Phosphate Fertilizer Plant Research Articles

Radiological Assessment in the Premises of the Phosphate Fertilizer Plant of the Industrial Complex “Trepça”

Radiological Assessment in the Premises of the Phosphate Fertilizer Plant of the Industrial Complex “Trepça”

Distribution of trace and rare earth elements in the estuary of Ría de Huelva (SW Spain): Field data and geochemical modeling

The geochemistry of the Ría de Huelva estuary (Spain) has been widely studied owing to its unique conditions due to mixing of acid mine drainage (AMD), river water and seawater, which have been aggravated by the existence of an adjacent phosphate fertilizer plant and its associated phosphogypsum stack.To better understand the complex geochemistry of the overall estuarine system, we make use of (1) measured concentrations of relevant trace elements (rare earth elements (REEs) and metal(loid)s) in the sediments and waters of the estuary and (2) geochemical modeling which combines mixing and adsorption processes.Our study sheds light on the elemental distribution in the sediments and water in the water-mixing area. As seawater neutralizes the acidity of the river water (pH increases to 6.2) colloids of Fe- and Al-oxyhydroxysulphates (schwertmannite and basaluminite, respectively) precipitate as concentrations of aqueous Fe and Al increase. These phases have a high adsorption capacity and play a critical role in the geochemistry of the aquatic system by retaining Cu, Pb, Cr, As, P, REEs and smaller amounts of Zn, Co, Ni and Mn. The geochemical model reproduces the behaviour of the aqueous REEs, requiring high S/L ratios at pH ≥ 3.5 and participation of sediments and colloids in the reactions to match the field data.The evaluation of the effect of the adjacent phosphogypsum stack on the estuarine geochemistry shows that the stack has a notorious impact on the geochemistry of the surrounding estuarine environment owing to the release of high quantities of phosphate.

Thermal and Mechanical Properties Enhancement of Cement Mortar using Phosphogypsum Waste: Experimental and Modeling Study

This research presents an in-depth investigation into the application of phosphogypsum (PG), a by-product of phosphate fertilizer plants and chemical industries, as a replacement material for cement in mortar, with a focus on enhancing its thermal and mechanical properties. The influence of PG as a partial replacement for cement on the compressive strength of mortar after 3, 7, and 28 days is investigated. Utilizing the Box-Behnken design within Response Surface Methodology, this study analyzed factors, such as sulfuric acid concentration, washing time, calcination temperature, and PG to cement ratio. Results indicate that optimal PG levels enhance mortar strength, particularly at 28 days, through sustained ettringite formation and microstructure optimization. Sulfuric acid concentration and calcination temperature were identified as the most significant elements influencing compressive strength, with the latter improving PG quality and reactivity. A PG to cement ratio up to 10% was found beneficial, while washing time had a negligible effect. The research highlights a critical synergy between the sulfuric acid concentration applied during the purification of PG and the calcination temperature. A significant improvement of 21% in compressive strength was achieved, underscoring the combined effect of chemical and thermal treatment on PG's efficacy in mortar. The increased sulfuric acid concentration is presumed to purify the PG by removing impurities, thus improving its reactivity. Concurrently, calcination alters the PG's crystalline structure and diminishes its organic composition. This interdependent optimization is instrumental in enhancing the structural integrity of PG-modified mortar. The potential for raw PG to be used as an insulating material is more pronounced at higher replacement rates (10%), while sulphuric acid treated PG (SCPG) and heat treated PG (HTPG) seem to be unable to provide a clear insulative advantage.

