Nickel hydroxide and method for producing same
View Patent ↗A process for preparing nickel hydroxide by alkaline precipitation from nickel salt solutions in the presence of complexing agents, in which the precipitation is carried out at at least two different locations in the same mother liquor with different precipitation kinetics at the different locations and the mother liquor is mixed prior to agglomeration of the precipitated primary crystals, is described.
1. Process for preparing nickel hydroxide by alkaline precipitation from nickel salt solutions in the presence of complexing agents, wherein the nickel salt solutions are introduced into a mother liquor via several spatially separated inlets in such a way that precipitation takes place in at least two different locations, with different precipitation kinetics, in the mother liquor and the mother liquor is stirred prior to agglomeration of precipitated primary crystals.
2. Process according to claim 1 , characterized in that the different precipitation kinetics are produced by different nickel ion concentrations, different alkali metal hydroxide concentrations, different concentrations of complexing agent, different temperatures, different rates of mixing with the mother liquor and/or different concentrations of metal ions other than nickel.
3. Process according to claim 1 , characterized in that nickel-ammine complex solutions [Ni(NH 3 ) n (H 2 O) 6−n ] 2+ are introduced into an alkali mother liquor, with solutions having different mean degrees of complexation n being introduced at different locations.
4. Process according to claim 3 , characterized in that the different degree of complexation n is produced by different temperatures and/or different Ni/NH 3 ratios of the solutions.
5. Process according to claim 1 , characterized in that a nickel salt solution and an alkaline solution are introduced at each of the different locations and the alkali metal hydroxide concentrations of the alkaline solutions are different.
6. Process according to claim 5 , characterized in that the nickel salts solutions and the alkaline solutions are introduced concentrically.
7. Process according to claim 1 , characterized in that trivalent ions having ion radii, which differ greatly from that of Ni, and which are selected from the group consisting of B, Al, In, Tl, Sc, Y, La, lanthanoides and Bi, are used in amounts of from 0.1 to 3% by weight based on Ni as metal ions other than nickel.
8. Process according to claim 1 , characterized in that at least an inlet point is provided with a flow tube so that only mixing with a locally screened part of the mother liquor occurs initially.
9. Process according to claim 1 , wherein the process is carried out in the presence of increased turbulence at least one inlet point.
10. Process ac cording to claim 1 , characterized in that divalent dopants selected from the group consisting of Co, Zn, Mg, Ca, Sr and Ba are incorporated into the nickel hydroxide in amounts of from 0.3 to 7% by weight.
11. The process according to claim 1 , wherein the nickel hydroxide has at least a bimodal primary particle size distribution.
12. The process according to claim 1 , wherein the nickel hydroxide has a multimodal primary particle size distribution.