Phosphoric Acid Plant Upgrade
Rhodia, Coatzacoalcos, Mexico

KEMWorks Technology, Inc. assisted Rhodia in Coatzacoalcos, Mexico in the upgrade of their phosphoric acid plant to improve production, increase efficiency and meet new environmental guidelines. KEMWorks provided the basic engineering package for the client to submit to their detail engineering firm.

The project included a condensate recovery system, a sludge recycle system from the clarifiers, and conversion from once through cooling water to a recycled pond water system. Rhodia previously used saline water for both direct and indirect cooling. The new system included conventional cooling towers for the indirect heat exchangers and towers operating with contaminated for direct contact coolers.  This water is also used to carry the gypsum waste product out to the disposal area.  The gypsum slurry and return water system was included in the project.

The GTSP plant was also involved since the once through scrubbers must be put on a recycled system, to minimize the water usage. A cake wash system was added to provide hot water to the filters where cold water is currently used. Containment of all process water and purges was part of the project in order to minimize the water discharge and to improve recoveries. The discharge water is treated in a new double liming system.

Another task was the conversion of the present control system in the phosphoric acid plant to a new DCS system. Instrument specifications and control philosophy were provided by KEMWorks.

Project Highlights:

• Condensate system and Cooling towers for purified acid plant are operational.
•  After chlorides have been leached from stack, pond water will replace freshwater as cake wash.
•  Additional studies are in progress to improve efficiency production and develop new products.
   

More details of the project can be read in the paper "Wastewater Recycling Project at Rhodia, Mexico" by Christopher Earl, presented at AIChE Clearwater Convention, June 16, 2001.