It is probably just a translation issue, but I always thought the altar inside the courtyard, not the stone one referenced in the article, was made of acacia wood and covered in bronze. Brass and bronze have similar melting points with copper being the highest of the three. Maybe something to consider.
Exodus 27 New International Version (NIV)
The Altar of Burnt Offering
27 “Build an altar of acacia wood, three cubits[a] high; it is to be square, five cubits long and five cubits wide.[b] 2 Make a horn at each of the four corners, so that the horns and the altar are of one piece, and overlay the altar with bronze. 3 Make all its utensils of bronze—its pots to remove the ashes, and its shovels, sprinkling bowls, meat forks and firepans. 4 Make a grating for it, a bronze network, and make a bronze ring at each of the four corners of the network. 5 Put it under the ledge of the altar so that it is halfway up the altar. 6 Make poles of acacia wood for the altar and overlay them with bronze. 7 The poles are to be inserted into the rings so they will be on two sides of the altar when it is carried. 8 Make the altar hollow, out of boards. It is to be made just as you were shown on the mountain.
The Golden Altar of incense was also made of acacia.