Grinding Intensity Research Articles

Mechanical Activation of CaO‐Based Adsorbents for CO2 Capture

The reversible cycling of CaO adsorbents to CaCO(3) for high-temperature CO(2) capture is substantially improved by mechanical treatment. The mechanical milling intensity and conditions of grinding (e.g., wet vs. dry, planetary vs. vibratory milling) were determined to be the main factors that control the effectiveness of the mechanochemical synthesis to enhance the recycling stability of the sorbents prepared. In addition, MgO was used as an example of an inert binder to help mitigate CaCO(3) sintering. Wet planetary milling of MgO into CaCO(3) allowed efficient particle size reduction and the effective dispersion of MgO throughout the particles. Wet planetary milling yielded the most stable sorbents during 50 cycles of carbonation-calcination.

Effect of particle size on the enzymatic hydrolysis of polysaccharides from ultrafine lignocellulose particles

The efficiency of the enzymatic hydrolysis of wood polysaccharides ground into ultrafine particles (UFPs) has been investigated. The content of reducing sugars (RS's) in powdered raw materials and the yield of sugars during enzymatic hydrolysis have been shown to depend on the particle size. Laser interference microscopy and dynamic light scattering studies have shown that increasing the grinding time from 20 to 40 min resulted in the formation of particles ranging from 2 to 200 nm in size. Enzymatic hydrolyzates of UFPs mostly contained glucose and galactose. The grinding intensity (mill rotation rate) and time had a significant effect on the extent of the enzymatic hydrolysis of wood.

Research and Development of a New Laboratory Mill

This paper studies a new mill, which is developed particularly for the laboratory scale, with respect to the problems of low efficiency and bad adaptability of mills commonly used in laboratories. The paper briefly introduces the machinery construction, working principle, performance characteristics and grinding test methods. The main shaft of the mill is driven to rotate by the motor drive variable-speed system (speed control system), it could be equipped with cylinders of different volumes, the working speed and grinding intensity are adjustable; running cycle time is automatically controlled and adjustable, which eliminate the adverse effects caused by manual control errors. The results show that this machine could change the dosage scale of test materials in a large range, facilitate the grinding materials tests of different ores and different scales, and greatly improve the test efficiency and equipment’s adaptability.

Influence of ultrafine wet grinding on pozzolanic activityof submicrometre sugar cane bagasse ash

Sugar cane bagasse ash is an important byproduct of sugar and alcohol production.This residual material requires only grinding and classification in orderto achieve adequate fineness and homogeneity to be used as pozzolanic admixturein concrete. In this study, submicrometre ashes were produced from wet grindingusing a planetary ball mill. Measurements of the pozzolanic activity of theashes with cement and lime were carried using mechanical methods based onthe compressive strength of mortars. It was observed that the pozzolanic activityof submicrometre ashes is inversely correlated to its particle size. Moreover,it was demonstrated that the grinding intensity clearly increased the sugarcane bagasse ash reactivity.

Surface modification of wollastonite by the mechano-activated method and its properties

Surface modification of wollastonite particles using titanate as a modification agent incorporated by simultaneous wet ultra-fine grinding in a laboratory stirred mill was investigated. The physical, physic-chemical and application properties of the modified wollastonite were measured and evaluated. The results showed that grinding intensity markedly influences the modification effect because of the mechano chemical effect. The hydrophilic surface of wollastonite was turned into a hydrophobic one after modification. The interaction between titanate and wollastonite under wet grinding circumstances was studied. It was suggested that physical adsorption and chemical adsorption of titanate coexisted on the wollastonite surface. The mechanical properties of polyethylene (PE) filled with the modified wollastonite powder were markedly improved.

Reaction between Carbon Dioxide and Mechanically Activated Metal Powder

A fundamental study on the reaction between CO2 and mechanically activated metal powders has been conducted. In this research, the behavior and mechanism of CO2 reaction under various grinding conditions were investigated to fix and reduce CO2. The powder used was placed inside a grinding vessel, and was ground together with the SUJ2 balls in CO2 atmosphere. It was found that only the adsorption of CO2 gas on the ground samples was observed, whereas the decomposition of CO2 was not occurred. The CO2 adsorption increased proportionally with the increase in the grinding speed, weight of sample and number of SUJ2 balls. Furthermore, the CO2 adsorption increased with the decrease in the standard free energy of formation of each metal oxide. The morphology of the sample observed by SEM showed that the samples were not crushed into finer particles, but were only grazed on the sample’s surface. Therefore, it can be said that the CO2 can be adsorbed on the mechanically activated samples by using the centrifugal type ball mill, but in order to enhance the amount of CO2 adsorption, another type of machine with higher grinding intensity should be considered.

How to assess particle size distribution in diets for pigs?

It is well known that finely ground diets pose the risk of gastric ulcers, whereas coarsely ground diets reduce Salmonella prevalence in pigs as observed in epidemiological, experimental and field studies with piglets or fattening pigs. Therefore, grinding intensity of components in pig diets came on debate again. The aim of this study was to standardize the measurement of grinding intensity, to recognize influences on particle size distribution in diets, and to monitor the “structure” (particle size) in commercial diets for piglets, fattening pigs and sows (in total n = 350). Complete diets of different physical forms (ground, pelleted, crumbled) were analysed by dry and/or wet sieve analysis. The distribution of particle sizes was affected by the type of corn (with or without spelt), post-grinding treatment as well as the method of sieving (dry/wet). While monitoring commercial feeds the highest grinding intensity could be observed in complete diets for piglets and fattening pigs, whereas feeds for sows contained more coarsely ground particles.

Effects of diet's physical form (grinding intensity; meal/pellets) on morphological and histological parameters (e.g. ratio of neutral to acid mucins) of the gastrointestinal tract in weaned piglets

Feeding coarsely ground meal diets has prophylactic effects regarding gastric ulcers and Salmonella infections in pigs. That gave the onset to study the effects of two diets only differing in the physical form (grinding intensity; meal/pellets) in terms of morphological parameters and carbohydrate histochemistry of the intestinal wall. There could not be found any influence of the diet regarding the morphometric character of the epithelial surface in the gastrointestinal tract (GIT). In contrast, PAS (neutral mucins) and AB pH 2.5 (acid mucins) staining of the gut wall revealed significant differences between the two treatments. The most considerable effect was found within the ratio of neutral to acid mucins, while the coarse meal diet resulted in a significant higher proportion of acid mucins what probably has an impact on the adherence capability of bacteria.

Impact of diets' physical form (particle size; meal/pelleted) on the stomach content (dry matter content, pH, chloride concentration) of pigs

Pars nonglandularis (PN) is the main affected area of gastric ulcers in pigs. Several factors are discussed to affect integrity of porcine gastric mucosa, but special emphasis is given to physical form of the feed. A total of 26 pigs (bw: 36.4 ± 10.5 kg) were housed individually and test diets were fed ad libitum for 3 days. The four diets used in this study were identical in botanical and chemical composition, but differed in grinding intensity (fine/coarse) and physical form (pelleted/meal). On day 3, animals were sacrificed 6 hours after free access to feed (after an overnight fast). The stomach was withdrawn in toto and frozen immediately at − 80 °C. A sagittal cut was made and samples of the frozen gastric content were taken from 15 standardized localisations to determine dry matter content, pH and chloride (Cl) concentration using standard methods. Physical form of diets noticeably affected quality and composition of stomach content. Marked effects were found in the PN. The finely ground and pelleted diet (FP) resulted in a more liquid chyme and a significantly higher Cl-concentration at PN in comparison to the results observed after feeding the unpelleted diets (CM/FM). There was no distinct pH gradient between the regions after feeding FP. However, the coarsely ground meal (CM) caused highest pH values at PN and low pH values at fundus region. Cl-concentrations at PN were markedly lower when pigs were fed the unpelleted diets (CM/FM). In pigs fed FP a significantly higher Cl-secretion rate of the upper gastrointestinal tract was found. Therefore this study shows clearly effects of grinding intensity and physical form of the diet on composition and quality of gastric chyme within the different regions of porcine stomach. The relatively high pH at PN after feeding the FP indicates that pH presumably is not the key factor for development of gastric ulcers in pigs at PN.

Effect of grinding intensity and crude fibre content of the feed on growth performance and gastric mucosa integrity of growing –finishing pigs

The influence of the interaction between crude fibre content and grinding intensity of the diet on performance results and gastric mucosa integrity was studied in a 2 × 2 factorial trial. Therefore, the 4 treatments were: low fibre-finely ground, low fibre-coarsely ground, high fibre-finely ground and high fibre-coarsely ground. Ninety-six pigs were allotted to 16 pens, with 3 barrows and 3 gilts per pen. Each pen was randomly assigned to 1 out of 4 treatments, leading to 4 pens per treatment. The low fibre diet contained 4% crude fibre, and the high fibre diet 9%. The higher fibre content was achieved by including beet pulp and alfalfa in the diet and using soybean meal with a lower protein content. The finely ground feed was produced using a hammermill with a screen of 1.5 mm for grinding the ingredients, the coarsely ground was produced with a screen of 6 mm. Three-phase feeding was applied and within each phase, diets were formulated to be identical in net energy, crude protein, digestible lysine, methionine + cystine, threonine and tryptophan content. No significant interaction between grinding intensity and crude fibre content on performance was observed, although, during the second feeding phase (40-70 kg), a small effect on feed intake was noticed. Performance results were not significantly affected by grinding intensity. While crude fibre content did not affect the growth performance during the first or second feeding phase, an adverse effect on feed conversion ratio was noticed during the third feeding phase. Possibly, the net energy content of the high fibre diet was overestimated in the third phase. Macroscopic lesion scores of the pars oesophagea of the stomach were not affected by grinding intensity or crude fibre content exclusively. However, animals on the coarsely ground high fibre diet showed lower macroscopic lesion scores, indicating a synergistic effect of grinding intensity and crude fibre content on preventing lesions in the gastric mucosa.

The energy intensity analysis of the diamond-spark grinding of the WolKar nanostructural hard alloy

The problems of machinability of the WolKar new nanostructural hard alloy have been studied by analyzing a specific energy intensity of the diamond-spark grinding. It has been shown that despite the somewhat higher energy intensity of grinding the WolKar alloy as compared with grinding the WC-6Co alloy, the total technological net cost of using the WolKar alloy is essentially lower as tools sharpened by it exhibit a higher wear resistance.

Effects of dietary additives (potassium diformate/organic acids) as well as influences of grinding intensity (coarse/fine) of diets for weaned piglets experimentally infected with Salmonella Derby or Escherichia coli

The aim of this study was to examine whether and to what extent the addition of potassium diformate (pdf) or free organic acids (fpa) to the diet and the grinding intensity might affect the course of infection and the passage of orally applied Salmonella and Escherichia coli in pigs. Experiments were carried out using 80 reared piglets allotted to four groups. Pigs were fed pelleted diets ad libitum (except during a 15 h feed-withholding-period before infection). The control diet contained finely ground cereals (2 mm screen). To two test diets (also finely ground) 1.2% pdf, 0.9% organic acids (75% formic and 25% propionic acid, fpa) respectively were added. The fourth diet (without acids) was based on coarsely ground cereals (6-mm screen). After experimental infection alternately with S. Derby or E. coli, the course of infection was examined (rectal swab technique). Pigs were sacrificed 4-5 h after a further oral application of approximately 10(9)-10(10) CFU S. Derby or E. coli to determine the counts of Salmonella or E. coli in chyme (classical culture methods). Adding pdf or fpa to the diet led to reduced Salmonella shedding and resulted in significantly lower counts of Salmonella and E. coli in the stomach content indicating an improved efficacy of the stomach barrier. In the distal parts of the digestive tract, the effect was less obvious concerning counts of E. coli, whereas counts of Salmonella were reduced markedly as well. The diet based on coarsely ground cereals failed to demonstrate positive effects concerning infection and passage of orally applied bacteria as well, but this diet was also pelleted and showed unintentionally, comparable amounts of fine particles. Results obtained in this study allow the recommendation of using pdf or organic acids as additives when dietary measures against Salmonella or E. coli in pigs are required.

