In mining basin and in some deposits, several types of ores are often formed under different physico-chemical conditions. Each of these types can contain polluting chemical elements in byproduct, which need to be removed. We note also that commercial value of a sedimentary phosphate ore depends on the presence of impurities such as carbonates, silicates, iron and organic matter. So as to reply to technical, commercial and environmental demands, it is therefore necessary to proceed to the typology and the location of these different ores. In phosphate ore deposits of the Djebel Onk mining basin in Eastern Algeria, several mining and geological researches companies such as EREM and BRGM have defined this typology, use classic methods such as mineralogical and petrographic studies of rock samples collected from drilling cores. In this study, the typology has been confirmed ore specified in the four main phosphate deposits of the Djebel Onk basin using the monovariate discriminate method called“Passage par zero”and the potential method (dynamic clouds method) which is a multivariate statistical discrimination method. These methods were applied using chemical data (P₂O₅, CO₂, CaO, MgO, Fe₂O₃, SiO₂ and RI) of whole rock samples collected from drilling cores during the assessment stage. Different ore types have been obtained for each of the four main deposits.

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Phosphorus is essential to all known life forms. The element phosphorus, however, is always combined with other elements and is generally found in mineral forms, as phosphates, and most often in insoluble forms. In 2001-2002, world production of phosphate rock concentrate and unbeneficiated phosphate rock for direct processing and direct application was estimated to 125 million tones. This paper provides data and information on the origins and types of phosphate rocks, the world total phosphate rock production and reserves, and an overview of and prospects for different uses of phosphate products.

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Emphasis in recent years has been focused on improving processes which lead to enhanced phosphate recovery. This paper studies the precipitation features of calcium phosphate in a fluidized bed reactor in a concentration range between 4 and 50mg/L, and establishes the conditions for optimum phosphate removal efficiency. A two level modeling methodology is proposed and used for the determination of a control strategy of the unit pilot.

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A range of opal or transparent porous phosphosilicate glasses have been prepared by quenching melted mixtures of Moroccan natural phosphate, diatomite and/or dolomie. Their physical and chemical properties such as density, glass transition temperature, thermal expansion coefficient and chemical durability are studied upon the chemical composition. Adding dolomite to an opal glass favors the elaboration of transparency one, increases the glass transition Tg, reduces thermal expansion and improves the chemical durability.

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Eleven precipitated phosphates were evaluated as sources ofphosphorus (P) for plant growth by comparing their effectiveness with that of monocalcium phosphate, a source of water-soluble P that is generally considered to be fully plant available. The precipitated phosphates comprised struvites recovered from waste water discharges (mainly magnesium ammonium phosphate), laboratory synthesised struvites, a synthetic iron phosphate and a recovered calcium phosphate. Precipitating phosphates in these forms could be a way for removing P from waste water before it is discharged to rivers, so reducing the risk of eutrophication. Application to agricultural land would be one potential use for such phosphates. Evaluation was by pot experiments with a sandy loam soil and with a sandy clay loam soil using perennial ryegrass as the test crop. The soils differed in pH (6.6 and 7.1) and in Olsen P (28 and 11 mg L^-1). Measured variables were grass dry-matter (DM) yield and grass P concentration whichwere used to calculate offtake of P in the harvested grass. DM yields of ryegrass and P offtakes given by the synthetic and recovered struvites were not significantly different statistically either between themselves or to MCP applied at the same rate. On this basis these struvites could be used to recycle P to similar soils and the effect of the P on crop yield should be similar to that of MCP

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New R&D international project aimed at elaboration of novel materials and technology to restore territories damaged by intensive industrial exploitation has been presented. The project is based on results of development and application of glassy ecologically friendly fertilizers in agriculture and results of experiments on restoration of soil polluted by petroleum. It is proposed to elaborate a mineral fertilizer made from porous phosphate glass granules saturated by bacteria strains The fertilizer is intended for restoration of territories of former coal quarries and mines.

