Calcium Carbonate Particle Size Research Articles

Effect of various factors on the particle size of calcium carbonate formed in a precipitation process

The effect of various factors on the particle size of precipitated calcium carbonate formed in a wet carbonation process has been investigated experimentally. The calcium carbonate particles were fabricated in a glass reactor by bubbling CO 2 through a calcium hydroxide solution of 2.5% by weight. The particle size distribution of the particles was determined using a laser technique. The operating factors investigated include the CO 2 bubble size (with frit pore size of 17–40 or 101–160 μm), the CO 2 gas flow rate (3.5 and 4 L/min), the CO 2 concentration (25 and 100%), the reaction temperature (25 and 80 °C) and the additives (terpineol 0.1 and 1 vol%, EDTA 0.25 and 1 wt%). It was found that the average particle size was between 1 and 3 μm. The particle size was reduced slightly with the decrease of the CO 2 bubble size, and decrease of the CO 2 concentration. The particle size distribution was affected significantly by the addition of terpineol and EDTA, but not necessarily reduced as reported previously.

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...

Effect of calcium carbonate particle size on PVC foam

AbstractCalcium carbonate is the predominant filler used in polyvinyl chloride compounding. Selection of fillers, as in the case with other compounding ingredients, involves consideration of available types and their effects on processing, product properties, and economics. In this article the effect of the particle size of CaCO3 on the properties of PVC foam is investigated. The study analyzes the correlation between fusion time, extrusion torque, and foam density as well as foam cell structure with the filler particle size. J. VINYL. ADDIT. TECHNOL. 12:55–57, 2006. © 2006 Society of Plastics Engineers.

Effect of solids formulation on the manufacture of high shear mixer agglomerates

Abstract The strength and morphology of granules generated by high shear agglomeration of powder with a highly viscous surfactant paste were investigated as a function of mixing time and powder particle size. The formulations featured a fine powder (zeolite or calcium carbonate) and linear alkylbenzene sulfonate (LAS) in a ratio of 1.7 : 1 by volume. During agglomeration, the solid material progressed through a number of consistency regimes up to the formation of a smooth dough. Differences in calcium carbonate (calcite) particle size had a significant effect on the agglomeration behavior, in that an increase in the mean diameter reduced the time required to form the dough state. Micrographic visualization, coupled with bulk density and Hausner ratio measurements, suggested that all the systems studied followed the same agglomeration mechanisms up to a certain point, albeit at different rates. The LAS-calcite mixtures appeared to be more compressible than zeolite mixes with similar particle size, although the overall trends in the compaction parameters were similar. None of the LAS-calcite mixtures attained an intermediate ‘crumble-agglomerate’ regime observed with the zeolite, which is attributed to the extensive hydrate-forming properties of the latter.

Precipitation of calcium carbonate in the presence of citrate and EDTA

The influence of process conditions such as feed rate, calcium/carbonate ratio, pH, complexing agents [ethylenediaminetetraacetic acid (EDTA), citrate (CIT)] and their concentration on the average particle size and shape of precipitated calcium carbonate was studied. The precipitation was performed in a semi-batch operated agitated vessel at constant pH by adding sodium hydrogen carbonate to a solution containing calcium chloride. In the absence of a complexing agent, agglomerates of needle-shaped crystals, probably aragonite, are obtained. Increasing feed time and the calcium/carbonate ratio increases the average particle size, whereas the opposite effect is observed for increasing pH. The observations can be related to the level of supersaturation. In the presence of complexing agents and at a concentration ratio of calcium vs. a complexing agent of 6, differently shaped and smaller particles were obtained. Furthermore, the effect of the other parameters on particle size becomes much weaker in the presence of complexing agents. In the presence of EDTA mostly spherical particles were obtained, and in the presence of citrate mainly rhombic particles corresponding to calcite were obtained. The effect on particle shape and size is attributed to interactions of the complexing agents with the faces of the crystalline calcium carbonate.

Reaction Crystallization of CaCO3 in a Gas-Liquid Multistage Column Crystallizer.

