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March 2008

Sustainable Growth

M.K. Singhi, P.K. Tripathy, R. Bhargava and Ashok Tambi, Shree Cement, India.

Shree Cement is aiming to reach 20 million t capacity by 2012 and also aims to achieve 10 million tpa capacity by the end of 2008, by building two greenfield projects: Line 3 and 4, with a capacity of 1.2 million tpa at Ras in the Pali district of Rajasthan. This article discusses the upgrading of the company's existing plants and the development of the two new greenfield projects in an attempt to create higher capacity, and at the same time, maintain an environmentally sustainable organisation.

Fast-Track Expansion

Mohammed Ahmed Al Dheed, and Tapash Chakraborty, Raysut Cement, Oman

Raysut Cement Co. successfully commissioned its 1500 tpd line 2 in 1998. The line's production capacity has since increased to 1750 tpd. This was followed by the commissioning of a third production line in 2005. Line 3 began with a production capacity of 3000 tpd, and this has since increased to 3300 tpd. Since the commissioning of line 3, market demand has grown further, and the company looked at strategies to meet the surge in the shortest possible time with reasonable investment costs. The decision was made to construct a fourth production line by adding a new 2000 tpd pyroprocessing line, as well as upgrading the existing line 1 raw mill and cement mill. With the addition of the new line, the company's total annual cement production will increase to 3 million tpa.

Increased Capacity at Vicat

Yves Keller, Industrial Director, Vicat, Turkey

This article provides details of two recent upgrade projects in the Turkey. Firsly, the Ba_ta_ plant in Elmada_ where, at the end of 2005, the decision was taken to invest in a new 4000 tpd clinker production line. Erection is currently underway here and commissioning is scheduled for next September; and secondly the Konya Plant, where, since 1991, the plant's clinker capacity has been increased step-by-step from under 600 000 tpa in 1991, to 5000 tpd, after the construction of a new kiln in 2000.

Coal Mill Systems

Lars Bastue, FLSmidth, Denmark.

During the last decade, a large number of existing cement plants have been converted from oil to coal firing, and new cement plants have been arranged for coal firing. Coal is normally the cheapest fuel and the growing interest in coal firing has been brought about by the increase in gas and oil prices. This article discusses the factors involved in the use of coal mills in cement plants.

Calcining Technologies for

Alfred Brosig, Grenzebach BSH GmbH, Germany.

Over the last three decades, the use of different raw gypsums has varied. The 1970s was the peak period for installing phosphogypsum calcining plants in Europe, whereas to Asia, most equipment was supplied in the 1990s. The environmental legislation on desulfurising coal fired power plants initiated in Germany and other European countries, led to a demand for calcining FGD gypsum. A large number of plants have been supplied since the mid-1980s. The developments of calcining technologies for the different raw gypsum sources for manufacturing stucco (Beta-Hemihydrate) are discussed in this article. Stucco is the main intermediate material for the widest variety of gypsum products.

A Palletless Solution

Dieter Reitemeyer, on behalf of Maschinenfabrik Mšllers, Germany

In the palletless wrapped despatch unit, the pallet is replaced by the palletised product itself and a small amount of the PE-shrinking film that is usually used to secure bags to the pallet. This saves considerable costs for the purchase of the pallets, as well as for repairs, transport, storage and the administration of the pallet stock. The hermetically tight shrunk package cover holds humidity and any pollutions far from the bagged cement. This is an additional benefit: the package can be stored in the open without the quality of the cement being endangered; storage space can be saved; the packages can be transported on open vehicles. Palletless shrink wrapping was found to be the ideal solution for the Perak Hanjoong Simen plant in the north of Malaysia, and this article presents a case study of this project.

Dust Collectors: Design and Troubleshooting

Andy Winston, Global Cement Industry Manager, GE Energy, and Andrew Hollinghead, Senior Consultant, Penta Engineering, USA.

In order to operate and maintain equipment properly, it is important to look at one's dust collection equipment as part of a complete system. The Portland Cement Association has offered a dust collector class in several locations in the United States over the last few years and this article is an abbreviated version of the information that is covered in the eight-hour session. The authors of this article offer advice on how to improve the performance of dust collection equipment.

Reliable Protection

Wolfgang Leichnitz, Kalenborn, Germany

Modern industrial production requires continuous, trouble-free plant operation, particularly with respects to reducing capital spending, minimising maintenance efforts, and appropriately assigning manpower. This applies to industry in general, but has particular relevance for the cement industry. All transport and storage systems at cement plants handle large quantities of abrasive bulk materials; successful plant operation therefore relies on the proper design and protection of the various conveying units. This article discusses some current advances in wear protection technology, which can enable the economic operation of any industrial plant, but especially cement production facilities.

Online Stockpile Analysis

Darrell Leetham, Thermo Fisher Scientific, USA

As the cement market becomes increasingly competitive, producers continually seek means to increase production efficiency, reduce costs, and optimise product quality. In order to achieve this, plants much actively implement updated technology and improved processes. Mitsubishi's Lucerne Valley plant is located at the base of the San Bernadino Mountains and supplies the southern Californian market is one plant that has seen multiple modernisations since its construction in 1957. This article discusses the implementation of the most recent of these, an upgrade of the stockpile preblend process with an online analysis system that makes use of high-frequency analysis ad quality control software to automatically blend quarried raw materials into the circular preblending storage pile.

At-line Particle Size Measurement

Stephanie Verhaeghe and Fabien Verscheure, Holcim, and Jim Scotland, Malvern Instruments

While on-line particle size analysis coupled with fully automated control is increasingly widespread within the cement industry, good control can also be achieved using automated at-line analysis. An automated lab brings the analytical process closer to production, simultaneously minimising the manpower associated with routine analysis. Technology has developed to the point where a fully automated laboratory operating 24/7, with minimal manual input, is an accessible reality. Analytical systems such as the Insitec ALISS are designed to operate within the process environment and integrate with existing control platforms, facilitating the use of data in automated control strategies. Here, the authors report on a recent upgrade at Holcim Obourg that saw the production plant move to an automated laboratory for the routine analysis of cement composition and particle size, and the role of Malvern's process systems in improving analytical efficiency and process control.

Safe and Simple

Dr Michael C. Mound, Business Development Manager, Spectraflow, ABB Switzerland Ltd

The management of competing constraints, while controlling costs and quality, represent conflicting demands on the cement manufacturer. Knowledge of chemical and mineralogical balances in each process stage has, until recently, only been possible using bulk analytical systems, containing radioactive materials and excitation sources. However, the increased desire for protection from hazardous consequences has resulted in delays in receiving authorisation permits for the use and possession of such materials. There is thus a requirement for safe analytical devices that deliver reliable, real-time results. The use of one such device - ABB's Solbas CM100 analyser, which utilises near infrared spectroscopy to supply chemical and molecular analysis - is the subject of this article.

