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J. E. Dutrizac - One of the best experts on this subject based on the ideXlab platform.
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Hematite formation from Jarosite type compounds by hydrothermal conversion
Canadian Metallurgical Quarterly, 2013Co-Authors: J. E. Dutrizac, Alba SunyerAbstract:AbstractThe hydrothermal conversion of K Jarosite, Pb Jarosite, Na Jarosite, Na–Ag Jarosite, AsO4 containing Na Jarosite and in situ formed K Jarosite and Na Jarosite to hematite was investigated. Potassium Jarosite is the most stable Jarosite species. Its conversion to hematite in the absence of Fe2O3 seed occurred only partially after 5 h reaction at >240°C. In the presence of Fe2O3 seed, the conversion to hematite was nearly complete within 2 h at 225°C and was complete at 240°C. The rate of K Jarosite precipitation, in situ at 225°C in the presence of 50 g L−1 Fe2O3 seed, is faster than its rate of hydrothermal conversion to hematite. In contrast, complete conversion of either Pb Jarosite or Na–Pb Jarosite to hematite and insoluble PbSO4 occurs within 0·75 h at 225°C in the presence of 20 g L−1 Fe2O3 seed. Dissolved Fe(SO4)1·5 either inhibits the conversion of Pb Jarosite or forms Pb Jarosite from any PbSO4 generated. The hydrothermal conversion of Na–Ag Jarosite to hematite was complete within 0·75 h...
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The Behaviour of Gallium During Jarosite Precipitation
Canadian Metallurgical Quarterly, 2013Co-Authors: J. E. Dutrizac, T.t. ChenAbstract:Jarosite precipitation provides an effective means of eliminating thallium from zinc processing circuits, and a systematic study of the extent and mechanism of thallium removal during the precipitation of ammonium, sodium, and potassium Jarosites was carried out. Thallium (as Tl+) substitutes for the “alkali” ion in the Jarosite structure. Nearly ideal Jarosite solid solutions are formed with potassium, but thallium is preferentially precipitated relative to either ammonium or sodium. Approximately 80 pct of the dissolved thallium precipitates during the formation of ammonium Jarosite; the extent of thallium removal is virtually independent of thallium concentrations in the 0 to 3000 mg/L Tl range and of the presence of 75 g/L of dissolved Zn. Although the deportment of thallium is nearly independent of (NH4)2SO4 or Na2SO4 concentrations >0.1 M, the precipitates made from more dilute media are relatively enriched in thallium. Likewise, the precipitates made from dilute ferric ion media are also Tl-rich. Low solution pH values or low temperatures both significantly reduce the amount of Jarosite formed, but the precipitates made under these conditions are enriched in thallium. Furthermore, because thallium Jarosite is more stable than the ammonium or sodium analogues, the initially formed precipitates are consistently Tl rich. The presence of Jarosite seed accelerates the precipitation reaction, but dilutes the thallium content of the product. The results suggest that most of the thallium in a hydrometallurgical zinc circuit could be selectively precipitated in a small amount of Jarosite, by carrying out the precipitation reaction for a short time in the absence of seed and from solutions having low alkali concentrations.
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FACTORS AFFECTING THE INCORPORATION OF COBALT AND NICKEL IN Jarosite-TYPE COMPOUNDS
Canadian Metallurgical Quarterly, 2013Co-Authors: J. E. Dutrizac, T.t. ChenAbstract:Abstract Laboratory studies have shown that minor amounts of cobalt and nickel are structurally incorporated in sodium Jarosite, potassium Jarosite and ammonium Jarosite and that the extent of incorporation increases as the concentration of dissolved cobalt or nickel increases. Potassium Jarosite incorporates more cobalt or nickel (∼1% Co or Ni) than does sodium Jarosite or ammonium Jarosite (∼0.4% Co or Ni). Elevated temperatures increase the incorporation of Co or Ni in the Jarosite precipitates, but the increase is modest. Increasing concentrations of Na2SO4, K2SO4 or (NH4)2SO4 result in an increase in the Co and Ni contents of the Jarosite precipitates. The extent of Co or Ni incorporation also increases as the pH of the synthesis solution increases. In contrast, elevated concentrations of ferric sulphate reduce the extent of Co or Ni incorporation in the Jarosite precipitates. The above parametric dependencies suggest that Co(II) and Ni(II) substitute to a limited extent for Fe(III) in the Jarosite s...