A multistage column crystallizer is a column crystallizer partitioned with perforated plates. From the viewpoint of economy, multistage column crystallizers have been developed to overcome the redundancy of equipment due to the duplication of mixers and other hardware in a cascade of mixed-suspension, mixed-product-removal crystallizers. The aims of this study are to clarify the characteristics of the multistage column crystallizers and to control the calcium carbonate particle size. The staging effects of the column crystallizer on the particle size were experimentally investigated by the gas-liquid reaction crystallization of calcium carbonate in the three-stage column crystallizer. The particle size of calcium carbonate obtained by the multistage column crystallizer becomes larger than that obtained by the standard column crystallizer. The dominant particle size increases with a decreasing opening ratio of the perforated plate, whereas it decreases with increasing CO2 content in the gas, because the particles produced re-dissolve by the dissolution of CO2.

加圧熱水中での古紙の糖化に及ぼす炭酸カルシウムの影響

The saccharification of waste paper such as old handbill using hot compressed water (HCW) was carried out in a batch reactor of 6ml inner-volume and a semicontinuous reactor of 28ml inner-volume. Hindrance effects of added amount and particle size of calcium carbonate and promotive effect of several additives on saccharification of waste paper were examined. It was demonstrated that the sodium pyrophosphate and aluminum phosphate have a remarkable promotive effect in saccharification of a model system, mixture of cellulose and calcium carbonate powder with a few decades microns. However, sodium pyrophosphate and aluminum phosphate were slightly effective for waste paper compared to the model system, because of highly reactive nanosized calcium carbonate contained in the waste paper.It was suggested that organic acids formed from cellulose at an initial stage of the saccharification reacted with nanosized calcium carbonate prior to hydrolysis of cellulose by HCW, and that as the result, pH of the reaction solution was raised up and thermal decomposition of saccharide was promoted.

Particle morphology of calcium carbonate precipitated by gas–liquid reaction in a Couette–Taylor reactor

The morphology and size of calcium carbonate particles produced by CO 2–Ca(OH) 2 reaction precipitation in a Couette–Taylor reactor were investigated experimentally. It was found that the change of particle morphology and size was caused dominantly by the excess species of reactants in the solution. As their measure, the relative enhancement factor Er involving the operation variables was introduced for the first time. The largest mean particle size and the most cube-like particle shape were observed at Er=1, implying the stoichiometric reaction condition. As the Er-value deviates from unity, particle morphology shifted to the spindle-like shape and mean particle size decreased with an increase in excess species concentration in the solution. The effect of excess species on particle size was predicted by the Bliznakov equation based on the monolayer adsorption. The correlation of particle size at various operating conditions represented the experimental data very well.

Control of calcium carbonate particle size and shape by precipitation from CTAB/alcohol/hexadecane mixtures

When used as a precipitation media, emulsified mixtures of cetyltrimethylarnrnonium bromide/n-butanol (E), hexadecane (O) and water (W), controls the size and shape of calcium carbonate particles. Monodisperse 2-micron spherical-calcite particles were obtained in a water-rich region of the mixture, while 2-micron rhombohedralcalcite particles with an aspect ratio near one were obtained in the middle region of the mixture. Replacing n-butanol with i-butanol led to consistent formation of monodisperse spherical particles, while using n-propanol in place of n-butanol limited the number of spherical particles produced in the water-rich region.

たばこ用巻紙の物性と紙層構造に及ぼす炭酸カルシウムの結晶形状および粒子径の影響

たばこ用巻紙の物性と紙層構造に及ぼす炭酸カルシウムの結晶形状および粒子径の影響

Effect of Concentration of Calcium Hydroxide Suspension on Particle Size of Basic Calcium Carbonate

Effect of Concentration of Calcium Hydroxide Suspension on Particle Size of Basic Calcium Carbonate

Calcium solubilization and retention in the gastrointestinal tract in chicks (Gallus domesticus) as a function of gastric acid secretion inhibition and of calcium carbonate particle size.

