Cement is one of the most commonly used and important building material around the world. The total cement production around the globe back in 1991 was 1.145 billion tones, the majority of which came from large cement plants with capacities ranging from 2,000 to 20,000 tones per day and was transported to the location of use in bags or in bulk (UNCHS, 1993). Back in 2002, the world consumption of cement was about 1.72 billion tones and it has been increasing at about 1% per annum. (Jankovic, & Valery 2004)
Undoubtedly concrete and therefore cement, as the basic ingredient, marked the construction procedures and forms during the 20th century.
The importance and extensive use of the cement becomes more evident by taking into account that only a handful of projects have been built without using cement somewhere in the design.
The cement industry is likely to maintain its current growth momentum and continue growing at around 20% to 25% in the medium to long term. Government initiatives in the infrastructure sector and the housing sector are likely to be the main growth drivers. Our cement consumption per year was only 65kg in FY2009 whereas, in India its 135 kg and in Pakistan its
130kg. So there is a lot of opportunity to grow in this industry. If the import duty structure of various cement products, e.g. finished cement, semi-finished cement and basic raw materials for cement (25%, 12% and 7% respectively) continues i.e. import duties is on
favor of the local manufacturers and the construction sector remains booming with smooth power supply than nothing to be surprised that cement industry will be the
most evolving industry in the next three to five years. The importance of the housing sector in cement demand can be gauged from the fact that it consumes almost 60%-65% of the country’s cement. If housing sector growth wanes, it would impact the growth in consumption of cement, leading to demand supply mismatch.
In fact, according to the World Business Council for Sustainable Development (WBCSD) (WBCSD, 2009) concrete, is the second most widely used product in the world just after water, which shapes our built environment.
The common technology which is widely used in our industry from the year 2003 is Portland Composite Cement (PCC) which is made following European Standard Methods (ESM). Earlier, Ordinary Portland Cement (OPC) had been used which was made following the American Standard
Method (ASM). PCC gives equal strength and durability like OPC. The basic difference between them is in the manufacturing technology. Only 65%-80% of clinker is required to produce PCC while 95% of clinker is required to produce OPC. So, worldwide PCC has become popular which
requires less clinker.
According to the same source, an estimated 30 billion tones of concrete were consumed globally in 2006, compared to 2 billion tones in 1950. Consequently, cement plays a curtail role in the global economy and the companies involved
must adopt innovative solutions that will enable them to maximize profitability in all fields but at the same time pay special attention to the environmental considerations that coexist with the cement’s production procedures.
For example, Shah Cement, a subsidiary of the country’s biggest conglomerate Abul Khaer Group is now in the top of the industry beating Heidelberg and Holcim by deploying a fleet of trucks in the main growth areas and building the best marketing network in
the country. Local companies are investing in backward linkages (captive power plants), have built big plants to reduce cost of production and have a fleet of trucks to carry the products right to the doorsteps of consumers. Quality-wise also, the local companies have made
rapid strides. Multinationals bear high overhead costs regarding salary, infrastructure, quality control etc. On the other hand, local companies are more focused to keep the overhead costs low. Multinationals are only concentrating in providing high quality products
. But local companies are concentrating in offering quality product with additional benefits like home delivery system, rebate, gifts etc. Local manufacturers have been pursuing more innovative and aggressive business strategy compared to
multinationals. Local manufacturers seek to seize large market by reaching mass people through economies of scale while multinationals cater the needs of specific group of customers by charging
high price through superior brand value and quality.
Cement is a manufactured product made by blending different raw materials and firing them at a high temperature in order to achieve precise chemical proportions of lime, silica, alumina and iron in the finished product, known as cement clinker.
Cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word “cement” traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made
from crushed rock with burnt lime as binder. The volcanic ash and pulverized brick additives that were added to the burnt lime to obtain a hydraulic binder were later referred to as cementum, cimentum, cäment, and cement. Cements used in construction can be characterized as being either hydraulic or non-hydraulic. Hydraulic cements (e.g., Portland cement) harden because of hydration, a chemical reaction between the anhydrous cement powder and water. Thus, they can harden underwater or when constantly exposed to wet weather. The chemical reaction results in hydrates
that are not very water-soluble and so are quite durable in water. Non-hydraulic cements do not harden underwater; for example
, slaked limes harden by reaction with atmospheric carbon dioxide. The most important uses of cement are as an ingredient in the production of mortar in masonry, and of concrete
, a combination of cement and an aggregate to form a strong building material..
Cement is therefore essentially a mixture of calcium silicates and smaller amounts of calcium aluminates that react with water and cause the cement to set (British Geological Survey, Mineral Profile, Natural Environment research council
GPCC can also try to renegotiate its contract with the customer to a ‘costs plus’ type of contract, where the customer pays a variable amount for the cement, depending upon market or company conditions. This would essentially be an agreement where the customer pays the
costs of producing the cement plus a fixed percentage, so that GPCC doesn’t lose on the contract. The potential benefit to the customer is that if costs go down or if industry demand goes
up, the customer has some cushions to price swings. In times of high demand, cement prices and supplies could be harmful to the customer. A ‘cost plus’ arrangement could be tied into an agreement where the customer maintains a
certain range of demand, so that the impact of demand, price and market swings are
lessened for both companies.
