Although South America accounts for only. VRMs in South

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Myron Hutchinson
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VRMs in South America Although South America accounts for only approximately 4.

In 2010, cement demand reached a magnitude of 3300 million t. This is an increase of 7.2% compared to 2009. 1 South America s share reached approximately 150 million tpa.

While the forecast for the years up to 2015 predicts stagnation or even a decline in cement demand for some of the world s regions, the expectations for South America are more positive.

1 VRMs in South America Although South America accounts for only approximately 4.5% of the worldwide cement market, the growth in this region and the positive outlook for the cement industry has increased significantly in recent years. In 2010, cement demand reached a magnitude of 3300 million t. This is an increase of 7.2% compared to South America s share reached approximately 150 million tpa. Brazil s share of 50% represents the largest market, followed by countries like Colombia and Argentina. While the forecast for the years up to 2015 predicts stagnation or even a decline in cement demand for some of the world s regions, the expectations for South America are more positive. The growth rate is anticipated to climb to 5%, while for Brazil that figure will be more like 8%. 2 Reasons for this M. Keyssner and B. Schroeder, Loesche GmbH, Germany, look at the success of the VRM in the South American market. might be improved conditions in the residential construction industry and reform of infrastructure in countries such as Colombia and Brazil. A strong domestic economy and the positive effects of upcoming mega events such as the World Cup 2014 and the Olympic Games in 2016 have played their part in this growth. The production capacity in Brazil is expected to increase by 30 million tpa by This will raise the annual production of this country to more than 100 million tpa. [Sep 12] Reprinted from World Cement

Figure 1. LM 63.4 at the Lamali plant. Figure 2. Section of Loesche mill. Figure 3. Different speeds between grinding roller and grinding track. Figure 4. Loesche roller module.

The rest are installed in plants with kiln lines. The first Loesche Mill for grinding cement clinker was delivered to Brazil in 1935.

In those days, the mill was equipped with steel springs in order to achieve the necessary grinding forces underneath the two grinding rollers.

2 Figure 1. LM 63.4 at the Lamali plant. Figure 2. Section of Loesche mill. Figure 3. Different speeds between grinding roller and grinding track. Figure 4. Loesche roller module. Cement plants In 2010, approximately 160 cement production plants were operating in South America. 1 About one quarter of these plants are stand-alone grinding units. The rest are installed in plants with kiln lines. The first Loesche Mill for grinding cement clinker was delivered to Brazil in This vertical roller mill, type LM 11, had a grinding track diameter of 1.1 m and drive capacity of ~60 kw. In those days, the mill was equipped with steel springs in order to achieve the necessary grinding forces underneath the two grinding rollers. Today, more than 85 Loesche VRMs can be found in many production facilities in South and Central America, either in operation or in the process of being installed. 3 They are used for grinding raw material, coal and various types of cement (Table 1). The largest Loesche mill in South America is at the Lamali plant operated by the cement manufacturer Loma Negra in Argentina (Figure 1). This mill is used for grinding raw material for cement and has been operating successfully since the year This mill, type LM 63.4, uses four grinding rollers, each with a mean diameter of 2.8 m. The diameter of the grinding track is 6.3 m and the rated power is 5400 kw. Based on decades of experience, the conical design of the grinding rollers incorporates roller shafts with a 15 incline. They roll along the flat, horizontal grinding track with the highest degree of efficiency during the grinding process, as has become the standard for all Loesche mills (Figure 2). The combination of inclined roller shafts and a flat grinding track results in an optimum pressure/shear forces ratio in the grinding bed. On the one hand, the magnitude of the shear forces is limited to a minimum by selecting the inclination angle of 15 in order to dissolve or prevent the agglomeration of ground particles. On the other hand, this is done to limit the increasing wear of the grinding components. This can be noticed especially on the areas of the contact surfaces between the grinding roller and grinding track at the inner and outer radius due to the relative speeds if the incline is less than 15 or is omitted altogether (Figure 3). The so-called Unification Concept was developed by Loesche about 10 years ago in order to allow the application of identical components for mills grinding either raw material or clinker. This concept was introduced in order to minimise or eliminate the potential risk during the development of new VRMs by using already tried and tested components, which primarily include dynamically loaded elements of the Loesche roller module (Figure 4). Depending on the required throughput rate or the material to be ground, it is possible to use 2, 3, 4 or 6 rollers of the same module with Loesche mills. The reason for this is the individual grinding rollers, guided by rocker arms without using any kind of support frame between the rollers inside the grinding chamber. Today, Loesche requires only five different roller module sizes to cover the entire capacity range from 50 to 1400 tph when related to average grindability and a raw material product fineness of 15% R0.09. According to Blaine, when grinding cements or granulated slag with Loesche mills, throughput rates of up to 450 tph at average cement clinker grindability and a product fineness of 3300 cm²/g, can be realised.

