Phosphate Rock Samples Research Articles

Characterization of the Tunisian Phosphate Rock from Metlaoui-Gafsa Basin and Bio-Leaching Assays

Soil contamination by heavy metals through the application of a phosphate fertilizer is a key issue for sustainable agriculture. Among contaminants, cadmium (Cd) is considered the most hazardous to human beings’ health and the surrounding environment. X-ray diffraction (XRD), combined with binocular mineralogical analysis and chemical analysis, was used to determine the C(I) and C(II) layers’ composition. In the C(II) (+71 µm)-size fraction, the presence of carbonate-fluorapatite, illite, and montmorillonite was revealed, whereas in the C(I) (−71 µm)-size fraction, carbonate-fluorapatite, calcite, quartz, sanidine, clinoptilolite, and taramovite were identified. The P2O5 and CaO contents were greater in the C(II) layer than that in the C(I) layer, whereas SiO2, MgO, CO2, Cd, Zn, and COrg were higher in the C(I) layer than that in the C(II) layer. The bioleaching of Cd from phosphate rock samples from the Kef Eddour deposit was investigated using three bacterial strains isolated from the local phosphate environment. A decrease in cell viability was noticed when the phosphate C(I) and C(II) samples showed toxicity in the samples. In addition, the isolated bacteria, which were initially moderately hydrophobic, changed to strongly hydrophobic. The use of the consortium (S1 + S2 + S3) was the most powerful combination to reduce the Cd content, which increased from 13.31% to 29.07% using S3 and the consortium (S1 + S2 + S3), respectively, when the C(II) (+71 µm)-size fraction sample was added to the medium. The same result was shown when the C(I) (−71 µm)-size fraction sample was used. The isolated strains could be used as a biological tool for bioleaching.

Development of a simple and fast ultrasound-assisted extraction method for iodine determination in phosphate rock and phosphogypsum by-product using titrimetric method

ABSTRACT Phosphate rocks, as well as their derivatives and by-products, are complex minerals that make elemental analysis very complicated. Iodine is commonly found in these matrices, and its concentration must be controlled. The present work describes the development of a novel rapid digestion protocol based on ultrasonic-assisted acid digestion for the determination of iodine in phosphate rock and phosphogybsum samples by Iodometric titration. The developed method occurs at low digestion temperature and uses a dilute nitric acid 5% (v/v) solution instead of concentrated acid. The investigated parameters influencing UAD, were completely optimised using experiments design methodology (DOE). Iodine recoveries from dilute nitric acid digestion without sonication were generally lower overall when compared to UAD results, illustrating the effect of ultrasound on iodine dissolution. This technique effectively addresses iodine volatilisation and sample losses problem encountered while using classical digestions. Method validation included: defining the detection and quantification limit of iodine using this method were about 2.2 and 8 mg.kg−1, respectively, and it's suitable for the proposed application. Moreover, the repeatability and reproducibility, expressed as RSD for phosphogybsum sample was 7%, 8.3% respectively, while for phosphate samples is tacked as the mean of relative standard deviation 3.4%, 3.8%. Additionally, accuracy of the method was assessed by analysing a certified reference material and the iodine concentration was found to be in good agreement with the indicative values for this CRM. Thus, the mean recoveries in fortified sample were between 96% and 107%.The developed method is fast, accurate, and it is applicable to the monitoring of iodine in the phosphate industries.

Examination of the parameters affecting of 222Rn emanation for some industrial and environmental samples using gamma-spectroscopy

The present work aims to radiologically characterize five samples (monazite, zircon, scale waste originating from petroleum production, black sands and phosphate rocks) from different industrial applications and environments in the Egyptian territory. The first section of the present work discusses the measurement and analysis of 226Ra, 232Th and 40K concentrations. Moreover, the assessment of the hazard indices is given in terms of radium equivalent (Raeq), external hazard index (Hex), internal hazard index (Hin), gamma-activity index (Iγ) and alpha-activity index (Iα). The second section deliberates the 222Rn gas emanated from the samples and studies the physical parameters affecting the emanation process. The results found that the monazite sample has the highest concentration of 226Ra, 232Th and 40K; however, it reached 54435, 442105 and 583 Bq.kg−1, respectively, between the studied samples. Furthermore, black sands and phosphate rock samples exhibit the lowest concentration of 226Ra, 232Th and 40K. Results also show that the radon emanation coefficients decrease while the density of materials increases.

