CEE Oct-Dec 2002

that the /\l ite content is boosted by this solid solution at the expense of interst ttJal materi al. as the A l,O . - ' and Fe ,O co nt ained i n so li d - ' solution increases the proporti on or the total present as A lite, and leaves less A l 2 0 _, and Fe 2 0 1 availabl e for formati on or the C 4 AF and . C 1 A w h ic h mak e up the inters ti tial material. Further deviations form Bogue C,S conknt arise because of non– equili brium cooling in an industri al cement kiln. the solid solution of trace oxides not considered in the !3ogue cquation. and fundamental alterati on of the Ca0-Si0 2 -/\ lp ; phase diagram by some spec ies. most notably CaF~. "Wiwt is not measured, cannot be contro ll ed". !\ long with Dr.Chromy. A lfredo Santos-An.:eo and Conrado Gaytan of Cemex arc strong advocates or employing cli nker microscopy to measure and contro l th e rea l mineral ogy or clinke r. There arc also a growing number of papers on the possibi li ties of X RD and dynamic Reitve ld /\nalysis to achi eve the same goa l o f meas ur in g and cont rolling real cli nker mineralogy. D r . C hrom y ad voca te s th e followi ng steps to rea l ise a true c li nker-mineralogy quality control system. • continuously measure cl inker ox itle composit ion and tru e mineral composition ( by mi c r oscopy of X RD and· dynamic Reitveld Analysis) • calculate devi at ion !'rom target cli nker mineral composition translate thi s into a deviation !'rom cIinker chemistry targets (L F. SM . etc) • • • adju st kil n feed chemi st ry targets to correct deviations or clinker mi neralogy from target control kil n feed chemistry to these modified targets. Adoption o f this true clinker– mineralogy quality con trol regime leads to further cross– checks and ca libration poss ibil ities to enhance the quality control • as the cli nke r ox ide composition and true mineral composition are known. the relationship between the t\\O can be determined by multiple regression techniques • the coefficients represent ing thi s relationsh i p can be conti nuous l y kept tn calibration as new measurement s become available • w hen true m ine ral ogy measurement is not avai Iable. due to equipment maintenance or failure, the true mineralogy can be estimated using the ca li brated multiple relati onship w i t h oxide composition. These Colombian conversions avo i d th e use o f !3 u lgar ian constants to convert from oxides to clinker mi neral composition. Expert systems giv i ng good agreement with true m inera logy have now been developed. These allow tr ue mineral ogy to be pred icted from the full ana lysis of the c lin ker inc l ud ing all minor com'ponents. Courte.\)' : fnlemallonol Ce111ent Reriew. SefJ. 2001. Pp65-66, E-11wil: il!(o(aiCem Neu.:o. 11k Web: CemNet. co. uk OPTIMUM MIXTURES Dr. Armin Gre11ne. J-/A ZEilf.·lG & EPR Cimhl I. Thi s year, when the Unye C imcnto pl an t in Turkey w as upgraded to increase its capacity. a new primary crushing plant was suppl ied by 11 /\ZEMAG & EPR GmbH and put into operat ion to process limestone and clay. The two materials are stored in separate hoppers. fr om the re th ey ar c 36 extracted simu ltaneously by apron conveyor and Fed into the A P-PM 202~ IIAZCMAG prima r y impactor for processing. In order to guarant ee a consis tently hi gh qualit y and opt imum mi x of' the c ru shed raw ma ter ial pri or to stockpiling on the mi x ing bed. the conveyor belt downstream or the impactor is litted w ith a cross-bel t ana lyse r. whi ch continuo usl y analyses the compositi on o r the crushed materia I. The resu lts arc evaluated and used to control the speed or the teed-material apron conveyo rs. and thus optimi se the mixture. The overall capacity ofthe plant is I I 00 tph. Limestone. the main component w ith a f'eed size ol'up to 1.2m edge length, is processed at a rate ol' 800 tph. It is extracted from a I 00-m 1 capacity storage hopper by a 2.25 m w i de x I 1.6 m l ong apron conveyor and fed directl y into the impactor. The clay. wh ich has a ma:"-.imum feed size of 500 mm, is extracted at a rate of 300 tph from a 30-m ' capa c ity hopper by an apron conveyor installed at right angles to the limestone apr on conveyor. SincL: the clay has an H ~O content of up to 23%. the hopper has been specially des igned to ensure the trouble-free hand ling of th is sticky material. An apron conveyor 1.-1 m wide x 13.3 m long extracts the clay from the hopper. discharges it on to the limestone conveyor. whi ch is al ready covered w ith a laye r or limestone. thus preventing the clay from adhering to the main apron conveyor. T he material mi x is then fed directly into the impactor. The rugged impactor is litted wi th aheavy-duty. welded cast steel rotor type GSK 2022 , which is 2.0 111 in dia x 2.2 m w ide and dri ven by a 17.50 k.W mo to r . The limestone/clay mixture is crushed in a si ngle pass to generate the fo ll owing product granulometry: