抄録
Various experiments for the reduction of thoria by calcium have been performed to determine the most industrially favorable condition for preparing thorium metal. The results obtained are as follows:
(1) Stainless steel having no surface lining is the most suitable material for a reactor vessel, while the yield deteriorates in the case of a graphite reactor vessel.
(2) The optimum particle size of thoria is about 150 μ.
(3) A high yield of metal can be obtained by using CaCl2 flux of 20∼40 per cent for thoria’s weight and about 25 per cent in excess of the theoretical amount of calcium.
(4) The effeciency of reduction becomes the highest by heating for 4 hr at 950°C or for 3 hr at 1050°C.
Under the above-mentioned conditions, about 90 per cent yield of thorium metal and 3∼7 per cent of residue undissolved with HCl can be obtained.
