Cement, Energy and Environment July-Sep 2002

' r In 1995 the plant was taken over by Zuari Agro Group. It was rechristened as Zuari Cement. Efforts towards saving energies and reduction m pollution level continued. In 1997 the pl ant capacity of I,850 tpd was achieved. Heat consumptio n and power consumption reached the level of 850 kCal/kg clinker and 121·kWh/ T respectively. In the same year a major decision was taken to go for upgradation , unbelievably, from I,850 tpd to 5,200 tpd using the existing kiln tube. The whole idea of upgradation is basically conceptualized from the maximum potential avai lab le with kiln. The ki ln (size: 4.55m diameter x 68m long), has got an effective vol ume of9 19.8m 3 , with 200mm refractory lining thi ckness. Especial ly with Ind ian raw materials it is now well established that specific volumetric loading (tpd/m 3 ) fo r kil n with precalciner system, can to up to a maximum 6. Ta rgeted heat consumption, power consumption and emission level were 720 kCal/ kg clinker, -- 105 kWh/T OPC and 50 mG / Nm 3 res pective ly. The challenge was taken up by a technical team from Zuari Cement, F.L. Smidth and Larsen & Toubro Lim ited. The upgradation plan to such a large extent was first of its kind in cement industry worldwide. The existing plant was augmented with addi tional Atox mills fo r raw ma terial and coal gri ndi ng. A separate line calciner (SLC) string was added in pyro sect ion. Conventional grate cooler was replaced by modern controlled flow grate (CFG) cooler. Cement gri ndi ng capacity was enhanced by additional two close circuit Unidan mill systems. 1\ fter initial teething trouble the pl ant was successfull y commi ss ioned in March 1999 . Averagc producti on now ach ieved is 5,500 tpd (at peak production of 5,750 tpd) with heat consumption of 95 kWh/T OPC. Emission level has been improved to ~ 50 mg!Nm 3 • Conrte:,y: 7'" NCB International Seminar on Cement & Building Materials, Vol. 2 Pp. IV56-65. Email: nccbm@gias.d /01.vsnl.net.in Web: lVlVw. cementresearch.com 'WHAT IS NOT MEASURED, CANNOT BE CONTROLLED' A lfredo Santos-Arceo and Conardo Gaytan Materials and Processes Department. Cemex Technology Division, Mexico. The pri nciple, 'what is not measured, cannot be controlled ', is the main reason for implementing control and measuring too ls in the cement making process. The four main fields where microscopy is app lied in Cemex plants are as foll ows: • Raw materials: to determine if th ese material s have a low degree of calcination or the cli nker is poor in quality, due to large quartz crystals. • Raw meal: to identify whether the raw mea l chemistty needs to be changed or not, or if the grinding or homogeni sation systems have to be improved. • Process: to correlate some of the c linker's mineralogical cha racte ri sti cs with some process parameters such as heating speed, 1i1ax i1!1 Um ki ln temperature, sintering time, primary and secondary cooling speeds, according to ONO's concepts. • Operati on: to defi ne and set operational parameters, such as primary air pressure, fu.el oil temperature, air tlow in cooler fans, speci tic material charge (ton/revolut ions) . With in thi s large and amb iti ous effort, is the idea of introduci ng a dig ita l image proce ss ing (D IP) system that provides a standard, easy and fast way to implement the microscopy evaluations. From this, MicroDIP was born, to standa rdise and speed up microscopy analysis for process and quality control. MicroDl P automa ticall y provides: • Phase analysis and percentage determination. • Crystal characterisation (area, perimeter and axes). • Crystal quantification (count and histogram). • Graphics display. • Analysis statistics. • Store of information. • Software evaluation. The study results revealed that the di g ifal image process ing techniqu e provides re liab le and repet iti ve measurements, whi ch always produce samples with a good colour defi nition for clinker phases. The system analyses crystals of all sizes produces a more rel iable results. This technique has shown the foll owing benefits during its use: • Faster, accurate and reliable results, 1n operation and statistically. • • • • • Less interpretation time and analysis, depend ing on the user's skiII. Error reduction in analysis Criteria standardisation. Cost reducrion of the analysis. Even those who are not special ists can carry out the analysis. Most plants still use the free Iime parameter to control clinker quality. However, the object ive of Cemex is to provide an integral control of the quality of the clinker us ing microscopy as a process control tool. So fa r, Cemex has discovered very surprising benefits from usi ng