In cement plant, one of the major component for clinker or cement formation is limestone. Dispatch, storage and processing of limestone can be divided into five main operations: i.e. crushing/grinding, sizing, benefication, storage/loading-out & transport. For cement production, limestone is first reduced in size by processing through a series of crushers and grinders and then limestone storage is done under covered sheds to get rid of cement industry impacts such as environmental Issues, health & safety issues and many more.
Clinker Storage:
Clinker storage
After limestone is reduced in size by processing, the stored limestone is then mixed with some mineral aggregates (siliceous, aluminous, and ferrous materials) and water in high temperature kiln to form clinker. After cooling, clinker storageis done under covered sheds or clinker dome. The nodules of cement clinker are then ground to the consistency of face powder to produce powdered cement.
Cement Industry Impacts & Management for Limestone & Clinker Storage:
The cement maufacturing industry exhibits various issues associated with cement and lime manufacturing, which occur during the operational phase. Emissions associated with intermediate and final materials handling and storage are responsible for the followings industrial Impacts :
Environmental issues
Air Emissions
Energy consumption and fuels
Wastewater
Solid waste generation
Noise
Labor Health & Safety
Safety from Dust
Safety from Heat
Safety from Noise & vibrations
Physical Hazards
Safety from Radiation
Environmetal Health & Safety
Hindustan Alcox Limited specializes in providing storage solution for limestone with long span steel structure to get rid of above-mentioned cement industry impacts. Limestone storage shed, engineered by the Hindustan Alcox Limited is the best available choice to cover limestone stockpiles for the most challenging environment. Clinker storage sheds or Limestone storage sheds are often built over operating stockpiles so that construction may proceed efficiently without interrupting operational work.
The most common raw materials used for cement production is limestone, which is usually extracted from a quarry adjacent to or nearby the cement plant. The selected limestone is then crushed, ground, and proportioned so that the resulting mixture has the desired fineness. Stocking of limestone in covered Limestone storage system not only minimizes the problems (like caking, particle segregation etc) but also improves plant efficiency and maintains quality of limestone.
Clinker Storage:
Production of cement is considered to be a dry process with multi-stage suspension preheating and precalcination (where calcium oxide is burn with silica, alumina, ferrous compounds and others & produces another intermediate compound known as clinker). The clinker storage can be kept as open or closed (under clinker storage shed) type. The nodules of cement clinker are then grinded with other additives like gypsum, sulphur to produce powdered cement.
Loss Prevention And Damage Control Measures in cement production:Cement is a basic construction material for building and civil engineering. The cement industry is an energy intensive industry & output from the cement industry is directly related to state of the construction business along with some factors related to loss prevention of resources like limestone , gypsum, clinker etc. Many cement plants have followed general primary measures, such as process control optimization, solid fuel feed systems, optimized cooler connections and use of optimized power management systems, but forgotten to imply the prevention and damage control measures, which exhibits very essential base for the implementation of a quailty cement production. The Loss Prevention And Damage Control measures are as follows:Prevention of Caking i.e. Full or partial solidification of resources.Elimination of Particle Segregation Problem.Removal of Moisture Problem.Prevention of Flow Blockage Problem.Suppress the Chemical Oxidation of Resource.
After considering prevention and damage control measures, the proportionate distribution of clinker, gypsum and fly ash is done by electronic weigh feeders. In modern cement plants, clinker and gypsum are precrushed in a roller press and subsequently fed into ball mill for fine grinding. The installation of roller press technology is very beneficial in terms of both quality and energy conservation. The cement produced from roller press is showing better particle size distribution in cement (and hence good strength development) and consumes less power. The resultant product is called cement.
Cement is a basic building material produce by cement plant. Creation of cement goes through some crucial steps with each step involving creation of intermediate compounds and finally produces cement.
The first foremost step in cement manufacturing process is calcinations of Calcium Carbonate (CaCo3), which can easily available in form of Naturally occurring calcareous deposits such as limestone, marl or chalk. The Calcinations of Calcium Carbonate produces Calcium Oxide as intermediate compound for the next step.
