Anode Sludge Research Articles

Electrical characterisation of cordierite bodies containing Al-rich anodising sludge

Al-rich sludge produced from industrial anodising and surface treatment processes had been tested in the fabrication of cordierite-based materials, by using unidirectional dry pressing and extrusion as shaping techniques. Mixtures with commercial sand and magnesium-containing materials, like ball clay, and talc were prepared in order to achieve interesting final refractory and/or electrical insulating compositions. Microstructural changes upon sintering and crystalline phase evolution are detailed and their relationship with the electrical behaviour is now studied, by the use of impedance spectroscopy.

Application of Metalfix Chelamine prior to the determination of noble metals by the inductively coupled plasma atomic emission spectrometry

Metalfix Chelamine chelating resins of two different bead sizes (150–300 and 40–80 μm) were examined and compared regarding their application for sorption of Au, Ir, Pd, Pt, Rh and Ru ions from medium of HCl, HNO 3 and mixtures of HCl and HNO 3. The quantitative enrichment of Au, Ir, Pd and Pt was established for the resin of 150–300 μm particle size and for solutions acidified with HCl and HNO 3 (3:1) up to the concentration of 0.50 mol l −1. In the case of Rh and Ru, the uptake of these metals by the resin was lower than 50%. For the elution, solutions of different reagents, i.e. HCl, HNO 3, KCN, KI, KSCN and (NH 2) 2CS, were studied with respect to the complete release of the analytes retained by the resin. In addition, influence of various base metals, i.e. Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, on the retention of the noble metals was investigated. Under the selected conditions for the retention and elution of Au, Ir, Pd and Pt, the analytical performance of the proposed pre-concentration procedure was evaluated and it was applied to the determination of these noble metals in anodic sludge sample.

Coalescence extraction of silver(I) using the temperature-induced phase separation (TIPS) process

The extraction of silver(I) from solutions by three dinitrile solvents has been investigated. The methodology is based on the temperature-induced phase separation (TIPS) of silver(I) with malononitrile (MN), succinonitrile (SCN), and glutaronitrile (GN) solvents in absence of chelating agent. Three dinitrile solvents MN, SCN, and GN are able to participate in coalescence extraction. Analysis silver(I) content in both organic and aqueous phases was accomplished by inductively coupled plasma (ICP) spectrophotometry. All three systems were highly efficient in extraction of silver (>98%) and extraction times were fast (few minutes). The quantitatively extraction efficiency is achieved because of formation of complexes of soft cation (silver) with dinitrile solvents. The selectivity of silver ion extraction from aqueous solutions containing alkali, alkaline earth (at M n+ /silver mole ratio of 100), transition and some heavy metal ions (at mole ratio of 5) was investigated and it was found that with the exception of Hg 2+ and Cu 2+ none of cations used interfered with the silver ion extraction. The proposed method has been applied to extraction and determination of silver in contaminated anodic sludge. The extraction efficiency for three replicates after 2 min was 98% with R.S.D. = 1.1%.

Extrusion of Recycled Pastes Based on Al-Rich Anodising Sludge

Al-rich anodising sludge has been tested as main component of alumina, mullite or cordierite based refractory materials and bodies have been processed by using different techniques, such as slip casting, dry pressing and extrusion. The success of the last technique is strongly dependent on the materials composition and proper additives, such as plasticizers and lubricants. Operation conditions might be also adjusted within certain limits and includes the design and size of the die, the flowing speed, and as consequence the applied pressure. In the current work, cordierite hole-tubes of different diameters had been processed by extrusion. The effect of mentioned parameters was evaluated based on the Benbow’s equation and ultimate extrusion quality of samples was estimated.

Mullite-Alumina Refractory Ceramics Obtained from Mixtures of Natural Common Materials and Recycled Al-Rich Anodizing Sludge

This work describes attempts to reuse Al-rich sludge produced from industrial anodizing and surface treatment processes in the fabrication of mullite-based refractory materials. The complete characterization of the residue is reported, including physical and compositional parameters. Mixtures with common natural silica-containing materials, like ball clay, kaolin, and/or diatomite were prepared in order to achieve interesting final fired compositions. Rheological characterization of the suspensions, their slip casting performance, the thermal behavior of the consolidated bodies, and crystalline phase evolution are also detailed. From the knowledge acquired, pretreatment operations have been suggested to facilitate the recycling of the Al-rich sludge and to improve the characteristics of mullite-based materials.