The requirement for calcium is met by using high calcium limestone (or its equivalent calcareous raw material) and clay, mudstone or shale as the source of most of the silica and alumina. Finished cement is produced by finely grinding together around 95% cement clinker with 5% gypsum (or anhydrite) which helps to retard the setting time of the cement.
The pricing of cement of various players in the industry are very close to one another. The factories which would be using captive power (which is cheaper and more reliable than grid power) and backed by uninterrupted clinker supply at competitive price
, are likely to be more cost efficient to emerge as the market leader
. Currently, the standard price of one bag of cement produced by the multinational cement companies ranges within BDT 370 to BDT 390 per bag. On the other hand, price of one bag of cement produced by the local companies‟ ranges
within the price bracket of BDT 340 to BDT 365.
The quality of cement clinker is directly related to the chemistry of the raw materials used. Around 80-90% of raw material for the kiln feed is limestone. Clayey raw material accounts for between 10-15%, although the precise amounts will vary.
The manufacturing of portland cement requires large amounts of fuel, energy and maintenance of physical equipment which accrues massive production costs for the manufacturing companies. It is important for managers at Gray Portland …show more content…
With a highly trained sales force, GPCC can have employees not only meeting new companies to create new accounts but learning and bringing new information to the company about the market that was not readily available before-hand.
Magnesium carbonate, which may be present in limestone, is the main undesirable impurity. The level of magnesia (MgO) in the clinker should not exceed 5% and many producers favour a maximum of 3%; this rules out dolomite or dolomitic limestones for cement manufacture.
All these companies are exporting in very low quantity to the neighboring countries (India and Myanmar) which are easily accessible through water transportation such as ships and mother vessels. Transportation cost is major concern to export cement. Thus exporting this product to countries which are
reachable through connecting water bodies is much more feasible in terms of cost and accessibility. High duty charge is one of the main stumbling-block of cement export. Cement manufacturers in our country produce cement by importing clinker from
China and Indonesia (mainly) at a high rate of shipping cost and duties which make the present cost structure impracticable to tap the export potentials for cement. If the government make the duty structure more industry-friendly by exempting some duties on exportable cement and granting cash incentives, cement exporting to SriLanka, Nepal, Bhutan and the Middle Eastern (ME) countries will be
feasible in future.
Other deleterious materials include excessive alkalis (sodium oxide, Na2O or soda and potassium oxide, K2O) which would be unacceptable because of durability problems with the concrete (due to the reaction of alkalis with some siliceous aggregates to form a swelling gel†).
The Australian cement industry which employs over 1600 people and produce over 10 million tonnes of cement regarding materials which is with an annual turnover in excess of A$2 billion. In Australian cement industry is
responsible for around 7.2 (Mt) per annum of greenhouse gas emissions.
Portland which is the most common and widely produced type of cement worldwide, is made of finely powered crystalline minerals, primarily composed of calcium and aluminum silicates which in the presence of water a paste is produced which when hardened it becomes of stonelike strength.
The Indian cement industry is subject by approximately 20 companies, which account for 70% of the total cement production in Indian cement .
Portland cements weighs 94lb/ft3 (which is the unit weigh of a commercial bag, or sack of cement) and its specific gravity varies from 3.12 to 3.16 (Edward g Nawy, reinforced concrete, a fundamental approach, Prentice-Hall 1985 ISBN 0-13-771643-5 01).
Other varieties include rapid hardening, low heat, sulfate resisting, and low-alkali cements.
The cement industry in North America has been struggling through tough times in recent years. It is hard to believe that cement volumes have fallen to their lowest levels since the 1980s. The Portland Cement Association has predicted modest growth in the US cement industry during
2011 - 12, and expects that 2013 will mark a watershed for the industry in terms of a substantive and sustained recovery in volume and company decisions to re-open in the context of harsh EPA NESHAP regulations (Maxwell-Cook 2011).
In addition, blended cements are produced by finely grinding Portland cement clinker with other constituents, such as blast furnace slag, natural pozzolanas, silica fume, metakaolin, siliceous fly ash, calcareous fly ash, limestone fines and shale (British Geological Survey, Mineral Profile, Natural Environment research council
The Indian cement industry having 300 mini cement plants and approximately 130 large cement plants. The total capacity of production of mini cement and large cement plants is approximately 167.36 million tons. This is indicate a main boost of the Indian export of
cement. The Indian cement production not just able to meet the domestic demand, But huge amounts to be also exported. A fair amount of clinker and cement by products be too exported by India. The quality of Indian
cement is so good , so present demand in international market is high
The cement production plants consist of the three following processes (Figure 1):
1. Raw material process 2. Clinker burning process 3. Finish grinding process
Figure 1: Cement production process
Source: Encyclopaedia Britannica 2007
Figure 2: Cement production process
Source: (UNIDO, 1994)
A schematic holistic overview of the processes that take place in order to manufacture cement is provided in Figure 2. …
The first step of cement’s production process is the extraction and preparation of the raw materials.
