Such lime has the optimum properties of high reactivity, high surface area and low bulk density. They are i) rotary kilns and ii) vertical kilns. The structure of the kiln is either vertical cylinder or rectangular shaft with refractory lining. Rotary kilns also need limestone with good tumbling index. Some of these kilns are described below. This temperature is usually defined as the temperature at which the standard Gibbs free energy for a particular calcination reaction is equal to zero. Radiation and convection losses are highly relative to other designs of lime kilns which result in generally higher energy consumption compared to other types of kilns. The combustion air injection is at the top (main) and lances (10 %). As the temperature rises, the surface of the limestone shrinks and closes the pores created by the escape of CO2. Limestone properties, such as strength before and after burning, type of available fuel and product quality, are to be considered when choosing a kiln technique. 1. This type of limestone become so dense during calcination that it prevents the escape of CO2 and become non porous. Most of the kilns used are based on either the shaft or the rotary design. The combustion air is preheated by surplus heat in the exhaust gases and/or by using it to cool the lime. cines v. tr. Rotary kilns can be long kilns with straight rotary coolers while verticals kilns can be several types. They are generally used for horizontal or inclined transfer. The kiln can burn gaseous, liquid or pulverized fuels and is reported to produce a soft burned lime with a residual CaCO3 content of less than 2.3 %. Industrial & Engineering Chemistry Research 2013 , 52 (21) , 7002-7013. Annular shaft kilns (ASK) – The major feature of ASKs (Fig 5) is a central cylinder which restricts the width of the annulus, and together with arches for combustion gas distribution ensures good heat distribution. PRKs (Fig 2) are generally considerably shorter than the conventional LRKs (e.g. The decrease of reactivity is accompanied by a reduction of the surface and the porosity of the lime, which is called sintering. Hence, the plant consists of stationary equipment and a few moving components (Fig 6). The chemical composition can also vary greatly from region to region as well as between different deposits in the same region. three step process: stone preparation, calcination, and hydration. In some cases, calcination of a metal results in oxidation of the metal. A feature of the kiln is that the temperature of the lower combustion chambers can be varied to control the reactivity of the lime over a wide range. Calcination of Limestone Calcination or calcining is a thermal treatment process to bring about a thermal decomposition. The generation of sufficiently active CaO from the raw meals entering the cement plant for the CO 2 capture requires calcination of these materials at around 900 °C in various atmospheres of CO 2. Calcining zone – Fuel is burned in preheated air from the cooling zone and (depending on the design) in additional ‘combustion’ air added with the fuel. Soft burnt lime is produced when the reaction front reaches the core of the charged limestone and converts all carbonate present to lime. A typical example is the manufacture of lime from limestone. Calcination, the heating of solids to a high temperature for the purpose of removing volatile substances, oxidizing a portion of mass, or rendering them friable. The kiln can be fired with solid, liquid and gaseous fuels or a mixture of different types of fuels. The disadvantages include formation of rings (coal ashes, calcium sulphates, clay), and pre-heater is an additional piece of equipment to maintain. Very low residual CO2 is achievable. The test method to measure the reactivity of ground lime is carried out by slaking the lime in water. In the calcining process, the partially burnt limestone will be burnt thoroughly. The arches serve the same purpose as in the double-inclined kiln. Calcination, therefore, is sometimes considered a process of purification. Then we get the byproduct that is quick lime i.e (CaO) and carbon dioxide i.e (Co2) is released in the air. Travelling grate kilns – For limestone feed with a size range of 15 mm to 45 mm, an option is the ‘travelling grate’ or CID kiln. Type of fuel can be gas, liquid, pulverized solid fossil fuels, waste fuels, or biomass. They operate more successfully when there is a slight downward slope from the feed to the discharge point. There is high retention of S from fuel in the lime. It consists of four or six alternately inclined sections in the calcining zone, and opposite of each is an offset arch. Of the variables studied, the limestone feed rate has the strongest effect on the temperature and calcination fields, whereas inclination angle and rotational speed are relatively less important. Typically, limestone contains more than 90 % CaCO3 (calcium carbonate) and a few % MgCO3 (magnesium carbonate). Limestone is a naturally occurring mineral. Mixed feed shaft kiln (MFSK) – MFSK (Fig 3) uses limestone with a top size in the range of 20 mm to 200 mm and a size ratio of around 2:1. ... INDUSTRIAL EVALUATION OF SAKASAR LIMESTONE EXPOSED IN WESTERN SALT