Rotor Mill Research Articles

Influence of sample preparation process on basic properties of biofuels

The characteristic properties of non-wood biomass used in combustion processes are monitored, such as water content, ash, volatile matter. Biomass is usually not homogenous and of suitable dimensions for these determinations. This is the reason for the necessary adjustment of samples for analysis. But modifying the samples may change their properties. In this publication, the influence of the grinding process in a rotor mill on the content of water, volatile matter and ash in non-wood biomass samples was studied. Samples of flax, Crambe abyssinica, amaranth and rye were analyzed. All analyses showed moisture loss from the sample during grinding and in the case of flax, the loss of volatile matter was observed. It means the rotor mill is suitable for sample preparation prior to analysis. But for oil plants it is necessary to choose another mill or adjustment method.

Simulation of the comminution process in a high-speed rotor mill based on the feed’s macroscopic material data

In this paper, we present a method that allows for the quick and efficient simulation of the comminution process in high-speed rotor mills. The method requires only the feed’s macroscopic material data and the geometry of the machine. Consisting of two stages, the method couples Computational Fluid Dynamics (CFD) with the Discrete Element Method (DEM) to obtain the collisional velocities and angles of a representative group of particles passing through the machine. Due to this coupling, any mill which relies on fluid forces acting on the ore particles can be simulated. After obtaining these values, the second stage commences wherein a single ore particle consisting of DEM elements collides against a rigid surface. The data obtained from this stage is then used to determine the minimum required working parameters of the chosen machine to achieve proper ore comminution. The proposed methodology was applied to analyse the novel concept of using beater mills for the comminution of copper ore.

Carotenoid stability and aroma retention during the post-harvest storage of biofortified maize.

BACKGROUNDMaize varieties that are rich in carotenoids have been developed to combat vitamin A deficiency in Sub‐Saharan Africa. Unfortunately, after harvest, carotenoids degrade and off‐flavor volatiles develop, which affect nutrient intake and consumer acceptance. This study evaluated carotenoid retention and aroma compound stability in provitamin A biofortified maize, variety Pool 8A, as influenced by dry milling and storage in different packaging and temperature conditions.RESULTSThe lowest amount of total carotenoids was found in flour stored in laminated paper bags at 37 °C (only 16% retention after 180 days), attributable to the high storage temperature and oxygen permeability of the packaging material. No significant effect on carotenoid degradation was found for dry milling, either by rotor mill or freezer mill, but the formation of volatile compounds was significantly (P < 0.05) affected. Volatile compounds such as hexanal, 2‐pentylfuran, 1‐propanol, 2‐heptanone, butyrolactone, limonene, and hexanoic acid were found in different proportions after milling. The highest concentration of hexanal was in flour milled by rotor mill or freezer mill, and stored in laminated paper bags at 37 °C after 180 days, and the lowest concentrations were for flour in aluminium bags and double‐layered polyethylene bags stored at 4 °C.CONCLUSIONMaize flour stored in double‐layered polyethylene bags had the highest carotenoid retention and aroma stability. Importantly, the use of these bags is economically feasible in low‐income countries. Overall, our results show that effective control of storage conditions is crucial to prevent carotenoid loss and decrease off‐odor formation. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Mechanical Properties of Reactive Powder Concretes Produced Using Pumice Powder

We examined the applicability of the pumice aggregate on the concrete formed by considering the reactive powder concrete mixture ratios, for the rigid superstructure concrete road pavement and building construction. The natural pumice aggregate in fibrous and non-fibrous concrete samples was used in the production of concrete by fracturing in 0.1-0.6 mm dimensions in rotor mill. The concreted formed in this way is named after the pumice powder concrete (PPC). The PPC samples produced were taken 7 days as 20 °C standard water cure, 28 days as 20 °C standard cure and 9 different types of combined cures. The combined cures were applied different temperatures in different durations. PPC samples were subjected to some pressure and flexural tests at the end of the standard water and combined cures. The highest compressive and flexural strengths of PPC samples were obtained after the combined cures: 3 days in 20 °C as standard water curing + 2 days in 180 °C in drying-oven. The highest compressive strength of PPC samples without any fiber was found to be 47.27 MPa, as for the highest flexural strength, it is found to be 5.23 MPa, in the end of the study. The highest compressive strength of fibrous PPC samples was 51.12 MPa, while flexural strength was 6.57 MPa.

