ILMA Compoundings October 2017 - 34

company to construct the first U.S. recycling facility for
lithium-ion vehicle batteries and, in 2015, the facility in
Lancaster, Ohio, began operation.

Lithium Use in the Grease Industry
Different grease viscosities are used based on the speed and
load of an application. "When specifying the lubricant, the
thing that is important is that it has the viscosity to flow
and do the lubricating in the way it is supposed to. Where
the thickener becomes a question is when you're trying to
control how it stays in the application," Sander said.
Thickeners are used to keep grease in places where a liquid
would leak out. "If there are certain bearing applications
that are apt to leak, then oftentimes the grease is a better
lubricant," Sander said, adding that thickeners are also used
in greases in high-temperature applications.
NLGI consistency grades range from Grade 000 up through
Grade 6. Sander said the most common grade is NLGI Grade
2, which, on average, consists of about 15 percent thickener
depending on how the manufacturer produced the grease. "If
you're doing lithium 12-hydroxystearate, you get the hydrogen bonding, so you can use less thickener," he explained.
Manufacturers use a penetration test in which a cone is
dropped into a cup of grease to get the NLGI rating. "You
measure how far the cone sunk by a tenth of a millimeter
into the grease's surface. It is sort of like the grease viscosity,
but you're not actually measuring the flow properties, so you
call it a penetration."
The grease industry uses lithium hydroxide, which is a
hydrated version of lithium carbonate, Sander said. "When
you're forming a soap-type grease, you'll usually react that
lithium oxide with a fatty acid," Sander said. "The lithium
hydroxide is typically reacted with 12 hydroxy stearic acid
or just stearic acid. Both of these are an 18 carbon fatty acid,
also often called a carboxylic acid."

Lithium Alternatives
If a lithium shortage occurred, Sander said, there are lithium
replacements. "Back a long time ago, the most common
soap types were lye greases, which were sodium-thickened
greases. They work pretty well unless you have a lot of water
near the application," he said, explaining that if a car were to
drive through a puddle, for example, the water could wash
away lubricants in the wheel bearings.
Sander said the easiest alternative for Lubrication Engineers to shift to would be aluminum greases. Aluminum
soaps are more difficult, so many companies chose not to go
that route. "They are more expensive, but that may change
as lithium price comes up," Sander said.
"I would imagine the majority would shift to calcium greases," Sander said, adding that calcium soaps are gaining ground.
"Calcium stearate, calcium oxalates and calcium sulfonates are
probably your most attractive, price-wise, to replace lithium.
The downside of them is that it typically takes more soap to get
the same amount of thickening efficiency," Sander said.

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NLGI reported that greases made with calcium soap
reached 10.7 percent of production worldwide and those
made with aluminum soap reached 3.2 percent. Sander said
polyurea greases are another option, and NLGI reported
that greases made with polyurea made up about 6 percent of
greases produced worldwide.
"The auto industry likes them a lot, and they are used in
our industry. Because it is a non-soap grease, you have no
metal challenges. The downside is they have less of a tendency to be friendly to other greases getting mixed into them,"
Sander said. "You could take a polyurea grease from us and
one from another manufacturer and mix them together and
they're probably going to be incompatible."
Sander said manufacturers can use the same equipment to
make lithium, calcium and aluminum soaps. Some calcium
complex greases require kettles that are somewhat sealable
because of flammability concerns, but it is largely the same
equipment, Sander said.
USGS said substitutions for lithium compounds are also
possible in batteries, ceramics and manufactured glass. Examples are calcium, magnesium, mercury and zinc as anode
material in primary batteries and sodic and potassic fluxes in
ceramics and glass, the agency said.
Long is a freelance writer and journalist. She can be reached at
925-750-7163 or mindy@mindylong.com.

http://www,biederman.ca http://www.ILMA.ORG

ILMA Compoundings October 2017

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