Integrity of gastric mucosa in reared piglets – effects of physical form of diets (meal/pellets), pre‐processing grinding (coarse/fine) and addition of lignocellulose (0/2.5 %)

The aim of the present study was to investigate the potential effects of different particle fractions in non-pelleted (meal) and pelleted diets on the development of pre-ulcerative gastric alterations. Furthermore, the effect of increased crude fibre supply (lignocellulose) on the integrity of gastric mucosa were investigated. For that purpose, 49 piglets were divided into eight feeding groups and fed pelleted diets differing in grinding intensity (very coarse/coarse/fine/very fine) and addition of lignocellulose (0/2.5%) for 6 weeks. A coarsely ground meal was used as control diet. Mucosal integrity of the pars non-glandularis was characterised by macroscopical and histological score and basal epithelial conductance. Feed structure was assessed by sieve analysis (wet/dry). The use of coarsely ground meal (25% >2 mm, 29% <0.4 mm) had almost no negative effects on the gastric wall: three of seven pigs had slight histological and none had macroscopical lesions. Irrespective of the original grinding intensity before pelleting, offering pelleted diets led to mucosal changes similar in severity (one out of seven pigs fed coarsely ground and pelleted diets had no macroscopical alterations, whereas all pigs fed finely ground and pelleted diets showed altered tissues). Increasing the proportion of coarse particles in the pellet (from 25 to 29% >2 mm) did not show any ulceroprotective effect. An increase of crude fibre content (42-54 g/kg dm) by adding lignocellulose did not result in a decreased ulcerogenity. Unpelleted diets are recommended as more favourable for alleviating the problem of gastric ulcers in pigs as the pelleting process is equal to a secondary grinding process. According to our results, an upper level of fine particles seems to be reasonable (a minimum level of coarse particles is not ulceroprotective). In this study, an amount of 30% <0.4 mm resulted in higher risks for ulcerations.

Effects of Soil Sample Grinding Intensity on Carbon Determination by High‐Temperature Combustion

Recently, many studies related to carbon (C) sequestration by soils have been reported. However, little information has been reported related to the need for and effects of grinding soils on C analysis by high‐temperature combustion. We studied the effects of grinding five glacially derived soils of varying textural composition and organic matter content to 2‐mm, 1‐mm, 0.5‐mm, 0.25‐mm, and 0.15‐mm particle sizes on the measurement of total, inorganic, and organic C content using a high‐temperature combustion technique. Medium‐textured soils showed significantly higher total and organic C values for the 2‐, 1‐, and 0.5‐mm particle sizes than for the 0.25‐ and 0.15‐mm particle sizes compared to soils that were high in sand or clay. Grinding did not appear to affect inorganic C values. Grinding the soils to 0.15 mm, in all cases, greatly reduced the variability of C values by as much as two‐ to six‐fold when compared to 2‐mm soils. We recommend that soils be ground to pass a 0.15‐mm (100‐mesh) screen prior to C analysis by high‐temperature combustion.

Lower grinding intensity of cereals for dietetic effects in piglets?

