Sludge Watch ==> Calif - Mitsubishi cement kiln - tires, sludge, wood burned

[maureen.reilly at sympatico.ca]

Sludgewatch Admin

This story may be overstating the 'beauty' of burning tires, sewage sludge, 
or similar wastes in a cement kiln.  Kilns are not engineered with scubbers 
and air pollution controls.  There are all kinds of toxins in tires:
see: Hazards of Burning Tires:
http://www.portaec.net/local/tireburning/hazards_of_burning_tires.html

And using sewage sludge in a cement kiln will release the mercury and other 
toxins into the atmosphere...*ok...so will land application!

But there is another factor.  What will the tires and sludge do to the 
quality of the cement?
Many cement plants malfuction even using the normal ingredients - limestone 
and coal.  The use of a variety of 'alternative fuels' - with differing 
contaminant and combustion properties can lead to more plant upset 
conditions, more incomplete burns, more pollution and more batches of 
corrupted cement.  (see Lafarge - successful lawsuit when subdivision 
crumbled from crumby cement in Ottawa Ontario)  High phosphorus materials 
can change the properties of the clinker...resulting in construction 
failure.

http://eny.hut.fi/research/combustion_waste/publications/conference/NCRextab.pdf
..........................................................

http://www.vvdailypress.com/2006/114822463124203.html

Sunday, May 21, 2006

A beautiful waste Mitsubishi cement turns garbage into fuel



LUCERNE VALLEY — In a strange twist of chemicals, the cement-making process 
actually thrives on the materials humans shun: old tires, sewage and wood 
scraps from construction sites.

Mitsubishi Cement Corp. has been burning tires at its Cushenbury plant in 
Lucerne Valley since 1993, taking about 2 million tires a year out of 
landfills and using them to replace up to 15 percent of the coal used to 
fire the kiln.

‘The great thing about using waste tires is, one, they hold a lot of energy; 
two, the steel belts provide iron, and three, the ash is all absorbed into 
the cement,’ said David Rib, environmental manager at the plant.

The combustion process is so hot and so complete that there is no smoke 
coming from the kiln.

“People always have this vision of black smoke pouring out of everything,” 
said Bud Biggs, vice president at Mitsubishi Cement. “This does not happen 
in a cement kiln because you get complete combustion. Everything burns.”

In 1998, Mitsubishi began burning wet bio-solids, also known as sewage, from 
Los Angeles County. Because of the water in sewage, there is not much fuel 
benefit from burning it.

However, the ammonia in the sewage reacts with the nitrogen oxide gases 
emitted from coal burning, turning the “nox” to pure nitrogen.

“It actually reduces our ‘nox’ emissions,” Rib said.

Last week, Mitsubishi tested wood chips in the kiln. The material is cast 
off from construction sites and would normally end up in a landfill.

Eldon Heaston, executive director of the Mojave Desert Air Quality 
Management Agency, said the Mitsubishi plant goes through several tests 
whenever they begin using any waste fuel to make sure the process is not 
polluting the air.

“A cement kiln, by the way it’s designed, is actually a pretty good way to 
get rid of things that aren’t good for the environment because of the 
exceptionally high temperature and the residency time in the kiln,” he said. 
“Anytime they can back off the amount of coal they’re burning — it’s a 
pretty dirty fuel — you can expect that emissions would get better.”