Increase In P2O5 Content Research Articles

Investigation of P2O5 on the Break Temperature and Phase Composition of Slag from the Double Slag Converter Steelmaking Process

Herein, the influence of P2O5 on the break temperature and phase composition of slag from the double slag converter steelmaking process is investigated comprehensively. The composition and micromorphology of crystallized phase are analyzed by X‐Ray diffractometer and scanning electron microscope equipped with energy dispersive spectrometer. The results reveal that the break temperature of slag increases owing to an increase of P2O5 content. When the P2O5 content is 2%, the break temperature is 1198 °C, and it increases to 1209 °C for the slag with 4% P2O5. With the increase of P2O5 content from 2% to 8%, the activation energy for viscous flow shows an upward trend. The crystallized phase at the same temperature with different P2O5 contents remains nearly unchanged, but the diffraction peak intensity is different. When the P2O5 content remains constant, a decrease in temperature results in significant changes in the micromorphology of crystallized phases. The present results improve the knowledge about the P‐rich slag, and are also significant in optimizing the double slag converter steelmaking process.

Effect of P2O5 on the viscous flow and crystallisation behaviour of slag in the double slag converter steelmaking process

In the current study, the effect of P2O5 on the viscous flow and crystallisation behaviour of slag in the double slag converter steelmaking process was investigated in laboratory. The results indicated that with the increase of P2O5 content, the softening temperature, hemispherical temperature and flowing temperature of steelmaking slag showed a decreasing trend, however, the viscosity increased. The FactSage thermodynamic software was used to predict the types and contents of crystallisation phases in the crystallisation process of steelmaking slag. It showed that with the increase of P2O5 content, the precipitation content of Ca5P2SiO12 increased, while the precipitation content of melilite decreased. The composition and microstructure of crystallisation phases were analysed using X-ray diffraction and scanning electron microscopy. The phase composition did not change with the increase of P2O5 content, but the diffraction peak intensity of each crystallisation phase was different. Besides, the precipitation of phosphorus-enriched phase was enhanced with the increase of P2O5 content.

Effects of P2O5 content on the structure, stress distribution and vickers hardness of Na2O-MgO-Al2O3-SiO2 glasses with chemical strengthening treatments

In this work, effects of P2O5 content on the structure, stress distribution and vickers hardness of alkali aluminosilicate glasses with different chemical strengthening treatments were investigated. The results showed that the addition of P2O5 increased the degree of polymerization for glass network. The coefficient of thermal expansion, glass transition temperature and density of the parent glasses were all decreased. Meanwhile, the molar volume of the samples increased. The chemical strengthening experiments revealed that increasing P2O5 content promoted the diffusion of K+ ions, which resulted in an increase in the depth of stress layer. However, surface compressive stress of the glasses decreased with P2O5 content increasing, mainly attributed to stress relaxation of the glass structure. After chemical strengthening treatments at 370 °C and 390 °C respectively, the vickers hardness of the glasses decreased with the increase of P2O5, while an opposite trend was observed at 410 °C.

Dispersion, ionic bonding and vibrational shifts in phospho-aluminosilicate glasses.

Understanding the relationships between structure and properties of aluminosilicate glasses is of interest in magmatic studies as well as for glass applications as mechanical or optical components. Glass properties may be tailored by the incorporation of additional elements, and here we studied the effect of phosphate incorporation on refractive index and the degree of ionic bonding in aluminosilicate glasses. The studied glasses in the system SiO2-Al2O3-Na2O-P2O5 had a metaluminous composition (Al:Na = 1) with the content of SiO2 ranging from 50 to 70 mol% and of P2O5 from 0 to 7.5 mol%. Refractive index was measured at four wavelengths from visible to near-infrared and found to decrease both with increasing P2O5 content (at the expense of NaAlO2) and with increasing SiO2 content (by substitution of SiO4 for AlO4 groups). This trend correlated with a decrease in density while, additionally, the formation of Al-O-P bonds with an SiO2-like structure may account for this change. The degree of ionic bonding, assessed via optical basicity and oxygen polarisability, decreased with increasing P2O5 and SiO2 content. Despite the complexity of the studied glasses, oxygen polarisability and optical basicity were found to follow Duffy's empirical equation for simple oxide glasses. In the high frequency infrared and Raman spectra, band shifts were observed with increasing P2O5 and SiO2 content. They indicated changing average bond strength of the glass network and showed a linear correlation with optical basicity.

