The Solution Interaction of Tetrathionate Ions and Sodium Isobutyl Xanthate and Its Effect on the Flotation of Galena and Chalcopyrite

Tetrathionates have been found in significantly high concentrations in recycled process waters from massive sulphide ore processing plants. These polythionates react with xanthate added to flotation pulps thus reducing xanthate dosages in solution potentially affecting flotation performance. The current study focused on the effect of the tetrathionate-xanthate reaction on sulphide mineral recoveries. Ore dissolution studies confirmed the generation of tetrathionates by copper-lead-zinc ores. In 20 min, the tetrathionates consumed more than half of the xanthate in solution at pH 7. Rest potential measurements and Fourier transform infrared spectroscopy (FTIR) showed that the degree of collector-mineral interactions of xanthate and both galena and chalcopyrite was greatly reduced in the presence of a 2000 mg/L tetrathionate solution. Microflotation tests showed that chalcopyrite recovery was less sensitive to tetrathionates as indicated by small changes in mineral recoveries. Galena was sensitive to the action of tetrathionates on the mineral surface as the galena recovery significantly declined when floated with xanthate as a collector in both a 500 mg/L tetrathionate solution and a 2000 mg/L tetrathionate solution. These fundamental results lay a sound base on which more discussion into the significance and the effect of tetrathionates on flotation performance of sulphide ores can be developed.

Aktifitas Listrik pada Otot Jantung

AbstrakKontraksi sel otot jantung terjadi oleh adanya potensial aksi yang dihantarkan sepanjang membran sel otot jantung. Jantung akan berkontraksi secara ritmik, akibat adanya impuls listrik yang dibangkitkan oleh jantung sendiri. Potensial aksi pada membran saraf dan otot rangka dapat terjadi bila ada rangsangan dari luar sedangkan pada membran sel otot jantung potensial aksi dapat terjadi tanpa adanya rangsangan. Berbeda dari sel saraf dan sel otot rangka yang memiliki potensial membran istirahat. Sel-sel khusus jantung tidak memiliki potensial membran istirahat. Sel-sel ini memperlihatkan aktivitas “pacemaker” (picu jantung) berupa depolarisasi lambat yang diikuti oleh potensial aksi apabila potensial membran tersebut mencapai ambang tetap. Hal ini menimbulkan potensial aksi secara berkala yang akan menyebar keseluruh jantung untuk menyebabkan jantung berdenyut secara teratur tanpa adanya rangsangan melalui saraf. Potensial aksi sel otoritmik jantung mempunyai 4 fase: fase 0 (depolarisasi cepat), fase 1 (repolarisasi awal), fase 2 (plateu), fase 3 (repolarisasi cepat), fase 4 (istirahat).Kata kunci: aktifitas listrik otot jantung, potensial aksi AbstractThe heart muscle cells contraction occur by potential act delivered throughout heart muscle cell. The heart will contract ryhtmically, result from existence of electric impulses excited by heart its self. The potential act at cells membrane of nerve cells and striated muscle can occur when there is stimuli from outer, while cells membrane of heart muscle can occur without stimuli. Nerve cells and striated muscle cells have rest potential membrane, specific heart cells have no rest potential membrane. These cells show “pacemaker activity, are slow depolarization followed with potential act when the potential membrane reach the stable threshold. Therefore, the potential act appear periodically that will spread throughout the heart and cause heart bite regularly without stimuli via nerve. The potential act of heart autorhytmic cell have 4 phase: phase 0 (fast depolarization), phase 1 (initial repolarization), phase 2 (plateau), and phase 4 (resting).Keywords: electric activity, heart muscles, potential act.

High Temperature Corrosion of Inconel 600 in NaCl-KCl Molten Salts

In this work the corrosion resistance of a high content nickel alloy, Inconel 600, was investigated in mixed NaCl-KCl salts at 700, 800, and 900°C for 100 hours in static air. Investigation was carried out using electrochemical techniques such as polarization curves, rest potential measurements, linear polarization resistance, and electrochemical impedance spectroscopy. Corroded specimens were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Electrochemical measurements showed an increased degradation rate of Inconel 600 with increasing test temperature. SEM and EDS analysis show that the damage experienced by Inconel 600 is greater than that determined by electrochemical measurements. This damage was identified as internal corrosion due to the reaction of Cl2with the alloying elements (Cr and Fe); however, at 900°C the internal damage was minor and it was associated with the nickel content in the alloy.

The Influence of Pyrite on Galvanic Assisted Leaching of Chalcocite Concentrates

The dissolution of metal sulfides is controlled by their solubility product and valence bond theory, pyrite and chalcocite have different electronic nature of the valence energy band, with which the electrolyte may exchange electrons during dissolution reaction, so they have different principals of dissolution. Pyrite which has a higher rest potential is galvanically protected, while chalcopyrite which has a lower rest potential is preferentially leached. Pyrite is intentionally added to the leaching of chalcocite concentrates, we investigated the influence of pyrite to chalcocite weight ratio, solution pH , Eh and the presence of bacteria on assisted leaching of chalcocite concentrates. The leaching solution redox potential, pH, iron, copper and bacteria were monitored, leached residue was collected and analysed to understand leaching mechanism. We found that chalcocite leaching efficiency is enhanced with pyrite:chalcocite weight ratio increased.

Galvanic Interaction between Chalcopyrite and Pyrite with Low Alloy and High Carbon Chromium Steel Ball

This study was aimed to investigate the galvanic interaction between pyrite and chalcopyrite with two types of grinding media (low alloy and high carbon chromium steel ball) in grinding of a porphyry copper sulphide ore. Results indicated that injection of different gases into mill altered the oxidation-reduction environment during grinding. High carbon chromium steel ball under nitrogen gas has the lowest galvanic current, and low alloy steel ball under oxygen gas had the highest galvanic current. Also, results showed that the media is anodic relative to pyrite and chalcopyrite, and therefore pyrite or chalcopyrite with a higher rest potential acted as the cathode, whilst the grinding media with a lower rest potential acted as the anode, when they are electrochemically contacted. It was also found that low alloy steel under oxygen produced the highest amount of EDTA extractable iron in the slurry, whilst high carbon chromium steel under nitrogen atmosphere led to the lowest amount.

Effects of Galvanic Interaction on Collectorless Flotation Behavior of Galena and Pyrite

Galvanic interactions between sulfide minerals have significant effects on their electrochemistry and flotation behavior. The effects of galena and pyrite on their collectorless flotation behavior have been studied in this paper. The results showed that galvanic interaction between galena and pyrite would occur when they were mixed. In the galvanic-couple , pyrite forms a cathode due to the higher rest potential, and is reduced, which results in its floatability decreased; while galena forms a anode due to the lower rest potential, and is oxidized, which results in its floatability increased.