Laserfiche WebLink
Banks and Gesso, LLC <br />necessary proportions of calcium, silica, iron and alumina for creating the calcium <br />silicates that are the active ingredients in Portland cement. Crushed limestone, shale <br />and sandstone are precisely metered into ball mills which pulverize it fo a fine powder <br />called raw or kiln feed. The kiln feed is introduced to the preheater/precalciner that <br />heats the material to over 1550 degrees F, calcining it (turning it to lime), using a <br />combination of waste heat from the kiln and additional fuel. This calcined material is <br />then fed into the rotary kiln. The rotary kiln is a 245 foot long, 14.5 foot diameter rotating <br />pipe. It is an effective mixer, conveyor and reaction chamber. Material is gradually <br />heated from 1550 degrees F to over 2600 degrees F. During this process the lime turns <br />to cement clinker with all the chemical properties of the finished product. Cement clinker <br />is typically a black granular material with the consistency of gravel. <br />The clinker from the kiln is metered into the finish mill along with a small fraction of <br />gypsum. The finish mill is a ball mill that pulverizes the clinker and gypsum into a very <br />fine powder that is the finished product - Portland cement. <br />A combination of fuels is used in the Lyons preheater/precalciner and kiln system. Coal <br />and natural gas have been the most common. Tires and other materials have also been <br />used. The fuel choice is based on a combination of the fuel's cost and chemical <br />composition. <br />' Tire Derived Fuels are totally consumed in the kiln process. Most of the tire volatilizes <br />and bums within seconds (15 to 20 sec) in the precalciner. Any remnants (mainly steel <br />cords and bead) fall into the kiln and are combined with the feed to produce clinker. <br />' There is no ash or residue attributable to tire combustion. In the case of a process <br />upset, tire feed would be interrupted along with other fuels as soon as a critical failure <br />would be detected by the process computer. The kiln system would be shut down in a <br />' pre-established auto sequence. Typical situations that could cause this type of <br />shutdown would be the failure of kiln feed pump or compressor or induced draft fan. In <br />these situations, the failure is corrected and the kiln restarted. TDF will only be used <br />during steady state operation on the kiln. It will not be used during warmup. Natural gas <br />is currently the only fuel used during warmup until stable process conditions are <br />established. After this point, coal is added and in the future, the tire feed would begin. <br />Material contained in the kiln and vessels at shutdown remains in the process. It <br />becomes good cement product after the kiln is restarted. <br />A mass balance diagram is attached. <br />5.0 November, 2002 Trial Burn <br />Cemex, at the request of the Boulder County Health Department, designed a five day <br />trial tire bum for late November 2002 (The trial burn was from approximately November <br />1 S through November 22, 2003). The plan was approved by the State and County <br />Health Departments (and representatives of State and County Health Departments <br />observed the trial bum). <br />The plan included extensive air emissions testing and duplication of representative <br />operational conditions. Tires were used as approximately 19% of the fuel (on a BTU <br />basis) and were fed into the kiln at a rate and using a technique that is identical to the <br />planned operational practice. <br />J <br />~~~,~~ <br />02053 Cemex, Inc. CKD Testing 3 <br />