Study on the recovery of phosphorus and iron from molten modified high-phosphorus industrial slag by carbothermal reduction

To effectively recycle phosphorus and iron resources in high-phosphorus industrial slag during molten modification process, the thermodynamic conditions and influence laws of recovery of valuable elements from converter slag with different P2O5 content by carbothermal reduction after melting and modification are systematically analyzed. The results show that the reduction rates of P2O5 and FeO decrease with the increase of P2O5 content at 1450 °C and the basicity of 1.0. Meanwhile, the experimental results prove that the reduction of FeO precedes the reduction of P2O5.The phosphorus element in initial industrial slag mainly exists in the form of Ca5(PO4)2SiO4 and increases with the increase of P2O5 content. With the progress of the carbothermal reduction reaction, the Ca5(PO4)2SiO4 content in experimental slags after reduction decrease significantly. The iron element in initial industrial slag mainly exists in the form of FeO, (MgO)0.239 (FeO)0.761 and Ca2Fe2O5 and disappear after carbothermic reduction reaction. In the range of P2O5 content of 4–8 wt.%, P2O5 content has little effect on the thermodynamic trend of the formation of phosphorus-containing phase Ca5(PO4)2SiO4, but it is not good for the thermodynamic trend of gasification dephosphorization reaction in the carbothermic reduction process. Therefore, the increase of P2O5 content is not conducive to the occurrence of carbothermic reduction gasification dephosphorization reaction.

Oxidation behavior of vanadium and phosphorus during simultaneous vanadium extraction and dephosphorization of hot metal

In this paper, the indirect equilibrium method was used to study the equilibrium distribution ratios of vanadium and phosphorus in the metal phase and the slag phase, and simultaneous vanadium extraction and dephosphorization experiments were carried out under different slag basicity (the mass ratio of CaO to SiO2) conditions to explore the oxidation behavior of vanadium and phosphorus during simultaneous vanadium extraction and dephosphorization of hot metal. The results show that with the increase of slag basicity, the equilibrium distribution ratio of V (lgLV) increases slightly and the equilibrium distribution ratio of P (lgLP) increases significantly. With slag basicity increasing from 0.5 to 2.5, lgLV and lgLP increase from 1.7 to 2.0 and 0.1 to 1.9, respectively. Both lgLV and lgLP decrease with the increase of temperature, and increase with the increase of FeO content. High MgO content is not conducive to vanadium extraction. MnO has less effect on lgLV and lgLP. lgLV increases with the increase of V2O3 content, and decreases with the increase of P2O5 content. lgLP decreases with the increase of V2O3 content, and increases with the increase of P2O5 content. Both lgLV and lgLP decrease with the increase of TiO2 content. When the slag basicity is 1.5, the oxidation rate of vanadium reaches 95% after 10 min of reaction. The total mass transfer coefficient of P is in the range of 0.0040–0.0084 cm/s, and increases obviously with the increase of slag basicity. However, the influence of slag basicity on the total mass transfer coefficient of V is not obvious. Both the rate-limiting step of vanadium extraction and dephosphorization are the mixed mass transfer in the metal phase and the slag phase.

Role of P2O5 in the viscous behavior and structure of yellow phosphorus slag

To clarify the role of P2O5 in the fluidity of yellow phosphorus slag during the centrifugal granulation process, the viscosity and structure of slag with various P2O5 contents were researched. It showed that increasing P2O5 content from 1.38wt% to 5.80wt% enhanced the slag viscosity and activation energy for viscous flow, which reduced the slag fluidity. P2O5 in slag existed as QP0 and QP1 units whose proportions were about 0.89 and 0.11, respectively, irrespective of the P2O5 contents. The introduced P2O5 promoted the polymerization of silicate structure because the metal cations coordinated by non-bridging oxygens in silicate structure became connected with the phosphate structure. P2O5 addition encouraged the conversion of [AlO4] units into [AlO5] units and reduced the polymerization degree of aluminate structure. The variations in the polymerization degree of silicate and aluminate structure played a competitive role in determining the slag viscosity, and the silicate structure was the dominant factor.