Refractory Solutions

Maria Webb-Janich, Germany, Serge Lecointe, France, Jess Sun, Taiwan, and Mikael Berg, Sweden

Brick linings have widely been replaced by monolithic solutions in the cement industry. Much progress has been made through the development of innovative solutions such as LCC (low cement castables) and ULCC (ultra low cement castables) combined with modern installation technologies, such as self-flowing material, spraycasting and high compact gunning. This article describes how Calderys' solutions are driving improvements in the main wear zones of the cement unit and extending reliability and lifetime.

Overcoming an Alkali Problem

R. Mohebbi, M. Sadeghi, M. Miraghassi and A. K. Amereh of JDEVS, Iran

The Iranian cement industry has experienced an expansion boom in recent years, both in local markets and in exports to neighbouring countries. About two years ago, JDEVS, an Iranian air pollution control company, was invited to submit a proposal for a turnkey alkali bypass system on Qeshm Island, located in the Persian Gulf, south of Iran. JDEVS, the Iranian partner of FLS Airtech, designed and manufactured the entire system while FLS Airtech designed the required ESP. This article describes how the manufacture of the new system has resulted in the production of low alkali, high quality clinker in an extremely dry climate.

Cementing Romania's Future

Mihai Rohan, President, Romanian Cement Association (CIROM)

Following its accession to the European Union, Romania is committed to building a new Europe on enduring foundations. The country's cement industry will be an important pillar in securing the country's transformation. With high domestic demand and investment in the industry, its prospects look bright. This article provides a brief overview of the industry, including profiles of three major players that currently have a presence in the country.

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November 2006

• Moving Cement at Sea
  Ferruccio Conti, CONTIMPIANTI S.p.A., Italy.
  • Since October 2005, Turbocem, Italcimenti's first self-unloading cement carrier, has been able to dock at the new stocking and distribution terminal in the harbour at Genova, Italy. Contimpianti, which specialises in the design and realisation of bulk material extraction and loading devices, was selected to be the main supplier of the necessary facilities for extraction and loading at the terminal.
• Pushing the Limit
  Jeff Ouhl, Ste. Genevieve, Holcim (US) Inc., and Kevin Happ, FLSmidth Inc., USA.
  • Holcim is currently building a 12 000 tpd clinker production line along the Mississippi River in Ste Genevieve County, Missouri, USA. This massive greenfi eld plant will have an annual cement capacity of 4 million t, along with barge facilities in a newly constructed harbour. Holcim has chosen FLSmidth Inc. to supply all the main and auxiliary mechanical and electrical equipment, as well as engineering services, training and commissioning. The plant is designed to produce ASTM Type I/II low alkali clinker and cement (Na2Oeq less than 0.6) without the installation of a kiln bypass system and therefore no CKD (cement kiln dust) waste.
• Looking Back on a Good Year
  Adnan Ignebekcili, Turkish Cement Manufacturers' Association.
  • This article looks back at the developments in the Turkish cement industry in 2005. Negotiations for Turkey's entry into the EU began, and the economy improved in both domestic and international markets. The construction industry began to improve, spending the fi rst nine months of the year as the country's leading industry. Domestic sales in the cement industry reached their highest since 1998, and cement consumption per capita also increased. Turkey was in the top three major cementexporting countries in the world, despite the fact that total exports dropped slightly, probably due to the increase in domestic sales. Iraq remained the most important export market, with other important markets being Italy, USA and Portugal. Expectations for 2006 include increased investment in the industry, and a boost in cement sales of between 6 - 8%.
• Automated Testing
  Michael Morrisson and Charles Walden, CTLGroup, USA.
  • Advances in automation over the past ten years have allowed the typical cement laboratory to go high-tech. The use of micro-processors, computer programs, robotics and optics has permitted increased precision and accuracy in testing, as well as greater laboratory effi ciency. While cement-testing methodologies may vary throughout the world, the cement properties being evaluated remain largely unchanged. The use of automation to test these has been encouraged by changes in testing standards. The last decade has seen the inclusion of 'alternative methods' of testing that have offered the industry numerous opportunities for moving into the era of automated testing.
• Improving Quality and Control
  David Rapson and Peter Storer, FCT ACTech, Australia.
  • Maintaining consistent mineralogy has always been the objective of cement plant staff, typically by using regular laboratory tests. With advances in computer and analysis technology, it is now possible to measure many of the process streams around a plant in real-time in detail and at a frequency not previously possible. This article discusses how on-line XRD analysis using the FCT COSMA can be used to control clinker phases, free lime, gypsum and, ultimately, raw material composition.
• Trends of Blended Cement
  Shunsuke Hanehara, Iwate University Japan, and Kazuo Yamada and John Saunders, Taiheiyo Cement Corporation, Japan and UK.
  • Reflecting on the current situation in which the reliability of concrete structures is in question, the concept of a desirable cement to make durable, general use concrete, whilst at the same time considering environmental burden, is discussed. In this study of normal concrete of nominal strength 30 MPa using Japanese and European cements, European cement of lower strength class was comprehensively superior to the Japanese ordinary Portland cement (OPC). This is because the resistance to material segregation was improved by maintaining the necessary amount of cementitious material (powder). From an overall evaluation of various environmental burdens, OPC also contributes to reduced environmental burden by utilising waste materials and can further contribute to the environment by the production of blended cement.
• Missing a Trick
