Limestone is a sedimentary rock which is often composed of the skeletal fragments of marine organisms such as coral, foraminifera and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). About 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock. Limestone has numerous uses: as a building material, an essential component of concrete (Portland cement), as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, as a chemical feedstock for the production of lime, as a soil conditioner, or as a popular decorative addition to rock gardens. To make Portland Cementâ??the most common type of Cementâ??powdered Limestone is heated in a rotary kiln. As a source of calcium, it joins with powdered clay to produce a product called clinker, which is then ground with a source of sulfate, like gypsum. It is mixed with water, sand and crushed rock to create concrete.
Limestone.
Fly ash, limestone, gypsum, clinker, GGBFS, GBFS furnace slag, aggregates.Import and exports
Fish Meal , Limestone, Gypsum, Cement. Bitumen. Salt. Marble Chips. Aggregate. Clinker. Soda Ash..
Chrome ore, iron ore, limestone, soap stone, gypsum, rock salt, sulphur lump.
Barium sulfate, calcium carbonate, silica (quartz) granules & power, fine talc, hydrated lime, quicklime, pink salt, bentonite, dolomite powder and chips and china clay.
Limestone, garnet, stone aggregate, furnace slag, sulphur, ammonium nitrate, urea, nano silica, micro silica, kaolin, clinker, fly ash, ggbfs, coal grit, quick lime, gypsum, silica sand, salt, potassium chloride, calcium chloride, molasses, barite, bentonite, ilmenite, zircon, magnesium oxide, petcoke, diesel..Commodity trading, import, and exports
Limestone, nylon mono netting and lines.Sourcing
Clinker consists of various calcium silicates including alite and belite. Tricalcium aluminate and calcium aluminoferrite are other common components. These components are often generated in situ by heating various clays and limestone. Portland cement clinker is made by heating a homogeneous mixture of raw materials in a rotary kiln at high temperature. The products of the chemical reaction aggregate together at their sintering temperature, about 1,450 C (2,640 F). Aluminum oxide and iron oxide are present only as a flux to reduce the sintering temperature and contribute little to the cement strength. For special cements, such as low heat (LH) and sulfate resistant (SR) types, it is necessary to limit the amount of tricalcium aluminate formed. The major raw material for the clinker-making is usually limestone mixed with a second material containing clay as source of alumino-silicate. Normally, an impure limestone which contains clay or silicon dioxide (SiO2) is used. The calcium carbonate (CaCO3) content of these limestones can be as low as 80%. Second raw materials (materials in the rawmix other than limestone) depend on the purity of the limestone. Some of the second raw materials used are: clay, shale, sand, iron ore, bauxite, fly ash and slag. The clinker surface and its reactions in different electrolytic solutions are investigated by scanning electron microscope and atomic force microscopy. Portland cement clinker is ground to a fine powder and used as the binder in many cement products. A little gypsum is sometimes added. It may also be combined with other active ingredients or chemical admixtures to produce other types of cement including: ground granulated blast furnace slag cement.
A cement is a binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Cement is the most widely used material in existence and is only behind water as the planet's most-consumed resource. Cements used in construction are usually inorganic, often lime or calcium silicate based, and can be characterized as either hydraulic or non-hydraulic, depending on the ability of the cement to set in the presence of water (see hydraulic and non-hydraulic lime plaster). Non-hydraulic cement does not set in wet conditions or under water. Rather, it sets as it dries and reacts with carbon dioxide in the air. It is resistant to attack by chemicals after setting. Hydraulic cements (e.g., Portland cement) set and become adhesive due to a chemical reaction between the dry ingredients and water. The chemical reaction results in mineral hydrates that are not very water-soluble and so are quite durable in water and safe from chemical attack. This allows setting in wet conditions or under water and further protects the hardened material from chemical attack. The chemical process for hydraulic cement found by ancient Romans used volcanic ash (pozzolana) with added lime (calcium oxide). Portland cement is by far the most common type of cement in general use around the world. This cement is made by heating limestone (calcium carbonate) with other materials (such as clay) to 1450 �°C in a kiln, in a process known as calcination that liberates a molecule of carbon dioxide from the calcium carbonate to form calcium oxide, or quicklimeâ??which then chemically combines with the other materials in the mix to form calcium silicates and other cementitious compounds. The resulting hard substance, called 'clinker', is then ground with a small amount of gypsum into a powder to make ordinary Portland cement, the most commonly used type of cement (often referred to as OPC). Portland cement is a basic ingredient of concrete, mortar, and most non-specialty grout. The most common use for Portland cement is to make concrete. Concrete is a composite material made of aggregate (gravel and sand), cement, and water. As a construction material, concrete can be cast in almost any shape, and once it hardens, can be a structural (load bearing) element. Portland cement may be grey or white.
