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On the basis of results obtained from small-scale laboratory work, equipment for the production of 60 pounds of zirconium sponge a cycle has been placed in operation.Zirconium carbide, prepared from zircon and earl)on in an electric arc furnace, is chlorinated in improved equipment capable of producing over 300 pounds a day. The raw zirconium chloride is purified in a unit which accommodates nearly 200 pounds. Reduction by magnesium is carried out in the same furnace as the purification. Excess magnesium and magnesium chloride are removed by a combination melting and vacuum distillation method. The zirconium sponge is pressed into briquets and melted in graphite crucibles in a new graphite resistor vacuum furnace capable of melting over 10 pounds of zirconium a charge.

An improved resistor furnace is reported on, which operates more satisfactorily for certain purposes than an induction furnace. The new furnace employs a slotted tube so that the current must go up one half and down the other. Both electric connections are at the bottom of the slotted tube. The electric resistance is almost four times that of a similar unslotted tube with top and bottom clamps. The new furnace operates at an estimated 38% efficiency.

It is shown that gaseous zirconium chloride can be piped to a reactor containing magnesium and that the reaction salts can be repeatedly tapped to make room for more magnesium, in view of continuing the reduction. This permits using the crucible capacity more fully, with consequent reduction of the production cost.Experiments indicate that part of the magnesium used for the reduction of zirconium chloride can be replaced with sodium. The advantages and disadvantages of this proposition are discussed.Cast iron is a better crucible material than mild steel when used in contact with hot zirconium. A layer of zirconium carbide is formed by zirconium diffusion, which helps reduce iron contamination.