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Hematite formation from Jarosite type compounds by hydrothermal conversion
Canadian Metallurgical Quarterly, 2012Co-Authors: J. E. Dutrizac, Alba SunyerAbstract:The hydrothermal conversion of K Jarosite, Pb Jarosite, Na Jarosite, Na-Ag Jarosite, AsO(4) containing Na Jarosite and in situ formed K Jarosite and Na Jarosite to hematite was investigated. Potassium Jarosite is the most stable Jarosite species. Its conversion to hematite in the absence of Fe(2)O(3) seed occurred only partially after 5 h reaction at >240 degrees C. In the presence of Fe(2)O(3) seed, the conversion to hematite was nearly complete within 2 h at 225 degrees C and was complete at 240 degrees C. The rate of K Jarosite precipitation, in situ at 225 degrees C in the presence of 50 g L(-1) Fe(2)O(3) seed, is faster than its rate of hydrothermal conversion to hematite. In contrast, complete conversion of either Pb Jarosite or Na-Pb Jarosite to hematite and insoluble PbSO(4) occurs within 0.75 h at 225 degrees C in the presence of 20 g L(-1) Fe(2)O(3) seed. Dissolved Fe(SO(4))(1.5) either inhibits the conversion of Pb Jarosite or forms Pb Jarosite from any PbSO(4) generated. The hydrothermal conversion of Na-Ag Jarosite to hematite was complete within 0.75 h at 225 degrees C in the presence of 20 g L(-1) Fe(2)O(3) seed. The Ag dissolved during hydrothermal conversion and reported to the final solution. However, the presence of sulphur or sulphide minerals caused the reprecipitation of the dissolved Ag. The conversion of AsO(4) containing Na Jarosite at 225 degrees C in the presence of 20 g L(-1) Fe(2)O(3) seed was complete within 2 h, for H(2)SO(4) concentrations,
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The behaviour of phosphate during Jarosite precipitation
Hydrometallurgy, 2010Co-Authors: J. E. Dutrizac, T.t. ChenAbstract:Abstract The behaviour of phosphate during the precipitation of sodium Jarosite and potassium Jarosite was investigated. At 97, 98 or 150 °C, single-phase PO 4 -bearing sodium Jarosite or potassium Jarosite precipitated from Fe(SO 4 ) 1.5 solutions containing less than about 4 g/L PO 4 . Higher PO 4 concentrations resulted in the co-precipitation of other phosphate species. Phosphate is preferentially precipitated relative to sulphate under all conditions. The products formed from solutions having a constant PO 4 concentration and containing > 0.15 M Fe(SO 4 ) 1.5 consisted of PO 4 -bearing sodium Jarosite. The precipitates from more dilute Fe(SO 4 ) 1.5 solutions consisted of an amorphous phase plus sodium Jarosite. Different behaviours were observed when the Fe(SO 4 ) 1.5 / PO 4 ratio of the solutions was kept constant; these precipitates were only PO 4 -bearing sodium Jarosite. At temperatures 4 , only PO 4 -bearing sodium Jarosite was detected. At 98 °C, PO 4 -bearing sodium Jarosite was produced over the pH range from 1.0 to 2.0. At 150 °C, PO 4 -containing potassium Jarosite was produced, but all the precipitates were contaminated with an unknown phosphate species. The precipitates made in predominantly chloride media were similar to those formed under comparable conditions in the all-sulphate systems. Single phase PO 4 -containing sodium Jarosite or potassium Jarosite precipitated from chloride solutions containing 4 , but the precipitates formed from more concentrated PO 4 solutions were contaminated with other phosphate species. Detailed mineralogical studies indicated a limited degree of PO 4 solid solution in both sodium Jarosite and potassium Jarosite, with PO 4 contents of 5–6% being achieved. It seems that the PO 4 3− anion substitutes for SO 4 2− in the Jarosite structure, and that the limited extent of substitution is mostly limited by the different charges on the PO 4 3− and SO 4 2− anions.
