实际流转的物质
Sulfide copper has to be smelted, and more than half the world's smelting capacity is on the other side of the Pacific. So Chilean concentrate — about 30% copper and 70% something else — sails 19,000 km to be turned into metal, and the by-products in it become somebody else's gold, silver and tellurium.
- 材料
- Copper
- 品种
- Chalcopyrite concentrate from a porphyry, roughly 0.5% Cu ore grade
- 起点
- Chile — Escondida, 3,100 m up in the Atacama
逐步追踪，逐境跨越
Chile · Escondida, Antofagasta 持有方 BHP as operator, with Rio Tinto and JECO (矿业公司)
Moving a mountain for half a percent
Drilled, blasted and hauled from an open pit. At about 0.5% copper, 995 kg of every tonne is waste before processing even begins.
为何选择此地: A porphyry orebody, and desalinated seawater pumped 180 km uphill to process it.
Chile · Concentrator 持有方 BHP (矿业公司)
Grinding and floating
Ground to a powder and floated: air bubbles carry the sulfide minerals to the surface while the rock sinks. The result is a concentrate of about 30% copper.
其余部分的去向: 984 tonnes to the tailings dam. Grinding is the largest single electricity consumer on any copper mine.
为何选择此地: Always at the mine. Shipping 1,000 tonnes to recover 5 would be indefensible.
China · Antofagasta to Chinese smelter ports 持有方 Traders and smelters (贸易商)
Down to the coast and across the Pacific
Concentrate moves by truck or slurry pipeline to the port, then in the hold of a bulk carrier. Treatment charges — what the smelter is paid to process it — are negotiated annually and are one of the industry's most watched numbers.
为何选择此地: Because the smelters are there. Chile smelts a minority of its own concentrate.
China · Guixi, Jiangxi 持有方 Smelter (精炼商)
Smelting
Melted with oxygen. Iron and sulfur oxidise away; the sulfur is captured as sulfuric acid rather than released. What is left is blister copper at about 98%.
其余部分的去向: The captured sulfur becomes sulfuric acid — often sold onward to leach nickel or phosphate somewhere else entirely.
为何选择此地: Smelting needs scale, an acid plant, an acid market and a permit. China assembled all four.
China · Tankhouse 持有方 Refiner (精炼商)
Electrorefining, and the slime at the bottom
Blister is cast into anodes and dissolved electrolytically over about two weeks; pure copper plates onto cathodes. Gold, silver, selenium, tellurium and platinum-group metals do not dissolve and settle as anode slime.
其余部分的去向: That anode slime is where a large share of the world's tellurium and selenium comes from. The by-products of this step are a whole industry.
为何选择此地: Refining follows smelting; the two are almost always on the same site.
China · Rod mill and cable plants 持有方 Cable and equipment makers (制造商)
Rod, wire, and a grid
Cathode is melted and drawn into rod, then wire, then cable. 4.6 tonnes is roughly the copper in one large wind turbine, or a few hundred metres of subsea export cable.
为何选择此地: Copper is one of the few materials here that can be recycled endlessly without losing quality. This tonne will outlive the mine.
本文为示例演算，以公开的典型产率和回收率对既定起始量逐步推算，各比例可供核验；这不是某批具体货物的记录。路线事实——途经哪些国家、经历哪些工序，以及为何该材料不能在其他地方简单处理——均来源于公开报道。