In the Second Step, the produced calcium oxide is burn with silica, alumina, ferrous compounds and others & produces another intermediate compound known as clinker. The clinker storage can be kept as open or closed (under clinker storage shed) type. The nodules of cement clinker are then grinded with other additives like gypsum to the consistency of face powder to produce powdered cement.
More than adequate amount of raw materials are required to produce adequate amount of clinker along with the energy consumption in form of heat. From the above procedure involved in the manufacturing of best quality cement, we need to:
Preserve the resources from getting degraded
Bear losses in form of waste produced during intermediate processes
Preserve the resources like petcoke, coal required to produce heating effect
Uplift or Maintain brand quality by producing best quality of cement
Why Clinker or Limestone Storage Sheds?
Limestone Storage
Many cement plants have adopted primary measures such as optimized process control, use of modern fuel feed systems, adequate cooler connections & power management systems, to avoid all such dangers. However, those primary measures are not sufficient to improve cement production in any cement plant.
In order to get rid of all the above-mentioned liabilities, it is the key responsibility of owner of cement plant to leave no flaw in producing best quality cement and sustain its brand value in the market, which can be accomplished by using Clinker or Limestone Storage Sheds over cement plants under operation.
Hindustan Alcox Limited specializes in providing storage solution for limestone with long span steel structure having span of up to 150 m & height of up to 40 m. Limestone storage shed, engineered by the company is the best choice to cover stockpile for the most challenging environment. In cement plant, Clinker storage sheds or Limestone storage sheds are often built over operating stockpiles so that construction may proceed without interrupting operations.
A hemi-spherical structure with the curvature on top, when usually created to cover a sufficient room for bulk storage like cement, limestone, coal, lignite, gypsum, additives and many more. Depending upon the industrial purpose, followings are the storage domes with their advantages in industry: ‘Domes for power generation’, ‘Domes for Warehousing & dry storage’.
We, At Hindustan alcox limited, one of the dome manufacturers use the combination of basic features of dome structure and latest technology to make dome structure more functionally suitable and highly versatile in installation/reinstallation as well as in maintenance.
Domes for Warehousing & Dry Storage
In industrial bulk storagefor large quantities of materials such as cement, fly ash, clinker, limestone and other fertilizers, maintenance of product integrity is a primary objective. Open stockpiles leave materials subject to degradation during storage. But storage domes are very helpful in maintaining product integrity as well as elimination of various other hazards. Various type of domes used for warehousing and dry storage are as follows:
Limestone Dome:
Cement is an inorganic, non-metallic substance used as a bonding agent in building materials by virtue of its hydraulic binding properties. Limestone, chalk and clay are the most common raw materials used in cement production. Limestone provides the required calcium oxide and some of the other oxides.
For cement production, limestone is first reduced in size by processing through a series of crushers and grinders. This fine powdered form of limestone is then mixed with some mineral aggregates (siliceous, aluminous, and ferrous materials) and water in high temperature kiln to form clinker. After cooling, the clinker will be stored in the clinker storage. The nodules of cement clinker are then ground to the consistency of face powder to produce powdered cement.
Flexible: Flexibility of limestone storage can be seen by its capability to cater maximum Space for storing limestone & how versatile it is with additional storage of various additives used in cement production. These domes not only covers large span to facilitate the storage of various additives under same shed but also its future development can also be done if more space is needed.
Quick and Facilitating: Material handling of Limestone is based on various operations like loading, unloading, transportation, storing and feeding. In cement production industry, these different process stages may be in different locations, and each may have various feed conditions. Processing system will perform efficiently only when there is a proper set up for materials storage and handling. Limestone dome provides opportunity to get an efficient setup for material storage and handling process to utilize maximum space and also helpful for labor to have convenience in almost all operational works. All such facilities under single dome not only make the cement plant operation handy & hasty but also maintain energy efficiency level.
