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1

The Assessment of Heavy Metals and Natural Radioactivity in the Phosphate Tailings at Minjingu Mines in Tanzania

Mdachi Daniel D., Rugaika Anita M., Machunda Revocatus L.

Journal of Ecological Engineering

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2024

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Vol. 25, nr 1

269--277

EN

Extraction and processing of the phosphate rocks has produced a massive amount of waste and posed a significant environmental concern. The majority of wastes generated in the fertiliser industry are overburden or waste rocks from mining, and phosphate tailings (PTs) or phosphogyp-sum from the beneficiation process. Phosphate rock mining and beneficiation expose heavy metals and radionuclides into the environment, which are harmful to living things. The purpose of this study was to determine the concentration levels of heavy metals and radionuclides activity in the phosphate tailings at Minjingu mines in northen of Tanzania. Heavy metals content and radionu-clide activity concentration were determined using energy dispersive X-ray fluoresence spectroscopy (ED-XRF) and high pure garmin energy detector (HPGe), respectively. The concentration of heavy metals investigated ranges: Cu – 12.9–27.3 mg∙kg-1, Fe – 7944.2–19052.2) mg∙kg-1, Mn – 410.9–474) mg∙kg-1, Ni – 1.9–13.2) mg∙kg-1, Al – 3597–13129.2) mg∙kg-1, Zn – 195.2–281.7) mg∙kg-1, Pb – 0.7–4.5) mg∙kg-1 and As – 2.7–11.3) mg∙kg-1. The result revealed that, the concentration level of heavy metals (Cu, Fe, Ni, As, and Pb) are below the permissible level while concentration level for Zn has high concentration compared to permissible level limit. However, the activity concentration of radionuclides 226Ra, 232Th and 40K were ranging from 311 to 7,606 Bqkg-1, 207 to 654 Bqkg-1 and 131 to 762 Bqkg-1, respectively. The reported results of activity concentration of radionuclides are found to be higher compared to the recommended world value. The study results will be used as a guide for decision making in addressing problems observed in phosphate tailings, including radiation safety standards for workers and environmental systems in phosphate mines.

2

Selective depression of Escherichia coli on flotation of collophanite and dolomite

Li JiaXin, Nie GuangHua, Jiang Ying, Luo GuoJv, Li Jie

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 4

art. no. 150604

EN

The phosphate rock flotatio n test was carried out using Escherichia coli E. coli ) as a depressant of dolomite. The results showed that E. coli had a great selective depression on dolomite during flotation. With E. coli as a depressant of dolomite, a useful beneficiation index of phosphorus concentrate with P2O5 grade of more than 30% and MgO content less than 1.2% can be obtained by closed circuit of one stage roughing and one stage cleaning. Furthermore, the depression mechanism of E. coli was studied by ad sorption experiments, infrared spectrum, and zeta potential. This study shows that the adsorption ability of E. coli onto dolomite is stronger than that of collophanite. When the pH is greater than 6, E. coli are chemically adsorbed on the surface of the c ollophanite and dolomite,which also increases the negative charge on the surface of the two minerals. The selective adsorption of E. coli cells to dolomite was best when the pH value is about 7.8.

3

Influence of measuring process properties on phosphate rock slurry rheology based on Brookfield method

Chen Aoao, Zhang Qin

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 6

art. no. 156202

EN

This research aims to explore how the flotation process conditions influence the rheological properties of phosphate rock slurry. The apparent viscosity of phosphate rock slurry was measured by Brookfield DVNext rheometer. Different mineral types, grinding time, slurry mass concentration and reagent systems were adopted to study the viscosity behavior of phosphate rock slurry. The results showed that under the same conditions, the apparent viscosity of apatite and dolomite slurry was basically the same, and the apparent viscosity of the slurry after mixing the two minerals was basically the same as that of single mineral. For the same slurry concentration, the mineral particle size had a significant effect on the rheological behavior of the slurry, and its apparent viscosity increased exponentially with the decrease of particle size. In addition, phosphate rock slurry showed shear thickening fluids characteristics when the slurry concentration is 20%-40%, but changed to pseudoplastic fluid at high concentration (60%). Sulfuric acid as pH regulator and inhibitor had little effect on the rheology of slurry; when GJBW and NaOL were added as collectors, the rheology of slurry changed, and the effect of GJBW was more obvious.