Abstract The grinding intensity of cereals as ingredients of pelleted diets has various effects on pigs' health and performance. Feeding a coarsely ground diet (62.2% of particles > 1 mm; 10%

Effects of mechanical activation on the reduction behavior of hematite concentrate

The effect of mechanical activation on the reduction behavior of a hematite concentrate has been examined using a combination of simultaneous thermal analysis (STA), X-ray diffraction (XRD), scanning electron microscope (SEM) analysis, and laser diffraction. The samples were activated in vibratory and planetary mills. Differential thermal analysis (DTA) and thermogravimetric (TG) analysis revealed that reduction of mechanically activated and initial hematite proceeds stepwise (Fe 2O 3 → Fe 3O 4 → Fe). The hydrogen reduction of mechanically activated samples initiates at low temperatures compared with the initial sample. The beginning temperature (onset) of the reduction decreases from 421 °C in the initial sample to 330 °C in the mechanically activated sample, depending on the grinding intensity. Further, the reduction of hematite to magnetite in the activated samples is more pronounced due to mechanical activation. At low temperatures, the activated samples give a higher degree of conversion than the initial samples regardless of which milling device is used. Hematite reduces completely to iron metal. A comparison of mill-type effect based on stress energy (specific grinding work) suggests that the mill-type effect is confined by a stress energy of 4300 kJ/kg. After releasing 4300 kJ/kg energy, mechanical activation by the planetary mill brings about a larger decrease in onset temperature and a slightly higher degree of conversion at lower temperatures than does activation by the vibratory mill for a given stress energy. A direct relationship between the reaction characters at lower temperatures and structure sensitivity character (S/X) and stored energy can be identified after releasing 4300 kJ/kg energy. However, partial sintering of material at higher temperatures during the reduction of the mechanically activated hematite became active, and the effects of disordering of the hematite structure vanished and subsequently the reduction reaction was retarded.

Phase Transformations Induced by Grinding: What is Revealed by Molecular Materials

AbstractThe purpose of this paper is to show some examples of phase transformations induced by grinding molecular materials. These materials are considered because they are extremely sensitive to external disturbances and are generally very good glass formers. This allows investigating more easily a broad range of the parameters which are open to influence the nature of the end product namely the temperature and intensity of grinding. Such an investigation has also a practical interest in pharmaceutical science. It is shown that the position of the grinding temperature with regard to the glass transition temperature of the compound is a key parameter. Comparison of the effects of temperature and intensity of grinding demonstrates that the driven material concept offers a framework to rationalize all the observed transformations.

Fine Grinding and Air Classification of Field Pea

ABSTRACTField pea has ≈23% protein, 48% starch, 8% sugars, 4% lipids, 7% crude fiber, and 3% ash. Pin milling at 1 × 14,000, 3 × 14,000, 9 × 14,000, and 12 × 14,000 rpm followed by air classification according to particle size resulted in fine fractions (&lt;18 μm) with high protein content and coarser fractions (&gt;18 μm) with high starch content. The yield of the high protein fraction increased with the intensity of grinding before air classification. The starch content of the high starch fraction increased with the intensity of grinding and subsequent air classification. Both whole pea and dehulled pea responded well to fine grinding and air classification, and the dehulled pea gave higher protein content and higher starch content than the corresponding fraction from whole pea. The protein fraction had high lysine content and met all the amino acid requirements of the World Health Organization for children older than two years and adults.

On-line determination of particle size during fine grinding based on luminescence properties of solids

Luminescence effect of particle surface stressed during milling operation was used to correlate the size of the ZnS/Cu particles. Both the amount of structural defects in solids and the area of newly created surface increase with the grinding intensity and time. The intensity ratio at two different wavelengths (400 and 500 nm) is found to be suitable for measurements of the particle size. This kind of measurement of particle size is insensitive to the particles aggregation and presence of abrasive substance in the suspension.

Protein enrichment of defatted salicornia meal by air classification

AbstractSalicornia bigelovii Torr. is a leafless, annual salt‐marsh plant. Previous investigators reported that the seed contained 26 to 33% oil, 30 to 33% protein, 5 to 7% fiber, and 5 to 7% ash. Hexane‐defatted salicornia meal was ground in a pin mill and separated by air classification into various fractions by particle size. The fine fractions were enriched in protein. The degree of protein enrichment and yield of fine fractions depended on the intensity of grinding. More intense grinding resulted in a higher yield of fine fractions with a smaller increase in protein content compared with less intensive grinding. The amino acid composition and proximate composition of the air‐classified fractions are compared with the starting material.