Portland, Blended, and Other Hydraulic Cements - Design and Control of Concrete Mixtures - page 25

Table 2-1. Sources of Raw Materials Used in Manufacture of Portland Cement

Calcium Iron Silica Alumina Sulfate

Alkali waste Blast-furnace flue dust Calcium silicate Aluminum-ore refuse* Anhydrite

Aragonite* Clay* Cement rock Bauxite Calcium sulfate

Calcite* Iron ore* Clay* Cement rock Gypsum*

Cement-kiln dust Mill scale* Fly ash Clay*

Cement rock Ore washings Fuller's earth Copper slag

Chalk Pyrite cinders Limestone Fly ash*

Clay Shale Loess Fuller's earth

Fuller's earth Marl* Granodiorite

Limestone* Ore washings Limestone

Marble Quartzite Loess

Marl* Rice-hull ash Ore washings

Seashells Sand* Shale*

Shale* Sandstone Slag

Slag Shale* Staurolite

Slag
Traprock
Note: Many industrial byproducts have potential as raw materials for the manufacture of portland cement.
*Most common sources.

Fig. 2-6. Limestone, a primary raw
material providing calcium in making
cement, is quarried near the cement
plant. (59894)

Fig. 2-8. Rotary kiln (furnace) for manufacturing portland cement clinker. Inset
view inside the kiln. (58927, 25139)

of calcareous (cal-
cium carbonate
bearing) material,
such as limestone,
and an argillaceous (silica and alumina) material such as
clay, shale, fly ash, or blast-furnace slag. Either a dry or a
wet process is used. In the dry process, grinding and blend-
ing are done with dry materials. In the wet process, the
grinding and blending operations are done with the mate-
rials mixed with water in a slurry form. In other respects,
the dry and wet processes are very much alike. Fig. 2-4
illustrates important technological developments that can
improve significantly the productivity and energy effi-
ciency of dry-process plants.
After blending, the ground raw material is fed into the
upper end of a kiln (Fig. 2-8). The raw mix passes through

the kiln at a rate controlled by the slope and rotational
speed of the kiln. Burning fuel (powdered coal, new or
recycled oil, natural
gas, rubber tires, and
by-product fuel) is
forced into the lower
end of the kiln
where temperatures
of 1400°C to 1550°C
change the raw
material chemically
into cement clinker,
grayish-black pel-
lets predominantly
the size of marbles
(Fig. 2-9). Fig. 2-10

Fig. 2-7. Quarry rock is trucked to the
primary crusher. (59893)

Fig. 2-9. Portland cement clinker is
formed by burning calcium and sil-
iceous raw materials in a kiln. This
particular clinker is about 20 mm ( 3 ⁄ 4
in.) in diameter. (60504)