Particle Size Distribution Of Products Research Articles

An expeditious method for determining particle size distribution by near infrared spectroscopy: Comparison of PLS2 and ANN models

The particle size distribution of a solid product can be crucial parameter considering its application to different kinds of processes. The influence of particle size on near infrared (NIR) spectra has been used to develop effective alternative methods to traditional ones in order to determine this parameter. In this work, we used the chemometrical techniques partial least squares 2 (PLS2) and artificial neural networks (ANNs) to simultaneously predict several variables to the rapid construction of particle size distribution curves. The PLS2 algorithm relies on linear relations between variables, while the ANN technique can model non-linear systems. Samples were passed through sieves of different sieve opening in order to separate several size fractions that were used to construct two types of particle size distribution curves. The samples were recorded by NIR and their spectra were used with PLS2 and ANN to develop two calibration models for each. The correlation coefficients and relative standard errors of prediction (RSEP) have been used to assess the goodness of fit and accuracy of the results. The four calibration models studied provided statistically identical results based on RSEP values. Therefore, the combined use of NIR spectroscopy and PLS2 or ANN calibration models allows determining the particle size distributions accurately. The results obtained by ANN or PLS2 are statistically similar.

Block-based approach to modelling of granulated fertilizers' quality

Fertilizer manufacturing is a customer-driven industry, where the quality of a product is a key factor in order to survive the competition. However, measuring the most important feature with granulated fertilizers, flowability, is tedious, time-consuming and thus expensive. Flowability can be defined through testing the flow rate with, e.g., seed drill. Besides the chemical composition, flowability can be considered as one of the most important characteristics. There are numerous factors affecting the flowability of a granulated fertilizer, several of them related to the particle size distribution. Particle size distribution of the granulated product has to be within the customer specification, but is also a highly significant factor to the quality, especially in the presence of moisture. This can affect numerous phenomena, inter alia, agglomeration and aggregation of granules and Ostwald ripening, where the smallest crystals dissolve while the large ones grow. Chemical composition affects the crystallization process and is significant for particle shape and various physical properties. Sometimes, as in this case, the variables form a natural division into blocks. It may be of interest to observe the different effect of the blocks on the modelling task. The present approach is based on priority PLS and multi-block PLS. The data is measured from the final product and is divided into blocks between physical properties, such as granule hardness and roundness, chemical composition and particle size distribution. The goals are to find a reliable model for flowability using this data and to find the most important variables and to identify the effect of blocks to the quality.

粉砕方式を変えた転動ミル粉砕によるＳｒフェライト微粒子の生成

The processes for obtaining fine Sr-ferrite particles have direct efects upon the crystallite size and distribution of sintered Sr-ferrite specimens. The influence of grinding conditions on the production of fine Sr-ferrite particles during ball mill grinding was investigated. The grinding experiments were carried out under dry and wet conditions, and dry condition with methanol as a grinding aid. Particle size distributions of the ground products were measured by the microscopic method, and could be expressed accurately as described by a modified Gaudin-Schuhmann equation. The fine grindability of Sr-ferrite particles was evaluated by the median particle size in undersize distribution, and the ratio of 10% and 90% cumulative weight passing sizes that showed the broadness of the size distribution. Sr-ferrite particles with a median particle size of 0.8-1.0μm were produced. The broadness of the size distribution increased with decreasing median particle size of the ground products. The broadness of the size distribution by wet grinding and dry grinding with a grinding aid was lowered using larger grinding media.

Supercritical antisolvent micronization of minocycline hydrochloride

Micronization of minocycline hydrochloride dissolved in ethanol and with supercritical carbon dioxide as antisolvent was successfully performed using a supercritical antisolvent (SAS) apparatus. Amorphous particles of minocycline ranging from 0.1 to 1 μm (depending on the operating conditions) were obtained. The mean particle size and the particle size distribution were determined by dynamic light scattering. Images were obtained by Scanning Electron Microscopy (SEM) to confirm the morphology and the size of the powders before and after the material is processed. The quality of the micronized minocycline was analyzed by HPLC and was compared with that obtained before micronization. Experiments were carried out in order to study the effects of the pressure (75–130 bar), temperature (35–50 °C) and concentration of the liquid solution (1–20 mg mL −1) on the mean particle size and particle size distribution of the final product obtained. The effect of the antisolvent flow/liquid solution flow (AS/L) ratio was also analyzed. Experiments were performed with (AS/L) ratios equal to 5, 15 and 50 on a mass basis. The experimental results clearly indicate that SAS micronization of minocycline hydrochloride with ethanol as solvent and SC-CO 2 as antisolvent, above approximately 80 bar (the only region where it occurs), takes place in a homogeneous supercritical phase formed in the precipitator and particle formation results from gas-phase nucleation. This conclusion is consistent with results mentioned in the literature for similar systems.