Investigation of impact of a crumb rubbergranulate addition on the asphalt mixtures resistanceto water and frost

The article presents the results of the tests of hot mix asphalt (HMA) modi-fi ed with the addition of crumb rubber granulate using the dry method. This modifi cation consisted in the applying of rubber granules into the aggregate mixture, replacing a 0/2 mm fraction of the basalt aggregate. The tests were carried out for the Asphalt Concrete to be used in binder course of a road pavement (AC16W 50/70). There were 5 types of HMA analyzed: without the addition of rubber granules as well as with 1% or 2% (in relation to the weight of the aggregate mix) of activated with a grain size up to 2 mm and non-activated rubber granules with the same grain size. The activation process was carried out using an electro-magnetic mill with a microwave generator, centrifugal rotor mill with supersonic speed and auxiliary equipment. For each analyzed mixture type, density, bulk density, air voids and resistance to water and frost were determined. On the basis of the research, it was observed that the addition of crumb rubber granules to HMA adversely affects the air voids content causing its increase. The addition of crumb rubber granulate also affects the resistance of HMA to water and frost, but the quantitative changes depend on the amount of added crumb rubber granulate.

CHEMICAL, GRANULOMETRIC AND TECHNOLOGICAL CHARACTERISTICS OF WHOLE FLOURS FROM COMMERCIAL CULTIVARS OF COWPEA

ABSTRACT Flour production through milling is an alternative for the cowpea processing, when the aim is to obtain a product with higher added value. The objective of this work was to determine the chemical composition, the granulometry, and evaluate the microbiological characteristics of whole-bean flours from five cowpea cultivars (BRS Cauamé, BRS Guariba, BRS Xiquexique, BRS Novaera and BRS Itaim). Cowpea beans were dried in a oven (Fanem, 320-SE) at 50 °C for 6 hours, milled in a cyclone-type rotor mill (Tecnal, TE-651/2) and, subsequently, in a pulverizer-type semi-industrial mill (Fritsch, Pulverisette 14) to obtain the flour. The flour centesimal composition, total energetic value, mineral content, granulometry, microbiological characteristics, and technological properties-flour water absorption and solubility in water-were analyzed. All analyzes were performed in triplicate and the results expressed in mean ± standard deviation. The means were compared by the Scott-Knott test (p ≤ 0.05). The flour centesimal composition presented (g per 100 g of flour): 7.13 to 10.33 of moisture, 2.06 to 3.65 of ashes, 1.53 g to 2.90 of lipids, 21.73 to 25.77 of proteins, and 58.08 to 64.02 of carbohydrate. The flours had on average 359.04 Kcal (100 g) and presented high iron, zinc, copper, manganese, phosphorus and magnesium contents. The whole-bean flours from the cultivars BRS Cauamé and BRS Xiquexique are sources of calcium. Regarding the microbiological characteristics, all flours are innocuous. The water absorption index were within 1.77 and 2.20 g g-1 and the water solubility index within 17 and 23%. All whole-bean flours had good nutritional, technological and microbiological characteristics, and thus potential for use in bakery products.

Collaborative study on the effect of grinding on the detection of bones from processed animal proteins in feed by light microscopy

