I used to live in St. Paul Mn. which at one time was a great railroad
town. There were several railroad repair shops in town. Every so often
I'd hear somebody say that they were going down to the railroad shop to
get some carbide slag to paint their concrete wall or floor with. The
railroads used a lot of acetylene and made their own.
After the calcium hydroxide absorbed CO 2 from the air it helped seal
the concrete, probably not as well as preparations made for that
purpose but the price was right.
It didn't take most people long to learn to wear rubber gloves working
with the stuff to keep the skin from being eaten off their hands.
Engineman

From: Don Foreman -
There is the minor matter of what to do with the approximately 207 lb
of calcium hydroxide left from making each 100 lb of acetylene. 100
lbs of gasoline is about 15 gallons, one fill at the pump. At one
fill per week, you'd have about 5 tons of white alkaline goo after a
year of operation. Perhaps one could treat the goo with HCL to make
calcium chloride and sell it to the highway departments in snow states
to rust out people's cars......thus getting support from the
automakers!