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Weiksnar KD, Clavier KA, Robey NM, Townsend TG. Changes in trace metal concentrations throughout the phosphogypsum lifecycle. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 851:158163. [PMID: 35988635 DOI: 10.1016/j.scitotenv.2022.158163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/08/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Phosphogypsum (PG) samples from four distinct sources in the Southeastern US were analyzed to explore the variation in total metal content between newly generated (fresh) PG and PG disposed of in phosphogypsum stacks for different lengths of time (stack). Fresh PG exhibited greater total metal concentrations relative to stack PG, including those identified in the literature as important from a risk assessment perspective (As, Cd, Co, Cr, Cu, Pb, and Zn). The pH varied between fresh and stack PG, with some stack samples exhibiting lower pH than fresh samples, however the relationship between pH and age of sample was not linear. Stack samples with pH values similar to fresh samples possessed lower concentrations of total inorganic metals than fresh samples suggesting that process water drainage and stack location play an important role in the reusability of PG as they can affect the pH of stack PG and total inorganic metal concentrations. Overall observations show that stacking PG for three or more years prior to beneficial reuse provides a construction material with lower total metal concentrations than fresh PG.
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Affiliation(s)
- Kate D Weiksnar
- Department of Environmental Engineering Sciences, University of Florida, P. O. Box 116450, Gainesville, FL 32611-6450, USA
| | - Kyle A Clavier
- Department of Environmental Engineering Sciences, University of Florida, P. O. Box 116450, Gainesville, FL 32611-6450, USA
| | - Nicole M Robey
- Department of Environmental Engineering Sciences, University of Florida, P. O. Box 116450, Gainesville, FL 32611-6450, USA
| | - Timothy G Townsend
- Department of Environmental Engineering Sciences, University of Florida, P. O. Box 116450, Gainesville, FL 32611-6450, USA.
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Zhang B, Chen K, Zhang K, Luo D. Mechanical properties and modification mechanism of phosphogypsum stabilized soil. SN APPLIED SCIENCES 2022. [DOI: 10.1007/s42452-022-05124-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022] Open
Abstract
Abstract
The red clay is widely distributed in Guizhou province, which is characterized by high natural moisture content, difficult compaction and serious shrinkage and crackingin, and phosphogypsum is discharged for 5 million tons every year in Guizhou province. For the sake of effectively reducing the accumulation of phosphogypsum, mixtures were prepared with cement as a curing agent and mass ratios of cement to phosphogypsum of 1:1, 1:2 and 1:3 (low content phosphogypsum group) and phosphogypsum to red clay of 1:1, 1:2 and 1:3 (high content phosphogypsum group). Unconfined compressive strength, expansion, shrinkage and dynamic characteristic tests were conducted to analyze the behavior and mechanical properties of the mixtures. The modification mechanism of the mixtures by phosphogypsum was further explored by XRD (X-ray diffraction) and SEM (scanning electron microscopy). which provided a theoretical basis for the application of phosphogypsum in highway engineering and improved the engineering properties of red clay. The results show that the unconfined compressive strength of the phosphogypsum stabilized soil in the low content phosphogypsum group is greater than that in the high content phosphogypsum group. When cement:phosphogypsum = 1:2.2–1:3, the unconfined compressive strength of the mixture is maximum. When cement:phosphogypsum = 1:3, the maximum dynamic shear modulus of phosphogypsum stabilized soil is the largest. The absolute expansion rate and linear shrinkage rate of phosphogypsum stabilized soil in the low content phosphogypsum group are greater than those in the high content phosphogypsum group. When cement: phosphogypsum = 1:1–1:3, the absolute expansion rate is 6.5–12.3%, and the linear shrinkage rate is 1.3–2%. When red clay:Phosphogypsum = 1:1–1:3, the absolute expansion rate is 0.2–4%, and the linear shrinkage rate is 1–1.5%. The more phosphogypsum content, the smaller the expansion deformation and shrinkage deformation of the mixture. It is suggested that mass ratios of phosphogypsum to red clay is 1:1, and the cement content is 5%. Which can not only make full use of phosphogypsum solid waste, but also improve the engineering properties of red clay.
Article Highlights
The unconfined compressive strength of the phosphogypsum stabilized soil in the low content phosphogypsum group is greater than that in the high content phosphogypsum group. The absolute expansion rate and linear shrinkage rate of phosphogypsum stabilized soil in the low content phosphogypsum group are greater than those in the high content phosphogypsum group.
