Obtaining microdispersed iron-nickel powder in the process of electrochemical processing of VNZh type heavy tungsten alloys

The process of electrochemical processing of the VNZh type heavy tungsten alloy (wt. %: 80 W, 16 Ni, 4 Fe) under the action of direct and alternating current of industrial frequency in an ammonia-alkaline solution has been investigated. It was found, that the process is accompanied by the transition of tungsten from the alloy to the solution and the formation of a microdispersed powder, based on iron and nickel.

Approach to setting the mode parameters in combined electro-erosive - electrochemical processing during piercing the deep holes of small diameter

The article considers the problem of forming the deep holes of small diameter by using the combined electro-erosive and electrochemical machining based on the electrochemical and electro-erosive processes. The approach to setting the mode parameters during piercing the deep holes with a diameter of less than 1 mm is suggested. The approach takes into consideration the influence of hydrodynamic losses in the inter-electrode gap on the limitation of the mode parameters of the electrochemical and electro-erosive components in the combined processing. It also takes into account the interrelation between the magnitude of the inter-electrode gap and the linear velocities of the removal of the processed material in each of the components during the combined processing. The validity of the approach to setting the mode parameters in the combined electro-erosive -electrochemical processing during piercing the deep holes with a diameter from 0.3 mm to 1 mm in the range of the inter-electrode gap from 0.025 mm to 1 mm is experimentally confirmed.

Resource-saving processing of technological solutions and wastewater by electrochemical method (methods overview)

The paper summarizes the data on the wastewater formation from a number of plants of chemical, engineering, energy and leather industries and its processing in electrolyzers of various designs to obtain the substances that can be used in various production processes. In the ethylenediamine production, wastewater occurs at the stages of amines rectification and of ethylenediamine dihydrochloride neutralization. Recycling of effluents generated during the amine rectification in a two-chamber electrolysis cell allows the ethylenediamine and ammonia to be returned to the production process. The processing of ethylenediamine dihydrochloride solution in the membrane electrolyzers saves alkali for the neutralization process. Electrochemical processing of distilled liquid in soda production makes possible to obtain calcium hydroxide, sodium hydroxide and hydrochloric acid or chlorine, which can be used in various industrial processes. Wastewater generated during the demineralized water production contains a significant amounts of sodium sulfates and chlorides. The processing of these effluents in a membrane electrolyzer yields sulfuric acid and alkali, which are suitable for the regeneration of ion-exchange filters. After processing in an electrodialysis apparatus the wastewater generated during the chromium and nickel coatings, is concentrated to values that allow them to be used to prepare an electrolyte adjustment. The leather industry effluents contains an amount of trivalent chromium and sulphides. Electrochemical processing of these effluents leads to almost complete extraction of chromium and sulfides.

Influence of hydrodynamics of electrolyte flow during electrochemical treatment on the quality of the treated surface

The features of the hydrodynamics of the electrolyte in the interelectrode gap during electrochemical processing of a profile axisymmetric workpiece are considered. The distribution of average flow rates and flow lines is calculated for a specified electrolyte supply. The nature and rate of the electrolyte flow are established. The unevenness of the current density is determined taking into account the change in the electrical conductivity of the electrolyte from heating and gas filling of the interelectrode gap, as well as the quality of the treated surface. Keywords: electrochemical treatment, roughness, electrolyte, electrical conductivity, gas filling. [email protected]

Electrochemical Processing of Metal Wastes of Rhenium-Containing Heat-Resistant Nickel Alloys

The paper presents the results of studies of electrochemical processing of large pieces of metal wastes of rhenium-containing heat-resistant nickel alloys (HRNA) with subsequent processing of the products of electrolysis. It shows the possibility of electrochemical processing of large (up to 2 kg) scrap pieces, without preliminary grinding, in sulfuric acid solution with nitric acid addition, under the current density of 500-1000 A/m2, with a temperature of 30-40о С. Up to 80-90% of rhenium and over 90% of nickel, cobalt, chrome and aluminum can be converted into the solution. Tungsten, tantalum and hafnium remain in the anode slime almost completely. Rhenium, nickel and cobalt remaining in the anode slime can be transferred to the solution, when the slime is chemically processed in sulfuric acid solution with nitric acid addition. The cake remaining after chemical decomposition of anode slimes represents a concentrate of refractory rare metals, containing up to 42% W; 18% Ta; 4% Hf. Rhenium is extracted from the combined solutions from anodic decomposition of HRNA wastes, and chemical dissolution of anode slimes, by the known extraction method in the form of the crude ammonium perrhenate (68,9 mас. % Re). After rhenium extraction the raffinate contains considerable quantities of nickel and cobalt, which can be precipitated by the alkali solution in the form of hydroxides to the nickel-cobalt concentrate, containing 31.5% Ni and 4.8% Co.