Flotation

The collective flotation of the sulphurs was selected, looking towards the recuperation of the noble materials, in this case the gold and the silver associated to the sulphured minerals exist in the mineral.

The practices of flotation were performed in rough granulometry (81,7% - 65 nets), looking for a significant discarding of mass in the rejection, with less time of grinding, onerous stage of benefitting of a mineral.

The practices of flotation were performed in a Denver cel of laboratory, model D-12, using a tonnel with capacity for ten liters.

In the practices 2 kilograms of mineral to one granulometry of 81.7% were used under 65 nets. The agitation of the cel was mantained constant (1,100rpm) for all the tests. The percentage of solids in the flotation was of 17.6%.

The concentrates of each stage were joined, resulting a total time of 18 minutes for the flotation and of 25 minutes for the conditioning.

The variables studied in the practices of flotation were: pH, granulometry and system of reactives. The best conditions and results of the flotation were obtained in the practices of number 23.

Conclusions (First Stage)
The studies of the collective flotation in scales of laboratories of the sulphured mineral of El Dorado, allowed to obtain a concentrate with tenors of 10.7 g/t of gold and 70.0 g/t of silver, with recuperations of 86.8% for gold and 85.2% for silver. The discarding of mass was of the order of 63.5% according to the practice.

- since gold and silver are finally disseminated and distributed in the sulphured minerals, without any prefference, the method of concentration most indicated was that of collective flotation of all the sulphures. Taking into account that the amount of sulphurs in the mineral of El Dorado is very significant, around 29%, it was not possible to obtain a concentrate with tenors of gold and silver more elevated.

- The recuperation of gold could reach values superior to the 86% in the case in which part of the gold were not disseminated in the ecorodite mineral (10%), which is not recuperated in the collective flotation of the sulphurites.

- The reactives tested were selective and the results pointed for the mineral in question as adequate, the following reactives:

• Aeroxantate – 350   75 g/t
• Crescilic acid       80 g/t
• Pine oil            30 g/t
• Aerofloat – 15      15 g/t
• Copper Sulphate     70 g/t
• Sodium Carbonate   165 g/t