scholarly journals Phosphogypsum Conversion into Calcium Fluoride and Sodium Sulfate

2020 ◽  
Vol 44 (6) ◽  
pp. 407-412
Author(s):  
Yassine Ennaciri ◽  
Mohammed Bettach ◽  
Hanan El Alaoui-Belghiti
Keyword(s):  
Phosphoric Acid ◽  
Glass Industry ◽  
Calcium Fluoride ◽  
Sodium Sulfate ◽  
Acid Production ◽  
Room Temperature ◽  
Metallurgical Industry ◽  
Environmental Problems ◽  
The World ◽  
Phosphogypsum Waste

The phosphoric acid production in the world generates a large amount of phosphogypsum beside the emission of toxic acid fluorine gas into the atmosphere, which can cause a several environmental problems. To remedying these problems, an environmental procedure permit recycling phosphogypsum waste by NaF into valuable products, was presented in this work. According the obtained results, the proposed process is feasible and leads preparing a relatively pure CaF2 and Na2SO4. This last is recommended in detergent and glass industry, while the resulting CaF2 can be utilized in metallurgical industry. The optimum conversion conditions were achieved with the exact stoichiometric phosphogypsum and NaF at reaction duration of 90 minutes under room temperature.

Rare Earth Elements Recovery and Sulphate Removal from Phosphogypsum Waste Waters with Sulphate Reducing Bacteria

2017 ◽  
Vol 262 ◽  
pp. 573-576 ◽  
Author(s):  
Jarno Mäkinen ◽  
Malin Bomberg ◽  
Marja Salo ◽  
Mona Arnold ◽  
Pertti Koukkari
Keyword(s):  
Rare Earth ◽  
Phosphoric Acid ◽  
Rare Earth Elements ◽  
Acid Production ◽  
Sulphate Reduction ◽  
Anaerobic Sludge ◽  
Seepage Water ◽  
Sulphate Reducing Bacteria ◽  
Reducing Bacteria ◽  
Phosphogypsum Waste

Phosphogypsum waste, originating from phosphoric acid production from apatite ores, is well known for its high production rate and possible release of sulphate-rich seepage waters. In addition to negative environmental impacts, phosphogypsum waste heaps are also remarkable secondary sources of Rare Earth Elements (REE); in the phosphoric acid production process a majority of REE, occurring in apatite, are precipitated to the phosphogypsum waste. Therefore, a method treating both sulphate-rich waters and recovering REE from phosphogypsum heaps and seepage waters would offer both economic and environmental benefits. In this ongoing study, seepage waters from a phosphogypsum heap are treated with Sulphate Reducing Bacteria (SRB) and ethanol as a substrate. Sulphate is first reduced to hydrogen sulphide, which then precipitates REE as sulphides. The main challenge, low concentration of REE in seepage waters (e.g. 2.87 μg/l La, 5.13 μg/l Ce, 0.67 μg/l Y and 3.32 μg/l Nd), is overcome by utilizing continuous mode, semi-passive and cost effective column apparatus, requiring no agitation and performing both sulphate reduction and REE recovery in a single reactor. The SRB method results in a sulphate reduction rate of 40-80 % (from app. 1400 mg/l to 276-844 mg/l sulphate in the effluent) and efficient REE recovery from seepage water. The concentrate obtained from the column consists of a mixture of anaerobic sludge and precipitated REE, with respective REE concentrations of 202 mg/kg La, 477 mg/kg Ce, 49 mg/kg Y and 295 mg/kg Nd.

scholarly journals HIGH-TEMPERATURE DECONTAMINATION AND UTILIZATION OF PHOSPHOGYPSUM

2004 ◽  
Vol 12 (4) ◽  
pp. 138-145
Author(s):  
Algimantas Kazragis
Keyword(s):  
High Temperature ◽  
Phosphoric Acid ◽  
Central Region ◽  
Acid Production ◽  
Environmental Problems ◽  
Raw Material ◽  
Toxic Pollutants ◽  
The City ◽  
Hemi Hydrate ◽  
Full Operation

Waste piles of phosphogypsum formed from deposits of phosphoric acid production by‐product loom near the city of Kedainiai in the center of Lithuania. Every year about 250 thousand tons of this by‐product were gathered when the plant was in full operation. At present, about 13 to 15 million tons of phosphogypsum have accumulated which is mainly gypsum dihydrate – (95–98) %, however, contaminated with phosphoric and fluoric acids as well as with other hazardous admixtures what makes this raw material ecologically harmful and also hampers the use of phosphogypsum instead of natural gypsum for the production of binding materials. These materials pollute the environment. Phosphogypsum can be “deacidified” with lime and then treated as normal natural gypsum to obtain hemi hydrate gypsum. However, good‐quality binding materials were not obtained in this case. Heating of phosphogypsum up to a temperature of 600 °C provides for the decomposition and elimination of binding obstruction admixtures. Heating to 1000 °C and higher temperatures causes the decomposition of the former with the formation of an activator in anhydrite lime and thus anhydrite cement. In general, the utilization of this environmentally harmful waste and the binding of toxic pollutants can contribute to the solution of environmental problems in the central region of Lithuania.

