Method for Clarifying Slimes.
U S Pat 4 295 971 1981 Oct; :
Slimes and other wastewaters containing negatively charged particles are clarified by flocculating with positively charged dodecylamine stabilized magnetite colloid. The flocs are separated by gravity or by the use of a magnetic field. For example, fecl2.4H2o and fecl3.6H2o solutions were combined to give a fe(III)-fe(II) molar ratio of 1.3:1, Nh4oh was added as precipitant, and the resulting precipitate was settled on a permanent magnet, separated, washed with nh4oh, settled on a permanent magnet, and decanted. Dodecylamine was then added to the precipitate and the mixture adjusted to a volume such that the composition had a saturation magnetization of 5 g. The dodecylamine content was 25 pct based on the magnetite. When 1.0 Ml of the composition was added to 100 ml of iron oxide slimes having a solids content of 0.035 pct and a turbidity reading of 59 nephelometric turbidity units (ntu), the ntu reading of the resultant supernatant was 5.5.
U.S. Pat. 4,295,971, Oct. 20, 1981; Chem. Abstr. 95:191,956K