The journey from tawny earth to copper wire begins with an explosion. Or 2,697 explosions, to be precise. At the 1,100-acre main pit of Kansanshi copper mine in northern Zambia, a lattice of six-inch blast holes punctuates the ribboned moonscape. At 3 p.m., the ground erupts in an echelon pattern, sending plumes of dust skyward.  Cue the arrival of the world’s largest electric dump trucks, which haul away the rubble to be ground to a fine powder. The ore is then concentrated via chemical