Impurities In Phosphoric Acid Research Articles

Statistical Study and Modeling of the Effect of Phosphoric Acid Impurities on the Physical Quality of Ammonium Phosphate Determined from the Production Data Using Artificial Neural Network

The monitoring of the physical properties of fertilizers presents a lot of interest at different levels. All the problems related to the behavior of the granules (segregation, spreading, granulation, hardness…) need a better characterization of the fertilizers in order to understand and/or predict them. The scientific community is led to develop a variety of modeling approaches for, on the one hand, the understanding of the dynamics of impurities originating from phosphoric acid during the manufacture of fertilizers, and on the other hand, the evaluation of the effectiveness of measurements and data monitoring from production and the fluctuations in the physical quality of the fertilizers that follow. In this investigation of the influence of elements such as Fe, Al, Mg, F-, Si, Na, K and Cl on fertilizer quality, we gathered and followed-up data from production lines of Ammonium phosphate fertilizers for several months. The aim of the current work is the statistical study and modeling of the phosphoric acid impurities effect on the physical quality of fertilizers such as granulation yield, grain size, and the average diameter of granules D50, based on the analysis of data from different production lines by applying the Artificial Neural Network (ANN) approach. In addition models, were constructed using Multiple Linear Regression (MLR) and Principal Components Analysis (PCA).

Determination of elemental impurities in phosphoric acid by INAA employing a novel method of phosphate precipitation

Banned irradiation of liquid acids in many nuclear reactors requires a transformation of these compounds into a solid substance to be able to perform the determination of impurities using instrumental neutron activation analysis. For this purpose, a novel, simple, and contamination-free procedure for the transformation of phosphoric acid into ammonium phosphate has been developed, which is based on isothermal distillation of ammonia vapours. Favourably low detection limits for more than 35 elements have been achieved and the accuracy of the results has been established by analysis of NIST SRM 1515 Apple Leaves.

Corrosion of graphite in industrial phosphoric acid

The electrochemical corrosion of graphite in industrial phosphoric acid solutions was studied using polarisation curves analysis, cyclic voltammetry, MEB–EDS and secondary ions mass spectroscopy (SIMS). The polarisation curves indicated that graphite has a passive behaviour and the increase of temperature induces an increase of the corrosion rate and the passive current density. The cyclic voltammetry analysis was performed to verify the surface phenomenon of graphite surface and confirmed the role of adsorption oxygen in material corrosion. Spectroscopic analysis (EDS and SIMS) showed that the majority of industrial phosphoric acid impurities were present in the graphite composition indicating that metallic oxides are not the only components of this layer. The presence of these impurities on the graphite induces an increase of corrosion by swelling, exfoliation and cracking.

Sulphide Precipitation of Iron and its Effect on the Extraction of Uranium from Phosphoric Acid Medium

The pres-ence of such impurities in phosphoric acid adversely affectsthe process performance as well as the quality of producedacid. Further, the dissolved iron has a strong effect onincreasing the acid viscosity and consequently decreasing thefiltration rate. Iron also forms precipitates during concentra-tion, clarification, and storage causing sludge problems accom-panied by P

Effect of impurities in phosphoric acid on the granulometery of the produced DAP(Di-ammonium PHOSPHATE) in petrochemical plants

The influence of impurities in phosphoric acid on the granulometery of the produced DAP was experimentally investigated in a petrochemical plant. It was found that DAP granulometery can be substantially improved as the total concentration of aluminum and iron oxides in the phosphoric acid is increased up to 2.2±0.1 wt%. A correlation was proposed for predicting the DAP granulometery in terms of total concentrations percent of (Al2O3+Fe2O3) in the phosphoric acid.

