How feldspar is mined

Feldspar is the most abundant mineral group in the crust, and glassmakers buy it for the aluminum it supplies.

stations: 5
things downstream: 11

The short version

Feldspar mills chase iron out of pale rock. Ore quarried from pegmatite or granite-like dikes is crushed and rod-milled to under 20 mesh, a coarse grain with few fines. Slimes wash off, then acid flotation lifts away mica and iron-bearing minerals, and a second float raises feldspar away from quartz. The concentrate is filtered and dried, then sold to glass and ceramics makers.

Quarry the pale rock

Ore generally comes from open pits in pegmatites or large dikes, mixed with quartz, mica and garnet. Trucks haul it to the mill.
Crush and rod-mill

Two stages of crushing feed a rod mill, which makes a granular product with little slime. Markets want minus 20 mesh, and a spiral screen removes coarse mica and hard quartz pieces as waste.

minus 20 mesh
Wash out the slimes

Rake classifiers and a hydroclassifier send the finest particles to waste, since the float needs a slime-free feed. The sand then gets intense stirring with acid reagents in a heavily built conditioner.
Float off mica and iron

In an acid circuit, mica, garnet and other iron-bearing minerals rise in the froth and go to waste. Some plants float the mica first and the iron minerals afterward.
Float and dry the product

A final acid float lifts the product away from quartz. Classifiers and vacuum filters take it down to 7 to 9% moisture, a rotary dryer removes the rest, and a screen catches stray scale on its way to the silos.

End of the lineFeldspar Next it goes into ceramic, porcelain, toilet and 2 more.

Worth repeating

About 66% of feldspar in the United States is used in glassmaking.
In ceramics, feldspar acts as a flux, helping glassy material to form in the body of the ware during firing.
Roughly 60% of Earth's crust is feldspar.