4

Effect of phosphate quality on foam generation during the phosphoric acid production process

Anouar Islaam, Jouraiphy Rim, Essallaki Hicham, Mazouz Hamid, Yousfi Samia, Boulif Rachid, Essaid Bilal, Bouamrani Mouna L.

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 2

48--57

EN

The presence of organics materials in phosphate ores generates foam during the manufacture of phosphoric acid, thus affecting the production performance and the quality of the products. Today, in the phosphate industry defoamers are used to reduce the negative impact of foam phosphoric production. In the present work, we focused on root cause evaluation for foam generation during the phosphoric acid production process, we evaluated the effect of phosphate rock quality in terms of organic carbon (OC) and carbonate content, on foam generation using a laboratory protocol for foaming ability evaluation. The results show that there is a relationship between the volume of the foam generated and the values of those impurities, while the volume of foam generated is higher when the concentration of OC and Carbonate is high. In our work, we confirm that the foaming ability of the phosphate rock can be avoided if the concentration of organic carbon less than 0.1% and less than 3% for carbonate.

5

Wpływ różnych zawartości jonów żelaza i glinu na proces filtracji ekstrakcyjnego kwasu fosforowego

Rolewicz Maciej, Musielska Urszula, Hoffmann Józef

Proceedings of ECOpole

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2019

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Vol. 13, No. 1-2

163--169

PL

W procesie otrzymywania kwasu fosforowego filtracja oddziela produkt, którym jest roztwór kwasu fosforowego, od produktu ubocznego, który zawiera głównie siarczan wapnia (fosfogips). Filtracja jest kluczową operacją w tym procesie, ponieważ od jej wydajności uzależniony jest skład fosfogipsu, który kierowany jest do składowania na hałdzie, oraz wydajność całego procesu otrzymywania kwasu fosforowego, co bezpośrednio przekłada się na ekonomikę prowadzenia procesu. W pracy przedstawiono wyniki badań wpływu różnych zawartości jonów żelaza oraz glinu na szybkość oraz czas filtracji poreakcyjnej pulpy otrzymanej w wyniku rozkładu fosforytu kwasem siarkowym. Proces filtracji prowadzony był przy różnicy ciśnień wynoszącej 55 i 75 kPa. Następnie określono maksymalną szybkość procesu filtracji oraz stałe filtracji K i C za pomocą odpowiednich równań.

EN

In the process of obtaining phosphoric acid, the filtration separates the product, which is a solution of phosphoric acid from a by-product, which contains mainly calcium sulphate (phosphogypsum). Filtration is a key operation in this process because the composition of phosphogypsum, which is directed to storage on the heap, and the efficiency of the entire process of obtaining phosphoric acid, which is directly related to the economics of the process, depends on its efficiency. The paper presents results of investigations on the influence of various contents of iron and aluminum ions on the rate and time of filtration of the post-reaction pulp obtained as a result of decomposition of phosphate rock by sulphuric acid. The filtration process was carried out at a pressure difference of 55 and 75 kPa. Then, the maximum filtration process speed and the filtration constants K and C were determined by means of appropriate equations.

6

Zwiększenie efektywności surowców fosforytowych poprzez dodatek siarki. Cz. 4, Wpływ dodatku siarki na zawartość mikroelementów w roślinach

Stanisławska-Glubiak E., Korzeniowska J., Hoffmann J.

