Lively discussions between manufacturer and users
Four years after Loesche GmbH’s anniversary symposium marking 100 years of the company’s existence in Düsseldorf, Germany, the mill manufacturer organized a follow-up event, which was held from September 9 to 10, 2010. Some two hundred customers and associates attended the interesting, varied and extremely well-balanced series of presentations at Düsseldorf’s Hotel Intercontinental.
In his opening speech, Dr.
Thomas Loesche (Fig. 1) drew attention, in particular, to his company’s major investments in its technology center in Neuss, the overriding priority now being that of cutting energy and water consumption by careful selection of grinding parameters. Loesche is still a specialist for grinding plants with high throughputs. In addition to large mills, however, more and more small and even mobile grinding plants are being inquired. Loesche as an innovative company accepts this challenge and is developing new concepts for these applications as well.
The two-day lecture program began with Dr. Joachim Harder‘s paper entitled “Current situation and outlook of the mineral resources industries”. In it, he made clear that despite the global crisis the developing countries were manifesting positive rates of growth. China is now the driving force in mining, consuming more than 50 % of global metallurgical coal and iron production. Environmental aspects are also set to play an ever more significant role in technological development. The quality of basic mineral resources will inevitably decline.
In his address on “Hydration of cement and the microstructure of concrete”, Prof. Dr.-Ing. habil. Jochen Stark examined, in particular, the interaction between the formation of cement phases in the nanometer range and the resultant microscopic properties of the cement and concrete products. The Finger-Institute in Weimar purchased during 2009 a new, high-resolution Nova NanoSEM scanning electron microscope. This instrument permits investigation of hydration processes at normal pressure and without steam scouring. This has made it possible for the first time to depict, without artifacts, the real structures of CSH phases.
Continuing Prof. Stark‘s topic, Prof. Dr.-Ing. Horst-Michael Ludwig (Fig. 2), of the Bauhaus University of Weimar, then focused, in a presentation with the title “Production and properties of sustainable efficient cements and binders”, on the latest research results in the field of reduction of CO2 in the production of cement. A shift from purely Portland cements in favour of Portland composite cements is even now apparent. Ludwig warned, however, that the availability of composite materials is itself subject to certain limits. For this reason new alternative binders are coming to the fore around the globe, both in cement production and in materials research. Ludwig examined three potential routes for enhancement of the initial strengths of composite cements, a criterion of manifold importance for the processing and use of these materials, such as the use of organic or inorganic additives, the use of nucleating agents and the exploitation of tribochemical effects during grinding.
In addition to the search for supplementary cementitious materials (SCMs), research in this field is now also devoting great attention to finding new hydraulically active substances, a goal, to which Ludwig also envisaged a number of different routes:
– Geopolymers (alkali-activated metakaolin, slag or ash, OPC 0 %)
– Supersulfated cements (slag, anhydrite, OPC < 5 %)
– Calcium sulfoaluminate (-ferrite) belite cement
– MgO-based binder systems (TecEco, Imperial College)
– CSH-binders based on autoclave and activating grinding technology
– Organic adhesives for aggregates (BASF)
– C-fix (Shell technology)
Dipl.–Ing. Andreas Schaab, of HOCHTIEF Consult Materials, illustrated in his lecture entitled “The new Gotthard base tunnel – concrete for the world’s longest tunnel” the forces exerted by a mountainous rock mass on fixing and support elements during tunneling, and the resultant special demands made on the concrete roof and its anchoring.
In his paper on “Loesche mills for cement and additive grinding”, Dr. Daniel Strohmeyer, Sales Department Loesche GmbH, concentrated intensively on the use of these mills in cement production, illustrating the various operations in which Loesche mills can be employed (Fig. 3). As he stated, of particular interest to users is the analysis of clinker grindability as a function of mineral composition and clinker structure. Strohmeyer’s paper was based, not least of all, on his own experience in the installation of 210 Loesche mills for cement production around the world, of which some 140 are currently operational.
“Vicat’s experience with Loesche VRM” was the title of a paper presented by Dominique Renié, Technical Director at
Vicat (Fig. 4), who cited a series of mill projects completed with Loesche in order to outline both problems which had occurred, their solutions, and other technical improvements. So-called “fine tuning” of mill parameters had, for instance, made it possible to cut energy consumption, while design modifications reduced grinding roller attrition. Renié concluded by emphasizing that Loesche had at all times assisted Vicat with the extensive adjustments performed, deploying commissioning engineers to the sites for this purpose, this support having ultimately permitted significant savings in energy costs.
The following paper transported the audience to AfriSam’s Roodepoort plant in South Africa. Gavin Venter (Fig. 5), of AfriSam Process Optimisation, described his experience during the project award and commissioning phases for a new vertical mill for grinding of cement with a high specific surface area. Loesche obtained the contract, against stiff competition from a number of other bidders, with its short delivery times, lower energy consumption and longer guarantee periods. Another major factor, among many in Loesche’s favour, was the concept of implementing the project via their subsidiary in South Africa. A series of adjustments were necessary after installation and initial trials of the mill; the water-spray system, the angle of inclination of the grinding rollers, and the air supply system were modified. The new installation nonetheless achieved the desired success, with the attainment of the agreed targets, a major advantage also being the mill‘s easy operability.
Prior to the afternoon session, focusing on mill technology, there followed a further user report on a mill modernization project at Saint Pierre la Cour. Wolfgang Stoiber (Fig. 6), Divisional Senior Expert in Grinding at Lafarge, described the installation of a Loesche LM 46.2+2C for grinding of cement, the essential targets being energy-savings and expansion of capacity. The following systems were optimized at commissioning of the mill: water injection, dam-ring adjustment, material feed and mill ventilation.