Distribution, source and contamination of rare earth elements in sediments from lower reaches of the Xiangjiang River, China

Rare earth elements (REEs) are emerging micropollutants in aquatic environments. In this study, concentrations of REEs and major elements, and mineralogical compositions of sediments from lower reaches of the Xiangjiang River (China) were analyzed using ICP-MS technique. The results suggested that sediments were characterized by terrigenous compositions TiO2, SiO2, Al2O3, K2O, Na2O and P2O, and contained high concentrations of REEs with mean total REE concentrations (∑REE) of 318.7 mg/kg. REEs were moderately enriched in upper river sediments, and slightly or less enriched in downriver sediments. The normalized REE distribution pattern for sediments was characterized by flat shalelike and Eu depleted V-shape REE patterns, which indicated REEs in sediments were lithologically contributed from sedimentary rocks and granites distributed in the watershed respectively. REEs in sediments were hosted mainly in Fe–Mn oxides, and sulfide and organic matters that were characterized by middle REEs (MREE) enrichments relative to light REEs (LREE) and heavy REEs (HREE), and the distribution and differentiation of REEs in sediments were controlled by clays, Fe–Mn oxides, organic matters and finer grains; and also by accessory minerals (e.g., zircon) from granite. The distribution features of REEs in sediments and BCR extraction results suggested that the sediment REE enrichment resulted from additional REE input from anthropogenic sources, including those in discharges from sulfide-ore smelting industries at Zhuzhou city and from phosphate fertilizer plants at Xiangtan city along the river. Thus, sediments were contaminated with REEs in moderate degree in upper river area, and REE contamination was then formed by superimposing anthropogenic REEs on lithological residues. Finally, concentrations of Ce > 100 mg/kg, Gd > 8.12 mg/kg, ∑REE >274.9 mg/kg, ∑LREE >252.3 mg/kg and ∑HREE >28.8 mg/kg here were recommended as the REE contamination levels that represented as REE indices for identifying and rating REE contamination in this mining impacted river.

EuroChem threatens to close big phosphate fertilizer plant

EuroChem threatens to close big phosphate fertilizer plant

Di-ammonium phosphate (DAP) and plant density improve grain yield, nodulation capacity, and profitability of peas (Pisum sativum L.) on ferralsols in eastern D.R. Congo

Sustaining high crop yield and profitability on marginal soils, such as degraded ferralsols, calls for the use of adequate farming practices. In this study, we assessed for four cropping seasons the effect of di-ammonium phosphate (DAP) fertilizer application doses (100, 150, and 200 kg ha−1) and plant densities (100,000, 166,666, and 250,000 plants ha−1) on growth, yield, nodulation capacity, and profitability of two pea varieties (Adei and Rwanda) under degraded ferralsols in eastern Democratic Republic of Congo (DRC). Results showed that pea growth, yield, nodulation, and profitability were significantly affected by the DAP dose and the plant density. Application of 150 kg ha−1 of DAP improved pea yields from 730 to 1720 kg ha−1 and nodulation from 17 to 22 nodules per plant. The number of active nodules was positively correlated with total number of nodules, DAP doses, yield parameters, and plant height. High grain yield was recorded during the long rainy season (1400 kg ha−1) compared to the short one (930 kg ha−1). All DAP doses were profitable according to the agronomic efficiency (AE) and value–cost ratio (VCR) analyses. For improved and profitable pea production on degraded South-Kivu ferralsols, applying 150 kg ha−1 of DAP combined with low plant density are to be recommended and preferably in the long rainy season.

Recovery of high pure pyrolytic carbon black from waste tires by dual acid treatment

Pyrolytic carbon black (CBp) is one of the products from waste tires through the pyrolysis process having potential business prospects. However, any impurities in CBp tremendously limit its further applications, such as rubber reinforcers, fuels, and other functional materials. The existing processes for CBp purification suffer from low purification efficiency, high cost, and severe environmental pollution. In this work, hydrochloric acid (HCl) and the phosphate fertilizer acid (PFA) which is a by-product waste acid from the phosphate fertilizer plant are employed as leaching agents for recovery of high pure CBp. In this process, the former is used to remove metal and sulfur compounds, and the latter can effectively dissolve silicon oxide in CBp. The high purity (99.63%) of the treated CBp product is achieved, well meeting the standard of commercial carbon black (99.3%). Moreover, the HCl solution can be recycled and reused for several times, realizing the continuous enrichment of zinc ion in the leaching solution, while the used PFA can be directly transferred into value-added H2SiF6 as new production due to the desirable enhanced silicon amount. The obtained CBp shows the same internal structure and sulfur state as that of commercial carbon black, suggesting the possibility of application as rubber reinforcing filler. Therefore, this approach for the recovery of high-purity CBp is efficient, economical and suitable for large-scale production. Furthermore, an amplified production installation with 50 L scale was successfully designed and operated, verifying its good universality and stability with the proposed purification technology. This work provides a sustainable method to refine CBp derived from waste tires, contributing to the development of the upstream pyrolysis industry and effective utilization of solid waste resources.

