Recycling Synthetic Machine Coolant
The principle behind the treatment is that synthetic coolant is soluble in water, as opposed to semi-synthetic or so-called "soluble oil", which in fact is a stable emulsion of oil in water. Materials that are soluble in water will, in general, pass through an ultrafiltration membrane, whereas materials that form a colloidal suspension or are emulsified in water are retained by this membrane. In general, the rule is that whatever makes water cloudy will be removed by an ultrafiltr ation membrane.
In use, machining coolants become contaminated with a combination of tramp oils which arise from hydraulic oils and way lubes from the machining equipment and bacteria, as well as metal particles from the machining operations. Eventually, this causes the coolant to be discarded, since it will no longer perform adequately.
By subjecting this spent material to an ultrafiltration membrane, the contaminants are retained, while the coolant passes through the membrane, and can then be reused.
The complete system consists of a transfer pump to transfer the waste fluid from a storage tank to an oil/water separator. At this point, any free or floating oil is removed. The fluid then passes to a process tank. From here, it is pumped at high velocity and under pressure (70 to 90 psi) across the surface of the ultrafiltration membrane. Dynatec Systems uses a wide channel membrane configuration, since this allows for minimal prefiltration prior to treatment.
The recovered coolant passes through the membrane, while the contaminants are returned to and concentrated in the process tank for periodic disposal. After some minor testing is completed to ensure the recovered fluid's quality, it is available for reuse.