Australia is a little market by world standards it has a good quality supply of raw materials for cement producing. The industry has invest & work to stay globally competitive by modernizing plants and opening cement standards.
The raw materials needed in order to produce cement are mined from quarries (fractured limestone, argillaceous rocks, quartz stone, iron ore, bauxite, etc), after extensive geological surveys and chemical analysis
, in specific quantities and proportions.
The Indian cement industry is the leading producer after china which indicated 183 big cement plants and 360 mini cement plants.
They are then crushed and transported for storage at the cement plant. The cement’s raw materials contain lime (CaCO3), silica (SiO2), alumina (Al2O3) and ferrous oxide (Fe2O3) that comes primarily from limestone and clay (Edward g Nawy, reinforced concrete
, a fundamental approach, Prentice-Hall 1985 ISBN 0-13-771643-5 01).
Australian Cement plants are situated in local centers or in small rural communities. The industry employs more than 1600 people and produce over10 (mt) million tons of cementitious materials with an yearly turnover in excess of A$2 billion. In Australia, the industry is
responsible for approximately 7.2 (Mt) per annum of greenhouse gas emissions.
The quantities of raw materials to be used, depend on the chemical and mineralogical properties and the properties / requirements of the clinker that must be produced. If necessary minerals are added as required to either the clay or the limestone in order that the presence of the correct amounts of aluminium, iron etc is ensured (NZIC, 1998).
Australia cement is self-important to the diversity of skill and talent across to their business as well as their recruitment processes. It is seamless and deliberate system in order to attract and keep quality people
The objective of carefully processing the raw materials is that the constant composition of the raw feed entering the kilns is ensured and at the same time that the raw materials are finely divided and chemically well balanced.
The cement industry in India is the 2nd largest market later than China accounting for regarding 7% - 8% of the totality global production. It has a totality capacity of about 330 (MT) since of during the year finished 2011 - 2012.
This will result in a uniform composition cement which will bear predictable properties that are in accordance with the desired specifications for the final product. At the same time, a uniform mixture also ensures that the kiln temperature can be kept fairly constant, near the optimum burning temperature (ACI, 2001).
In the Indian cement industry huge cement plant is according to 183 plant and it’s install capacity is 234.3 (mt) peranum and as well there cement production is around 168.3 mtpa. Mini and white cement plant is 360 and set up power is 11.1 mtb . it’s production is 6.0 (mt).
After determining the appropriate composition of the load, the raw materials (for dry process cement production, Figure 3) are carefully mixed in appropriate ratio and homogenized to produce a uniform mixture ("flour"), which is to undergo grinding in order to reduce its size to a very fine powder mixture until more than 85% of the material is less than 90μm in diameter. Good mixing ensures uniform distribution of raw
materials to feed the crushing and grinding circuit and leads to the production of uniform quality clinker
In 2012 Australian cement industry turnover is recorded at A$2.15 billion And cement and clinker production is about 8.5 million tern.
The raw materials proportions are defined by three clinker quality indicators namely Lime saturation factor (LSF), Silica ratio (SR) and Alumina ratio (AR). The usual range of the aforementioned indicators are 0.92 - 0.98 for the LSF, 2.2 - 2.8 for SR and 1.2 - 2.0 for the AR. (Tsakalakis, 2009).
The raw material mixture that occurs from this procedure which is called "kiln feed", "raw meal" or "raw feed" is homogenized, preheated and then driven for receiving pyrometallurgical treatment in a heated by flame furnace that uses natural gas, oil, coal or alternative fuels and can reach very high temperatures of up to 2.000οC. This rotary kiln is a long steel cylinder up to 6 m (20 ft) in diameter and over 180 m (600 ft) long, inclined a few degrees from the horizontal level, rotating at 60 to 200 rpm.
Export of Indian cement may saw further growth of an predictable raise in production and level of utilization. The cement industry is predict to raise by 9% to 10% with bring stabilization in rates.
Kilns nowadays, have a production capacity that exceeds 5000 tons/day. The kiln feed enters the furnace at its higher end and is slowly driven downstream the length of the kiln by the combination of its inclination and rotation.
Australian cement is the nation's top dealer of cement and its products & services with the biggest dedicated sharing system in the cement industry.
(ACI, 2001). This mixture of about 80% limestone and 20% clay, is kilned (pyroprocessed) at a temperature of 1400 to 1600 οC (2550 to 2900 οF). At these temperatures and after a set of physicochemical processes and chemical reactions which cause the materials to fuse, clinker is produced, which forms the basis for the preparation of any kind of cement (Lafarge, 2013).
In the year 2012 the Indian cement production 247(mt) million turn.
