Download Full Text (593 KB)


Scale-forming metal oxides and carbonates, such as cupric oxide, can be precipitated from an ammoniacal leaching solution with minimum scale buildup by distilling the solution in an externally heated distillation chamber mounted for rotation about a generally horizontal axis. The distillation chamber includes a plurality of axially spaced annular baffles defining a plurality of compartments containing a tumbling medium, such as spherical balls. The solution is continuously introduced into the inlet end of the chamber and heated under pressure to a temperature above its boiling point as it flows over the baffles toward the outlet end of the chamber. A slurry containing the precipitated cupric oxide is continuously withdrawn from the outlet end and the evaporated gases are continuously withdrawn from the inlet end. The balls rub against each other, the interior of the chamber, and the sides of the baffles, as the chamber is rotated at a non-centrifuging speed, to provide a grinding or scrubbing action which minimizes a scale buildup of the precipitating cupric oxide.

Patent Number



Board of Control of Michigan Technological University, Houghton, Mich.

Application Number


Date Filed


Certificate of Correction


Issue Date



Engineering | Materials Science and Engineering


For the most up-to-date information about this patent, including the availability of Certificates of Correction, be sure to check the United States Patent and Trademark Office's free, publicly accessible database: Patent Public Search

Precipitation of scale-forming materials from solution



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.