Purification of Sulfur Waste Under Hydrothermal Conditions
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Purification of Sulfur Waste Under Hydrothermal Conditions Gabriele Sarapajevaite1 · Kestutis Baltakys1 Received: 24 April 2020 / Accepted: 13 August 2020 © Springer Nature B.V. 2020
Abstract Large scale of sulfuric acid production leads to huge amount of solid state industrial waste, which is stored in landfill sites and may cause many environmental problems. The purpose of this study is to characterize the sulfur waste and to determine the optimal conditions of sulfur regeneration from waste under hydrothermal conditions.Therefore the recovery of elemental sulfur from waste (waste product of sulfuric acid production) was investigated. Samples were examined by simultaneous thermal analysis (STA), X-ray diffraction analysis (XRD) and X-ray fluorescence spectroscopy (XRF). It was determined that the used material mainly consisted of sulfur (86.3%), calcium (6.9%), iron (4%) and silicon (2.3%). The primary methods and conditions of waste preparation for further treatment were determined. It was established that sulfur and impurities (e.g. quartz, calcium compounds) can be separated by applying rapid cooling procedure after hydrothermal treatment. Most efficient conditions of sulfur waste purification were determined and the maximum obtained yield of purification was 97.35%. Graphic abstract
Keywords Sulfur waste · Hydrothermal treatment · Purification
Statement of Novelty This article presents the information on solid industrial waste characterization and provides fundamental research data on elemental sulfur extraction during hydrothermal sulfur waste treatment. The hydrothermal technique joined with * Gabriele Sarapajevaite [email protected] 1
Department of Silicate Technology, Kaunas University of Technology, Radvilenu Road 19, 50254 Kaunas, Lithuania
rapid cooling approach which was applied in this research has not been published or described before in the area of industrial waste recycling.
Introduction Sulfuric acid is one of the most consumed chemical reagents in the world—270 million tons were produced in 2018 alone [1]. The majority (61%) of all sulfuric acid is produced from elemental sulfur [2]. However, this type of production
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Waste and Biomass Valorization
Methods and Materials Raw Materials In this work the sulfur waste used, i.e., the waste product of sulfuric acid production, was from sulfur raw material in the chemical plant “Lifosa” (Kedainiai, Lithuania). The origin of sulfur raw material was petroleum gas. The sulfur content in raw material is no less than 99.98 wt%, the content of ashes is no more than 0.02 wt% and the content of organic material is no more than 0.01 wt%. The content of water in raw material is no more than 0.02% wt. and no mechanical impurities are possible. Sulfur waste was collected during the filtration of melted elemental sulfur. In order to determine the chemical and mineralogical composition, dry material was milled for 5 min at 950 rpm in a vibrating cup ‘‘Pulverisette 9’’ mill. X-ray diffraction (X
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