Coming into Compliance Using Vacuum Distillation
The Drawn Metal TubeCompany is nestled in the hills of western Connecticut. A small river ripples through the town of Thomaston, just along side the company's 40-plus year old building. Salmon and bass swim in the river, but just a few short years ago the river was virtually dead.
This was not the fault of The Drawn Metal Tube Company, but a host of industries along the river. The state of Connecticut decided to clean up the river and levied regulations limiting effluent from those industries. This affected the cleaning and pickling line at The Drawn Metal Tube Company.
Cleaning the copper and nickel/silver tubing involves sulfuric acid and a bright dip, along with rinses. "We used to dump the cleaning solutions into the river after treatment. We had a permit to do this," stated Gerard Chausse, vice president of production.
"But the EPA decided it wanted stricter effluent limits, so we began exploring ways to comply," Mr. Chausse noted.
The Drawn Metal Tube Company chose a vacuum evaporation system from Calfran International, Inc. The cold evaporation system works under a vacuum with a refrigeration unit that boils water at 80 to 90F.
Rinse water enters the system at a pH of 8.2 to 8.5. After processing, pH is 7.2 to 7.5. During the process, distillate rises to the top of the chamber and solids remain on the bottom. The clean distilled water is returned to the cleaning line at a rate of 1/2 gpm. The system has the capacity to process 600 gpd.
Periodically, the sludge on the bottom is automatically pumped into another tank. This sludge is boiled down further under the same type of operation. The granular sludge is then shipped off site for reclamation of the metal values.
The company is exploring the possibility of putting in a smaller Calfran unit for the rinses after the copper bright solution. This unit processes 50 gpd. "Pumping the rinses through a single unit would allow us to recover the copper and water and reuse both in a fresh batch, saving money on the long run," stated Brian McAdams, maintenance supervisor.
The cleaning line also features counterflow rinse tanks. Fresh water is added occasionally to make up for evaporation due to open air. This amounts to approximately 300 to 500 gal per week.
Installing the vacuum evaporation unit has saved The Drawn Metal Tube Company money and also helped save the river. Mr. McAdams can tell you that. He catches bass and salmon in it regularly.