Reports applicativi
Macinazione (47)
Silicio per l’energia solare
I semiconduttori sono utilizzati per una grande varietà di applicazioni elettroniche, come circuiti integrati (microprocessori, microcontrollori, ecc.) rilevatori ottici e sorgenti di radiazioni (es. emettitori di luce), ma in modo particolare per i fotovoltaici, tramite i quali l’energia solare viene trasformata in potenza elettrica. Per la maggior parte delle applicazioni, il silicio è il materiale semiconduttore scelto.
Plastica – un materiale con molte variazioni
Grazie alla varietà quasi illimitata di materie plastiche, i loro campi di applicazione sono vasti. Abbreviazioni come PE, PET, PC, PP, PBT o ABS non descrivono solamente un semplice materiale, ma un’intera classe di prodotti con molte caratteristiche differenti. A seconda della destinazione d’uso, la plastica deve essere, per esempio, resistente agli urti, a prova di rottura, resistente al calore o resistente ai solventi.
Energia rinnovabile
Residui di legno dalle lavorazioni forestali e dalla lavorazione del legno sono solitamente trasformati in trucioli di legno. Questi possono essere utilizzati in modo diverso, in base al tipo di legno, alla corteccia, all’umidità residua, ad esempio come materia prima per pannelli truciolari o come substrato per la coltivazione di funghi. La maggior parte, comunque, viene utilizzata per la produzione di energia. La qualità del legno cippato può variare notevolmente, a seconda della sua origine e condizione. Il commercio e l’industria sono interessati alla percentuale di materia secca e al potere calorifico del legno cippato, così come il valore del prezzo dipende dal contenuto di acqua nel prodotto. Con il risultato dell’analisi che rappresenta un importante fattore economico, anche la preparazione del campione in modo rappresentativo e riproducibile ottiene importanza
Il più puro possibile
Anche se la macinazione viene svolta in condizioni ideali, gli stress meccanici che il campione esercita sulla superficie degli strumenti di macinazione può causare abrasione. Tuttavia, selezionando un mulino e degli accessori adatti è possibile minimizzare questo effetto. Se il campione deve essere macinato a pezzature inferiori ai 100 microns, le forti forze meccaniche richieste aumentano l’abrasione.
Le barrette di cereali sono veramente sane?
I produttori alimentari spesso promuovono i propri prodotti come “light” o come, nel caso delle barrette di cereali come “sane”. Se questo è effettivamente vero, non può che essere verificato analizzando i valori nutrizionali, una procedura che costituisce una parte importante nel controllo della qualità alimentare. I valori di grassi, acidi grassi saturi, zuccheri e sale stampati sulle confezioni rappresentano una media del contenuto di ogni sostanza e si riferiscono a 100 ml in 100 g di prodotto. Le barrette di cereali sono costituite da un mix eterogeneo di ingredienti (noci, uvetta, fiocchi d’avena, ecc..) pertanto è necessaria una completa omogeneizzazione del campione per ottenere risultati d’analisi significativi.
Cosa rivelano i capelli
Il rilevamento di droghe e farmaci illegali è importante in settori quali la scienza forense, il traffico o competizioni sportive. Sostanze chimiche si possono riscontrare nel sangue, nella saliva, nelle urine e nel capello, quest’ultimo possiede il vantaggio di memorizzare le sostanze per un periodo più o meno lungo, a seconda della sua lunghezza. Oltre al rilevamento delle droghe, i capelli sono utilizzati anche per le analisi del DNA.
Nano particelle con effetti enormi
Gli scienziati hanno studiato le nano particelle (particelle estremamente piccole con meno di 100 nanometri di diametro) per molti anni. A proposito delle nano particelle, sono state sviluppate nuove ed innovative proprietà, es. semiconduttive o superficiali, cosi come l’effetto Lotus che ha aperto possibilità fino ad ora inaspettate.
Esistono diversi metodi per produrre nano particelle. La tecnica “bottom up” coinvolge la sintesi delle particelle da atomi e molecole. Con il metodo “top down”, le particelle vengono ridotte a dimensioni nanometriche tramite la macinazione. Lo strumento adatto per questa applicazione è il mulino planetario a sfere, come i RETSCH PM 100, PM 200, PM 400 che forniscono il necessario input di energia per la macinazione fino a dimensioni nanometriche.