The effects of phosphorus pentoxide additions on the thermal, rheological, and structural properties of sodium borosilicate glass

This research has characterized the effects of P2O5 additions on the physical, chemical, thermal, rheological properties and the structure of SiO2-B2O3-Na2O glasses relevant to radioactive waste immobilization. Properties analysed include high-temperature viscosity, glass transition temperature (Tg) and structure. X-ray diffraction (XRD) confirmed a solubility limit of between 3.0 and 4.0 mol% P2O5 for the onset of crystallinity with formation of Na3PO4 and Na4P2O7 in annealed bulk glasses; and between 4.0 and 5.0 mol% P2O5 in unannealed (quenched) glasses. This difference in behaviour is attributed to the bulk glass annealing temperature being greater than Tg of phase-separated, phosphate-rich droplet phases present in the 4.0 mol% P2O5 glass, which promoted crystallization, where back scattered scanning electron microscopy (SEM) images suggested that phase separation had occurred as liquid-liquid phase separation, where there was evidence of a droplet like morphology in glasses containing between 4.0 and 6.0 molar % P2O5. However, the exact mechanism cannot be unequivocally confirmed as nucleation and growth based purely on phase morphology. Differential Thermal Analysis (DTA) and dilatometry showed modest increases in Tg with increasing P2O5 contents below the onset of crystallisation and a more substantial increase coinciding with the onset of crystallisation between 3.0 and 4.0 mol% P2O5. High-temperature viscosity measurements showed that increasing P2O5 contents led to increases in viscosity, with samples containing the highest P2O5 additions displaying non-Newtonian behaviour consistent with the presence of crystals in the melt at 950 °C. Raman difference spectra showed that the increase in P2O5 content resulted in characteristic peak intensities at 729 cm−1, 937 cm−1, 1000 cm−1, 1026 cm−1, 1109 cm−1 and 1445 cm−1 which were associated with phosphate species.

Optimization of the nucleating agent content for the obtaining of transparent fluormica glass-ceramics

The crystallization behaviours, mechanical and optical properties of fluormica glass-ceramic system without and with P2O5 as nucleating agent are studied. The crystallization mechanism of fluor-phlogopite (KMg3(Si3AlO10)F2) without P2O5 oxide represented one-dimensional surface crystallization with a fixed number of nuclei, and with the addition of P2O5, the mechanism tends to two-dimensional bulk crystallization with a constant nucleation rate being the most predominant phase, forsterite crystals (Mg2SiO4). The base glasses had the spinodal phase separation, which coarsened considerably by increasing P2O5 content. P2O5 had a strong influence on the microstructure and morphology of this type of glass-ceramic. The addition of small amount of P2O5 (1.0 mol%) to these glass-ceramic changed the microstructure from dendritic growth having leaf-like feature to a flower-like morphology of the crystal phase. Glass-ceramic without P2O5 produces yellowish to colourless transparent glass-ceramic, and with the incorporation of the P2O5 (1.0 mol%), which has been found the optimum to obtain transparent glass-ceramics, the transmittance is still about 85%. As the P2O5 content increased to 3.0 mol%, besides fluor-phlogopite mica, forsterite also precipitates, the size of the crystals increase, their distributions turned to be broad due to the change of the crystallization mechanism and the transparency of glass-ceramic consequently decreases.

Optical transmittance and energy storage properties of potassium sodium niobate glass-ceramics

In this work, 0.8(K2O-Na2O-2Nb2O5)−0.2((1-x)B2O3-xP2O5) (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) glass-ceramics have been fabricated. The effects of P2O5 on the microstructure and properties of the glass-ceramics were comprehensively studied. The addition of P2O5 promotes the transition of the glass network structure from a negatively charged [B∅4]- tetrahedron to an electrically neutral [BP∅4] tetrahedron. With the increase of P2O5 content, the formation of K2B4O7 is inhibited, with major phase of Na0.9K0.1NbO3 and minor phase of K2B4O7. It is found that the band gap width of the glass-ceramics increases from 3.34 eV to 3.52 eV firstly and then decreases to 3.43 eV. The grain size of the glass-ceramics decreases from 150 nm to 50 nm. High optical transmittance (63%), large discharge energy density (4.58 J/cm3) and large energy storage efficiency (98%) have been simultaneously obtained for K2O-Na2O-Nb2O5-B2O3-P2O5 glass-ceramics, which are potential for the applications of the transparent pulse capacitors.

