An attempt to rescue 33 Chilean miners trapped deep underground will begin at midnight on Wednesday (0300 GMT), Mining Minister Laurence Golborne says.
A test of the rescue capsule has been carried out successfully, descending almost the whole way down the 622m (680yd) shaft, engineers say.
Earlier, the top 90m was reinforced with metal casing to prevent crumbling.
The miners have been trapped since a collapse in the mine on 5 August, but were reached by a drill on Saturday.
The “Plan B” drill that reached the miners left the San Jose mine, near the town of Copiapo, to a rousing reception on Monday.
The drill was driven away surrounded by crowds of photographers and cheers by hundreds of people across the site.
Shortly afterwards, officials briefed the media on the latest developments in the bid to bring the miners to the surface.
Chief engineer Andre Sougarret said a formal test of the shaft had been successful, with the specially constructed Phoenix rescue capsule barely registering a scratch as it travelled up and down the tunnel.
The top 90m have been lined with metal to prevent the crumbling surface rocks from breaking away during the rescue.
But experts say the rest of the escape shaft is dug through solid rock and will not break up.
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