  Karsten Brink Floor, FLSmidth Inc. Automation Division/FLSmidth Airloq A/S, Denmark.
  • Less than a third of all cement plants worldwide have a successful kiln inlet gas analysis system capable of cashing in on the benefi ts it can bring. This article provides an account of why cement plants should utilise a kiln inlet gas analysis system and how it can optimise cement production. It emphasises that whilst no kiln inlet system will be maintenance free, the benefi ts of the system far outweigh the disadvantages. Typical payback for the KilnLoq gas analysis systems installed is 100 - 200 days. It provides a solution to enable operators to handle diffi cult process conditions in an effective manner, allowing them to have confi dence in the results and ensuring optimised utilisation of the gas analysis data provided.
• Fundamentals of Filter Design
  Antonio Semenza and Giorgio Radaelli, Redecam Group, Italy .
  • The bag filter is Redecam's core business and this article outlines the design criteria that the company has always defined as the three areas in which to optimise the quality of its filtration systems: fluid distribution inside the filters; dust tightness between the dusty and the clean parts of the fi lters, and efficiency in bag cleaning.
• Cement Plants Unwired
  William J Miller, MaCT, USA .
  • St Lawrence Cement in Maryland, USA, is the fi rst cement plant to install a broadband wireless mesh network as an alternative to running wire. The installation provides the communication infrastructure that is used to monitor energy usage, provide emergency telephone access via voice over I-P (VoIP), for HART device integration and remote maintenance. The wireless system makes use of Wave RelayTM, a multi-hop wireless mesh networking communication system, which provides sufficient bandwidth to provision other services that use Ethernet and TCP/IP. The plant currently uses wireless for monitoring the chain gas and material temperature, as well as to meet the state safety requirement that insists an emergency phone be placed in all elevators to provide communication during a power failure. The Wave RelayTM system is running successfully and economically.
• Relying on Lignite
  Aditya Sanghi, Sanghi Industries Ltd, India.
  • Sanghi Industres Limited has set up a 2.6 million tpa cement plant at Gujarat, India. This is the biggest single line plant in the country and the fi rst in the world to use lignite as its only fuel. Lignite was chosen due to local availability, process capability and the offer of superior technology. This article describes the advantages and disadvantages of relying on lignite, and also provides a detailed description of other notable aspects of the plant, which include its all-weather captive jetty, captive power plant, and multi-effect desalination plant. The company intends to expand its capacity in the future, both via the brown and greenfi eld routes, and further reduce costs by utilising a new thermal-based power plant able to produce cheap and reliable power.
• More Efficiency, Less Energy
  Jay Henderson and Dan Banyay, Robinson Industries, Inc., USA.
  • Plants that regulate fan airflow with mechanical controls, such as dampers, may be blowing their money away. Employing fixed speed motors in combination with dampers may be ineffi cient, in terms of energy consumption, if the regulation or restriction of airfl ow regularly exceeds 20% of design flow. Variable frequency drives (VFDs) are a more effi cient way of regulating airflow when greater air restrictions (>20%) or wide ranges of airfl ow are required. While mechanical methods are generally cheaper in upfront capital costs, VFDs may be cheaper in long-term energy costs, depending on the application. This article describes the various answers to airfl ow regulation problems and the selection criteria that should be used when deciding upon the most appropriate solution.
• New for Old
  Jurgen Bech Storgaard, FLSmidth Automation, Denmark.
  • Many existing FLSmidth Automation customers have asked if it could develop a driver to connect its system to ABB Master-Bus 300. They want the FLS ECS Control/Center to interface to their existing ABB communication network without having to replace the complete installation. The first driver installation took place at the Valderivas El Alto cement plant in Spain. The plant wanted to upgrade its control system for three production lines that are each controlled by either of the two ABB control systems.
• The Power of Two
  Thomas Hagglund, Wartsila, Finland.
  • Cement companies worldwide are discovering the business advantages of having their own independent power source onsite. This is especially true in countries and regions where local supplies and grid connections are unreliable or too expensive, or in remote locations far from traditional forms of power supply. In remote areas, reliable power is a critical factor in day-to-day operations as cement plants make excessive load demands of stringent voltage requirements and significant frequency variation. In the past year there has been a surge in demand for cement in Pakistan, and there are a number of projects there to increase production capacity through both expansion of existing cement works and new plants. With these developments there is a corresponding need for additional power to supply the new capacity - a demand that cannot be met by the national grid.
• Cost Savings for Cement Conveying
  John M. Bell and Michael F. Crawley, Macawber Engineering Inc., USA.
  • The manufacturing and handling processes for cement are among the most power-intensive of all industries. Considering the actual volume of cement handled every day in cement plants and the savings that could be achieved in this area, the cost of handling deserves more attention. A visit to any cement plant will reveal that the technology of cement handling is virtually unchanged since it was fi rst introduced more than 80 years ago. A radical review of the requirements of cement conveying is well overdue. Conveying by pipeline is a well-established method, but this article looks at the dense phase pneumatic conveying technology that has been developed to use the pipeline more effi ciently to transfer much more cement at lower velocities and with less power than using the older methods. Details of the technology are provided alongside statistics showing the potential savings and examples of the technology in use.