The raw materials react at these high temperatures forming 3CaO•SiO2 (tricalcium silicate), 2CaO•SiO2 (dicalcium silicate), 3CaO•Al2O3 (tricalcium aluminate) and 4CaO•Al2O3 Fe2O3 (tetracalcium alumino-ferrate) (NZIC, 1998).
The market for Australian cement ranges from 8.5 mt to 10.5mt and it’s manufacturing capacity is about 10.5 mt to 11.5 mt. This show productive capacity. The amount of cement production Is record at 10.27 mt in 2011-2012 and it’s averaged 9.29 mt , throughout the
10 years through 2012-13.
The rate that the mixture passes through the kiln is controlled by the rotational speed and the slope of the kiln. Clinker is a bead shaped, gray-green color material of 3-25 mm diameter. Clinker is then quenched (from approximately 1000oC to 150oC) with forced air flow, via perforated plates in the base of a large cooler.
During the year 2011 the blended cement recorded for 75% of whole cement production in the country.
The plates within the cooler, slide back and forth, shuffling the clinker down the cooler to the discharge point, from where it is transported to a storage area (NZIC, 1998).
The last step of the cement production procedure, is the grinding of cement, a highly energy intensive procedure.
Currently, multinational cement companies are facing intensive competition with local companies. Lafarge, Cemex, Holcim and Heidelberg are among the top ten cement companies in the world, but together they make up only around 27% of the Bangladesh market. Scancement of Heidelberg Group is the biggest among the foreign companies
, but its market share is Around
9.3% despite it has been in Bangladesh for nearly a decade. Holcim’s market share is around 6.4% despite it bought three plants in quick succession more than half a decade back as it planned to emerge as the top player in the country
. Lafarge and Cemex, the world’s first and the second largest cement companies have been
struggling to survive in the industry
. Local companies are grabbing the top slot of the industry by operating in economy of scale and with deft marketing strategy.
Clinker with a small amount of gypsum (CaSO4•2H2O), a form of calcium sulphate which is added to the clinker to regulate how the cement will set (set retarder) (Edward g Nawy, reinforced concrete, a fundamental approach, Prentice-Hall 1985 ISBN 0-13-771643-5 01), is ground for approximately ½ hour in large tube mills, into a very fine grey powder known as cement. In this step, various other mineral materials that do not degrade the properties of the final product may be added to the mixture alongside the gypsum, which are called additives or cement additions.
The cement and other products sectors has attracted to FDI value US$ 2,625.90 million among April 2000 to November 2012, according to the data available by the Department of Industrial Policy and Promotion .
Using additives which are of natural or industrial origin in different proportions, specific types of cement can be produced. These additives give the cement specific properties such as improved workability, greater resistance to sulphates and aggressive environments, reduced permeability, or higher-quality finishes.
Cement manufacturers in India are increasingly using alternate fuels it is not help to decrease production costs of cement companies, but it is prove effective in reducing emissions .
The cement is finally stored in silos until it is bagged or shipped in bulk to customers / sites, where it will be used. (Lafarge, 2013).
The previously mentioned raw feed preparation and clinker burning processes, are independently classified into the wet process and the dry process.
Considering the „Life cycle of the industry‟, currently cement industry of Bangladesh is in the growth stage. Sales of cement are increasing due to growing demand for cement in both the local and foreign markets. The industry realized
about 30% and 21% growth in 2009 and 2010 respectively after suppressed demand from previous years. Industry expected demand growth is 20%-25% for the next three years based on the assumptions below.
These processes are selected based on the properties of the raw materials available for use, the fuel costs, the local conditions and more. During the dry process that was described in a previous paragraph, crushed raw materials are dried in an approximately 20 m length and
2 m diameter cylindrical rotary drier, proportioned by an automatic weigher, mixed, ground and placed in adequately constructed storage tanks so they can then be fed to the kiln for the clinker burning process, in a dry state.
During last five years almost 32 cement companies have been shut down due to inadequacy of raw materials. Its too difficult to the small manufacturers to survive in the industry due to the shortage of raw materials since small companies face difficulties to arrange the raw materials in competitive price
. Currently, the basic trend in cement industry is smaller
companies are shutting down and the bigger companies are becoming bigger. Only 10-15 companies are holding 80% of market share.
In comparison with the dry process, in the wet process, the raw materials which have been properly proportioned using an automatic weigher, are ground (crushed to a diameter of approximately 20 mm) and thoroughly mixed in an appropriately predefined ratio with water being added, so it can be later fed into the kiln in the form of "slurry" (containing enough water to make it fluid). Water is added to the mixture while a combined tube mill with a length ranging from
10 to 14 m and a diameter of 2 to 3.5 m, which renders it more fine into slurry, with a water content ranging from 35 to 40%. (UNIDO, 1994).
The slurry manufactured in the previous stage, in inserted in a washmill - storage tank with a capacity of several hundred tons, in order to be homogenized with the corrective materials, where the clay is pulverized (mixed further to a paste) in the presence of water.
The cement industry of India is predictable to add 30-40 million tonnes per annum (MTPA) of capacity in 2013. The industry has a present capability of 324 MTPA and operates at 75% to 80% utilization.