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The removal and destruction of ceramic fibers wastes are presently an important problem for the society health. Among these, the asbestos, which are silicates, is the more dangerous. Usually their destruction is obtained by a melting way, but this needs high temperature (about 1500-1600°C) and presents an expensive treatment. In this paper we show that the sodium polyphosphate addition to different asbestos (chrysotile, amosite and crocidolite) permits to obtain the fiber's destruction at a temperature below than 900°C. This process may be applied to composite materials containing a few part of asbestos, like carpet tiles or building plaster. This process of waste's treatment can open a new and a large market for sodium polyphosphate.

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Preparation of ammonium polyphosphate form II was made by heating a mixture of ammonium orthophosphate and urea at 280 to 300°C under wet ammonia which was prepared by passing air through 3 to 5% ammonia water. Simple dry process of the preparation of ammonium polyphosphate form V was studied and the ammonium polyphosphate was prepared by heating a mixture of ammonium orthophosphate and urea at 330 to 340°C under wet ammonia which was made by passing air through 15 to 29% aqueous ammonia. The ammonium polyphosphates had flame retardation effect to organic polymer materials and the materials containing the ammonium polyphosphates showed an oxygen index higher than 20.

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Phosphates as surface-functional materials were investigated. Boron phosphate (BPO₄), which is known to be a solid acid catalyst, showed prominent activity for the oligomerization of light olefins giving a liquid fuel, although other phosphates were inactive. Its activity was enhanced by grinding before use or by adopting a new preparation method characterized by supercritical drying As a catalyst support, AlPO₄ was examined for selective catalytic reduction of NO in exhaust gas to N₂ by hydrocarbon in the presence of excess oxygen. It was found that the activity of Pt(0.5wt%)/AlPO₄ catalyst was higher than that of conventional Pt(0.5wt%)/Al₂O₃ catalyst, although AlPO₄ alone was hardly inactive. Next, metal phosphates were examined as humidity-sensing materials, and several new candidates including Ti(HPO₄)₂·?H₂O were found. The humidity-sensing characteristics of Ti(HPO₄)₂·H₂O was considerably improved by treating with a NaOH solution. In addition, we found that Cu-P-Y-O ceramics, which were produced by the solidstate reaction between Cu₃(PO₄)₂·3H₂O and Y₂O₃, showed good humidity-sensitive characteristics; its electric resistance decreased by three orders in magnitude as the surrounding relative humidity increased from 0% to 96%.

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Calcium-Cadmium phosphoapatites solid solutions with formula Ca _10-x,Cd_x,(PO₄)₆Y₂ where Y is OH, F, or Cl were synthesized and characterized by infrared spectroscopy, X Ray diffraction and chemical analysis. Using an isoperibol calorimeter the enthalpies of solution of these products in nitric acid 9 weight % have been determined. Thermochemical cycles were proposed to acess to the enthalpies of formation and mixing. The results show an increase in the enthalpy of formation with the quantity of cadmium introduced in the lattice. The variations of the enthalpy of solution and the enthalpy of mixing versus Cd/(Ca+Cd) atomic ratio were correlated to the existence of two sites in the apatitic structure.

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Fluor- hyroxy- and chlor-apatites of Ca, Ba, Sr, Cd and Pb have been synthesized and characterized by X ray diffraction, IR spectroscopy and chemical analysis. They are dissolved in a nitric solution using an isoperibol calorimeter. Combining the dissolution results with other results obtained in the same device or picked from literature leads to the enthalpies of formation of these products. The relative stability of the products is first discussed by considering the enthalpies of formation. However, one can access to a more realistic stability scale by calculating the Gibbs energies of formation. This calculation is based on the involvement of the apatites in reactions for which the entropies of the reactants are tabulated. Ca fluor- and hydroxy-apatites are taken as examples, and the results show that P₄O₁₀ reactional schemes could be considered to calculate Δ_fG°(T₀) for all the products. This calculation leads to more realistic stability scale for the apatites.

