Portland concrete, the basic ingredient of concrete, is a closely controlled chemical combination of calcium, silicon, aluminum, iron and small amounts of other ingredients to which gypsum is added in the final grinding process to regulate the setting time of the concrete. Lime and silica make up about 85% of the mass. Common among the materials used in its manufacture are limestone, shells, and chalk or marl combined with shale, clay, slate or blast furnace slag, silica sand, and iron ore.
1. Raw Material Preparation.
Mining of limestone (or sand, shale, clay, and iron ore) requires the use of drilling and blasting techniques. The blasting techniques use the latest technology to insure vibration, dust, and noise emissions are kept at a minimum. Blasting produces materials in a wide range of sizes from approximately 1.5 meters in diameter to small particles less than a few millimeters in diameter. Material is loaded at the blasting face into trucks for transportation to the crushing plant. Through a series of crushers, such as jaw crusher, cone crusher, impact crusher, mobile crusher, and screens, which both supplied by our company, the limestone is reduced to a size less than 100 mm and stored until required.
2. Raw Grinding (wet process and dry process).
4. Finish Grinding and Distribution
The black, nodular clinker is stored on site in silos or clinker domes until needed for concrete production. Clinker, gypsum, and other process additions are ground together in grinding mill, such as ball mills, vertical mills, to form the final concrete products. Fineness of the final products, amount of gypsum added, and the amount of process additions added are all varied to develop a desired performance in each of the final concrete products.