The strength of phosphogypsum stabilized soil is derived from the comprehensive effect of cement and phosphogypsum. Due to the increment of the phosphogypsum and the decline of proportion of red clay, leading to the decrease in the content of hydrophilic minerals, the expansion deformation and shrinkage deformation characteristics are changed.
Considering strength and deformation characteristics, it is recommended that mixtures with 5% cement content, and phosphogypsum to red clay of 1:1 as subgrade filler, which can not only make full use of phosphogypsum solid waste, but also improve the engineering properties of red clay.
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Lin Y, Sun H, Peng T, Ding W, Li X, Xiao S. A Simple and Efficient Method for Preparing High-Purity α-CaSO4·0.5H2O Whiskers with Phosphogypsum. MATERIALS 2022; 15:ma15114028. [PMID: 35683320 PMCID: PMC9182182 DOI: 10.3390/ma15114028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 05/26/2022] [Accepted: 05/31/2022] [Indexed: 12/04/2022]
Abstract
A simple and efficient approach for the high-purity CaSO4·2H2O (DH) whiskers and α-CaSO4·0.5H2O (α-HH) whiskers derived from such phosphogypsum (PG) was proposed. The impact of different experimental parameters on supersaturated dissolution–recrystallization and preparation processes of α-CaSO4·0.5H2O was elaborated. At 3.5 mol/L HCl concentration, the dissolution temperature and time were 90 °C and 20 min, respectively. After eight cycles and 5–8 times cycles, total crystallization amount of CaSO4·2H2O was 21.75 and 9.97 g/100 mL, respectively, from supersaturated HCl solution. The number of cycles affected the shape and amount of the crystal. Higher HCl concentration facilitated CaSO4·2H2O dissolution and created a much higher supersaturation, which acted as a larger driving force for phase transformation of CaSO4·2H2O to α-CaSO4·0.5H2O. The HCl solution system’s optimum experimental conditions for HH whiskers preparation involved acid leaching of CaSO4·2H2O sample, with HCl concentration 6.0 mol/L, reaction temperature 80 °C, and reaction time 30 min–60 min. Under the third cycle conditions, α-CaSO4·0.5H2O whiskers were uniform in size, clear, and distinct in edges and angles. The length range of α-CaSO4·0.5H2O whiskers was from 106 μm to 231 μm and diameter range from 0.43 μm to 1.35 μm, while the longest diameter ratio was 231. Purity of α-CaSO4·0.5H2O whiskers was approximately 100%, where whiteness reached 98.6%. The reuse of the solution enables the process to discharge no waste liquid. It provides a new reference direction for green production technology of phosphogypsum.
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Affiliation(s)
- Yan Lin
- Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Mianyang 621010, China; (Y.L.); (T.P.); (W.D.); (X.L.); (S.X.)
- Institute of Mineral Materials and Application, Southwest University of Science and Technology, Mianyang 621010, China
| | - Hongjuan Sun
- Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Mianyang 621010, China; (Y.L.); (T.P.); (W.D.); (X.L.); (S.X.)
- Institute of Mineral Materials and Application, Southwest University of Science and Technology, Mianyang 621010, China
- Correspondence:
| | - Tongjiang Peng
- Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Mianyang 621010, China; (Y.L.); (T.P.); (W.D.); (X.L.); (S.X.)
- Institute of Mineral Materials and Application, Southwest University of Science and Technology, Mianyang 621010, China
- Analytical and Testing Center, Southwest University of Science and Technology, Mianyang 621010, China
| | - Wenjin Ding
- Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Mianyang 621010, China; (Y.L.); (T.P.); (W.D.); (X.L.); (S.X.)
- Institute of Mineral Materials and Application, Southwest University of Science and Technology, Mianyang 621010, China
| | - Xiang Li
- Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Mianyang 621010, China; (Y.L.); (T.P.); (W.D.); (X.L.); (S.X.)
- Institute of Mineral Materials and Application, Southwest University of Science and Technology, Mianyang 621010, China
| | - Sha Xiao
- Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Mianyang 621010, China; (Y.L.); (T.P.); (W.D.); (X.L.); (S.X.)
