The Man that invented the Modern Cement Plant!

Thomas Alva Edison without doubt is the person that by-self has had the biggest influence in the shape of the modern cement production technology.

It is interesting that this episode in his vast productive inventor career, a development that had monumental consequences for all of construction in the twentieth century, went virtually unmentioned in the history of technology, or is slightly explained in Edison biographies. Is a lot about Edison’s relatively unsuccessful attempts to cast entire houses in a single mould. But there is little about how he successfully invented the integrated cement plant. 

Where this fantastic story starts?

In 1879 Edison begins his interest for mining during its searching for a cheap source of platinum for his electric lamp. He planned to extract platinum from gold mining tailings, as well as gold. It is clear that Edison had become fascinated by the processes of metal extraction from ores. He set up the Edison Ore Milling Company. Edison's key invention, was a separator that could concentrate metallic ores by means of electromagnets placed in a stream of falling fine-crushed rock or sand.

He equipped his new West Orange laboratory for the systematic investigation of ore processing, giving birth to two small plants. Finally a industrial size plant was build in New Jersey at Ogdensburg. Edison was happy in this full-scale testing environment and devoted focused to the perfection of the ore separation process, particularly the "giant rolls" rock crushers and the conveying machinery. (Edison Method)

In fact the lasting legacy of the Ogden plant was the production engineering "know how" it generated: the systems of high-volume material handling, power supply, measurement and control at high speed and with minimum human intervention. These were clearly the aspects of the work that fascinated Edison and he devoted seven years of his life to them.

Each innovation challenged conventional practice, often in radical ways. No step of the process escaped careful evaluation, from the extraction of the ore by steam shovel to the disposal of high quality dry sand following ore separation (sold to cement manufacturers).

Unfortunately the Ogden Plant closure in 1897 because the price of high-grade dropped from $6.50 to $3.50 per ton, a price at which Ogden's ore concentrate briquettes could not compete more. Edison was decided to use all the knowledge developed in the Ogden plant in the cement industry. It is no coincidence that Edison was attracted to an industry that, like electricity, was doubling in scale in five years, twice the average rate for American industry of ten percent a year.

Edison Innovations that shaped the new cement plant !

In 1898 Edison bought land at Stewartsville, New Jersey, to be the site for his new venture. With his former ore expert Mallory he visited several cement plants in Pennsylvania, then the heart of American cement production. As he did for all his ventures he read everything he could find about cement manufacture, which was a lot at this time. (Edison Method)

1.- Automation and auxiliary services distribution.- Mallory suggested they should contract engineers to design the cement plant, but Edison said he will do it. They went to a drafting table where Edison completed a detailed plan of the entire plant in 24 hours! Served by broad gauge rail direct from the quarry, the plant was designed to automatically process materials. Key to the design was a two level tunnel running beneath the length of the works carrying steam, water, pneumatic air, electrical and communications cables, as well centralized lubrication system.

2.- Centralized Lubrication System.- Edison was particularly concerned with oil waste in lubrication as well as dirt contamination, he designed a lubrication system that employed just two employees to maintain 10,000 bearings, using filtered and re-circulated oil.

3.- Giant Crushing.- The giant rolls adapted from the Ogden plant could crush individual rocks of up to eight tons in contrast to crushers at conventional plants that could accept only pieces of rock small enough to be lifted by one man.

4.- Accurate Quality Control system.- Weighing and batching of rock into the crushers was electrically controlled to avoid human error. Around 1900, Edison arrived to the conclusion that cement quality depends on; 1) the proportion of the raw materials and their calcination in the kiln, and 2) the fine grinding of the clinker. Edison aimed to have a high precision to processes that were in that moment still so empiric, he saw this as a necessity for a real industrialization of the industry.

For example: The proportion of raw materials was made by barrow or load units, and may be more or less accurate. Rule of thumbs was never accepted by Edison, and he made a system of weighing each material. The system consists in two hoppers suspended above two scales whose beams are electrical connected with a hopper closing gate. The scales are set according with the chemist orders.

5.- Packing Plant.- Edison even designed in great detail the packing station that fed cement into bags or barrels at the end of the process. After 10 years of built still was taken as reference of modern and efficient packing system

6.- Long Kiln.- The conventional coal fired rotary kiln use to have a dimension of 60 foot long with 6 foot diameter, and the biggest kilns at that time produced 200 Barrels/day. In 1900 Edison designed a new type of kiln that was 120 foot long and 6 foot in diameter, made up of 10 foot lengths of cast iron tube bolted together. The kiln was supported and revolved on 15 bearings, and was to use 2 high- pressure powdered coal guns to inject fuel and air into the kiln, maximizing the flame size for a efficient calcination.

Edison had a ten foot long model kiln built and studied it carefully through a series of experiments before ordering a full size kiln for the plant. He also had a one sixth scale wooden model of the whole works built, to refine materials handling ideas and automation to a maximum extent (Edison Method)

It took 3 years of intensive experimentation to reach the target of 1,000 barrels a day. Despite the great skepticism of the established cement producers who had predicted its failure, once they became aware of Edison long kiln success they began to copy him. In 1906 there were 57 kilns 125 feet or longer, and by 1910 half of the cement produced in America came from Edison type kilns.

7.- Higher Cement grinding finest.- Edison insisted on the fine-grinding of cement, based on German research and much strength testing of samples, was initially not accepted by American manufacturers who were happy to grind to a lower standard, because their Portland cement was already much stronger than the native natural cement. In reply to Mr. Matcham of the Lehigh Portland Cement Company who had written to him questioning the need for fine-grinding, Edison replied "The finer you grind, the better the Cement and the harder that it will be ". The grinding of cement was increased from 75% to 85% pass the 200 Mesh, against all the rest of the industry that believed that this was not necessary. 

8.- New uses of cement and concrete .- The Edison Portland Cement Company became USA largest cement producer. His innovative redesign of the rotatory kilns increased efficiency so much that led the industry to overproduction, lowering the cement prize. For this reason Edison joined the Portland Cement Association (PCA) to promote the use of concrete. Despite the slowdown cement use during the WWI, in general continued to grow with the general adoption of concrete construction, concrete products and highways and by 1924 the industry produced 146 million barrels of cement, (25 million tons.).

The licenses for the Kiln and Giant crushers paid to him a penny per barrel for all cement made in USA until 1930.

Edison: The "Inventor Philosopher"

Still passionate about the virtues of concrete construction, his cement house for working-class families remains the most visible of his experiments. In 1907 designed a method of casting houses in a single operation of twelve hours using iron molds. Although he clearly had an eye to cement sales he explicitly declared his venture to be licence free.

Edison's early experiments using wooden molds were disappointing. After radical re-design and simplification new molds were made and two houses were successfully cast at South Orange, New Jersey. Later, in 1917, Edison was able to build a development of about a hundred houses for industrialist Charles Ingersoll, in New Jersey, but after that no more houses were built, due the great investment required and the not acceptation of the customers that preferred more traditional methods.

Thomas Alva Edison well deserves to be named: "the father of the modern cement Plant"

Wood will rot, stone will chip and crumble, bricks disintegrate, but a cement and iron structure is apparently indestructible. Look at some of the old Roman baths. They area as solid as when they were built”

Thomas Alva Edison

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Luis Fuentes