Przemysł Chemiczny

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2012

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T. 91, nr 5

1006-1009

PL

Nawozy zawierające siarkę na skutek obniżania odczynu gleby mogą powodować zwiększone pobranie przez rośliny niektórych pierwiastków, zwłaszcza metali. Celem pracy było zbadanie, czy dodatki siarki w nawozach fosforytowo-siarkowych mogą powodować zmiany zawartości mikroskładników pokarmowych w roślinach, co może mieć znaczenie w żywieniu zwierząt. Na podstawie przeprowadzonych badań wykazano brak zmian w zawartości miedzi oraz wzrost zawartości cynku i manganu w tkankach roślin doświadczalnych pod wpływem zastosowanych dodatków siarki. O ile zawartości cynku nigdy nie przekraczały norm dla pasz, to zawartości manganu były w niektórych przypadkach nadmierne z punktu widzenia żywienia zwierząt. Należy jednak podkreślić, że już wyjściowa zawartość Mn w roślinach była zbyt wysoka, a dodatki siarki wpływały na jej dalsze podwyższenie.

EN

Mixed phosphate rock-S fertilizers were used in pot cultures of oat, lupin, maize, mustard and rye to study the distribution of Cu, Mn and Zn between plant tissue and soil. Two-year expts. did not show any increase in Cu content in the plant tissue while an increase in Zn and Mn contents were obsd. The Mn content in the plants was even much higher than the allowable in animal feed (1000 mg/kg).

7

Zwiększenie efektywności surowców fosforytowych poprzez dodatek siarki. Cz. 2, Wpływ nawozów fosforytowo-siarkowych na środowisko

Stanisławska-Glubiak E., Korzeniowska J., Hoffmann J., Kantek K.

Przemysł Chemiczny

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2012

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T. 91, nr 5

1000-1005

PL

W rolniczych doświadczeniach wegetacyjnych badano wpływ nawożenia mieszankami fosforytowo-siarkowymi (FS), sporządzonymi na bazie mielonego fosforytu z dodatkiem siarki, na zmiany odczynu gleby i zawartości w niej przyswajalnej dla roślin formy fosforu oraz przemieszczania się jonów fosforanowych i siarczanowych do wód. Mieszanki FS nie powodowały zmniejszenia wartości pH gleby, wzbogacając glebę w przyswajalny fosfor w drugim roku od ich zastosowania. Jednocześnie nie stanowiły zagrożenia dla środowiska glebowego i wodnego pod warunkiem, że stosunek fosforytu do siarki (F:S) nie był niższy niż 10:1.

EN

Fine and coarse phosphate rocks were compounded with elementary S and used as fertilizer in pot cultures of test plant to study the migration of P and S to soil and soil filtrates. The addn. of S did not result in any solubilization of phosphates. No risk to soil and aquatic environment was obsd. when the phosphate-S ratio was not lower than 10:1.

8

Ocena postępu reakcji rozkładu fosforytu kwasem siarkowym prowadzonej w warunkach metody PAPR

Skut J., Hoffmann J., Hoffmann K.

Przemysł Chemiczny

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2011

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T. 90, nr 5

1024-1028

9

Mechanochemiczna aktywizacja rudy fosforanowej w obecności zeolitu

Kic B., Grzmil B.

Przemysł Chemiczny

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2010

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T. 89, nr 4

414-418

10

Manufacturing NPK Fertilizers by modified wasteless Odda process

Folek S., Kopytowski J., Tomanek G., Walawska B.

Polish Journal of Chemical Technology

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2001

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Vol. 3, nr 4

3-5

EN

A novel approach to make granulated mineral fertilizers of the NPK type, which depends on a modification of the known Odda process is presented. In the method proposed, phosphate rock is digested with nitric(V) acid, part of the calcium ion is removed and next, potassium sulfate(VI) and phosphate rock are added to the reaction system to neutralize the resulting mixture of phosphoric(V) acid and the unreacted nitric acid. Investigations into the developing of the method were carried out within the Research Project No. 3 TO9 B 082 14, being supported financially by the Polish Committee of Scientific Research.