Clinker formation

Clinker treatments are additives designed to reduce the amount of clinkering formations that takes place in boilers fired by bark, bagasse, and similar low-calorific-value fuels. These fuels can give rise to considerable amounts of noncombustible deposits that must be continuously or regularly removed from the furnace area. Clinker treatments are formulated for use with various types of furnace, including slant, pin hole, and chain grate furnaces. 

When coal is burned in a combustion unit, mineral matter undergoes major changes that lead to problems of clinker formation, fly ash, slagging, and boiler tube corrosion. The efficiency of a combustion unit is related to the amount of ash produced, since it is a diluent. On the positive side, ash has been utilized as a construction material and is a possible source of refractory materials, as cement additives, or as adsorbents for gas-cleaning processes. However, the composition of the ash must be known before it can be utilized in this way. 

Clinker formation in the Ca0-Al203-Fe203-Si02 system... 

Another calcium silicate fluoride, cuspidine [Ca4(Si207)F2], exists but is not formed under conditions relevant to clinker formation. Systems containing fluorosilicate ions [SiF ] and the possible use of calcium fluorosilicate as a flux have been investigated (S16). 

Minor or trace components derived from raw materials, fuel, refractories or other plant materials, or added deliberately, can affect the reactions of clinker formation, or the properties of the product, or both. Their effects can be beneficial or harmful. Beneficial effects include acceleration of the clinkering reactions or lowering of the temperature at which they occur, or increase in the reactivity of the product leading to more rapid strength development. Harmful effects include decrease in alite content, volatilization in the kiln with consequent formation of kiln rings or other deposits, decrease in the durability of concrete made with the cement, or the introduction of poisonous elements. Some elements have beneficial effects at low concentrations and harmful ones at higher concentrations. Bucchi (B33,B28) reviewed some of the effects on the manufacturing process. 

Flame formation must be favorable to a dense, stable coating on the brick refractory lining in the burning zone of the kiln as well as to a nodular clinker formation with low dust content and correctly developed clinker phases. 

In the rotary kiln the process of rrraterial nodulising, parallel to clinker formation is occiuing. The studies have shown thatfor nodulising the siuface tension of clinker melt is very importarrt and its rise has advarrtageous effect [38]. It is shown on Fig. 2.41. 

Burki, P., and Braun, H., "Investigations on the Influence of Raw Mix Reactivity and Rate of Upheating upon Clinker Formation," 8th International Congress on Chemistry of Cement, Rio de Janeiro, Brazil, 1988, pp. 56-61. 

Butt, Y.M., and Timashev, V.V., "The Mechanism of Clinker Formation Processes and Ways of Modification of Clinker Structure," Sixth International Congress on the Chemistry of Cement, Sec. I, Moscow, 1974, pp. 3-74. 

Chromy, S., "Process of Portland Clinker Formation, Reactivity, and Burnability of Cement Raw Materials Part I Mechanism of Portland Clinker Formation," Zement-Kalk-Gips, Vol. 35, No. 4, 1982, pp. 204-210. 

Gartner, E.M., "Physical and Chemical Aspects of Portland Cement Clinker Formation," Research on the Manufacture and Use of Cements, Proceedings of the Engineering Foundation Conference, Henniker, New Hampshire, 1985, pp. 1-20. 

Imlach, J.A., and Hofmanner, E., "Investigation of Clinker Formation by DTA and Optical Microscopy," Sixth International Congress on the Chemistry of Cement, Supplemental Paper, Sec. 1,1-5, Moscow, 1974,11 pp. 

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