Overview of Current Phosphoric Acid Production Processes and a New Idea of Kiln Method

2020 ◽  
Vol 17 ◽  
Author(s):  
Guangya Zheng ◽  
Jupei Xia ◽  
Zhengjie Chen
Keyword(s):  
Phosphoric Acid ◽  
Acid Production ◽  
Phosphate Rock ◽  
Low Grade ◽  
Production Methods ◽  
Production Processes ◽  
Major Equipment ◽  
Development Prospects ◽  
Great Competitiveness

: China primarily contains medium and low-grade phosphorus ores that are used to produce phosphoric acid. Here, we provide an overview of phosphoric acid production processes, including wet, thermal, and kiln methods, as well as the fundamental principles, major equipment, and technological aspects of each process. Progress in the kiln method using lowgrade phosphate rock is described, which involves the KPA and CDK processes. The literature shows that the addition of admixtures adds great competitiveness to kiln phosphate production methods and has considerable development prospects.

scholarly journals Handrails through the Swamp? A Pilot to Test the Integration and Implementation Science Framework in Complex Real-World Research

2021 ◽  
Vol 13 (10) ◽  
pp. 5491
Author(s):  
Melissa Robson-Williams ◽  
Bruce Small ◽  
Roger Robson-Williams ◽  
Nick Kirk
Keyword(s):  
Pilot Study ◽  
Case Studies ◽  
Implementation Science ◽  
Real World ◽  
Environmental Problems ◽  
Environmental Research ◽  
Integrative Framework ◽  
The World ◽  
Science Framework ◽  
Real World Problems

The socio-environmental challenges the world faces are ‘swamps’: situations that are messy, complex, and uncertain. The aim of this paper is to help disciplinary scientists navigate these swamps. To achieve this, the paper evaluates an integrative framework designed for researching complex real-world problems, the Integration and Implementation Science (i2S) framework. As a pilot study, we examine seven inter and transdisciplinary agri-environmental case studies against the concepts presented in the i2S framework, and we hypothesise that considering concepts in the i2S framework during the planning and delivery of agri-environmental research will increase the usefulness of the research for next users. We found that for the types of complex, real-world research done in the case studies, increasing attention to the i2S dimensions correlated with increased usefulness for the end users. We conclude that using the i2S framework could provide handrails for researchers, to help them navigate the swamps when engaging with the complexity of socio-environmental problems.

scholarly journals Increasing University Competitiveness through Assessment of Green Content in Curriculum and Eco-Labeling in Higher Education

2021 ◽  
Vol 13 (2) ◽  
pp. 712
Author(s):  
Andrea Okanović ◽  
Jelena Ješić ◽  
Vladimir Đaković ◽  
Simonida Vukadinović ◽  
Andrea Andrejević Panić
Keyword(s):  
Higher Education ◽  
Sustainable Development ◽  
Comparative Analysis ◽  
Environmental Problems ◽  
Green Jobs ◽  
Positive Effects ◽  
The World ◽  
Different Types ◽  
Novi Sad ◽  
The University

Growing environmental problems and increasing requirements of green jobs force universities around the world not only to transform their curricula but also to enrich existing ones with contents related to the promotion of sustainable development. This paper aims to show the importance of measuring and monitoring the share of green contents in all university activities, as only in that way it is possible to monitor trends and give realistic assessments of their effect and importance. The paper presents a comparative analysis of different types of methodologies for assessing sustainable activities at universities as well as research conducted at the University of Novi Sad in Serbia and its comparison with the University of Gothenburg (Sweden). This research aims to point out the importance of increasing competitiveness in higher education through assessment of green content in a curriculum and its promotion. In this way, through eco-labeling methodology, it would be easier to identify those contents that, in a certain share, contribute to the promotion of sustainable development. Furthermore, this methodology can easily be extended across the country and the region, which would bring positive effects to all stakeholders in higher education.

Water–Phosphorus Nexus for Wet-Process Phosphoric Acid Production

2018 ◽  
Vol 57 (20) ◽  
pp. 6968-6979
Author(s):  
Hang Ma ◽  
Xiao Feng ◽  
Chun Deng
Keyword(s):  
Phosphoric Acid ◽  
Acid Production ◽  
Wet Process

“Nature” and the (Built) Environment

2016 ◽  
Author(s):  
Steven Vogel
Keyword(s):  
Built Environment ◽  
Environmental Problems ◽  
The World ◽  
Human Practices

Environmentalismshould deal with theenvironment, meaning that which environs us; instead it too frequently deals with “nature.” If the latter term means that part of the world that humans haven’t transformed, the trouble is that naturedoesn’tenviron us: in the Anthropocene, we’re surrounded by an environment that humans have built. An environmentalism of the built environment would worry about why we’ve built it so badly, and would focus on the phenomenon of “reification,” whereby the actual practices of humans in constructing their world are hidden and the things and institutions surrounding us come to seem like “facts of nature.” Environmental problems are not problems about nature: they are social and political problems about how human practices ought to be organized and about the norms by which those practices ought to be guided.

scholarly journals Process Technology for Phosphoric Acid Production in Saudi Arabia

1992 ◽  
Vol 4 (2) ◽  
pp. 239-254
Author(s):  
Tariq F. Al-Fariss ◽  
H.Ö. Özbelge ◽  
H.S.H. El-Shall
Keyword(s):  
Saudi Arabia ◽  
Phosphoric Acid ◽  
Acid Production ◽  
Process Technology

scholarly journals Legal regulation of solving problems of pollution prevention Oceans

2020 ◽  
Author(s):  
S.V. Strygina
Keyword(s):  
Social Responsibility ◽  
International Cooperation ◽  
Marine Environment ◽  
Pollution Prevention ◽  
Environmental Problems ◽  
Legal Regulation ◽  
Legal Basis ◽  
National Legislation ◽  
The World

The article analyses the legal basis of activities of cleaning up the world oceans. It is emphasized that they are complex. The role of the UN in solving environmental problems is also highlighted. The need for international cooperation in the protection of the marine environment is mentioned. The article raises the problem of improving both international and national legislation and eliminating gaps in the law. The importance of social responsibility of business is emphasized.

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