Using nitrogen gas to remove oxygen in Copper Sulphide flotation
By using nitrogen gas to exclude oxygen and by careful control of sulphidisation process it has been possible to increase the flotation recovery of chalcocite, chalcopyrite, bornite, and covellite that would otherwise have reported to tailings. The process implanted by BOC gases is called Maxifloat TM [23].
It is recognized that a significant proportion of metal losses in the flotation tailings is presented as liberated minerals of a size range, which should be readily floatable. In a copper mine these minerals would include primary and secondary copper sulphides. The value of these metal losses would readily justify the application of a process capable of improving their recovery. Metallurgists generally accept that the value sulphide minerals reporting to the flotation tailings are oxidized to some extent. The nature of this oxidation is evident as tarnished surfaces or surface oxide coating of the underlying primary sulphide minerals.
The process of sulphide mineral oxidation occurs during the following stages of processing: in situ ore weathering, mining operations, stockpiling, crushing, milling, and flotation. The oxidation reactions arise from the presence of oxidants as well as galvanic interactions between sulphide minerals, milling media and solution species.
The results from 10 separated bench scale investigations are shown in the next table:
Table 2. Flotation test results (taken from [23]).
Ore Type |
Copper Minerals |
NaHS (gpt) |
Copper recovery (%) | |||
Dominant |
Minor |
Control |
MaxifloatTM |
Increase | ||
Porphyry (South America) |
Chalcocite |
Chalcopyrite Covellite |
23.1 |
81.4 |
90.9 |
9.5 |
Porphyry (Australasia) |
Chalcopyrite |
Chalcocite
|
159 |
78.6 |
80.2 |
1.6 |
Porphyry (Africa) |
Chalcopyrite |
Bornite Chalcocite |
20.3 |
83.6 |
85.3 |
1.7 |
Porphyry (Nth America) |
Chalcopyrite |
Chalcocite Rimmed Pyrite |
2 |
88.6 |
88.2 |
1.6 |
Porphyry (Nth America) |
Chalcopyrite |
Chalcocite
|
10.8 |
86.1 |
88.3 |
2.2 |
Porphyry (Nth America) |
Chalcopyrite |
Chalcocite
|
10.2 |
81.2 |
83.9 |
2.7 |
Porphyry (Nth America) |
Chalcopyrite |
Chalcocite
|
5.6 |
90.2 |
91.2 |
1.0 |
Porphyry (Nth America) |
Chalcopyrite |
Chalcocite Chrysocolla Native Copper |
32.9 |
85.1 |
87.1 |
2.0 |
Porphyry (Australasia) |
Chalcopyrite |
Bornite
|
11 |
87.7 |
93.7 |
6.0 |
Sedimentary (Australasia) |
Chalcocite |
Bornite Chalcopyrite |
122 |
83.9 |
84.5 |
0.6 |
The Gravity Method Types of Xanthates Heavy-Media Separation Terms Used in Crusher Operation Use Quality Crusher Parts Mining Equipment South Africa Tungsten Ore Flotation Flowsheet RECOVERING GOLD BY FROTH FLOTATION The Apatite Group – Apatite Composition, Crystallization & Structure Power Requirements of Crushers Metal Sulfides, Basic and MonoSulfide Division, Galena Group Isometric Phenacite Composition, Crystallization & Structure Anhydrite Composition, Crystallization & Structure HorsePower drawn on new liners Graphic analysis of Mill Liners