Experimental identification of entropy model of comminution process

The entropy model based on population balance enables theoretical prediction of particle size distribution of comminution product. Selection and breakage functions occur in this model. The form of the selection function was determined experimentally. Informational entropy was used for the breakage function determination. Parameters of both functions can be estimated from experiments. The parameter identification of the entropy model was carried out on the basis of research on limestone comminution. Grinding tests were carried out in a laboratory fluidised bed jet mill. The results of the experimental identification confirm the accuracy of the entropy model.

Ultra-fine grinding of inorganic powders by stirred ball mill: Effect of process parameters on the particle size distribution of ground products and grinding energy efficiency

A series of wet grinding experiments have been carried out using a stirred ball mill to systematically investigate the effect of processing conditions on the final particle size distribution and grinding kinetics. A sub-micron particle size down to 350 nm was achieved, while the grinding energy efficiency or enhanced grinding rate was shown to be improved with the addition of grinding aids and with the use of smaller grinding media. A simple exponential relation was then proposed to quantitatively describe the observed grinding behavior by introducing the production rate constant,K. It is suggested that by usingK as a guideline, ways of improving the grinding energy efficiency can be established, e.g. use of smaller grinding media, choosing larger particle size class materials, etc.

Kinetics of magnesium hydroxide precipitation from sea bittern

Magnesium hydroxide is a valuable chemical produced almost in pure form from seawater and its bitterns through precipitation process. Product size distribution of magnesium hydroxide affects the ease of downstream processes of filtration and drying. Therefore, gaining insight into kinetic information in order to improve the size distribution of product particles is essential. In this work, a mechanistic model has been developed for precipitation of magnesium hydroxide from sea bittern. The parameters of model equations based on the population balance concept have been determined using the experimental data of precipitation from a pure synthetic solution containing 3% Mg 2+ and a sea bittern from salt production unit of a local petrochemical complex. The model suggests a higher nucleation rate coefficient and a lower growth rate coefficient for precipitation from the sea bittern compared to that from pure synthetic solution. The nucleation increase and growth decrease which were attributed to the effects of impurities in the bittern, would decrease the settling velocity of the product particles and therefore make the filtration process in industrial use more difficult. However, a larger coefficient of agglomeration rate was predicted by the model for precipitation from the bittern favor to product settling.

Particle size distributions a new approach

The consideration that the mass discontinuities of brittle materials statistically present fractal behavior makes available a new approach to the elucidation of crushing and grinding process. Through crushing and grinding experiments of characteristics brittle materials, the breakage distribution function (particle size distribution of products of a single breakage event) is defined as the sum of two distinct distribution (fragments and dust). The breakage distribution function follows a geometric dimensional scale and is depending on two new statistical characteristics constants of the material. Entering the number of breakage events, as the independent variable of the aforementioned function, a theoretical model of grinding process is formulated. The application of the theoretical model in any given size reduction process allows the definition of the process breakage probability distributions function and thus the theoretical model can be transformed to an actual simulation model of the process. The reliability of the new approach in describing the evolution of particle size distribution during the crushing or grinding was evaluated by its application in characteristics experimental and industrial installations.

Particle Size Coarsening Induced by Valve Silicone in a Metered Dose Inhaler

ABSTRACTThe objective of this study was to evaluate the effect of valve silicone on the delivered particle size distribution of a suspension metered dose inhaler (MDI). Valves were manufactured with distinct levels of silicone, which could be differentiated with Fourier transform infrared spectroscopy (FT-IR). The amount of silicone in the valve was proportional to the amount of silicone that entered the formulation and the subsequent decrease in fine particle fraction (FPF) of the active pharmaceutical ingredient (API) measured by Andersen cascade impaction. The effect of silicone content was not linear as even small amounts of silicone made a significant contribution to particle size coarsening. This coarsening was also a function of storage time and temperature. Accelerated stability conditions greatly increased coarsening kinetics as 1 month at 40°C and 75% RH induced significantly more coarsening than 12 months at room temperature. Field emission scanning electron micrograph images suggest that the primary mechanism of particle size change may be aggregation as particle clusters were seen. This study indicates that silicone can be a critical process parameter for particle size distribution of a suspension MDI product. Thus, the amount of silicone in the valves needs to be minimized and controlled.

