Preliminary Results on Chemical Separation of Ruthenium from Molybdenum Mineral by Distillation and Isotope Analysis of Ruthenium by Surface Ionization

Abstract

Preliminary results are reported on the separation of small amount of ruthenium from large amount of molybdenum sulfide and on the neutron-activation analysis of ruthenium in a molybdenite.
The chemical yield for ruthenium in the distillation was checked by using a radioactive tracer ¹⁰⁶Ru (T_1/2=1yr.)and by counting 512KeV and 622KeVγ-rays from¹⁰⁶Rh(T_1/2=30sec)which is in radiation equilibrium with ¹⁰⁶Ru.
The procedures for fusion and distillation are as follows. Molybdenum sulfide of about0.1g was fused with sodium peroxide flux(ca.1.5g)in a nickel crusible, and then the black slurry extracted with 20ml of water was dissolved by 40ml of sulphuric acid(1:2)in a distillation flask. The known amount of tracer ¹⁰⁶Ru was added to the solution. Osmium was removed by the distillation with hydrogen peroxide(30%). The ruthenium was distilled using 20ml of sodium bromate(20%)and 5ml of concentrated sulphuric acid added in the flask and with the air current through the distillation apparatus. The distillate was absorbed in two receivers, each containing 5ml of 9N sodium hydoxide or 10ml of 5%ethanol-0.2N hydrogen chrolic acid mixture.
Comparing the counts of recovered ¹⁰⁶Ru with the counts of added one, the distillation yield of 96.5%ruthenium was obtained in a single distillation, and in the doubly repeated 99.5%.
In order to determine an amount of ruthenium in the molybdenite quantitatively, 85mg of the molybdenite was bombarded by pile-neutrons, together with a standard sample including 7.9μg of ruthenium.
The ruthenium was separated from each neutron-irradiated sample by the same distillation procedures as described above. As a carrier, 216μg of ruthenium was added at the stage of fusion of the neutron-irradiated molybdenite. The distillate for the molybdenite was compared with the one for the standard sample by counting 498KeV γ-rays from radioactive ¹⁰³Ru(T_1/2=40d.)resulted from the neutroncapture on ¹⁰²Ru. The countings were undertaken using a NaI(Tl)scintillation counter with an anticoincidence guard, along with a 512-channel pulse-height analyser. The concentration of ruthenium in the molybdenite was estimated to be 37×10^-9g/g.
An isotopic abundance of reagent ruthenium was tentatively measured by a single focusing mass spectrometer with a surface ionization source of a tungsten single filament. About5μg of ruthenium as chrolide was heated to dryness on a tungsten filament in air, and then was pre-heated to dull red in vacuum for two days. The isotopic abundance obtained is reported.