- Institute of Mineral Materials and Application, Southwest University of Science and Technology, Mianyang 621010, China
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Alla M, Harrou A, Elhafiany ML, Azerkane D, El Ouahabi M, Gharibi EK. Reduction of phosphogypsum to calcium sulfide (CaS) using metallic iron in a hydrochloric acid medium. PHOSPHORUS SULFUR 2022. [DOI: 10.1080/10426507.2022.2052881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Majda Alla
- Laboratory of Electrical Engineering and maintenance, Higher School of Technology, Mohammed First University, Oujda, Morocco
| | - Achraf Harrou
- Laboratory of Applied Chemistry and Environment Team of Mineral Solid Chemistry, Faculty of Sciences, Mohammed First University, Oujda, Morocco
| | - Mohammed Lamine Elhafiany
- Laboratory of Electrical Engineering and maintenance, Higher School of Technology, Mohammed First University, Oujda, Morocco
| | - Dounia Azerkane
- Laboratory of Applied Chemistry and Environment Team of Mineral Solid Chemistry, Faculty of Sciences, Mohammed First University, Oujda, Morocco
| | - Meriam El Ouahabi
- UR Argile, Géochimie et Environnement sédimentaires (AGEs), Département de Géologie, University of Liège, Liège, Belgium
| | - El Khadir Gharibi
- Laboratory of Applied Chemistry and Environment Team of Mineral Solid Chemistry, Faculty of Sciences, Mohammed First University, Oujda, Morocco
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Chen H, Lu Y, Zhang C, Min F, Huo Z. Red Yeast Improves the Potential Safe Utilization of Solid Waste (Phosphogypsum and Titanogypsum) Through Bioleaching. Front Bioeng Biotechnol 2022; 9:777957. [PMID: 35036400 PMCID: PMC8758580 DOI: 10.3389/fbioe.2021.777957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 12/07/2021] [Indexed: 11/30/2022] Open
Abstract
Phosphogypsum (PG) and titanium gypsum (TG), as a by-product (solid waste) in phosphate fertilizer and titanium dioxide industry, are causing serious environmental hazards. The resource/harmless application of PG and TG is the development trend in the future. The biological function of red yeast (Rho: Rhodotorula mucilaginosa) can effectively reduce the concentration of pollutants in the environment and has the potential of biological flotation/purification of mineral solid waste. In this study, the bioremediation mechanism and safe utilization efficiency of Rho for different contents of PG and TG were explored by using its biological flotation function. The X-ray fluorescence spectrometry (XRF) results showed that F was the main toxic element in PG and TG, and Pb and Cd did not reach the detection limit. The processing capacity of Rho for PG (>10 g/ml) is higher than that of TG (<5 g/ml). After bioleaching by Rho, the proportion of F in PG and TG solid decreased by 61.45–63.79% and 49.45–59.19%, respectively. The results of three-dimensional fluorescence, extracellular polymeric substance (EPS) extraction, X-ray diffraction (XRD), and scanning electron microscopy (SEM) confirmed that Rho could accelerate the release of harmful elements (F) in PG and TG. SEM showed that Rho cells and secretions adhered and wrapped on PG/TG, causing PG/TG decomposition and fragmentation. In addition, the adsorption of EPS and the formation of Ca5(PO4)3F are two main ways for Rho to remove F. Furthermore, under the condition of high concentration bioleaching, Rho can accelerate the release and utilization of P in PG, which is not only for the re-precipitation of Ca5(PO4)3F but also conducive to the reproduction and utilization of microorganisms. Meanwhile, the purification/safe reuse of PG by Rho is easier than that of TG. Therefore, the toxicity of PG and TG bioleaching by Rho can be greatly reduced, suggesting the huge potential of Rho in soil improvement and remediation.
