Investigation of Metal and Nonmetal Ion Migration through an Inactive Phosphogypsum Stack

Jr., O. C. Carter,; Smith, C. W.; Scheiner, Bernard J.

doi:10.21000/jasmr93010175

Cited by 7 publications

(8 citation statements)

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“…Another matter of concern is the leachability of hazardous elements from PG and thus the contamination of groundwater underlying PG stacks (May and Sweeney, 1982;May and Sweeney, 1983;Carter and Scheiner, 1992;Berish, 1990). Since PG waste is generally transported and disposed as an aqueous slurry, PG piles can be affected by tidal variations and dissolution/leaching of the elements naturally present in the PG can occur.…”

Section: Water and Soil Contaminationsmentioning

confidence: 99%

Environmental impact and management of phosphogypsum

Tayibi¹,

Choura

López³

et al. 2009

Journal of Environmental Management

706

254

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The production of phosphoric acid from natural phosphate rock by means of the wet process gives rise to an industrial by-product named phosphogypsum (PG). About 5 tonnes of PG are generated per tonne of phosphoric acid production, and worldwide PG generation is estimated to be around 100-280 Mt per year. Most of this by-product is disposed of without any treatment, usually by dumping in large stockpiles. These are generally located in coastal areas close to phosphoric acid plants, where they occupy large land areas and cause serious environmental damage. PG is mainly composed of gypsum but also contains a high level of impurities such as phosphates, fluorides and sulphates, naturally occurring radionuclides, heavy metals, and other trace elements. All of this adds up to a negative environmental impact and many restrictions on PG applications. Up to 15% of world PG production is used to make building materials, as a soil amendment and as a set controller in the manufacture of Portland cement; uses that have been banned in most countries. The USEPA has classified PG as a "Technologically Enhanced Naturally Occurring Radioactive Material" (TENORM).This work reviews the different environmental impacts associated with PG storage and disposal. The methods described in the literature to minimise the negative effects of this waste are classified by treatment type, i.e. physical, chemical, thermal, etc., and different suggested applications for PG are detailed.

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Section: Water and Soil Contaminationsmentioning

confidence: 99%

Environmental impact and management of phosphogypsum

Tayibi¹,

Choura

López³

et al. 2009

Journal of Environmental Management

706

254

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“…However, the half-life if 226 Ra (1620 years) is considered to be the major long-term source of radioactivity in PG, prevent the use of this by-product for soil amendment or other purposes (EPA, 1999;El Mrabet et al, 2005;Lysandrou and Pashalidis, 2008;Socrates et al 2008), and may pose a potential hazard to human health (SENES, 1987;Papastefanou et al, 2006). Previous studies have been conducted on leaching processes of 226 Ra, in order to evaluate the impact of PG stockpiles on the surrounding environment (May and Sweeney, 1984;Fourati and Faludi, 1988;Berish, 1990;Carter and Scheiner, 1992;Burnett and Elzerman, 2001). Haridasan et al (2002) examined the leachability of 226 Ra in distilled water and rainwater under different leaching conditions such as contact time, solid/liquid ratio and simulating natural conditions.…”

Section: Introductionmentioning

confidence: 99%

Distribution and mode of occurrence of radionuclides in phosphogypsum derived from Aqaba and Eshidiya Fertilizer Industry, South Jordan

Al-Hwaiti

Zielinski²,

Bundham³

et al. 2010

Chin. J. Geochem.

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Phosphogypsum (PG) is a by-product of the chemical reaction called the "wet process" whereby sulphuric acid reacts with phosphate rock (PR) to produce phosphoric acid, needed for fertilizer production. Through the wet process, some impurities naturally present in the PR become incorporated in PG, including U decay-series radionuclides, are the main important concern which could have an effect on the surrounding environment and prevent its safe utilization. In order to determine the distribution and bioavailability of radionuclides to the surrounding environment, we used a sequential leaching of PG samples from Aqaba and Eshidiya fertilizer industry. The results showed that the percentages of 226 Ra and 210 Pb in PG are over those in the corresponding phosphate rocks (PG/PR), where 85% of the 226 Ra and 85% of the 210 Pb fractionate to PG. The sequential extraction results exhibited that most of 226 Ra and 210 Pb are bound in the residual phase (non-CaSO 4 ) fraction ranging from 45%-65% and 55%-75%, respectively, whereas only 10%-15% and 10%-20% respectively of these radionuclides are distributed in the most labile fraction. The results obtained from this study showed that radionuclides are not incorporated with gypsum itself and may not form a threat to the surrounding environment.

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“…During the wet chemical treatment with H 2 SO 4 of the phosphate ores and particularly the fluoro-apatite, for the production of phosphoric acid (H 3 PO 4 ), high concentrations of impurities including rare earth elements (REEs), are released and follow either the leach solution or the phosphogypsum by-product [7].…”

Section: Introductionmentioning

confidence: 99%

“…In Table 1, we report the contents of the impurities in phosphogypsum precipitated from wet sulphuric digestion of phosphate ore [7].…”

Section: Introductionmentioning

confidence: 99%

The effect of fluoride and silicate ions on the coprecipitation of gadolinium with calcium in phosphoric and sulpho-phosphoric media

Bouhlassa¹,

Salhamen²

2012

Radiochimica Acta

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Gadolinium / Coprecipitation / Phosphoric and sulpho-phosphoric media / Fluoride / SilicateSummary. This work was carried out with the aim to establish the effect of some impurities on the coprecipitation of gadolinium with calcium phosphate and gypsum. The tests were performed using the radioactive tracer technique to monitor the fate of gadolinium in various phosphoric and sulpho-phosphoric media containing fluoride and silicate ions as impurities. In 10 −2 to 10 −1 M NH 4 H 2 PO 4 solution, the Gd(III) at a concentration of 10 −4 M is almost entirely precipitated as amorphous phosphate. However, the presence of H 2 SO 4 at C H 2 SO 4 ≥ 0.1 M, reduces the coprecipitation to less than 8 at. %, on average. The fluoride ions in solution, even at C HF ≤ 0.1 M, induce a reduction of coprecipitation of 10 to 30% according to HF concentration. In the media containing 10 −2 to 10 −1 M NH 4 H 2 PO 4 and 10 −1 M H 2 SO 4 , the effect of HF is almost negligible in the absence of Si(IV); nevertheless, the presence of fluorosilicate in solution may contribute to the enhancement of the coprecipitation of the REE. The sulphuric acid (0.1 M) in phosphoric media (0.74 ≤ C H 3 PO 4 ≤ 4.44 M), leads to a significant coprecipitation of the REE (1.3 ± 0.2 ≤ D Gd ≤ 3.1 ± 0.5), whilst the addition of HF (0.1 M) to these media enhances the solubility of the REE ( D Gd = 0.06 ± 0.01).XRD, IR spectroscopy and elemental analyses of the solid phases in conjunction with the variation of the distribution coefficient D indicate that the coprecipitation of the REE is likely controlled by heterovalent substitution of REE in gypsum and its precipitation as phosphate or fluorosilicate.

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Investigation of Metal and Nonmetal Ion Migration through an Inactive Phosphogypsum Stack

Cited by 7 publications

References 0 publications

Environmental impact and management of phosphogypsum

Environmental impact and management of phosphogypsum

Distribution and mode of occurrence of radionuclides in phosphogypsum derived from Aqaba and Eshidiya Fertilizer Industry, South Jordan

The effect of fluoride and silicate ions on the coprecipitation of gadolinium with calcium in phosphoric and sulpho-phosphoric media

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