Continuous high-intensity mixing of two fluids for carrying out fast precipitation is an important method for producing nanoparticulate solids for diverse applications, e.g., in fine chemistry, pigment or catalyst preparation. Continuous precipitation with a newly developed micromixer technology, the so-called valve-assisted micromixer, allows for stable operation without clogging for several days. Scale-up to technically relevant scale was achieved without differences in the quality of the precipitate. The technology has been extensively tested for preparation of catalysts for production of carbon nanotubes.