Clinker burning time

Photograph 6-5 Amber belite crystals in 44- to 75-pm fraction of crushed clinker. Low maximum temperature, long burning time, slow heating rate, moderately slow to slow cooling. Coal-fired, wet-process kiln. (S A6620)... 

Spots in clinker Local increase of individual components of raw material low burning degree (temperature too low or burning time too short) low lime content (Gille and others, 1965)... 

Photograph 7-79 Free-lime nest colored by water etch in polished section. Chemical analysis gave clinker free-lime value of 2.69%. High maximum temperature, moderately long burning time, moderately slow heating rate, moderately slowly cooled, 31 MPa. Gas-fired, dry-process kiln, 3000 tons/day. (S A6697)... 

Raw Material Proportions. The three main considerations in proportioning raw materials for cement clinker are the potential compound composition the percentage of Hquid phase at clinkering temperatures and the bumabiUty of the raw mix, ie, the relative ease, in terms of temperature, time, and fuel requirements, of combining the oxides into good quaUty clinker. The ratios of the oxides are related to clinker composition and bumabiUty. For example, as the CaO content of the mix is increased, more C S can be formed, but certain limits cannot be exceeded under normal burning conditions. The lime saturation factor (LSF) is a measure of the amount of CaO that can be combined (20) ... 

Hicks and Dorn (1982) recommend the Ono test (except birefringence) once per day and every time a change is made in the burning process and, once per week, a polished-section examination of the 0.84- to 0.59-mm (No. 20- to 30 mesh) granulated clinker. 

Ono s method and theory of kiln control were introduced to the Western world by Mau (1975). In that same year Ono conducted a seminar for North American cement-company personnel in Hawaii, where he taught the details of his theories and method of kiln control with powder-mount microscopy. The dissemination of Ono s technique to the Western world was largely due to this seminar. Since that time Ono s theories and method of clinker interpretation have been subjects of research in laboratories of many North American cement companies, the Portland Cement Association, and in Europe. Mau (1979) reported on the routine application of the Ono technique in Hawaii and strongly supported Ono s Method and theories, stressing their use to control burning temperature. 

The crystal lattice constants of alite (a,b,c) and unit cell volume (V), determined by XRD, were studied in relation to alite double refraction (Ono, 1984). Alite with high double refraction was characterized by long a and short b and c, V was decreased, and (a/bY was large. Laboratory-prepared alite, burned at high temperature for a long time, had a small V, large (a/ bY, and a high double refraction. Therefore, XRD can be used in much the same way as the microscope in the quality control of clinker. 

Increasing clinker size Higher burning temperatures and larger amount of liquid phase more time for nodulation (Eby, 1985)... 

Dusty clinker, coarsely crystalline silicates, low-porosity nodules, poor grindability Slow temperature rise, higher clinkering temperature, longer time in burning zone and transition zone (Wolter, 1985)... 

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