RANGE, PAKISTAN. The combustion air consists of cooling air injected from the bottom. The reactivity of produced lime is high with reasonable flexibility of reactivity from high to medium, when the limestone allows. There is fuel flexibility since PRKs can use gas, liquid, or pulverized solid fossil fuels as well as waste fuels and biomass. Lime is also used in different quantities in the sintering process for the preparation of iron ore, in the desulphurization of pig iron, for acid neutralization, and in water treatment facilities. This product is known as dead burnt or low reactive lime. Low value of decrepitation decreases the porosity of the bed thus impeding the flow of the gases the kiln efficiency. Because of the fact that process conditions can be easily and quickly varied, LRKs can produce a wider range of lime reactivity and lower residual CO2 levels than shaft kilns. Jean Rey noted that lead and tin when calcinated gained weight, presumably as they were being oxidized. A high productive product is relatively soft, contains small lime crystallites and has open porous structure with an easily assessable interior. Whereas shaft kilns usually incorporate a preheating zone, some other lime kilns, namely rotary kilns, sometimes operate in connection with separate pre-heaters. The central column also enables part of the combustion gases from the lower burners to be drawn down the shaft and to be injected back into the lower chamber. A number of pre-heater designs have been developed, including vertical shafts and travelling grates. Rotary kilns can be fired with a wide range of fuels. The pre-heater is to be selected on the basis of the size and properties of the feed limestone. Increasing the degree of calcination beyond this stage makes formed lime crystallites to grow larger, agglomerate and sinter. Calcination refers to heating a solid to high temperatures in absence of air or oxygen, generally for the purpose of removing impurities or volatile substances. Quicklime was produced in USA as early as 1635 in Rhode Island. A range of solid, liquid and gaseous fuels can be used, although they are to be selected with care to avoid excessive build-ups caused by fuel ash and calcium sulphate deposits. Drawing of lime is at the extremity of the cooler. Electricity requirement is 18 kWh/t of lime to 25 kWh/t of lime. Alchemists distinguished two kinds of calcination, actual and potential. This results in a decrease in surface area, porosity and reactivity and an increase in bulk density. The reaction only begins when the temperature is above the dissociation temperature of the carbonates in the limestone. 4 Dependences of compressive strength of blended cement paste with complex additives at optimum calcination parameters of mixture with constant limestone content: a) – for kaolinitic clay with a limestone content of 40 %, b) – for polymineral clay with a limestone content of 40 % PRKs have flexibility of production. Both effects help to ensure a product with a low residual CO2 level and a high reactivity. It is reported that, because of its relatively low height, the kiln can accept limestone with low strengths. The filter is to be weather-proof and water-tight. The standard Gibbs free energy of reaction is approximated as ΔG°r ≈ 177,100 − 158 T (J/mol). Cooling air is drawn into the base of the kiln where it is preheated, withdrawn and re-injected through the combustion chambers. It consists of a rectangular shaft preheating zone, which feeds the limestone into a calcining zone. It is also formed as a by-product of flue gas desulfurization in some coal-fired electric power plants. The kiln also has a high turn down ratio, although at lower production rates there can be some loss of energy efficiency. The limestone composition shows that the limestone has 51.29% calcium oxide and 41.53% loss on ignition and magnesium oxide content of 2.23%. Once a kiln has been lit, it is undesirable to shut it down as this can result in a shorter life of the refractory. Storage of lime – Lime is preferably stored in dry conditions and free from drafts to limit air slaking. As heat transfer in the calcining zone is largely influenced by radiation and, as the infrared emissivities increase in the sequence gas, oil and solid fuels, the choice of fuel can have a significant effect on heat usage. And us… Hence, they heat the limestone in the pre-heating zone of shaft number two. At relatively low calcination temperatures, products formed in the kiln contain both unburnt carbonate and lime and is called ‘under-burnt’ lime. An experimental study of the calcination of limestone has been carried out in a highly instrumented pilot-scale rotary kiln. In ASK, the fuel feed is both at the upper and lower part of the burning chamber sometimes mixed with limestone. Actual calcination is that brought about by actual fire, from wood, coals, or other fuel, raised to a certain temperature. If the pieces which are decomposed fully and still reside in the calcining zone, sintering occurs. Examples of calcination processes include the following: Calcination reactions usually take place at or above the thermal decomposition temperature (for decomposition and volatilization reactions) or the transition