2012年(464)
分类: Delphi
2012-08-03 16:49:39
Jaw crusher sales from Kobelco Construction Machinery division were -18% from
JPY 97.7 billion (US$ 1.25 billion) to JPY 80.1 billion (US$ 1.02 billion),
while revenues for Kobelco Cranes fell -19% from JPY 11.8 billion (US$ 151
million) a year ago to JPY 9.5 billion (US$ 122 million).
The first important
reaction to occur is the calcining of limestone (calcium carbonate) into lime
(calcium oxide) and carbon dioxide, which occurs in the lower-temperature
portions of the kiln–up to about 1650°F (900°C). The second reaction is the
bonding of calcium oxide and silicates to form dicalcium and tricalcium
silicates. Small amounts of tricalcium aluminate and tetracalcium aluminoferrite
are also formed. The relative proportions of these four principal compounds
determine the key properties of the resultant portland cement and the type
classification (Type I, Type II, etc.). These reactions occur at very high
temperatures with the ingredients in molten form.Kobelco's sales of construction
equipment totalled JPY 89.6 billion (US$ 1.15 billion) in the first quarter of
the fiscal year from April to June, a -18% decline on the same period last year.
The company said that despite improved demand elsewhere in Asia, the slowdown in
China had hit its jaw crusher sales. It added that demand for crawler cranes was
up, but a move towards smaller models had seen revenues fall.
As the new
compounds cool, they solidify into solid pellet form called clinker. The clinker
is then ground to a fine powder, a small amount of gypsum is added, and the
finished cement is bagged or shipped bulk to ready mix concrete
plants.
Demand for equipment to help reconstruction efforts in Japan
increased domestic sales of both and cranes in the
first quarter, and Kobelco said demand was also strong in South East Asia.
However, it saw a fall in jaw crusher sales in China compared to a year ago.
"Monetary tightening in China, a major market, caused unit sales to go down
sharply in comparison to the same period last year, when demand was strong after
the Chinese Lunar New Year," the company said in a statement.
Concrete is
produced by mixing cement with fine aggregate (sand), coarse aggregate (gravel
or crushed stone), water, and–often–small amounts of various chemicals called
admixtures that control such properties as setting time and plasticity. The
process of hardening or setting is actually a chemical reaction called
hydration. When water is added to the cement, it forms a slurry or gel that
coats the surfaces of the aggregate and fills the voids to form the solid
concrete. The properties of concrete are determined by the type of
used, the additives, and the overall proportions of cement, aggregate, and
water.