ABSTRACTBone fragments are essential structures for the detection of processed animal proteins (PAPs) in feed by light microscopy for official controls according to Annex VI of European Union Regulation EC/152/2009. The preparation of samples submitted for analysis requires a grinding step to make them suitable for microscopic slide preparation and observation. However, there are no technical guidelines set down for this step despite the fact that it can lead to an increase in bone numbers due to fragmentation. This was demonstrated by an in-house study carried out by the Irish National Reference Laboratory (NRL) for animal protein detection. The present collaborative study investigated the possible effects of three different grinding conditions on the final result for a feed adulterated with 0.05 and 0.01% (w/w) of PAP. The microscopic analysis either combined or not with an Alizarin Red staining was carried out by 10 different laboratories. The results demonstrated that although a large variation in the numbers of bone fragments was noted, five of the six different grinding/staining combinations applied at two levels of PAP adulteration did not significantly (at p = 0.05) differ from one another. The only exception occurred when grinding the feed containing 0.05% of PAP with a rotor mill equipped with a 0.5-mm sieve and combined with a staining which resulted in a greater number of bone fragments by forced fragmentation. Overall, the impact of the grinding/staining combinations on the final results was shown to be negligible when considering the regulatory limit of detection (LOD) requirement for the method and the current rules of implementation of the light microscopic method. From a total of 180 analyses carried out on the feed matrix containing 0.05% of PAP no false-negative result was observed, and at a level of 0.01% PAP only 10 false-negative results occurred.

Effect of thermal processing on total polyphenol content in the grain of cowpea cultivars

Cowpea grain is noteworthy due to its functional properties, which are probably a result of the synergistic action of its nutrients and bioactive compounds. Since these compounds undergo the effects of thermal processing, the aim of the present study was to verify the influence of cooking on the total polyphenol content of the grain of cowpea cultivars. Samples were obtained from the experimental area of Embrapa Meio-Norte, located at 5°5’ S and 42°48’ W, at an altitude of 72 metres. Meal (0.5 mesh) resulting from the raw grain being ground in a cyclone rotor mill (Tecnal model TE-651/2-T), and cooked beans (with no maceration, at a bean to water ratio of 1:5 (w/v), cooked in a domestic pressure cooker (2 L) for 780 seconds) were stored in airtight containers under refrigeration (8 °C) for analysis, which was carried out in triplicate. Total phenolic content was determined by spectrophotometry (λ = 765 nm), using Folin-Ciocalteau reagent. The total phenolic content, mg GAE (gallic acid equivalent)/100g, in the raw grain of the BRS Marataoa, BR 17-Gurgueia, BRS Itaim, BRS Cauame and BRS Guariba cultivars was 295.23, 255.67, 132.32, 98.14 and 89.43 respectively. After cooking, the content was 405.87, 255.4, 161.71, 127.79 and 111.92 respectively, considering both grain and broth. This rise may have been the result of increased solubilisation and extraction of the compounds, due to the softening or rupture of the plant cells. It was concluded that, considering both grain and broth, the total phenolic content increased after cooking; the BRS Marataoa and BR 17-Gurgueia cultivars showed the highest levels.

Effects of mechanical activation on the parameters of talc quality for ceramics production – Chemometric approach

Talc is broadly used in the ceramic materials industry, either as a basic raw material, or as filler, due to its chemical inertia, fragmentation proneness, thermal stability, and refractoriness. The mechanical activation is frequently employed in the direct enhancement of talc properties, and thereby in the design of talc based composites with advanced performances. The differences in the set of the process parameters measured before and after talc activation via ultra-centrifugal mill Retsch ZM-1, and their influence on the grain-size distribution related characteristics have been investigated. The mechanical treatments are energetically unsustainable procedures, therefore the talc activation was optimized on basis of assessment of the process variables (number of rotor revolutions, current intensity, activation period, circumferential rotor speed and mill capacity) effect on the final quality of product parameters (mesh sizes, cumulative oversizes, average grain size, level of micronization kinetics, mesh size appropriate to 95% micronized product cumulative undersize and specific surface area). The activated product parameters in all experimental sequences were obtained by the analytical procedure based on Rosin-Rammler-Sperling equation. Response surface method, standard score analysis and principal component analysis were used as a means of the optimization. Developed models showed r2 values in the range of 0.714–0.908 and they were able to accurately predict quality parameters in a wide range of process parameters. Standard score analysis highlighted that the optimal sample was obtained using sieve mesh of 120 μm set of processing parameters (SS = 1.0). Multiple comparison tests revealed that the optimal variation in the processing parameters could reduce the negative effect of talc samples inherent properties on the final score and improve the activation procedure energetic and economic sustainability.