Dalla pianta di cacao alle barrette di cioccolato
Cosa sarebbe il mondo senza cioccolato? La produzione di cioccolato è un processo abbastanza elaborato, di cui un requisito fondamentale è il controllo qualità delle materie prime. La strada dalle piante di cacao alle barrette di cioccolato è lunga. A causa delle molte fasi di lavorazione, raccolta, fermentazione, essiccazione, pulitura, torrefazione, pre-frantumazione e infine la macinazione dei pennini di liquore di cacao da cui vengono estratti cacao in polvere e burro di cacao – ci possono essere differenze significative nella qualità. Il processo di controllo della qualità non comprende soltanto test di pericolosità del prodotto (es. funghi, contaminazione da metalli pesanti) o di altri ingredienti (contenuto di grassi e carboidrati) ma anche la riduzione delle dimensioni per test sensoriali sul liquore di cacao. Questo è importante perché il palato umano percepisce in modo sgradevole particelle più fini di 30 microns.
Perfetta omogeneizzazione con il GRINDOMIX GM 300
La diversità degli alimenti con le spesso differenti proprietà dei prodotti rappresenta una reale competizione per i laboratori di analisi alimentari. Per le attuali analisi, i campioni – che possono essere molto tenaci a seconda della loro durezza o umidità – necessitano di essere ridotti e omogeneizzati in modo sufficientemente fine. I mulini a coltelli GRINDOMIX RETSCH sono lo strumento ideale per venire incontro ai complessi requisiti richiesta dalla preparazione di alimenti. Il
modello GM 200 è ormai consolidato per l’omogeneizzazione di piccoli volumi di campione fino a 700 ml. Per volumi maggiori RETSCH adesso offre il nuovo GRINDOMIX GM 300 con una camera di macinazione del volume di 5000 ml.
Utilizzo del Cryomill per campioni con componenti volatili
Per la riduzione di dimensioni di molti materiali è consigliabile utilizzare un mulino criogenico invece di un mulino che opera a temperature ambiente. Il campione viene infragilito con l'azoto liquido che migliora il suo comportamento di rottura quando viene sottoposto a impatto, pressione e attrito. Inoltre, in questo modo vengono conservati i componenti volatili del campione. Il mulino Cryomill non solo è il mulino criogenico più sicuro e moderno sul mercato ma fornisce anche eccellenti risultati di macinazione.
Mulino a taglienti SM 300 – Affinamento di un sistema di macinazione ben affermato
I mulini a taglienti vengono utilizzati in diverse aree della preparazione dl campione alle analisi successive. Tipiche applicazioni includono la riduzione di combustibili da rifiuto, la macinazione di campioni di biomasse per ricerche nell’ambito delle energie rinnovabili, il controllo dei prodotti nell’abito delle normative RoHS and WEEE, o nel recupero dei materiali preziosi – la varietà di campione è notevole.
Preparazione del campione per la spettrometria in fluorescenza a raggi X
Dal campione in polvere alla pastiglia
Determinazione dei grassi negli alimenti e nei mangimi
Macinazione di campioni a elevato contenuto lipidico
Sample Preparation of Feeds and Forage for NIR Analysis
Near Infrared Spectroscopy is the most important analytical method for the determination of protein content, moisture, fat and ash in feeds and forage. The advantage over classical methods such as Kjeldahl is the simultaneous determination of several parameters. Moreover, NIR spectroscopy is a quick method which requires neither consumables nor reagents. Therefore it is used whenever high sample throughput and great flexibility are required. The identification and qualification of raw materials as well as the quantitative analysis of convenience products can be carried out within seconds to guarantee highest product quality and safety.
A much discussed issue related to NIR analysis is the necessity of sample preparation. Users often face the problem of having to decide whether sample preparation is required or not.
Secondary fuels – Energy for the cement industry
Due to decreasing resources and increasing market prices for primary fuels like oil, gas or coal, it is paramount for the cement industry to search for alternative energy sources. With regard to the CO2 emissions trading, a switch to energy sources which have a neutral CO2 balance can be rather profitable. Usually, these are non-fossil fuels. Industries with high energy consumption have made increasing use of alternative fuels during the last years. Accordingly, the use of so called secondary fuels (also waste derived fuels/wdf or refuse derived fuels/rdf) has gained importance. These are mostly combustible fractions of domestic or industrial waste which cannot be recycled.