In chicks, immature pullets and laying hens, the inhibition of gastric acid secretion by omeprazole, an H+,K(+)-transporting ATPase (EC 3.6.1.36) inhibitor, greatly increased proventricular and gizzard pH values. Consequently, gizzard soluble Ca concentration deceased and the insoluble Ca fraction increased. Inhibition of acid secretion increased duodenal pH values in immature pullets and laying hens but not in chicks. Duodenal soluble and ionic Ca concentrations were lowered by gastric acid inhibition in chicks and to a larger extent in immature pullets and laying hens. The use of Ca of coarse particle size increased the gizzard insoluble Ca fraction in chicks and pullets. However, it did not influence its soluble Ca fraction in chicks but tended to reinforce the negative effect of omeprazole on soluble Ca in the gizzard and duodenum of chicks and laying hens. Coarse particles of Ca led to an increase in gizzard and duodenal soluble Ca at the end of eggshell calcification in laying hens. An enhancement in the level of Ca in the diet from 10 to 36 g/kg increased gizzard soluble Ca and duodenal soluble and ionic Ca concentrations in immature and adult hens. Intestinal Ca retention and bone mineralization was unaffected by gastric acid inhibition in chicks but were largely diminished by the use of coarse particles of Ca. Gastric acid inhibition was associated in laying hens with decreased Ca retention to a small extent and with reduced eggshell quality. These observations confirm that gastric acid secretion is of importance for CaCO3 solubilization but question its role as a prerequisite for intestinal Ca retention in chicks and even in hens fed on a high Ca diet.

Gastric acid secretion in the chicken: Effect of histamine H 2 antagonists and H +/K +-ATPase inhibitors on gastro-intestinal pH and of sexual maturity calcium carbonate level and particle size on proventricular H +/K + ATPase activity

1. 1. Cimetidine was more potent 4hr after a single injection of 25 or lOOmg/kg body wt in increasing gastric pH than other H 2 receptor antagonists, ranitidine and famotidine but was less efficient than H +/K +-ATPase inhibitors. Omeprazole rose proventricular and gizzard pH at a lower dose than SCH 28080 and Ro 18-5364 (30, 50 and 200 mg/kg body wt, respectively). 2. 2. Proventricular and gizzard pH values were maximal 1 and 4 hr after a single injection of 7.5 μmol/kg body wt omeprazole. Inhibition of acid secretion was maintained for 24 hr after an injection of 100 μmol/kg. 3. 3. H +/K +-ATPase activity in vitro was 10μimol P i/hr/mg protein in the microsomal fractions of the proventriculus. It was doubled by nigericine and inhibited by SCH 28080. However, western blots by high specific H +/K +-ATPase monoclonal antibody 95-A3 and 95–111 recognized a 42kDa band but hardly exhibited the specific 95 kDa band recognition. 4. 4. Chickens and immature pullets showed a higher H +/K + -ATPase activity than laying hens. Calcium level of the diet did not affect the enzyme activity but coarse particles of calcium fed to pullets or laying hens enhanced the H +/K +-ATPase activity when compared with ground particles.

The Effects of Particle Size and Origin of Calcium Carbonate on Performance and Ossification Characteristics in Broiler Chicks

The following physico-chemical characteristics of various calcium sources, differing in origin and particle size were determined: mineral composition, sieve and image analysis, apparent solubility (AS), surface area (SA), porous volume, specific gravity, and compressibility (C). The AS, SA, and C values were related more to the calcium particle size than to its origin and were higher in ground calcium sources. Calcium retention of seashells treated with phosphoric acid, oyster shells, and limestone using two particle sizes, ground or particulate, was assayed in 98 broiler chicks. Particulate marble was also tested in this experiment. Calcium retention expressed as a percentage of calcium ingestion was decreased when coarse particles of calcium were supplied in lieu of pulverized sources (40 versus 49%). An experiment with a 3 × 3 × 3 factorial arrangement of treatments were tested using 576 broiler chicks. Treatments included three calcium sources (phosphorus-treated shell, oyster shell, and marble), three particle sizes [ground (less than .15 mm), medium (.6 to 1.18 mm) and coarse (greater than 1.18 mm)] and three levels of calcium (.5, .7, and .9%) with ground limestone as a reference. Performance, tibial morphometry, breaking strength variables, and ash content were measured at 4wk of age. Weight gain and feed conversion were ameliorated with ground particles of calcium. Cortical thickness, length of the tibia, stiffness, stress, and tibia ash were diminished when coarse particles of calcium were incorporated in the diets. Conversely, the origin of the calcium source hardly affected these criteria. Additionally, the incorporation of phosphorus-treated shells was assayed in 112 broiler chicks. Coarse particles decreased calcium retention. Consequently, ultimate stress, the modulus of elasticity, and stress were impaired. It is concluded that differences in utilization of calcium carbonate sources by the broiler chick is primarily a result of particle size rather than origin. Ground particles of calcium (pan to .15 mm) significantly improves performance and tibial ossification characteristics in broiler chicks.