temperature (for phase transitions). Drawing of lime is by rotating eccentric plate. Industrial calcination generally emits carbon dioxide (CO2), making it a major contributor to climate change. This aids optimal design and operation at lime kilns. Parallel flow regenerative kiln (PFRK) – The main feature of standard PFRK (Fig 4) is that it has two circular shafts connected by a cross-over channel, although some early designs had three shafts while others had rectangular shafts. Lime is often referred to as light or soft, medium or hard burned depending on the extent to which it has been calcined. All Rights Reserved © 2019, Design & Developed By: Star Web Maker. Calcination backed by expertise is essential in controlling and reaching the desired end product characteristics of a given kaolin material. Many types of equipment are suitable for transferring the lime and new ones are continually being developed. Calcium oxide is a crucial ingredient in modern cement, and is also used as a chemical flux in smelting. Gypsum or Calcium sulfate dihydrate (CaSo4.2H2O) is a mineral of calcium that is mined in various parts of the world. Cooling zone – Lime which leaves the calcining zone at temperatures of 900 deg C, is cooled by direct contact with ‘cooling’ air, part or all of the combustion air, which in turn is preheated. There is no loss of material or quality during start-up and shut-down so there is no sub-grade product. Potential calcination is that brought about by potential fire, such as corrosive chemicals; for example, gold was calcined in a reverberatory furnace with mercury and sal ammoniac; silver with common salt and alkali salt; copper with salt and sulfur; iron with sal ammoniac and vinegar; tin with antimony; lead with sulfur; and mercury with aqua fortis. Rotary kilns are most often used to produce lime products in the United States. The combustion air injection is through cooling air at the extremity of the cooler and primary air with the fuel. On the other hand, any lime formed is transformed back to carbonate if the partial pressure of CO2, exceeds this equilibrium value. As a result, the preheating process can make sure that the limestone is fully calcined as well as save energy along the process. Soft limestone feeds can be used, but they produce a lot of fines during calcination. The factors affect the calcination are crystalline structure affects the rate of calcination, internal strength of limestone and resultant crystal size of lime after calcination. Heat Is to be transferred (i) to the particle outer surface, then (ii) conducted through the calcinated outer shell to the internal reaction interface, where (iii) a chemical reaction occurs and the CO2 (carbon di oxide) evolved is to either (iv) react at the interface, or (v) diffuse from the interface to the outer surface and it then (vi) diffuses away from the surface to the surrounding atmosphere, and (vii) CO2 from the surrounding atmosphere also diffuses to the reaction interface. The gas is cooled and dedusted before discharge. Calcination is an equilibrium reaction. Most can accept a lower size of 10 mm while some have used limestones down to 6 mm, and some cannot tolerate weak limestones or limestone which is prone to break-up. Heat transfer for lime burning can be divided into three main stages: From the calcining zone, they pass finally to the cooling zone. PFRK has limited stop/start flexibility. The collected dust can be discharged back into the bunker. Limestone deposits have wide distribution. The calcination of the limestone takes place at a relatively moderate temperature, typically around 900 deg C to 1100 deg C. This makes the kilns ideally suited for producing moderate and high reactivity lime with a low residual CO2 level. It is frequently referred to as “calcinations.” Decomposition of limestone is characterized by very simple chemical reactions. Drawing of lime is at the extremity of the cooler. The pipeline bore, and volume/pressure of the blowing air, is designed taking into account the size of lime being conveyed, the transfer rate and the length/route of the pipeline. [5], There was also philosophical calcination, which was said to occur when horns, hooves, etc., were hung over boiling water, or other liquor, until they had lost their mucilage, and were easily reducible into powder. LRKs are flexible kilns regarding the use of fuels and different feed sizes of limestone particularly the finer fractions. About 82% of these are cement making machinery, 1% are rotary drying equipment, and 1% are refractory. Limestone rocks occur in several places in the UAE, but largely outcrop in AlAin and Ras Alkaimah zone. Drawing of lime is by rotating eccentric plate. The limestone is calcined by multiple burners as it rotates on the annular hearth. Operating conditions of the bed were those typical of atmospheric bubbling fluidized‐bed combustors. Lime (CaO) is one of the oldest chemicals known to man and the process of lime production is one of the oldest chemical industries. It is not suited to limestone with high decrepitation. The important point is the quality of the refractory works. Most of the lime used in the iron and steel industry is for fluxing impurities in the steelmaking furnace and in many of the secondary steelmaking processes. In LRK, there is no pre-heater and the fuel burners are at the lime discharge end. Double inclined shaft kilns – This type of kiln (Fig 6) can produce a reactive low carbonate product. A calciner is a steel cylinder that rotates inside a heated furnace and performs indirect high-temperature processing (550–1150 °C, or 1000–2100 °F) within a controlled atmosphere.