Takahide Wakamatsu

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.

Separation of Nickel, Cobalt or Iron in a Synthetic Leach Solution of Manganese Nodule with Two Components

Separation and recovery of nickel, cobalt, or iron in a synthetic solution with two components similar to a solution from manganese nodules leached by sulphuric acid were investigatdd as a function of the concentration of collectos as diethyl-and dimethyl-carbamates or of pH. Nickel and iron in each quasileach solution were collected over 900, but cobalt was collected in a little lower percent . Iron and nickel or iron and cobalt in the two constituent solution have to some extent a possibility to separate each other using the above mentioned collectors around pH=1. Separation of iron and nickel is better than that of iron and cobalt on the basis of the separation index. Separation of iron and cobalt is improved around pH=2.5. Flotation products from quasi-leach solution may be identified as metalcollector complexes by IR spectra. The conditional stability constant of metals with collector explains a tendency in the flotation recovery of these complexes as a function of pH .

Consideration for Some Problems and Improved Measures of Separation of Cu-Zn Ores

It is well known that the separation of copper and zinc minerals in the complex sulphide ores flotation is very difficult. On the other hand, it is also important to recover sphalerite entrained in the copper concentrate which is produced from the concentrators treating Cu-Pyrite ores and to recover chalcopyrite entrained in the zinc concentrate which is produced from the concentrators treating the Pb-Zn ores. Thus, the separation technique of Cu-Zn ores includes many difficult problems which have to improve.In this paper, the authors considered on many problems for the separation of Cu-Zn ores and discussed on how to separate the above minerals from the research works of the previous papers of the authors and others. There are many reasons why the separation of Cu-Zn ores is very difficult. One of them is the copper ions existing in the flotation pulp. Accordingly, the prevention and deactivation of the copper-activated sphalerite were discussed in order to separate the Cu-Zn ores.Among the previous research works which were carried out by the authors, the prevention and deactivation of copper activation for sphalerite were most effective by the use of sodium sulphide and ferric ion solution containing sulphuric acid. The effect of sodium sulphide on the prevention of copper activation for sphalerite was studied in the presence of sulphurous acid or sodium cyanide used as a depressant of sphalerite. From the results obtained, it may be considered that the copper activation of sphalerite is prevented perfectly by the use of sodium sulphide. Then the deactivation of the copper-activated sphalerite was investigated in a series of the laboratory experiments by the use of ferric ion solution containing sulphuric acid. From the results obtained, it was recognized that the deactivation of copper-activated sphalerite could be attained remarkably by the treatment of 980 mg/l Fe+++ solution containing over 4 vol. % of H2SO4. O2 gas accelerates the deactivation of the copper-activated sphalerite by the treatment of the above both solution. The temperature is one of the important factors for the deactivation. Using the flotation machine, the differential flotation test of Cu-Zn ore were carried out. The separation of Cu-Zn ore was successful by the deactivation treatment for Cu-Zn ore.From the recent paper by R. M. Manser and P. R. A. Andrews, a new reagent, Kr6D, as a depressant for sphalerite in a differential sulphide flotation stage was introduced in this paper. Small-scale laboratory flotation tests on such pure sulphide minerals as sphalerite and chacopyrite indicated that the Kr6D is capable of depressing sphalerite when used in small doses. At higher concentrations, chalcopyrite is also depressed. Single-stage batch-scale flotation tests were carried out on bulk concentrates containing the sulphide minerals. The Kr6D was compared with starch as a depressant both in the presence and in the absence of sulphur dioxide. In each case the new modifier was shown to be more effective.In addition to the above methods for the separation of Cu-Zn ores, the authors considered the possibility of improving selective flotation of bulk flotation concentrates from the previous papers of some other authors, including the abrasive action of high temperature and electric current for the adsorption collector layer on sphalerite and chalcopyrite. The desorption of collector layer on the Cu-Zn bulk concentrate by the use of sodium sulphide was discussed.