Native miners, from the Negeb and Midian, with an Egyptian scribe noting production quotas, sprinkle dressed copper ore into the fire of the crucible. Slag residue in the form of rings lie on the ground. A man works a bellows to maintain the heat intensity. Perhaps the smoke plumes from the crucibles, running day and night are behind the bible's imagery of a pillar of cloud by day and fire by night ? Such plumes might serve to lead visitors to the Timna area.
(p.53, "Streamlining an Age-Old Smelting Process." Percy Knauth.
The Metalsmiths[The Emergence of Man Series]. New York. Time-Life Books. 1974)