This paper presents results of a study on minimising the specific power for off-bottom solids suspension in mixing tanks at a high solids concentration It was found that major savings in the specific power required to suspend solids at high concentrations can be achieved by removal of baffles This is particularly relevant to applications where chemical reaction rate is not affected by the mixing rate, such as that often occurs in the mineral industry The specific power at the lust off-bottom solids suspension condition was found to decrease with the tank diameter at a rate a lot faster than previously reported in the literature It appears that a larger power number axial flow impeller is more energy efficient than a lower power one to suspend solids at a very high solids loading A mineral processing full-scale tank is used as a benchmark in the study Emphasis was placed on applications to the mineral industry, although results are also relevant to other industrial applications