Plant: Peerless Portland Cement, Union City, MI
The Peerless Portland Cement Co. plant here was organized in 1896 with capital of $250,000. Oldest of the recent cement plants following the Portland process, it first operated as a vertical kiln plant, was remodelled to the rotary kiln. Plant officers were from Alma, Battle Creek and Saginaw. It was a close corporation, with few stockholders.
The plant is located n Union City, and mined marl at Turtle Lake about three miles north of Union City. Six hundred and seventy-five acres of marl land are owned by the company, and is reached by means of a railroad off the Air Line division of the Michigan Central. The marl is found upon the surface, and is so dry that water has to be added when it reaches the plant. The marl is almost entirely free from organic matter and is very readily worked. By means of a bucket dredge, operated on a track, the marl is dug and lifted into the dump cart. To obtain the marl thus dry the level of Turtle Lake, "which had been twice lowered before, the last time in 1873," but still stood 22½ feet above the St. Joseph River, was lowered some 14 feet.
From the Detroit Journal of April 16, 1902, we cite the following account of the changes in the manufacturing plant: "Intermittent vertical kilns were first installed by the company. These kilns were charged, then lighted and burned out like a limekiln. From a distance of three miles the marl was first hauled to the plant in wagons, then it was mixed with clay in a pug mill and made into bricks. These bricks were first dried in a drying kiln, then piled in the burning kilns with alternate layers of coke. After being burned the clinkers were drawn off and ground. The process was necessarily slow, as compared with that in use the present day.
Two years ago another change was made in the mill and Dietch Continuous Vertical Kilns installed. In these kilns the mixture was charged at the top and the clinker drawn off at the bottom. Still progressing the company decided last fall to construct a modern cement mill and to that end hundreds of workmen have been engaged all winter in the erection of a model cement plant.
Many entirely new features have been introduced into this mill, and right from the start an output of 1,200 barrels per day is confidently expected from the eight 70-foot rotaries. Two hundred thousand dollars is being expended upon this plant. "Beds of both plastic and clay shale owned by the company are located within a mile of the mills. The shales belong to the Coldwater formation.
"The cars of marl are pulled up an elevated tramway on the track scales where the marl is weighed, and then the clay is added before being dumped into the stone separator. From there it goes to the pug mill and then into a large tank where through return pipes the mass is kept running continuously in order to obtain a uniform mixture. It is corrected at this point by the addition of the proper amount of clay or marl determined by the chemist. From these tanks the mixture is pumped into the wet grinding tube mills and then falls into great floor tanks of concrete. In the bottom of these tanks a continuous screw conveyor forces the slurry into mammoth concrete correction tanks.
These tanks are the source of just pride to the engineering force of the company. They are constructed entirely of concrete and are 22 feet deep 'by 22 feet wide and 22 feet long. The slurry in these tanks will be agitated by compressed air. The clay is prepared by being first dumped into a dryer and then ground in a Williams mill.
"The great rotary room is undoubtedly the most interesting part of the plant. Some innovations are here introduced that will materially increase the output of each rotary. The inventions are the product of advanced thought and the broadest of experiments. The rotaries are seventy feet long, being ten feet longer than the largest rotaries in any Michigan mill. The pulverized coal, to feed the rotaries, is prepared in a separate building where the most improved coal grinding machinery has been erected. The Peerless company has placed devices on the rotaries from which the waste heat from the kilns is utilized in drying the slurry before it enters the kilns. This is automatic and is said to increase the capacity of each kiln to a marked degree.
The rotary room was constructed on a side hill and this has proven especially advantageous, as it saves the handling of the clinker as it leaves the kilns. Under the clinker end of the kilns has been constructed a retaining wall and in this room, 21 feet below the kilns, are the foundations for the eight automatic Wentz clinker coolers, which are being erected so that the hot clinker falls directly into them. By this device the hot air is fanned off of the clinker and driven back to aid in reducing more slurry to a calcined state. "As the clinker drops from the coolers it is conveyed along the floor to the rolls and from there into eight Griffin mills and then into two large tube mills for the finishing process.
As the cement leaves these mills it is elevated by belt and tripper arrangement to the top of the three-story warehouse and there dumped into hopper bins. These bins are two stories in height and are constructed of the best Kentucky oak, the huge pillars not depending upon the walls of the building, the construction being entirely within itself. As the cement drops from the third to the second story bins it is turned over and from there goes to the packer.
The old and the new warehouses, which extend along the Michigan Central tracks, have a capacity of 100,000 barrels. It will be seen that the company is amply provided, for winter storage. At the track, coal can be unloaded and elevated to the boiler room of the plant.
"The power plant promises to be one of the finest in the state. Four Scotch Marine internally fired boilers will furnish steam for driving a 500 horse-power Hamilton Corliss engine, a Fitchburg Tandem Compound 450 horse-power, and a 300 horse-power simple engine. Rope drives will be used in part of the plant. Twenty electric motors are being installed and electrical transmission used to advantage in driving the gear of many of the machines.” [GSM-1903]