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The successful commercialization of the rotary kiln, at Coplay, by Jose De Navarro played a critical role in these changes. It is important to note that the rotary kiln was an English invention, with the first patent being awarded there in 1877. An improved version of the rotary kiln had been patented in England in 1885 by Ransomes but still had not been successfully commercialized. It is also important to note that the first attempts to apply the rotary kiln were not made in the Lehigh Valley, taking place in Oregon and New York. But all of these attempts failed, either technically or commercially.
Jose De Navarro was an entrepreneur with a particular interest in construction. He was involved in building the Elevated Railway and Central Park Apartments in New York City. These experiences interested him in cement and, in particular, production using a rotary kiln. After some costly unsuccessful experiments at Kingston NY, because Portland cement was being manufactured successfully at Coplay, he formed a company and leased land near the Coplay Cement Co., on the site of a former natural cement manufacturer. Though production of Portland cement using a Ransome-style rotary kiln began from November 1889, it took some time to achieve both technical and financial success. De Navarro's original company failed but a new company, the Atlas Portland Cement Company, with the involvement of the president of the large New Jersey Central railroad, took over. By 1896, a story in the Wall Street Journal describes the company as finding "a market for all it can produce". The success of the firm is also demonstrated by its building a much larger plant at Northampton, just behind Siegfried, and then rapidly expanding this plant. In 1901, the Atlas Portland Cement Co. was the largest cement company in the United States – more than twice the size and probably five to ten times the size of most firms in the industry. This continued for some time, with the Atlas Portland Cement Co. providing cement for the Panama Canal, among other large projects.
Cement production in a rotary kiln occurs as follows. Raw materials are quarried, crushed and fed into a kiln which is a revolving iron tube. As the material enters and progresses down the tube it is cooked with a flame from a jet of fuel oil into clinker. The clinker is quickly cooled and mixed with gypsum before grinding into Portland cement.
Producing with a rotary kiln has two advantages over vertical kilns. First, the quality is higher and more uniform due to more rapid heating and cooling and a more uniform application of heat to the raw materials. Second, production costs are lower as mechanization eliminates most of the labor required for processing raw materials.