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March 2006

• An Expanding Economy
  M. K. Singhi and S.S. Khandelwal, Shree Cement Ltd, India.
  • The Indian economy in general, and the cement industry in particular, is witnessing high growth. Considering the present demand level of 126 million t (2004 – 05) and a CAGR of 8%, the Indian cement industry would require a capacity addition of about 60 million t over the next 5 years. Sustained rise in demand can accelerate cement prices, facilitating better profitability. The Indian cement market, therefore, looks attractive for investment.
• Surplus and Shortage: a Struggle for Balance
  Farid Fazal, DG Khan Cement Co. Ltd, Pakistan.
  • In Pakistan recently, demand was about 12 million t against a capacity of 18 million t. Today demand outstrips supply, and the industry is running at almost 100% capacity. New projects announced by the government, such as the construction of dams and motorways, have contributed to this sudden increase in demand, and new capacity is in the pipeline to keep up with these projects.
• An Alternative Solution
  Lars-André Tokheim, Norcem, Norway.
  • Norcem AS started utilising alternative fuels at its Brevik in 1987. In 2003, approximately 35% of alternative fuels were used in kiln 6. To allow for a more extensive utilisation of alternative fuels, it was decided to modify the kiln system by upgrading the calciner, installing a chlorine bypass and increasing the capacity of the fuel feeding system.
• Grinding Facilities for Mossines S.A.
  Luis Casas Escario and Manuel Ortiz Aguilar, Adrian Consultores, S.L., Spain.
  • In April 2004 the cement grinding and storage installation of Mossines S.A. in Sines, Portugal, started operating. The plant takes advantage of its advantageous location close to Sines harbour and provides a strategic point for cement export to the Portuguese islands. This installation was originally conceived, projected, developed and supervised by the Spanish engineering company, Adrian Consultores. This article describes the various sections of the plant and its main equipment and suppliers.
• Cooler Operation in UAE
  Tor Gautestad, Union Cement Company, UAE and Mirko Koehler, IKN GmbH, Germany.
  • The gradual increase in cement demand in the UAE required higher clinker outputs from Union Cement Company (UCC). Part of the necessary plant improvements was the upgrading of kiln line 3. The capacity of this line was increased and the existing conventional clinker cooler became the bottleneck of the pyro line. To overcome this, and to further increase capacity, UCC decided to replace the clinker cooler with an IKN Pendulum Cooler, which was to be installed in the existing housing. IKN’s design work had to focus on fitting the pendulum grate into the limits of the existing cooler housing without moving the discharge point to the clinker conveyor. The new cooler is performing well with 99.99% availability, reduced maintenance costs and decreased dust emissions.
• Chlorine Bypass
  Luca Danuvola, Holcim Italia S.p.A. and Wolfgang Freimann, A TEC Advanced Process Technologies GmbH, Austria.
  • The objective of the Ternate plant was to increase use of alternative fuels to significantly reduce fossil fuel consumption. The continuous increase of alternative fuel consumption in recent years has led to a considerable increase of chlorine input into the kiln system. This caused a variety of problems, including reduced lining lifetime. To avoid these problems A TEC Advanced Process Technologies GmbH developed a chlorine bypass system, which reduces the circulation of volatile components. The Ternate plant placed the order for a turnkey bypass solution, which was successfully completed in 2004. With the new installation, Ternate kiln has reached a thermal substitution rate of fossil energy above 30%, reducing chlorine content in hot meal by approximately 50%. Without bypass, thermal substitution rate with the same alternative fuel mix was limited to approximately 18%.
• Safety First
  Mark Yseboodt, Siemens AG, Belgium.
  • The risk of explosion is something that all cement plants must consider. Gas analysers can monitor CO content to help avoid explosions, but sometimes results cannot be obtained quick enough to take corrective action. Ideally, CO measurement should be fast and reliable, and this is where the new Laser Diode Spectrometer (LSD 6) comes into play. It measures a gas component such as CO as reliably as a traditional infrared gas analyser, but with a very fast reaction time, and it requires very low maintenance and no recalibration.
• Separator Technology
  Joe Yardi, Cement Australia, Australia.
  • In many industries, the classification of very fine particles is carried out in air rather than water to avoid problems with chemical reactions of particles with water. This also avoids the complication of separating ultra-fine particles from water and drying them. Air separators handle hundreds of millions of tonnes of solid particles annually, mainly in cement and steams coal grinding circuits. Air classification first became important in the latter part of the 19th century when tube mills were developed to produce large volumes of Portland cement, which had become a significant building material. The grinding process highlighted the need for the efficient separation of ultra-fine particles from mill discharge, and screens proved to be inadequate. The principle of operation used in the early machines is still used in modern air separators. Their evolution during 100 years into second and third generation separators was to improve rejection of coarse materials and minimise bypass.
• Addressing Cement Shortages
  Earl D. Smith, Grace Construction Products, W. R. Grace & Co., USA.
  • This article examines solutions to the shortfall between domestic cement production and the current demand for cement in North America. It is suggested that all equipment should be well maintained to optimise the finished mill output. Furthermore, it is possible to increase production by decreasing the surface area of the product. This results in strength losses that can be made up by the addition of Quality Improver additives, which are designed to influence cement performance while at the same time acting as traditional grinding aids. Quality Improver technology can be used to maximise clinker replacement with limestone, to maximise kiln outputs and to facilitate the use of imported clinker. The article concludes that to reduce the gap between supply and demand, this technology should first be used to maximise domestic output, and when there is no alternative but to import, clinker should be imported before cement.
• Refractory Corrosion
  M.R. Saeri and M.R. Nilforoushan, University of Shahreh-Kord, Iran.
  • In this study, first the general aspects of corrosion and oxidation-reduction of ceramics were reviewed and then the corrosion phenomenon of a magnesia chrome refractory of a rotary kiln was analysed. For this proposal, the surface and the cross-sections of a corroded refractory were analysed with SEM and WDX methods. The results showed that the observed amounts of MgO values decrease on the surface after corrosion. Furthermore, after the surface of the refractory was dissolved, a few cracks were observed in the refractory surface. Generally, the results confirm that the microstructural control of the refractory is beneficial to decreasing degradation of the ceramic, and that this physically stable coating is suitable for long-term application.
• Blasting Through
  Wolfgang Zimmer, VSR-Industrietechnik, Germany.
  • Air blasters are proven and reliable helpers for bulk goods technology. In hot areas, for example cement production using derived fuels, they have become almost indispensable. Together with silo and bunker units, they form a reliable, long-lasting and beneficial partnership. Air blasters also help to reduce or avoid hazardous manual work, increase production and product quality, and reduce operational malfunctions and the associated costs. The advice of an expert in the planning and installation of an air blaster unit is indispensable.
• Ultrasonic Technology
  SOR Inc, USA.
  • When St Lawrence Cement, a cement production and packaging facility in Catskill, New York, USA, decide to upgrade its silo-filling operation in 2002, plans called for the installation of continuous level sensors to monitor the level of material and prevent overfilling. After conducting a head-to-head test of a radar unit and an ultrasonic unit, the plant chose to use the SOR echOsonixtm ultrasonic continuous level transmitter, which works even in extremely dusty conditions. This unit enabled the plant to achieve continuous and accurate measurement.
• The Final Analysis
  Tim Wilkes and James Hobby, Servomex Group Limited
  • Gas analysis is an important aspect of cement production. In theory, the gases commonly measured during cement production processes can be measured by a variety of commercially available methods. However, in practice, the number of techniques that can be safely, reliably and cost-effectively used is somewhat more limited. Purchasers, specifiers and users may have different drivers, so it is important to completely evaluate the specific application and whether a particular technique or manufacturer’s reference list is appropriate to that application. An analysis of long-term running costs and inherent reliability is also recommended, as the initial benefit of lower priced equipment based on simpler measurement technology can easily be offset by plant downtime, maintenance, calibration and environmental non-compliance issues further down the road.