3 Table 1. South American orders dating back to 2006 Country LM type Qty Order year AR 35.3 D LOMA NEGRA C.I.A.S.A for InterCement BR C CSN Companhia BR 35.3 D CSN Companhia BR CSN Companhia Buyer Place Material Throughput (tph) Barker CL C Hormigones Transex Ltda. Puente Alto BR Votorantim Cimentos N/ NE S.A. BR Votorantim Cimentos Brasil S.A BR 20.2 D Hunter Consultoria for Holcim (Brasil) S.A. Ituacu Edealina Pedro Leopoldo BR Votorantim Cimentos Cuiaba CL C Lafarge Canada Inc. for Lafarge North America Ventanas EC C Holcim (Ecuador) S.A. Guayaquil MX 19.2 D SIME Engineering Sogamoso MX SIME Engineering Sogamoso BR C SOEICOM S.A. for Empresa de Cimentos Liz S.A. BR Votorantim Cimentos Brasil S.A. CL C INACESA Industria Nacional de Cemento S.A. PE C Cementos Norte Pacasmayo S.A. BR 26.3 D ThyssenKrupp CSA Companhia Siderurgica CL C INACESA Industria Nacional de Cemento S.A. Vespasiano Salto de Pirapora San Antonio Pacasmayo 2 Sepetiba Curico JM C Caribbean Cement Co. Ltd. Kingston MX C Cementos Mexicanos S.A. Tepeaca CS MX C Cemex Central S.A. de C.V. Yaqui (2CS) MX Cemex Central S.A. de C.V. Yaqui 2 RM MX Cemex Central S.A. de C.V. Merida VE C Cerro Azul Cement Consortium VE Cerro Azul Cement Consortium Maturin Maturin Mill motor (kw) Product fineness % R90 µm cm²/g % R63 µm % R90 µm cm 2 /g % R90 µm % R90 µm % R90 µm % R90 µm cm 2 /g cm 2 /g % R90 µm % R90 µm cm²/g % R90 µm cm 2 /g cm 2 /g % R90 µm cm 2 /g cm 2 /g cm²/g cm 2 /g % R90 µm % R90 µm cm 2 /g % R90 µm

Table 2. Performance data of reference cement mills Client Empresa de Cimentos LIZ Lafarge Cementos Bio Bio Plant Vespasiano Ventanas San Antonio Country Brazil Chile Chile Mill size LM 56.3+3 LM 46.

0% gypsum 6% gypsum 6% gypsum 34.0% GBFS 3% slag 30% pozzolana 6.0% limestone 21% pozzolana maximum 6% flyash Production rate 135 tph 107.

2 tph Production fineness 4875 cm²/g 4694 cm²/g 5000 cm²/g Spec. energy cons.* 39.2 kwh/t 32.8 kwh/t 28.