Dome structure is a hemi-spherical hollow structure, used as roofing/ ceiling. Earlier Domes were only used in constructing Architectural buildings, but with the passage of time their importance to endure under adverse climatic conditions is understood and now domes can be seen in almost every sphere of construction industry. In other words, a semi-spherical structure with the curvature on top, when usually created to cover a sufficient room for bulk storage like cement, limestone, coal, lignite, gypsum, additives and many more. Depending upon the material used for storage, followings are the storage domes with their usage in industry:
a) Slag Dome:
Slag is metal-separated stony waste material in form of their metal oxides mixed with silicon di-oxides. Industrially, its storage in Slag dome is generally carried for Metal ore smelting process to serve some useful purpose like ‘temperature control in Smelting’, ‘preventing re-oxidation of molten metal’, ‘removing waste from smelting process’.
Usages:
Slag dome is useful in sustenance of its compaction characteristics of slag.
Slag dome is also useful in keeping low risk of breakability and maintenance of maximum strength.
b) Additive Dome:
Additives are organic material added to subject material in purpose to improve its inherit properties, performance, efficiency and reduce cost. Industrially, Additive storage covers a wide range of additives like antifoams, organic additives and other performance enhancement additives. Some well-known examples of additives are ‘fly ash’, ‘GGBFS’, and ‘silica fume’.
Usages:
Additive dome covers large span to facilitate the storage of various additives under same shed.
Storing Additives under domes facilitates maximum utilization of space in plant which may be used for other industrial purpose too.
Ventilation facility and prevention from adverse conditions of environment under additive dome will eliminate the problem of oxidation, which causes clinical effects in labor.
c) Gypsum Dome:
Gypsum storage
Gypsum is fine-grained calcium sulphate (CuSo4) material industrially used as fertilizer/enhancer in subject material to improve its inherit qualities, performance, efficiency and reduce cost.
Usages:
Gypsum storage is very useful in controlling fugitive emission of gypsum.
Storing Gypsum under domes facilitates maximum utilization of space in plant.
Gypsum dome also helpful in prevention from vulnerability caused by adverse environmental conditions and rainfall.
d) Clinker Dome:
At sintering stage in cement manufacturing process, a nodular material is formed known as Clinker. In the Cement plant, Clinker is prepared by fusing various clays and limestone with additives by melting them below to the point of liquidation. ‘Silica fume cement clinker’, ’pozzolana cement clinker’, ‘ground granulated blast furnace slag cement clinker’ are most commonly formed Clinkers.
Usages:
Clinker dome has a benefit of facilitating no spillage and zero dust pollution. This will not only prevent wastage of resources but also create health friendly environment for labor.
Clinker storage under dome also help in prevention from heat which further facilitates setting up hot clinker to its favorable temperature before being converted into its grinded form, known as cement.
Clinker storage protects clinker from being affected by Rainfall or heavy thunderstorms, which can harm the quality of clinker.
e) Cement Dome:
Bulk Storage Dome
The grinded form of clinker is cement. Cement is used as binding material that combines with water and other additives and sets to bind two other materials together. That is why it also called as Hydraulic binder. White cement, pozzolana cement, acid resistant cement, blast furnace cement, sulphate resistant cement, rapid hardening cement, quick-setting cement, high alumina cement, colored cement are some common types of cements in construction industry.
Usages:
Cement dome are highly non-vulnerable to maintain moisture and water resistance in heavy rainfall areas.
Maintenance of temperature and adequate ventilation system is recommended for large scale storage, which can be fulfilled under cement dome.
Cement storageare useful in providing maximum utilization of space in plant, which fulfills need of efficient loading and unloading of cement in order to feed power stations continuously.
f) Limestone dome:
Limestone is composition of calcium carbonate, CaCo3 with other minerals, generally found in organic sedimentary rocks formed from accumulation of shell, forms, coral etc. In clinker/cement formation, limestone is used as one of the major component. Moreover, In precious Architectural works, limestone is also used neutralize the effect of acidity caused by acid rain.