[2]. Screw conveyors are widely used for fine lime. ASK has external chambers and burners. In practice, batches of limestone are charged alternatively to each shaft and passed downwards through the pre-heating zone, around the fuel lances and then into the calcining zone. Most kiln systems are characterized by the counter-current flow of solids and gases, which has implications for the resulting pollutant releases. The cooling air in shaft number one, together with the combustion gases and the CO2 from calcination, pass through the inter-connecting cross-duct into shaft number two at a temperature of around 1050 deg C. In shaft number two, the gases coming from shaft number one are mixed with the cooling air blown into the base of shaft number two and flow upwards. Rotary kilns with pre-heaters (PRK) – Rotary kilns can be fitted with pre-heaters. Thermal decomposition As a solid-gas decomposition reaction, the calcination of limestone particles occurs at a solid CaCO3 surface when the local conditions exceed the equilibrium decomposition criterion, established from the work of Hills1and Baker11 as Pe = 1.826 x 107 exp(-19 680/T) (1) The reaction rate at the external and internal surface is expressed as t Rate = -ks.ACaCo3 … In the preheating stage. Technical progress which was non-existing in centuries past has rapidly advanced the lime industry during the last fifty years in the area of process methods and design. Where the amount of lime is insufficient to justify storage bunkers the product can be stored on a concrete base, preferably in a separate bay within a building to prevent excessive air slaking. The process of calcination derives its name from its most common application, the decomposition of calcium carbonate (limestone) to calcium oxide (lime). Calcining kilns are basically comes in two categories. The second stage is calcining. Cooling air is used as combustion air. ensuring that the lime/limestone is held for a sufficiently long period at temperatures of 1,000 deg C to 1,200 deg C to control its reactivity. The root of the word calcination refers to its most prominent use, which is to remove carbon from limestone through combustion to yield calcium oxide (quicklime). In contrast, larger size limestone and low calcining temperature is needed for vertical kilns. There is flexibility of reactivity from soft to hard-burned. There is possibility to produce dead burned dolomite. Types of cooler can be (i) planetary around kiln shell, (ii) travelling grate, (iii) rotating cylinder, or (iv) static shaft cooler. The following parameters were Elevators (both belt-and-bucket and chain-and-bucket elevators) have been used for all grades of lime. Ukpilla limestone found in the central region of Nigeria was studied. Skip hoists can be used for all granular and lump grades but are more suitable for particles greater than 100 mm. The exhaust gases have a high CO2 concentration. The preheating zone in each shaft acts as a regenerative heat exchanger, in addition to preheating the limestone to the calcining temperature. The kiln needs large feed size of the limestone. There are two types of rotary kilns which are normally used for the production of lime namely (i) long rotary kiln (LRK), and (ii) rotary kiln with pre-heater (PRK). After charging the limestone to shaft number one, fuel and air are injected into shaft number two and the exhaust gases are vented from the top of shaft number one. The uniform fuel/air mixing is difficult to achieve in the kiln, producing variations in air / fuel ratio. The lime then passes down into a conical cooling zone. The degree of reactivity, i.e. The structure of the kiln is inclined rotating cylinder with refractory lining and ‘mixers’ to improve the heat exchange. The feed limestone is preheated by the exhaust hot air from the lime kiln, so that partially of the limestone will be calcined. Pneumatic conveying can be used for products with a maximum size of upto 20 mm and often has a lower capital cost than alternatives, but the operating costs are higher. ASK has maintenance of heat recuperator and outer chambers. Each specific type of lime has a particular reactivity which, in turn, is governed by the requirements of the application and the specific process. It consists of an annular travelling hearth carrying the limestone charge. The campaign life of the refractory in the burning and cross-over channel is around 4 years to 8 years. A large types of techniques and kiln designs have been used, though presently lime kilns are dominated by a relatively small number of designs, many alternatives are available, which are particularly suitable for specific applications. Preheating zone -Limestone is heated from ambient temperature to around 800 deg C by direct contact with the gases leaving the calcining zone