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November 2005

• Expanding to Meet Demand
  Duane Crutchfield and Jeff Peterson, Ash Grove Cement, and Lars Hansen, Solios Environment, USA
  • Ash Grove Cement's Leamington plant in Utah, USA, was built in the late 1970s. The original kiln/mill baghouse and fan system required modernising in order to increase production, reduce power consumption, reduce maintenance requirements, lower outlet emissions and accurately monitor emissions. Solios Environment installed a TGT Filter, which is guaranteed to provide long life and low outlet emissions. Fabrication took place locally and the replacement baghouse and ancillary equipment was installed during the annual shutdown in April 2004, although a great deal of work was undertaken before the shutdown. The installation was a complete success.
• Increasing Capacity at Gulf Cement
  Ahmed Al Amash, Gulf Cement Company, UAE
  • Gulf Cement Company, one of the leading cement manufacturers in the United Arab Emirates, has decided to expand its clinker production capacity by adding another line to its existing production line. The existing capacity of the plant is 1.25 million tpa, and the new capacity will be 3.75 million tpa. In May 2004, an order was signed with ThyssenKrupp Industries India Pvt. Ltd, India, and Polysus AG, Germany, for the design, engineering, supply of main equipment and commissioning. The plant is scheduled to be commissioned in May 2006.
• Upgrades for a Sustainable Future
  Paolo Bianchi, Buzzi Unicem, Italy.
  • In the last three years the Buzzi Unicem Group has invested over E100 million in upgrading its plants. Recent projects have addressed the need to maximise production efficiency, meet growing market demands, and increase competition levels. Environmental and social sustainability are important to the company. The use of secondary fuels and receiving the Environmental Product Declaration at the Vernasca plant at the end of 2004 are testament to the long term vision and policy for this Italian company.
• Air Atomising Spray Technology
  Dave Foley, Vice President, Spraying Systems Co., AutoJet Technologies Division, USA
  • When the Zhejiang Guangyu Group planned to open a new cement mill, the company researched the latest gas cooling technologies to ensure that the new facility would be energy efficient and meet a high standard of environmental protection. A low-maintenance, low-energy system that uses air atomising nozzles was selected. Air atomisers benefit from a smaller drop size, which enables a more complete reaction and total absorption without wetting, as well as a large maximum free passage to reduce clogging, fewer nozzles, and smaller cooling towers.
• Improved Grinding Operations
  Al Popp, St. Lawrence Cement, (US division)
  • St Lawrence Cement, a New Jersey-based company, constructed a new plant to produce granulated ground blastfurnace slag, which became operational in 2001. Problems arose with an unstable material bed, which had a direct impact on the production rate, and worn tyres and table liners, which broke in June 2003. It was found that the best solution was to maintain the profiles of the tyres and the table liners by rebuilding them with weld overlay, and to improve the efficiency of the mill airflow to minimise overgrinding. The plant was modified during the winter maintenance shutdown in February 2004. Overgrinding has been greatly reduced, specific power consumption and specific thermal consumption is much lower and the mill now operates with a stable grinding bed.
• Efficient and Exchangeable
  Dr.-Ing. Caroline Hackländer-Woywadt, Loesche GmbH, Germany
  • Vertical roller mills (VRM) are commonly used for cement and slag grinding. They do not overgrind product and are highly energy efficient. If a plant has a raw mill and a cement mill that are served from the same spare part stock, then it is possible to save costs by sharing or exchanging parts. The VRM offers high flexibility and availability in a simple and compact layout.
• Double Roller Success
  Pietro de Michieli, Bedeschi S.p.A., Italy
  • The two toothed rollers of Bedeschi's double roller crusher turn in opposite directions and the speed can be differential. This processing system is highly effective at crushing any type of raw material, whether hard, soft, sticky or wet. The double roller crusher produces a low quantity of fines and a high quantity of 20 - 60 mm product, assuring the best efficiency for the downstream mill. Bedeschi received an order from Nasice Cement in Croatia to supply a crushing system for limestone and clay. The challenge was to design and install a crushing system capable of processing abrasive materials with high moisture content. The machines were commissioned in February 2005 and have been very successful.
• A New Arrival
  Matthias Mersmann, KHD Humboldt Wedag, Germany
  • The new KHD PYROFLOOR® clinker cooler accomplishes clinker conveying by the 'walking floor' principle, and controls aeration by self-regulating valves. For the application of the walking floor-principle in a clinker cooler, the design had to be engineered as a cassette-type aeration floor, in which the passive clinker layer serves as autogenous wear-protection and facilitates air distribution. The PYROFLOOR® utilises contact seals and a new type of flow regulator, which keeps the airflow constant. The cooler meets the client's requirements for an economic and low-maintenance solution to the conveying and cooling of cement clinker.
• Gravimetric Feeding Technology
  Dr. Hubert Wolfschaffner, Pfister GmbH, Germany
  • Gravimetric feeding technology is an important element in the cement industry's struggle to reduce costs, increase output and achieve a high standard of product quality. The rotor weighfeeder was designed with the knowledge of previous weighfeeder problems and advantages in mind, so that it offers a greatly improved performance. A unique feature of the device is that raw meal is fed directly from the weighfeeder into the process. Another important element of this system is its principle of prospective control, which can detect faults in advance so that they can be corrected when the material is transferred to the process, and also its control range, which greatly improves short-term accuracy compared with previous feeding systems.
• Monitoring Pyroprocess Lines
  Maurice Idoux, HGH Systèmes Infrarouges, France
  • Non-contact temperature monitoring for pyroprocess of cement manufacturing is a new and efficient system that offers lower down-time and higher productivity. It incorporates an infrared line scanner for kiln shell temperature monitoring, a kiln hood pyrometric camera, and temperature monitoring assembly for the clinker grate cooler. Together these produce a reliable kiln evaluation that can, through the swift detection of problems, save time and money.
• Improving Integration
  Klaus-Dieter Schreiter, Siemens AG, Germany
  • The cement industry is constantly facing tension caused by the need for optimum quality yet lower costs, as well as the need for long term investment versus the latest technology. Whether this affects the owner of a plant, a system integrator or a machinery supplier, the solution to the problem is always totally integrated automation. The worlds of automation and power engineering merge into one comprehensive and modular solution for a plant, incorporating specific services across the entire life cycle. The availability, therefore, of Totally Integrated Automation (TIA) and Totally Integrated PowerTM (TIP), as well as a comprehensive knowledge of the cement industry, must always be the basis for any decision about an investment in a cement plant.
• Making Use of Limestone
  M M Ali, S K Agarwal and K Mohan, National Council for Cement and Building Materials (NCB), India
  • The manufacture of Portland cement in modern plants often allows little variation in the quality of kiln feed, so that a considerable amount of limestone samples are frequently rejected at mining sites as overburden due to high MgO and SiO2 contents. The mix design and the kiln feed for each plant are considered as key to a successful and profitable operation. This article investigates the feasibility of utilising low-grade limestone, along with cement grade limestone.
• Zero Waste
  Michel Gimenez, Catherine Bouillon, Frédérique Ferey and François Sorrentino, Lafarge, France
  • Treatment of steel-making slags, EAF dusts, flyash and car shredder residue under reducing conditions by means of an electric arc furnace (Zero Waste process) produces a mineral having the same chemical composition as an industrial blastfurnace slag. Lafarge have experimented on this artificial slag and have discovered that it can be used as cementitious replacement.
• Real Time Analysis
  Peter Storer and Constantino G Manias, FCT International, Australia
  • Cement and clinker production is concerned with producing a precisely controlled blend of minerals with specific physical properties. There is now a method that directly measures these minerals. The method uses the COSMA - Continuous On-Stream Mineral Analyzer, which in turn uses state-of-the-art X-ray diffraction (XRD) techniques to directly measure the mineralogical composition of cement and clinker in real time. This new equipment gives a cement operator vital information and insight in real-time into the quality of the product during the various processing stages of cement production. Real-time analysis allows continuous online real-time and automated product quality control.