4 Table 2. Performance data of reference cement mills Client Empresa de Cimentos LIZ Lafarge Cementos Bio Bio Plant Vespasiano Ventanas San Antonio Country Brazil Chile Chile Mill size LM LM LM Installed power 5600 kw 3150 kw 1600 kw First operation Sept Feb June 2011 Guarantees Feed material 56.0% clinker 64.0% clinker 64% clinker 4.0% gypsum 6% gypsum 6% gypsum 34.0% GBFS 3% slag 30% pozzolana 6.0% limestone 21% pozzolana maximum 6% flyash Production rate 135 tph tph 45 tph Production fineness 4600 cm²/g 4650 cm²/g 5000 cm²/g Spec. energy cons.* 46.9 kwh/t 40.0 kwh/t 28.9 kwh/t Achieved Production rate tph tph 47.2 tph Production fineness 4875 cm²/g 4694 cm²/g 5000 cm²/g Spec. energy cons.* 39.2 kwh/t 32.8 kwh/t kwh/t *for mill, classifier, fan, auxiliaries PARTNER COUNTRY Indonesia Profit from one of the largest growth markets in the world! Based on this Unification Concept, the largest Loesche VRMs grinding cement clinker installed in South America (type: LM CS) use the same roller module as installed in the LM Table 1 provides an overview of Loesche vertical roller mills installed in South and Central America over the last few years. Mill design The essential requirements for the layout of the mill are the power necessary for the mill motor and the grindability of the material. The grindability will be determined through grinding tests at the Loesche Technical Centre if grinding material can be supplied in sufficient quantities. If such a specimen cannot be supplied, previous experience and standard values will be taken into consideration. Grinding tests take place at the Loesche Technical Centre using a VRM, type LM 3.6, with a grinding track diameter of 360 mm. The mill is equipped with two rollers and a dynamic classifier. The feed material is transported laterally onto the grinding table using a conveyor system (Figure 5). Here it is crushed by the rollers. The ground material is pneumatically transported through the grinding circuit to the classifier. Here the coarse material is separated from the fine. The air is drawn in from the surrounding area and heated by a hot-gas generator, providing the heat necessary to dry the grinding material. The grinding material that has not yet been crushed to the necessary product fineness drops from the classifier onto the grinding table below and is further crushed with incoming new material. The finished material leaves the mill and the classifier and the air flow transports it to the dedusting filter. For sampling purposes and in order to determine the product mass flow, the finished material falls through a rotary pipe distributor into a weighing container and is then fed to the product or disposal bunker. The clean gas downstream of the filter is drawn in by the mill s fan and escapes through the chimney, which allows a partial recirculation of the gas. Feel the pulse of the future now. bauma 2013 awaits you. Join us at this superlative trade fair with some: 500,000 visitors 3,300 exhibitors 570,000 m 2 of space Register online and save! Enjoy the benefits Go online and register directly:

Figure 5. Flow sheet Technical Centre grinding facility to the additional drying process. Dependent on the grinding roller size, the feed stock is precrushed to a feed size of less than 15 mm.

5 Figure 5. Flow sheet Technical Centre grinding facility to the additional drying process. Dependent on the grinding roller size, the feed stock is precrushed to a feed size of less than 15 mm. As the only variable parameter during the grinding test, the classifier speed is changed gradually in order to be able to pass through to the required range of product fineness. If the set classifier speed, the relevant process parameters and the desired product fineness are constant, then after sufficient steady-state time, representative product samples are taken and the product mass flow is measured by use of a weighing container. Likewise, the process parameters are measured and the specific energy requirement determined at the mill drive. The grinding components contain inserts that lose some of their physical mass during the course of the grinding test and thus provide an indication of the grinding stock s wear characteristic. The material-specific factors determined during the grinding test will flow into the respective design of the mill. Applications Loesche clinker and slag mills were introduced into the market almost 20 years ago. Table 2 lists some recent references in South America. Mills between 1600 kw and 5600 kw installed electrical power are already in operation (Figure 6). Figure 6. Loesche Mill Type LM CS, San Antonio, Chile. Grinding stock tests are carried out as standard, using constant grinding and classifier geometry and constant set points for the grinding pressure, grinding table speed, mill gas flow and temperature downstream of the mill. Here the feed moisture is chosen to be less than 6% in order to avoid a reduction effect on the throughput due Outlook Loesche has a significant presence in Central and South America. A high degree of availability, reliable operation, and the efficient use of energy are the hallmarks of Loesche mills. The mill flexibility provides the owner/ operator with the option to react quickly to future market changes and at the same time keep production cost to a minimum. The module system makes it possible to interchange grinding units for cement raw material and cement and keep the cost for replacement parts low. References 1. MADEIRA, R. South America Cement Market, A TEC GRECO Seminar, June 2011, Sao Paulo, Brazil; cementseminar2011-atecgreco.com/palestras/p_24.pdf 2. PAES, E. Opening Keynote Address, Latin America CemenTrade, October 2011, Rio de Janeiro, Brazil; cmtevents.com/aboutevent.aspx?ev=

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