Sample Preparation in the Laboratory FRITSCH GMBH Milling & Sizing Dagmar Klein Sales Manager Industriestr. 8 55743 Idar-Oberstein FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Agenda Presentation of the company Sampling & sample division Premium line a new reference class Sample preparation Task Physics of comminution Comminution instruments FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Application-oriented laboratory instruments from the world market leader FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Your partner with over 85 years of experience FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
SAMPLE PREPARATION AND PARTICLE SIZING – Products and brand name – Instruments from FRITSCH are known around the world under the brand names PULVERISETTE ANALYSETTE LABORETTE Instruments for comminution Instruments for particle sizing Instruments for dividing and feeding FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Sampling and sample division The full initial quantity of a substance to be analysed, for instance to determine its chemical composition, is generally significantly larger than the quantity that can be analysed. This makes sampling, sample division and preparation of the sample necessary. The result of an analytical process can only supply meaningful information if the analysed sample is representative of the material investigated. Initial quantity → desired → Q(x) ↓ Sampling (laboratory sample) ↑ ? ↓ Sample division → analysis → Q*(x) Systematic, random and statistical errors can lead to deviations between Q(x) and Q*(x). FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Errors in sample preparation Contamination Material loss (recovery) and demixing Changes to the compositions (decay) & and the matrix through thermal and physical forces Active ingredient analysis in the pharmaceutical industry Quality parameters of polymers (colour, moisture, cluster destruction) SiC preparation (decay) Samples – surface e.g. X-ray analysis (mineralogical effect - particle size effect) Rheology of polymer powders such as pourability FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Theoretical aspects of sample preparation The core problem of sampling and sample preparation is the inhomogeneity of the samples Extremely pronounced in solid materials, but flowing gases and liquids are also inhomogeneous. Additional inhomogeneity is possible over time (e.g. demixing during sample preparation) The max. achievable homogeneity during sample preparation is uniform, random mixing - true mixed state !!!!!! FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Factors influencing inhomogeneity and demixing Inhomogeneity in solids due to physical parameters, such as: Generally applicable !!!!! Particle size distributions Particle shape The more inhomogeneous a sample, Density the larger the sample quantities Attractive forces that must be prepared through: Inhomogeneity in fluids caused by: 1. Grinding Density 2. Wet chemical dissolving processes Recrystalisation 3. Break-up (e.g. microwave) Fluid bridges Attractive forces (Van der Waal's force, etc.) FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Conditions for the sampling and preparation Sampling Site, location, position of the sampling Size, quantity, volume, number of samples Time, duration, frequency of the sampling Homogeneity of the sample Contamination of the sample Requirements on sample storage and transport FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Additional perspectives on sample preparation Protection against toxicity Ignitability, flammability, burning behaviour and caloric value Reaction with air and humidity Gas formation, outgassing, vapours Heavy metal contents FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Sample division possibilities Systematic errors A risk of demixing exists during sampling, sample division and preparation Remedy during sampling: Multiple partial quantities are removed at statistically distributed points and mixed . Remedy during sample division: 1. Coning and quartering 2. Sample splitters: halves the sample 3. Rotary sample splitter: 1:8; 1:10; 1 :30 FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Rotary Cone Sample Divider „laborette 27“ � Representative division of dry solids or suspensions � Dividing heads with ratios 1:8, 1:10 and 1:30 � Representative division of randomly segregated samples FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Main Advantage of Rotary Cone Sample Divider � Rotation of Cone: � spreading sample over 360° � splitting sample into very small volume elements � feeding sample simultaneously to the sample containers FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Sample division and its importance With sample division Rotary cone sample divider Without sample division Representative division Ratios 1:8, 1:10 and 1:30 FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Fineness - Definition Definition 1 Particle size Crushing > 5 mm Grinding < 5 mm Fine grinding < 100 µm Micro-fine grinding < 10 µm Ultra-fine grinding < 1 µm Definition 2 Analytical fineness: < 63 µm FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Sample comminution Coarse from 100-300 mm to 0-30/50 mm For hard minerals: Cone, jaw or single impeller crusher For medium-hard and soft minerals: Roller, impact and hammer crushers Medium from 30-50 mm to 5-8 mm For hard minerals: Fine cone, jaw and single impeller crusher For medium-hard and soft minerals: Roller mills and fine impact or hammer crushers Fine from 5-8 mm to 1 mm and smaller For minerals with various hardness levels: Vibrating mills, ball mills, rod mills FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Criteria for selection of a laboratory mill 1 Material Physical and chemical properties Starting parameters Quantity Particle size Representative quantity? End parameters Particle size Size range FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Criteria for selection of a laboratory mill 2 Abrasion What abrasion must be avoided What abrasion is allowed Number of samples Grinding time FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Criteria for selection of a laboratory mill 3 Additional usage options Wet grinding possible? Cryogenic grinding required? E.g. plastics Grinding under inert gas required? Cleaning Sample carry-over Duration FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Criteria for selection of a laboratory mill 4 Costs Instrument costs Accessories Personnel costs Operating costs FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Material properties / Mohs hardness Mohs Material hard- ness Soft Talcum, graphite, kaolin 1 1.5 Soda, clay, diatom earth 2 Gypsum, bitumen, kaolin, sulphur, rock salt, bicarbonate Silver 2.5 3 Calcite, anthracite 3.5 Dolomite, copper ore 4 Fluorite, zinc blende 4.5 Siderite, magnesite Medium-hard Apatite 5 5.5 6 Feldspar, iron Pyrite, iron ore 6.5 Quartz 7 8 Topaz Hard 9 Corundum 9.5 Silicon carbide Diamond 10 FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Important term definitions Ductility (Latin from ducere (to pull, lead, guide)) The property of a material to deform plastically under overloading before breaking e.g. precious metals (gold,platin) Toughness, tenacity Describes the resistance of a material against the spreading of tears or breaking. This takes place through energy absorption via plastic deformation. e.g. most ferroy alloys (ferro manganese, ferro vanadium etc.) Brittleness The opposite of toughness. Examples of brittle materials are glass, ceramics and some plastics. These materials have only limited ability to plastically deform and can therefore absorb significantly less energy than tough materials before they break. e.g. minerals (quartz, basalt) or coal, inorganic salts, feed pellets, Fracture toughness or tear toughness!!!!!!! A term from fracture mechanics that describes the resistance of a material to FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009 developing tear growth
Material properties – Facture toughness at room temperature – Steels GFRP Al alloys Al 2 O 3 Wood SiC Pb, Ag, Cu Polyethylene PMMA Reinforced Window glass Polyester concrete Concrete Epoxy Ceramics Metals Polymers Composite materials FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
Material properties – Effects and selection for the comminution principle – FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
What principle is appropriate for comminution? – What to which? – FRITSCH GMBH • Milling and Sizing • Idar-Oberstein • Germany � 2009
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