A substantial amount of silver scrap prepared for melt.
Loading the silver into the 1,000 oz t (68.5 lb) capacity silver furnace.
The silver starts to melt first at the bottom with material
on top slowly descending and becoming part of the liquid pool of metal.
Here most of the solid material has melted into liquid with the remaining solid descending far down into the crucible.
The completely melted silver is stirred to assure
homogeneity.
A pin sample being taken by inserting an evacuated glass tube into the molten metal. The hot metal melts off the end of the inserted tube and the vacuum sucks the metal up into the tube. The substantially lower temperature above the liquid metal causes the sucked up metal to solidify immediately.
The now-solid sample being removed from the melt.
The glass surrounding the pin sample is knocked off with a
hammer on the melt table.
The cleaned sample on the melt table. Taking a sample from the metal while it is
molten is generally agreed to be one of the best ways to assure a uniform
and representative sample.
The metal being pouring into a large graphite form.
The final scraping out of the crucible to insure that
nothing is left behind.
The bar cooling in the form.
The black, almost tar-looking top, is not the bar but the melted borax
(flux that was added to the melt) and other things such as stones and other
impurities. This material floats to the
top and forms a layer or crust on top of the bar which will later fall off and
be removed in the cooling and cleaning process.
The unmolded bar and form on the melt table. The bar has
been flipped over in the process of unmolding.
If you look carefully you can see the “slag” layer between the bar and
the surface of the melt table.
The bar being cooled under water.
Here you can see the slag that has been removed from the bar, to the right in the bottom of the pan.
The final weighing of the bar. You can see in front of the bar pieces of the
pin sample that will now be sent for assay (the analysis to determine the amount
of silver contained). When a melt is
done in this manner, the bar is completely homogeneous. Thus the per cent of silver present in the
sample will be identical to the per cent that is in the bar. In this way, once the assay is completed, the
exact amount of pure silver present will be known.