A pyrometallurgical alternative: The refining electrolysis of lead and solder

In refining electrolysis in hexafluorosilic acid with current densities of 100 A/m2, it is possible to separate bismuth and antimony from prerefined lead bullion. Pure lead with less than 50 ppm bismuth and less than 100 ppm antimony was deposited at the cathode. The current efficiency was 99%, and the specific energy consumption was 30–40 kWh/t. Under the same conditions, a lead-tin alloy with less than 300 ppm antimony can be produced by refining a Pb−Sn−Sb alloy with 30% tin and up to 5% antimony. In this case, antimony remains in the anode sludge. Because of the high amount of anode sludge, the strong adhesion of the sludge on the anode surface, and its physical properties in the case of high antimony contents (i.e., more than 5% antimony in the anodes), some differences in the usual electrolysis technology are necessary to guarantee a long-term, stable, and trouble-free electrolysis. The tendency of anode passivation can be reduced by using a periodic current reversal technique. This technique results in a smaller amount of anode sludge, a reduced loss of lead in the anode sludge, and lower anodic polarization values.

4666514 Hydrometallurgical process for recovering silver from copper-electrolysis anode sludge : Josef Bertha, Brixlegg, Austria assigned to Austria Metall Aktiengesellschaft

4666514 Hydrometallurgical process for recovering silver from copper-electrolysis anode sludge : Josef Bertha, Brixlegg, Austria assigned to Austria Metall Aktiengesellschaft

Determination of palladium in silver, copper, selenium and anode sludge by atomic-absorption spectrometry after extraction of tri-n-octylmethylammonium tetrabromopalladate

Palladium (>0.5 μg ) is extracted as tri-n-octylmethylammonium tetrabromopalladate into n-butyl acetate and determined by flame atomic-absorption spectrometry of the extract. Extraction from hydrochloric or hydrobromic acid solution with tri-n-octylamine is also discussed. The method is applied to the determination of palladium in silver, copper, selenium and anode sludge.

Selenium as a Health Hazard

IT is USEFUL to recall that selenium is a congener of sulphur, tellurium and arsenic. Selenium is a rare element, being slightly more abundant than gold, but is found neither in large quantities nor in the elemental form. The principal sources are flue-dusts from sulphuric acid works using seleniferous pyrites, flue-dusts from smelting processes and particularly the anode sludge of the electrolytic refinement of copper which may contain up to 15 per cent. Its current price is £12 per lb. Traces of selenium occur in rocks or soils all over the world. The mesozoic soils of the great plains of the U.S.A. (Dakota, Montana, Wyoming) have concentrations up to 30 parts per million, and plants growing in such soils absorb selenium which may subsequently be ingested by animals and humans in amounts sufficient to give rise to chronic and sometimes to fatal poisoning. Wheat grown on soil containing 30 parts per million may be toxic even after milling, though the toxicity is mainly associated with the protein moiety. Cattle and horses grazing on soils with concentrations of 10-20 parts per million may be the subjects of chronic poisoning. This, in horses, is shown by a loss of mane and tail hair and by abnormal hoof growth. In more severe cases, horses may develop blind staggers, erosion of bone, focal neurosis of liver, with cirrhosis—if of long standing—and death from respiratory failure.' The danger of seleniferous soils is minimised by high rainfall and possibly by the presence of arsenic, which in traces may inhibit the toxic effects of selenium. There is little evidence that selenium of vegetable origin is ingested in injurious quantities by man, but it can be found concentrated in the lungs, liver, kidney and spleen. Normal urine contains minute amounts, the principal source of which is peas and beans. Selenium intake predisposes to dental caries; the garlicky odour of the breath is due to dimethyl selenide. The industrial uses of selenium have increased rapidly in recent years. The common commercial forms are grey metallic selenium and selenium dioxide. These are used in 1, rectifiers, to convert an alternating current to direct as required for battery charging or electrolytic processes,