The Sherritt ammonia leach process uses ammonia to increase the solubility of NiS(s). The solubility product (Kps) of NiS in water at 25C is 4.0 x 10-. Atomic weights: Nitrogen = 14.01; Hydrogen = 1.008; Nickel = 58.71, Sulfur = 32.06. OBS.: present the equations, formulas and accounts to reach the final results.

(a) How many grams of NiS are dissolved in 1L if the concentration of NH in solution is 130g/L? (Assume nickel is present in the solution as Ni+ and Ni(NH)+. ( for Ni(NH)+ = 1.20 x 10. Assume activities in the solution equal to molarity, M). What is the concentration of nickel in the solution in g/L?

(b) By what factor does the presence of ammonia increase the solubility of nickel sulfide?

(c) If oxygen is added during ammonia leaching to reduce [S-] in solution to 1x10- M, does the concentration of nickel in solution increase or decrease? How many times does it increase or decrease compared to leaching with ammonia without oxygen? (Assume that S- oxidizes to SO- and that nickel sulfate is highly soluble.)