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In chemical engineering crystallization occurs in a crystallizer. Crystallization is a unit operation through which a chemical compound, dissolved in a given solvent, precipitates under certain conditions to allow successive separation between the phases.
Crystallization is therefore an aspect of precipitation, obtained through a variation of the solubility conditions of the solute in the solvent, as compared to precipitation due to chemical reaction. |
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Crystallization is one of the pristine unit processes. It may be assumed that our ancestors used sodium chloride found in crevices of the surface rocks after drying caused by solar radiation: this process is still in use in modern solar ponds.
Other crystallization processes, for exampuction, followed by sodium chloride), or in pigment manufacturing, were used in ancient times. These substances were sometimes produced by crystallizing the solutes of some more or less natural brine.
In more recent times, the fast expansion of the chemical industry has required a thorough study of the dynamics of crystallization, and this unit operation is now used in many industrial manufacturing areas: table salt, sugar, sodium sulfate, urea, just to name a few, are produced by crystallization from solutions.
Crystallizer technology has progressed alongside with the new processes. Once simple tanks in which, through cooling, evaporation or maybe through pH variation a crystal was obtained, nowadays continuous machines ensure a remarkable consistency in the product characteristics. Among the first models of modern crystallizers were probably the calandria type, being today the standard crystallizer for sucrose, and the Oslo, named after the Norwegian capital, since it was developed to produce salt in a climate not particularly fit for solar ponds, salt being widely used in Norway in stockfish production. The Oslo type was probably the first crystallizer designed specifically for the control of crystal growth. |
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Reclaim wastewater and recover valuable products
Crystallizer systems from Shail Vac can help you reduce your wastewater discharges and, in many cases, capture revenue-producing products. The technology reduces your environmental impact and help you achieve zero liquid discharge.
A typical system uses other technologies, such as an Brine Concentrator, evaporator, or reverse osmosis system, to preconcentrate the wastewater. The cystallizer then converts the remaining waste to two products:
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Water clean enough for reuse in the plant |
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Solids that are easy to and suitable for landfill disposal |
Crystallizers can recover specific salts that can be sold to offset operating costs. Because industrial wastewaters often contain mixtures of salts in variable concentrations, the design of an effective crystallizer system requires special expertise. We can custom design your system, drawing on a large database of mixed-salt crystallizer installations and decades of operating experience. That means you get a cost-effective and reliable solution.
The crystallizers are simple to install, generally skid-mounted and fully packaged with all auxiliary equipment and controls. Automated controls and wash systems make the equipment easy to operate. Systems use mechanical vapor recompression (MVR) technology to recycle the steam vapor, minimizing energy consumption and costs.
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