Nachfällung = postprecipitation
(Chemie und chemische Technik - Deutsch - Englisch - VEB Verlag Technik Berlin)

postprecipitation (plural postprecipitations)
(chemistry) The precipitation of a second (often related) substance upon the surface of an initial precipitate
https://en.wiktionary.org/wiki/postprecipitation

Postprecipitation results when a solution contains two ions, one that is rapidly precipitated and another that is slowly precipitated by the precipitating agent (Kolthoff et al., 1969). The first precipitate is usually
contaminated by the second one.
http://www.orau.org/ptp/PTP Library/library/Nrc/Nureg/1576v2...

After centrifugation, the pellet was washed 5 times with PBS. The washed pellet and pre- and postprecipitation samples of the glomerular extract were boiled in SDS sample buffer containing dithiothreitol for 5 minutes and centrifuged, and 10 μL of each supernatant was subjected to SDS-PAGE using 7.5% or 5% gels.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC409863/

The method of Claim 4 further comprising a postprecipitation step of adding a basic solution to the precipitate to raise the pH to 910 thereof, . to precipitate soluble magnesium.
http://www.sumobrain.com/patents/wipo/High-density-antacid-p...


--------------------------------------------------
Note added at 1 hr (2015-07-02 13:33:10 GMT)
--------------------------------------------------

Apologies, it should be of course "post[-]precipitations".