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//CC-MEX July 10, 2012 Mr. Fionn 0' Neill - Director of Operations Kleen Industrial Services 50 Oak Court# Suite 210 Danville, CA 94526 Re: Recycling Spent Abrasives Dear Mr. O'Neill: In response to your request concerning the recyclability of spent abrasives such as copper slag, garnet, aluminum oxide, silica sand, and steel fines in the manufacture of Portland cement clinker, CEMEX has the capacity and desire to use these materials as they are produced. Spent abrasives such as copper slag, garnet, aluminum oxide, silica sand, and steel fines (as a spent blast grit or as a waste product from the generators) is used in the Portland cement manufacturing process as an ingredient for both the high iron oxide (Fe203) and alumina oxide (AI203) content of spent materials. Since basting abrasives such as copper slag, have already been heated, there is no additional CO2 to liberate. Therefore, the CO2 produced per ton of cement will decrease. Replacing raw feed with spent abrasives also eliminates the need to quarry raw material, reducing additional CO2 emissions. Portland cement is made from raw materials rich in the oxides of calcium, alumina, iron, and silica content. These materials are proportioned and ground into a fine mixture called "'raw mix" this mixture is then sintered in a kiln at temperatures in excess of 2700° F. In the kiln the "raw mix" melts and forms "clinker," this clinker exits the kiln and is air cooled. The cooled clinker is then ground with gypsum to produce Portland cement. Due to the large number of oxide rich materials that may be available throughout the United States and the world there is no set of national standards or specifications that regulate the use of spent abrasives such as copper slag or any other ingredient(s) as raw materials in Portland cement kilns. This does not mean that Portland cement manufacturing is without standards or specifications. Cement manufactures often have a set of internal standards or specifications for the quality of the raw materials. The reason for this is that each Portland cement kiln uses raw materials from varying sources or deposits. Making the formula for each Portland cement kiln unique owing to the differences in oxide concentrations found in their raw material sources (quarry). Portland cement product standards are set forth in ASTM C-150. This standard or specification has been around in its present form (more or less) since 1940. Prior to C-150, ASTM had other specifications for Portland cement dating back to ASTMS founding in 1889.