About Us : Case Studies : Closed-Loop Alkaline Recycling Proves an Award Winning Application

Closed-Loop Alkaline Recycling Proves an Award Winning Application
by Tim Keiper and John F. Russo

A Closed -loop chemical recycling system not only improved product quality and lowered costs for a company-it won their team of engineers an award. The six engineers of the "Stain Team," headed by Tim Keiper of Instrument Specialties Company Inc (Delaware Water Gap, Pa), earned the company's Continuous Improvement Pioneer Award after reworking their cleaning operation to include an AquaChemical TM AC002012 recycling system from Separation Technologists, Inc. (Methuen, Mass).

One process conducted at Instrument Specialties is a degreasing operation, where parts are cleaned prior to electroplating. The parts themselves are beryllium copper strips used in shielding equipment for computers and other electronic devices (figures 1 &2). The parts washer runs at a temperature of 170 degrees F. The contaminants being removed from the parts include water-soluble stamping oils, suspended solids, and metal particles. Prior to implementing the new recycling system, a coalescer and skimmer were the only oil removal methods used in the operation.

The company used a chemical cleaner to remove oil from the parts. A problem arose when small amounts of oil were detected on the parts after cleaning, which led to quality issues. The team of engineers researched and installed the Aqua-Chemical membrane-type, closed-loop chemical recycling system to remove the contaminants and then concentrate them for disposal.

The Stain Team expected to improve product quality, which was the initial goal. But in achieving that goal, they realized significant other benefits as well.

Prior to purchasing the recycling system, Instrument Specialties employed a cleaning operation whereby 600 gallons of cleaning solution was changed every two to three days; this was done in an effort to maintain quality. Despite these efforts, spotting continued to be a substantial problem, creating bare spots and poor adhesion. Indeed, it was the key cost factor in postcleaning plating part failures.

The company paid a high cost for their inefficient cleaning system, not only in terms of buying new chemicals, but in waste haulage and disposal. And, even with all the changeover and expense, the desired quality still wasn't being achieved.

Revamping the Whole Process
The Stain Team began by working with Separation Technologists to examine the full scope of the problem and find its cause. A pilot study was conducted on the cleaning solution used in Instrument Specialties' operation. Results suggested several problematic facets-not only in the chemistry, but in the entire cleaning process.

Neither the coalescing nor the skimming mechanism was capable of removing significant amounts of the emulsified oil from the cleaning system. The oil could therefore redeposit on the parts. The research team determined that installing the AquaChemical recycling system would solve this problem. The emulsified oil could be easily removed by mechanical means- without using special chemicals to achieve oil separation.

The Stain Team, in conjunction with Separation Technologists and a new chemical supplier Matchless Metal Polish, developed an alternative cleaning solution for use with their prospective recycling system. The new chemistry, could be close-loop recycled to remove the free and emulsified oil that lingers on parts after washing.

This new cleaning chemistry (Matchless Metal Polish, SC-114-L) is a milky alkaline, highly wetted, liquid non-stretch soak cleaner that is effective as both a soak and an ultrasonic cleaner. It effectively removes oil and soil from aluminum, zinc die-castings, brass, and steel without attack on the base metal and can be used in soak tanks, agitating parts washing equipment, and ultrasonic units. It is compatible with microfiltration and boasts a wide operating temperature range.

The new chemistry has very free rinsing properties and a high soil tolerance. Its mild alkalinity also prevents parts from discoloring. The new solution is more potent, resulting in better cleaning effectiveness, and demonstrates a 35% reduction in comparable cost over the old chemistry.

Reaping the Rewards
Currently, the concentration of the cleaner ranges from 2% to 5%, and 0.3 gallons of chemistry are added on a daily basis to makeup for chemistry dragout and undesired membrane removal of some of the cleaning chemistry. The membranes are cleaned every alternate day and have never been replaces in nearly one year of operation. Reductions in chemistry use, physical labor, waste disposal, and product rejects have led to an annual cost savings of almost $120,000. The typical components of the waste stream include water-soluble oil and suspended solids, which are hauled away for disposal.

The changeover of cleaning material, which was every two to three days, has become once every six to eight weeks. During changeovers, the 600 gallons of used cleaning solution is evaporated, and the concentrate is hauled away along with the remaining waste oil. This considerable extension in working time means tremendous savings in cleaning solution costs, since each batch has eight times the working life of the old. Similarly, haulage and disposal costs have been reduced proportionately, as has system maintenance. With continuous recycling, alkaline chemical spikes have been eliminated, resulting in a more consistent concentration of chemistry.

The most significant achievement, of course, is the one first targeted by the Stain Team: a total improvement in the quality of cleaning for the finished product. "We are very close to a stain-free (defect-free) product," stated Keiper. "The reduction of downtime in the process has also helped in providing a benchmark of completely elimination stains in all of our products."

New Technology + New Chemistry = Success
The key to the Stain Team's success lies largely with their implementation of the AquaChemical technology and the Matchless Chemistry. The closed-loop, membrane-type system has proven a valuable means of extending the working life of the solution - and efficiently separating clean, usable solution - well beyond the limits of previous technology. It has also simplified the Instrument Specialties Company's operation.

"Holding tanks have been added to stop the time-consuming transfer of used solution via drums, a time savings of approximately 75 percent," Keiper remarked. "The procedure is now automated, saving time and eliminating the chance of spillage."

For more information about the AquaChemical system, or other closed-loop wastewater treatment, recycling, and purification systems, contact Separation Technologists Inc at (978) 794-1170, Fax (978) 794-0933. For more information about the Matchless chemistry, contact the Matchless Metal Polish Company at (800) 328-5436.

Reprinted from Parts Cleaning magazine May 1999
© 1999 Witter Publishing Corporation