Effect of P2O5 on the viscosity of yellow phosphorus slag in electric furnace at high temperatures

Phosphorus is an important raw material for chemical industry. The traditional production method is to heat phosphate rock, silica and coke in an electric furnace, and produce phosphorus by reduction reaction at high temperatures. Slag discharge is one of the key processes for the operation of electric furnace, so it is important to understand the flow behavior of phosphorus bearing slag. In this work, we investigated the effect of P2O5 on slag structure and viscosity in SiO2-CaO-Al2O3-MgO-P2O5 system by experiments. Results shows that as the P2O5 content increases, slag viscosity slightly increases at high temperatures, because the addition of P2O5 increases the polymerization degree of the slag. However, when the temperature is below the liquidus temperature (Tliq), the slag viscosity decreases. The increase of P2O5 content led to a decrease in the n value of nC2S-C3P solid solution and the average particle size of solid phase, which is detrimental to the gehlenite formation. In order to avoid the effect of fluctuation in the P2O5 content on slag discharge process in electric furnace, the discharge temperatures of slag should be higher than Tliq of the slag or the content of silicon and calcium should be 85 wt%.

Effect of P2O5 addition on enrichment behaviour of phosphorus in CaO–SiO2–FeO–P2O5 slag

ABSTRACT The CaO–SiO2–FeO–P2O5 slag was measured by Raman spectra, and the changes in the structure and behaviour of phosphorus were analysed under different slag components. The results proved that phosphorus exists in two enrichment behaviours in the slag, which can be judged according to the mole fractions of Q1(Si), Q2(Si), and Q3(Si). When the content of P2O5 increases from 4.5% to 8.5%, the Q0(P) intensity changes most significantly. Since the Fe–O bond energy (390.4 kJ mol−1) is weaker than the P–O (410 kJ mol−1) bond energy, the silicon-oxygen network structure will show a behaviour change of depolymerization first and then polymerization. XRD analysis shows that with the increase of P2O5 content, different calcium silicate phases are added and decreased in the slag, and the content of a small amount of calcium ferrite phase changes, bonds or separates from each other, which is consistent with the change law of Raman analysis.

Formation and crystal growth of needle-like rutile in glass- ceramics

Glass-ceramic, which has negligible dielectric loss, high mechanical strength, excellent drop resistance, low CTE, and low density for lightweight design, is the best option for the back cover of mobile devices in the 5 G era. Herein, the effect of P2O5 on the phase separation and crystallization of MgO–Al2O3–SiO2-TiO2 glass-ceramics is studied. The incorporation of P2O5 in the glass structure leads to phase separation, in which the P and Mg-enriched phase was formed in the glass matrix, and promotes the increase of Tg. With the increase of P2O5 content, the precipitated crystals change significantly. First, the silicate crystals (Mg2SiO4) disappear, whereas the phosphate crystals (LiMgPO4) emerge when 2 mol% P2O5 is introduced. Second, titanate crystal (MgTi2O5) can not be observed when 4 mol% P2O5 is introduced. The Ti5O9 crystals appear simultaneously with LiMgPO4 crystals and transform to rutile TiO2 crystals at high temperature. Interestingly, the needle-like rutile TiO2 crystals, which is 300 nm long and 20 nm wide, have been found in a glass with 4 mol% P2O5. The large L/D ratio of needle-like crystals increases the hardness significantly from 6.08 GPa to 7.14 GPa. Similar to other fiber reinforced composites, this needle-like crystals provide a new strategy to improve the mechanical properties of glass ceramics.

Recycling phosphogypsum as the sole calcium oxide source in calcium sulfoaluminate cement production and solidification of phosphorus