STEADY STATE SIMULATION OF PHOSPHORIC ACID CONCENTRATION PROCESS

Steady-state simulation of wet phosphoric acid concentration process was carried out using process engineering simulator SCAPE (Software for Computer Aided Process Engineering), with the aim to study process performances. Industrial phosphoric acid was characterized by a mixture of phosphoric acid, water, and impurities in aqueous solution. The major phosphoric acid impurities were represented by a pseudocomponent. The Peng–Robinson equation of state was adapted to calculate phase equilibrium for industrial phosphoric acid using the pseudocomponent approach. The simulation of many points of cycle of phosphoric acid concentration process was carried out. The results obtained were compared to process data. The mean absolute relative error was within 0.4% for boiler temperature, 0.9% for heat exchanger outlet temperature, 0.3% for P2O5 mass content of concentrated phosphoric acid, and 0.4% for concentrated phosphoric acid mass flow rate. The sensitivity of P2O5 mass concentration of concentrated phosphoric acid vs. the main process parameters such as steam and weak phosphoric acid feeds, boiler pressure, and impurities mass content of weak phosphoric acid was studied.

Effect of aluminum, iron, and magnesium upon the solubility of .alpha.-calcium sulfate hemihydrate in 40%, 45%, 50%, and 55% P2O5 phosphoric acid solutions at 80, 90, 100, and 110.degree.C: correlations with water concentration

The influence of the common wet-process phosphoric acid impurities [Al 2 O 3 (1.50%), Fe 2 O 3 (2.15%), and MgO (0.50%)] upon the solubility of α-calcium sulfate hemihydrate in 40%, 45%, 50%, and 55% P 2 O 5 phosphoric acid solutions at 80, 90, 100, and 110°C, respectively, were measured

Influence of impurities in phosphoric acid on the corrosion resistance of some commercially produced alloys

The influence of Cl −, F −, S 2−, SO 2− 4, SiO 2− 3, Fe 3+, Al 3+, Ca 2+ and Mg 2+ ions, in phosphoric acid, on the corrosion behaviour of stainless steels 304 and 316, alloys 825, 625, 230 and Hastelloys C and G was investigated. The alloys were tested in 75% H 3PO 4 in the absence and presence of various concentrations of each of the impurities at 85 °C under reflux and stirring conditions. Chloride ion was the most aggressive of the impurities because of its physicochemical properties. The best corrosion resistance in chloride contaminated H 3PO 4 was shown by the alloy containing the highest molybdenum and tungsten contents as an insoluble protective basic molybdenum and tungsten chloride film is formed. The presence of sulphide ion in H 3PO 4 considerably affected the corrosion rate as a result of the increased electrocatalytic activity of the passive film for oxygen reduction as a result of film contamination. Corrosion resistance was improved in such a sulphide environment by increasing the chromium content of the alloys.

Sintering and recrystallization of small metal particles. Loss of surface area by platinum-black fuel-cell electrocatalysts

Operation of high-surface-area platinum-black electrodes in hot concentrated phosphoric acid produces a loss of surface area with time, giving consequent loss of performance. The loss of surface area is the result of sintering produced by surface migration of platinum atoms on the individual crystallites to sites of lower surface energy. As the sintering process is a surface phenomenon, potential changes cause changes in the surface tensions of the metal crystallites giving rise to variations in sintering rate. The rate of sintering is greatest at low potentials and smallest at high. Carbon monoxide and phosphoric acid impurities adsorbed on the surfaces of the platinum crystallites retard the sintering at low potentials. Similar adsorption-induced changes in physical properties of materials (Rebinder effects) have been observed with ionic solids, but in only a few instances is this effect known to operate on metals. The presence of a strongly adsorbed molecule on the metal surface alters the inter-atomic bonding between the surface metal atoms and illustrates the dependence of the sintering mechanism on the mobility of the surface atoms. Changes in crystallite morphology accompany the sintering process and are considered to be the result of a surface rearrangement of ad-atoms or clumps with elimination of the [100] faces. The activation energy for the sintering process is 25 ± 2 kcal/mole at 0·5 V and is not significantly changed by adsorbed carbon monoxide on the platinum.

Phosphoric Acid Impurities, Precipitated Impurities in Wet-Process Phosphoric Acid

Phosphoric Acid Impurities, Precipitated Impurities in Wet-Process Phosphoric Acid