vikone --
I believe that the material you have in mind is called "clinker."
Let me start with a simple definition.
"What is clinker?
When limestone, along with various additives of defined chemical
composition, is burnt under controlled conditions at a temperature
ranging between 1400 to 1600 degrees centigrade, the calcium oxide
present in the limestone reacts with alumina [aluminum oxide], iron
and silica [sand]. The hot semisolid mass is subjected to sudden
cooling, forming nodules of 10 to 20 mm. The black nodules thus
formed are called "clinker."
L&T Cement: FAQs
http://www.lntcement.com/quest1.html#2
"The clinker is composed of calcium silicates and calcium aluminates
and is finely ground and mixed with a small quantity of gypsum to
produce ... Portland cement."
Twinshare: Cement and Concrete
http://twinshare.crctourism.com.au/cement_and_concrete.htm
Now let me try to put "clinker" into the context of cement
manufacturing.
There are many descriptions of the cement manufacturing process
available online. I will draw from two of the most useful websites to
attempt a plain-English summary of that process -- including the role
of "clinker" -- and then direct you to various other sites and a
search strategy that can conveniently give you as much more detail
about that process as you would like.
The basic raw material of cement is limestone (calcium carbonate),
which is obtained from quarries, transported by truck to a (usually
nearby) cement manufacturing plant. There, the raw limestone is
crushed in several stages, reduced to rocks less than 25mm in diameter
and stockpiled.
Other raw materials, usually including shale (used for its aluminum
oxide, or "alumina"), iron ore and sand, are stockpiled separately.
The raw materials are combined, ground into a fine powder by steel
balls and stored in silos, where they are "homogenized" into a paste
of uniform composition. This paste is then fed into a kiln, which is a
rotating pipe of up to 6 meters in diameter and 60-90 meters long.
This is the most critical stage of the cement-making process.
The pipe is inclined so the paste slowly travels from one end of the
pipe to the other, where the heat source (burning pulverized coal) is
located. The paste is heated to about 1450 degrees centigrade, which
results in a process called "clinkering," in which the solid black
nodules called "clinker," drop into coolers and are sent to silos for
further storage.
The final stage of cement production occurs in a "grinding mill,"
where the "clinker" is combined with gypsum (calcium sulfate) and
crushed into a fine, homogeneous powder. The gypsum is necessary in
order to avoid instantaneous "setting" of the cement when water is
added. The cement is then stored for shipment to end users.
The sources for this summary can be found here:
European Cement Association: The Cement Manufacturing Process
http://www.cembureau.be/About/Cement%20Industry/Cement%20manufact%20process.htm
PPC Cement: Manufacturing Process
http://www.ppc.co.za/Cement/c_cement_manprocess.asp
Additional Sites:
The following sites provide additional detail on the cement
manufacturing process:
Unicon Concrete: Portland Cement Manufacturing
http://www.carolinapumping.com/education/elementary/cement_manufacturing.html
Portland Cement Association: Concrete Basics
http://www.portcement.org/cb/concretebasics_history.asp
This site discusses the use of alternative fuels in cement
manufacturing:
Cement.org: Alternative Fuels Factsheet
http://www.cement.org.au/environment/alternative_fuels_factsheet_right.htm
Google Search Terms
cement "manufacturing process"
://www.google.com/search?sourceid=navclient&q=cement+manufacturing+process+
cement "manufacturing process" clinker OR clinkering
://www.google.com/search?q=cement+manufacturing+process+clinker+OR+clinkering&hl=en&lr=&ie=UTF-8&start=20&sa=N
Since the word "clinker" corresponds to the phonetic spelling of
"klingair" in your question, I am confident that this is the material
you are interested in. If any of the information needs
clarification, please let me know before rating this answer.
markj-ga |