Analysis of the solubility of phosphate rock from Aipe (Colombia) via formation of 2Na-EDTA complex

Phosphate rock (PR) is the main source of phosphorous used in fertilizers for Colombian soils. In many regions of Colombia, PR is applied directly to the soil, which affects eutrophication problems and phosphorus losses due to runoff, because to the low solubility of phosphorus in this georesource. In this article, phosphate rock samples from Colombia were treated with ethylenediamine tetra-acetic acid disodium salt dihydrate (2Na-EDTA) at different concentrations. PR obtained from the Media Luna Mine, located in Aipe, Huila (Colombia), was characterized using Infrared Spectroscopy, X-ray Diffraction and Scanning Electron Microscopy. Carbonate fluorapatite Ca9.74(PO4)5.45F2.05(CO3)0.53 (0.5%–61.5 %), hydroxyapatite - Ca5(PO4)3OH (26.6 %–84.0 %) and quartz- SiO2 (13.2 %) were the minerals found in the largest composition in the two samples of PR. The PR was crushed to powder (~125 μm) and it was treated with disodium EDTA dihydrate solutions at different concentrations [0.0025–0.1000 M]. Water-soluble phosphate was determined by UV–Vis spectrophotometry based on the ASTM -4500P method. The modified absolute solubility index (ASI*) was calculated for each EDTA treatment used in the phosphate rock, considering the total phosphorus solubilized in H2SO4 (40 % v/v) at 30 °C. The statistical analysis showed that there were significant differences between the treatments used, where (16.87 %) was presented highest ASI* for the treatment with 2Na-EDTA (0.353 M).

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.

SOLVENTES EUTÉTICOS NATURAIS PROFUNDOS (NADES) NO PREPARO DE AMOSTRAS DE ROCHA FOSFÁTICA E SUPLEMENTO MINERAL PARA DETERMINAÇÃO ELEMENTAR POR TÉCNICAS DE PLASMA

NATURAL DEEP EUTECTIC SOLVENTS (NADES) IN SAMPLE PREPARATION OF PHOSPHATE ROCK AND MINERAL SUPPLEMENT FOR ELEMENTARY DETERMINATION BY PLASMA-BASED TECHNIQUES. Natural deep eutectic solvents (NADES) based on xylitol, citric acid, and malic acid were synthesized and used in ultrasound-assisted extraction (UAE) and heating-bath extraction of phosphate rock and mineral supplement samples. Arsenic, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P and Zn were determined by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES). The results showed the NADES as promising solvents for extraction of inorganic matrices compared to reference values and concentrations obtained using microwave-assisted acid digestion (MW-AD). Significant differences were observed for some elements, suggesting different chemical interactions between the synthesized NADES and each monitored element. For analytes extraction of phosphate rock, UAE presented the best results for As, Cr and P. Zinc was extracted with UAE and heating bath. Concerning mineral supplement, no significant differences were observed for Ca (UAE), Cd (UAE and heating bath), K (UAE and heating bath), Mn (UAE and heating bath), Na (UAE and heating bath), and P (UAE and heating bath). The NADES is a greener and a potentially alternative for the sample preparation compared to the official methods of analysis, can being used as selective extractor solvent in conventional sample preparation methods.