Powerful Cutting Mill
The SM 300 excels especially in the tough jobs where other cutting mills fail. It has a freely selectable speed range from 700 to 3,000 rpm with high torque. The mill is convenient to operate and easy to clean. Reliable and extremely efficient sample preparation in the laboratory is now guaranteed with the SM 300.
New Knife Mill Sets Standards
The so-called QuEChERS method (“quick, easy, cheap, effective, rugged and safe”) has been developed to make sample preparation to pesticide analysis more efficient. Serial tests have proved that the analysis results obtained with the QuEChERS method can easily bear comparison with more common methods, such as DFG S19. To guarantee reproducible analysis results, it is essential to completely homogenize the sample. To make sure the sample preparation is reproducible, the homogenization process needs to be carried out with a laboratory mill.
Preparation of Elastic Plastics for the Detection of PAH
Polycyclic aromatic hydrocarbons, short PAH, are usually a by-product of combustion and can be found, for example, in cigarette smoke or oil-based products. Mineral oil containing PAH is often used in rubber products as plasticizer, especially in black-coloured products such as car tyres, rubber grips of tools or rubber shoe soles. It was discovered that some polycyclic aromatic hydrocarbons are carcinogenic, so that maximum permissible values have been determined for the concentration of PAH in consumer products.
Size reduction of elastic plastics with volatile components
Neutral-to-analysis sample preparation for the detection of PAH and phthalates
Renewable raw materials are gaining ground
The representative sample preparation of plants requires experience
Toxic analyses of biological samples
Cryogenic grinding facilitates the preparation of animal samples
Efficient Grinding at –196 °C
RETSCH’s New CryoMill for Safe and Reproducible Grinding with Liquid Nitrogen
Milling of Samples in a Fertilizer Laboratory
The fertilizer laboratory of the Division of Regulatory Services at the University of Kentucky uses the Retsch ZM 200 ultra centrifugal mill for milling fertilizer samples.
Tracking Down Fake Cashmere
Cashmere wool is the best known precious wool. It is won from the cashmere goat which originates from the high mountain region of the same name. Due to its properties such as softness and warmth, cashmere wool gains more and more popularity in the manufacture of clothing. Genuine cashmere is won solely from the goat’s downy hair and must possess a certain hair structure with an exactly defined length and thickness.
Preparation of Soil, Sewage Sludge and Sediment Samples in a Wastewater Treatment Laboratory
The preparation of a mixture of organic and inorganic samples holds some difficulties: whereas sand, clay and stones can usually be ground to homogeneous samples with suitable laboratory mills, the high energy input can cause samples with organic components such as fat or starch to cake. Carsten Bunn, a laboratory technician at the waste water treatment laboratory BRW, has to deal with this problem every day. He treats samples which are taken from the sand traps of the wastewater treatment plants and consist of exactly that mixture. The sediments of household and industry waste water not only contain sand, clay or leaves but anything that people nowadays dispose of through the sewer system: cellulose, hair and especially food residues.
Fast and Reproducible Sample Preparation with a Vibratory Disc Mill
The Vibratory Disc Mill RS 200 from Retsch is used for the quick, loss-free grinding of hard, brittle and fibrous materials to analytical fineness.
Cement - representative sample preparation is important
To produce high-quality cement, the mineralogical and chemical composition of raw materials as well as intermediate and finished products has to be determined. At each stage of the production, samples have to be taken, processed and analysed to ensure quality control without gaps. Retsch offers a range of instruments that are used for sample preparation during the complete production process, from the quarrying of the raw materials to the final product. The typical sample preparation process involves preliminary size reduction, sample division and fine size reduction before the sample can be submitted to further analyses....
Green Chemistry in the Lab
Mechanochemistry is a very effective method to carry out syntheses without solvents and by-products. The technical literature describes a great number of reactions where a conversion of 100% is achieved. A precondition for the establishment of mechanochemistry in the industrial sector is the availability of suitable laboratory mills. A decisive factor is that – similar to conventional preparative chemistry – ambient parameters such as pressure and temperature can be documented and monitored. The Planetary Ball Mills and Mixer Mills from Retsch fulfill these requirements.
