Is a mixture separated

EL-MO elements and molecules, textbook

Raw materials - processing 62 62 2.15 Separation and enrichment The raw materials are mostly mixtures. If you want to extract a certain substance from a mixture, you have to isolate it from the raw material mixture. For this purpose, the undesired components (usually referred to as impurities) are separated off as far as necessary. There are no 100% pure fabrics. Sometimes it also makes sense to separate raw materials that consist of many components into groups (fractions) of substances with similar properties (e.g. distillation of petroleum). Enrichment is called separation processes in which the proportion of the desired component is increased. For example, when separating metal ore from waste rock, the proportion of ore in the mixture is increased from 40 to 75%, for example. The choice of the separation method depends on the amount of substances to be separated, the number of components in a mixture, the states of aggregation (phases) of the individual components and on whether the mixture is homogeneous or heterogeneous. Well-known separation processes are filtration, distillation, extraction, chromatography and flotation. Filtration This is the separation of certain heterogeneous mixtures. Solids in particular are separated from a liquid or a gas. The technique with funnel and filter paper is only suitable for small quantities in the laboratory. In the industrial sector, candle filters and drum filters are mostly used for liquid mixtures, while cyclones, bag filters and electrostatic filters are used for gas / solid mixtures. Distillation The main purpose of this process is to separate liquid mixtures. The mixture is heated in a vessel, the components with the lower boiling points evaporate more easily and are then condensed. Most of the components with the higher boiling points remain in the vessel. The technique shown in Fig. 196–2 is only used in the schnapps distillery and for small quantities in the laboratory. In most industrial processes, internals are used between the flask and the cooler, which provide better separation. Such distillations are referred to as column distillation. Extraction This method is used to separate certain components from a solid or liquid mixture. The mixture to be separated is treated with a solvent and this dissolves the desired components from the mixture. The solution is separated off and the solvent may then be evaporated (e.g. extraction of edible oil from oil fruits). Flotation With the help of flotation, solid mixtures are separated based on the different wettability and density of the individual components. The mixture to be separated is crushed and mixed with plenty of water and additives (wetting agents, foaming agents). The additives are chosen so that one component is wetted by the solution, but the other is not. If a solid particle is not wetted by a liquid, it tries to "get out" of the liquid. Foam bubbles, in which it accumulates, are used for this purpose. The non-wetted particles of the mixture therefore collect in the foam, which is generated by stirring and blowing in air. They flow out of the vessel with the foam. The wetted particles, on the other hand, sink to the bottom in the separation vessel. An important application of flotation is, for example, the separation of a metal ore from the dead rock (Fig. 62–3). Fig. 062–2: Natural substances - new substances Fig. 062–3: Flotation “pure substances” fractions Mixtures Mixtures whose components have similar properties Mixtures with a higher proportion of the desired component RAW MATERIAL = Mixture Mixture separation enrichment Fig. 062–1: Batch separation NEW SUBSTANCES Naturally occurring substance Synthetic substance Occurring in nature Not occurring in nature RAW MATERIAL = Mixture Separation of the desired substance Chemical reaction (s) End product Natural substance ore - mixed with deaf rock water Foamer Wetting agent enriched ore Deaf rock Air Stirring For testing purposes only - property of the publisher öbv

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