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SrNiZn(PO₄)₂ is isostructural to SrNi₂(PO₄)₂. The lattice parameters are: a=5.4560 (10), b=6.7110 (10), c=9.1820 (10), =110.600 (10), =101.100 (10), P-1, Z=2 for 1009 independent reflections, R1=6.98, wR=7.03. The structure consists of sheets made of edge-sharing [NiO₆] and [ZnO₅] polyhedra. In the title compound, Ni ions are forming dimers [Ni₂O₁₀] with short d_Ni__Niof 3.006 Å.

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Li_0.50Co_0.25TiO(PO₄) has been obtained by the conventional solid state reaction technique. Its crystal structure has been refined from X-ray powder diffraction data by the Rietveld method in P2₁/c space group (R_B=0.08, R_F=0.05, R_p=0.13 and R_wp=0.18). The monoclinic unit cell parameters are: a_m=6.400±0.001Å, b_m=7.279±0.001Å, c_m=7.385±0.001Å,β=90.36?±0.02°Z=4. The structure is formed by a three dimensional framework of TiO₆ octahedra and PO₄ tetrahedra. TiO₆ octahedra form -Ti-O-Ti-O- infinite chains parallel to the c axis. In these chains, very short Ti-O bonds (~1.68Å) and very long ones (~2.26Å) are alternating. The cobalt and lithium atoms occupy octahedral cavities which form infinite chains of edge-sharing octahedra running parallel to the a axis.

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Pb_0.5Ti₂(PO₄)₃ has been prepared from solutions of the corresponding elements. Its crystal structure has been determined in R3 space group, from X-ray powder diffraction data by Rietveld method. R_p=0,10, R_wp=0,13; R_B=0,06. The parameters of the equivalent hexagonal cell are a_h=8.298±0.004Å and c_h=22.70±0.06Å. The structure is formed by a 3D network of TiO₆ octahedra and PO₄ tetrahedra linked by corners. Pb²⁺ occupies half of the M1 site in an ordered manner. The Pb-O distance is 2.57Å. TiO₆ octahedra are slightly distorted with Ti-O distances of 1.85; 1.87, 1.95 and 2.00Å. PO₄ tetrahedra are normal, the P-O distances vary from 1.52 to 1.56; angles vary from 105 to 113°.

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Two new phosphates Fe_0.5TiO(PO₄) and Fe_0.5Ti₂(PO₄)₃ have been prepared and characterised by X-ray diffraction, Mössbauer spectroscopy and magnetic measurements. Fe_0.5TiO(PO₄) is isostructural to the oxyphosphate Ni_0.5TiO(PO₄) while Fe_0.5Ti₂(PO₄)₃ belongs to the Nasicon family. Their structures are formed by a 3D framework of TiO₆ octahedra and PO₄ tetrahedra linked by corners. Fe²⁺ ions occupy isolated octahedral cavities situated between two TiO₆ octahedra. The magnetic and Mössbauer parameters are typical of Fe²⁺ ions in octahedral sites with high spin configuration t_2g⁴e²_g.

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By means of EPR and optical spectroscopy were investigated phosphate glasses in the system xCaO-(100-x)P₂O₅, where 37≤x≤57, implanted with Ti⁺, Cr⁺, V⁺, Co⁺ and Mo⁺ (E=150keV, fluences F=2x10¹⁶÷5x10¹⁷cm^-2). The EPR spectra of samples co-implanted with V⁺and O⁺as well as Mo⁺and O⁺ were also studied. Some samples were co-implanted with ⁹⁵Mo⁺ and O⁺. EPR spectra were recorded at room temperature, 77K, in the range from 100 to 450K and at 4.2K The results are discussed together with data obtained earlier in our laboratory for phosphate glasses implanted with transition metals (TM). It is shown that the ions of transition metals Ti³⁺, V³⁺, V⁴⁺, Cr³⁺, Mn²⁺ Co²⁺, Cu²⁺, Mo⁵⁺ can be present in isolated states in implantation layers of phosphate glasses at a rather low fluences (≤5x10¹⁶ cm^-2). The ions in high valences forms (V⁴⁺, Mo⁵⁺) are formed only in the case of co-implantation with O⁺. The ions Ti³⁺, V⁴⁺, Mo⁵⁺ are in tetragonally compressed octahedral and Ion Cu²⁺ is in tetragonally elongated octahedron, i. e. tire in their the most typical environments. However, spectral parameters for these ions differ from those obtained for them in glasses of corresponding compositions melted, from the batch. The isolated ions Cr³⁺ and Co²⁺ are in octahedral coordination. At high fluences(≥10¹⁷cm^-2) some TM ions can form in implanted phosphate glasses compounds with O or PO groups (for example, antiferromagnetic crystals MnO, compounds with phase transition at 340K VO₂, ferromagnetic crystals CrO₂ with temperature Curie, Tc=390K, non-stoichiometric compound TixPO₄).