Mass transfer and radical flux effects in dispersed‐phase polymerization of isooctyl acrylate

AbstractThe kinetics of dispersed phase polymerization of a highly water‐insoluble monomer (isooctyl acrylate) were explored in emulsion, miniemulsion, and microsuspension polymerization. The effects of monomer water solubility and choice of initiator (oil‐ vs. water‐soluble) strongly impact the final product (particle size and molecular weight distribution). For emulsion polymerization, as the surfactant concentration was increased, there was a transition from homogenous to micellar nucleation near the CMC, then a drop in nucleation rate at high surfactant concentration due to insufficient radical flux to support more nucleation. For miniemulsion polymerization, a slow rate of growth of (droplet) nucleation with surfactant concentration was found, followed (at the CMC) by an increase in the rate of nucleation with added surfactant as the mode of nucleation switched to micellar. The conversion‐time kinetics of microsuspensions could be modeled with a bulk polymerization model. IOA is sufficiently insoluble in the aqueous phase that emulsion polymerization may or may not be reaction limited. The presence of a stabilizer such a PAA, the use of an oil‐soluble initiator such as BPO, and the insolubility of IOA in the aqueous phase all push the polymerization locus toward droplet (microsuspension) nucleation and bulk kinetics.© 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5649–5666, 2006

The shape of product size distributions in stirred mills

This paper presents the results of an extensive laboratory and pilot stirred milling testwork program conducted using different types of mills, fed with different types of materials and operated at different conditions. The results indicate that the slope of the product size distribution (PSD) curve remains relatively unchanged in the coarse product size range but decreases in the fine product range (less than about 20 μm size), regardless of the type of stirred milling technology used for grinding. This work therefore confirms that a narrower product particle size distribution than the feed size can be achieved independent of the type of stirred milling technology used for fine grinding below 20 μm. The change in the PSD width in fine grinding is due to the change in the material breakage properties and a change in the mill operating conditions which affect the breakage process. In the normal operating range of grinding media size, the effect on the PSD shape is not significant.

Analysis of Industrial Grinding Circuits Using PCA, PLS and Neural Networks

The use of variable rotation speed control in mineral grinding circuits is continuously increasing. High precision on-line particle size distribution measurement of the grinding product has also recently become available. These tools have increased the potential for the development of monitoring and optimization methods for grinding circuits. This paper presents some experiments to evaluate the effect of mill operating variables on the particle size distribution of the circuit product. In the evaluation the PCA, PLS and neural networks methods were used for analyzing industrial experiment data. The experiments have been carried out at the Kemi chromite concentrator plant of Outokumpu Chrome in northern Finland.

Examination of the Polymorphs and Particle Size of Calcium Carbonate Precipitated Using Still Effluent (i.e., CaCl2 + NaCl Solution) of Soda Ash Manufacturing Process

The precipitation of calcium carbonate was studied by adding the sodium carbonate solution to a mixed system such as Still effluent (i.e., CaCl2 + NaCl solution) of the soda ash manufacturing (Solvay) process, and the effects of controlling factors on calcium carbonate polymorphs were investigated. The products were characterized with scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and powder X-ray diffraction analysis. The particle size distribution of products was determined as dry powder using laser diffraction technique. It was found that the dilute solutions of the reactants favor the aragonite formation without affecting much the particle size. The formation of calcite is favored with the increase in sodium carbonate concentration. The reaction temperature has no significant effect on polymorphism as well as particle size of calcium carbonate precipitated from solutions having concentration 1.25 M Ca2+ and 1.25 M CO32- and reaction time of 30 min. However, the mod...

Energy and population balances in comminution process modelling based on the informational entropy

The results of theoretical and experimental studies of a comminution process are presented. There are two random functions: the selection function and the breakage function in the stochastic model based on a population balance. This model enables prediction of particle size distributions of comminution products after determination of both random functions. Maximum entropy method is used in the entropy model for determining the breakage function. Two cases are analysed, based on continuous and discrete particle size distribution functions of the fed material. Apart from mass balance, the energy balance of comminution process is also used. Searched form of breakage function is determined with the application of methodology of calculus of variations. The results of experimental identification of both models are presented. The parameters that occur in the discrete form of the selection and breakage functions were the identification objects. The results of experimental investigations of quartz sand single comminution in a laboratory jet mill provided an identification base. The experimentally identified results of the entropy model confirmed the adequacy of the theoretical analysis and demonstrated the possibility of adequate prediction of particle size distributions resulting from single comminution.