Effect of grinding methods and packaging materials on fenugreek and black pepper powder quality and quantity under normal storage conditions

Abstract: The effect of different grinding methods and packaging materials on qualities of fenugreek and black pepper powders was evaluated. Various parameters and their evaluation methods are as follows: change in colour determined using Chroma meter calorimeter, aroma and odour measured by sensory evaluation, and change in moisture measured using oven drying method. Packaging materials such as glass jar, steel jar, plastic jar, aluminum bag and poly bags were used for keeping ambient and cryogenically ground fenugreek and black pepper powders. Packed powders were stored in dry and cool places under ambient condition. Sensory evaluation revealed quality reduction in terms of colour, odour, flavour, aroma and acceptability for fenugreek and black pepper powder stored for a long term (6 months). However, glass jar and steel jar were found to be better containers for storing powders for longer storage period than other options. For practical applications, the present investigation on the deterioration behaviour of fenugreek and black pepper powder contributes to the design of a suitable grinder out of ball, hammer, rotor, and pin mill for spice grinding. The study also helps select a suitable packaging material or container to store spice powders. A method to assess the quality of stored powder and its deterioration with the storage time is provided. Keywords: quality deterioration, behaviour; aroma; cryogenic; ambient; packaging DOI: 10.3965/j.ijabe.20140704.012 Citation: Meghwal M, Goswami T K. Effect of different grinding methods and packaging materials on fenugreek and black pepper powder quality and quantity under normal storage conditions. Int J Agric & Biol Eng, 2014; 7(4): 106－113.

Comparative study on ambient and cryogenic grinding of fenugreek and black pepper seeds using rotor, ball, hammer and Pin mill

The suitability of a grinder based on their performance, fenugreek and black pepper seeds were ground under ambient and cryogenic grinding condition with the help of rotor, ball, hammer and pin mills. Rotor, hammer and pin mills were found to be good for small scale grinding at a feed rate of 22.5gmin−1 under ambient conditions and at 24.5gmin−1 for cryogenic grinding (continuous process) whereas the ball mill could be used for a lower feed rate of 1.56gmin−1 under ambient grinding; and 2.08gmin−1 under cryogenic grinding (batch processes). Time taken in grinding an equal amount of sample to a definite size in various grinders was found to be in the order: ball mill>rotor mill>pin mill>hammer mill; order of feed rate: hammer mill>rotor mill>pin mill>ball mill; order of power consumptions: pin mill>hammer mill>rotor mill>ball mill; and order of surface area created: rotor mill>hammer mill>pin mill>ball mill. Out of the above selected grinders, the rotor mill was found to be the most suitable for grinding fenugreek and black pepper spices. Power consumption was found to be increasing with an increasing specific surface area. This study will be useful for food process industries while considering spice-grinding applications; and also in academic field to understand suitability of grinders, their grinding mechanism.

Analysis of total copper, cadmium and lead in refuse-derived fuels (RDF): study on analytical errors using synthetic samples

Components with extraordinarily high analyte contents, for example copper metal from wires or plastics stabilized with heavy metal compounds, are presumed to be a crucial source of errors in refuse-derived fuel (RDF) analysis. In order to study the error generation of those 'analyte carrier components', synthetic samples spiked with defined amounts of carrier materials were mixed, milled in a high speed rotor mill to particle sizes <1 mm, <0.5 mm and <0.2 mm, respectively, and analyzed repeatedly. Copper (Cu) metal and brass were used as Cu carriers, three kinds of polyvinylchloride (PVC) materials as lead (Pb) and cadmium (Cd) carriers, and paper and polyethylene as bulk components. In most cases, samples <0.2 mm delivered good recovery rates (rec), and low or moderate relative standard deviations (rsd), i.e. metallic Cu 87-91% rec, 14-35% rsd, Cd from flexible PVC yellow 90-92% rec, 8-10% rsd and Pb from rigid PVC 92-96% rec, 3-4% rsd. Cu from brass was overestimated (138-150% rec, 13-42% rsd), Cd from flexible PVC grey underestimated (72-75% rec, 4-7% rsd) in <0.2 mm samples. Samples <0.5 mm and <1 mm spiked with Cu or brass produced errors of up to 220% rsd (<0.5 mm) and 370% rsd (<1 mm). In the case of Pb from rigid PVC, poor recoveries (54-75%) were observed in spite of moderate variations (rsd 11-29%). In conclusion, time-consuming milling to <0.2 mm can reduce variation to acceptable levels, even given the presence of analyte carrier materials. Yet, the sources of systematic errors observed (likely segregation effects) remain uncertain.

