Alloy

Mischmetal

The light rare earths alloyed together without being separated — the cheapest form rare earths come in, and the spark in every lighter flint.

Separating the rare earths from one another is the expensive part of the rare earth industry — they are chemically so alike that it takes hundreds of extraction stages. Mischmetal skips it. It is the light rare earths reduced together in whatever proportion the ore delivered them, roughly half cerium and a quarter lanthanum with neodymium and praseodymium making up most of the rest.

For a use that does not care which lanthanide it gets, that is an enormous saving, and it is why mischmetal was the first commercially significant rare earth product — decades before anyone separated them at scale.

Uses

Ferrocerium, the lighter flint, is mischmetal alloyed with iron. It is pyrophoric: shaved by a steel wheel, the fresh surface oxidises so fast that the fragments ignite, at temperatures well over 1,000 °C. Every disposable lighter and every fire steel works this way, and Carl Auer von Welsbach patented it in 1903.

It is also a steel additive. A small quantity scavenges sulfur and oxygen out of molten steel and modifies the shape of the inclusions that remain, which improves toughness — an unglamorous use that consumes a great deal of it.

And it was the negative electrode of the nickel-metal hydride battery, which powered hybrid vehicles and portable electronics before lithium-ion displaced it.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is used as

Alloying — application · added to molten steel to scavenge sulfur and oxygen and reshape the inclusions that remain, which improves toughness — an unglamorous use that consumes a great deal of it
Battery electrodes — application · the negative electrode of the nickel-metal hydride battery, which powered hybrid vehicles and portable electronics before lithium-ion displaced it

is composed of

Cerium — element · 45–55% · about half, because that is the proportion the ore delivers — mischmetal is the light rare earths left unseparated
Lanthanum — element · 20–30% · roughly a quarter, again as the ore gave it
Neodymium — element · 10–20% · most of the remainder
Praseodymium — element · 3–8% · the rest, and separating it out would cost more than the use requires
Iron — element · 0–30% · as ferrocerium, the lighter flint — the iron is what lets a steel wheel shave sparks off it

is produced by

Molten salt electrolysis — process · reduced from the mixed chlorides without separating the lanthanides first, which is the entire economic point of it

is sourced from

Monazite — mineral · reduced from the mixed light rare earths that monazite and bastnäsite deliver, in the proportions the ore happened to contain

Sources

Wikidata
Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
Material World
Our own writing

Questions this page answers

Where it comes from, and what it becomes

Follow Mischmetal back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

Mischmetal → is composed of (as ferrocerium, the lighter flint — the iron is what lets a steel wheel shave sparks off it) → Iron → is produced by (as pig iron, high in carbon and brittle until refined) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation → takes as input (the feedstock, and an unusual one in being free, unlimited and available anywhere — the cost is entirely the energy to liquefy it) → Air
Mischmetal → is composed of (about half, because that is the proportion the ore delivers — mischmetal is the light rare earths left unseparated) → Cerium → is produced by (a light rare earth, separated from its neighbours by countercurrent solvent extraction) → Rare earth separation → takes as input (the principal ore of the light rare earths, carrying all of them together) → Bastnäsite
Mischmetal → is composed of (most of the remainder) → Neodymium → is produced by (a light rare earth, separated from its neighbours by countercurrent solvent extraction) → Rare earth separation → takes as input (the principal ore of the light rare earths, carrying all of them together) → Bastnäsite
Mischmetal → is composed of (the rest, and separating it out would cost more than the use requires) → Praseodymium → is produced by (a light rare earth, separated from its neighbours by countercurrent solvent extraction) → Rare earth separation → takes as input (the principal ore of the light rare earths, carrying all of them together) → Bastnäsite
Mischmetal → is composed of (roughly a quarter, again as the ore gave it) → Lanthanum → is produced by (a light rare earth, separated from its neighbours by countercurrent solvent extraction) → Rare earth separation → takes as input (the principal ore of the light rare earths, carrying all of them together) → Bastnäsite
Mischmetal → is produced by (reduced from the mixed chlorides without separating the lanthanides first, which is the entire economic point of it) → Molten salt electrolysis → takes as input (after concentration, as one of the two routes to lithium chloride) → Lepidolite

These are the most distinct paths back. Mischmetal can be traced through others besides.

Downstream — what it becomes

Mischmetal → is used as (added to molten steel to scavenge sulfur and oxygen and reshape the inclusions that remain, which improves toughness — an unglamorous use that consumes a great deal of it) → Alloying
Mischmetal → is used as (the negative electrode of the nickel-metal hydride battery, which powered hybrid vehicles and portable electronics before lithium-ion displaced it) → Battery electrodes