Arseenin käyttö sinkkitehtaan koboltinpoistoon

Työssä selvitettiin kuparielektrolyysissä syntyvän sivutuotteen, arseenitrioksidin, soveltuvuutta The New Boliden Kokkola Zinc Oy:n sinkkitehtaan liuospuhdistuksen koboltinpoistovaiheeseen. Nykyään sinkkitehtaalla käytetään puhdasta arseenitrioksidia koboltinpoiston apuaineena. Tällä hetkellä kuparielektrolyysin arseenista valmistetaan puunsuoja-aineita. Lainsäädäntö muuttuu siten että tulevaisuudessa kyseisten puunsuoja-aineiden käyttöä tullaan yhä rajoittamaan. Kun puunsuoja-aineiden kulutus vähenee, täytyy syntyvä arseeni varastoida jätealueelle ellei sille löydetä muuta käyttöä. Arseenin varastointitarve ei lisäänny jos kuparielektrolyysistä saatava arseeni voidaan hyödyntää sinkkitehtaalla. Kuparielektrolyysissä syntyvä arseenitrioksidi ei ole puhdasta. Työssä selvitettiin epäpuh-tauksien vaikutusta sinkkitehtaan liuospuhdistuksen koboltinpoistovaiheeseen. Kokeiden olosuhteet pyrittiin yhdenmukaistamaan sinkkitehtaan koboltinpoistovaiheessa vallitsevia olosuhteita vastaaviksi. Kokeissa käytetyillä arseeniliuosten eri epäpuhtaustasoilla ei havaittu olevan selkeää eroa liuospuhdistuskyvyssä. Koetulokset antavat viitteitä siitä, että koboltinpoistoprosessi on oletettua epäherkempi arseeniliuoksen epäpuhtauksien vaikutuksille. Kirjallisuudesta haettiin arseenitrioksidin valmistukseen ja puhdistamiseen liittyvää aineistoa. Valmistusmenetelminä tarkasteltiin valmistusta arseenimalmista ja kuparielektrolyytistä ja puhdistusmenetelminä uudelleenkiteytystä, jäädytys-sulatusprosessia ja ioninvaihtoa. Työssä puhdistettiin kuparielektrolyysin liuospuhdistuksessa syntyvää arseenitrioksidia. Puhdistuslaitteistosta tehtiin alustava prosessisuunnitelma.

The Effect of the Cu:Fe''' Ratio Upon the Current Efficiency in the Electrolysis of a Copper Sulfate Solution Containing Iron Sulfate

It is a well-known fact that, in the electrolysis of a CuSO4 solution containing iron sulfate, using insoluble anodes, with the depletion of copper, the point is finally reached where the current efficiency becomes zero. This decrease in current efficiency is due to the oxidation of the ferrous sulfate to the ferric condition at the anode, by the oxygen liberated. The resulting ferric sulfate diffuses over to the cathode and there dissolves copper from the cathode according to the chemical equation Cu + Fe2 (SO4)3 = CuSO4 + 2FeSO4. This copper, which has been deposited at the cathode by the electric current, is thus redissolved by the Fe2(SO4)3. The solution of the copper causes at the same time a formation of FeSO4 which in turn diffuses over to the anode and is there oxidized to Fe2(SO4)3; and so the cycle continues, using electric current without rendering useful work. E. H. Larison has noted that a definite amount of ferric salts must be reduced to the ferrous condition before all the copper will remain on the cathode; he does not state, however, just what this point is. L. Addicks has plotted the relation between current efficiency and ferric sulphate content. The existence of the results scattered the points more or less, although the decrease in current efficiency with increased ferric sulphate content is clearly indicated. E. T.Kern has likewise noted that the smaller the amount of copper in the solution, the greater is the reduction of current efficiency. In this work, therefore, it was desired to determine what amount of ferric iron was permissible in a copper sulfate solution of definite concentration before the current efficiency would drop to zero, and what, if any, was the effect of definite Cu:Fe’’’ratio upon the current efficiency of the electrolysis.

The Recovery of Copper in Sulphide Ores by Roasting, Leaching, and Electrolysis

Sulphide ores of copper are insoluble in dilute sulphuric acid leaching solutions, but a very high extraction can be obtained if the copper ore is in the oxidized condition. The problem is to convert the sulphide into the oxide form. This can be done by giving the sulphide ore an oxidizing-sulphatizing roast. Copper sulphate is soluble in water, so acid will be saved in the leaching process if copper sulphate is present. The iron in the copper sulphide ores is present as pyrite, or in combinations as bornite, or chalcopyrite.

The Effect of the Fe2: Fe3 Ratio upon the Current Efficiency in the Electrolysis of a Copper Sulfate Solution Containing Iron Sulfate

In the treatment of copper ores by hydro-electro-metallurgical methods, not only is copper deposited, but other metals are also dissolved. In practice it has been found* that iron, under certain conditions, causes the copper to deposit on the cathode as a nonadherent precipitate and also that the iron in solution causes a great decrease in current efficiency, es­pecially when the electrolysis is conducted by operating with a higher current density at the cathode than at the anode. The present investigation deals with the effects of the two valences of iron on the current efficiency and endeavors to determine whether or not there is a ratio of the two at which point the efficiency becomes zero or approaches it.