T.t. Chen - One of the best experts on this subject based on the ideXlab platform.
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The Behaviour of Gallium During Jarosite Precipitation
Canadian Metallurgical Quarterly, 2013Co-Authors: J. E. Dutrizac, T.t. ChenAbstract:Jarosite precipitation provides an effective means of eliminating thallium from zinc processing circuits, and a systematic study of the extent and mechanism of thallium removal during the precipitation of ammonium, sodium, and potassium Jarosites was carried out. Thallium (as Tl+) substitutes for the “alkali” ion in the Jarosite structure. Nearly ideal Jarosite solid solutions are formed with potassium, but thallium is preferentially precipitated relative to either ammonium or sodium. Approximately 80 pct of the dissolved thallium precipitates during the formation of ammonium Jarosite; the extent of thallium removal is virtually independent of thallium concentrations in the 0 to 3000 mg/L Tl range and of the presence of 75 g/L of dissolved Zn. Although the deportment of thallium is nearly independent of (NH4)2SO4 or Na2SO4 concentrations >0.1 M, the precipitates made from more dilute media are relatively enriched in thallium. Likewise, the precipitates made from dilute ferric ion media are also Tl-rich. Low solution pH values or low temperatures both significantly reduce the amount of Jarosite formed, but the precipitates made under these conditions are enriched in thallium. Furthermore, because thallium Jarosite is more stable than the ammonium or sodium analogues, the initially formed precipitates are consistently Tl rich. The presence of Jarosite seed accelerates the precipitation reaction, but dilutes the thallium content of the product. The results suggest that most of the thallium in a hydrometallurgical zinc circuit could be selectively precipitated in a small amount of Jarosite, by carrying out the precipitation reaction for a short time in the absence of seed and from solutions having low alkali concentrations.
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FACTORS AFFECTING THE INCORPORATION OF COBALT AND NICKEL IN Jarosite-TYPE COMPOUNDS
Canadian Metallurgical Quarterly, 2013Co-Authors: J. E. Dutrizac, T.t. ChenAbstract:Abstract Laboratory studies have shown that minor amounts of cobalt and nickel are structurally incorporated in sodium Jarosite, potassium Jarosite and ammonium Jarosite and that the extent of incorporation increases as the concentration of dissolved cobalt or nickel increases. Potassium Jarosite incorporates more cobalt or nickel (∼1% Co or Ni) than does sodium Jarosite or ammonium Jarosite (∼0.4% Co or Ni). Elevated temperatures increase the incorporation of Co or Ni in the Jarosite precipitates, but the increase is modest. Increasing concentrations of Na2SO4, K2SO4 or (NH4)2SO4 result in an increase in the Co and Ni contents of the Jarosite precipitates. The extent of Co or Ni incorporation also increases as the pH of the synthesis solution increases. In contrast, elevated concentrations of ferric sulphate reduce the extent of Co or Ni incorporation in the Jarosite precipitates. The above parametric dependencies suggest that Co(II) and Ni(II) substitute to a limited extent for Fe(III) in the Jarosite s...