Thermal Beneficiation of Sra Ouertane (Tunisia) Low-Grade Phosphate Rock

Low-grade phosphate rock from Sra Ouertane (Tunisia) was beneficiated using a thermal treatment consisting of calcination, quenching, and disliming. Untreated phosphate rock samples (group 1), calcined phosphate rock samples (group 2), as well as calcined, quenched, and dislimed (group 3) phosphate rock samples, were investigated using inductively-coupled plasma atomic emission spectroscopy (ICP-AES), inductively-coupled plasma mass spectrometry (ICP-MS), thermogravimetric analysis (TGA), and X-ray powder diffraction (XRD). Besides, the particle size distribution of the aforementioned three groups was determined. The proposed thermal treatment successfully increased the P2O5 content of the untreated phosphate rock from 20.01 wt% (group 1) to 24.24 wt% (group 2) after calcination and, finally, 27.24 wt% (group 3) after calcination, quenching, and disliming. It was further found that the concentration of relevant accompanying rare earth elements (Ce, La, Nd, Pr, Sm, and Y) was increased and that the concentration of Cd could be significantly reduced from 30 mg/kg to 14 mg/kg with the proposed treatment. The resulting phosphate concentrate showed relatively high concentrations in metal oxides: Ʃ MgO, Fe2O3, Al2O3 = 3.63 wt% and silica (9.81 wt%) so that it did not meet the merchant grade specifications of a minimum P2O5 content of 30 wt% yet. Removal of these elements could be achieved using additional appropriate separation techniques.

Radioactivity and Radiation Hazard Indices Assessment for Phosphate Rock Samples from Al-Jalamid, Turaif, Umm Wu’al, and As-Sanam, Saudi Arabia

In this study, the activity concentration of 235U, 40K, 238U, 226Ra, and 232Th in phosphate rock found in the Kingdom of Saudi Arabia has been measured by gamma-ray spectrometry. Phosphate is extracted from the northern region in Saudi Arabia and widely used in agriculture as fertilizers as well as in the chemical industry. The average activity concentration of 235U, 238U, 226Ra, 232Th, and 40K has been measured as (10.34 ± 1.49 Bq kg−1, 260.99 ± 19.68 Bq kg−1, 242.33 ± 2.74 Bq kg−1, 3.42 ± 0.94 Bq kg−1, and 47.50 ± 3.03 Bq kg−1) for Al-Jalamid phosphate rock ores, respectively; (46.10 ± 2.61 Bq kg−1, 1028.31 ± 36.88 Bq kg−1, 989.98 ± 6.41 Bq kg−1, 13.75 ± 1.68 Bq kg−1, and 51.93 ± 3.82 Bq kg−1) for Turaif phosphate rock ores, respectively; (63.60 ± 3.33 Bq kg−1, 1353.25 ± 41.58 Bq kg−1, 1304.29 ± 7.70 Bq kg−1, 13.45 ± 1.64 Bq kg−1, and 40.26 ± 3.67 Bq kg−1) for Umm Wu’al phosphate rock ores, respectively; and (13.83 ± 1.59 Bq kg−1, 318.72 ± 21.78 Bq kg−1, 350.50 ± 3.14 Bq kg−1, 5.01 ± 1.13 Bq kg−1, and 42.15 ± 3.02 Bq kg−1) for As-Sanam phosphate mines, respectively. The radiological parameters (gamma index, absorbed dose, outdoor and indoor annual effective dose, and total excess lifetime cancer risk (ELCR)) have also been calculated to assess the health hazards. The radiation indices, effective dose, and ELCR have been found high in all samples corresponding to International Commission on Radiological Protection (ICRP) safety limits, which reflects a radiological health risk for workers and population. The X-ray diffraction (XRD) analysis confirms the concentration of dominant elements like fluorapatite (Ca5(PO4)3F), dolomite (CaMg (CO3)2), and minor traces of quartz (SiO2) and calcite (CaCO3). The elemental concentration of CaO, Al2O3, P2O5, SiO2, MgO Al2O3, and Fe2O3 has been measured by X-ray fluorescence (XRF) technique.