Crushed lime is then added and the whole mixture is further ground. Any material which is too coarse is extracted and reground. The mixture resulting from the aforementioned procedure is further mixed in order to make the ingredients uniform and sent for clinker burning to a rotary kiln (UNIDO, 1994).
Though the installed capacity is 20.0 mn MT, currently the actual capacity is about 13.96 mn MT due to supply constraints for power and clinkers.
The produced slurry has to undergo certain tests, in order to ensure that it contains the correct balance of minerals, and any additional ingredients are blended in as necessary (NZIC, 1998). In other respects, the two processes are essentially alike (PCA, 2013).
The government of India gives grown to different infrastructure projects, home services and road network. The cement industry in India is presently increasing at an enviable pace. Other growth in the Indian cement industry is
predictable in the future years. It is also predict that the cement production in India would go up to 236.16 MT in 2011. It is also predictable to go up to 262.61 MT in 2012.
According to UNIDO, (1994), in the wet process, the slurry can be easily mixed, but a significant amount of energy is consumed due to water evaporation in the clinker burning. The dry process consumes less energy and its running cost is lower, while on the other hand, the plant construction cost for wet processing, is relatively low and high-quality products are easier to manufacture.
Urbanization and demand for accommodation are increasing day by day. Thus it is expected that the real sector will grow steadily with the household users‟ increasing cement consumption pattern.
According to the New Zealand’s Institute of chemistry (2008), the dry process uses more energy in grinding but less in the kiln and the wet process has lower overheads than the dry process. However, while the differences in quality
between products from the above processes are eliminated by the progress of technology, the needs for energy conservation are getting increasingly strong nowadays.
In the year 2001 - 2002 the 3.38 millionterrn, in the year 2003 & 2004t is 3.36 milliontern exported from india. In 2001-2002 1.76 million tons of clinker exported from India. And In 2002- 2003 is around 3.45 mt clinker exports. so under the compare of above data this shows that the export of Indian cement position
increasing at a stable pace over the years. The Indian cement typically Export to the West Asian countries
. Export of Indian cement has been registered at a fair amount of growth.
It is expected that in the future, the wet process will be gradually abandoned (UNIDO, 1994).
& Panarese, 1988)
3. Raw Materials Data
Cement manufacture, is a production processes that is in fact initiated at the mine, where the raw materials such as limestone, silica, aluminates, feric minerals and others are obtained.
The largest 13 cement manufacturers hold 78% of the market share. Heidelberg, Holcim and Lafarge are the leaders among multinational cement manufacturers and Shah and Meghna are the leading domestic manufacturers. Shah cement is the market leader with close to 14.20% of the market share, closely followed by Heidelberg with about 9.30% of the market share. During the 2010, manyVsmall local manufacturers like Premier, Seven Circle, Crown, Fresh and King cement increased their sales drastically riding on their benefits of economies of scale, backward linkage and aggressive marketing Effort.
Typical materials used for the provision of calcium carbonate in cement manufacturing are limestone, chalks, marbles, marls, and oyster shell. The necessary alumina volumes for the cement manufacturing is provided be materials such as clay shale, slags, fly ash, bauxite, alumina process waste, and granite.
Cement production in India grow up at a rate of 9.1% during the year 2006 to 2007 against the total production of 147.8( MT) in the preceding year. During the year 2008 and 2009, the manufacture of cement in India is of 101.04(MT) . During the Oct-2009, the total cement production in India was 12.37(MT) compare to a production of 11.61 (MT) in the same month in the preceding year. The cement companies are increasing their productions owing to the high market demand. The cement companies see a net profit growth rate of 85%. With this more success.
Silica is provided by materials such as sand, shale, clay, claystone, slag, and fly ash. Other typical materials used in cement manufacturing for the provision of the iron needed, are iron ores, blast furnace flue dusts, pyrite clinker, mill scale, and fly ash (Mine-Engineeringcom, 2012).
Real estate developers and Govt. projects are the dominant users of cement. During 2007-2008 public sector construction works were slowed down under caretaker government. Unwillingness to disclose the source of income contributed to the downward trend in real estate sector, i.e., building of apartments, flats etc. during that time period.
Therefore, the main raw material to produce cement is a rock mixture of lime materials and clayey materials of which about 20% is clay or shale and the rest is limestone. The raw material for cement manufacture are quarried and stored separately.
The Australian Cement and Lime Manufacturing industry is make revenue at $2.6 billion in the year 2012-2013. Its manufacturers supply approximately 96 percent of the value of domestic demand, and which is currently shown as $2.71 billion.
Based on the above, it is evident that the most important raw material for the production of cement’s clinker is limestone (which is rich in CaCO3), that is surface mined in quarries near the cement plant.