Because the disposal of phosphogypsum (PG) can lead to serious contamination of the air, soil, and water, recycling of PG has attracted wide attention. This study investigated the effect and solidification of phosphorus in the production of calcium sulfoaluminate (CSA) cement using PG as the sole CaO source. The effects of three phosphorus impurities (Ca3(PO4)2, CaHPO4, Ca(H2PO4)2) on the decomposition of CaSO4, formation of minerals, microstructure of the clinker, and the hydration and mechanical properties of the cement were studied. Experimental results show that Ca3(PO4)2 and Ca(H2PO4)2 promoted the decomposition of CaSO4 and the formation of clinker minerals with the increase in P2O5 content, whereas CaHPO4 showed a promoting effect only when the P2O5 content was more than 1.5 wt%. The increase in phosphorus incorporation in Ca2SiO4 leads to the transformation of β-Ca2SiO4 to α′-Ca2SiO4 and then to Ca7Si2P2O16. The presence of three phosphates in the clinker enhanced the growth of crystal grains and the generation of a liquid phase. Compared with Ca4Al6SO16 without phosphorus, the hydration reaction of phosphorus-bearing Ca4Al6SO16 started later and ended earlier, and the reaction time was shorter. The presence of phosphorus impurities reduces the 1-day strength of CSA cement but does not affect the development of the 3-day and 28-day strengths. Considering environmental aspects, the solidification of phosphorus in the production of CSA clinker were quantified by measuring the distribution of elements. The results indicated that phosphorus is solidified by Ca4Al6SO16, Ca2SiO4, and Ca4Al2Fe2O10, and Ca2SiO4 has a stronger ability to solidify phosphorus than the other two minerals. Ca3(PO4)2 is more difficult to solidify than CaHPO4 and Ca(H2PO4)2. This study is of great significant to guide the large-scale clean utilization of PG in the production of CSA cement.

Insights into structure and properties of P2O5-based binary systems through molecular dynamics simulations

In order to clarify the microscopic characteristics and evolution rules of varying P2O5-based binary melt structures, molecular dynamics simulation (MD) was utilized to conduct a comprehensive study on its structure and performance. The investigation results demonstrated that the basic unit of P2O5-based binary melt network structure is [PO4]3−, and its structure is close to the standard tetrahedron. With the increase of P2O5 content, Q0, Q1 and Q2 will gradually shift to Q3 structure, resulting the network structure of each phosphate system more complicated. For a given P2O5 content in different systems, as the size of the metal cation decreases, the PO structure becomes more disordered and the degree of polymerization of systems increase. The order of polymerization degree of distinct binary systems is BaOP2O5＜K2OP2O5＜Na2OP2O5＜CaOP2O5. In addition, by linking the change law of the degree of polymerization of P2O5-based binary systems with macroscopic thermodynamic properties of dephosphorization, it is concluded that the dephosphorization capacity of varying binary systems is inversely proportional to their degree of polymerization.

Influence of Al2O3 and P2O5 contents in sol-gel ionomer glass system on the structure and their cement properties

Glass ionomer dental cement (GIC) is commonly used as a restorative material. The sol-gel synthesis of the ionomer glass is an alternative method, which can produce higher purity and homogeneous at low temperature compared with the traditional melt-quench method. This study synthesized the ionomer glass with the variation of Al2O3 and P2O5 contents in the glass formula by the sol-gel route. The term of Al/(Si+P) ratio was evaluated by XRD and XPS to understand the structural change in the sol-gel glasses. The relationship of the chemical structure of the sol-gel glass, the ions releasing behavior, setting time, and compressive strength of the sol-gel GIC were determined. This study demonstrated that the increase of Al2O3 content in glass formula increased [AlO6] octahedron and bridging oxygen (BO) in the glass structure, while the increase of P2O5 content in glass formula led to the increasing of the [AlO4] tetrahedron and BO. The sol-gel GIC composition met the maximum compressive strength at Al/(Si+P) = 1.57, whereas the general GIC composition required at Al/(Si+P) nearby 1. Moreover, in vitro cell viability of NIH/3T3 fibroblast cells also showed promising result after 2 days culture. This study provided the knowledge for adjusting the sol-gel glass composition for the appropriate properties of GIC.

Structure and crystallization behavior of phosphorus-containing nepheline (NaAlSiO4) based sodium aluminosilicate glasses

The study aims at understanding the structural role of P2O5 in meta- and per-aluminous sodium aluminosilicate glasses, followed by its correlation with their crystallization behavior. Experimental results suggest an increase in the degree of polymerization of the phosphate network and a change in the aluminum environment in the glasses from Al(OSi)4 to Al(OP)4 with an increasing P2O5/SiO2 ratio. The substitution of SiO2–by–P2O5 in the amount varying between 10 – 20 mol.% suppresses the crystallization of nepheline. This has been attributed to the unavailability of Al3+ (to form Si–O–Al linkages) due to the formation of Al–O–P linkages in the glass structure. An increase in P2O5 content (>20 mol.%) in peraluminous glasses results in the crystallization of AlPO4 as the primary phase. The results have been discussed in the light of various models developed to predict the compositional dependence of nepheline crystallization in Hanford's high-level waste glasses.

