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.

scholarly journals Researches Regarding a Protein Hydrolysate Used as Adjuvant in Fertilization Process

2019 ◽  
Vol 76 (2) ◽  
pp. 78
Author(s):  
Elena Mihaela NAGY ◽  
Constantin COȚA ◽  
Nicolae CIOICA ◽  
Zoltan GYORGY ◽  
Lucian FECHETE-TUTUNARU ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
High Temperature ◽  
Phosphoric Acid ◽  
Alkaline Hydrolysis ◽  
Potassium Hydroxide ◽  
Protein Hydrolysate ◽  
Raw Material ◽  
Urea Content ◽  
High Temperature And Pressure ◽  
Temperature And Pressure

Within the paper the results of conducted researches in order to obtain a protein hydrolysate from wool waste as raw material are presented. The experiments were conducted in two variants: a) alkaline hydrolyse using potassium hydroxide, a mix of potassium hydroxide with urea and a mix of potassium hydroxide with sodium hydroxide as well as b) acidic hydrolyse with sulfuric acid or a mix of sufuric acid with phosphoric acid in different proportions. The parameters intervals used were: pH 0,5-2,5 for acidic hydrolyse and pH 9,5-13,5 for the alkalinic one; temperatures between 120-150 °C and pressures between 1,4-4,6 bar. Acid hydrolysis is favored by the high proportion of sulfuric acid, phosphoric acid, a low pH and from high temperature and pressure. The alkaline hydrolysis is favored by a pH higher then 12 as well as the urea content. A high temperature and pressure has a beneficial effect over alkaline hydrolysis.

scholarly journals Evaluating radiation risks and resource opportunities associated with phosphogypsum in the Philippines

2021 ◽  
Author(s):  
Reymar R. Diwa ◽  
Estrellita U. Tabora ◽  
Botvinnik L. Palattao ◽  
Nils H. Haneklaus ◽  
Edmundo P. Vargas ◽  
...  
Keyword(s):  
Phosphoric Acid ◽  
Rare Earths ◽  
Acid Production ◽  
The Philippines ◽  
Raw Material ◽  
Surface Samples ◽  
Radiometric Survey ◽  
Activity Concentrations ◽  
Secondary Raw Material

AbstractPhosphogypsum (PG) accumulates during wet-phosphoric acid production for fertilizers. In the Philippines, PG is partly (40%) utilized to produce gypsum walls and cement. This work assesses the radiological risks and resource opportunities associated with PG stacks in the Philippines. The conducted in situ radiometric survey measured the activity concentrations of 40K, 238U, and 232Th at 270 locations. Besides, another 120 surface samples were collected. Pure PG exceeds the recommended radiation limits, but simple dilution with conventional materials can make PG available as an inexpensive secondary raw material for construction. PG further contains relevant concentrations of rare earths and Y (195 ppm).

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.

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 Temperature, Disease, and Death in London: Analyzing Weekly Data for the Century from 1866 to 1965

2021 ◽  
pp. 1-41
Author(s):  
W. Walker Hanlon ◽  
Casper Worm Hansen ◽  
Jake Kantor
Keyword(s):  
Nineteenth Century ◽  
High Temperature ◽  
Mortality Data ◽  
Late Nineteenth Century ◽  
Infant Deaths ◽  
Digestive Diseases ◽  
Late Nineteenth ◽  
The Impact ◽  
The City

Using novel weekly mortality data for London spanning 1866-1965, we analyze the changing relationship between temperature and mortality as the city developed. Our main results show that warm weeks led to elevated mortality in the late nineteenth century, mainly due to infant deaths from digestive diseases. However, this pattern largely disappeared after WWI as infant digestive diseases became less prevalent. The resulting change in the temperature-mortality relationship meant that thousands of heat-related deaths—equal to 0.9-1.4 percent of all deaths— were averted. These findings show that improving the disease environment can dramatically alter the impact of high temperature on mortality.