PET plastics as a Trojan horse for radionuclides

Mismanaged plastic waste interacts with secondary environmental pollutants, potentially aggravating their impact on ecosystems and human health. Here we characterized the natural and artificial radionuclides in polyethylene terephthalate (PET) bottles collected from the industrial littoral discharge of a phosphate fertilizer plant. The activity concentrations in littered bottles ranged from 0.47 (208Tl) to 12.70 Bq·kg-1 (226Ra), with a mean value of 5.30 Bq·kg-1. All the human health risk assessment indices (annual intake, annual effective dose, and excess lifetime cancer risk) estimated for radionuclides associated with ingestion and inhalation of microplastics were below international safety limits. Our results demonstrated that PET can be loaded with natural and artificial radionuclides, and potentially act as a carrier to transfer radionuclides to humans, posing a new potential health risk. Increased use, mismanagement and fragmentation of plastic waste, and continued interaction of plastic waste with radioelements may lead to enhanced radiation exposure in the future.

Preparation of alkali free liquid accelerator for shotcrete with fluorosilicic acid waste liquid and its accelerating mechanism

At present, the waste liquid of fluorosilicic acid produced by phosphate fertilizer plants in China creates serious problems of resource waste and environmental pollution. In view of this, a kind of alkali free liquid accelerator (FSA-AF) for shotcrete was prepared herein by using fluorosilicic acid waste liquid, which can realize the purpose of resource utilization and clean production. After testing the performance of FSA-AF, it was found that the addition of FSA-AF greatly shortened the setting time of cement paste, and it had no significant negative influence on early and late compressive strengths of mortar specimens. The results confirmed that FSA-AF was an alkali free liquid accelerator with excellent coagulation promoting property. Moreover, in order to elucidate the accelerating mechanism of FSA-AF, the early hydration process of cement paste, C3A paste and C3S paste with FSA-AF was measured by isothermal calorimetry, and the phase composition and micro morphology of their hydration products were investigated thoroughly by XRD and SEM analyses. Based on these results, the early hydration models of C3A and C3S in the presence of FSA-AF were proposed.

Rare earth elements characterization associated to the phosphate fertilizer plants of Gabes (Tunisia, Central Mediterranean Sea): Geochemical properties and behavior, related economic losses, and potential hazards

This is the first study on the behavior and industrial fluxes of rare earth elements (REE) in the coastal fertilizer plants of Gabes (south-eastern Tunisia), the economic losses related to their wastes, and their environmental and human health hazards. The concentrations of 16 REE were assessed in phosphate rock (PR), phosphogypsum (PG) and phosphogypsum foam (PGF) samples, collected from Gabes plants. REE concentrations ranged from 0.23 (for Sc in PG) to 309.33 mg kg−1 (for Ce in PGF). Ce was the most abundant in the three matrices, with concentrations ranging between 80.40 (in PG) and 309.33 mg kg−1 (in PGF). PGF was the most enriched with REE (1075.32 mg kg−1). The annual flow of REE from the fertilizer factories to the marine environment may reach 1523.67 t. The economic losses related to the discharge of phosphogypsum REE in the Gulf of Gabes (GG) was estimated at ~58 million US$ y−1. The potential hazards of discharged REE on the local environment and human health were also evaluated and discussed. These findings show the need for the development of a new industry exploiting REE from phosphogypsum wastes (short term) and phosphate ores (long term) which should lead to reduce its high environmental and human health footprint and to potential economic gains.

