Continuous Precipitation of Nickel Hydroxide by Addition of Ammonium Ions

• Published in: Crystal growth & design 2016-04, Vol.16 (4), p.1824-1828
• Main Authors: Funakoshi, Kunio, Yoshizawa, Shogo, Matsuoka, Masakuni
• Format: Article
• Language: English
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.5b00950

Spherical and dense nickel hydroxide, Ni­(OH)2, particles are produced by addition of ammonia or ammonium ions, NH4 +, using a continuous precipitation. In this study, the nickel ion, Ni2+, concentrations and the NH4 + concentrations in a suspended solution for the continuous precipitation of Ni­(OH)2 are examined, and the formation behaviors of spherical and dense Ni­(OH)2 particles are discussed by the relations between the Ni2+ and NH4 + concentrations. When NH4 + was supplied into a suspended solution during the continuous precipitation of Ni­(OH)2, Ni2+ was present in a steady state and the Ni2+ concentrations changed with the NH4 + concentrations in a feed solution, with the solution pH and the residence times of suspended solutions in a crystallizer. The ratios of the NH4 + concentrations to the Ni2+ in a solution at steady state were different from the coordination number of NH3 in a nickel ammine complex. Formation of Ni­(OH)2 precipitates when adding NH4 + is discussed by the relations between the Ni2+ and the NH4 + concentrations in suspended solution for continuous and batch operations.