2005-12-02_REVISION - M1977208 - Laserfiche WebLink

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ATTACHMENT No. 1 CEMEX, Inc. Lyons Facility C-Pit Water Neutralization with Consumptive Use Pumping Summary The CEMEX Lyons facility generates cement kiln dust (CKD). Some is returned to the process, while excess is transferred it to the former C-Pit quarry for disposal. The C-Pit has been collecting water from various sources in the local vicinity of the pit. Due to the inherent characteristics of the CKD and its contact with water accumulating in C-Pit, the pit water has become alkaline (pH=12) and concentrated with various constituents. Under prior Technical Revisions to its mining permit, CEMEX attempted to eliminate the water in the C-Pit by blending it with A-Pit water and using the combined flow within the cement manufacturing process at the spray tower that cools the gasses exiting the kiln. The thinking at the time was that the poor quality water in C-Pit could be diluted with A- Pit water sufficiently to be acceptable for use in the spray tower. Approximately 70 gpm C-Pit water was combined with 100 gpm A-Pit water. This mixture proved to be operationally problematic due to excessive scaling in the piping, downstream of the mixing point; the accumulation of precipitated sludge in the spray tower feed tank to the spray tower; and scaling at the nozzles in the spray tower. Subsequent testing and analysis indicated that the scaling and precipitation were caused by interaction between A-Pit and C-Pit waters. Blending the waters from the two pits resulted in a reaction between calcium in A-Pit water and high pH constituents of C-Pit water. The result was precipitation of calcite. CEMEX proposes to modify the approach and eliminate the problem by feeding the spray tower with C-Pit water exclusively, since it contains very little calcium. To prevent scaling, CEMEX will reduce the pH of the C-Pit water before reuse. By using C-Pit water without dilution with A-Pit water, scaling can be avoided. In addition, the C-Pit water pumping rate will be increased to 170 gpm, so it will be used faster. The proposed neutralization system is based upon the in-line addition of sulfuric acid, which will reduce the pH to a level where excessive scaling is prevented in the feed tank and spray nozzles. This will be accomplished by adding 20% sulfuric acid at approximately 0.4 gpm via avariable-speed acid feed pump to the estimated 170 gpm being pumped from the C-Pit. The C-Pit pump presently on order by CEMEX is rated at 50 horsepower, 120 psi, and capable of delivering 250-300 gpm. Acid will be stored at the site in a 6,500 gallon double-walled polyethylene tank. An in-line static mixer installed downstream of the acid feed location will ensure proper mixing. After mixing, the combined flow will be measured using an in-line totalizing flowmeter. The neutralized C-Pit water will be discharged to the feed tank at the base of the cooling tower, and a second pump will inject the water into the process at the top of the spray tower. The pump and acid feed system will be controlled remotely by CEMEX