Here we have the one of the many symbolic actions by Ezekiel. A voice, either Yahweh or his Spirit, told Ezekiel to be an expert model Lego builder of the siege of Jerusalem. Ezekiel, the son of man, was to take a brick and portray the city of Jerusalem. He was to put the siege works with a siege wall against this city. He was to put a ramp and camps against this city with battering rams all around it. Then he was to take an iron plate and make an iron wall between himself and the city, looking at it. Thus there was a state of siege, a sign for the house of Israel. Ezekiel was part of the exiles from 598 BCE before the taking of Jerusalem and the second captivity in 587 BCE.
Now Yahweh seems to indicate that there will be a second captivity when the rest of the sacred vessels will be brought to Babylon. They would stay there until Yahweh wanted to restore or bring them back to Jerusalem. Thus the vessels in Babylon were going to stay there, until Yahweh brought them back. In the meantime, the other sacred vessels from Jerusalem would be brought there also.