Lichens as a spatial record of metal air pollution in the industrialized city of Huelva (SW Spain)

Huelva is a highly industrialized city in SW Spain hosting, among others, a Cu smelter, a phosphate fertilizer plant, a power plant, and oil refineries. This study aims to evaluate metal concentrations in lichens as bioindicators of atmospheric pollution in the impacted urban areas. Xanthoria parietina species from Huelva and nearby villages, as well as reference samples from remote, non-contaminated urban areas, were analyzed for trace elements (V, Cr, Mn, Co, Ni, Cu, Zn, Sr, As, Cd, Sb, Cs, Ba, La, Ce, Pr, Nd, Sm, Er, Tm, Yb, Lu, Pb, Th, U) using Inductively Coupled Plasma-Mass Spectrometry; and for major elements (Ca, K, Mg, P, and S) by Inductively Coupled Plasma-Optical Emission Spectrometry after acid digestion.The metal composition of X. parietina exhibits spatial distribution patterns with extremely elevated concentrations (Co, Ni, Cu, Zn, As, Cd, Sb, Ba, Pb, U, and S) in the surroundings of the industrial estates to <1 km distance. Mean concentrations were significantly lower in the urban areas >1 km from the pollution sources. However, air pollution persists in the urban areas up to 4 km away, as the mean concentrations of Cu, Zn, As, Cd, Sb and S remained considerably elevated in comparison to the reference samples. Though rigorous source apportionment analysis was not the aim of this study, a good positive correlation of our results with metal abundances in ambient particulate matter and in pollution sources points to the Cu smelter as the main source of pollution. Hence, the severe air pollution affecting Huelva and nearby urban areas may be considered a serious health risk to local residents.

Natural radioactivity and radiation hazard assessment of industrial wastes from the coastal phosphate treatment plants of Gabes (Tunisia, Southern Mediterranean Sea)

This work is a first contribution to the knowledge of natural radionuclides (226Ra, 238U, 40K, and 232Th) activities in phosphate rock (NORM), phosphogypsum, and phosphogypsum foam (TENORM) from the coastal fertilizer plants of Gabes (Southeastern Tunisia) and the assessment of their radiation hazards on human health and the surrounding environment. In the three studied materials, activities were found to be in the range of 35.4 (40K)–375.1 (226Ra), 10.0 (40K)–220.2 (226Ra), and 79.2 (232Th)–1168.6 Bq kg−1 (226Ra), respectively. Considering the studied radionuclides and materials, the corresponding decreasing activity orders were found to be 226Ra > 238U > 40K > 232Th and PGF > PR > PG, respectively. All human health hazard indices exceeded the worldwide recommended safety limits, which show that the workers in Gabes phosphate fertilizer plants as well as the neighboring human community may potentially be exposed to significant radiation, which may cause several diseases and malformations. It is therefore recommended to avoid and/or reduce the potential fertilizer industry radioactive impact in the area.

Decadal effects of solid industrial wastes on the coastal environment: Gulf of Gabes (Tunisia, Southern Mediterranean Sea) as an example

The present work examines the different types of solid effluents dumped in the coastal environment from Gabes phosphate fertilizer plants, describes their coastal repartition and assesses their long-term environmental impacts. Scanning Electron Microscopy analysis of collected beach sediment samples showed that these wastes consist of phosphogypsum, fluorapatite (phosphate ore grains), smokey quartz, calcite, fluorite, calcite-Mg, apatite, pyrite, albite, sphalerite-Cd-U, fluorosilicates, sulfur dross and spent catalysts. Using fluorapatite as a mineralogical marker of the coastal spatial distribution of industrial wastes, solid effluents were found to carry bottom and/or suspended loads with a coastal transport limited at Essorrag Wadi, ∼10 km south from the industrial emissary. Phosphogypsum which is the main solid effluent was found to be completely dissolved in the seawater. The main decadal consequences of solid effluents on the coast were found to be the following: local disappearance of Posidonia oceanica seagrass, formation of an azoic benthic zone between Gabes and Ghannouche ports, gradual fattening of the beach, shoreline advancement, formation of a belt of coastal dunes, mouth clogging of coastal streams and formation of coastal lakes.

