Recirculation of Mass Finishing Process Solution
How can we recirculate our process fluid without discharging to drain?
Q. We are currently running a 10-cubic-foot vibratory machine with a fast-cut ceramic wet process media. How can we recirculate our process fluid without discharging to drain?—C.B.
A. A proper recirculating system works well. There are important considerations when designing your system:
- The correct tank size, type and filtration,
- A media that cuts but produces very little sediment,
- The proper soap formulated for recirculating,
- Timely discharge of fluid to a flocculent system for reuse or to an evaporator for elimination.
Our recommendation for your 10-cubic-foot vibratory machine is to use a two-baffled, three-compartment, stainless, 150-gallon tank with a bag filter on the inlet and a cartridge-type filter with 50-micron filters on the outlet. A float activated diaphragm pump should be used in the third or last compartment to pump the fluid back to the vibratory machine. Note: the inlet of the recirculating tank must be below the outlet of the vibratory machine; if not, a small 12 x 12 x 18-inch transfer tank with a float pump must be added after the vibratory machine to pump the fluid up to the inlet of the recirculating tank.
Change your media to a high-density cut ceramic that lasts four to five times longer than a standard fast-cut, reducing the sediment buildup in your tank by 75 percent. The recirculating tank has to be periodically cleaned out (once or twice a month), so the less sediment the better.
Select a soap formulated with a biocide to reduce odor. The soap must be designed to run through the system 12 to 14 times before breaking down. So if you’re running 10 gallons though the vibratory machine an hour with the 150 gallon tank, your solution should be changed out at approximately 200 hours. The fluid can then be flocked for reuse, evaporated or collected by companies that pick up gray water. Cost of disposal is eight to 16 cents per gallon.
Many manufacturing plants are built today with no drains, eliminating discharge of any fluids. There are also plants operating with septic systems and companies in very strict sewage districts. These plants are good examples of where recirculation of mass finishing fluids will work well.
Choice of equipment, media and compounds has a major impact on your finishing applications.
When choosing vibratory media, understand the size, shape, starting roughness condition and metallurgical structure of the part.
The correct peripheral speed is an important consideration in getting the right results from your buffing operation. A buff that is turning too fast or too slow may result in damage to the buff or to the workpiece.