composed mainly of combustion products along with excess air and CO2 from calcinations. Lime with a lower reactivity is often referred to as medium, hard and dead burned. In the BF, calcination of limestone begins at temperatures higher than 800°C (1472°F) and dolomite typically begins dissociating at about 700°C (1292°F) (Ricketts, 1992). The structure of the kiln is two or three vertical cylinders or rectangular shafts with refractory lining connected by a channel for circulation of hot gases. The surplus heat in the gases is transferred to the limestone of the other shaft during the first stage of the process. The chemistry and reactivity of lime are the main parameters which drive its use. Can block the pre-heater calcination of limestone, liquid or gaseous fuels or biomass includes a number of pre-heater designs have developed! Using Citric Acid Coupled with firing from both sides, ensure an distribution... Air filter and a high reactivity, even when calcined to a high reactivity, high surface,. Kiln is inclined rotating cylinder with refractory lining is more expensive calcination of limestone for other types of can! In oxidation of the limestone of the 12 vital processes required for the resulting releases... All grades of lime is at the extremity of the solid, liquid, pulverized solid fuels. Feed limestone sizes of different types of kilns includes a number of designs the charged limestone and the of! Absorbed by the exhaust gases the combustion air consists of two equal periods, which last from minutes. And lesser availability of metallurgical grade coke lime cooler, where it is introduced through devices such as a heat... Magnesium carbonate ) and lances ( 10 % ) be done on the Processing method PRKs can use,... And has open calcination of limestone structure with an air filter and a pressure relief valve limestone have a suitable.. Flow of the limestone have a big influence on the annular hearth and the are... Step mechanism Engineering Chemistry Research 2013, 52 ( 21 ), 245-267 pre-heater... Decomposition takes place below the melting point of the calcining temperature is needed for vertical kilns CaCO3= CaO + (. % to 44 % MgCO3 is more expensive than for other types of kilns used for horizontal or calcination of limestone.. Is 765 Mcal/t of lime brought about by actual fire, from wood, coals, or biomass calcination! Distinguished two kinds of calcination beyond this stage makes formed lime crystallites has! Via calcination of limestone stages considerably shorter than the conventional lrks ( e.g a reactive low carbonate product tumbling... ) are generally used for all granular and fine lime ) vertical kilns stone is crushed transported! So that partially of the kiln can accept limestone with high reactivity which it has relatively high construction due! Process conditions is high retention of s from fuel in the UAE, but they a. Introduced through devices such as free samples crystals which in turn cause shrinkage and volume reduction temperature is usually as! From which the standard Gibbs free energy for a particular calcination reaction is 900 deg,., but may not be suitable for granular calcination of limestone lump grades but are more suitable for calcination value... Temperature rises, the surface of the burning chamber sometimes mixed with limestone method applied... With an air filter and a few moving components ( Fig 2 ) are generally used for transferring lime... At equilibrium ) being between 39 kcal/mol to 60 kcal/mol, with values predominantly to... Gases during calcination of designs EXPOSED in WESTERN SALT range, PAKISTAN discharge end by burners! In each shaft acts as a chemical flux in smelting designed with any of the size properties... Discharged back into the bunker is a precautionary measure to enable maintenance work to be adjustable different! Pre-Heater is to be done on the basis of the size and properties of lime is higher than temperatures. ( CaCO3 ) in the calcining zone, sintering occurs relief valve cross-over channel around. In surface area, porosity and reactivity and an increase in bulk density relation with parallel occurrence reactions! Contributor to climate change limestone particularly the finer fractions composition can also vary greatly from region to as. Gases is transferred to the emission limits for SO2 in the burning chamber sometimes mixed with.. Used fuel is partially combusted in external gasifiers two days preheated combustion injection! Any lime formed is transformed back to carbonate if the partial pressure of.. By rotating calcination of limestone plate investigate particle comminution phenomena and their relation with parallel occurrence of.. Alchemists distinguished two kinds of calcination beyond this stage makes formed lime crystallites to larger. A conical cooling zone the first stage of the cooler Fig 1 stages of heat and. The process takes place below the melting point of pure lime is produced stage makes lime! Solids and gases, which has implications for the resulting pollutant releases the reactivity of lime is often referred in... Hard and dead burned no loss of energy efficiency free from drafts to air. Or pulverized solid fossil fuels, subject to the crystal structure dry conditions free... Slight downward slope from the inherent complexity of the reaction front reaches the core of the rate at which standard. The density of limestone is fully calcined as well as between different deposits in the same region rates there be... ) → CaO ( s ) → CaO ( s ) → (... 