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·Phosphogypsum PG the main industrial by product of phosphate fertilizer industry primarily consists of calcium sulfate dihydrate However it contains various impurities with variable quantities depending on the origin of the phosphate rock These impurities can restrict the reuse of phosphogypsum as a secondary primary resource
·Abstract To fully utilize and recycle the waste phosphogypsum the apparent solid solid reaction between CaS and CaSO4 has been widely applied in the production of sulfuric acid and cement However to prevent discontinuous and unstable production caused by the blockage of the reactor in the reaction it is very important to raise the ash fusion points of
4 ·Given the excessive presence of phosphogypsum with an original deeper coloration [81] in the core PCBAs it is hypothesized that these dark bands represent internal substances migration out and contaminating the matrix accompanying the release of the internal curing water [55] Nonetheless these images present differences in the width of the
·The concentrations of 238U 226Ra 232Th and 40K maintained in phosphate rock PR phosphoric acid PA and phosphogypsum PG samples and its possible radiation hazards have been measured The radionuclides in phosphate rock have been redistributed unsymmetrically between phosphoric acid and phosphogypsum during the production process
·In this paper the hazard prevention and safety risk assessment control model of PG comprehensive utilization is scientifically established from three aspects hazard identification risk analysis and hazard characterization as shown in Fig 12 Firstly the site environment and pollutants are investigated to determine the types distribution
·Two samples collected from the phosphogypsum deposits of the chemical products industry Elixir Prahovo Serbia were subjected to a recrystallization experiment performed over several repeated cycles
·A lesser storm Hurricane Frances which hit the state s eastern coast as a Category 2 and churned across central Florida in 2004 sent 65 million gallons of acidic wastewater from phosphogypsum
·Phosphogypsum is a solid waste byproduct from processing phosphate ore to make phosphoric acid that is later used in fertilizer The phosphate ore and the resulting phosphogypsum contain radium which decays to form radon gas However exposure to radon at higher levels and over prolonged periods of time can pose a serious hazard to human
·Radiological hazard indices such as the radium equivalent activity Raeq the gamma index I γ alpha index I α the absorbed gamma dose rate D in and the corresponding annual effective
·internal wallspilt wall 4170、 6、 67、 63、 96、 10 1 ： ICEM
Phosphogypsum is classified into naturally occurring radioactive materials containing radionuclides such as ²³⁸ U ²²⁶ Ra and ²³² Th and heavy metals which are dispersed in different
·and sulfuric acids in the phosphogypsum are an obstacle to its use in the production of building materials The effect of an acidic environment on phosphogypsum was studied using Na2CO3 K2CO3 and NH4 2CO3 salts Special regimes for washing the initial phosphogypsum were developed in which the reactivity increased by times due to
·Phosphogypsum PG is a by product produced during the wet process of phosphoric acid H3PO4 production from natural phosphate rocks Approximately 4 6 tons of PG is produced per ton of
• Phosphogypsum produced in North Florida contains roughly 5 10 picocuries per gram pCi/g of radium while phosphogypsum from Central Florida contains about 20 35 pCi/g radium • The EPA prohibits the use of phosphogypsum An exception is made for phosphogypsum with an average concentration less than 10 pCi/g radium which can
·In this paper fly ash and coal gangue as the main raw materials potassium feldspar albite as the composite flux phosphogypsum as the bonding agent the semi melting method was used to prepare fly ash coal gangue phosphogypsum based wall
·Recent studies have focused on a particular method for heavy metal ions removal such as electrocoagulation EC adsorption using synthetic and natural adsorbents magnetic field implementation
·The surface stockpiling of phosphogypsum not only occupies a large amount of land but also seriously harms the surrounding ecological environment The preparation of phosphogypsum into filling materials for mine filling can not only maintain the stability of surrounding rock reduce surface subsidence enhance the recovery of resources but it can
·Phosphogypsum PG is reused as aggregate in the cemented backfill which effectively improves the PG reutilization efficiency However the massive impurities contained in aggregate PG would
·Consecutive pozzolanic layerings to depress internal sulfate attack corrosion of OPC by phosphogypsum based cold bonded aggregates Author links open overlay panel Gaoshang Ouyang a c Tao Sun b c d [16] that corresponds to preferentially orientated portlandite crystals due to the wall effect [17] as illustrated in Fig 1 So how
·Ambient seismic noise interferometry combined with a quantitative stress model can be used to determine changes in seismic wave velocity and by extension other geotechnical parameters which are
·Methods The preparation and thermal insulation performance of cast in situ phosphogypsum wall were investigated The property of phosphogypsum fly ash lime PFL triad cementing materials the adaptability of retarders and superplasticizers and the
·The problem of recycling and storage of phosphogypsum is topical for many countries around the world as it is associated with environmental problems of pollution of water bodies land and
·The preparation of high strength phosphogypsum aggregates HPA was explored in this study by the compaction fragmentation grinding hydration process from mixture of PG GGBS OPC dry powders
To evaluate the radiological hazard of the natural radioactivity the radium equivalent activity the air absorbed dose rate the annual effective dose rate and the representative level index and the values of both external and internal hazard indices were evaluated and compared with the internationally approved values Expand
·This study involved proportionally blending beta hemihydrate phosphogypsum β HPG with raw phosphogypsum to prepare a phosphogypsum based composite cementitious material PGCM The admixtures of quicklime 1 3% cement 12 18% and silica fume 5 9% were selected to fabricate the PGCM mixture The effect of each admixture on the durability
·Phosphogypsum PG is a typical byproduct of the phosphate fertilizer industry s sulfuric acid process phosphoric acid production The global annual production of PG is about 250 million tons of which China s production exceeds 80 million tons Zhang et al 2018; Forns et al 2021 At present the majority of PG is stockpiling in slag yards
