Solubility and agronomic effectiveness of partially acidulated phosphate rocks as influenced by their iron and aluminium oxide content

1989 ◽  
Vol 19 (2) ◽  
pp. 93-98 ◽  
Author(s):  
L. L. Hammond ◽  
S. H. Chien ◽  
A. H. Roy ◽  
A. U. Mokwunye
Keyword(s):  
Aluminium Oxide ◽  
Oxide Content ◽  
Phosphate Rocks ◽  
Agronomic Effectiveness ◽  
Partially Acidulated Phosphate Rocks

Partially acidulated phosphate rocks: Phosphorus release characteristics

1990 ◽  
Vol 22 (2) ◽  
pp. 109-117 ◽  
Author(s):  
J. Hagin ◽  
S. S. S. Rajan ◽  
M. K. Boyes ◽  
M. Upsdell
Keyword(s):  
Phosphorus Release ◽  
Phosphate Rocks ◽  
Partially Acidulated Phosphate Rocks

scholarly journals Obtaining the partially acidulated phosphate rocks by means of intermediate-grade phosphate and diluted phosphoric acid: Influence of some parameters

2016 ◽  
Vol 18 (3) ◽  
pp. 39-43
Author(s):  
Abbes Mizane ◽  
Ahmed Boumerah ◽  
Noureddine Dadda ◽  
Rabah Rehamnia ◽  
Salah Belhait
Keyword(s):  
Phosphoric Acid ◽  
Reaction Times ◽  
Water Soluble ◽  
Particle Sizes ◽  
Phosphate Rocks ◽  
Partially Acidulated Phosphate Rocks ◽  
Water Soluble P ◽  
Conversion Rates ◽  
Soluble P ◽  
Phosphoric Acid Concentration

Abstract In this work, some parameters during the partial acidulation by phosphoric acid of phosphate 53.75% BPL (bone phosphate of lime) having different particle sizes are determined. P2O5 recovery is obtained by performing a series of reactions using phosphoric acid diluted from 10 to 40 wt.% and with reaction times ranging from 10 to 50 minutes. The best conversion rates are obtained with the following reaction parameters: phosphates size: 88-177 μm, reaction time: 50 minutes and phosphoric acid concentration: 40 wt.%. In the second part, the water-soluble P2O5 of PAPRs (Partially Acidulated Phosphate Rocks) obtained with phosphoric acid 30% and 40 wt.% is measured. The results of experiments showed that the water-soluble P2O5 has reached 15.2% for PAPRs obtained by reacting phosphate 88 μm with phosphoric acid 40 wt%.

scholarly journals Ferroelectric Aspect and Phase Transitions of Solid Solution of Cadmium Acetate with Aluminium (III) Oxide

2021 ◽  
Vol 04 (08) ◽  
Author(s):  
Shri Prakash Dubey ◽  
Keyword(s):  
Solid Solution ◽  
Dielectric Constant ◽  
Resonant Frequency ◽  
Quality Factor ◽  
Aluminium Oxide ◽  
Cadmium Acetate ◽  
Effect Of Temperature ◽  
Oxide Content ◽  
Cooling Cycle ◽  
Bridge Model

The behavior of variation of dielectric constant with temperature of solid solution of Cadmium Acetate Cd(C2H3O2)2 with Aluminium (III) Oxide Al2O3 and other dielectric parameters have been measured between the temperatures 35°C to 100°C using the capacitance bridge model ZENITH-FM89A and Q meter at the frequency of 2000 Hz. In the measurement, it have been observed that the compound has lower value of dielectric constant (ε = 1580) below 36ºC, which rises upto a value of 5600 at the moderate temperature of 45ºC. After this temperature, the dielectric constant of compound decreases upto the value of nearly 3521 at the temperature of 75ºC and a high peak at the temperature of 76°C (ε = 7000) in the heating cycle curve with some fluctuations.. When the variation of dielectric constant was studied in cooling cycle the peak was observed at 62ºC(ε = 6500), above and below this temperature dielectric constant decreases with some intermediate fluctuations and by increasing aluminium oxide content in the mother compound, its quality factor also increases with a little effect on dielectric constant. The cooling cycle curve does not follow heating curve because of the relaxor behaviour of the compound. The results have been explained on the basis of crystal structure changes and the possibility of free internal rotation of acetate groups within the crystal lattice at elevated temperature. One of the advantages of Cd(C2H3O2)2 with Al2O3 is that by varying the Aluminium Oxide content, one can control temperature coefficient of resonant frequency τf without affecting the other properties. This is important for many ferroelectric applications because τf of near about low value is not always required. A non-zero τf is often preferable to compensate for frequency variation due to the effect of temperature change on the resonator housing and dielectric support structure. Solid solution of Cadmium Acetate with Aluminium Oxide suggests for its valuable applications as dielectric material with excellent properties useful in ceramics engineering and communication system. KEY WORDS: Polarization, Quality Factor, Dielectric Constant, Phase Transition, Curie temperature, Resonant Frequency and Ceramics Engineering.