Indian Cement industry was under the manage by the government. India fall in the of lowly per capita consumption list of cement with 125 kg. The reason behind is this the poor rural people which generally live in mud huts and cannot have enough money to have the commodity. In a quick developing economy
like India, there is always great option of expansion of cement industry
The availability of suitable raw materials is normally the determining factor in the location of cement works and these are normally located in close proximity to limestone deposits and ideally close by other major raw materials (clay and gypsum) (British Geological Survey, Mineral Profile, Natural Environment research council
On the flip side, some caution has to be maintained due to the current demand- supply gap leading to over capacity and falling margins and prices. Also, given the close linkages between them, the effect of a slowdown in real estate growth or hike in interest rates globally or price increase of imported raw materials should also be
This is due to the fact that since the raw materials (fractured limestone, argillaceous rocks, quartz stone, iron ore, bauxite) for the production of cement is of low value, in order to minimize the raw materials transportation cost, cement plants are sited close to sources of raw materials (especially near to the limestone quarries).
The Australian cement industry continuously increased the use of alternative fuels lower the industry’s greenhouse emission and also waste going to landfill. The use of alternative fuel sources such as use oil, demolition timber and solvent fuels has steady among 7% and 8% in the Australian cement industry
Since approximately 80% of the raw materials necessary in order to produce of clinker are calcareous, the necessity of cement production facilities neighbouring limestone mining units is more than obvious.
In the year 2011 the Indian production is 228 (mt) million turn.
This saves the transportation costs and therefore reduces the price of the cement.
While limestone is the primary calcareous raw material need for the production of clinker clay (argil) or shale (a source of silica, alumina and Fe2O3) must be added to the mixture. The main strength of the cement is provide by the lime and silica, while the use of iron reduces the reaction temperature and causes the characteristic grey color of the cement. The commonest calcareous raw materials for cement production as mentioned above are limestone and chalk, but others, such as coral or shell deposits, can be used as well. The lime that is needed for the production of clinker, is obtained from a calcareous (lime-containing) raw material, while the other oxides necessary are derived from an argillaceous (clayey) material. Additional raw materials such as silica sand, iron oxide (Fe2O3), and bauxite (containing hydrated aluminum, Al[OH]3) may be used in smaller quantities, in order to acquire the desired mixture composition (Encyclopaedia Britannica, 2007).
Australian supply chain newly extended with the addition of some new pressure tankers as well as they are looking for diversification in some locations. If you are a driver look to work in a constantly rising industry
, they encourage to consider us an exciting career option.
Clays or silts are preferred since they are already in a finely divided state, but shales, schists, and other argillaceous rocks are also used (ACI, 2001).
Since rock is the principal raw material for cement’s production, the first step after quarrying is the primary crushing which reduces the rock to a maximum size of about 6 inches.
Indian cement industry’s total turnover is expected at USD25 billion in 2011. In the Indian cement industry 3 main players are contributed about 97% of the installed capacity during 2011.
The crushed material is then processed by secondary crushers or hammer mills so it can be reduced to about 3 inches or smaller (PCA, 2013).
The world distribution of suitable for cement production raw materials is far from uniform (Bye, 1999). …
In order that sustainability of the cement is achieved various processes of the manufacturing process must be altered accordingly. The most evident way of achieving this is by going back to the basics of cement’s manufacturing and reducing the need of clinker production.
Reducing the amount of the cement clinker has two advantages.
Indian Cement Industry has see ups as well as downs. wherever its competitiveness and tendency to grow up for achieve a technically sound position has help in the industry seen an impressive increase in export.
It both reduces the consumption of natural non-renewable raw materials and the emissions of greenhouse gases. Cement produced by using 30% additives results to 230 kg or 27% reduction of CO2, than traditional cement produced without additives (Lafarge, 2013). Cement additives may be of natural origin, such as limestone and pozzolan, or of industrial origin
, such as wastes from other industries, namely, blast furnace slag from the steel industry, or fly ash from power plants burning coal. Alternative raw materials have hydraulic binding properties, and can replace the clinker under certain conditions. For example
, in Greece, Heracles cement plant adds fly ash and pozzolan in some of the bulk and bagged products (Lafarge, 2013). The ash is incorporated at about 70 - 80% in the clinker and affects the previously mentioned values of LSF and SR, so it must be taken into account when determining the supply ratio of the raw material (Tsakalakis, 2009).
Chittagong Cement (taken over by Heidelberg where the local brand is called Ruby)
3.2. Ways of extraction
The general mining methods used for cement’s raw material extraction are surface mining, while some silicates such as sand, are commonly mined using dredges from rivers, lakes and waterways. The majority of limestone mines are pits on the surface but there are a few underground as well.
In the Indian cement industry there are 139 big cement plants and more than 365 mini cement plants in India. Currently 42 players are there in Indian cement industry.
The methods of winning limestone are associated with its hardness. Soft marls and chucks after being scraped from the quarry face, they are crushed at the quarry site prior to their transportation to the cement plants blending facilities. Hard material requires blasting and one ore more stages of crashing before it is ground. Composition variations are accommodated by quarry faces adequately planned development
, using the available geological surveys and any additional composition trends, indicated by the regular chemical analysis of the
extracted material and by blending in a stockpile. Beneficiation process other than the rejection of inadequate material is quite rare, although is some occasions floatation is implemented (Bye, 1999). At the quarry, the raw materials are reduced to desired sizing by the use of primary and secondary mechanical crushers. The extracted material is first reduced to 125-mm (5-inch) size, then to 19 mm (3/4-inch) (PCA, 2013).