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Affiliation(s)
- Haoming Chen
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, China
| | - Yuqi Lu
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, China
| | - Chaonan Zhang
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, China
| | - Fangfang Min
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, China
| | - Zongli Huo
- Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China
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Mas JL, Ramírez JRC, Bermúdez SH, Fernández CL. ASSESSMENT OF NATURAL RADIOACTIVITY LEVELS AND RADIATION EXPOSURE IN NEW BUILDING MATERIALS IN SPAIN. RADIATION PROTECTION DOSIMETRY 2021; 194:178-185. [PMID: 34218283 PMCID: PMC8280263 DOI: 10.1093/rpd/ncab089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 03/02/2021] [Accepted: 05/25/2021] [Indexed: 05/14/2023]
Abstract
Novel building materials were manufactured and analyzed for 226Ra, 232Th and 40K using an HPGe gamma-ray spectrometer. The results show that the highest value of 40K was 4530 Bq per kg which was measured in a sample containing fly ashes from olive stones. The highest values of 226Ra and 232Th activities were 181 and 185 Bq per kg, which were measured in a sample with fly ashes from the co-combustion of coal and coke, respectively. On the other hand, the lowest values of 40K, 226Ra and 232Th activities were obtained for samples incorporating mussel shells. The radiological health hazard parameters, such as radium equivalent activity (Raeq), activity concentration index (I), absorbed and effective dose rates, associated with these radionuclides were evaluated. These values are within the EU recommended limits in building materials, except for samples of concrete containing fly ashes from olive stones, coal and coke. This study has contributed to the inclusion of industrial wastes that have not been collected previously in the Naturally Occurring Radioactive Material (NORM) databases on radioactivity of building materials.
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Affiliation(s)
| | - J R Caro Ramírez
- Mina Cobre Las Cruces, carretera SE-3410, km 4100.41860 Gerena, Sevilla, Spain
| | - S Hurtado Bermúdez
- Dpto. Física Aplicada II, ETSA, Universidad de Sevilla, Avda. Reina Mercedes 2, Sevilla 41012, Spain
| | - C Leiva Fernández
- Dpto. Ingeniería Química y Ambiental, ETS-Ingeniería, Univ. Sevilla, C/de los Descubrimientos, s/n, Pabellón Plaza de América, Sevilla 41092, Spain
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Characterization and Analysis of the Carbonation Process of a Lime Mortar Obtained from Phosphogypsum Waste. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18126664. [PMID: 34205707 PMCID: PMC8296396 DOI: 10.3390/ijerph18126664] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/17/2021] [Accepted: 06/19/2021] [Indexed: 11/23/2022]
Abstract
This work addresses the reuse of waste products as a raw material for lime putties, which are one of the components of mortar. 1:3 Lime/sand mortars very similar to conventional construction mortars were prepared using a lime putty obtained from the treatment of phosphogypsum with sodium hydroxide. The physical, rheological and mechanical properties of this phosphogypsum-derived mortar have been studied, as well as the mineralogical composition, microstructure by scanning electron microscope (SEM) and curing process by monitoring carbonation and ultrasonic propagation velocity. Considering the negative influence of sulphates on the hardened material, the behaviour of the material after sulphates precipitation by adding barium sulphate was additionally tested. Carbonation progressed from the outside to the inside of the specimen through the porous system by Liesegang rings patterns for mortars with soluble sulphates, while the carbonation with precipitated sulphates was controlled by diffusion-precipitation. Overall, the negative influence of low-sulphate contents on the mechanical properties of mortars was verified. It must be highlighted the importance of their precipitation to obtain adequate performance.
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Phosphogypsum and Black Steel Slag as Additives for Ecological Bentonite-Based Materials: Microstructure and Characterization. MINERALS 2020. [DOI: 10.3390/min10121067] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The Black Steel slag (Ss) and phosphogypsum (PG) are industrial wastes produced in Morocco. In order to reduce these two wastes and to evaluate their pozzolanic reactivity in the presence of water, they were incorporated into bentonite (B) mixed with lime (L). The studied mixtures (BLW, BL–PG–W and BL–PG–Ss–W) were analyzed by X-ray diffraction, Infrared spectroscopy, Raman spectroscopy and SEM/EDX analysis. Compressive strength tests were performed on hardened specimens. The results obtained show that the hydration kinetics of the B–L–W and B–L–PG–W mixtures are slow. The addition of PG to a bentonite––lime mixture induces the formation of new microstructures such as hydrated calcium silicate (C–S–H) and ettringite, which increases the compressive strength of the cementitious specimens. The addition of the Ss to a mixture composed of 8%PG and 8%L–B accelerates the kinetics of hydration and activates the pozzolanic reaction. The presence of C2S in the slag helps to increase the mechanical strength of the mixture B–L–PG–Ss. The compressive strength of the mixtures BL–W, BL–PG–W and BL–PG–Ss–W increases from 15 to 28 days of setting. After 28 days of setting, 8% of Sc added to the mixture 8% PG–8%L–B is responsible for an increase of the compressive strength to 0.6 MPa.
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