Cement Industry Methods
There are three ways to find the optimal chemical compound for cement.
Wet way
The raw materials are selected and mixed with water to give a suspended output. Clinker is formed at (1480) ° C. This process depends on:
Cracking and mixing of raw materials
Raw materials of limestone, silicate, mud and surface dust are broken by crushers, then dissolved and transported, to be stored as piles in open areas or covered.
Milling
Raw materials are transported in suspensions mills, where they are mixed with water and grinding suspensions continue until they reach the desired smoothness.Then the suspensions are then transferred to storage silos, where they become homogeneous after the final adjustment of its components, and samples are taken periodically to ensure that its fittings conform to specifications. Hanging basins, where mills turn it into a homogeneous mixture.
Oven and radiator
Pull the suspension from the bottom of the sink to the feed hole of the rotary kiln (long cylindrical kiln), lined from the inside with a thermal brick, and rotates slowly inclined slightly from the horizontal plane. This tilt allows the furnace contents to be pushed forward while turning. At the front (bottom) end of the furnace, high-temperature combustion gases flow to the top (rear) of the furnace in the current opposite to the movement of the furnace contents pushed down, and the clinker is cooled by an air cooler. The length of the furnaces in the wet method is longer than the dry method, so that it completes the process of drying the paste mixed with huge metal chains inside the oven.
Final milling and packing
The clinker is transported to the core mills, where gypsum is added and milled, then packed in bags.
Dry way
The use of dry processes for the cement industry has been spreading to gradually replace wet processes, due to the abundance of energy characteristic of dry processes, the precision of control processes and the mixing of raw materials, without adding water. The main operations in this way are:
Cracking and mixing of raw materials
Raw materials of limestone, silicate, mud and surface dust are broken by crushers, then dissolved and transported, to be stored in piles in open or covered areas.
Milling
Raw materials are introduced into a rotary dryer (in case of humidity exceeding a certain percentage), they are dried by hot air or exhaust resulting from the operation of the furnace, then the raw materials are ground in the raw material mills and transferred to pre-mixing silos, where they become homogeneous by The process of compacting and pulling, then the homogeneous raw materials are transferred from storage silos or other types of pre-mixing storage to mixing places. The mixing process is carried out by 30% clay, and 70% limestone.
Oven and radiator
Homogeneous raw materials are drawn from the bottom of the storage silo to the feed slot of the multi-stage primary heating tower, and the tower height may reach 120 m. Natural gas or diesel is used as a thermal energy source, and hot air from clinker cooling is used as an additional source of heat. The furnace tilts slightly on the horizontal plane to allow slow movement of solids downward. The combustion gases move upward in the current opposite to the movement of solids. Hot combustion gases heat the raw material, at the furnace feed hole, and provide calcium carbonate.
Final milling and packing
The clinker is transported to core mills where gypsum is added and packed in bags.
Semi-dry method
The semi-dry method is a special case of dry processes, where the furnace (Lippolin Kellen) or column furnace is used. Of water.
Cement Chemistry
To indicate phases, we usually use abbreviated references, symbolized by b
These are: Fe2O3) F, (Al2O3) A, (Sio2) S (chaux) Cao C) The ingredients we encounter in the cement industry, we mention them.
(C3S): (CaO) 3 (SiO2)
Aluminate: (C3A): (CaO) 3 (Al2O3)
Bulit: C2S): (CaO) 2 (SiO2)
Lime: (CaCO3)
Slate: .Célite still named Slate C4AF.
Lime: usually less than 2% of clinker mass
Foggett: Sometimes (C4AF): (CaO) 4 (Al2O3) (Fe2O) Aluminofogit or Pegonmeligit (CaO) 2FeAlO3) This is half a composition.
Gibbs: (CaSO4). (H20) Heated at (60-200) ° C
Bigclass: MgO
Bogtlundit: contributes to the hydrogenation of free lime. (Ca (OH) calcium hydroxide
Sand: Silice (SiO2)
The chemical composition of cement (the aforementioned materials helps cement hardness and tighten it for months
Final quality estimated by values calculated from the composition.