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Na₃MgTi(PO₄)₃ phosphate exists in both crystalline and vitreous forms. The glass-crystal transformation was investigated using DTA, XRD, Raman spectroscopy and ionic conductivity. The crystalline phase which belongs to the Nasicon type family structure, space group R3, contains isolated TiO₆ octahedra whereas the corresponding glass contains Ti-O-P and Ti-O-Ti linkages. The Mg²⁺ ions are located in the framework for the crystalline phase while in the glass they are in the modifying network.

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Continuous solid solutions were isolated within the system A^ICd_1-xM^I_xPO₄(A^I=Li, Na; M^II=Mn, Co) for 0≤x≤1. The steady decrease of the lattice parameters and unit cell volume within the solid solution domains was ascribed to the substitution of Cd²⁺ cations by smaller size M²⁺ ions (M=Mn, Co) as the composition progresses between x=0 and x=1. The investigation of the luminescence of Mn(II) has evidenced two large emission bands peaking at circa 576-580nm and 693-710nm for the analyzed compounds LiCd_1-xMn_xPO₄(0≤x≤0.7) under the excitation radiation with λ_exc=438nm. In this system, a small red shift seems to appear for both emission bands when a higher excitation energy is used (λ_exc=325nm). In the case of LiZn_1-xMn_xPO₄(0≤x≤0.2), only one luminescence band was recorded within a narrower range 550-556nm for λ_exc=488nm and at ca. 562nm under λ_exc=325nm. For the composition analysed in the system NaCd_1-xMn_xPO₄(x=0.05), the emission bands were found at 624.5nm and 616.4nm under excitation wavelengths equal to 488 and 325nm respectively. The luminescence of Mn²⁺ ions in all investigated phases was attributed to the same electronic transition ⁴T_1g(⁴G) ⁶A_1g(⁶S) which is very sensitive to the crystal filed strength as evidenced by Tanabe-Sugano energy diagram. Indeed as the solid solution progresses in the case of LiCd_1-xMn_xPO₄ for example (0≤x≤1), the size of the cavities hosting Mn²⁺ ions is consequently changing. As a matter of fact, the mean manganese-oxygen distance is expected to vary between the values corresponding to the mean bond length of the divalent cation in LiCdPO₄(<Cd-0>=2.298Å) and LiMnPO₄(<Mn-O>=2.201Å) respectively. The resulting change of the crystal field around Mn(II) may explain why the emission is observed in the green region for low values of x while it shifts to the red domain for compositions close to LiMnPO₄(x>0.5). The correlation between the modification of the wavelength of Mn²⁺ luminescence bands and the crystal field strength inherent to the variation of the chemical composition is therefore established. A model for the distribution of the divalent cations within the lattice along the solid solutions was also proposed.

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The gels and glasses of AlPO₄ and sodium aluminophosphate with composition of 40Na₂O-20Al₂O₃-40P₂O₅ are prepared through a novel sol-gel route based on the reaction of alun mum lactate with H₃PO₄ and NaH₂PO₄ in aqueous solution. The sol-gel chemistry was characterized by high-resolution solution NMR and solid state ²⁷Al and ³¹P MAS NMR, and ²⁷Al{³¹P} Rotational Echo Double Resonance (REDOR) techniques. Detailed NMR data confirm that the local structures, the distributions of sites and the degree of Al/P connectivity in the sol-gel derived glasses are essentially indistinguishable with those of the melt-cooled glasses.

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