Geochemical Assessment and Mobility of Undesired Elements in the Sludge of the Phosphate Industry of Gafsa-Metlaoui Basin, (Southern Tunisia)

The raw phosphates in the Gafsa-Metlaoui phosphate basin are valorized by wet processes that are performed in the laundries of the Gafsa Phosphates Company (CPG, Gafsa, Tunisia) to reach market grades (>28% P2O5). This enrichment process allows the increase of P2O5 content by the elimination of the coarse (>2 mm) and fine (<71 µm) fractions. Mineralogical analysis has shown that all the investigated materials (raw phosphate, marketable phosphate, coarse waste, and fine waste) from the laundries of M’Dhilla-Zone L and Redeyef are both composed of carbonate fluorapatite, carbonates, quartz, gypsum, clays, and clinoptilolite. Chemical analysis shows that Cr, Cd, Zn, Pb, and U are concentrated in the fine wastes and associated with the clay–phosphate fraction. The rare earth elements are more concentrated in both raw and marketable phosphates. Drilling and sludge-water analysis, along with leaching tests conducted on the fine wastes, showed that, due to phosphate industry, cadmium, fluorine, and sulfate contributing to the pollution of water resources in the region, pollution is more conspicuous at M’Dhilla.

Influence of P<sub>2</sub>O<sub>5</sub> Content on In Vitro Behavior of CaO-ZnO-P<sub>2</sub>O<sub>5</sub> Bioglass Powder Compacts

CaO-ZnO-P2O5 bioglasses were synthesized in order to study the relationship between their composition and in vitro behavior. We specifically examined the relationship between the P2O5 content and the in vitro behavior of the powder compacts. The weight gain percentage after immersion in a simulated body fluid (SBF) for a 4-week-period increased with the increase in P2O5 content up to a certain threshold, and the maximum weight gain was observed when the P2O5 content was 33.6 mol%. As the amount of P2O5 increased further, the weight gain in the samples rapidly turned to a negative value. In other words, it was found that there was a threshold for the P2O5 content. In the sample that had the maximum weight gain, submicron level, round precipitates were observed after the SBF test and presumed to be an amorphous calcium-zinc phosphate substance. Furthermore, a phosphate glass structure that promotes the precipitation of the above substances was proposed. The structure was formed when the long-chain structure of P-O (Q2 group), which promotes the dissolution of the P component, and the short-chain structure of P-O (Q0 and Q1 groups), which are considered to be the starting points of precipitation, coexist in a well-balanced ratio within the glass.

Geochemistry and paleoenvironment of the phosphorites from the Ameki Formation, Niger delta, Nigeria

The phosphorites of the Ameki Formation occur as nodules, pellets as well as primary phosphatic shales and siltstones. Geochemical analysis of the phosphate samples was carried out to determine its chemical composition as well as its depositional environment. The methodology applied include XRF, INAA, XRD and thin section petrography using Polarizing Microscope. The XRF result identified CaO- P2O5- F as the major mineral group, SiO2, Al2O3, Fe2O3, MgO and TiO2, which show minor occurrences and Cr, U, Pb, V, Cu, Zn, Se and Cd that occur in trace amounts. The nodules and pellets are of medium to high grade (25- 34wt% P2O5) whereas the primary phosphatic shales and siltstones are of low to medium grade (4.5– 22wt% P2O5). The phosphorites comprise mostly of francolites. The mean index of refraction estimated by Becke-line method using Standard Polarizing Microscope gave 1.634 and1.636.XRD analysis yielded an average values of 9.243 (± 0.002) A° and 6.715 (± 0.002) A° for a and c crystallographic axes respectively with an axial ratio (c/a) of 0.726for unit cell parameter, suggestive of low degree of carbonate substitution. An increase in P2O5 content is found to be accompanied by increase in CaO, CO2 and F contents, but by a decrease in H2O, organic carbon, SiO2 and Fe contents indicative of amorphous solid phase of calcium phosphate. The phosphorite is interpreted to form under high biologic productive, shelf setting. High nutrient availability in the ancient sea is linked to upwelling along the West African Coastline during the Eocene.
 Keywords: Phosphorites; Geochemistry; Paleoenvironment; Ameki; Francolites; Nodules