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March 2005

• Improvements at Mojave
  Bruce Shafer, Plant Manager, California Portland Cement Co., USA.
  • The Mojave cement plant is equipped with a four-stage preheater in–line calciner kiln operation. California Portland Cement Co, in an effort to improve clinker production, has introduced pure oxygen from two onsite vacuum swing adsorption facilities. The improvement in kiln operation led to further modifications, the first being the installation of an IKN KIDS system in the standard grate cooler, and the second, currently under way, will see the installation of a vertical roller mill for finish grinding. It was concluded that the fixed inlet is the unanimous choice in new cooler technology, and it is also an excellent retrofit option for existing reciprocating grate coolers.
• Fast Track Expansion in Costa Rica
  Holcim Costa Rica.
  • Cement consumption per capita in Costa Rica is approximately 300 kg with total cement consumption reaching approximately 1.2 million tpa. During the past 15 years the cement market has shown an average annual growth of 5%, and over the next five years average growth is expected to be 4% due to public works motorway projects.
    The modernisation of the cement plant, which is located approximately 26 km east of the capital of San Jose, began as an answer to the demands of the local and international market, as well as the desire to improve environmental and operational conditions, and to allow the use of alternative fuels in increased percentage levels.
• Overland Conveying
  Ferruccio Conti, Contimpianti, Italy.
  • The multinational cement company, BuzziUnicem, placed an order with the Italian company, Contimpianti for the supply and assembly of a conveyor belt which needed to cross over private land, and rights of way, with different existing services, as well as technological/environmental exigencies. After a careful survey, Contimpianti opted for a Vackem type belt which allows special bending radii with moderate sizes to be achieved, with performances equal to those of a traditional belt.
• Alternative Materials
  Javed I Bhatty and John Gajda, Construction Technology Laboratories,Inc (CTL), USA.
  • The cement industry has made use of numerous wastes and byproducts as raw feed components while tracking the economic, operational, and environmental ramifications to cement manufacturing. The composition of these materials must be compatible with those of the raw materials they replace in the cement raw mix. Materials so far identified as raw material components include marginal limestone, lime-bearing carbonates, sludges, mettallurgical slags, flyash, bottom ash, desulphurisation sludge from coal-fired power plants, mine and mineral wastes, catalyst fines and foundry sand.
• The Use of Petcoke as an Alternative
  V.K. Batra, Kamal Kumar and P.N. Chhangani, Holtec Consulting Private Ltd, India.
  • Petcoke is a byproduct of the oil refining cracking process where oil is subjected to extreme cracking, and virtually all the liquid phases are driven off to produce a residual product consisting mainly of carbon. The use of petcoke as an alternative fuel in a cement plant is feasible in most cases. The critical factor to decide the level of substitution with petcoke is the molar ratio of alkali oxides to sulfur oxides in the clinker.
    By comparison with coal, petcoke is categorised as a material with low volatile, very low ash content, high fixed carbon content and high sulfur content. Effective use of petcoke calls for design changes in certain pieces of equipment such as the grinding system, calciner and burners.
• Kiln Systems Upgrade
  Rune Damborg Hurttia and Kent Ege Jensen, L.V.Technology Public Company Limited, Thailand.
  • In the year 2000, L.V. Technology introduced a new cyclone design (LVC), which has been successfully installed in more than 15 installations. The new cyclone is a high efficiency one which reduces pressure loss considerably and thereby effects a reduction in fan power consumption. This reduction in pressure drop can be used to increase kiln capacity when installed in preheaters.
    The company performs a wide range of plant modifications and has carried out modifications that include ball mills and vertical mills, as well as preheaters, kilns and coolers. For kiln system preheater modifications implemented to increase clinker production, the key words are pressure drop, reducing modifications, and obtaining proper combustion conditions in the calciner. The idea is to reuse the existing ID fan, where the reduced pressure drop over the preheater opens up for increased flow, i.e., increased clinker production.
• Refractory Damage
  Makoto Ono and Hisao Kozuka, Mino Ceramic Company, Ltd., Japan.
  • Basic bricks are used in the high temperature areas in a rotary kiln, such as the burning zone (where the cement feed reaches around 1450 ˚C), the transition zone and the cooling zone. Temperatures in these two latter zones are lower than those in the burning zone and the amount of liquid phase formed in the cement feed is small. Accordingly, the cement coating frequently sticks to or drops off the basic bricks in these zones. On the other hand, a cement coating stably adheres to the basic bricks in the burning zone, where the amount of liquid phase formed is sufficient. Atmospheric and thermal conditions vary according to position in a kiln. The wearing mechanism of the refractory bricks varies in a similar manner. Refractory bricks are worn by the synergistic effect of thermal, chemical and mechanical actions.
• Refractory Steels: AFs and Corrosion Problems
  Alejandro Corcuera, Aceros y Suministros, S.A., Spain.
  • Over the past few years tests have been carried out in industrial environments on grades of steel which were developed for use in the presence of high concentrations of chlorine and sulfur. For the latest tests two new grades of steel were used. One was a 22.5.3 ferritic-austenitic duplex steel which combined high corrosion resistance under tension in the presence of sulfides with a good resistance to rusting and corrosion. The other steel was a GX30crNiSiNb 24.24 austenitic steel which exhibits strong resistance to rusting at high temperatures. The results obtained from the tests proved to be very good, but further studies will have to be conducted to determine how the materials will perform over time.
• Predicting and Preventing Machine Wear
  Dr Joanna Wolske, PANalytical B.V.
  • The ability of X-ray fluorescence spectroscopy (XRF) to measure trace metal concentrations with a high degree of accuracy and precision over a wide dynamic range in a single sample preparation, makes it a powerful tool for the analysis of wear metals in lubricating oils. For a typical high- power wavelength-dispersive X-ray fluorescence (WDXRF) spectrometer configured for oil analysis, the average lower limits of detection are well below 1 ppm for most of the elements relevant to wear metal analysis. But accurate quantification so close to the limits of detection necessitates spectrally clean net peak intensities, accurate corrections for inter-element matrix effects and good standards.
• Modern Filter Techniques
  Theo Schrooten, Intensiv-Filter GmbH, Germany.
  • Filtering separators are becoming increasingly important with regard to the separation of dust particles and other pollutants. They replace ESPs which cannot be retrofitted economically. This development is accelerated by the use of secondary combustibles such as waste oil, used tyres, domestic waste and organic residuals in rotary kilns. The filter media being used are generally tubular shaped needle felts which are stabilised by supporting cages. They separate the exhaust gas from the clean gas area. Most of the fibres, e.g., polyester, polyacrylnitrile, polyphenylene sulfide, meta-aramide and polytetrafluorethylene can also be provided as fine fibres or membranes. They can be processed to filter media with an almost pure surface filtration.
• Pleated Filter Solution Success
  Andy Winston, GE Energy, USA.
  • Pleated filter elements have proved to be beneficial in applications throughout the entire cement process, from the clinker cooler baghouse to the auxiliary units. The ease of installation and maintenance, reliability in performance, and extended filter life are just a few of the benefits of this versatile filter technology. For example, in a mid-western US cement plant they were used to help solve emission problems after an existing clinker cooler fabric filter dust collector had been found to be undersized.
• Analysis and Design of Silo Walls
  D. Lippold, Peter und Lochner, Germany, and J. Harder, OneStone Consulting Group GmbH, Germany.
  • It has been shown that the silo discharge system has a considerable influence on the size and eccentricity of the flow channel formation and the resulting wall loads in silos with a central cone. Depending on the discharge system, the number of aeration sections and discharge quantities, critical cases can occur with regard to wall loads. Generally, such critical cases should undergo an extensive analysis that includes the ideas presented. If it is decided that the case must be considered critical, post-tensioning in a circumferential direction may be a solution.
• Mix Design From Quarry to Cement
  Henrik Weisberg Andersen and Steen Tokkesdal Pedersen, F.L.Smidth Automation, Denmark.
  • The new QCX/BlendDesigner application module is the quality manager’s toolbox for mix design from quarry to cement. It provides guidance on how to produce a new cement type, minimise the cost of raw materials, and examine the impact of new raw materials, additives, dust, and fuel.
    It has been developed using the Microsoft .NET platform. It is browser-based and may, therefore, be distributed via the local area network, the intranet or even the internet, without the need to install QCX client software. Without a tool like this, the alternative is time consuming manual operations in a spreadsheet. Such a spreadsheet would not offer features like on-the-spot transfer of the currently applied control set up into the simulation data base, from where an imminent quality problem can be investigated immediately.
• Raw Meal Analysis and Control
  Adhi Narayanan, CemPro Analytics Ltd, Canada, and Reiner Hoenig, APC GmbH, Germany.
  • The SOLAS (Schnell Online Analytische Systeme) technology from APC, Germany, has been successfully used in the coal industry for the past 15 years. Results of off-line tests conducted with samples taken from various cement plants and fed manually to SOLAS helped to establish that SOLAS could be used for raw mix analysis and control in a cement plant. Tests were carried out at HeidelbergCement’s Lengfurt plant in Germany, and an analysis of the trials demonstrated the ease of installation and flexibility of integration with existing processes.
• Pfister Moves into China
  • Pfister GmbH specialises in weighing and dosing technologies for the cement industry. At the end of last year it opened a production plant in China. The chosen site was Qingdao, the harbour city in the province of Shandong. The company’s first client installed a Pfister rotorweighfeeder in 1995, and in the years since the company’s clientile has grown steadily and since the year 2000 it has sold 400 units in the country.
• Improving Profitability
  Allison Riser, Cement Performance International (cpi) Ltd, England.
  • Technical personnel in cement manufacturing plants often find it difficult to focus and prioritise on the technical improvements which can reap the highest rewards from a profit perspective. The marriage between profit and technical excellence is not an easy path to negotiate. This is why, as well as having a logical process, it is also important to have access to people with the relevant experience of successful implementation of profit improvement programmes. Historically, it has been very difficult to have a combined source of a logical process coupled with the relevant cement industry technical experience.

