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VIDEO: Gold cyanidation research at Queen's





Video Transcript:

Hello, I am Rina Kim in the hydrometalurgy

group under the supervision of Professor

Ahmad Ghahreman.

I am studying the effect of oxygen on

gold cyanidation especially in the presence

of sulfidic ores.

In my study, oxygen can give positive effects

in two aspects. The first one is oxidation

of sulfide minerals in the ore.

Generally, sulfur and some metal components in

the sulfide minerals can give negative effects

on gold cyanidation, such as the side reaction

concerning leeching chemicals like cyanide

the formation of passive film on gold

surface and so on.

However, once the sulfide minerals are oxidized

then the negative effects can be reduced and finally

the gold oxidation can be improved.

Secondly, gold leeching in cyanide solution is

an oxidative reaction.

So, if we increase the oxygen concentration, the

gold cyanidation can be improved, too.

Additionally, the oxygen can substitute

one of the oxidants, the lead, which is currently

being used in gold processes.

Finally, the environmental problems caused

by the use of lead an be reduced.

To do my study, I'm mainly using the electro-chemical

methods such as cyclic voltammetry, chronoamperometry,

and Electrochemical quartz crystal microbalance (EQCM).

In this fume hood I am running the electro-chemical test

with cyanide solution and some sulfidic ore slurry

and with gold electrodes, another reference electrode and

a counter-electrode.

In here this gold electrode is leeched by the cyanide

solution and the slurry contains some sulfidic minerals

and some sulfidic ores so it gives a positive effect or

negative effect. At the same time I want to see the

effect of oxygen, so I'm injecting oxygen through this

tube and we can see some bubbles of oxygen gas.

All of these electrodes are connected to this

potentiostat which measures the potential and current

so we can get potential-current curves and another

one is by the chronoamperometry we can get the

current-time curves. These are the curves acquired by the

running test. This curve shows current change over time.

So, it shows that this current is decreased by the time because

of some of the effects of sulfide minerals in the ore slurry.

In here, we can see another plot. this is current and

potential curve. In this plot there are some current

peaks. These peaks shows which potential cuases

gold oxidation and how much gold oxidation has occurred.

With the height of this current, we can measure the

amount of gold oxidation.