The production of Portland cement makes up approximately 90% of the total cement produced in the U.S. The main raw materials categories used to make Portland cement are lime, silica, alumina, and iron, but the process also consists of byproducts from other industries such as power plant fly ash, steel mill scale, and metal smelting slag.
STEP ONE – RAW MILL
In the first stage of cement production, the raw materials are blended to meet the desired chemical composition and then ground to the optimum size for pyroprocessing. After milling, the material is moved to storage silos or slurry tanks until pyroprocessing.
In this stage, a pulse jet dust collector and cartridge is needed for the milling process as well as material handling, conveying, and storage processes.
STEP TWO – COAL GRINDING
Most cement plants today use coal as fuel for the pyroprocessing stage. The coal is ground to the required fineness based on the volatiles in the coal to ensure the most efficient combustion is achieved.
There are multiple stages of the coal processing area, including coal handling, initial crushing, conveying, final grinding, and storage. All of these areas benefit from the presence of air pollution control equipment, especially explosion-proof equipment.
STEP THREE – PYROPROCESSING/KILN
The blended and ground raw materials (known as “Raw meal”) are not fed to the pyroprocessing system (a rotary kiln) where they are subject to extreme temperatures up to 2,700° F. This high temperature causes chemical reactions that convert the raw meal to clinker. Clinker nodules range in size from 1/8” to 2”.
A pulse jet air dust collector is appropriate for this stage of the process.
STEP FOUR – CLINKER COOLER
The clinker cooler cools the clinker exiting the kiln from 2,000° F down to 250° F. This is required to achieve the desired chemical qualities of the product and enables the use of conventional conveying equipment to handle the product in the following stages of production.
A portion of the heat is recovered during the cooling process and the resulting balance of air is vented to the atmosphere and must be filtered to an acceptable emissions level. A pulse jet dust collector is helpful to have during this stage of the process.
STEP FIVE – FINISHING MILL
In the finish mill department, the cooled clinker is ground to a fine powder using ball or tube mills. Additives called grinding aids are also introduced during this stage to help facilitate the milling process and to import specific properties to the cement.
Note that the type of grinding aid utilized can significantly impact the performance of fabric filters used in a dust collector. As with other stages, a pulse jet dust collector can assist in managing emissions.
STEP SIX – MATERIAL HANDLING; CONVEYING; LOAD OUT
These steps are not so much processes as they are various emissions points requiring dust collection. Sly offers extensive expertise in material handling, storage silos, conveying, and load out.
For information about air pollution control equipment designed to manage emissions during production processes, call Sly at 800-721-3545 and one of our experienced representatives will tailor a custom solution designed for your business.