Control of the acidic aerosol resulting from electrowinning operations

Abstract As part of a study to evaluate factors affecting tankroom air quality, the mechanism of aerosol generation from bursting bubbles in electrowinning operations has been investigated. Typically 2 to 3 mg/m2.s are produced in zinc tankrooms. Analysis shows that the rate of production of film drops (geometric mean diameter ~ 2 fim) increases with decreasing bubble size, and that jet droplets (geometric mean diameter —20 fj.m) are not produced with gas bubble larger than ~ 4 mm. Both mechanisms of drop formation and current efficiency are affected by surface active agents, with an over-all reduction in emission of up to 60% to 70% being achievable. A source control system which does not adversely affect electrolyte properties is always preferred, and coalescence of all gas bubbles in to a continuous stream of gas at a single point on the electrolyte surface would eliminate aerosol emissions. This objective was the basis for design of a coalescence device which, in laboratory tests, reduced the emission rate by over 95%.
The control device fits over the electrodes in the electrowinning cell and is partially immersed in the electrolyte. A number of changes in the design which resulted in significant improvement in the performance of the device are reported.
Field tests have shown that only about 75% of the aerosol below 10 turn can be eliminated by coalescence. The remainder (up to 95% of the total) is controlled by coalescence of droplets, by impaction on the exposed collector surface and gravitational settling.
The device does not interfere with operation of the tankroom, handles the effect of surges in power during harvesting, and is simple and inexpensive to maintain.
Keywords: Air quality, Electrowinning, Coalescence, Health, Safety, Environmental control
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Summary: Smoky River Coal Limited has successfully completed a major program involving the pattern rock anchoring of a high, steeply-dipping footwall slope. The slope dips at approximately 65 to 70 degrees to the north, is benched for the upper 200 feet, is supported with rock anchors for another 240 feet, and is unsupported at the pit bottom. In addition to the height and steepness, several structural features including shears, rolls and stratigraphic pinchouts complicate footwall stability.
This...
Publication: CIM Bulletin
Author(s): DAVID A. FAWCETT, PETER L SHEEHAN, DENNIS C. MARTIN
Keywords: Rock mechanics, Smoky River Coal Limited, Footwall anchoring, Engineering geology, Anchor installation, Instrumentation.
Issue: 915
Volume: 81
Year: 1988
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Summary: Surface crown pillars are important Canadian mining structures. Mines operating in the Canadian Shield usually have several, forming a first line of protection from surface elements.
Detailed technical information from twenty-four Canadian hard rock mines show that the deposits dip steeply and are generally either single or multiple veins. Considerable overburden usually cap the deposits. The rock mass is often altered and intersected by important discontinuities.
The designs for these types...
Publication: CIM Bulletin
Author(s): M.C. BETOURNAY, S. MANTEL, D. LESSARD
Keywords: Rock mechanics, Surface crown pilliars Pillar design, Case studies, Underground mining
Issue: 915
Volume: 81
Year: 1988
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Summary: The development and testing of a simple low-cost gauge for measurement of tension in a cable bolt grouted in a borehole are presented. Its principle is based on a resistance wire which is wound on a 70 cm length into the spiral grooves of the wire strand cable bolt. Readings are then taken by a robust automatic data logger with a several day autonomy or by a portable readout. In order to have a complete profile of tension along the cable bolt, a number of tension gauges can be installed along...
Publication: CIM Bulletin
Author(s): P. CHOQUET, F. MILLER
Keywords: Rock Mechanics, Instrumentation, Monitoring, Steel cable, Tendon, Anchor, Cable bolt, Rock support, Slope stability, Ore dilution, Mining technology, Underground mining.
Issue: 915
Volume: 81
Year: 1988
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Summary: Aluminum alloy structural components for aircraft designed prior to the early 1970s, were machined from 2024, 7075 and 7079 plate, bar and forgings in either the T3xxx of the T6xxx tempers. Protective treatments for these parts consisted of chromic acid anodizing and alkyd zinc chromate primer, plus a nitrocellulose lacquer for exterior parts.
The major service problem with these parts was the frequent occurrence of exfoliation corrosion and stress corrosion cracking (S.C.C.). Therefore, 2024...
Publication: CIM Bulletin
Author(s): L. SALNAIS
Keywords: Materials engineering, Corrosion, Metallurgy, Coatings, Aerospace materials, Metals.
Issue: 915
Volume: 81
Year: 1988
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Summary: The access tunnels for the Donkin-Morien Mine in Cape Breton, Nova Scotia, comprise (wo parallel tunnels driven through a sedimentary sequence of sandstone, siltstone and mudstone to intersect the Harbour Coal Seam under the Atlantic Ocean, approximately 3.5 km offshore (Fig. 1). The No. 2 tunnel was driven a total distance of 3579 m using a 7.6 m diameter Lovat full-face tunnel boring machine (TBM) and was supported by steel sets. The No. 3 tunnel was initially driven a distance of 1027 m...
Publication: CIM Bulletin
Author(s): J.L GILBY, C.M.K. YUEN, T.R.C. ASTON
Keywords: Rock mechanics, Tunnel boring, Research programs, Instrumentation programs, Donkin-Morien Mine.
Issue: 915
Volume: 81
Year: 1988
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Summary: A regional till sampling program in the Upsalquitch Forks-Tetagouche Lakes area, centred some 70 km west of the city of Bathurst, has proven an effective method for gold exploration in the heavily glaciated interior of northern New Brunswick. Prospecting activities within this area over the past three years, have led to the discovery of several gold occurences associated with quartz-carbonate alteration in a variety of intrusive rock types emplaced along major fault zones.
Quaternary mapping...
Publication: CIM Bulletin
Author(s): A.G. PRONK, D.M. BURTON
Keywords: Till geochemistry, Gold, Exploration, Bedrock geology, Mineral occurances, Quarternary geology.
Issue: 915
Volume: 81
Year: 1988
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