Bran characteristics and wheat performance in whole wheat bread

SummaryThe effect of the composition and physical properties of bran from four wheat samples from different cultivars was determined in whole wheat bread. High specific volume of whole wheat bread was correlated (r2 = 0.8275) with strong mechanical properties (low friability) of the bran of wheat cultivars, as determined by sizing (over 425 μm) of bran particles after grinding with a rotor mill. Fibre content and composition of insoluble fibre (hemicellulose, cellulose and lignin) in the bran fraction had a non‐significant (P &gt; 0.05) effect on the performance of wheat cultivars in whole wheat bread. Water absorption of bran was correlated (r2 = 0.9532) with its insoluble fibre content. Based on data obtained with white flour, it was not possible to estimate the baking potential of wheat cultivars in whole wheat bread.

A Comparative Study of Mechanical Property in Al-8Fe-2Mo-2V-1Zr Bulk Alloys Fabricated from an Atomized Powder and a Melt Spun Ribbon

Al-8Fe-2Mo-2V-1Zr alloy powders were prepared by gas atomization and melt spinning method. In melt spinning technique, melt spun ribbons were pulverized by a speed rotor mill to make a powder shape. In order to produce a bulk form, powders were canned and hot extruded in the extrusion ratio of 25 to 1 at 693K. For the gas atomization and hot extrusion processed bulk material, equiaxed grains with the average size of 400 nm and finely distributed dispersoids with their particle sizes ranging from 50nm to 200nm were observed to display a characteristic nano-structured feature over the entire region. For the melt spun and hot extrusion processed alloy, a refined microstructural feature consisting of equiaxed grains with the average size of 200 nm and fine dispersoids with their particle sizes under 50 nm appeared to exhibit a difference in microstructure. Yield strength of the latter alloy was higher than that for the former alloy up to elevated temperatures. The maximum yield strength was measured to about 800 MPa at room temperature for the latter alloy.

철계 비정질 합금 분말코아의 자기적 특성에 미치는 분말 제조방식의 영향

철계 비정질 합금 리본을 분쇄한 뒤 상온 압축성형을 통하여 분말코아를 제조할 때 로터밀과 볼밀의 두 가지 분말제조 공정을 사용하여 만든 분말의 형상을 관찰하고, 또 이들을 이용한 분말코아의 자기적 및 전기적 특성과 미세구조를 조사하였다. 로터밀을 사용한 경우 실효투자율의 크기는 볼 밀링한 경우보다 낮았으나 이의 주파수 의존성 및 품질계수는 볼밀의 경우보다 우수하였으며 자심손실 또한 더 작았다. 한편 로터밀을 사용하여 만든 분말은 크기가 균일하고 가장자리는 강한 전단가공을 받아 완만한 곡선을 지닌 등축형을 이루고 있는 반면 볼밀을 사용한 경우는 크기가 상대적으로 불규칙하면서 작은 분말이 많고 가장자리는 날카로운 형상을 하고 있었다. 로터밀로 만든 분말코아의 낮은 투자율은 밀링시 심한 전단에 의해 발생하는 큰 내부응력의 축적에 기인하는 것으로 보여진다. 한편 로터 밀링을 통해 만든 분말코아의 경우 투자율은 상대적으로 낮지만 전기저항의 측정 및 미세구조의 관찰로부터 보다 양호한 절연상태가 확보되어 높은 주파수에 이르기까지 투자율이 유지되면서 적은 자심손실이 얻어진 것으로 판단되었다. 분말코아의 자기적 안정성을 나타내는 직류중첩특성 또한 로터밀의 경우가 볼 밀링한 경우보다 우수하였다. In the fabrication process of Fe-based amorphous alloy powder cores by pulverization of the melt-spun ribbons and cold compaction, the effects of powder preparation method on the magnetic & electric properties, powder shapes and microstructure of cores have been investigated. The powder cores made by using rotor mill showed low effective permeability as compared to the cores prepared by ball milling. However the frequency dependence and quality factor properties were superior in the case of rotor-milling. Further the powders prepared by rotor mill had homogeneous and round shapes through strong shearing in the sieve ring, while the ball milled powders were inhomogeneous and relatively small. The lower permeability of the powder cores fabricated with rotor mill was considered to be due to the high internal stress occurred by very intensive shearing. Moreover the powder cores produced by rotor-milling showed lower core loss and good frequency dependence of effective permeability possibly due to the higher electrical insulation between magnetic particles. The dc bias property of the powder cores made by rotor-milling was better than the one by ball-milling.