Michael Keyssner, Director Research & Development Loesche GmbH (Fig. 7), spoke on the “Latest developments in Loesche mills for reduction of energy consumption and CO2”, examining in his presentation a series of research projects, including the development of a vortex rectifier for reduction of the pressure drop in the mill and classifier. The optimization was carried out with CFD simulations, and can achieve energy-savings of 4 to 8 % for the mill blower. New S-roller geometry and positioning permits improved preparation and venting of the grinding bed.
The paper presented by Michael Buchanenko, Project engineer Loesche GmbH, took as its subject “Energy savings in clinker/slag grinding installations via utilization of waste heat” (Fig. 8). Annual energy-savings can amount to as much as 13 %, but need to be balanced against investment costs of around 500,000 €. The installation of a heat-recovery system also offers additional benefits:
– Use of the condensed water as mill-injection water
– Reduction of false air entering the system without control, replacement with preheated ambient air
– Preheating of fresh air for center air flaps
– Partial replacement of recirculating air with preheated fresh air => lowering of dew point => potential for lowering the mill outlet temperature (if not restricted by other factors). Replacement of moist recirculating gas with preheated fresh air is expected to have beneficial effects on mill operating behaviour and product quality.
Finally, Tony Hadley (Fig. 9), of Baobab Advisory SARL, presented “The cement value chain: A non-technical view of process optimization”, calling on suppliers to devote more attention to global industrial trends and tailor their ranges more closely to the needs of decision-makers at marketing level.
The second day of the symposium commenced with a paper entitled “Achieving emission compliance in a cost-effective and innovative manner” by Ed Jamieson, Group Head Emissions Control, RWE npower, who directed particular attention to adherence to NOx and SOx limits.
In his presentation entitled “The Loesche Coal Enhancement Process (CEP)” (Fig. 10), Gerhard Salewski, Corporate Manager Sales & Marketing Loesche GmbH, examined the topic of coal grinding, focusing in particular on the preparation of lignites and sub-bituminous coals for a range of applications. The concept behind this process is aimed at producing higher-quality fuels from lower-cost grades of coal with longer foreseeable availabilities.
Dr. Christian Barczus, Hot Gas Generators Loesche GmbH, and André Bätz, Test Center Loesche GmbH, examined the subject of “Coal-fired HGGs, applications and studies for the mineral resources industries” (Fig. 11) in greater detail. They outlined the following aspects:
– Actual research results from a pilot plant of a coal fired non refractory lined LOMA-HGG
– The conversion to industrial scale
– The replacement of oil- or gas-fired HGGs by coal-fired HGGs
– The replacement of refractory-lined systems with LOMA- HGGs for faster temperature control of drying and dry-grinding processes
– The use in coal enhancement systems and replacement for syngas-fired HGGs in coal gasification plants (IGCC-plants)
– Construction of a LOMA test facility with 1 MW thermal in the Loesche test center
In a concise but nonetheless extremely illustrative overview, Oleg Matyushenko, of Mechel Holding, outlined the special requirements made on the transportation, storage and processing of coal in Russia, examining in particular the possibilities for the use of vertical roller mills and the great potentials in the field of plant modernization.
Although increasingly large mills had been favoured at the previous Loesche symposium, the trend now is also towards smaller, mobile and compact grinding plants (Fig. 12). Matthias Authenrieth, MD of Loesche Automation GmbH, presented to the audience the grinding plant CGP mobile which is housed in a container. In a second part of his lecture, Authenrieth highlighted the Industrial Automation Department. He also presented a whole series of new products for the control and automation field, such as LM control®; LM expert®; LM sim® and LM remote®.
Andre Bubholz, from Siemens Flender AG, showcased the new Flender EMPP gearbox for vertical roller mills. The EMPP gearing system offers a number of advantages, such as the prevention of load surges, with rapid restoration of the power-supply line, an optimized power transmission between the drive and the mill, a reduced number of trouble-vulnerable components at am extended power range up to 15 MW without additional cooling.
“Increase availability, enhance reliability, reduce costs” was the motto selected by Ralph Viebrock, Customer Service Loesche GmbH. Viebrock reviewed the individual training (internal and external), service contracts, audits, support, upgrades and retrofits/technical developments, tailored services and spare parts service ranges in more detail for the audience.
Bob McQuiston, of Lehigh Cement, Union Bridge, passed on to the audience his experience with Loesche after-sales service, the company having established a four-stage internal initiative for the improvement of individual processes and procedures, and thus customer satisfaction. Lehigh and Loesche, with support from MSR Consulting, jointly organized a one-day workshop. Not only Loesche benefited from this workshop: subsequently, Lehigh employees also had a better understanding of the processes and procedures involved, and had established closer contacts with the mill-maker’s service engineers. McQuiston closed his address with the words: “I encourage every one of you to participate in this excellent initiative!”
Dr. Robert Salter, of Mineral Solutions, provided an overview of non-ferrous metals operations in Canada and the United States, with particular attention devoted to a comparison of the technologies used in the refinement of nickel ores.
Comminution of ores in Loesche mills: “Technology for the future” was the concept postulated by Carsten Gerold, Research & Development Loesche GmbH. Compared with the cement industry, different demands are made on grinding during ore dressing going beyond pure comminution. It has been underlined that the Loesche grinding technology meets the globally changing requirment of the mineral industry, i.e. more energy-saving and more efficient comminution technologies with simultaneously simplified process control.
At the end of these two extremely interesting and instructive days, which were notable for an intensive interchange of experience and opinions, Dr. Thomas Loesche formally closed the program of papers. The Loesche symposium continued, however, the participants having the opportunity of further intensifying their contacts at a gala dinner held at the Zollverein Colliery heritage site in Essen.