Tracking down hazardous substances (RoHS/WEEE)
Preparing electronic waste for obtaining representative analytical samples.
A solution for converting an electrical appliance into a meaningful analytical sample is described using a remote-controlled toy car as an example.
Size reduction within the context of sample preparation
In general “size reduction” is taken to mean the disintegration of solid substances by mechanical forces without altering their state.
Sample Preparation of Electronic Scrap in the Context of RoHS and WEEE
Since August 2004 new EU directives for the disposal of used electrical and electronic appliances as well as the restricted use of certain hazardous substances in these devices have become effective.
Making Whole Cell Extract of Saccharomyces cerevisiae
Preparation at the Courtesy of the Staley Lab at the University of Chicago
Consistent Milling on a Nano Scale
Planetary ball mills are helping scientists and engineers advance nanotechnology by providing a consistent way to produce nanoscale powders.
The preparation of samples of solid substances for spectroscopic analysis
X-ray fluorescence spectrometry is one of the most versatile multi-element methods of chemical analysis. The technique is based on excitation of fluorescent radiation from a sample by bombarding it with high energy X-ray quanta and subsequent study of the characteristic X-ray radiation emitted by its elements.
Bigger is not Better
There is a trend towards smaller samples that have more controlled particle size and yet remain representative of the material being analyzed.
Increasing the development efficiency of ceramic materials
The development of high-performance ceramics is determined by a large number of influencing factors. In addition to material-specific aspects, such as the chemical purity of the initial raw materials, particle size reproducibility and uniformity of particle morphology, production-specific factors also determine the final properties of ceramics.
Sample Preparation of Plastics for X-Ray-Fluorescence Analysis
The elemental analysis of plastics has become more and more important. EC directive 91/338/EWG regulates the ban of cadmium in PVC, EC directive 94/62/EC defines limits for cadmium, lead, chromium and mercury in packing materials and EC directive 2000/53/EC defines limits for the same elements in end-of-life vehicles. This has created a strong need for a rapid and reliable testing method.
Cryogenic Preparation of Sample Materials
Within the context of sample preparation, size reduction plays an important role as it has a substantial influence on the results of the subsequent analysis. If the particles are too coarse or non-homogeneous the results of the analysis may turn out to be incorrect, especially if there is only a very small amount of sample material which represents the total amount.
Cryogenic disruption of yeast cells
The MM 301 can be used for cell disruption applications. In this case, yeast cells were embrittled with liquid nitrogen.
Sample preparation of electronic scrap with SM 2000 and ZM 200
RETSCH mills in the context of RoHS and WEEE
Reliable sample preparation in food technology
An efficient sample preparation procedure for rapid, reliable and reproducible analytical results is becoming increasingly important today. Ever more stringent requirements are being set both in research and production, e.g. for product monitoring and quality control.
Analysis of cadmium in plastics
In recent years, mass media have focused on the topics of the environment and environmental conservation. With the advancement in scientific technology, resource development has progressed.
The Representative Sample Preparation of Waste
Now that a certain environmental awareness has developed in the population over the past few years, our efforts are geared not only to avoiding waste, but also to reducing the mountains of waste which still arise by means of raw material recovery and the reintroduction of secondary raw materials into the industrial cycle.
Vagliatura (8)
Setacciatura di polveri agglomerate con il setacciatore a getto d’aria AS 200 jeting machine AS 200 jet
Il setacciatore a getto d’aria viene utilizzato principalmente per la setacciatura di materiali secchi con particelle di dimensioni inferiori ai 40 micron. Può comunque essere un’alternativa rapida alla classica setacciatura fino a 250 micron.
Separazione di grandi volumi di campione con AS 450 control
L’analisi granulometrica di grandi quantità di materiali sfusi è di solito effettuata tramite vagliatura. Nella maggior parte dei setacci tori disponibili sul mercato la pila dei setacci è collocata su delle molle che oscillano verticalmente. Tuttavia, per distribuire più uniformemente il materiale sull’intera superfiche del setaccio, la così detta setacciatura con effetto 3D utilizzata sull’AS 450 control è il metodo più adatto. Essa è caratterizzata da un movimento circolare sovrapposto a uno verticale e in questo modo il materiale è movimentato su tutto il setaccio.
