Electro-hydrometallurgy of ciulcoyyrites – vii an appraisal of ferric chloride leaching process

Importance of hydrometallurgical route for processing chalcopyrite recovery of copper is highlighted. Conditions for ferric chloride leaching process have been standardized involving the recovery of copper by galvanic cementation as well as electrolysis in diaphragm cell

Modelling and simulation Of electrochemical processes

Conventional reaction engineering technique may be applied to electrolytic process with emphasis on residence time distribution (RTD) metho

Stress corrosion cracking of prestressing steel in sulphide medium

Stress corrosion cracking behaviour of colddrawn and stress-relieved prestressing steel of standard quality conforming to IS. 1785- Part I has been studied in H2S saturated aqueous solution with and w~thout chloride. The steel was found to be highly susceptible to cracking even under open circuit condition at room temperature.The suscept~b~litdye creased slightly with temperature in the range 3O0C- 80°C. The threshold stress was found to increase with pH of the medium from 15%of proof stress at pH 2.6 to 40 %of proof stress at pH 6.5. A limiting pH of 7 above which stress corrosion cracking did not occur was obtained for water- H2S system and the corresponding value in 3.5PbNaCI- H2S system was found to be 9. Cathodic polar~sationd ecreased the time to failure while anodic polarisation increased the time to failure. Application of tensile stress was,found to increase the corrosion rate and also the solubility of hydrogen. The strain rate was found to have profound influence on the cracking process and the susceptihlity was h~gha t very low stram rates. SEM fractographic studies revealed that the fracture mode was predominantly intergranular. All these observations could be understood in terms of a decohesion mode

Calculation and experimental verification of m drop in tsia electrodes of chlor-alkali cells

A computer program to analyss the current distribution in a chlor-alkali cell using Titanium Substrate Insoluble Anode (TSIA) has baen developed. The program takes into account the polarisation resistance characteristics of anode and camode and the electrolyte resistance, in a d d i i to anode nodal resistance. The results are compared with the experimental data

Electroplating OF Silver-Cadmium alloys

Silver cadmium alloys are repurted to have increased hardness, electrical conductivity and tarnish resistance. Electroplated coatin~s of these alloys find applicatinns a.s bearing alloy, non-tarnishing coating and electronic coating material. The standal-d electrode potentials nf silver and cadmium are tno far apart to penllit co-deposition from simple salt solutions. Suitable complexing is necessary to bring the deposition potential c1oser and permit codeposition, Various types of solutions have heen investigated by the authors to explore the possihility of electroplating alloys with varying proportions of silver and cadmium and the results are presented in this paper. Electroplating experiments were carried out under varying concentrations of metal and operating condition, Cyclic and stripping voltammetric techniques were employed. Charaderisatioill of deposits were done hy X-ray diffraction. scannin~electron microscopy and microhardness measurements

Modelling and simulation of electrochemical processes

Conventional reaction engineering technique may be applied to electrolytic process with emphasis on residence time distribution (RTD) metho

Packed bed reactor for oxidation of glucose

In order to improve the performance of three dimensional electrodes for synthesis of electroorganic compound, investigations have been carried out in a packed bed reactor of flow-by configuration with batch recirculation system. This paper also deals with some aspects of modelling for such an investigation

Porous iron electrode for alkaline batteries

A method for characterising the sintered iron electrode based on triangular potential sweep voltammetry has been developed. The peak potential separation and (Qc/Qa) at zero sweep rates have bean used as criteria of reversibili. The best composition based on using various iron powders, a - Fe304 and various additives has been recommended. Gasometric method to determine the self-discharge current and discharge studies of nickel-iron cell have been presente