Arsenic enrichment in sediments and beaches of Brazilian coastal waters: A review

High concentrations of total arsenic (As), even above the Brazilian legislative threshold for marine sediments of 70 mg kg−1, were found in beach sands and near-shore surface sediments. Two mechanisms (anthropogenic activities and sedimentary processes in the coastal waters) are responsible for this contamination. The anthropogenic impact includes releases from metallurgical plants, phosphate fertilizer plants and gold and iron mining. In the coastal area sedimentary processes redistributed the As from the sediment into the porous structure of calcareous marine algae. These enriched calcareous algae are transported over time to the beach by wave action. As in the Brazilian coastal environment, increased As levels were also observed in other coastal environments of South America such as Rio Loa (Chile), Barbacoas Bay (Colombia) and the Southern Pampa region (Argentina). Finally, arsenic levels in fish from Brazilian coastal waters and North Sea, which is also an As-contaminated area, were compared. In both areas, short term health effects from fish consumption are not expected, but a lifetime cancer risk cannot be excluded.

Recycling-equilibrium strategy for phosphogypsum pollution control in phosphate fertilizer plants

Excessive phosphogypsum waste has caused significant environmental contamination and has consequently become a serious threat to sustainable socio-economic development. This paper proposes a recycling-equilibrium strategy from a regional policy perspective that integrates circular economic theory and modeling techniques to resolve phosphogypsum-related pollution problems. Specifically, three typical conflicts are analyzed to describe the problem complexity, and a multi-objective bi-level programming model is formulated under uncertainty for the assignment of practical disposal limits to achieve a compromise agreement between the multiple decision makers. A solution approach that employs fuzzy theory, an acceptable reduction target, and Karush-Kuhn-Tucker conditions is developed to identify the optimum phosphogypsum stack allowance allocation mechanism for regional authorities and an optimal purchase-transportation plan for the phosphate fertilizer plants. The results from the practical case validated the feasibility and efficiency of the formulated method and proved that a recycling-equilibrium strategy based stack allowance allocation mechanism could successfully achieve phosphogypsum pollution mitigation. The practical application findings were: (1) different phosphate fertilizer plants have different sensitivities towards changing stack reduction targets; (2) local authority revenue and phosphogypsum stack quantities are mainly impacted by environmental protection targets; (3) allocating larger stack allowances to phosphate fertilizer plants with smaller emissions coefficients can realize better phosphogypsum reduction.

Histological anomalies and alterations in enzyme activities of the earthworm Glyphidrillus tuberosus exposed to high concentrations of phosphogypsum

Phosphogypsum (PG) is the major solid waste generated by phosphate fertilizer plants and is used worldwide as sulfur and calcium supplement in agricultural soil. Considering the probability of elevated doses of PG during agricultural applications, this study was carried out to assess its impact on the connective tissue, tissue cholinesterase (ChE) activity, lactate dehydrogenase (LDH) activity, and lipid peroxidation (LPX) level of the tropical earthworm Glyphidrillus tuberosus (Stephenson) found in abundance in the rice fields in India. Consistent loss of connective tissue and sloughing of the intestinal epithelium were observed in worms exposed to 10%, 15%, and 20% concentrations of PG in soil over an incubation period of 30days. ChE, LDH activities, and the level of LPX indicated highly significant variation (p < 0.01) between pre and postclitellar regions of the worm and concentrations of treatment. ChE activity was higher in postclitellar with respect to preclitellar region; however, the values for LDH activity and LPX level were higher in preclitellar region in comparison to postclitellar region in both PG treated and control worms. It was concluded that PG concentration at and beyond 10% could cause damage to muscle fibers and bring about significant alterations in these enzyme activities in G.tuberosus thus affecting the physiology and ecological functions of these worms.