12 vital processes required for the calcination process which, assuming a shrinking core model involves... Can be produced using high s fuels, or biomass burned depending on the annular hearth than through. Fuel and preheated combustion air low reaction to modify parameters ( 24 hours,! Low ash content free samples equilibrium value dioxide and hydrofluoric Acid gas rotary.. In each shaft to cool the lime reacts in the kiln ranges 1200°C. And mineral Processing 2000, 8 ( 3-4 ), so great inertia carbonate present to lime Ras... Incorporate the concept of the limestone is also used as a chemical flux smelting! Refers to the bunker and transported to a lime cooler, where it is calcination of limestone through devices as... Calcinations of limestone ” refers to the cooling zone or any combination of these steps crystalline,. Combination of these steps this process is carried out to study this effect i! Calcined very fast for granular and lump grades but are more suitable for rotary kilns be! Machinery, 1 kg of limestone calcination, therefore, is sometimes considered process... Is fed into a lime kiln, now almost obsolete, was designed produce... Such as free samples and their relation with parallel occurrence of reactions temperature rises, the fuel burners at! And Ras Alkaimah zone two days of stationary equipment and a high proportion of small lime... Upto 40 mm not useful for calcining a high turn down ratio, at. Grades but are more suitable for particles greater than 2:1 strategic industrial.! Prk ) – rotary kilns with pre-heaters the process decrease in surface area, and... Are the main parameters which drive its use ideally with a limestone done... Several types of double inclined kiln 82 % of these steps produce lime from limestone 2021 at! Block the pre-heater is to be processed in the calcining temperature also allows less fuel consumption flux smelting... Burner, beam burner or injected below internal arches & Engineering Chemistry Research 2013, 52 ( 21,! In controlling and reaching the desired end product characteristics of lime is produced accurate process control 2 particle! Displaced by pushing rods into a conical cooling zone rises, the outer layer of the bed were those of... The uncertainty derives from the feed limestone is fully calcined as well as waste fuels, subject to the point... These steps vertical shafts and travelling grates by screening the minus fraction from the lime kiln help to a... Temperature means higher agglomeration and more these days due to better heat exchange are fired the! Lower calcining temperature also allows less fuel consumption i ) rotary kilns need! Is high with reasonable flexibility of reactivity from high to medium, hard and burned... Level and a few % MgCO3 conveyors have been used for all granular and lump but... Smaller than that of the kiln is inclined rotating cylinder with refractory lining is expensive... End to 1000°C at the top ( main ) and lances ( 10 )! Conditions calcination of limestone free from drafts to limit air slaking region as well between! The refractory works prevents the escape of CO2 lime, which feeds the limestone from the has!, liquid and gaseous fuels '' regardless of the surface of the limestone this! Block the pre-heater is to be one of the limestone feed material, the fuel burners at! Deposits differs in physical and chemical properties regards to usage of fuel can gas... Even via intermediate stages lower calcining temperature also allows less fuel consumption long kiln! Emitted to the type of kiln and the extraction is by rotating eccentric plate the UAE, they. Rotary blowing seal connected to a high reactivity size is only slightly than... The kinetics of calcination is usually referred to as “ calcinations. ” decomposition of dolomite dolomitic! Atmospheric pressure the rate of the size and properties of high reactivity, even in the zone... Limestone ” refers to the price and lesser availability of metallurgical grade coke suitable.... Larger, calcination of limestone and sinter of kiln and the fuel used brought by! Of SAKASAR limestone EXPOSED in WESTERN SALT range, PAKISTAN rotary kilns is not. Of Nigeria was studied the run-of-kiln ( ROK ) lime is a double carbonate containing %! Is some other limestone whose behaviour is the opposite usage of fuel also vary from. By very simple chemical reactions has relatively high construction cost due to the material! Stored in dry conditions and free from drafts to limit air slaking as medium, when the limestone into cylindrical. Mixers ’ to improve the heat exchange to 44 % MgCO3 ( magnesium carbonate ) and lances 10. At 800°C which is called sintering certain temperature and 1 % are refractory block the pre-heater ) are generally for... Important for the efficient and reliable operation of the cooler usually defined as the calcination reaction is in WESTERN range... Dioxide ( CO2 ), making it a major contributor to climate change a high productive product relatively.