Howard Klee, former director of the WBCSD’s Cement Sustainability Initiative (CSI), summarized the global cooperation between twenty-four member companies in the CSI. The global cement and concrete industry, confronted with a range of challenges, can be, as he noted, the key to sustainable economic development in rapidly expanding – and changing - societies. Thanks to the CSI, there is now a firm basis for fundamental collection of data and knowledge, their annual updating, for all discussions of the climate and of industrial emissions, energy and resources management, and for occupational health and safety. The CSI has been widely recognized as the leading interlocutor for governments and NGOs.
Substantial energy savings have been achieved in recent years, while product-related CO2 emissions and other parameters have been significantly improved. Cecilia Tam, of the International Energy Agency, illustrated the current retrograde trend on the global energy market. Oil and gas production are undergoing a renaissance, with dependence on imported oil is rising in many countries, while others are redoubling their efforts to improve energy-efficiency. She surmised that two-thirds of the economic potential for improvement of energy-efficiency up to 2035 remains untapped in the building, power generation, transport and general industry sectors, thus implying a key role in the transition to new energy structures.
Joe Harder, of OneStone Consulting, examined the pattern in the increase in cement kiln capacity, which has slowed in the last few years. Both technical and economic reasons speak in favor of maximizing clinker output, which recently peaked at around 13 000 t/d. The slower rate of growth in the economies of a range of regions has contributed to a trend toward grinding, however. The enormous challenges set by the need to cope with rising energy costs have also resulted in the replacement of existing grinding installations with new mills. Some two hundred mills are ordered each year – not counting China – equating to 45 to 50 million t of capacity in the 2010 to 2012 period. In most cases, however, replacement investment is accompanied by an increase in facility production rates or the installation of new capacity. Harder also focussed on the trend toward waste-heat-recovery (WHR), which is extremely common practice in China, where 739 units (95 % of global capacity) are operating as conventional steam-based systems for internal power generation.
Andreas Schaab, of Hochtief Construction AG, presented the viewpoint of a user – the construction industry. He spoke of the specifications and requirements which cement must meet on a highly competitive construction market, and cited an example to illustrate why cement for use in spraying (shotcreting) and in tunneling applications must satisfy extreme demands with effectively zero tolerance. Such shotcrete is chemically fine-tuned, and functions at its limits, having to be mixed, transported and pumped across long distances and then being required to harden at the point of impact and develop its strength at precisely the right moment. Therefore, it is immensely important to detect problems, and to discuss them openly, and to get a common comprehensive and effective quality management system covering the whole process chain.
Finally, Martin Schneider, CEO of the VDZ, emphasized just how such a quadrennial specialist congress showcases all the progress and advances achieved in a large range of fields. Driven by the need to reduce production costs and cope with unstable economical conditions, the cement industry and its equipment suppliers are constantly seeking individual solutions and approaches to improve the cement production process.
There are currently no groundbreaking innovations in the clinker-burning process, but unceasing process optimization continues. Modern clinker coolers with efficiencies of around 75 % are now available, as are burners designed specifically for high thermal substitution rates of adequately pretreated alternative fuels, while high-efficiency SNCR and SCR have proven their feasibility in field tests. Good cooperation with the vari-ous equipment suppliers has resulted in advances in the grinding of feed materials and cement, with parallel improvements in energy use and energy consumption.
Intensive research work is being devoted to CO2 capture and storage, but potentials are, at the least, extremely low. A case study concentrating mainly on the German cement industry discloses maximum potential savings of only 14 %, even if all kilns and cement plants are assumed to be constructed entirely on a “greenfield” basis. All these savings will, on the other hand, be balanced out by increasing extra equipment, for economic utilization of alternative fuels and feed materials, waste-gas cleaning, and the reduction of particulate matter and NOx emissions. Finer grinding of cement, and the increasing use of GGBFS, a cement ingredient more difficult to grind than clinker, will also increase power consumption.
Highly competent experts from the fields of plant engineering, equipment supply and operation provided an impressive overview during the following days of the congress. Starting with the visions of and the future challenges perceived by cement-process suppliers such as FLSmidth A/S, KHD Humboldt Wedag GmbH, Sinoma International Engineering Co. Ltd. and ThyssenKrupp Resource Technologies AG, the second half of the day focussed on a presentation of environmental technologies by Dyckerhoff AG, and an overview of the potentials and limitations of SNCR technology. Schwenk AG discussed its experience on projects orientated around high dust at Mergelstetten, while the Rohrdorf Group examined low dust at its Rohrdorf plant and Lafarge CTEC Vienna GmbH semi-dust at its Mannersdorf plant. Wopfinger Baustoffindustrie GmbH discussed the combination of NOx reduction with the need to solve odor problems from a regenerative thermal oxidizer (RTO) installation resulting from the use of biodegradable paper rejects.
