A practical limestone charging system
for avoiding segregation in large shaft kilns
L. Sarandrea, V. Colombari, CimprogettiSrl, Dalmine, Italy
Lime sales in recent years have been increasingly dominated by stricter demands on product quality and costs with respect to specific energy consumption and the use of crushed limestone with a wide size spectrum. Parallel Flow Regenerative kilns are now used very widely throughout the world for producing lime. As a leading provider of this type of kiln Cimprogetti recently introduced the Vanguard high performance lime kiln to the lime industry with daily outputs of up to 700 t/d. Since then the company has been constantly concerned with gathering information about the choice of limestone and the process engineering aspects of kiln design with the aim of using limestone with the widest possible size range, improving the fuel distribution and preventing material segregation. A suitable material charging system has been developed to improve the kiln process, especially with respect to large kiln units. A new scientific approach for technical evaluation of the existing kiln charging system was started in conjunction with Italian universities in which the size composition of the raw limestone is included in the analysis. The investigations were carried out using Rocky-DEM, a 3D Discrete Element Modeling (DEM) software. The following information was obtained: the newly developed kiln charging equipment is less complicated and involves lower maintenance costs; reduced use of chutes within the charging system can minimize segregation of the material; generation of dust is substantially reduced by consistent use of the enclosed charging system; the new kiln charging equipment can also be used with existing lime kilns that exhibit critical segregation behaviour and must be optimized with respect to the quality of lime produced.
Summary CEMENT INTERNATIONAL 03/2016 pp 66-72
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