TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Compounds: Compounds (I) with a D50 value of less than 3 microns, a tap density to D50 ratio of at least 0.6 (preferably at least 0.8) g/cm3/micron, a BET surface of at least 5 (preferably at least 10) m2/g, and a standardised particle size range (D90/D50) of at least 1.8 (preferably at least 2.0). The particles are spheroidal, with a form factor of at least 0.8, preferably at least 0.9.Preferred Method: The suspension in stage (c) shows a solid content of at least 300 g/l and the alkali concentration is at least 0.25 mol/l; the power input in stage (b) is at least 2.5 W/l. EXAMPLE - Mother liquor containing 133 g/l sodium sulphate, 10 g/l sodium hydroxide and 11 g/l ammonia was heated to 50 degrees C in a stirred (1000 r.p.m.) reactor with a circulating pump (10 m3/h), treated (from separate pumps) with 22446 g/h metal sulphate solution (79.91 g/l nickel; 20.06 g/l cobalt), 16572 g/h sodium hydroxide solution (200 g/l NaOH) and 1512 g/h ammonia solution (225 g/l NH3). Mother liquor was removed from the reactor at 28012 g/h via a dip-tube with a filter element and suspension (solid content 300 g/l) was removed at the rate of 12518 g/h on average (controlled by liquid level); the mechanical power input was 2.75 W/l. After 100 hours the reactor reached its steady state and from then on the suspension was collected over a period of 24 hours and then filtered. The filter cake was washed with water and dried for 24 hours at 85 degrees C to give 68.7 (19.3) g product (I) with nickel and cobalt contents of 50.3 (50.8) % and 12.9 (12.7) % respectively, a particle size distribution of D10 = 0.7 (5.8) microns, D50 = 2.6 (14.8) microns, D90 = 5.4 (26.2) microns and D90/D50 = 2.08 (1.77), a tap density (TD) of 2.17 (2.28) g/cm3, a TD/D50 ratio of 0.83 (0.15) g/cm3/micron and a BET surface of 12.8 (14.9) m2/g. Values in brackets were obtained by using mother liquor containing 4.8 g/l NaOH and 11 g/l NH3, using a power input of 0.93 W/l, adding metal salt solution (same composition) at 6328 g/h, NaOH solution at 4367 g/h and ammonia solution at 412 g/h, removing no mother liquor (0 g/h) and removing suspension (solid content 85 g/l) at 11107 g/h.