Cement, Energy and Environment

the fully automated and nearly maintenance– free silo discharge. Downstream bulk loading silos are fed via a bucket elevator. Flat storage terminals are best suited for medium to long tern service. Most common storage capacities range from 10 000 up to 25 000 t. This is a low cost solution, especiallywhen an existing warehouse building can be converted into a material storage installation or when the buildings later need to be used for other purposes. Courtesy : World Cement, Mar. 02, Pp. 75-86, Enquiry no. 9. Email: mail@worldcement.com Web: www. worldcement.com Fax: +44(0) 1252 718992 RESISTING WEAR EROSION Pankaj fain, Wearesist Technologies Pvt. Ltd., India. In a cement plant a major chunk of the energy bill is from power consumed by cement mill grinding. Cement original equipment manufacturers (OEM) have been continuously upgrading technology to reduce power consumption. One of the bes t commercia l technology developed for achieving this is a combination of high pressure rolls known as the roller press. Actual experience has shown that for a cep1ent unit of 1180 tph cappcity, a mill circuit consumes approximately 33 units of same capacity mill only 27 units of power per t of cement will be used by a roller press. This implies a power saving of 6 units of power per t of cement produced. Another advantage of using this concept is that once coupled with conventional tube mill the output can be more than double. The third advantage is in the reduction in the cost of maintenance or downtime of the mills. For example, the cost of mill liners/ t of cement produced, weighs in favour of the roller press. The wear in a roller press toll is a three body abrasion characterised by body and counter body, the material bed in between and the ambient medium, i.e. air. However, on close inspection, two different wear systems seem to be working in area I and II respectively, as follows: + Wear systemI: Due to the rnaterial column located above the roller gap, the surface of the roller faces abrasion while the circumferential movement of the roller takes place. + Wear system II: while rotating at a certain angle and type of feed stock, the mineral particles are gripped and drawn into the gap between the rollers. During this process the splitting strength on many particles is exceeded so that they suffer fracture or breakage. In this case there is no movement of particles, or abrasion involved, but compressive load is very high. Surface removal is achieved by micro fatigue causing minute surface areas to spall off as a result of repeated deformation or stress. The various types of roller body were designed on rolls, welding technology is used according to the following specifications: + Forgings require a we ld overlay of approximately 12 mrn thick, which is a crack free alloy with carbide concentration lower than 20%. The surface is then profiled by using a variety of methods to improve the output.