Introduction

Cement has been manufactured at the Hannibal location since 1903. Several thousand men were needed for construction and operation of the original plant. A large number of Polish, Slavic, Hungarian, and Italian immigrants were attracted to jobs here. They settled on plant property and formed the small community of ILASCO, named for the constituents necessary in the cement-making process: Iron, Limestone, Aluminum, Silica, Coal, and Oxygen.

Our product has long been recognized for its consistent quality and was selected for many notable construction projects, including the Empire State Building and the Panama Canal.

The original plant was expanded and improved throughout its operating history until 1966, when a new manufacturing facility was constructed to replace it. At that time, one 622′ x 16′ kiln replaced sixteen small kilns and production was more than doubled. This kiln was the second longest cement kiln in the world, with annual production rates of over 600,000 tons of clinker.

Improvements in the technology and efficiency of the cement manufacturing process, along with increasing age on the existing plant, prompted the construction of a new plant in 2006. The current plant is now the third plant to produce cement from the same location south of Hannibal. This latest modernization included more than just a new cement kiln.

Modernization began in the quarry with replacement of the existing fleet of 50 ton haul trucks with 70 ton Komatsu units, including larger Komatsu front-end loaders, and a new impact crusher that doubles the rock crushing capacity. The on-site quarry provides both limestone and shale, which constitute 92% of cement raw materials. All raw materials are crushed and conveyed to a single new rock storage building, where the segregated raw materials are stockpiled for blending. A raw material reclaim system, consisting of a tunnel, belt conveyor, and individual apron feeders controlled by a cross-belt analyzer, blend the five- component raw material mix. The blended material is stored in a day bin just ahead of a new in-line vertical roller mill, where all the raw materials are dried utilizing pre-heater off gases and ground to a fineness up to 85% passing 90 microns.

The vertical roller mill is a Loesche Type LM45.4 four-roll mill equipped with a dynamic classifier and a rock circulating system. The mill capacity is rated at 275 short tons per hour. The mill product is then conveyed to a 6,000 ton capacity, concrete slipped-formed, homogenizing silo equipped with an Ibau Hamburg blending and withdrawal system.

The new pyro-processing line was supplied by KHD Humboldt Wedag and consists of a four-stage pre-heater / flash calciner with PYROTOP technology followed by a 171’ long by 14.5’diameter kiln. The newest technology Pyrofloor PFC 533A clinker cooler featuring an inlet static section, four movable cooling tracks and a roll crusher at the cooler outlet cools the clinker material down to a temperature safe for handling and storage. The total aerated surface in the clinker cooler is 686 ft2. The rated system clinker production capacity is 3,000 stpd or greater with a power consumption at 10.8 kWh/st or less.

Cement production capacity was also increased by the addition of a KHD supplied RP 13-140/140 roll press, complete with a VSK80/18-2500 separator. The roll press circuit was coupled to one of two existing 3,000 HP finish mill circuits, each of which produce 62 stph. The roll press modification boosted total mill circuit output to 130 stph, and total cement production capacity to 190 stpd.

Additional infrastructure support modifications were also made. These included incorporating waste fuels for the new plant, converting existing raw material storage silos into clinker storage, increasing cement storage and load-out capabilities at the plant as well as at the St. Louis, MO distribution terminal. Continental’s distribution network includes shipments from the production facility and terminals in St. Louis, Missouri and Bettendorf, Iowa.

In order to respond to an environmentally beneficial opportunity and remain competitive, Continental began using supplemental waste fuels for energy recovery as a direct replacement for coal in 1986. This usage increased over the next few years and, in 1992, Continental acquired the assets of an on-site fuels recycler and formed MFR (Missouri Fuel Recycler). MFR rapidly expanded the use of waste fuels by adding two patented processes for handling solid waste. In 2005, Continental/MFR partnered with AES to form Green America Recycling. Today, Continental/GAR is recognized as an industry leader. This merger of operations has provided a new era of competitive cement operations and has proven to be environmentally beneficial. By replacing coal, a natural resource is preserved, and kiln stack emissions are much cleaner. Waste that would otherwise be incinerated is reused for energy and we all benefit.

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How Cement is made at Continental

Cement is made from common materials such as limestone, clay, silica, and iron ore. Principle raw materials are a blend of 88% limestone, 6% shale, with the remaining raw materials being clay and iron ore.

The limestone and shale are mined from quarries on Continental’s +/-3,500 acre plant site at Hannibal.

Clay is trucked in from reserves at our Owensville, MO operation, 120 miles southwest of the plant. Large limestone boulders are dumped into the primary crusher and broken into gravel sized particles. Clay is also introduced through the crusher.

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Portland Cement from Clinker

Clinker is discharged from the kiln into a cooler, where high volume/high pressure fans drive the heat from the material. Heated air is recycled back into the manufacturing process.

After the clinker cools to approximately 150°F, it is delivered by a conveyor system to storage silos.

Clinker is then fed to the finish mills with about 5% gypsum to produce Portland cement. The combined finish mill capacity is approximately 190 tons of cement per hour.

After leaving the finish mills, the finely ground cement is transported to the storage.

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Environmental Controls

The nerve center of the plant is the central control room where monitors and instrumentation allow operators to continuously control the entire manufacturing process. Redundant certified Continuous Emission Monitors (CEMs), installed on the kiln stack, provide a record of O2, CO, CO2, NOx, SO2, THC, and opacity. Automatic waste feed cut-offs, set by stack testing results and federal regulations are in place to assure compliance. A cement kiln provides a perfect environment for safely processing certain waste materials and recovering their energy value. The intense heat of the process ensures destruction of any organics in the fuel, with residual metals chemically bonded.