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The behaviour of phosphate during Jarosite precipitation
Hydrometallurgy, 2010Co-Authors: J. E. Dutrizac, T.t. ChenAbstract:Abstract The behaviour of phosphate during the precipitation of sodium Jarosite and potassium Jarosite was investigated. At 97, 98 or 150 °C, single-phase PO 4 -bearing sodium Jarosite or potassium Jarosite precipitated from Fe(SO 4 ) 1.5 solutions containing less than about 4 g/L PO 4 . Higher PO 4 concentrations resulted in the co-precipitation of other phosphate species. Phosphate is preferentially precipitated relative to sulphate under all conditions. The products formed from solutions having a constant PO 4 concentration and containing > 0.15 M Fe(SO 4 ) 1.5 consisted of PO 4 -bearing sodium Jarosite. The precipitates from more dilute Fe(SO 4 ) 1.5 solutions consisted of an amorphous phase plus sodium Jarosite. Different behaviours were observed when the Fe(SO 4 ) 1.5 / PO 4 ratio of the solutions was kept constant; these precipitates were only PO 4 -bearing sodium Jarosite. At temperatures 4 , only PO 4 -bearing sodium Jarosite was detected. At 98 °C, PO 4 -bearing sodium Jarosite was produced over the pH range from 1.0 to 2.0. At 150 °C, PO 4 -containing potassium Jarosite was produced, but all the precipitates were contaminated with an unknown phosphate species. The precipitates made in predominantly chloride media were similar to those formed under comparable conditions in the all-sulphate systems. Single phase PO 4 -containing sodium Jarosite or potassium Jarosite precipitated from chloride solutions containing 4 , but the precipitates formed from more concentrated PO 4 solutions were contaminated with other phosphate species. Detailed mineralogical studies indicated a limited degree of PO 4 solid solution in both sodium Jarosite and potassium Jarosite, with PO 4 contents of 5–6% being achieved. It seems that the PO 4 3− anion substitutes for SO 4 2− in the Jarosite structure, and that the limited extent of substitution is mostly limited by the different charges on the PO 4 3− and SO 4 2− anions.
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The behaviour of phosphate during Jarosite precipitation
Hydrometallurgy, 2010Co-Authors: J. E. Dutrizac, T.t. ChenAbstract:The behaviour of phosphate during the precipitation of sodium Jarosite and potassium Jarosite was investigated. At 97, 98 or 150 ??C, single-phase PO4-bearing sodium Jarosite or potassium Jarosite precipitated from Fe(SO4)1.5 solutions containing less than about 4 g/L PO4. Higher PO4 concentrations resulted in the co-precipitation of other phosphate species. Phosphate is preferentially precipitated relative to sulphate under all conditions. The products formed from solutions having a constant PO4 concentration and containing > 0.15 M Fe(SO4)1.5 consisted of PO4-bearing sodium Jarosite. The precipitates from more dilute Fe(SO4)1.5 solutions consisted of an amorphous phase plus sodium Jarosite. Different behaviours were observed when the Fe(SO4)1.5/PO4 ratio of the solutions was kept constant; these precipitates were only PO4-bearing sodium Jarosite. At temperatures < 170 ??C, in the presence of 1.8 g/L PO4, only PO4-bearing sodium Jarosite was detected. At 98 ??C, PO4-bearing sodium Jarosite was produced over the pH range from 1.0 to 2.0. At 150 ??C, PO4-containing potassium Jarosite was produced, but all the precipitates were contaminated with an unknown phosphate species. The precipitates made in predominantly chloride media were similar to those formed under comparable conditions in the all-sulphate systems. Single phase PO4-containing sodium Jarosite or potassium Jarosite precipitated from chloride solutions containing < 3 g/L PO4, but the precipitates formed from more concentrated PO4 solutions were contaminated with other phosphate species. Detailed mineralogical studies indicated a limited degree of PO4 solid solution in both sodium Jarosite and potassium Jarosite, with PO4 contents of 5-6% being achieved. It seems that the PO4 3- anion substitutes for SO4 2- in the Jarosite structure, and that the limited extent of substitution is mostly limited by the different charges on the PO4 3- and SO4 2- anions. Crown Copyright ?? 2010.
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The behaviour of scandium, yttrium and uranium during Jarosite precipitation
Hydrometallurgy, 2009Co-Authors: J. E. Dutrizac, T.t. ChenAbstract:Abstract The behaviour of scandium, yttrium and uranium during the precipitation of potassium Jarosite and sodium Jarosite was investigated in laboratory experiments. The end-member scandium, yttrium and uranium analogues of potassium Jarosite could not be synthesized from iron-free solutions under the acidic conditions required for Jarosite formation. However, scandium contents as high as 2.70 wt.% Sc were detected in potassium Jarosite precipitates, and supporting mineralogical studies indicate that Sc(III) substitutes for Fe(III) in the Jarosite structure. The extent of Sc incorporation in potassium Jarosite increases slightly as the pH of the solution increases, and this behaviour is consistent with the enhanced hydrolysis of Sc(III) ions at the higher pH values. Nevertheless, the scandium molar partitioning coefficients are only about 0.2, indicating that Fe is preferentially precipitated relative to Sc in acid media. Increasing concentrations of yttrium have little effect on the composition of either potassium Jarosite or sodium Jarosite synthesized at 98 °C from solutions at pH 1.6. Although the yttrium contents increased systematically as the yttrium concentration increased to 8 g/L, the yttrium contents of the potassium Jarosite precipitates were 2 SO 4 concentration. Uranium is not significantly incorporated in Jarosite-type compounds; for example, a sodium Jarosite precipitate made from a solution containing 25 g/L UO 2 SO 4 contained
Janice L. Bishop - One of the best experts on this subject based on the ideXlab platform.