Potential radiological impact of the phosphate industry in South Africa on the public and the environment (Paper 1)

Phosphate rock is mined on a large scale as a source material for fertilizers and other phosphorous containing products, such as phosphoric acid and gypsum. The potential problem of high concentrations of naturally occurring radionuclides in the phosphate industry has been recognized for many years. The industry is responsible for the production of millions of tons of phosphogypsum waste, which is usually stockpiled and might impact the surrounding environment. The presented study aims to assess the natural radioactivity concentrations in raw and waste sub-products from phosphate mining and fertilizer production in South Africa and determine the potential radiological risk associated with the industry.Activity concentrations of 238U, 226Ra and 232Th in phosphate rock, phosphogypsum, tailings, fertilizer, soil and sediment were found to be similar to values reported in previous studies conducted in South Africa. Concentrations of the 232Th decay series were higher than those of the 238U series in rock and ore. The low concentrations of 238U and 226Ra in rock and ore, compared to other countries, makes it more suitable to be used for fertilizer production, and therefore increases the demand for export of rock phosphate and fertilizer from South Africa. 228Ra concentrations in phosphogypsum were higher than 226Ra. The activity of 228Ra was also enriched compared to 232Th, with a ratio of 0.45–19.8. Similar equilibria as described in literature were observed, with almost all the 228Ra and 226Ra present in the phosphate rock observed in the phosphogypsum. Only a low percentage of 232Th present in the original rock remained in the phosphogypsum, with more than 60% present in the fertilizer.The activity concentrations of all nuclides in the analysed samples from the phosphate industry were less than the 1000 Bq kg−1 exclusion value proposed internationally for regulation of NORM. With the exception of phosphate rock samples, concentrations in all solids were lower than the 500 Bq kg−1 limit proposed by the National Nuclear Regulator in South Africa. The obtained values of Raeq for all phosphogypsum, tailings and soil samples were less than the recommended limit of 370 Bq kg−1.The gamma index for the majority of samples was less than 0.5. The index exceeded the limit of unity only for phosphate rock and fertilizer samples, indicating some radiological risk to people living in the vicinity of the industry. The results suggested that members of the public were unlikely to receive any significant dose from the use of phosphate rocks and fertilizers, with an annual effective dose of less than 0.5 mSv.a−1. The highest external dose of 0.45 mSv a−1 is expected from phosphate rock.The suitability of use of phosphogypsum as building material was evaluated. Based on the calculated gamma index [Iγ = 0.52 ± 0.14] use of phosphogypsum as building material is permitted.

Dynamics of metals in backfill of a phosphate mine of guiyang, China using a three-step sequential extraction technique

Phosphate rock in Guiyang (Southwest of China) is used for the phosphate production, and hence generating a by-product phosphogypsum (PG). From 2007, part of the PG was used as main raw material for cemented backfill. The main objective of this paper is to investigate the geochemical evolution of metals before and after the PG inclusion into the backfill matrix. A sequential extraction procedure was selected to determine the chemical speciation of metals in phosphate rock, PG, binder and field backfill samples. Dynamics of metals going from phosphate rock and PG to backfill have been evaluated. The results showed that almost all the metals in the PG and binder had been effectively transferred to the backfill. Furthermore, compared to metals taken out along with phosphate rock exploitation, PG-based cemented backfill might bring some metals back but with only little metals in mobile fraction. Additionally, in order to determine the long-term behavior of metals in PG-based cemented backfill, the field samples which were backfilled from 2007 to 2016 were collected and analyzed. The results showed that total amounts of metals in backfill were all within similar range, indicating that the cemented PG backfill could be an effective method to solidify/stabilize metals in PG. Nevertheless, Due to the high water-soluble fractions detected, the concentrations of As, Mn and Zn should be continuously monitored.

