Sciencemadness Discussion Board

How to make lime or magnesia bricks for an electric arc furnace ?

metalresearcher - 27-11-2025 at 12:20

In the past I have experimented with an EAF using a DC welder and carbon rods. I can melt steel in limited quantities (max 100g) in a few minutes, but the biggest issue is a suitable crucible. Now I have a lanthanated tungsten rod (for a TIG torch) which I attach to the cathode and a steel anode embedded in refratcory mortat.

However, I have read some chapters of Henry Moissan's book on his EAF (much larger than a DC welder) and he used CaO bricks. Should be interesting as these withstand the intense heat of 2000+ºC much better than refractory mortar rated for 1600ºC.

But how can I make these bricks myself ? AFAIK, they are not commercially available. I can only buy lime powder at the local hardware shop. Did anyone make CaO or MgO bricks ?

Admagistr - 28-11-2025 at 13:08

Hi metalresearcher;)! You can buy high-density magnesite bricks, which are heavy, pressed under high pressure, made from MgCO3, and then fired to MgO. I have two pieces so far, but I need to buy more. They are sold in our store, which specializes in fireplace construction.