Solubility and application effects of African low-grade phosphate rock calcinated with potassium carbonate

Nakamura, Satoshi; Kanda, Takashi; Imai, Toshio; Sawadogo, Jacques; Nagumo, Fujio

doi:10.1080/00380768.2019.1598236

Cited by 12 publications

(17 citation statements)

References 19 publications

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“…Thus, phase modification of CaKPO 4 incorporated Na and has different reflexes (Fig. 3) as previous reported phase modification of CaKPO 4 [24,37].…”

Section: Phase Analysis In Laboratory-scale Calcination Experimentssupporting

confidence: 87%

“…The additional costs for the more expensive K additives might be compensated by the value of K in the fertilizer. Potassium hydroxide (KOH) [23] and potassium carbonate (K 2 CO 3 ) [24] were successfully tested to convert P compounds to highly plant available CaKPO 4 . Potassium sulfate (K 2 SO 4 ) could be also a suitable additive because it is a by-product of biofuel production [25] and can be available at a reasonable price.…”

Section: Introductionmentioning

confidence: 99%

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Crystalline phase analysis and phosphorus availability after thermochemical treatment of sewage sludge ash with sodium and potassium sulfates for fertilizer production

Herzel

Aydın

Adam

2021

J Mater Cycles Waste Manag

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Phosphorus rich sewage sludge ash is a promising source to produce phosphorus recycling fertilizer. However, the low plant availability of phosphorus in these ashes makes a treatment necessary. A thermochemical treatment (800–1000 °C) with alkali additives transforms poorly plant available phosphorus phases to highly plant available calcium alkali phosphates (Ca,Mg)(Na,K)PO4. In this study, we investigate the use of K2SO4 as additive to produce a phosphorus potassium fertilizer in laboratory-scale experiments (crucible). Pure K2SO4 is not suitable as high reaction temperatures are required due to the high melting point of K2SO4. To overcome this barrier, we carried out series of experiments with mixtures of K2SO4 and Na2SO4 resulting in a lower economically feasible reaction temperature (900–1000 °C). In this way, the produced phosphorus potassium fertilizers (8.4 wt.% K, 7.6 wt.% P) was highly plant available for phosphorus indicated by complete extractable phosphorus in neutral ammonium citrate solution. The added potassium is, in contrast to sodium, preferably incorporated into silicates instead of phosphorus phases. Thus, the highly extractable phase (Ca,Mg)(Na,K)PO4 in the thermochemical products contain less potassium than expected. This preferred incorporation is confirmed by a pilot-scale trial (rotary kiln) and thermodynamic calculation.

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“…Thus, phase modification of CaKPO 4 incorporated Na and has different reflexes (Fig. 3) as previous reported phase modification of CaKPO 4 [24,37].…”

Section: Phase Analysis In Laboratory-scale Calcination Experimentssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Crystalline phase analysis and phosphorus availability after thermochemical treatment of sewage sludge ash with sodium and potassium sulfates for fertilizer production

Herzel

Aydın

Adam

2021

J Mater Cycles Waste Manag

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“…Two types of calcined BPR (CB) were produced. Briefly, BPR was well mixed with potassium carbonate (K 2 CO 3 ) to produce CBk [26] and K 2 CO 3 + calcium carbonate (CaCO 3 ) to produce CBkca, and these were then calcined for 10 minutes at 900˚C for CBk and 1,000˚C for CBkca to increase the P solubility.…”

Section: Experimental Design and Field Proceduresmentioning

confidence: 99%

“…Calcined low-grade Christmas Island PR (Australia) showed a comparable effect to superphosphate (SSP) for radish yields on silt loam soils [25], while there was no significant effect on wheat production [19]. A modified calcination method for low-grade BPR was developed and achieved a high 2% citric acid solubility [26]. These calcined PRs were comparable with TSP at improving rice biomass production in pot experiments [26].…”

Section: Introductionmentioning

confidence: 99%

“…A modified calcination method for low-grade BPR was developed and achieved a high 2% citric acid solubility [26]. These calcined PRs were comparable with TSP at improving rice biomass production in pot experiments [26]. However, the effects of PAPR and calcined PR on rice cultivation in different soil conditions remain poorly understood, especially in West Africa.…”

Section: Introductionmentioning

confidence: 99%

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Site-specific responses of lowland rice to acidulated and calcined phosphate rock fertilizers in the Center-West region of Burkina Faso

et al. 2021

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Soil phosphorus (P) deficiency is a major constraint of crop production in Sub-Saharan Africa. In particular, in the Sudano-Sahelian zone of Burkina Faso, P is rarely replenished as fertilizer supplies are limited in rural areas and because of the socio-economic situation of farmers. There is however, an abundance of local phosphate rock resource in the country. The development of local inorganic P fertilizers to improve crop production and replace the nutrients removed after harvesting, as well as to promote to sustainable agriculture, is desired. This study evaluated the efficiency of low-grade Burkina Faso phosphate rock (BPR)-based P fertilizers, produced by acidulation and calcination-the major fertilizer processing methods, on lowland rice production and the soil factors influencing their effectiveness. The results showed that the acidulated P fertilizers were as effective as conventional commercial P fertilizers on various soil types, textures, and fertility. Calcined P fertilizers were consistently effective on fine-textured soils with high basic fertility. It was found that fine soil texture and basic fertility of the initial soils were important factors in agronomic efficiency of BPR-based fertilizers and the resilience of rice production to climatic variability. It is recommended that soil type, with respect to soil texture, soil properties, inherent fertility, and water availability, should be considered when using BPR-based fertilizers for rice cultivation.

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Thermodynamic properties of calcium alkali phosphates Ca(Na,K)PO4

et al. 2020

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Calcium alkali phosphates Ca(Na,K)PO 4 are main constituents of bioceramics and thermochemically produced phosphorus fertilizers because of their bioavailability. Sparse thermodynamic data are available for the endmembers CaNaPO 4 and CaKPO 4. In this work, the missing data were determined for the low-temperature phase modifications of the endmembers CaNaPO 4 and CaKPO 4 and three intermediate Ca(Na,K)PO 4 compositions. Standard enthalpy of formation ranges from-2018.3 ± 2.2 kJ mol-1 to-2030.5 ± 2.1 kJ mol-1 and standard entropy from 137.2 ± 1.0 J mol-1 K-1 to 148.6 ± 1.0 J mol-1 K-1 from sodium endmember b-CaNaPO 4 to potassium endmember b 0-CaKPO 4. Thermodynamic functions are calculated up to 1400 K for endmembers and the sodium-rich intermediate phase b-Ca(Na 0.93 K 0.07)PO 4. Functions above 640 K are extrapolated because of the phase transition from low-to high-temperature phase. Impurities in the synthesized intermediate phases c-Ca(Na 0.4 K 0.6)PO 4 and c-Ca(Na 0.35 K 0.65)PO 4 and one additional phase transition around 500 K impeded the determination of high-temperature thermodynamic functions. In general, data for phase transition temperatures agree with the previously reported phase diagrams.

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Solubility and application effects of African low-grade phosphate rock calcinated with potassium carbonate

Cited by 12 publications

References 19 publications

Crystalline phase analysis and phosphorus availability after thermochemical treatment of sewage sludge ash with sodium and potassium sulfates for fertilizer production

Crystalline phase analysis and phosphorus availability after thermochemical treatment of sewage sludge ash with sodium and potassium sulfates for fertilizer production

Site-specific responses of lowland rice to acidulated and calcined phosphate rock fertilizers in the Center-West region of Burkina Faso

Thermodynamic properties of calcium alkali phosphates Ca(Na,K)PO4

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