Experimental Study on Carbonization of Low-Rank Pulverized Coal with High Temperature Heat Pipe

2014 ◽  
Vol 953-954 ◽  
pp. 1035-1039
Author(s):  
Li Qun Wang ◽  
Zhong Bo Yi ◽  
Zhong Xiang Wei
Keyword(s):  
High Temperature ◽  
Heat Pipe ◽  
Pulverized Coal ◽  
Holding Time ◽  
Raw Material ◽  
Low Rank ◽  
Experimental Result ◽  
Operating Characteristics ◽  
Temperature Heat ◽  
High Temperature Heat Pipe

Aimed at improving the utilization of pulverized coal, high-temperature heat pipe technology was introduced into lignite carbonization.Under the design of power of 10kw semi-industrial pulverized coal carbonization test equipment, Fugu lignite coal as raw material to investigate the operating characteristics of the device and carbonization characteristics. Experimental result shows that the high temperature heat pipes heat steadily and meet the temperature requirement of low-temperature carbonization. With the extension of the holding time, the semi-coke fixed carbon content increasing, but volatile matter vice versa, however, holding time above 60 minutes, the effect of carbonization is not obvious, and the best carbonization time is 30 ~ 60 minutes. The length of the holding time has little effect on gas composition, the content of H2 and CH4 are relatively higher than the rest gas, (H2 + CH4) gas accounted for 70% of the total, the heating value remains at 18.76 ~ 19.22MJ/m3, belongs to medium-high value gas, could provide for industrial and civilian use.

Macromolecular covalently cross-linked quaternary ammonium poly(ether ether ketone) with polybenzimidazole for anhydrous high temperature proton exchange membranes

2014 ◽  
Vol 5 (17) ◽  
pp. 4939-4947 ◽  
Author(s):  
Na Zhang ◽  
Chengji Zhao ◽  
Wenjia Ma ◽  
Shuang Wang ◽  
Baolong Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Phosphoric Acid ◽  
Quaternary Ammonium ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Ether Ether Ketone ◽  
Poly Ether Ether Ketone ◽  
Ether Ketone ◽  
Improved Performance

The phosphoric acid doped quaternary ammonium poly(ether ether ketone) membranes cross-linked with PBI showed improved performance.

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

scholarly journals Preparation of Graphene/TiO2Composite Nanomaterials and Its Photocatalytic Performance for the Degradation of 2,4-Dichlorophenoxyacetic Acid

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Donggen Huang ◽  
Tianzi Yang ◽  
Zhuanghong Mo ◽  
Qin Guo ◽  
Shuiqing Quan ◽  
...  
Keyword(s):  
High Temperature ◽  
Sol Gel ◽  
Chemical Properties ◽  
Hydrogen Atmosphere ◽  
Raw Material ◽  
Dichlorophenoxyacetic Acid ◽  
Anoxic Water ◽  
Field Environment ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Electrochemical Stripping

The graphene (GR) was prepared by an improved electrochemical stripping method using a high-purity graphite rod as raw material and high temperature heat reduction in hydrogen atmosphere, and the graphene/TiO2(GR/TiO2) composite nanomaterials were manufactured by the method of sol-gel and high temperature crystallization in hydrogen atmosphere using butyl titanate and electrolysis graphene as precursors. The physical and chemical properties of the composites had been characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer (UV-Vis), scanning electron microscopy (SEM), Transmission Electron Microscope (TEM),  and specific surface area (SSA) by BET method. The photocatalytic properties of GR/TiO2composites nanomaterials in anoxic water were studied by using 2,4-dichlorophenoxyacetic acid (2,4-D) as probe. The results showed that graphite was well intercalated and peeled by a facile electrolysis method in different electric field environment; a well dispersed and rings structure of graphene was prepared by coupling ultrasound-assisted changing voltage electrochemical stripping technology. The as-prepared GR/TiO2composites had good performance for the photocatalytic degradation of 2,4-D in anoxic water; the chlorines were removed from benzene ring; the middle products of dichlorophenol, chlorophenol, phloroglucinol, and so forth were produced from the photocatalytic redox reaction of 2,4-D in anoxic water; parts of 2,4-D were decomposed completely, and CO2and H2O were produced.

Sign in / Sign up

Export Citation Format

Share Document