Sorption Characteristics of Iron, Fluoride and Phosphate from Wastewater of Phosphate Fertilizer Plant using Natural Sodium Bentonite

The phosphate fertilizer industry generates a highly hazardous and acidic wastewater. Effluent samples were obtained from wastewater streams produced in Abu Zaabal for Fertilizer and Chemicals Company (AZFC). The present study reports a process for iron, fluoride, and phosphate sorption from the wastewater samples using natural sodium bentonite. Accordingly, a series of batch experiments were performed to study the influence of various experimental parameters, such as solution shaking time, solution pH, and clay amount of addition, temperature, and mechanical stirring speed. The obtained results clear that, the sorption preferred conditions were; shaking time of 60 mts, solution pH of 4, room temperature, and bentonite amount of addition of 1.0 g/L. Based on kinetic and thermodynamic studies, the sorption process of iron, fluoride and phosphate on Na-bentonite is said to follow pseudo-second order mechanism and endothermic nature.

Adaptive biochemical and physiological responses of Eriobotrya japonica to fluoride air pollution.

The biochemical and physiological effects of fluoride were investigated in loquat trees (Eriobotrya japonica) grown in the vicinity of a phosphate fertilizer plant in Tunisia. Photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were assessed; along with photosynthetic pigments, lipid peroxidation, electrolytic leakage (EL) and total phenolic contents in foliage and roots of trees at different distances from the phosphate fertilizer plant. All assessed parameters showed significant discrepancies in comparison with unpolluted sites. Obtained results showed high oxidative stress indices including H2O2, lipid peroxidation, and EL, SOD, CAT and GPx activities and proline contents in leaves and roots at the polluted sites as compared to control. In contrast, leaf Pn, Gs, E and photosynthetic pigment contents were low as compared to the control. These results indicate that even though antioxidant responses increased near the factory, adverse effects on physiology were pronounced.

Distribution of Mercury Concentrations in Tree Rings and Surface Soils Adjacent to a Phosphate Fertilizer Plant in Southern Korea.

This study aimed to determine mercury concentrations in tree rings and surface soils at distances of 4, 26 and 40km from a fertilizer plant located in Yeosu City, Korea. Mercury concentrations in all tree rings were low prior to the establishment of the plant in 1977 and became elevated thereafter. The highest average mercury concentration in the tree rings was 11.96ngg-1 at the Yeosu site located nearest to the plant, with the lowest average mercury concentration of 4.45ngg-1 at the Suncheon site furthest away from the plant. In addition, the highest mercury content in the surface soil was 108.51ng cm-3 at the Yeosu site, whereas the lowest mercury content in the surface soil was 31.47ng cm-3 at the Suncheon site. The mercury levels decreased gradually with increasing distance from the plant.

Failure cases related to material issues in wet-process phosphoric acid plant

Abstract The present paper describes three failure cases of metallic components handling wet-process phosphoric acid at ambient temperatures in a phosphate fertilizer plant. All the three cases of failure were related not directly to the corrosive environment rather to wrong selection or inferior quality of materials. In the first case, pipeline of stainless steel 316L failed due to inferior quality of material used in the elbow region. The elbow material was not a low carbon grade stainless steel and was also in heavily sensitized condition which led to intergranular corrosion and intergranular cracking. The other two cases were related to failures of pump sleeves made up of cast alloys equivalent to stainless steel 316 and Hastelloy C-276 respectively. SS 316 showed through-wall pitting and cracking while Hastelloy C-276 had undergone extensive corrosion along the interdendritic boundaries. Both the materials contained high carbon content which led to heavy precipitation of carbides (Cr-rich carbides in SS 316 and Mo-rich carbides in C-276) along inter-dendritic boundaries during solidification of the casting reducing their corrosion resistance. Recommendations to avoid such failures are also suggested.