実際に動いているもの
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.
- 素材
- Copper
- 種類
- Chalcopyrite concentrate from a porphyry, roughly 0.5% Cu ore grade
- 起点
- Chile — Escondida, 3,100 m up in the Atacama
工程ごと、越境地点ごとに
Chile · Escondida, Antofagasta 保管者 BHP as operator, with Rio Tinto and JECO (採掘会社)
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.
なぜここか: A porphyry orebody, and desalinated seawater pumped 180 km uphill to process it.
Chile · Concentrator 保管者 BHP (採掘会社)
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.
残りはどうなったか: 984 tonnes to the tailings dam. Grinding is the largest single electricity consumer on any copper mine.
なぜここか: Always at the mine. Shipping 1,000 tonnes to recover 5 would be indefensible.
China · Antofagasta to Chinese smelter ports 保管者 Traders and smelters (トレーダー)
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.
なぜここか: Because the smelters are there. Chile smelts a minority of its own concentrate.
China · Guixi, Jiangxi 保管者 Smelter (精製業者)
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%.
残りはどうなったか: The captured sulfur becomes sulfuric acid — often sold onward to leach nickel or phosphate somewhere else entirely.
なぜここか: Smelting needs scale, an acid plant, an acid market and a permit. China assembled all four.
China · Tankhouse 保管者 Refiner (精製業者)
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.
残りはどうなったか: 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.
なぜここか: Refining follows smelting; the two are almost always on the same site.
China · Rod mill and cable plants 保管者 Cable and equipment makers (製造業者)
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.
なぜここか: Copper is one of the few materials here that can be recycled endlessly without losing quality. This tonne will outlive the mine.
これは計算例である。公表された標準的な歩留まりと回収率を用いて、明示された出発量を追うものであり、比率は検証可能だが、特定の荷物の記録ではない。経路に関する事実——どの国を経由するか、どのような工程を経るか、なぜその素材を他の場所では処理できないか——は公開情報から編集している。