The Lead Pot

For ballast we require 2.5 Metric Tons of lead to be poured directly into the keel of Rugludallur. There are many things to keep in mind when designing and building a pot to melt any metal, those which have a low melting point like lead 328 °C (600 °K, 622 °F) are much easier than say aluminium 660 °C (933 °K, 1220 °F) or even zinc at 420 °C (693 °K, 787 °F).

We had an old beerkeg collecting dust which we modified, in retrospect it might look like a bit of a waste since it is made of 316 grade stainless steel but we didn't see any other use for it. From the beginning we wanted to be able to close the pot to limit heat loss from radiation and convection (hot air escaping), the trick is to have a reflecting surface which can easily be removed.

For ease of pouring without scalding ourselves we welded a pipe to the side of the pot and gimbalded the pot, it's vital to keep the center of gravity low enough, otherwise you can get into big problems when the lead starts melting*.

The pipe used should have an inside diameter of around 12mm (1/2 inch), this proved to be sufficent for pouring without clogging up.

You probably have several sources of heat readily available to you because of the low temperature requried: Electric Stove, Propane/Butane Burner, Charcoal smelt, Acetyline Burner and Kerosene. The selection depends on efficiency, availability and price.

Here are some examples

Energy content

	kerosene 134.000 BTU/gallon
	butan 101.000 BTU/gallon
	propane 92.000 BTU/gallon
	gasoline 111.000 BTU/gallon
	electricity 3.413 BTU/kWhr (kiloWatt hour)

If you keep in mind that a liter(gallon) of kerosene is much cheaper than propane/butane it is quite clear that it is the cheapest form of fossil fuel.**

Comparing electricity to kerosine we come to the conclusion that we need 40kWh of electricity to produce the same heat we get from 5 liters (1 gallon) of kerosene. Even with very steep fuel prices and very low electric cost in Iceland the kerosene still wins by a factor of 2.

In our case it was also easier, we managed to secure a nozzle from an old "Master Blower" which are kerosene heaters. The nozzle is able to atomize the kerosene so that it burns without any problems, to power the nozzle we used compressed air***

We also equipped the gimbald-stand with a platform for the mold, this enabled us to pour the lead into the mold without concerns for splatter. Holding an extended 20kg mold with liquid lead is neither easy or safe, therefore this should be a priority.

* While the lead is solid it stabilizes the the pot, but when it melts the fluid has a very different effect on the Center of Gravity which could cause the pot to tip over!

** Kerosene is the cleanest, most efficent form of fossil fuel available (better than petrol/gasoline). Kerosene is also known as JET A or simply JET FUEL. Diesel is a form of kerosene with lubricants.

*** This particular nozzle has a system simlar where a stream of rushing air is used to create a vacuum which sucks the kerosene from the tank and blows it out of the nozzle.