Yoshiaki Numata

Adsorption of 2-mercaptobenzothiazole onto pyrite

The adsorption of a heterocyclic thioamide (such as 2-mercaptobenzothiazole (MBT) collector) on pyrite has been studied. 2-mercaptobenzoxazole (MBO) and 2-mercaptobenzimidazole (MBM) were used in the tests as references. The flotation of pyrite with MBT, MBO, and MBM has also been investigated. Quantum chemical calculations carried out by the extended Huckel method for adsorption models, MBT ion-pyrite and MBT dimer-pyrite, are used to illustrate the electronic, binding and energy states of the two adsorption systems. It is demonstrated that MBT ions can be chemically adsorbed onto the pyrite surface by the formation of bonds between sulphur and nitrogen atoms of MBT and iron atoms on the pyrite surface. The adsorption of MBT dimer is more stable than that of MBT ion on pyrite. The adsorption of MBT on pyrite is further discussed in terms of the adsorption model of MBT ions onto the pyrite surface with hydrogen and hydroxyl ions previously adsorbed.

Studies on Carrier Magnetic Separation of Fine Wolframite.

Carrier magnetic separation of fine wolframite (-5μm) was investigated using coarse magnetite (37-53μm, etc.) as carriers and sodium oleate as a surfactant by high gradient magnetic separator. Effects of some factors on the carrier magnetic separation were studied. It was found that the recovery of fine wolframite was significantly increased from about 23% by conventional magnetic separation to 94% by carrier magnetic separation at magnetic flux density 0.14T. The recovery of fine wolframite was improved from 50% to 93% by carrier magnetic separation at 0.27T for a mixture of wolframite (-5μm) and quartz (-10μm) containing 10.9% WO3.The improved results of magnetic separation were mainly explained by the size enlargement of the fine wolframite due to the addition of carriers and stirring at high speed. The collision energy between the coarse and fine particles is much greater than that between fine particles. Therefore, aggregation be tween coarse and fine particles occurs more easily. The stability of aggregate of particles is also strengthened due to the hydrophobic forces between particles with the addition of sodium oleate.

Studies on the Adsorption of Heterocyclic Compound with Thioamide onto Copper Mineral

The extended Huckel method was applied to the adsorption of the 2-mercaptobenzothiazole (MBT) ion and the MBT dimmer on chalcopyrite in order to clarify the electronic, binding, and energy states of these adsorption systems. The MBT adsorption on chalcopyrite is rather chemical than physical. An MBT ion can adsorb on chalcopyrite by exchange of an adsorbed hydroxyl ion. An MBT ion can adsorb more preferentially on copper atoms than iron atoms on a chalcopyrite surface. The stabilization energy of the adsorption of the MBT dimmer on chalcopyrite is greater than that of the MBT ion on chalcopyrite.

Some Frothing Characteristics of Frothers

Employing Yarmor F Pine Oil, Nikko Oil No. 125, Du Pont Oil No. 22, MIBC, Dowf roth No. 250 and Takasa Froth No. 5 as examples, frothing characteristics of f rother solutions were studied.Froth height and bubble diameters in aerated solution and in froth layer were estimated at varying concentrations, temperatures and pH values of f rother solutions.It was found that there are close correlations among f rother volatility, froth height and bubble diameters of f rother solutions, all these being naturally related to the molecular constitution and constituents of f rothers.Some consideration was given to the adsorption velocities to account for these correlations.The writers consider that froth texture and viscosity of solution contained in the froth, -these two being themselves interrelated-, are important among factors affecting results of ore flotation.