The History of Portland Cement (Part 2)

Perhaps the most important feature of the county’s industrial progress is the rapid growth of the cement industry. Patented in England less than a century ago, it was not until early in the seventies that Portland Cement was manufactured in America. Since then the annual output has shown an actual increase each year to date, thereby contributing largely to the marvelous growth of the industries engaged in the production of non-metallic structural materials, such as brick, tile and building stone, and far outstripping any of these, its rivals. Characteristic of a young and growing industry the financial depression of the county, experienced at intervals since the inception of the industry in 1870, has in no way retarded its growth, the annual output continuing to increse through good and bad years alike until in 1910 the annual total of 76,549,951 barrels is reached.

That an amount which alone exceeded the entire nation’s output a short three decades ago, was consumed in the construction of the Thebes Bridge, Thebes, Illinois (see photo), completed in the year 1905, is a striking example of the rapid advancement of concrete as a structural material.

The immense production of Portland Cement today has been made possible by the radical changes in the machinery and equipment used in its manufacture. In the early days, when stationary kilns and millstones were in vogue, there was no perceptible increase in American production, and while practically the same machinery was used abroad, foreign manufacturers had at least the advantage of cheap labor, which enabled them to successfully market the product in this country.  For example, during the year 1880 approximately 187,000 barrels were imported, against  42,000 barrels of domestic manufacture. With the advent of the rotary kiln and more modern grinding machinery, several years later, however, American production steadily increased, but it was not until the year 1897 that it exceeded the imports of foreign cement.

Since then the American Portland Cement industry has grown by leaps and bounds, while the imports of foreign cement, which at no time reached the 3,000,000-barrel mark in any one year, has practically remained stationary, and has consequently ceased to be considered a competitor in the American market.

Briefly stated, Portland Cement is a manufactured product, obtained by burning a finely ground artificial mixture consisting essentially of lime, silica, alumina and iron oxide in certain definite proportions. These properties are combined in the burning, which takes place in kilns designed for the purpose, at a temperature approaching 3000 degrees F. The product of the burning is called “clinker,” which after grinding is Portland Cement. This would seem a very simple process, indeed, but, as a matter of fact, the manufacture of Portland Cement is so complicated that it demands the constant vigilance of practically the entire mill organization to produce a material suitable for all kinds of cement work and to continue to do so indefinitely. It is essential that the raw materials run uniformly; that they must be finely ground and intimately mixed before burning; the mixture must be of the correct chemical and physical composition; the burning must be conducted at the proper temperature and the product of the burning must be ground to extreme fineness, and inasmuch as this embraces the entire process, the reason for the ever-watchfulness on the part of the operatives, is obvious.

Just as the advent of improved machinery increased the production, so did the quality of the product improve, with years of constant effort in its manufacture, culminating in “CHICAGO AA”  Portland Cement, “The Best that can be Made.”

The popularity of “CHICAGO AA” Portland Cement today is in itself sufficiently convincing that the pioneers of the company were correct in their belief that they had selected the best available site in the country for the manufacture of Portland Cement. Aided in their selection by years of experience in operating the old mill at Hawthorne, Illinois, many deposits of cement materials in various parts of the county were carefully investigated, but none of these were found to possess the same high-grade material. The importance of having at all times an adequate supply of fuel was also a strong factor in favor of the present site; the supply of good coal right on the property is almost unlimited. Chicago, and the populous districts surrounding it, located somewhat less than 100 miles distant, provided an important market and an ideal source of supply for labor, while the shipping facilities were at that time at least ample to take care of the output.

Located at Oglesby, La Salle County, Illinois, the property of the company, comprising upwards of 2,000 acres, is rich in cement materials of a very uniform character, and at the present rate of consumption will amply provide for our requirements for the next three centuries. This property was acquired in the year 1898, shortly after the conflagration at the old mill, equipped with machinery capable of producing a few hundred thousand barrel annually.

Following is an extract from Bulletin 243, Department of The Interior, United States Geological Survey, showing the analyses of the raw materials used in the manufacture of “CHICAGO AA”  Portland Cement:      The Pennsylvania (“Coal Measures”) rocks of Illinois cover most of the State south of a line drawn through Paxton, Wilmington, La Salle, Princeton and Rock Island. The greater part of this thick series of Coal Measure rocks consists of shales and sandstones, but the presence of occasional relatively thin beds of limestone is of interest.

One thick bed, or series of beds, is well exposed near La Salle and Oglesby.

The Chicago Portland Cement Company plant is located at Oglesby, La Sale County. The following section is exposed in their quarry, from above downward:

Limestones………………………...28 feet
Black slaty shale…………………...6 feet
Coal………….………………..….3 inches
Harder gray shale…………………..9 feet

The raw material used at the plant are limestone from this quarry and shale from both of the beds noted. Analyses of the raw materials are given in the following table, that of the shale being from the six foot bed of black shale:

            LIMESTONE    SHALE    
Silica (SiO )        6.06        53.12  Alumina (Al O )         }3.92        20.60
Iron Oxide (Fe O )    }        4.09
Lime (CaO)        49.46        4.02
Magnesia (MgO)        .91        2.24
Sulphur Trioxide (SO )    .10        n.d.
Carbon Dioxide (CO )    }39.06        }13.70
Water            }        }

The analyses of the raw materials as shown above have varied little if any since operations were first started on the property; in other words, we have as a natural advantage raw materials which are “uniform in character,” probably the most essential element in the manufacture of Portland Cement, hence the popularity of the phrase in advertising the product. Uniformity of the raw materials simplifies the mixing and proportioning of them to obtain a mixture of absolutely correct composition.

The excavation of the raw materials is the initial step in the process of manufacture. It will be        observed that the deposits are opened up on the side of a hill approximately three-fourths of a mile long, and almost horizontal in the workings, thereby greatly facilitating the removal of the materials.

A thirty-ton Vulcan traction shovel is used in excavating and loading the soil into cars (ill. 1) which run on temporary tracks laid close to the face of the quarry.  The soil is removed at the rate of 600 yards per day in summer, and is conveyed in cars to either end of the quarry-face and dumped ninety feet into the valley below.

Illustration 2 shows the churn drills at work on the rock ledge preliminary to blasting. After drilling, the holes are loaded with special dynamite cartridges sufficiently heavy to shatter the ledge without overthrowing or casting it out.

After blasting, the rock is picked up by steam shovels (ills. 3 and 4), loaded into cars (ill. 5), which are then attached to locomotives and hauled to a Fairbanks Standard Track Scale. Each car is weighed separately, and the proper proportion of shale added.

[The above article is from a booklet published by the Chicago Portland Cement Company in 1911. It will be continued in future issues of Natural News.]

Above a Chicago Portland Cement Company advertisement in the October 1908 issue of Cement World.  C.H.H.S. Collection.