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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.
- المادة
- Copper
- النوع
- Chalcopyrite concentrate from a porphyry, roughly 0.5% Cu ore grade
- حيث يبدأ
- Chile — Escondida, 3,100 m up in the Atacama
خطوة خطوة، وحدًّا حدًّا
Chile · Escondida, Antofagasta بحوزة BHP as operator, with Rio Tinto and JECO (شركة التعدين)
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.
لماذا هنا: A porphyry orebody, and desalinated seawater pumped 180 km uphill to process it.
Chile · Concentrator بحوزة BHP (شركة التعدين)
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.
ما الذي جرى للباقي: 984 tonnes to the tailings dam. Grinding is the largest single electricity consumer on any copper mine.
لماذا هنا: Always at the mine. Shipping 1,000 tonnes to recover 5 would be indefensible.
China · Antofagasta to Chinese smelter ports بحوزة Traders and smelters (متداول)
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.
لماذا هنا: Because the smelters are there. Chile smelts a minority of its own concentrate.
China · Guixi, Jiangxi بحوزة Smelter (المكرِّر)
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%.
ما الذي جرى للباقي: The captured sulfur becomes sulfuric acid — often sold onward to leach nickel or phosphate somewhere else entirely.
لماذا هنا: Smelting needs scale, an acid plant, an acid market and a permit. China assembled all four.
China · Tankhouse بحوزة Refiner (المكرِّر)
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.
ما الذي جرى للباقي: 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.
لماذا هنا: Refining follows smelting; the two are almost always on the same site.
China · Rod mill and cable plants بحوزة Cable and equipment makers (الشركة المصنّعة)
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.
لماذا هنا: Copper is one of the few materials here that can be recycled endlessly without losing quality. This tonne will outlive the mine.
هذا مثال تطبيقي. يتتبّع كمية ابتدائية محددة عبر معدلات عائد واسترداد نموذجية منشورة، مما يجعل النسب قابلة للتحقق؛ وهو ليس سجلاً لشحنة فعلية. وقد جُمعت وقائع المسار — الدول، والعمليات، وأسباب تعذّر معالجة المادة في مكان آخر — من تقارير متاحة للعموم.