实际流转的物质
Bauxite is red soil. It is refined into alumina, and alumina is smelted into aluminium by passing an enormous electric current through it. Because that last step is essentially electricity in solid form, the smelter is built next to cheap power rather than next to the mine — often on a different continent.
- 材料
- Bauxite
- 品种
- Gibbsitic bauxite, roughly 45% alumina, low silica
- 起点
- Guinea — The Boké plateau, part of the largest bauxite reserve base in the world
逐步追踪，逐境跨越
Guinea · Boké, Guinea 持有方 Mining consortia with the Guinean state (矿业公司)
Scraping the plateau
Bauxite lies at or near the surface under a thin overburden. It is ripped and loaded — no blasting, no grinding, no flotation. The simplest large-scale mining there is.
为何选择此地: Tropical weathering over millions of years made this. West Africa and northern Australia have most of it.
China · Kamsar, then Chinese and Gulf refineries 持有方 Traders and refiners (贸易商)
Rail to the coast, then a Capesize
Railed to a purpose-built port and loaded onto bulk carriers. Guinea ships hundreds of millions of tonnes a year of what is, physically, dirt.
为何选择此地: An export ban would force refining onshore — several countries have tried exactly that with different minerals.
China · Alumina refinery 持有方 Refiner (精炼商)
The Bayer process
Digested in hot caustic soda under pressure. The alumina dissolves; the iron and silica do not, and settle out as red mud. The dissolved alumina is then precipitated and calcined to a white powder.
其余部分的去向: Red mud is the largest single waste stream in the metals industry by volume, and it is caustic. Storing it safely is the defining problem of this step.
为何选择此地: Refineries sit near ports and near smelters. Some are in Guinea now, but most of the capacity is not.
United Arab Emirates · Smelter, wherever power is cheap 持有方 Smelter (精炼商)
Electricity, made solid
Alumina is dissolved in molten cryolite at about 960 °C and an enormous direct current is passed through it. Aluminium collects at the bottom; the carbon anodes are consumed and must be constantly replaced.
其余部分的去向: Roughly 125 tonnes of carbon anode is burned away — and that carbon started life as petroleum coke, from an oil refinery.
为何选择此地: Iceland, the Gulf, Quebec, Siberia, Yunnan. All the same answer: cheap, reliable, uninterruptible electricity.
Germany · Rolling and extrusion mills 持有方 Fabricators (制造商)
Frames, cans, cables, car bodies
Cast into billet and slab, then extruded or rolled. Recycled aluminium needs about a twentieth of the energy of primary, which is why scrap is worth so much.
为何选择此地: Four tonnes of Guinean soil for one tonne of metal — and once it exists, it can be melted and reused indefinitely.
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。