3.3 Participation of raw materials in the production chain
Approximately 1.5 tonnes of raw materials are required to produce 1 tonne of finished cement (Jankovic & Valery, 2004). Other sources such as the National Technical University of Athens (Tsakalakis, 2009), claim that in order to produce 1 tone of cement, approximately 1.6 to 1.65 tons of raw materials is required the majority of which consists of limestone. In Greece for example according to 2006 data 75% the raw material, i.e. 0.75x1.65 x 16.1 million tons (Annual production of the Greek cement industry) = 19.92 x 106 tons of limestone were used for cement production and also approximately 4 - 4.5 x 106 tons were non-calcareous rocks (aluminosilicate minerals, quartz sand, bauxite, pozzolans etc).
3.4. Final product generation methods
As mentioned above, there is a number of different types of cements for use in the building industry, including Portland, blended and hydraulic cements, which in Europe they are standardised to BS EN 197-1. The types of cement produced in each EU country depend on the availability of raw materials, as well as the demand for each cement type. Therefore various types of cements which can be produced according to the aforementioned local conditions have been developed. These types include the common Portland cement, or cements that contain in specific portions pozzolan, silica fume, blast furnace slag, fly ash (silica or limestone), limestone, etc.
The basic types of cement in use in the European Union (according to the European standard EN 197-1) are :
CEM I - Common Portland cement (comprising of Portland cement and up to 5% of minor additional constituents)
CEM II - Composite Portland cement (comprising of Portland cement and up to 35% of other single constituents)
CEM III - Blast Furnace cement (comprising of Portland cement and higher percentages of blastfurnace slag)
CEM IV - Pozzolanic cement (comprising of Portland cement and higher percentages of pozzolana)
CEM V - Composite cement (Comprising Portland cement and higher percentages of pozzolana and blast furnace slag or fly ash)
The main sub-components used in the production of composite cements according to the European standard EN 197-1, are given below with typical capital Latin letter to each of them:
S - Blastfurnace slag
D - Silica fume
P - Natural pozzolana
Q - Natural calcined pozzolana
V - Siliceous fly ash
W - Calcareous fly ash
L, LL - Limestone
T - Burnt shale
M - Two or more of the above
Clearly, due to mainly environmental reasons (reduction of emitted CO2, utilization of industrial by-products), much of European production relates to composite cements (CEM II).
To form a consistent product, it is essential during the raw material preparation process, the same or virtually identical mixture of minerals is used every time. For this reason the exact composition of the limestone clay and other necessary ingredients in the form of additives, has be determined at this point, according to the desired clinker characteristics.
4. Environmental impacts
The operation of cement factories and holistically the cement making process, often presents environmental problems at all stages of the procedure, since many of its aspects are potentially environmentally damaging, even though these risks can be minimised is adequate mitigation measures are foreseen. The areas of potential concern include emissions of airborne pollution in the form of dust, gases, noise and vibration when operating machinery and during blasting in quarries, and damage to countryside from quarrying (Wikipedia, 2013).
As it is evident by the cement’s production procedure discussed in previous paragraphs, cement manufacturing is quite energy intensive. This is attributed to the high temperature processing required for the creation of clinker. As with the majority of the industries that burn fossil fuels, the cement industry also generates great volumes of gaseous emissions and in minimal volumes other combustion by-products. The main consideration is the emissions during the manufacturing process, mainly CO2. In cases where coal is used for energy production for the cement factories, additional problems are caused, due to the generated large quantities of dust after the combustion process. Emitted CO2 quantities by the cement industry are quite significant and they are primarily attributed to the calcination phase of the manufacturing process (burning [breakdown] of limestone) and fossil fuels in the primary metallurgical process and secondarily to the burning of fossil fuels for electricity generation that is consumed in all phases of cement’s production.
In Indian per capita consumption of cement is about 156 kg, which is low in compared with the global average consumption of about 356 kg .
CO2 emissions reduction through increased energy efficiency is only possible on the latter of the CO2 emissions generation procedures. The cement industry invests in modern technology in order to gradually decrease the specific fuel consumption per tone of clinker, in parallel with a corresponding reduction in carbon dioxide emissions. In correlation to the above, exhaust gases trapping and at the same time separation by the use of specifically designed equipment is
coming into increased use (Wikipedia, 2013).
Small and midiumsize cement players have rising constantly their installed capacity to increase cement demand .
Another major environmental consideration for the cement industry is the large quantities of dust generated by the production of cement. It is understood that the pervious must be prevented from escaping to the atmosphere, both on environmental and economic grounds. The two areas where dust has the potential to escape are directly from equipment used to transport cement, such as the various conveyor belts and via air streams that have been used for carrying cement (eg. the mills or kiln) (NZIC, 1998).
