Thermal behaviour of chromium electroplating sludge.
Galvanic sludge is classified as a hazardous waste and incineration is one of the techniques used for its treatment. The aim of this work is to study the thermal behavior of a galvanic sludge which contains only chromium as a restriction metal. Simultaneous DTA/TG coupled with mass spectrometer tests were performed to characterize the thermal behavior of the sludge. Besides thermal analysis, sludge samples were heated in a specially designed furnace and these samples were submitted to X-ray diffraction. Vapor from the heated sludge was condensed and the particles were analyzed by EDS microprobe coupled in a scanning electron microscope. The slag formed after the calcination of the galvanic sludge was mainly composed of a mixture of calcium phosphate and fluoride. and minor concentrations of metals. A total weight loss of 34% was observed. The greatest part of this weight loss corresponds to CO2, H2O and SO2. H2O is liberated in the temperature range of 500-1,250 degrees C. CO2 in the range of 500-750 degrees C and SO2 near 1,000 degrees C. Chromium evaporation was not observed in relevant quantities, about 99.6% of the Cr remained incorporated in the slag.
Espinosa
D C
DC
Department of Metallurgical and Materials Engineering, University of São Paulo, Brazil.
Tenório
J A
JA
D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry; D002124:Calcium Fluoride / Q000032:analysis; D002130:Calcium Phosphates / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis; D002857:Chromium / Q000032:analysis / Q000737:chemistry*; D004595:Electroplating; D006256:Hazardous Waste / Q000032:analysis*; D006358:Hot Temperature; D017745:Incineration; D007220:Industrial Waste / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D013057:Spectrum Analysis; D013458:Sulfur Dioxide / Q000032:analysis; D014961:X-Ray Diffraction
D000393:Air Pollutants; D002130:Calcium Phosphates; D006256:Hazardous Waste; D007220:Industrial Waste; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; D002857:Chromium; D013458:Sulfur Dioxide; D002245:Carbon Dioxide; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous; D002124:Calcium Fluoride