Grimy with the dust of shattered concrete, his eyelids swollen from lack of sleep, the hard-hatted miner emerged late this afternoon from the stone portal of the collapsed 19th-century apartment house.

Inside, rescue workers were still hoping today that Luis Ramon Navarrete Maldonado, 9, could remain trapped alive 15 days after his grandfather's home fell on him in the earthquake.

"It could be 20 minutes, or it could be 10 hours," the miner said, shrugging. He refused to give his name. "We're not looking for publicity, we just want to get the boy," he said.

In the confusion that has characterized much of the massive volunteer rescue effort here since the Sept. 19 earthquake, workers at the scene today offered conflicting stories of the child's condition and the prospects for his rescue.

A team of rescue specialists from the Dade County, Fla., Fire Department arrived at 6 p.m. and began working. They said there were no indications that the child was still alive but added they would continue to assist the rescue effort as long as the Mexicans wanted.

Some said the child had been physically sighted by the miners, but remained trapped behind huge blocks of masonry and flattened rolls of textiles from a neighboring factory that collapsed on the house. The child actually spoke to the miners at 11 this morning, responding "yes" when asked if he was there, according to Jose Negrete, a volunteer acting as spokesman for the ad hoc team of miners, Mexico City police, mountain rescue brigadiers and Algerian rescue experts.

"No, I'm sorry, I don't think it's so," demurred Antonio Sosa, 22, one of the mountain rescue volunteers. "You can't see anything under there, and you can't hear anything. Maybe the miners who were at the front of the tunnel can, but I doubt it."

Col. J.D. Ramirez Garrido, one of the Mexico City police officials coordinating the rescue effort, also quietly expressed concern that the hopes raised for the boy's rescue may have been false. The reports this morning of voice contact with the child were untrue, he said.

"I don't know; they say he is all right," said Francisco Andraka, the boy's great-uncle, who also lived in the wrecked building. "You have to have faith."

Workers later snaked an air hose to the site where the boy is believed to be trapped, Carlos Malbran, a volunteer, said.

All the residents of the structure's 18 apartments had escaped before the building fell, Andraka said, except Luis Ramon and his grandfather, Alberto Maldonado. Luis and his family, who until mid-September had lived on the Caribbean resort island of Cozumel, were visiting their family on the way to the Pacific coast, where Luis' father, Mauricio, was to take a job at a hotel in Zihuatanejo.

Luis' parents and two sisters fled the building safely, but Luis and his grandfather apparently were trapped in the room where they were sleeping. Andraka, who has waited on the street for the past 15 days, said he had been told the boy will be taken out before Saturday morning. "This is a vigil," he said.

It seemed as if all Mexico was waiting today for Luis Ramon to be brought out alive. Scores of cameramen and reporters have been standing outside the building since early morning. Afternoon newspapers carried headlines proclaiming, "Luis will be saved!" and "They haven't got him out yet."

At the site, the rescue effort was personally directed by Gen. Ramon Mota Sanchez, the Mexico City police chief, who spoke to a stream of visiting dignitaries. U.S. Ambassador John Gavin and his wife, Constance, visited the building today.

As they have since the beginning of the rescue efforts, volunteer miners who normally earn $6 a day in the silver mines of Taxco and Pachuca today were doing most of the dirty work. The "mole men," as the miners are popularly known, have earned the respect of the foreign rescue specialists for their expertise, developed in rescuing coworkers during cave-ins.

"If they get the boy out, it will be simply because these miners won't give up," Sosa said. "They seem to be able to tunnel into anything."

Two of the three rescue tunnels being bored toward the child have already collapsed, however. Mexican rescue workers, many of whom have labored without pay here and at other sites throughout the past two weeks, appeared grim and fatigued this afternoon rather than animated by the prospect of rescuing another survivor. There was the universal recognition that whether the boy is pulled out alive or dead, this rescue effort almost certainly marks the end of the long, desperate search for survivors.