Developments in some aspects of reactive phosphate rock research and use in New Zealand

1997 ◽  
Vol 37 (8) ◽  
pp. 861 ◽  
Author(s):  
N. S. Bolan ◽  
M. J. Hedley
Keyword(s):  
New Zealand ◽  
Phosphate Rock ◽  
Direct Application ◽  
Soil Test ◽  
Phosphate Rocks ◽  
Agronomic Effectiveness ◽  
Olsen P ◽  
The North ◽  
Soluble P ◽  
P Sources

Summary. There has been over 50 years of use and research into the agronomic effectiveness of reactive phosphate rocks (RPR) directly applied to New Zealand pastures. In recent years RPR-carrying fertilisers made up about 16% of phosphatic fertiliser sales in the North Island of New Zealand. Most is applied, as maintenance fertiliser, to hill country sheep and beef farms. Use has been recommended on soils with pH <6 and in annual rainfall regimes >800 mm. This is based on the poor performance of Sechura phosphate rock in summer dry areas receiving <750 mm of rainfall annually. Phosphate rocks that have more than 30% of their total phosphate soluble in 2% citric acid have been classed as ‘reactive’ and suitable for direct application. More recent research indicates that extraction with 2% formic acid, or a dissolution test performed in a simulated soil solution at a fixed pH, will provide improved measures of RPR quality. Field trials, undertaken by the New Zealand Ministry of Agriculture and Fisheries [MAF; now AgResearch Crown Research Institute (CRI)] and others, to evaluate the relative agronomic effectiveness of RPR versus soluble P fertilisers in adequate to marginally P-deficient soils have proven to be a painstaking task. Long periods (3–6 years) of fertiliser withdrawal were required for pasture growth on some soils to become significantly responsive to applied P. Only then did differences between P sources become significant. This problem has encouraged efforts to relate measurements of the extent of RPR dissolution in soils to their agronomic effectiveness. Three main modelling approaches have been used to achieve this objective: Kirk and Nye (1986a, 1986b, 1986c); Sinclair et al. (1993a); and Watkinson (1994b). These models are reviewed and their explanation of RPR dissolution in mowing trials tested. Components of each model have then been combined to produce models to predict the agronomic effectiveness of RPR. The development of P tests for soils receiving RPR-containing fertilisers is reviewed. Separate Olsen P test–yield response calibration curves are required for soils fertilised with soluble P fertilisers and soils fertilised with sparingly soluble P sources or soluble P in the presence of heavy lime applications. Whereas alkaline P tests such as Olsen or Colwell underestimate the amount of plant-available P in these soils, acid P tests such as Bray 1 are likely to overestimate the available P. Tests involving cation and anion exchange resin membranes appear to be more appropriate for soils with unknown histories of soluble P and RPR use and may permit the use of single calibration curves. Trends observed in Olsen P soil test values, from farms on the North Island of New Zealand that have a history (3–15 years) of RPR use are presented. A predictive dissolution model is used to explain these trends but it is evident that spatial and temporal variation in soil test results on farmers’ paddocks will be a major constraint to the precision to which this or similar models may be used. The model, however, may provide the basis for sound advice on the strategic use of RPR for direct application to New Zealand pasture soils. It may prove useful in explaining the variation in RPR effectiveness in a wider range of climates and soils.

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