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November 2004

• Global Economic Trends
  Dr Norbert Walter, Chief Economist, Deutsche Bank Group, Germany.
• Since mid-2003 industrialised countries have been expanding at an average rate of close to 4%. World trade was up by nearly 7% in the first quarter of this year. In the G3 countries investment in machinery and equipment increased by 8.5% year on year during the first quarter of 2004.
  The global upswing was led by the United States and China with positive effects on Japan, while continental Europe continued to lag behind. The key question is the sustainability of the recovery in the near term and beyond. With rising oil prices and monetary and fiscal stimuli fading, the pace of world economic activity has shown signs of slowing down.
• Clinker Comparisons: Wet vs. Dry
  F. MacGregor Miller, Construction Technology Laboratories, Inc., Laura Powers, Wiss, Janney, Elstner Associates, Inc., Jolanta Zdunowska, Lafarge Polska, Kujawy Cement Plant, and Jerzy Zemajtis, Construction Technology Laboratories, Inc.
  • In 1996, the Kujawy plant in Poland was operating three wet process kilns at 1200 tpd. Recently, these kilns have been replaced by a single dry process kiln. When taking into consideration this modernisation and the subsequent potential changes in clinker microstructure, it was decided to carry out investigations to monitor the clinker produced. The quality of the clinker made in the wet process kilns was high, and it was hoped that by employing the dry process, the standard would be maintained.
    Thorough investigation proved that the clinker produced using the more efficient dry process has a comparable, if not higher, overall quality compared to the wet process clinker. Changing from wet to dry results in changeable raw material processing and fluctuations in the temperature profile in the kiln. Neither of these factors appears to impact negatively on the quality of the product.
• Tracing the Benefits
  Mark W. Dirken, PANalytical, and E. van der Broeck, ENCI Maastricht, The Netherlands.
  • The Dutch company ENCI investigated X-ray fluorescence (XRF) for trace element analysis. XRF spectroscopy is already widely used in cement plants for process and quality control, but has tended not to be used for trace element analysis because of the very low detection limits required. It is known to cope well with large samples and is easily automated.
    Results from XRF analysis were compared with those obtained using inductively coupled plasma emission spectroscopy (ICP) in external certified laboratories. The reproducibility of XRF was also assessed. A number of materials were investigated; the results for limestone and animal meal are also discussed. Pro-trace calibration for trace element analysis had been set and was used for all measurements. The Pro-Trace calibration comprises a combination of software algorithms and a suite of set up samples, designed to get precise net intensities. This resolves the problem of finding proper reference materials for the wide range of materials tested.
• Manufacturing Solutions for Concrete Performance
  Linda Hills, Senior Scientist, and Fulvio Tang, Principal Scientist, Construction Technology Laboratories, Inc., USA.
• In this paper, Construction Technology Laboratories, Inc., describe examples of cements with various sulfate properties, including their reactions during early hydration and their resulting paste properties. They outline methods to characterise cement paste behaviour and identify sulfate requirements, and suggest manufacturing solutions to optimise sulfate.
• Taking Control
  Ludger Diekmann, Polysius AG, Germany.
• The Tong Yang Cement Corp. is one of Korea’s longest established and most prolific cement producers. In 2002, Polysius AG, Germany, was contracted to replace the existing control system with the POLCID® NT process control system, which is based on standard PC technology.
  This type of system offers a number of advantages both in terms of flexibility, allowing it to be operated and monitored across a widespread area by a large number of personnel, and benefits of software, based on Rockwell Automation software and enhanced by Polysius to meet industry requirements. Polysius created a software tool that automatically converted the old system to be compatible with the new one. This eliminated the occurrence of programming errors.
  The changeover period took place over three phases and 15 days were available for changing over the kiln line to the new control system.
  Quick changeover to the new control system within one maintenance stoppage period, and continued application of standard technologies has ensured efficient operation of the plant.
• HOTDISC Installation
  Asgeir Kvitvik, Project Manager, Norcem AS, Kjøpsvik, Norway.
• The Norwegian company Norcem A/S Kjøpsvik, part of the HeidelbergCement Group, installed the first HOTDISC reactor for waste fuels burning in 2002. The work consisted of five phases. The first involved the delivery of all materials by F.L.Smidth. The first kiln stop occurred in the second phase. The riser duct to the calciner was modified with new expansions, and preparations for assembly of the HOTDISC were carried out. Phase 3 involved the assembly of the HOTDISC. The next phase saw the connection of the HOTDISC, inlet sluice and material pipes. The final phase consisted of the commissioning of the system. The reactor burns waste materials such as tyre pieces and cut wood chips. Good operational results have been achieved. Further tests are being carried out to increase the variety of fuels used.
• Burning Rubber
  Robert Stöppel, BEUMER Maschinenfabrik GmbH & Co. KG, Germany.
• Throughout the world used tyres accumulate in immense quantities and result in long term dumping sites that will never rot away. For the purpose of environmental protection it is therefore only sensible to look for ecological, as well as economical, methods of recycling this valuable raw material.
  Advanced concepts from BEUMER enable a flexible use of used tyres and other alternative fuels. These systems have proven their suitability for practical application in numerous operating installations.
• Waste Materials as Fuel
  S.K. Maheshwari, Senior Executive President and Chief Manufacturing Officer, Grasim Industries Ltd, India.
• In India, as fuel demands continue to rise, pressure is exerted on the limited resources of conventional fuels. Based on current estimates, the limited, non-renewable, conventional fuels will only last for the next 70 years. In order to counteract this problem, Grasim Industries Ltd has initiated an ongoing program to burn a wide range of waste fuels at its plants across the country.
  Petcoke was initially employed as an alternative, although this presented supply and cost constraints. After having witnessed the success of alternative fuels in the West, municipal, industrial and agricultural wastes were tested with positive results in India. A complete system has been installed by the company for unloading, feeding and burning solid wastes in the precalciner at its Grasim South cement plant in Tamilnadu.
• Made to Measure
  Karsten Brink Floor, FLSmidth Airloq, Denmark.