Usages:
Limestone storage costs less as compared to reinforced concrete silo for storage. Therefore limestone dome gives you economical storage solution.
Limestone dome provide best protection against moisture and rainy weather, as limestone is highly susceptible to moisture.
f) Coal/Lignite dome:
Extracted from the ground by coal mining, coal is the biggest source of energy for the worldwide electricity generation. In simple terms, there exist four types of coal – peat, lignite (brown coal), bituminous, and anthracite(highest quality coal). Coal/Lignite storage is done in large quantities and requires stacking in open areas. ‘Production in mild climatic condition and market it in winter season’, ‘Feed the thermal power stations continuously’ are some of the key reasons for coal storage, which we understand the most.
Usages:
Coal/lignite dome are made in such way to prevail cross ventilation at very corner inside it which can be done to prevent heat accumulation.
Coal domeprovide best protection against moisture and rainy weather since coal is vulnerable to moisture.
The storage of (Cement, Clinker, Slag, Limestone, Additives, Gypsum and other industrial materials) in large quantities is reffered as bulk storage. Handling of bulk storage is process of movement, storage, control and protection of industrial material throughout the process of manufacturing, distribution, consumption and disposal. Followings are the major issues to be faced in storage, handling and transport of bulk solids powders and other dry material:
Additive storage
Emission from storage:: The storage, and transport of Industrial Material like limestone storage, gypsum storage, cement storage for long duration produces emissions of volatile organic compounds (VOCs), nitrogen oxides (NO), carbon monoxide (CO) and other toxic air pollutants. These toxic emission are not only threat to lives of labour, but also harmful for our ecosystem.
Moisture problem: Increase in moisture content in bulk storage not only affects the intrinsic properties of material but also gives rise to its reactive tendency with other chemicals.
Flow problem: The most common problem in operating bulk storage is flow blockage. It largely depends upon bulk density, particle size and moisture content in the material.
Particle Segregation Problem: Existence of moisture content in material for a long time causeserratic feed & variation in particle size (segregation) which leads to increased energy consumption and reduced mill performance.
Caking Problem : Fully or partial solidification of bulk solids like (cement, limestone) by virtue of adsorption, crystallisation, adsorption after a long storage time. Heat and exposure to dry air will exacerbate caking. Persistence of such problem increases the manpower and time needed for disaggregation of unwanted aggregated material.
Chemical oxidation : Some of the industrial material are oxidative in nature and their chemical oxidation rises with the rise in temperature, which causes loss in the intrinsic properties of material.
Storage is meant to be of two types: Low-capacity bin storages and High-capacity bulk storage. Unlike bin storages, Bulk storage is storage of (Cement, Clinker, Slag, Limestone, Additives, Gypsum and other industrial materials) in large quantities. Followings are the various types of bulk storage depending on the material to be stored for industrial purpose:
a) Slag Storage:
Slag is metal-separated stony waste material in form of their metal oxides mixed with silicon di-oxides. Industrially, Slag storage is generally done for Metal ore smelting process for serving various useful purpose such as ‘temperature control in Smelting’, ‘removing waste from smelting process’, ‘preventing re-oxidation of molten metal’.
Few facts:
Each year, more than 400 million tonnes of iron and steel slag is produced.
In some countries, up to 80% of the cement contains granulated slag, as it helps to bring down the cost of cement.
According to the Slag Cement Association, 59% of the embodied CO2 emissions can be saved by replacing Portland cement with slag cement in concrete.
Advantages:
In most Countries, Slag Storage is used as energy saving material. Therefore, It mainly helps in reducing heating and cooling cost in industries.
Slag storage is helpful in improving compaction characteristics of cement placement.
Slag Storage under sheds is also helpful in keeping low risk of breakability and maintenance of maximum strength.
Additive storage
b) Additive Storage:
Additives are the organic material added to subject material in order to improve its inherit qualities, performance, efficiency and reduce cost. Industrially, Additive storage covers a wide range of antifoams, organic additives and other performance enhancement additives. Some well-known examples of additives are ‘fly ash’, ‘GGBFS’, and ‘silica fume’.
