By Dusty Fraley
In the early part of the 20th century, the demand for Portland cement was growing. The bulk of U.S. cement production was in the Northeast, and in the Southern states there were only seven cement plants. The need for cement in the South was more than twice what the production was. The time seemed right to build a cement plant in Chattanooga.
In August 1920, the Signal Mountain Cement Co. was established. The board of directors consisted of prominent local businessmen, including bankers Charles Lyerly and W.A. Sadd, and W.E. Brock of the Brock Candy Co. The initial capital investment was $3 million. The first public offering of stock was on Sept. 23, 1920, and consisted of 30,000 shares at $100 a share. The original prospectus indicates dividends were to be at 8 percent annually and the plant would be paid off in five years with substantial profit to be made in addition to the dividend. The investment in Signal Mountain stock was highly promoted by the Industrial Board of Chattanooga Chamber of Commerce.
A year later, a reorganization of the company and the board of directors brought in an experienced cement man to run the company. John L. Senior, who was associated with cement plants in Michigan and Texas, became president. Construction of the plant began in early 1922 in the area now known as Glendale. The location was considered particularly advantageous. There was a mile of waterfront along the Tennessee River, and the limestone and clay needed for production were located on the plant site. Coal, which represented 38 percent of the cost of cement, was found on Signal and Raccoon mountains.
The limestone was taken from an underground quarry on the west side of the property. Directly above the underground quarry, a streetcar line ran from Chattanooga up Signal Mountain. The rock was loaded into dump cars that ran on rails to the crushing department, where a crusher and two hammer mills crushed the stone down to a half-inch in size. The clay, also located on the plant site, was loaded into dump cars and transported by rail to the raw material storage area. The stone and clay were conveyed into four “compartment ball mills” which mixed the materials with water. The mills ground the raw materials so 90 percent of it would sift through a sieve. This product was called slurry.
Three kilns were located to take advantage of the terrain. The “slurry feed” came in at a higher elevation, and the burned material, clinker, discharged into a clinker cooler at a lower elevation. Then the cooled clinker discharged into the storage area at a still lower elevation. The clinker was ground with approximately 3 percent gypsum, at the finish grind department. The original finished cement storage consisted of six concrete silo-type bins holding approximately 15,000 barrels each.
It was the most modern of cement plants on Oct. 12, 1923, when the first clinker was produced at Signal Mountain Cement. Few changes were made in the plant over the next 30 years. Six additional cement storage silos were soon added. A grinding mill was added to “pre-grind” the stone and clay before it entered the raw mills in 1940. In early 1947, General Portland Cement Co., a firm that owned plants in Texas and Florida, purchased the plant, and it became a division of that company. Ties to the Chattanooga area remained strong, with local businessmen serving on the board of directors of General Portland.
In the 1950s a major change in the operations at the plant was required. The closest source of limestone was down river at Bennett’s Lake, close to Jasper, Tenn. Despite the fact the limestone would have to barged 30 river miles, General Portland leased approximately 400 acres of property and developed a new quarry. Barge-loading facilities were built at the quarry site, and barge-unloading facilities were built at the Chattanooga location.
Also, in the 1950s a new kiln was added. This kiln, 11 feet, 3 inches in diameter and 425 feet long, could produce as much clinker as two of the smaller original kilns. In the mid-1960s the plant installed two new mills for the grinding of the clinker into finished cement. With increased production, it was necessary to build additional silos to store the cement. These new silos were the first to incorporate loading facilities for bulk truck shipments.
In the early 1970s, air pollution problems at Signal Mountain Cement made front-page news. Cited by the Chattanooga-Hamilton County Air Pollution Board in 1970 for odor and particulate violations, the company began to take action toward cleaning the air. New electrostatic precipitators (dust removal systems) were installed on the two new kilns. By the late 1970s, the company had spent $3 million on air pollution control and $1.5 million on water pollution control. Despite this progress, controls continued to tighten and conflicts with the bureau continued. Rumors of the plant closing were hot topics of conversation by plant employees. The company’s supply of clay had run out, and slate, purchased from local sources, was being used as a raw material. To make matters worse, construction was down, causing decreased profits and temporary layoffs.
In the fall of 1981, General Portland was purchased by a Canadian firm, LaFarge. LaFarge already owned a plant in Alabama, which served the Atlanta market, and the Federal Trade Commission had them agree to sell to the Signal Mountain Division. In August 1982, a group of Italian investors purchased Signal Mountain Cement.
The new owners made few changes in the plant operations in the first 15 years of ownership. New pollution control equipment was installed, and a belt line to replace the truck haul of limestone was added.
On Oct. 12, 1998, Signal Mountain celebrated 75 years of production, and in the spring of that year, RC Cement, the holding company for Signal Mountain Cement, announced a major expansion. Today, Buzzi Unicem USA owns the plant on Suck Creek Road.
Dusty Fraley wrote this article as a student at Lookout Valley High School. It first appeared in Volume 2, No. 2 of the Chattanooga Regional Historical Journal. Both of his parents worked at the Signal Mountain Cement Co.