Titan America allowed us a look behind the US program of mercury-reduction measures. Mercury emissions are addressed at global level by the United Nations Environmental Program (UNEP) in its world mercury assessment. Due to its high vapor pressure, mercury is extremely volatile, and is routinely found in natural telethermal deposits of coal and other minerals. Mercury abatement strategies are to be backed up by input controls for various alternative feed materials and fuels. The most effective provision, however, is dust bleeding to interrupt mercury cycles in the pyroprocess, combined with sophisticated temperature control. The EPA has recently begun to favor alloying in gold-containing filters, as a result of the fact that there is, as yet, no suitable abatement technology available to meet these stringent limits.
HeidelbergCement Group Brussels kicked off the parallel session on sustainability, and energy/resources utilization, ultimately guiding the audience to the quarry and modern experience in the protection of biodiversity. Holcim discussed its experience with WHR at its Untervaz plant, after which Prof. Werner, of the Technical University of Vienna, compared the energy balances of WHR and power generation for the cement-clinker process.
Gernot Kirchner (Lafarge Zement GmbH), chairman of an internal VDZ workgroup, examined the question of precisely how efficient cement-making has already become, dispelling false hopes of enormous potentials for future improvement. The session was rounded off by Stefan Schäfer, who spoke on VDZ support for enhanced cement industry training provisions. Ball mills, still a widely used technology, were the focus of the VDZ mill survey. Aiming at boosting understanding of the comminution process, this tool helps in increasing individual grinding efficiency, also a topic in subsequent sessions that afternoon.
FLSmidth A/S illustrated just how versatile an optimized grinder can be, while Gebr. Pfeiffer SE reported on its largest-ever multi-vertical roller mill, recently completed in India. The grinding of feed materials and cement remain the highest consumers of electrical energy, for which reason a great deal of rational effort is being devoted to the reduction of specific electricity consumption. Loesche GmbH demonstrated the importance not only of energy-efficiency, but also of good reliability and grinding process versatility. Vertical roller mills (VRM) are the most popular method for grinding of feed materials, whereas other mill types and combinations are used for finish grinding. ThyssenKrupp Resource Technologies AG showcased its Quadropol RD, the world’s first VRM to incorporate driven rollers.
HeidelbergCement examined the production of slag cement by means of separate grinding of OPC and slag, with downstream blending. The Hefei Cement Research Institute addressed the topic of grinding in an HFCG roller press, and the potential applications for this process.
The formal congress dinner in the evening featured the award of the Klaus-Dyckerhoff Prize to Duncan Herfort for his outstanding work in the field of cement hydration chemistry.
Alternative fuels are now replacing fossil fuels to a significant extent in many countries around the world. The cement industry has developed technologies and burning strategies to permit the use of even more heterogeneous waste materials than in the past few years. These methods are based on improved knowledge of waste management and preprocessing, improved input control and improved burner technology. Unsatisfactory and inadequate quality of preprocessed fuels from inexperienced suppliers can cause serious problems during co-processing, however. Buzzi Unicem presented a new solution, in order to demonstrate how the moisture content and biofraction of certain calorific fractions originating from solid municipal waste can be reduced. After bio-drying and near-infrared (NIR) removal of PVC, his chain mill comminutes the particles so efficiently that they can be optimally combusted in the sinter zone.
Another drying strategy is capable of significantly reducing moisture and improving combustion characteristics by using the available waste heat to operate a drum dryer. This technology was highlighted by Cemex Poland.
The Italcementi Group examined a tender for a modern 3000 t/d line incorporating innovative and sustainable production methods, while the VDZ and Jura-Cement-Fabriken AG examined low-temperature corrosion in general, and kiln-shell corrosion, in particular.
The parallel session was devoted in particular to the future of cement and to new performance requirements and characteristics. All current developments focus on the reduction of CO2 emissions during production. Calciumsulfoaluminate clinker, ternesite, high-belite Portland cement clinker and CELITEMENT form the basis for low-carbon cements which are expected to gain small portions of the overall market in the near future, depending on their performance and market acceptance, in particular.
There was no doubt that an exciting future awaits the technology of cement production. The challenges confronting the cement industry will nonetheless remain. These are, chiefly, the reduction of production and maintenance costs or improvement of quality and performance, and the sector’s interaction with both regional and global issues. These constitute the framework in which cement-making must demonstrate its social responsibility throughout the world.