The flowsheet families at a glance

The industry runs a small number of recurring flowsheet archetypes, and once you can name them you can place almost any real plant inside one. They are not eight different chemistries so much as eight different arrangements of the same mechanism set — leach, separate, purify, recover — keyed to a commodity. This page walks all eight in a paragraph each, naming the mechanisms each one composes so that later modules have somewhere to land.

Gold (CIL/CIP) is leach–adsorb–elute–electrowin. Finely ground ore is leached in agitated tanks; the dissolved gold is adsorbed straight from the slurry onto activated carbon (the mechanism of Module 6.4); the loaded carbon is eluted and the gold electrowon (7.1), and the stripped carbon regenerated in a kiln (6.5). The Merrill-Crowe variant swaps adsorption for zinc cementation (6.3). It is the archetype where adsorption from a pulp, rather than a clarified solution, defines the circuit.

Copper (SX-EW) is heap leach–solvent extraction–electrowinning. Acid percolates through a stacked heap (the leaching family of 4.4); the pregnant solution is upgraded and purified by solvent extraction (6.6), which moves copper from a dirty leach liquor into a clean electrolyte; that electrolyte is electrowon to cathode (7.1). The concentrate route instead pressure-oxidises sulfides (3.3/4.6) before leaching.

Zinc (RLE — roast–leach–electrowin) starts with a pyro step: the sulfide concentrate is roasted to oxide (3.2), which sulfuric acid then leaches (4.3); the solution is purified by cementation with zinc dust (6.3) before electrowinning (7.1). It is the clean example of a hybrid interface — a roaster feeding an aqueous circuit.

Nickel laterite (HPAL) is high-pressure acid leach–neutralise–precipitate. Ore is leached in an autoclave at temperature and pressure (4.6); the liquor is neutralised in stages (6.2) and the nickel and cobalt precipitated as an intermediate (7.4). It is the archetype where the leach itself is the severe unit operation.

Alumina (Bayer) is digestion–clarify/wash–seeded crystallisation–calcination. Bauxite is digested in hot caustic (4.3/4.6); the liquor is clarified and the residue washed counter-currently (Module 5, the CCD chain); alumina is crystallised by seeding (7.3) and calcined to product (3.2). It is the great counter-current-washing flowsheet.

Lithium runs two routes. The hard-rock route calcines spodumene and acid-bakes it (3.2), water-leaches the sulfate (4.3), purifies by precipitation and ion exchange (6.2/6.7), then concentrates and carbonates by solubility (7.3) with a re-dissolution polishing loop (6.9). The brine route concentrates by solar evaporation (7.3), removes impurities, and carbonates — and direct lithium extraction is an adsorption play (6.4).

Uranium is leach–ion-exchange or solvent-extraction–precipitate (4.x, 6.6/6.7, 6.2). Battery recycling — black mass — is the newest family, dissolving spent cathode and rebuilding precursors (4.3, 6.x, 7.4).

Eight commodities, one mechanism inventory. Module 9 builds each of these as a full annotated family page; this survey is the preview, and the spine figure the rest of the path fills in.