Few facts:
In the United States, 95% of the masonry cement is made by adding additives to subject material like clinker , cement etc
In some countries, up to 80% of the cement contains granulated slag, as it helps to bring down the cost of cement.
Advantages:
Achieve high sustainability of plant by virtue of ‘less electrical consumptions’ and ‘natural resources preservation’.
Storing Additives like fly ash under shed do not require grinding and mixing, thereby nullify grinding cost to plant.
Some Additives like Sulphites are not only highly oxidant in nature, but also causes clinical effects in sensitive individuals. Cross ventilation quality and prevention from adverse conditions of environment across the Additive storage sheds will eliminate such difficulties.
c) Gypsum Storage:
One of the additives, called Gypsum is fine grained calcium sulphate material industrially used as fertilizer/enhancer in subject material to improve its inherit qualities, performance, efficiency and reduce cost. ‘Calcium sulphate di-hydrate’, ‘alabaster’, ‘plaster of paris’, selenite, rock gypsum, and gypsite are some well known gypsum examples used for gypsum storage.
Few facts:
Being the main ingredient in plaster of Paris (PoP), it is useful in making casts and sculptures.
90% of Gypsum is very soft that it could be scratch with our fingernail.
Most of the Gypsum often found in the mines of Australia, Mexico, US. Out of these three countries, largest ever gypsum crystals were found in Mexico, weighing 55 ton.
Advantages:
Gypsum storage sheds is very effective for prevention and control of fugitive emission.
Less operation and maintenance cost is required.
Prevention from vulnerability caused by adverse environmental conditions.
d) Clinker Storage:
Clinker is nodular material formed at sintering stage in cement manufacturing process. In the Cement plant, Clinker is prepared by fusing various clays and limestone with additives by melting them below to the point of liquidation. Most commonly formed Clinkers are ‘silica fume cement clinker’, ’pozzolana cement clinker’, ‘ground granulated blast furnace slag cement clinker’.
Advantages:
Clinker storage has an advantage of no spillage of clinker and no dust pollution. This will not only prevent wastage of resources but also create heath friendly environment.
Clinker storage also help in setting up hot clinker to its favorable temperature before being converted into its grinded form, called as cement.
Clinker has quality of moisture proof. The only thing can harm clinker is Rainfall or heavy thunder-storms, which can be easily prevented by clinker storage sheds.
e) Cement Storage:
Cement is grinded form of clinker. In construction, Cement is used as binder material that combines with water and other ingredients and sets to bind two other materials together. That is why it also called as Hydraulic binder. Various types of cements are pozzolana cement, blast furnace cement, rapid hardening cement, quick-setting cement, acid resistant cement, sulphate resistant cement, high alumina cement, white cement, colored cement.
Advantages:
Due to its high water resistant nature of cement, cement storage under sheds are highly non-vulnerable to maintain moisture and water resistance in heavy rainfall areas.
Large scale Cement storage are recommended to maintain temperature as well as ventilation system, which can be fulfilled under cement storage sheds
To feed power stations continuously, we need efficient loading and unloading of cement, which can be done though Stacker/reclaimer under cement storage sheds.
f) Limestone Storage:
Limestone (a composition of calcium carbonate, CaCo3 with other minerals) generally found in most organic sedimentary rocks formed from accumulation of coral, shell, forams etc. In construction Industry, limestone is used as one of the major components in clinker/cement formation. Moreover, In precious Architectural works, limestone is also used neutralize the effect of acidity caused by acid rain .
Advantages:
Limestone storage under steel sheds will cost about 40% less as compared to reinforced concrete silos. Therefore helps in overall cost cutting.
Steel used in limestone storage sheds is highly corrosion proof as well as water proof. Therefore operation process will be more reliable, long lasting and anti-corrosion.
Limestone storage under storage shed also provide best protection against adverse weather conditions.
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