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Mössbauer and Reflectance Spectroscopy of Synthetic Jarosite with Variable Compositions and Temperatures
2006Co-Authors: Y. Rothstein, M. D. Dyar, Janice L. BishopAbstract:Introduction: The Mars Exploration Rover Mossbauer spectroscopy team identified Jarosite, a sulfate which forms in the presence of water, in spectra of a layered outcrop in Meridiani Planum [1]. They made this assignment based on a doublet with quadrupole splitting of ~1.22 mm/s at T=200-280K that was assigned to either Kor Na-Jarosite with the possibility of some Al substituting for Fe in octahedral sites. In order to further characterize this Jarosite at Meridiani and search for Jarosite elsewhere, careful spectroscopic characterization of the Mossbauer parameters of Jarosite over a range of compositions and temperatures is needed, which is the goal of this study. Table 1. Compositions of Synthetic Jarosites
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the visible and infrared spectral properties of Jarosite and alunite
American Mineralogist, 2005Co-Authors: Janice L. Bishop, Enver MuradAbstract:The visible and infrared spectral properties of two natural Jarosite minerals and a suite of synthetic Jarosites and alunite samples are described here. The fundamental stretching and bending vibrations observed in the infrared region for SO 4 2− and OH − are compared with the near-infrared overtones and combinations of these vibrations. Shifts were observed in the SO 4 2− and OH − bands for Al 3+ vs. Fe 3+ at the octahedral sites and K + vs. Na + at the “A” (frequently monovalent) sites. Crystal-field theory bands were observed for Jarosite near 435, 650, and 900–925 nm and were compared to those of iron oxides. Spectral bands near 1.76, 2.17, 2.53, 4.5, 8–10, and 15–24 μm (corresponding to ~5670, 4600, 3970–4150, 2100–2300, 1000–1225, and 420–675 cm −1 , respectively) for alunite and near 0.43, 0.91, 1.85, 2.27, 2.63, 4.9, 8–10, and 15–24 μm (corresponding to ~23 000, 10 990, 5400, 4350–4520, 3800–4150, 1950–2200, 1000–1190, and 440–675 cm −1 , respectively) for Jarosite would be most useful for detecting these minerals using remote sensing on Earth or Mars. These minerals are important indicators of alteration processes, and this study contributes toward combined visible/near-infrared and mid-infrared spectral detection of these two alunite-group minerals.
Clare P Grey - One of the best experts on this subject based on the ideXlab platform.
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insight into the local magnetic environments and deuteron mobility in Jarosite afe3 so4 2 od od2 6 a k na d3o and hydronium alunite d3o al3 so4 2 od 6 from variable temperature 2h mas nmr spectroscopy
Chemistry of Materials, 2011Co-Authors: Ulla Gro Nielsen, Juraj Majzlan, Ivo Heinmaa, Ago Samoson, Clare P GreyAbstract:Detailed insight into the magnetic properties and mobility of the different deuteron species in Jarosites (AFe3(SO4)2(OD)6, A = K, Na, D3O) is obtained from variable-temperature 2H MAS NMR spectroscopy performed from 40 to 300 K. Fast MAS results in high-resolution spectra above the Neel transition temperature (i.e., in the paramagnetic regime). The 2H NMR hyperfine shift (δ), measured as a function of temperature, is a very sensitive probe of the local magnetic environment. Two different magnetic environments are observed: (i) Fe2–OD groups and D3O+ ions in stoichiometric regions of the sample. Here, the δ(2H) values are proportional to the bulk susceptibility and follow a Curie–Weiss law above 150 K. (ii) Fe-OD2 groups and D2O molecules located near the Fe3+ vacancies in the structure. The Fe3+ ions near these vacancies show strong local antiferromagnetic couplings even high above the Neel temperature (of ca. 65 K). The D2O and D3O+ ions located on the Jarosite A site can be distinguished in the 2H NMR ...
