The effect of fireside deposits on kraft recovery boiler superheater corrosion

Abstract In kraft pulp mills, the spent pulping liquor is concentrated and used as fuel in the recovery boiler. Extensive deposits are formed in the upper section of the boiler due to the very high ash content of the fuel and the volatile nature of the ash. Deposits are composed of Na2SO4, Na2CO3, NaCl, some potassium salts and reduced sulphur compounds. Chloride and potassium salts are enriched in the deposits compared to the smelt due to their greater volatility.
Severe corrosion of the superheater tubes in a recovery boiler has been traced to three factors: a non-uniform temperature profile in the flue gas, relatively high operating steam temperatures and high chloride and potassium concentrations in the fireside deposits.
The role of chloride and potassium in superheater corrosion has been explained by increased liquid phase in deposits. Together with corrosion studies, this information has shown that kraft recovery boiler superheater corrosion due to the chloride and potassium enriched deposits can be avoided by proper boiler operation and by judicious superheater and furnace design.
Keywords: Corrosion, Fireside deposits, Recovery boilers, Kraft pulp mills, Chloride, Potassium
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Publication: CIM Bulletin
Author(s): K.M. SARKAR
Keywords: Hydrometallurgy, Uranium recovery, Ion exchange, Fluidized bed, Economic analysis
Issue: 872
Volume: 77
Year: 1984
Text
Summary: Process specifications for classification system design for closed circuit grinding are identified. A computer-assisted, mass balance procedure for estimation of material size distributions and required hydrocyclone separation performance is presented.
Publication: CIM Bulletin
Author(s): R.E. MclVOR
Keywords: Mineral processing, Material balance, Grinding circuit, Hydrocyclones, Classifiers
Issue: 872
Volume: 77
Year: 1984
Text
Summary: The effectiveness of two thio compounds for copper sulphide depression in molybdenite flotation has been examined with batch bench scale tests.
Both thioglycollate and trithiocarbonate proved to be good depressants producing results similar to those for cyanide and hydrosulphide. Ferrocyanide was ineffective on the sample material tested.
The depressing effect of thioglycollate was readily reversed by an addition of xanthate.
Publication: CIM Bulletin
Author(s): GORDON E. AGAR
Keywords: Mineral processing, Flotation, Copper sulphides, Sodium cyanide, Ferrocyanide, Sodium hydrosulphide
Issue: 872
Volume: 77
Year: 1984
Text
Summary: Concentrate dewatering operations have a significant influence on the economics of base metal beneficiation. The expenditures for energy and labour per tonne of product are high. The relatively low efficiencies of standard techniques present inducements for process modifications. Development efforts at several Noranda concentrators led to process changes which improved productivity, namely, agitated pulp storage in large vessels, process automation and pressure filtration.
Publication: CIM Bulletin
Author(s): K.V. KONIGSMANN
Keywords: Mineral processing, Dewatering, Pulp storage, Flotation, Pressure filter, Concentrates, Automation
Issue: 872
Volume: 77
Year: 1984
Text
Summary: Canadian income tax legislation contains a number of provisions which serve to facilitate the structuring of business arrangements, including mineral resource ventures. These rules are often fairly complex and not easily understood. This article attempts to explain in plain and understandable language the mechanics and benefits of one of the more frequently encountered provisions, the 'Section 85 election".
Publication: CIM Bulletin
Author(s): ROBERT B. PARSONS
Issue: 872
Volume: 77
Year: 1984
Text
Summary: The principal objective of this study was to verify a certain number of mineralogical hypothesis which could explain the important variations observed in the performances of the B grinding and flotation circuit of the No. 1 concentrator at Mines Gaspe. Six series of samples obtained from a sampling campaign performed in the summer of 1980 have been studied. The capacity of the grinding circuit seems mainly influenced by the variations of the mineralogical and textural properties of the ore....
Publication: CIM Bulletin
Author(s): M.A. BÉRUBÉ
Keywords: Flotation process, Grinding, Copper carbonates, Copper sulphides, Mineral liberation
Issue: 872
Volume: 77
Year: 1984
Text
Summary: Rocks of the Whitewater Group (Aphebian age) occur within the Sudbury Basin and consist of three formations which are, from oldest to youngest: Onaping, heterolithic breccias /lus an igneous-textured component; Onwatin, argillite and silt-stone; and Chelmsford, greywacke with minor argillite with silts tone. Mineralization in these rocks is as follows:1) Sulphides are disseminated throughout the Onaping Formation. Pyrrhotite, the major sulphide mineral, occurs mainly as fragments; other...
Publication: CIM Bulletin
Author(s): D.H. ROUSELL
Keywords: Mineral exploration, Sudbury Basin, Sulphide deposits, Pyrrhotite fragments, Sedimentary exhalative deposits, Quartz veins, Base metals, Anthraxolite, Meteorite impact
Issue: 872
Volume: 77
Year: 1984
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