Air Jet Sieving of Bulk Materials
Particle size analysis and particle size distribution are important criteria for the quality control of bulk materials. In a running production process, the results of a quality check must be available quickly to allow for immediate adjustment of the production parameters. Depending on the expected particle size and sample volume, different sieving methods and sieving machines are suitable for analysis. The method used for particle size analysis is primarily determined by the fineness of the material to be sieved. For dry sieving of samples with particle sizes below 40 microns, air jet sieving is the method of choice.
The Basic Principles of Sieve Analysis
Many natural and manufactured materials occur in a disperse form, which means that they consist of differently shaped and sized particles. The particle size distribution, i.e. the number of particles of different sizes, is responsible for important physical and chemical properties.
Reproducible Sieving in the Shortest Possible Time
Despite the rapid development of modern optical particle measuring techniques, classical sieving analysis is still at the forefront for the practical quality assurance of bulk goods.
Fine Tuning Sieve Analysis for Accurate Particle Size Measurement
All to often, this useful method is overlooked. But if followed, these principles deliver accurate and reliable results at an affordable price.
Put the squeeze on
Sieving is cost effective for particle sizes greater than 75 μ, although the technique can be used for some materials of smaller size if the method can be validated. Assuming the relevant standards and clean, wellmaintained equipment that conforms to the standards are used, sieving can provide an accurate and reproducible measure of particle size distribution within a sample.
Sistemi ausiliari (10)
Representative results require adequate sample preparation
The following situation is typical for many production plants: After a routine quality check, the production process is stopped or an already produced batch is suspended, because the analysis results were not within the relevant critical values. But does the tested product really deviate from the specifications? The quality control managers are convinced of this because modern analysis instruments provide results with very low tolerances. The sample in question was tested several times and the result was confirmed. The question is why the product does not match the specifications although the production parameters have not been changed in any way.
The possibility that the tested product is indeed deficient cannot be excluded. However, it is often not the product itself which causes irregular analysis results but a lack of understanding of the steps which come before the analysis.
Comparative investigations on spinning rifflers
The influence of the degree of mixing of the material and the influence of the operating data of the apparatus were investigated in two spinning rifflers.
Fine Tuning Sieve Analysis for Accurate Particle Size Measurement
All to often, this useful method is overlooked. But if followed, these principles deliver accurate and reliable results at an affordable price.
Put the squeeze on
Sieving is cost effective for particle sizes greater than 75 μ, although the technique can be used for some materials of smaller size if the method can be validated. Assuming the relevant standards and clean, wellmaintained equipment that conforms to the standards are used, sieving can provide an accurate and reproducible measure of particle size distribution within a sample.
Cement - representative sample preparation is important
To produce high-quality cement, the mineralogical and chemical composition of raw materials as well as intermediate and finished products has to be determined. At each stage of the production, samples have to be taken, processed and analysed to ensure quality control without gaps. Retsch offers a range of instruments that are used for sample preparation during the complete production process, from the quarrying of the raw materials to the final product. The typical sample preparation process involves preliminary size reduction, sample division and fine size reduction before the sample can be submitted to further analyses....
The preparation of samples of solid substances for spectroscopic analysis
X-ray fluorescence spectrometry is one of the most versatile multi-element methods of chemical analysis. The technique is based on excitation of fluorescent radiation from a sample by bombarding it with high energy X-ray quanta and subsequent study of the characteristic X-ray radiation emitted by its elements.
Sample Preparation of Plastics for X-Ray-Fluorescence Analysis
The elemental analysis of plastics has become more and more important. EC directive 91/338/EWG regulates the ban of cadmium in PVC, EC directive 94/62/EC defines limits for cadmium, lead, chromium and mercury in packing materials and EC directive 2000/53/EC defines limits for the same elements in end-of-life vehicles. This has created a strong need for a rapid and reliable testing method.
The Representative Sample Preparation of Waste
Now that a certain environmental awareness has developed in the population over the past few years, our efforts are geared not only to avoiding waste, but also to reducing the mountains of waste which still arise by means of raw material recovery and the reintroduction of secondary raw materials into the industrial cycle.