Roasting and Leaching Bulk Copper-Zinc Sulfide Concentrates with the Subsequent Recovery of the Metals by Electrolysis

The aim of this research was to investigate the possibilities of roasting and leaching a bulk copper-zinc sulfide concentrate, and the subsequent separation of the metals from the leach solution by electro­lytic deposition.

Electrodeposition of copper on titanium wires: Taguchi experimental design approach

Electrodeposition of thin copper layer was carried out on titanium wires in acidic sulphate bath. The influence of titanium surface preparation, cathodic current density, copper sulphate and sulphuric acid concentrations, electrical charge density and stirring of the solution on the adhesion of the electrodeposits was studied using the Taguchi statistical method. A L(16) orthogonal array with the six factors of control at two levels each and three interactions was employed. The analysis of variance of the mean adhesion response and signal-to-noise ratio showed the great influence of cathodic current density on adhesion. on the contrary, the other factors as well as the three investigated interactions revealed low or no significant effect. From this study optimized electrolysis conditions were defined. The copper electrocoating improved the electrical conductivity of the titanium wire. This shows that copper electrocoated titanium wires could be employed for both electrical purpose and mechanical reinforcement in superconducting magnets. (C) 2008 Elsevier B.V. All rights reserved.

Formation of TiO2 photoanodes by simultaneous electrophoretic deposition of anatase and rutile particles for photoassisted electrolytic copper ions removal

The influence of Anatasa/Rutile ratio on TiO2 films, grown by electrophoretic deposition was studied in the photoassisted electrolytic copper ions removal from cyanide solutions. The proper dispersant dosage allowing the simultaneous electrophoretic deposition of Anatase and Rutile was chosen based on electrokinetic measurements; evidenced by the XRD spectra of the formed films. The evaluation of films photoassisted electrolytic copper ion removal showeds that it is possible to enhance the activity of Anatase films by adding some Rutile exploiting the synergetic interaction between these two materials, achieve by its proper deposition.

Optimization of electroless copper plating on polyethylene films modified by surface grafting of vinyl ether of monoethanolamine

Metallized plastics have recently received significant interest for their useful applications in electronic devices such as for integrated circuits, packaging, printed circuits and sensor applications. In this work the metallized films were developed by electroless copper plating of polyethylene films grafted with vinyl ether of monoethanoleamine. There are several techniques for metal deposition on surface of polymers such as evaporation, sputtering, electroless plating and electrolysis. In this work the metallized films were developed by electroless copper plating of polyethylene films grafted with vinyl ether of monoethanoleamine. Polyethylene films were subjected to gamma-radiation induced surface graft copolymerization with vinyl ether of monoethanolamine. Electroless copper plating was carried out effectively on the modified films. The catalytic processes for the electroless copper plating in the presence and the absence of SnCl2 sensitization were studied and the optimum activation conditions that give the highest plating rate were determined. The effect of grafting degree on the plating rate is studied. Electroless plating conditions (bath additives, pH and temperature) were optimized. Plating rate was determined gravimetrically and spectrophotometrically at different grafting degrees. The results reveal that plating rate is a function of degree of grafting and increases with increasing grafted vinyl ether of monoethanolamine onto polyethylene. It was found that pH 13 of electroless bath and plating temperature 40°C are the optimal conditions for the plating process. The increasing of grafting degree results in faster plating rate at the same pH and temperature. The surface morphology of the metallized films was investigated using scanning electron microscopy (SEM). The adhesion strength between the metallized layer and grafted polymer was studied using tensile machine. SEM photos and adhesion measurements clarified that uniform and adhered deposits were obtained under optimum conditions.

Electrodeposition of copper on titanium wires: Taguchi experimental design approach

Electrodeposition of thin copper layer was carried out on titanium wires in acidic sulphate bath. The influence of titanium surface preparation, cathodic current density, copper sulphate and sulphuric acid concentrations, electrical charge density and stirring of the solution on the adhesion of the electrodeposits was studied using the Taguchi statistical method. A L(16) orthogonal array with the six factors of control at two levels each and three interactions was employed. The analysis of variance of the mean adhesion response and signal-to-noise ratio showed the great influence of cathodic current density on adhesion. on the contrary, the other factors as well as the three investigated interactions revealed low or no significant effect. From this study optimized electrolysis conditions were defined. The copper electrocoating improved the electrical conductivity of the titanium wire. This shows that copper electrocoated titanium wires could be employed for both electrical purpose and mechanical reinforcement in superconducting magnets. (C) 2008 Elsevier B.V. All rights reserved.

