Donchenko M.I.

Copper Production from a Carbonate Ores by Electrowinning Method

A process of compact copper electrowinning from the solution obtained by leaching copper from the ore by sulfuric acid was discussed. It was shown that the ore leaching is advisable to carry out with 10 % hydrochloric acid for 30–40 minutes with intensive stirring of the mixture. Copper electrowinning process was done from a concentrated solution with a stepped reduction of the current density which was proportional to the copper ion concentration decreasing during the process. The comparison of the parameters of the real and theoretical calculated processes was performed.

Multistage Galvanostatic Method of Electrowinning Copper from Sulphate Solution of Copper Ore Leaching

This paper investigates the process of copper electrowinning from carbonate ore. Copper was leached by sulfuric acid solution. The obtained electrolyte was used for copper electrowinning. We show that step current lowering was the best method to obtain massive cathode deposit or copper foil with 100 % of current efficiency. We make theoretical calculations of the electrolysis process.

Electrodeposition of nickel and composite nikel diamond coatings by reversible current

This study deals with the deposition of nickel diamond composite coatings on steel for producing abrasive and cutting tools. Based on the various sources, including previous research data, we choose the method of electrodeposition of coatings by a reversal current. We deduce the equations for calculating the current density in cathodic and anodic pulses. On the experimental side, we study the influence of these parameters on peak potentials and polarization characteristics of the process, as well as physical and mechanical properties of nickel binder and nickel diamond coatings.

Oxide conversion coatings and its protective properties in mild steel corrosion

We demonstrate the possibility of chemical passivation of mild steel under the influence of oxoanions of the V–VIIth elements of the periodic system in order to form modified films, classified as conversion coatings and stable at atmospheric corrosion. We also suggest a series of solutions for conversion coatings deposition and estimate their stability and corrosion resistance. Employing the electrocapillary curves method, we determine the bromates and molibdates’ adsorption ability.

The influence of the oxyanions on anodic and chemical steel passivation in poorly mineralized water

We study the influence of the oxyanions (CrO42-, WO42-, MoO42-, VO3-, MnO4-, BrO3-, IO3-) on the anodic behaviour of mild steel in poorly mineralized water. Through experiments performed, we demonstrate that bromates and iodates are the most effective passivators; the molybdates guarantee a high stability of the anodic passive films.

The influence of a pulse current on nickel electrodeposition from sulfamate electrolytes

The paper under consideration describes the influence of pulse current parameters on morphology of coatings and electrochemical characteristics of nickel electrodeposition from sulfamate electrolytes. We determine the electrolyze regimes, promoting brightening and reduction of coverings porosity and increase of yield, following the metal current. We demonstrate that the yield, following the current, grows at the increase of on-off time ratio and frequency of a pulse current.