Cohoes, NY: Norlite Shale Quarry and Processing

(Satellite)

I learned about this company because their processing plant has covered up Locks 5-7 of the Enlarged Erie Canal.

norliteagg_production

Obviously, this is a quarry.

Satellite

I did more research when I noticed that their processing plant has two rotary kilns.

Satellite

The seam of Normanskill Shale is 450 million years old and 3000' (610m) thick. After drilling and blasting, the shale is hauled to a crushing and screening facility that reduces the size to the range of 3/8" to 2". (Sizes smaller than 3/8" is sold as normal weight road base.) The shale then spends 45 minutes travelling through the rotary kiln increasing in temperature from 800 to 2000-2100 degrees Fahrenheit. It stays at the high temperature for a while where it undergoes "incipient fusion where the shale is in a semiplastic state. At this point, entrapped gases are formed and expansion results creating individual non-connecting air cells. The expanded shale is then discharged from the kiln onto an air quenched traveling grate cooler." The resulting clinker is then crushed and screened for the final products. [norliteagg_production]

norliteagg_norlite

"Norlite is a manufactured lightweight, porous ceramic material produced by expanding and vitrifying select shale in a rotary kiln. The process produces a consistent and predictable high quality ceramic aggregate that is structurally strong, physically stable, durable, environmentally inert, light in weight and highly insulative. It is a non-toxic, absorptive aggregate that is dimensionally stable and will not degrade over time.

"Norlite offers designers solutions to the challenges of reducing dead loads, lowering thermal conductivity of building products, improving fire ratings, enhancing soils, and treating wastewater, just to name a few."

It is used to make concrete. Because of the air bubbles, the concrete is lightweight and has a thermal insulation value more than twice normal weight concrete. The concrete is also more fire resistant, chemically inert and resistant to abrasion.

The advantage of using lightweight concrete on bridge decks is rather obvious. [norliteagg_bridges]

What is not obvious is the advantage of internal curing. If the norlite is soaked in water before it is mixed in the concrete, then the air pockets store water that facilitates the hydration process. [norliteagg_curing]