Magnetic properties of nanocrystalline Fe73.5Cu1Nb3Si15.5B7 alloy powder cores with different particle size prepared by rotor mill

The relationship between magnetic properties and particle size in nanocrystalline Fe 73.5 Cu 1 Nb 3 Si 15.5 B 7 alloy powder cores prepared by using a rotor mill and cold press was investigated. The powder cores having large particles of 250-850 pm exhibited stable permeability of 100 up to 500 kHz, a maximum level of 50 of quality factor at 50 kHz, and 360 mW/cm 3 core loss at 50 kHz and 0.1 T of induction. However the powder cores with small particles lower than 250 pm showed low permeability and high core loss as compared to large particle cores. Additionally the large particle cores have homogeneous and well-aligned microstructure leading to high density state. On the contrary, the powder cores composed of small magnetic particles showed irregular and complex distribution of magnetic powders, and the density seems rather low. The enhanced magnetic properties of powder cores with large particles were attributed to the particle size dependence of compressed state of powders.

Dispersion of tungsten carbide particles in silver-nickel alloy powder by elliptical rotor mill: M.Satoh et al. (Osaka Prefecture University, Sakai, Japan.) J. Jpn Soc. Powder Powder Metall., vol 44, no 6, 1997, 618–621. (In Japanese.)

Dispersion of tungsten carbide particles in silver-nickel alloy powder by elliptical rotor mill: M.Satoh et al. (Osaka Prefecture University, Sakai, Japan.) J. Jpn Soc. Powder Powder Metall., vol 44, no 6, 1997, 618–621. (In Japanese.)

Effect of Enzymatic Treatment on the Morphology of Cotton Fibers Shattered by Dry Process.

Cotton fibers were shattered by a rotor mill with different sieve meshes and then treated with cellulase to obtain cotton cellulosic powder which could be potentially new material resource. In the initial stage of the enzymatic treatment, the nap formed on the fiber surface during the mechanical shattering was exclusively hydrolyzed. Therefore, the fiber surface of the shattered fiber became smooth, and the weight loss became much larger in the treatment of the shattered fibers than in the treatment of the original cotton fiber. When the treatment time was increased, the fiber length became shorter with many cracks formed inside the fiber. Wide angle X-ray scattering of the enzyme-treated fibers revealed that the crystallinity increased in the initial stage of the treatment, but became constant in the later stage. The specific surfacc area and micropore volume of the fibers sharply decreased in the beginning of the enzymatic treatment, while they increased in the later stage with increasing treatment time. The specific surface area reached a plateau after 50h of treatment with the micropore volume decreasing.

Grinding and dispersing latnen clay in a Rotor mill

Grinding and dispersing latnen clay in a Rotor mill

Rapid rotor mill for ceramic industry

Rapid rotor mill for ceramic industry