6
CONCLUDING REMARKS
Laboratory studies using the MagoMill ® where careful
attention is paid to matching the plant pulp chemistry in
the laboratory does provide a reasonable guide of what to
expect converting from forged steel to an appropriate high
chrome alloy in terms of changes in the pulp chemistry,
changes in reagent consumption and improvements in con-
centrate grade and recovery.
In this paper, work completed on porphyry copper
deposits is highlighted. Laboratory tests and plant tri-
als have been completed on several copper-gold porphyry
ores in the western and northern parts of the Pacific rim.
Broadly, converting these ores from forged steel to a high
chrome alloy resulted in the pulp chemistry shifting to
more oxidizing Eh values, higher dissolved oxygen con-
centrations, lower oxygen demand and lower amounts of
EDTA extractable iron (reduced corrosion). The shift to
more oxidizing conditions translated to higher copper and
gold recoveries in the laboratory. It is also noted that using
high chrome grinding media lead to a reduction in lime
consumption either to achieve the same pH or operate at a
lower pH. The laboratory work did lead to plant trials, and
similar changes in the pulp chemistry were observed. It was
also noted that the copper recoveries obtained in the plant
trials were nominally 50 percent less than those reported
in the laboratory work, with the gold recoveries about the
same in both the laboratory and the plant. Lime consump-
tion was also decreased.
The eastern Pacific rim is populated by a large number
of copper-molybdenum porphyry copper deposits, and the
laboratory work has shown encouraging results. Broadly,
there do not appear to be significant changes in the Eh or
dissolved oxygen content of the pulp when moving from
forged steel to high chrome, and this can be attributed to
the high pH regime employed in these ores. However, the
oxygen demand and EDTA extractable iron are reduced
significantly indicating that the media corrosion has been
inhibited with the change to a more electrochemically inert
media. Both the copper and molybdenum recoveries for
the two examples cited have improved by changing to high
chrome grinding media. Further, it looks like it should be
possible to reduce the lime consumption once the new pulp
chemistry is in place.
Extrapolating the laboratory results for the copper-
molybdenum porphyry ores to the plant assumes that
nominally 50 percent of the copper recovery improvement
noted in the laboratory will be achieved in the plant. And, it
is highly likely that the molybdenum recovery will increase
as well because the lime consumption should be lower,
which means that there will be less calcium ions in the pulp
to contaminate the surfaces of the molybdenite, improving
its natural hydrophobicity. Therefore, it would be expected
that converting a plant treating a copper-molybdenum
Figure 3. Copper grade/recovery curves for copper rougher flotation tests on a North
American copper-molybdenum porphyry ore
CONCLUDING REMARKS
Laboratory studies using the MagoMill ® where careful
attention is paid to matching the plant pulp chemistry in
the laboratory does provide a reasonable guide of what to
expect converting from forged steel to an appropriate high
chrome alloy in terms of changes in the pulp chemistry,
changes in reagent consumption and improvements in con-
centrate grade and recovery.
In this paper, work completed on porphyry copper
deposits is highlighted. Laboratory tests and plant tri-
als have been completed on several copper-gold porphyry
ores in the western and northern parts of the Pacific rim.
Broadly, converting these ores from forged steel to a high
chrome alloy resulted in the pulp chemistry shifting to
more oxidizing Eh values, higher dissolved oxygen con-
centrations, lower oxygen demand and lower amounts of
EDTA extractable iron (reduced corrosion). The shift to
more oxidizing conditions translated to higher copper and
gold recoveries in the laboratory. It is also noted that using
high chrome grinding media lead to a reduction in lime
consumption either to achieve the same pH or operate at a
lower pH. The laboratory work did lead to plant trials, and
similar changes in the pulp chemistry were observed. It was
also noted that the copper recoveries obtained in the plant
trials were nominally 50 percent less than those reported
in the laboratory work, with the gold recoveries about the
same in both the laboratory and the plant. Lime consump-
tion was also decreased.
The eastern Pacific rim is populated by a large number
of copper-molybdenum porphyry copper deposits, and the
laboratory work has shown encouraging results. Broadly,
there do not appear to be significant changes in the Eh or
dissolved oxygen content of the pulp when moving from
forged steel to high chrome, and this can be attributed to
the high pH regime employed in these ores. However, the
oxygen demand and EDTA extractable iron are reduced
significantly indicating that the media corrosion has been
inhibited with the change to a more electrochemically inert
media. Both the copper and molybdenum recoveries for
the two examples cited have improved by changing to high
chrome grinding media. Further, it looks like it should be
possible to reduce the lime consumption once the new pulp
chemistry is in place.
Extrapolating the laboratory results for the copper-
molybdenum porphyry ores to the plant assumes that
nominally 50 percent of the copper recovery improvement
noted in the laboratory will be achieved in the plant. And, it
is highly likely that the molybdenum recovery will increase
as well because the lime consumption should be lower,
which means that there will be less calcium ions in the pulp
to contaminate the surfaces of the molybdenite, improving
its natural hydrophobicity. Therefore, it would be expected
that converting a plant treating a copper-molybdenum
Figure 3. Copper grade/recovery curves for copper rougher flotation tests on a North
American copper-molybdenum porphyry ore