Wayde N. Martens - One of the best experts on this subject based on the ideXlab platform.
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Thermal decomposition of hydronium Jarosite (H3O)Fe 3(SO4)2(OH)6
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Ray L Frost, Rachael-anne Wills, Jacob Kloprogge, Wayde N. MartensAbstract:Thermogravimetry combined with mass spectrometry has been used to study the thermal decomposition of a synthetic hydronium Jarosite. Five mass loss steps are observed at 262, 294, 385, 557 and 619°C. The mass loss step at 557°C is sharp and marks a sharp loss of sulphate as SO from the hydronium Jarosite. Mass spectrometry through evolved gases confirms the first three mass loss steps to dehydroxylation, the fourth to a mass loss of the hydrated proton and a sulphate and the final step to the loss of the remaining sulphate. Changes in the molecular structure of the hydronium Jarosite were followed by infrared emission spectroscopy. This technique allows the infrared spectrum at the elevated temperatures to be obtained. Infrared emission spectroscopy confirms the dehydroxylation has taken place by 400 and the sulphate loss by 650°C. Jarosites are a group of minerals formed in evaporite deposits and form a component of the efflorescence. The minerals can function as cation and heavy metal collectors. Hydronium Jarosite has the potential to act as a cation collector by the replacement of the proton with a heavy metal cation.
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Thermal decomposition of hydronium Jarosite (H3O)Fe3(SO4)2(OH)6
Journal of thermal analysis and calorimetry, 2006Co-Authors: Russ Frost, Ronnie WILLS, Jacob Kloprogge, Wayde N. MartensAbstract:Thermogravimetry combined with mass spectrometry has been used to study the thermal decomposition of a synthetic hydronium Jarosite. Five mass loss steps are observed at 262, 294, 385, 557 and 619C. The mass loss step at 557C is sharp and marks a sharp loss of sulphate as SO 3 from the hydronium Jarosite. Mass spectrometry through evolved gases confirms the first three mass loss steps to dehydroxylation, the fourth to a mass loss of the hydrated proton and a sulphate and the final step to the loss of the remaining sulphate. Changes in the molecular structure of the hydronium Jarosite were followed by infrared emission spectroscopy. This technique allows the infrared spectrum at the elevated temperatures to be obtained. Infrared emission spectroscopy confirms the dehydroxylation has taken place by 400 and the sulphate loss by 650C. Jarosites are a group of minerals formed in evaporite deposits and form a component of the efflorescence. The minerals can function as cation and heavy metal collectors. Hydronium Jarosite has the potential to act as a cation collector by the replacement of the proton with a heavy metal cation.
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THERMAL DECOMPOSITION OF JarositeS OF POTASSIUM, SODIUM AND LEAD
Journal of Thermal Analysis and Calorimetry, 2005Co-Authors: Ray L Frost, Matt L. Weier, Wayde N. MartensAbstract:Jarosites are a group of minerals formed in evaporite deposits and form a component of efflorescence. As such the minerals can function as cation and heavy metal collectors. Thermogravimetry coupled to mass spectrometry has been used to study three Australian Jarosites which are predominantly K, Na and Pb Jarosites. Mass loss steps of K-Jarosite occur over the 130 to 330 and 500 to 622°C temperature range and are attributed to dehydroxylation and desulphation. In contrast the behaviour of the thermal decomposition of Na-Jarosite shows three mass loss steps at 215 to 230, 316 to 352 and 555 to 595°C. The first mass loss step for Na-Jarosite is attributed to deprotonation. For Pb-Jarosite two mass loss steps associated with dehydroxylation are observed at 390 and 418°C and a third mass loss step at 531°C is attributed to the loss of SO3. Thermal analysis is an excellent technique for the study of Jarosites. The analysis depends heavily on the actual composition of the Jarosite.
