Egyptian zabbâlîn (the word derives from zabbâl, waste) do not just collect and sort waste: they also transform some of the materials they collect, such as aluminium. They use a very simple system to melt the aluminium: a refractory cement crucible with a heating system fuelled by used oil. When the crucible is heated through, the workers fill it with cans: the heat is intense, as shown by the photograph. Liquid aluminium is then poured into bar-shaped moulds and sold on at a good price.