Addition of low-grade phosphate rock for improvement of soil fertility on plant models: A preliminary case study

To sustain food production in the course of time and for efficient utilization of available resources, it is essential to approach improved methodologies and techniques for enhancing crop productivity. Commercial agricultural production has achieved this through the external application of synthetic inorganic fertilizers which has some detrimental effects on the soil structure, composition, microflora and additional characteristic properties of soil. The mining and industrial waste is an unwanted by-product of mining. Reusing and recycling of these wastes is possible therefore recovery and recycling is the most excellent environmental resolution to save raw resources and to diminish the number of industrialized waste materials produced, and also control the contamination of the environment. In the present study, an attempt has been made to utilize low-grade phosphate rock as a fertilizer and its effects on soil fertility. The raw phosphate rock samples are subjected to physicochemical test followed by elemental analysis by EDXRF (Energy Dispersive X-ray Fluorescence). The tests confirmed that it is possible to use this raw phosphate rock as fertilizer for plant growth in a simple process. Different soil and plant parameters were measured. Data on pot experiment revealed higher plant growth is in PR amended soil than normal soil. The greatest positive effect on growth was recorded in the treatments that received phosphate rock (8g) per kg of soil. Thus, observations indicated that direct application of this PR could be an alternative, promising technology for simultaneous waste minimization, waste utilization, and improved resource-use efficiency.

Application of Gettering Process on the Improvement of the Structural and Mineralogical Properties of Tunisian Phosphate Rock

The present study deals with the effects of gettering process on the structural and mineralogical composition of Tunisian phosphate rock. The treated samples were characterized to investigate the variation of physical structure and chemical composition as compared to the reference phosphate rock. The quantitative analysis of the impurities concentration before and after gettering treatment using energy-dispersive (EDX) reveals a significant reduction of impurity concentration (more than 75%) such as Al, Si, S, Na, and Mg. Scanning electron microscopy (SEM) shows that gettering process promoted structural alterations of phosphate rock sample due to fusion of impurities. The XRD patterns show that the chief mineral constituent of treated sample is only fluorapatite, while those in the reference ore were calcite, dolomite, quartz and carbonate-fluorapatite. FT-IR characterization show a disappearance of the bands related to calcite at 714 cm-1 as well as B carbonate situated at 1430 cm-1, 1458 cm-1 after gettering treatment. This result is in good correlation with Raman analysis.

A thorough investigation of the uranium concentration in phosphate mines: a case study of Minjingu phosphate mine, Arusha, United Republic of Tanzania

Using high resolution gamma ray spectrometry, the terrestrial radionuclides from all phosphate rock samples were measured and results are presented. From the measured gamma ray spectra, activity concentrations were determined for 226Ra/238U (range from 122.5±6.9 to 8060±806 Bq kg−1), 232Th (range from 13.2±0.8 to 1201.3±77.3 Bq kg−1), 40K (range from 12.9±1.3 to 1827.6±93.9 Bq kg−1) and 137Cs (range from 0.5±0.017 to 70.58±1.25 Bq kg−1) with mean of 1832.32±00, 447.62±00, 399.46±00 and 22.98±0.43 Bq kg−1 respectively. Radium equivalent activity ranges from 219.27±00 to 9127.07±00 Bq kg−1 with mean of 2433.56±00 Bq kg−1. The total absorbed dose estimated at 1 metre above the ground varies from 102.1 to 3967.8 nGyh−1 with an average of 1055.9 nGy h−1. Investigation of uranium recorded a peak of 650±65ppm, this suggests the existing U concentration is over three times greater than economically viable and production of a cleaner fertiliser is favourable.

Radiological measurement of phosphate rock and phosphogypsum from fertilizer industries in India

Phosphate deposits are generally characterized by high levels of natural radionuclide concentrations. Natural radionuclides from the uranium and thorium series were measured, using high-resolution gamma-spectrometry in phosphate rock and phosphogypsum samples from the phosphate fertilizer industry in India. Equilibrium was found to be disrupted during the chemical processing of phosphate rock with 83 % of the 226Ra and only 5 % of 238U fractionating to phosphogypsum. Activity concentrations of 238U and 226Ra in phosphogypsum produced from various fertilizer industries of India showed levels < 1,000 Bq kg−1 and pose no restriction for use in building/construction material.