High current-density anodic electro-dissolution in flow-injection systems for the determination of aluminium, copper and zinc in non-ferroalloys by flame atomic absorption spectrometry

An automatic Procedure with a high current-density anodic electrodissolution unit (HDAE) is proposed for the determination of aluminium, copper and zinc in non-ferroalloys by flame atonic absorption spectrometry, based on the direct solid analysis. It consists of solenoid valve-based commutation in a flow-injection system for on-line sample electro-dissolution and calibration with one multi-element standard, an electrolytic cell equipped with two electrodes (a silver needle acts as cathode, and sample as anode), and an intelligent unit. The latter is assembled in a PC-compatible microcomputer for instrument control, and far data acquisition and processing. General management of the process is achieved by use of software written in Pascal. Electrolyte compositions, flow rates, commutation times, applied current and electrolysis time mere investigated. A 0.5 mol l(-1) HNO3 solution was elected as electrolyte and 300 A/cm(2) as the continuous current pulse. The performance of the proposed system was evaluated by analysing aluminium in Al-allay samples, and copper/zinc in brass and bronze samples, respectively. The system handles about 50 samples per hour. Results are precise (R.S.D < 2%) and in agreement with those obtained by ICP-AES and spectrophotometry at a 95% confidence level.

Preparation, characterization and electrochemical studies of dinuclear copper(II) complexes with pseudohalides and bidentate amines on platinum electrode in acetonitrile

The complexes: [Cu(N 3) 2(N,N-diEten)] 2, [Cu(N 3) 2(tmeen)] 2, [Cu(N 3)(NCO)(N,N-diEten)] 2, [Cu(N 3) 2(N,N′-diMeen)] 2 and [Cu(N 3)(NCO)(tmeen)] 2 were prepared, characterized and their electrochemical behavior was investigated by cyclic voltammetry and controlled potential electrolysis. Cyclic voltammograms for all complexes studied are similar and exhibit one pair of current peaks in the range of -0.65 to +0.0 V. The number of electrons obtained from controlled potential electrolysis at ca. -0.55 V for all compounds was 1.8 ≤ n ≤ 2.1, indicating that both copper(II) metallic centres in the molecule were reduced to copper (I). Comparing the peak potential values for these complexes one can observe that the redox process corresponding to copper(II)/copper(I) couple is slightly influenced by the σ-basicity of the ligands. © 1997 Soc. Bras. Química.

Minimization of lead and copper interferences on spectrophotometric determination of cadmium using electrolytic deposition and ion-exchange in multi-commutation flow system

A new strategy for minimization of Cu2+ and Pb2+ interferences on the spectrophotometric determination of Cd2+ by the Malachite green (MG)-iodide reaction using electrolytic deposition of interfering species and solid phase extraction of Cd2+ in flow system is proposed. The electrolytic cell comprises two coiled Pt electrodes concentrically assembled. When the sample solution is electrolyzed in a mixed solution containing 5% (v/v) HNO3, 0.1% (v/v) H2SO4 and 0.5 M NaCl, Cu2+ is deposited as Cu on the cathode, Pb2+ is deposited as PbO2 on the anode while Cd2+ is kept in solution. After electrolysis, the remaining solution passes through an AG1-X8 resin (chloride form) packed minicolumn in which Cd2+ is extracted as CdCl4/2-. Electrolyte compositions, flow rates, timing, applied current, and electrolysis time was investigated. With 60 s electrolysis time, 0.25 A applied current, Pb2+ and Cu2+ levels up to 50 and 250 mg 1-1, respectively, can be tolerated without interference. For 90 s resin loading time, a linear relationship between absorbance and analyte concentration in the 5.00-50.0 μg Cd 1-1 range (r2 = 0.9996) is obtained. A throughput of 20 samples per h is achieved, corresponding to about 0.7 mg MG and 500 mg KI and 5 ml sample consumed per determination. The detection limit is 0.23 μg Cd 1-1. The accuracy was checked for cadmium determination in standard reference materials, vegetables and tap water. Results were in agreement with certified values of standard reference materials and with those obtained by graphite furnace atomic absorption spectrometry at 95% confidence level. The R.S.D. for plant digests and water containing 13.0 μg Cd 1-1 was 3.85% (n = 12). The recoveries of analyte spikes added to the water and vegetable samples ranged from 94 to 104%. (C) 2000 Elsevier Science B.V.

Effect of Impurities upon Current Efficiency in the Electrolysis of Zinc Sulphate Solution

There are many elements which are detrimental to the current efficiency in the electrolysis of zinc sulphate solution. Fortunately the majority of these elements are easily removed in the purification process and cause no further trouble. The elements that are likely to cause trouble in ordinary plant operations are antimony, arsenic, cobalt, nickel, manganese and germanium. The following tests were made to determine the mutual effect on the current efficiency when several of the impurities were present in the electrolyte.

Electrolysis of Molten Mixtures of Galena and Lead Chloride.

Electrolysis of molten mixtures of lead chloride and galena was carried out under various conditions of temperature, time, composition, and current densities; without a diaphram, and with various diaphrams. Continuous runs, with necessary additions of lead sulfide and lead chloride to maintain a melt of the proper composition, were attempted on a small scale.

The Electrolytic Recovery of Copper and Zinc from Scrap Brass with Special Reference to Lead-Bearing Brass.

Several methods have been investigated, with some success, for treating scrap brass to recover copper and zinc, either as pure metals or as salts of the metals. One of the more promising of these methods is electrolysis in sulfate solution for the recovery of pure copper and zinc.