Abstract: Method for the production of a coarse-grained ammonium sulphate product by crystallization and installation for carrying out the method from an ammonium sulphate solution in a DTB type crystallizer having an internal suspension circuit and a clarifying zone, from which a clarified partial flow of solution is constantly drawn off into an external circuit, is heated in a heat exchanger to dissolve the solids contained therein and is guided back as a clear solution into the lower region of the crystallizer. A fine crystal suspension flow is drawn off from the clarifying zone as a further partial flow and guided back into the internal circuit of the crystallization stage without any previous dissolution of the solid proportion contained therein.

Abstract: Method for the production of a coarse-grained ammonium sulphate product by crystallization and installation for carrying out the method. A method for the continuous production of a coarse-grained ammonium sulphate product from an ammonium sulphate solution in a crystallizer operates in accordance with the DTB principle and has an internal suspension circuit and a clarifying zone, from which a clarified partial flow of solution is constantly drawn off into an external circuit, is heated in a heat exchanger so as to dissolve the solids contained therein and is then guided back as a clear solution into the lower region of the crystallizer. In order to ensure production of a product crystallizate with a grain coarseness which is practically constant over time, a fine crystal suspension flow may be drawn off from the clarifying zone as a further partial flow and guided back into the internal circuit of the crystallization stage without any previous dissolution of the solid proportion contained therein.

Abstract: The invention proposes a method and a device for continuously producing a crystallite, wherein a metered amount of seed crystals is fed continuously to the internal solution circuit of a crystallizer, in particular a DTB crystallizer, through a crystallization seed line from a seed generator preferably designed as a flash crystallizer. The amount of seed crystals fed is controlled by an electronic control system as a function of a measured value determined by a sensor, said value being representative of the particle size distribution of the crystallites in the solution in the internal circuit in the crystallizer. By way of a line, the seed generator receives a partial stream of the external solution circuit of the crystallizer, said external circuit being routed through a line. Excess fine crystalline suspension can be fed back to the external circuit from the seed generator by way of a return line.

Abstract: A method and installation for the production of a coarse-grained ammonium sulfate product by crystallization includes firstly generating a crystal having a grain smaller than the desired grain size in a pre-crystallizer and withdrawing a suspension therefrom, from which the fine crystal was previously separated in a classification connecting piece. This suspension, which contains medium-sized grain, is then conducted with a proportion of undersaturated mother liquor, which is sufficient for further crystal growth, into a DTB product crystallizer and crystallized therein to a desired grain size. The heating of the product crystallizer is performed by the heat contained in the vapors of the pre-crystallization. The pre-crystallization may also operate according to the DTB principle, wherein the mother liquor needed for crystallization is supplied in the form of separately admixed concentrated sulfuric acid and ammonia into the external solution loop of the pre-crystallizer.

Abstract: The invention proposes a method and a device for continuously producing a crystallite, wherein a metered amount of seed crystals is fed continuously to the internal solution circuit of a crystallizer, in particular a DTB crystallizer, through a crystallization seed line from a seed generator preferably designed as a flash crystallizer. The amount of seed crystals fed is controlled by an electronic control system as a function of a measured value determined by a sensor, said value being representative of the particle size distribution of the crystallites in the solution in the internal circuit in the crystallizer. By way of a line, the seed generator receives a partial stream of the external solution circuit of the crystallizer, said external circuit being routed through a line. Excess fine crystalline suspension can be fed back to the external circuit from the seed generator by way of a return line.

Abstract: A method and installation for the production of a coarse-grained ammonium sulfate product by crystallization includes firstly generating a crystal having a grain smaller than the desired grain size in a pre-crystallizer and withdrawing a suspension therefrom, from which the fine crystal was previously separated in a classification connecting piece. This suspension, which contains medium-sized grain, is then conducted with a proportion of undersaturated mother liquor, which is sufficient for further crystal growth, into a DTB product crystallizer and crystallized therein to a desired grain size. The heating of the product crystallizer is performed by the heat contained in the vapors of the pre-crystallization. The pre-crystallization may also operate according to the DTB principle, wherein the mother liquor needed for crystallization is supplied in the form of separately admixed concentrated sulfuric acid and ammonia into the external solution loop of the pre-crystallizer.

Abstract: A method and apparatus are provided for depleting sodium thiocyanate (NaSCN) from washing solutions to obtain pure sodium thiocyanate. By adding an anti-solvent such as ethanol, which acts as anti-solvent for the main part of the accompanying salts in the solution, the major part of these accompanying salts can be separated by precipitation in a crystallization and removed, for example, by filtration, whereas the NaSCN remains in the solution. After separating the anti-solvent from the remaining aqueous solution in a rectification, a very pure crystallized NaSCN is produced in a NaSCN crystallization. After washing in a counterstream washing apparatus, the obtained crystallized NaSCN product has a purity of at least 99%.