All the neutralising materials were graded to 2 mm.
Properties of selected neutralising materials Neutralising materials Particle size (mm) Limestone [is less than or equal to] 2.0 Dolomite [is less than or equal to] 2.0 Fluidised bed boiler ash [is less than or equal to] 2.0 Reactive phosphate rock [is less than or equal to] 2.0 Neutralising materials Equivalent Acid-neutralising Ca[CO.sub.3] capacity (%) (kg Ca[CO.sub.3]/t) Limestone 95 1010 Dolomite 114 1135 Fluidised bed boiler ash 42 438 Reactive phosphate rock 27 689(A)
Neutralising material requirements: an incubation study
Air-dried pitwall rock bulk samples of 200 g were weighed into the plastic bags and mixed with varying Ca[CO.sub.3] equivalent rates ([C.sub.ER]) of the 4 neutralising materials used, and incubated at 20 [degrees] C for 90 days.
Neutralising material requirements of the pitwall rock
After the 90-day incubation, the rise in pH of the pitwall rock with increasing [C.sub.ER] of neutralising materials followed a sigmoidal type log function of the form:
The requirements of neutralising materials to raise the pH of pitwall rock incubated for 90 days to [is greater than] 6.0 predicted from the function are presented in Table 4.
Neutralising material required to raise pH above 6.0 in pitwall rock
[LR.sub.Buffer], buffer rate lime requirement; [LR.sub.Total], total lime requirement; LST, limestone; DOL, dolomite; FBA, fluidised bed boiler ash; RPR, reactive phosphate rock Neutralising [LR.sub.Buffer] Ca[CO.sub.3] materials (kg Ca[CO.sub.3]/t) equivalent (%) Ca[CO.sub.3] 29 100 LST 32 95 DOL 25 114 FBA 30 42 RPR(A) 88 27 Neutralising Actual rate [LR.sub.Total] materials (kg/t) (kg/t) Ca[CO.sub.3] 29 111 LST 34 120 DOL 22 94 FBA 71 266 RPR(A0 326 630
Elicitation of neutralising antibody is a much sought goal for an HIV/AIDS vaccine, said Dr Harriet Robinson, GeoVax's chief scientific officer, adding that the field has been trying to achieve this goal by re-engineering the HIV envelope protein that mediates entry into cells.
GeoVax is extremely pleased that its natural form of the HIV envelope protein can elicit neutralising Ab for tier 2 viruses Dr Robinson continued.