Day 29: Extracting
Well, I feel pretty
bad this morning, but the show must go on ... what with it being show
business and all that! I find it very difficult to move freely but everyone's
so sympathetic and understanding. I feel a right passenger. Thank goodness
that making the gold-mercury amalgam won't be that time-consuming, or
turns out that Mikey managed to crush most of the rock while I was away
yesterday, so we should be ready to rock (no pun intended) and roll by
10am. All we have to do today is react the gold with the mercury to form
an amalgam and then recover the gold (in a purified form). To do this,
you grind the crushed ore with the mercury in a pestle. In doing so, you
can see the physical nature of the mercury change as it reacts with the
gold in the rock. The amalgam is a grey semi-solid that looks neither
like gold nor mercury. The amalgamation process is similar to dissolving
the gold in the mercury, only it's not quite that simple. Most metals
will form an amalgam with mercury and it's a process that's been used
for years to purify metals like gold.
weird thing about amalgams is that it's easy to recover the original metals.
All you have to do is heat the amalgam up and, hey presto, you recover
both the gold and the mercury. The problem is that mercury's really toxic
and we have to be careful that, by heating the amalgam, we don't force
the mercury to evaporate into the atmosphere. Mikey L comes up with a
really neat Rough Science way of doing it safely - using a potato. All
you do is place the amalgam under a potato that's been cut in two lengthways,
with a small indentation cut into one of the raw sides. Placing the indentation
over the amalgam and heating the potato up, drives off the mercury and
re-generates the gold. The beauty of the process is that as the mercury
evaporates, it's taken up into the flesh of the potato, and never has
a chance to escape into the atmosphere.
Neat eh!? By the end
of the day, we've extracted and purified all of our gold using the amalgamation
process. We end up with quite a sizeable nugget as things turn out.