Para el análisis de muestras sólidas existe una gran variedad de métodos entre los que pueden mencionarse la AAS, ICP, NIR y FRX. Todos estos métodos tienen algo en común, y es que la muestra a analizar deber ser homogeneizada y tener una granulometría determinada que variará en función del método analítico empleado. La homogeneización y reducción de la muestra a la granulometría indicada se realiza normalmente con trituradoras y molinos de laboratorio adecuados para cada caso.
El agotamiento de los recursos y el aumento del precio de los combustibles primarios tales como el petróleo, el gas o el carbón han obligado a la industria del cemento a buscar fuentes alternativas de energía. Otro factor contribuyente es, sin duda, el comercio de emisiones que hace todavía más rentable el cambio a fuentes de energía con un balance neutro de CO2, en su mayoría combustibles no fósiles. En los últimos años, se ha registrado un incremento en el uso de fuentes de energía alternativas, especialmente por aquellas industrias con una alta demanda energética. En consecuencia, viene ganando cada vez más importancia el empleo de combustibles secundarios o alternativos, que en su mayoría son extraídos de residuos urbanos e industriales – es decir, residuos urbanos que no han podido ser recuperados ni reciclados.
Por lo general se asocia a la noción "fragmentación", el machacamiento, de sustancias sólidas mediante fuerza mecánica. Pero también la división de líquidos en gotas o de gases en bollas representa un proceso de fragmentación.
Plastic is an inherent part of our everyday lives; it is used in a huge variety of things such as, for example, packaging, furniture, clothing or electronic devices. Though the utility of the material is undoubted, consumers are increasingly unsettled by recurring news about hazardous substances detected in plastics. Substances such as plasticizers, which are not firmly bound in the material, are absorbed via the skin and can influence the hormonal balance. Plasticizers contained in food packaging, for example, penetrate into the food and thus into the human body when the food is eaten. Plasticizers in toys are a particularly serious problem; children tend to take toys into their mouths thus absorbing the dangerous chemicals. Equally hazardous are polycyclic aromatic hydrocarbons (PAH). The family of PAH comprises more than 100 compounds most of which have been found to be carcinogenic.
Outdoor activities such as hiking, biking or climbing are very popular. As a result, the textile industry offers a huge variety of functional outdoor clothing made from synthetic high-tech materials which are wind- and waterproof as well as breathable. In 2013 Greenpeace published a study proving that hazardous substances such as perfluorinated and polyfluorinated chemicals (PFC) were used in weatherproof clothing as protection against water or dirt.
This article describes the sample preparation process with cutting mills and cryogenic mills of high-tech fibres.
Reliable and accurate analysis results can only be guaranteed by reproducible sample preparation. This consists of transforming a laboratory sample into a representative part sample with homogeneous analytical fineness. Retsch offers a comprehensive range of the most modern mills and crushers for coarse, fine and ultra-fine size reduction of almost any material. The product range also comprises a wide choice of grinding tools and accessories which helps to ensure contamination-free preparation of a great variety of sample materials. The selection of the correct grinding tool depends on the sample material and the subsequent method of analysis. Different grinding tools have different characteristics, such as required energy input, hardness or wear-resistance.
Sample preparation of vegetable-based raw materials with laboratory mills
Thanks to the increasing usage of biomass as a source of energy, the analysis of these materials in the context of R&D and quality control gains importance, too. Due to the complex properties of plant materials, adequate sample preparation can be rather a challenge.
Use of laboratory grinders for size reduction of human bones and bioceramics
Bone implants and substances for bone regeneration are used in surgery to replace degenerated bone material by implants or to “re-build” it with specific substances. The material used in implants varies from autogeneic (supplied by the patient) through allogeneic (supplied by a donor) bones to replacement materials such as hydroxylapatite (HA) and tricalcium phosphate (TCP). Bovine bones and corals are used in conjunction with synthetically produced foamed materials to form a basis for the regeneration of bone substance. Various RETSCH mills are suitable for the preliminary and fine grinding of human bones as well as bioceramic materials.
A faultless and comparable analysis is closely linked to an accurate sample handling. Only a sample representative of the initial material can provide meaningful analysis results. Rotating dividers and rotary tube dividers are an important means to ensure the representativeness of a sample and thus the reproducibility of the analysis. Correct sample handling consequently minimizes the probability of a production stop due to incorrect analysis results. Thus correct sample handling is the key to effective quality control.
Quality control is an important aspect of cement production. Sample preparation is an essential part of it, because only a representative and reproducible processing of the sample material ensures reliable and meaningful analysis results. RETSCH offers a range of instruments for dividing, crushing, grinding and sizing all materials which are involved in the production process of cement, including secondary fuels. To ensure the right choice of instrument for the right sample material, Retsch offers free-of-charge sample testing in application laboratories all over the world. Elemental analysers based on combustion technology are a useful addition to XRF analysis for the quality control of cement and related products, ensuring fast, precise and reliable determination of carbon and sulphur. With its offering of analyzers using resistance or induction furnaces or both, ELTRA covers a wide range of applications for C and S determination in organic and inorganic samples. The product range is ideally suited to the variety of analytical applications in a cement plant.
The EU directive 2000/53/EG stipulates that as of 2015 95 % of the weight of a car that has reached the end of its life span have to be recycled. The work of ARN is strongly focused on this objective. Together with partner companies they make sure that old cars are processed in an environmentally compliant way. The recycling chain begins with the companies that dismantle the car and remove raw materials and liquids. Waste management companies collect these materials and deliver them to the processing companies who reuse the materials in accordance with high production standards.
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.
Wood residues from forestry work and wood processing are usually processed to wood chips. These can be used in different ways, depending on the type of wood, bark and residual moisture, for example as raw material for chipboards or as substrate for the cultivation of mushrooms. The major part, however, is used for energy generation. The quality of the wood chips can vary significantly, depending on their origin and condition. Trade and industry are interested in the percentage of dry matter and in the calorific value of the chips as the price calculation depends on the water contents of the product. With the analysis result representing an important economic factor, the representative and reproducible sample preparation gains importance, too.
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.
Cutting mills are used in many different areas of sample preparation for subsequent analyses. Typical applications include the size reduction of secondary fuels, the processing of biomass for renewable energy research, the control of products in the context of RoHS and WEEE regulations or the recovery of precious metals – the variety of sample materials is huge.
X-Ray fluorescence is one of the most versatile methods to determine elements in a sample. The material is exposed to x-rays that cause each element to emit its own unique fluorescent x-ray. The subsequent analysis of the results is based on comparisons to standard samples with given chemical composition.