title: Mechanistic and Kinetic Analysis of Na2SO4-Modified Laterite Decomposition by Thermogravimetry Coupled with Mass Spectrometry.
abstract: Nickel laterites cannot be effectively used in physical methods because of their poor crystallinity and fine grain size. Na2SO4 is the most efficient additive for grade enrichment and Ni recovery. However, how Na2SO4 affects the selective reduction of laterite ores has not been clearly investigated. This study investigated the decomposition of laterite with and without the addition of Na2SO4 in an argon atmosphere using thermogravimetry coupled with mass spectrometry (TG-MS). Approximately 25 mg of samples with 20 wt% Na2SO4 was pyrolyzed under a 100 ml/min Ar flow at a heating rate of 10°C/min from room temperature to 1300°C. The kinetic study was based on derivative thermogravimetric (DTG) curves. The evolution of the pyrolysis gas composition was detected by mass spectrometry, and the decomposition products were analyzed by X-ray diffraction (XRD). The decomposition behavior of laterite with the addition of Na2SO4 was similar to that of pure laterite below 800°C during the first three stages. However, in the fourth stage, the dolomite decomposed at 897°C, which is approximately 200°C lower than the decomposition of pure laterite. In the last stage, the laterite decomposed and emitted SO2 in the presence of Na2SO4 with an activation energy of 91.37 kJ/mol. The decomposition of laterite with and without the addition of Na2SO4 can be described by one first-order reaction. Moreover, the use of Na2SO4 as the modification agent can reduce the activation energy of laterite decomposition; thus, the reaction rate can be accelerated, and the reaction temperature can be markedly reduced.
authors.affiliation: Key Laboratory for Coal Science and Technology of Ministry of Education and Shanxi Province, Institute for Chemical Engineering of Coal, Taiyuan University of Technology, Taiyuan 030024, China.
authors.forename: Song
authors.initials: S
authors.lastname: Yang
authors.affiliation: Key Laboratory for Coal Science and Technology of Ministry of Education and Shanxi Province, Institute for Chemical Engineering of Coal, Taiyuan University of Technology, Taiyuan 030024, China.
authors.forename: Wenguang
authors.initials: W
authors.lastname: Du
authors.affiliation: Key Laboratory for Coal Science and Technology of Ministry of Education and Shanxi Province, Institute for Chemical Engineering of Coal, Taiyuan University of Technology, Taiyuan 030024, China.
authors.forename: Pengzheng
authors.initials: P
authors.lastname: Shi
authors.affiliation: Key Laboratory for Coal Science and Technology of Ministry of Education and Shanxi Province, Institute for Chemical Engineering of Coal, Taiyuan University of Technology, Taiyuan 030024, China.
authors.forename: Ju
authors.initials: J
authors.lastname: Shangguan
authors.affiliation: College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
authors.forename: Shoujun
authors.initials: S
authors.lastname: Liu
authors.affiliation: College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
authors.forename: Changhai
authors.initials: C
authors.lastname: Zhou
authors.affiliation: College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Chen
authors.affiliation: Key Laboratory for Coal Science and Technology of Ministry of Education and Shanxi Province, Institute for Chemical Engineering of Coal, Taiyuan University of Technology, Taiyuan 030024, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Coal Science and Technology of Ministry of Education and Shanxi Province, Institute for Chemical Engineering of Coal, Taiyuan University of Technology, Taiyuan 030024, China.
authors.forename: Huiling
authors.initials: H
authors.lastname: Fan
mesh_terms: D007700:Kinetics; D013058:Mass Spectrometry / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*; D013696:Temperature; D013818:Thermogravimetry / Q000379:methods*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D008903:Minerals; D013431:Sulfates; D014867:Water; C012036:sodium sulfate; D009532:Nickel