Seeding and Constant-Supersaturation Control by ATR-FTIR in Anti-Solvent Crystallization

The strategy for seeding and supersaturation control can play a critical role in defining the purity and particle size distribution of crystal products. Previous research has demonstrated that operation of crystallizers at constant supersaturation by feedback control is attractive due to its simplicity and resistance to operating disturbances. In this study, the effects of seed loading and seed size distribution were investigated for anti-solvent crystallization of paracetamol from a water−acetone mixture operated at constant supersaturation. A seeding strategy based on a simple mass balance equation provided a good starting point for the refinement of particle size distribution and adjustment of batch time in different circumstances to obtain a target average crystal size with narrow size distribution.

Maximum Entropy Method in Comminution Modelling

This paper analyses the comminution process. There are two random functions: the selection function and the breakage function in the stochastic model based on population balance. Introducing the energy balance, applying the maximum informational entropy method and taking into consideration the normalized condition, enables us to formulate and solve the variational problem and determine the breakage function by Lagrange’s multipliers method. The above determination of the breakage function is an original new method. The sought form of the breakage function is an argument of the constrained extremum of an integral functional with two indirect conditions. The obtained form of the breakage function was applied to the equation of the population balance. This leads to the prediction of the particle size distribution of the single comminution product with an additional assumption concerning the form of the selection function.

Characteristics of Particle Size Distribution of Deoxidation Products with Mg, Zr, Al, Ca, Si/Mn and Mg/Al in Fe-10mass%Ni Alloy

In the experiments of an Fe–10mass%Ni alloy deoxidized with Mg, Zr, Al, Ca, Mn/Si and Al/Mg at 1873 K, the characteristics of particle size distributions have been studied as a function of holding time, amount of deoxidant and order of deoxidant addition. The peak height in particle size distribution decreases and the modal value increases with increasing holding time. The width of the distribution curve is larger for Al2O3 particles and smaller for liquid CaO–Al2O3 and MnO–SiO2 particles. The number of particles increases with an increase of deoxidant for a given initial oxygen content and holding time. In the case of Al followed by Mg deoxidation, the particle size distribution is almost the same as that obtained by only Al. The size distribution in case of Mg followed by Al deoxidation is almost the same as that by only Mg.

Effect of Inherent Variability of Inhalation Products on Impactor Mass Balance Limits

When measuring the aerodynamic particle size distribution of pulmonary drug products, the commonly used instrument is a cascade impactor. For this type of analysis, a mass balance (MB) criterion, 85-115% of label claim, has been recommended by the U.S. Food and Drug Administration (FDA) to be included in the drug product specification. Using statistical model simulations, the effect of inherent product variability on the risk to fail the proposed criteria has been assessed and compared to the corresponding risk to fail the delivered dose uniformity (DDU) test. The results clearly show that the MB criterion is at odds with typical variability of orally inhaled products and seriously contributes to the risk that a typical batch would be rejected due to natural variability of the delivered dose of the product. The MB criterion is generally more difficult to comply with compared to the corresponding delivered dose uniformity (DDU) test, indicating that the proposed FDA MB specification overrules the DDU criteria as being that controlling the DDU.

Alternative Filter Media for Phosphorous Removal in a Horizontal Subsurface Flow Constructed Wetland

During the study period from 1997 to 2002 the purification efficiency of phosphorus in the horizontal subsurface flow (HSSF) constructed wetland (CW) in Kodijärve, has been quite high (63–95%). However, slowly increasing trend in outlet P concentrations and decreasing annual P removal rate are obviously the indicators that show possible saturation processes in filter media. To search for potential filter media with high phosphorus sorption capacity, sorption characteristics and particle size distribution of several local sands, gravels, glauconite-sandstone, LWA, and calcareous waste products from oil-shale industry were investigated. The average P sorption capacity for best materials (crashed ash block, oil, shale fly ash and the sediment from oil shale ash plateau) was higher than 96% and estimated design capacity was around 4–5 g P kg−1. According to results, sediment from oil shale ash plateau was considered as perspective filter media for P retention. In Summer 2002 experimental sedimentation filter, filled with the sediment from oil shale ash plateau, was installed in the outlet from the Kodijärve HSSF CW. According to preliminary results the average P removal in the sedimentation filter was 52%.

Droplet and Particle Dynamics during Flame Spray Synthesis of Nanoparticles

Particle formation by flame spray pyrolysis is investigated theoretically and compared with particle size distribution data of ZrO2 production at 100−300 g/h. Spray droplet size distributions as well as droplet and gas velocities are measured by phase Doppler anemometry along the axis and radius of the solid-cone-type spray. Multicomponent droplet combustion is simulated, accounting for droplet polydispersity, transport, and evaporation. The dynamics of the product particle size distributions are investigated, accounting for coagulation and sintering by population balance equations. The effect of the initial droplet size and liquid feed rate on the evolution of the product particle size and polydispersity is analyzed.