Calcium hydroxide and calcium carbonate particle size effects on reactivity with sulfur dioxide

The effect of in situ calcium hydroxide [Ca(OH 2)] and calcium carbonate (CaCO 3) sorbent particle size upon reactivity with 3000 ppm sulfur dioxide (SO 2) in an 1100°C drop-tube furnace was measured by on-line collection of the reacted sorbent with a particle cascade impactor. Significant agglomeration occurred for the hydroxides, while little was apparent for the carbonate. Reactivity of all sorbent particles increases as the measured particle diameter decreases such that conversion is inversely related to diameter to the 0.22–0.32 power. For these sorbents, Ca(OH) 2 particles had greater reactivity than the similarly sized CaCO 3 sorbent.

各種炭酸カルシウム顔料による塗工紙表面の平滑性 三次元からの一考察

Calcium carbonates, which contribute the improvement of the optical properties and printabilities to paper, are generally used for paper coating pigments as well as kaolin clay.In this paper, the surface smoothness of coated paper with various calcium carbonates have been evaluated by two instruments.One is the instrument which measures the value in terms of Rp (printing roughness). The Rp value determined by the optical contact method, represents the surface smoothness of paper in contact with prism surface under the pressure.The other is the instrument which measures the three dimensional roughness by stylus method.The results obtained with the two instruments represent that coated paper with cubical calcium carbonate having 11.5m2/g BET specific surface area showed the highest smoothness among them, including those coated with kaolin clay which was prepared for comparison purpose. Rp value has the positive correlation with the average particle size of calcium carbonate, and the gloss of coated paper.

Significance of Iron Oxides and Calcium Carbonate Particle Size in Phosphate Sorption by Calcareous Soils

AbstractThough many soil components are involved in reactions whereby soluble fertilizer P is converted to less soluble and therefore less available forms, the relative influence of each phase in this process is not clearly defined. While both crystalline and amorphous Fe oxides readily react with P in noncalcareous soils, the contribution of these forms to P sorption in calcareous soils has received little attention. Thus, in this study, samples of 20 mainly calcareous Lebanese soils, ranging widely in relevant properties, were equilibrated for 6 d with 25 mL P solutions ranging from 12.5 to 62.5 mg kg−1. The data did not conform to the conventional Langmuir isotherm. Correlations and regression coefficients with actual P rentention from solution indicated an involvement of oxalate Fe, but there was no effect of CaCO3 particle size. Removal of Fe prior to equilibration had an inconsistent effect on P retention. The P behavior of calcareous soils may be modified by Fe oxides in such soils.

Effect of calcium carbonate and paraffin wax levels on the performance of PVC pipe

AbstractPVC pipe compounds typically contain varying amounts and types of calcium carbonates, paraffin waxes, and other ingredients such as stabilizers, titanium dioxide, calcium stearate, and processing aids. The purpose of this paper is to study the effect of calcium carbonate particle size, coating, and usage level on the properties of PVC pipe. In addition, the effects of varying the paraffin wax level and melt temperature will be explored. The paper describes these effects as a function of both impact strength and stress‐rupture regression. Based on these results, a series of recommendations on type and usage level of the calcium carbonates and paraffin waxes, and processing conditions for the compound will be developed for use in guiding the pipe manufacturer towards producing PVC pipe that is both performance‐oriented and cost‐effective.

Reduction of notch sensitivity and improvement in low‐temperature impact strength of PVC

AbstractPVC is a notch‐sensitive polymer. The drop weight impact strength is also lost dramatically below 0°C. This requires special formulation considerations for critical applications. The general trend is to use polymeric impact modifiers, which are rubbery, graft polymers or blends of both hard and rubbery materials. This is achieved with some sacrifice in flexural modulus and formulation economics. A recent study conducted to relate calcium carbonate particle size with notched Izod and low‐temperature drop weight impact strength has shown that the stearate‐coated Ultrafine precipitated calcium carbonate (0.07 μ), at 15 phr loading, substantially improves both properties without sacrifice in flexural modulus. The formulation cost is also favorable. It is hypothesized that improvement in the above properties is primarily due to uniform stress distribution and lack of defect structure, as observed with coarse fillers. Surprisingly, the optimum‐particle‐size, coated, precipitated calacium carbonates also improved the Ultraviolet light stability of the PVC.

Ammonia Volatilization as Influenced by Calcium Carbonate Particle Size and Iron Oxides

Ammonia Volatilization as Influenced by Calcium Carbonate Particle Size and Iron Oxides