25 Feb 2019
Humans quickly recognized the need to separate substances so that they could use the individual elements directly and immediately, or for further processing. What began as a result of natural processes, was adopted and adapted by humans thanks to their ability to accumulate knowledge and as a result of technological progress over the course of history.
The process of separating mixtures of substances through the application of heat, via mechanical separation or as a result of chemical reaction, was further developed during the course of industrialization and to an industrial scale and has since become an integral part of almost all production processes. Key technical and historical milestones in separation technology include: the sifting of grain, the deliberate evaporation of water and crystallization of salts in lakes and oceans and the filtration of polluted water over charcoal. During the course of industrialization, which was driven by steam generation, thermal processes such as evaporation, drying and distillation were used in separation processes. Knowledge regarding the use of electrical currents led to additional methods, such as the separation of dust via electrostatic precipitators.
Today, separation processes are used to clean raw materials and products, recycle solvents and separate by-products. Within any given industrial production environment, between 40 to 90 percent of the capital and operating costs are dedicated to separation processes and procedures and therefore represent an important cost factor. Luckily, these costs can be reduced through the use of intelligent solutions.
The separation of mixtures from one another is based on the exploitation of the different physical and chemical properties of each particular substance. Often several separation processes must be carried out in succession to obtain the desired end product.
Thermal separation processes exploit diverse material properties such as boiling or freezing point or solubility, and include the following:
Distillation, evaporation and drying, are processes whereby the separation of liquid mixtures within substances takes place due to different vapor pressures or boiling points.
Applications:
Melt crystallization is employed when separation is based on different freezing points.
Applications: Melt crystallization is primarily used for the production of high-purity organic substances in fine chemistry.
Freeze-drying or lyophilization are used when separation is based on the physical process of sublimation, in which the ice crystals directly enter the gaseous state without the occurrence of a liquid phase in between.
Applications: Freeze drying is primarily used for thermally sensitive products or in situations where preservation of shape or aroma is important. A well-known example from the food industry is the freeze-drying of coffee into soluble coffee granules (instant coffee). Another application is the lyophilization of pharmaceutical drugs which, when dissolved in water, do not keep very long.
Crystallization, is when a substance is separated from a solution through the exploitation of the different solution equilibria.
Applications: One of the most common applications of crystallization is for the extraction of salt or the production of fertilizers.
Extraction is employed to separate the mixtures of substances by taking advantage of the diverse solubility characteristics of the pure substances contained within a solvent.
Applications: Treatment of pressing residues resulting from the production of cold-pressed olive oil; the decaffeination of coffee or the extraction of active pharmaceutical ingredients.
Adsorption is used when the physical deposition of a substance on the surface of another solid occurs due to an adsorption equilibrium.
Applications: Removal of pollutants in drinking water treatment using activated carbon or during the production of high-purity alcohol.
Absorption is the process whereby the chemical uptake of a substance occurs in a different phase.
Applications: Purification of exhaust from industrial processes or incineration plants.
Chromatography is used in cases where the physical separation of substances is based on the different distribution of the pure substances between a stationary and a mobile phase.
Applications: Separation of active pharmaceutical ingredients or dyes.
Mechanical separation processes exploit the different particle properties, such as particle size, density, particle inertia, magnetizability or electrical mobility, and include the following:
Sieving is the separation of mixtures that make up substances as a result of different particle sizes.
Applications: Separation of minerals, building materials, fish meal, wood pellets, fertilizers, recycling and household waste.
Filtration, is the separation of mixtures of substances which occurs due to different states of aggregation or different particle sizes.
Applications: Cross-flow membrane filtration processes such as micro-, ultra-, nanofiltration and reverse osmosis for the selective separation of substances, (e.g. biomass- and wastewater treatment and numerous steps in food processing).
Decanting or separating, is the separation of a liquid from a solid that is insoluble due to their different densities.
Applications: Separation of sewage sludge, clarification and classification of different food ingredients or separation of biomass.
Centrifugation is the use of centrifugal force to separate substances that are immiscible due to their different densities.
Applications: Production of dairy products, beer, wine, juices, fine chemicals and in cleaning edible oils and mineral oils.
Magnetic sheaths are used when separating substances with different magnetic properties.
Applications: Separation of iron and steel scrap during waste processing or elimination of metals from a dust mixture to protect downstream equipment.
As a process specialist, GEA has for decades, provided technologies covering nearly every separation process for the chemical, pharmaceutical as well as the food and beverage industries – each tailored to the requirements of our diverse customers. Our processes and product developments have contributed to important milestones within key industries.
In 1893, the merchant Franz Ramesohl and cabinetmaker Franz Schmidt opened a workshop in Oelde, in northwestern Germany, to manufacture hand-operated centrifuges – patented as a milk centrifuge. GEA’s operations at this site continue to draw on these early company roots, and is today one of the most modern separation plants in the world.
In the field of thermal separation technology, the first falling film evaporator was patented by Paul Kestner in 1899 and widely used throughout Europe. The multi-stage circulating evaporator, patented by Wilhelm Wiegand in 1908, was another milestone in the development of evaporation technology. Thermal processes are very energy-intensive and reusing energy is still the goal today.
The foundation for modern spray drying was established in 1924 with the invention of the rotary atomizer by Johan Ernst Nyrop. Today, spray drying has become indispensable in industrial food processing, as well as in numerous applications within the chemical and pharmaceutical industries (e.g. production of hard metals; electrode material for lithium batteries; ceramic materials and plastics)
With the development of the freeze-drying plant CONRAD™ in 1968, GEA enabled the continuous processing of products such as coffee and tea, fruits, vegetables, meats and seafood as well as ready-to-serve meals in large quantities.
Reducing emissions is a key goal in protecting our environment globally and GEA was and is a frontrunner in developing state-of-the-art gas purification technologies for the reduction of pollutants in industrial exhaust gases. We supplied one of the oldest large-scale electrostatic precipitators in the metal industry already in 1912 and continued to conduct research on dust separation which led to the development of the adjustable annular gap scrubber in 1982.
In 1990 GEA was granted a patent for a multi-stage countercurrent melt crystallization system, a process for the purification and separation of organic chemical mixtures and aqueous beverages such as juices, beer, tea and coffee. The process, which is suitable for continuous operation, has decisive advantages due to the relatively low energy requirement of the freezing process and the high selectivity of the crystallization.
With its innovative design for a whisky distillation plant, GEA succeeded in reducing energy consumption by 40 percent. The plant concept, for which a patent application was filed in 2007, is based on the reuse of energy in the process supported by mechanical vapor recompression.
The Pharma Separator series developed in 2018 offers manufacturers maximum flexibility for nearly all pharmaceutical applications. GEA flexChange separators consist of a drive and three interchangeable drums enabling quick reaction to process and market changes.