• FLSmidth Airloq, Denmark, has undertaken investigations into the importance of reliable gas analysis. Connected to this is the development of the company’s KilnLoq probe, which can be operated as easily as an air cannon or shock blaster. This piece of equipment was designed to be simple, strong and reliable. The process of gas analysis that results from using the probe has a high run-factor of more than 95% and consistent data is provided. Additional advantages are emission reduction and better clinker quality.
• Flue Gas Emissions Monitoring
  Stuart Harris and Ian Watson, Land Instruments International, UK
• Flue gas monitoring is an integral process control technique in the dry process of cement manufacture, and fast response CO monitoring is considered to be the most effective manner with which to prevent combustion that could otherwise result in a mill being destroyed. Methods of protecting ESPs against ignition are also discussed, as are the advantages of using a portable flue gas analysis system to measure combustible products present in the flue gases. The need to closely monitor dust emission levels in order to adhere to legislation plays a major role in flue gas emissions monitoring.
  The varying processes of monitoring pollutant emissions are all strictly governed by the need to comply with environmental legislation and be accepted by those working in the industry. This results in equipment manufacturers offering competitive prices that benefit plant operators.
• Friction Drives
  Kurt A. Geiger, Brian P. Keffe, and Gary R. Kotz, F.L.Smidth Inc, USA.
• The rotary kiln is perhaps the single most critical piece of equipment in a cement plant. The self-aligning kiln roller support has been introduced as an innovative drive technology for modern two-support kilns. Such kilns are statically determinant and it is possible to drive the kiln’s rotation through its supporting rollers by means of this special design. The article examines the benefits of the friction drive, such as the elimination of the traditional ring gear and pinion, by which the new drive system is free from the traditional problems of alignment, wobble and lubrication of the kiln girth gear.
• Use of secondary materials at Rohrdorf
  Heinrich Rodlmayr, Rohrdorf Cement, Germany.
• The Rohrdorf plant is situated in Southern Bavaria, Germany. The company has a definite policy with regard to sustained development and the associated ecological and economical benefits of employing secondary materials and secondary fuels.
  The quality of the produced cement, however, remains of paramount importance. One example of a secondary material employed is used foundry sand, which increases the silicate modulus in the clinker.
  Investigations have proven that it is possible to add this substance unground (in accordance with regulations) to the hot meal via the meal duct at the lowest cyclone stage. In addition, special lime is added to the used foundry sand to ensure equilibrium between the SiO2 and CaO necessary when producing clinker. Paper waste is also used, as are shredded used tyres and plastic based waste materials.
  After careful monitoring of the processes involved, the use of secondary materials has brought significant benefits to the plant.
• Alfranjet®: Five Years On
  Carlos Domínguez Merino, Jesús Gómez-Millán Roselló, Ignacio Movilla Heredia, and José Miguel Gandullo, Refractarios Alfran, Spain.
• At the end of 1997, the Spanish company Refractarios Alfran introduced the Alfranjet® system for the high velocity application of heat resistant concrete with low to very low cement contents. The first system installations were in cement plants in the Iberian Peninsula in 1999. Since then there have been over 25 installations.
  The system is particularly effective in the heat exchanger and the inlet arch.
  There are two main advantages relating to the system concerning the time of installation and environmental impact. The average time for projection through to completion is 1.3 days, where work is conducted in one shift. The installation of the heat resistant covering does not involve contaminants and no dust is generated.
• Better Grinding at Jaypee Bela Cement
  A.K. Dembla, Humboldt Wedag India, V.K. Jain, Arvind Nema, Jaypee Bela Cement, India, and S. Strasser, KHD Humboldt Wedag AG, Germany.
• Jaypee Associates Ltd (JAL), owner of the Jaypee Bela cement plant at Jaypee Puram, India, contracted Humboldt Wedag India (HWI) and KHD Humboldt Wedag (KHD), Germany, to upgrade the grinding capacity of cement mill 1 in 2002.
  The aims were to increase capacity from 150 tph to 250 tph with a Blaine fineness of 3000 cm3/g; reduce specific power consumption by up to 12%; and maximise use of flyash to produce blended cements.
  The existing ball mill was to remain in use alongside a new grinding circuit, consisting of a roller press, V-Separator and SKS-Separator from KHD. All equipment was supplied on a turnkey basis by HUI and the company delivered complete items during the period March – June 2003. Commissioning took place in January 2004 and the new system was connected to the existing ball mill circuit within 15 days.
• Dynamic Classifiers
  Blaz Jurko and Chris Oesch, Loesche America Inc., USA.
• Dynamic classifiers provide improved performances in pulverising applications. After much research, Loesche America has concluded that the benefits of dynamic classifiers far outweigh their static counterparts. The company has seen particular success with the LSKS high efficiency dynamic classifier, which has an increased production rate as a result of reduced internal circulation, resulting in less over-grinding. Dynamic classifiers can be easily fitted to existing mills.
• Afs for Double Shaft Lime Kilns
  E.D. Cristea, T. Christiansen, and O. Collarini, Cimprogetti S.p.A., Italy.
• Cimprogetti S.p.A., Italy, has examined the use of alternative fuels for double shaft regenerative TWIN-D® lime kilns. Various factors were taken into consideration, including the cost of exploitation, fuel availability, finished product quality requirements and the environmental impact.
  Two case studies are presented here. The first concerns a 200 tpd Twin Shaft Regenerative kiln fired with pulverised anthracite installed at the Puklina plant in Bulgaria. The second focuses on a 260 tpd TWIN-D® NS 55 kiln at the Karabuk plant in Turkey fired by coke oven gas.
  In both cases, the two substances proved their worth as alternative fuels when used with these types of kiln. The quality of quicklime produced was consistent and in accordance with the client specification.
• Biomass Lime Kiln
  Jimmy Chan, CAO Industries Sdn. Bhd., Malaysia.
• The CAO Group is a major lime supplier in Malaysia, and as such they were in a prime position to pioneer a new engineering technique. This involved operating modern vertical lime kilns with waste biomass as fuel.
  In 2002, CAO entered into a partnership with the Italian company, Italiana Forni to develop a 100 tpd vertical lime kiln based on locally available waste biomass materials. This kiln went onstream in July 2003. The project was a success with an average burn rate of 97% over the first 10 months of operation using waste sawdust. Residual CO2 in the quicklime is less than 2%. Production costs are also lower than the cost of using fuel oil or gas.
  A second 100 tpd biomass lime kiln was ordered by the company and commissioning was recently completed.

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