Nearly all raw materials, as well as products resulting from chemical reactions, are made up of a mixture of substances. To further utilize or process them, these substances are prepared by means of thermal or mechanical separation. While the processes for separating substances have been of vital importance for thousands of years, it might still surprise some to learn just how often they are employed in everyday life.
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.
Separation technologies and their fields of application
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.
- Distillation is often used for the production of high-proof beverages such as whisky and spirits or for the recovery and purification of solvents
- The goal of evaporation is generally the concentration of a substance or mixture of substances for the recovery of valuables substances; as an intermediate step prior to additional processing, or simply to reduce volume and therefore the costs of transport, storage and disposal
- Drying is one of the most common thermal separation processes and is used in the production of polymers, ceramic and metallic powders and nearly all fine chemicals
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.
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.
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).
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.
GEA’s contribution to the development of separation technology
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.
- GEA's separation expertise now encompasses more than 3,500 different processes and 2,500 products for various industries ranging from food & beverage, marine, oil & gas to energy, chemical, pharmaceutical and environmental technology
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.
- Modern GEA evaporation plants are very energy-efficient given the use of smart thermo-technical interconnection and heat pump technology (vapor recompression)
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)
- GEA is one of the world's most experienced companies in the field of drying technology, and beyond spray drying, offers a host of additional dryer types, such as fluid bed and freeze dryers as well as design solutions for diverse starting materials including wet powders, emulsions and solutions
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.
- Even today, the CONRAD™ freeze dryer remains at the heart of most freeze-dried instant coffee factories, where not only first-class products, but also robust operation is guaranteed
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.
- Due to rigorous research and development, GEA offers the finest gas purification technology available to the cement, glass, iron & steel, nonferrous metals, power plants, waste incineration and chemical industries
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.
- Since the building of the first large-scale continuous petrochemical plant in 1990, melt crystallization is primarily utilized in the production of high-purity chemical substances. In the field of food applications, melt crystallization is also referred to as ice concentration. GEA refrigeration plants are at the heart of energy generation.
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.
- This innovative process is also used successfully in solvent recovery and bioethanol production
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.
- The new GEA portfolio offers three different bowls, specifically designed for the processing of insulin, proteins and vaccines. Two self-cleaning design variants and the new GEA flexicon nozzle drum, which can be infinitely adjusted from the outside, enabling operating parameters to be flexibly adjusted, even during production. As a result, pharmaceutical plants are able to produce around 150 different applications with just one machine.