The above poses a significant challenge to the manufacturing operation of cement plants both in monitoring of emissions and capital investments for reducing the generated emissions, in order to ensure the full compliance with the limits foreseen by the legislation that is today into effect in each cement producing country, or may be imposed in the future. In recent years, dust emission limits exceedances of the cement industry have been minimized due to the implementation of modern methods, procedures and equipment, in synergy with the adoption of stricter legislation, but we are still far away from declaring the existing condition as idealistic. In order to prevent dust emissions, all transport equipment must be enclosed and the air both from these enclosures and from the mills and kiln should be treated in an electrostatic precipitator, so that the load of dust is removed (NZIC, 1998). Worldwide such adequate equipment is widely used in order that dust emissions are reduce during both at raw material quarrying and the cement manufacturing process
Furthermore, due to the nature of the cement industry, it consumes large volumes of energy and natural resources. The estimate for the energy consumption worldwide for the production of cement is 18.7 TWh, which is approximately 0.02% of the total world energy consumption per year (Jankovic & Valery, 2004). According to the same source, the electrical energy consumed in the cement making process is in order of 110 kWh/tonne of which 30% is used for the preparation of the raw materials and about 40% for the final cement production, by grinding the clinker in order to produce cement. In order to moderate the associated energy needs for heat, the heated exhaust gases from the clinker burning process, are often used to raise the temperature of the incoming raw feed, in special heat exchangers called preheaters (ACI, 2001). As with the majority of minerals used as raw materials, fossil fuels used for energy generation for the cement industry, comes from non-renewable resources, which in conjunction with the building industry expansion recorded the last few decades around the globe, imposes significant environmental considerations concerning the sustainability of the industry.
In the f.y 2012 cement industry record a turnover of a$2.15 billion and employed over 1,700 people, many of whom are base in Australian regional area.
Taking to consideration all the above, in order to achieve reduction and even elimination, of the production and release to the environment of greenhouse gasses and damaging pollutants, particularly CO2, by the cement industry, a "green shift" must be implemented, namely by the form of a "greener" cement. It is well established that in order to achieve such a shift and one of the main ways of producing cements with a lower carbon footprint, is by recycling materials that are used as additives to the cement. As "Green Cement" we define "the cementitious material that meets or exceeds the functional performance capabilities of ordinary Portland cement, by incorporating and optimizing recycled materials, thereby reducing consumption of natural raw materials, water, and energy, resulting in a more sustainable construction material" (Wikipedia, 2013). A concrete and viable way to shift to "Greener" cement, is with the widely adopted use of additives in cement’s production, which not only enhances certain cement properties, but at the same time it recycles materials that would otherwise have been sent to landfills, reduces the consumption of natural raw materials, and reduces CO2 emissions.
Another problem for almost all quarry operations therefore cement raw material extraction processes as well, is the treatment of waste water from quarrying procedures and storm water runoff. It is common that these effluents are trapped in wetland areas, where they are treated in an adequate and controlled manner. Within the factory, runoff can be contaminated by oils, lubricants and other chemical factors. In order that relevant considerations to the previous are addressed, the runoff is monitored and the plants have to establish regular training programmes to ensure this does not happen, or in case it can not be avoided appropriate mitigation measures have to implement.
Incorporating environmental sensitivity to the general operational framework, decision-making and adopting it as a fundamental parameter and business priority for the cement industry is deemed essential in order that the cement producing facilities around the globe, achieve the sustainability of this industry sector. In order to achieve sustainable development, the cement industry must balance environmental protection, social needs and economic issues. For example re-integration of quarries into the countryside after they have been closed down by returning them to nature or re-cultivating them is another integral part of the environmental protection, that must be foreseen by the cement industry (Wikipedia, 2013). In the direction of mitigating or ever completely resolving in some cases the environmental considerations associated with the cement industry, and correlation with the aforementioned necessity of achieving the sustainability of the sector, the following actions should be considered by the cement producing firms (HCIA, 2002):
Constantly seek to reduce air pollution from their plant’s operation, using modern pollution control technologies (electrostatic precipitators and bag filters) by optimizing the operating conditions.
Participate in the international effort to combat climate change by reducing carbon dioxide emissions, the main contributor for global warming.
Positively contribute to the national efforts of waste management, by exploiting residues or byproducts of other processes as alternative raw materials (fly ash, slag etc) and alternative fuels (tires, etc), in synergy with reducing the use of non-renewable natural resources.
Gradually control and reduce the energy and water consumption.
Continuously seek to improve their environmental performance and implement environmental management systems.
Offer modern processing systems of any personnel waste flow.
Take measures to protect the marine environment during cement and raw materials loading and transport.
Conduct extensive and consistent restoration of quarry sites through land rehabilitation and tree planting, while at the same time improves the aesthetic appearance of all the production units.
Educate and sensitize their employees on environmental protection issues.
Being open to communication and collaboration with all stakeholders (authorities, agencies, local communities, etc).