English

Phosphate rock samples collected from the phosphate bearing formations of Sokoto State, Northwest Nigeria were assessed for their radiological contents by gamma spectrometric technique (sodium iodide (NaI (Tl) detector). The mean activity concentrations of 226Ra, 232Th and 40K in all the studied samples were 720.1&plusmn;4.2 Bqkg-1, 33.5&plusmn;1.4 Bqkg-1, and 315.3&plusmn;6.7 Bqkg-1 respectively. Contributions from radium contents to the overall radionuclide activity concentrations were quite significant. The calculated mean value of the absorbed dose rate was found to be 3.6 times the maximum value for the world background level, which shows the severity of radiation risk the public is exposed to in the study areas. The computed values for radiation hazard indices were above the world&rsquo;s proposed safety limits by UNSCEAR, which place the study areas among high background radiation zones. Some restrictive measures and precautionary actions are therefore obligatory for the local farmers and the general public from the view point of radiation protection. &nbsp; Key words: Natural radioactivity, Sokoto, phosphate rock, radiation hazard, NaI (Tl) detector, radiation dose.

Radiological impacts of natural radioactivity in phosphate rocks from El-Sibaiya and Red Sea coast mines, Egypt

Using gamma spectrometry, the activity concentrations of natural radionuclides (226Ra, 232Th and 40K) were measured in phosphate rock samples collected from phosphate mines located in El-Sibaiya (Nile valley) and Red Sea coast, Egypt. The average activity concentrations of 226Ra, 232Th and 40K (Bqkg−1) in phosphate rocks were 512 ± 26, 41 ± 2 and 428 ± 21 Bq kg−1 for El-Sibaiya and 422 ± 21, 37 ± 2 and 324 ± 16 Bq kg−1 Red Sea coast, respectively. The radiological hazards to the occupational workers and public caused by γ-radiation have been determined.

Study on the Rare Earth Containing Phosphate Rock in Guizhou and the Way to Concentrate Phosphate and Rare Earth Metal Thereof

Guizhou province is one of the main phosphate resources base in China, characterized with the co-existence of rare earth in the phosphate rock. In this work, the phosphate rock samples in Zhijin County, Guizhou province have been collected and analyzed using ICP, X-Ray diffraction, Scanning microscope, Infrared spectra and X-ray photoelectron spectroscope. It is found that the total content of rare earth elements in the phosphate rock is about 0.1 wt%, amongst which Y, La, Ce, Pr, Nd and Sm are the main rare-earth components and co-sit the lattice of the apatite. The phosphate content in the as-collected rock is more than 20 wt%, and impurities such as quartz, calcite and clay are also present. The raw phosphate rock physically was treated with flotation to remove the impurities such as quartz and calcite; a refined phosphate with rare earth elements of more than 0.1 wt%. The refined phosphate rock is then treated with excessive H3PO4 to dissolve the apatite; the residue from the dissolution gives an earth enriched precipitation, which contains up to 2 wt% rare earth elements. Compared to the conventional way to use H2SO4 to extract phosphate, the treatment of the refined phosphate with phosphoric acid leads to significantly improved rare earth oxide extraction.

Development of X-ray fluorescence technique for the uranium determination in mongolian coal, coal ash, and phosphate ore

The results of the determination of uranium in Mongolian brown coal, coal ash, phosphate rock, and technological samples by X-ray fluorescence ( XRF) spectrometry are presented. Technological samples were produced from phosphates by chemical treatment. Powder geological samples and Certified Reference Materials ( CRMs) were pressed as tablets. For chosen conditions of the sample preparation procedure analytical figures of merit were carefully studied, as exemplified by the rock and ura nium ore Reference Materials. The variance of the total uncertainty is 2 % for uranium in the analyzed samples, and one is 7 % in the rock CRMs. The estimated values of the uranium detection limit for the CRMs are within the interval from 1 to 3 ppm. For the correction of the matrix effects the background standard method was used. Values of the uranium contents in the studied samples vary within the interval from 3.0 to 35.0 ppm. The comparison of the wavelength dispersive (WD) XRF results with the energy dispersive (ED) XRF results and the neutron activation analysis (NAA) was performed. It is demonstrated that the WDXRF have satisfactorily agreed with the EDXRF results and the NAA within the limits of the uncertainty. It is shown that the values of the relative discrepancies between the WDXRF and EDXRF results are in the range of 2.0-18.0 %, and between the WDXRF and the NAA results are in the range of 2.0-20.0 %. These values are less than 30 %, yielding the third category of the precision of the miner

