife Myra died last week after a battle with cancer. Kraft’s eyes became teary as Saturday spoke.

Goodell said both sides have to make sure fans understand that “we are sorry for the frustration that we put them through over the last six months,” and Kraft issued a public apology to the sport’s followers.

Kraft also said: “I hope we gave a little lesson to the people in Washington because the debt crisis is a lot easier to fix than this deal was.”

The players’ executive committee and the player representatives from the 32 teams recommended Monday that the players settle their antitrust lawsuit against the owners filed in March. They also recommended that the players re-form their union, which they dissolved the day before the lockout began, to finish the labor agreement, because issues such as drug-testing matters must be collectively bargained by a union.

The two sides signed the lawsuit settlement Monday, with Goodell and Kraft being accompanied to the NFLPA offices by owners John Mara of the New York Giants and Jerry Richardson of the Carolina Panthers. The collective bargaining agreement must receive final approval by the players by Aug. 4 or the settlement of the lawsuit is voided.

The owners voted, 31-0 with one abstention by the Oakland Raiders, Thursday in Atlanta to approve the collective bargaining agreement.

The labor agreement does not include an opt-out clause, a demand the players dropped late Monday morning.

“I think at the end of the day, neither side got everything they wanted, but I think we did achieve a deal that will stand the test of time and be in the best interests of our league, our players, our clubs and our fans,” Mara said.

The dispute ends with the sport having lost only one preseason game, and Smith and Goodell have overseen their first deal after inheriting a long-standing labor peace from their predecessors, late union chief Gene Upshaw and former commissioner Paul Tagliabue.

“I think that if we don’t have a good relationship, it hurts the game and the business of football,” Smith said. “And I can tell you I’m not sure that any two people have ever come together in a more compressed, public, interesting time than Roger and I.”

Said Goodell: “Relationships are built on respect, and De and I have that for one another.”

The deal includes a salary cap system by which players will receive an average of at least 47 percent of the sport’s revenues, now about $9.3 billion annually and expected to rise sharply in future seasons, over the 10-year duration of the agreement.

The salary cap is to be set at $120.4 million per team for the upcoming season, not counting $22 million per club in player benefits. There is a salary cap exception by which a team may borrow up to $3 million in cap space from a future season to sign players this season. There are new payroll minimums requiring the teams to collectively spend 99 percent of the salary cap in cash over the next two seasons, and 95 percent in subsequent seasons.

The requirement for a player with an expired contract to be eligible for unrestricted free agency is restored to four seasons of NFL experience, down from the six seasons required last year in a season without a salary cap. Teams can continue to use franchise-player tags and transition-player designations to restrict some players’ free agent mobility.

A new rookie pay system curbs the amount of guaranteed money in rookies’ contracts and stipulates contract lengths. Rookies selected in the NFL draft are to sign four-year contracts, with fifth-season options for first-round draft choices. Undrafted rookies are to sign three-year deals.

The new collective bargaining agreement keeps the regular season at 16 games per team. The players had opposed the league’s previous proposal to increase the season to 18 games per club. The deal stipulates the players must agree to any future switch to a longer season. The agreement includes cutbacks in offseason workouts and reductions in hitting in practices during training camp and the season.

The deal ends federal court oversight of the sport’s labor situation and includes a $620 million “legacy fund” for retired players over the 10-year duration of the agreement.

Teams’ training camps rosters are expanded to 90 players per team this summer.