Separation and flame atomic absorption spectrometric determination of total chromium and chromium (III) in phosphate rock used for production of fertilizer

Due to the commercial value of phosphate rock (PR) as a fertilizer precursor, it is necessary to investigate its heavy metals content. Chromium (Cr) may present as Cr(III) or Cr(VI) in PR; but quantitative differentiation between them is not an easy task. This is due to possible interconversion of Cr species during the digestion/leaching process. In this work, ultrasound digestion (USD) of PR was optimized (300mg PR, 4.0mL of 4.0molL−1 nitric acid, 15min sonication) for the sake of leaching Cr species prior to their determination by flame atomic absorption spectroscopy. Using multi-walled carbon nanotube (MWCNT) as adsorbent, solid phase extraction (SPE) was used to separate Cr(III) from the digestate at pH 9, while total Cr was estimated after reducing Cr(VI) into Cr(III). The optimum USD/SPE method gave LOQ and LOD of Cr(III) of 0.96mgkg−1 and 0.288mgkg−1, respectively. The method sensitivity was 1.44×10−3AUkgmg−1 within the studied Cr concentration range (5–400mgkg−1). The USD/SPE method was validated by analyzing lake sediments LKSD-4 certified reference material, and by comparison with classical digestion method (CD). Application of USD/SPE on Jordanian PR samples gave total Cr rang 29.1–122.0mgkg−1 (±1.4–6.3), while Cr(III) ranged between 23.8 and 101.7mgkg−1 (±1.3–5.5). AFPC Rock Check Program samples gave total Cr range 238.9–394.7mgkg−1 (±11.5–24.1), while Cr(III) ranged between 202.4 and 335.8mgkg−1 (±11.4–18.3). These results were very close to the results obtained by the CD method.

Elemental Analysis of Egyption Phosphate Fertilizer Components Samples by TGA, DTA and IR Methodes

The accumulation of certain elements in vitally important media such as water, soil, and food is undesirable from the medical point of view. It is clear that the fertilizers vary widely in their heavy metals and uranium content in the phosphate fertilizer and its components collected from Abu-Zaabaland Abu-Tarturfertilizers and chemical industries in egypt and are elementally analyzed. The aim of thisstudy was to determine the concentration of Cd, Cu, Cr, Ni, Pb, Zn (environmental pollutants i.e. toxicelements), and Co, K, Mg, Mn, Na (common elements) in phosphate rocks used for production of fertilizer.Thedata showed major concentrations of 17 elements (P , S , Ca ,Ti , V , Mn , Fe, Zn, As, Sr , Y andZr) and rare-earth element ( Rh, Pr , Gd , Tb and Tm ).The results for the input raw material rock phosphate and the output product as final fertilizerarepresentedanddiscussed.Phosphate rock belongs mainly to sedimentary, slightly to igneous, and negligibly to metamorphic rocks. It isused for the production of phosphorous based fertilizers, acids, detergents and many products of commonuse. The rock is mainly composed of phosphorous and minutely of many other elements. Phosphate Rock samples of local origin were collected from the geological rock formations around the New Valley Governorate were obtained from theAbu-Tartur fertilizer factories. Analysis of phosphate rock for all the elements of interest was carried out with IR Spectroscopy analysis Tanta University Model FT.IR Tensor 27BruKer (5000 cm -1 – 200 cm -1 ). The results showed that heavy metalcontent was lower in Abu-Tartur phosphate than that in imported rock and were below the safe limits with theexception of lead whose concentration was found to be higher in local phosphate deposits than that inimported rock samples. Phosphate rock is a source of heavy metal pollution of air, soil, water, food chain etc,therefore requires removal of heavy metals (HMs) from the rock prior to its use.This work has shown that compounds with phosphatestructures can