摘要:
A process is described for recovering alkali-chloride and alkali-sulfate salts from a salt solution. The salt solution comprises alkali metal, chloride and sulfate ions and is directed to a hydrous salt crystallization unit (28) which crystallizes hydrated sulfate salts that comprise sulfate and at least one alkali metal. A purged solution from the hydrous salt crystallization unit (28) is directed to a chloride salt crystallization unit (38) while the hydrated sulfate salt crystals are melted to form an aqueous sulfate solution which is directed to a sulfate crystallization unit (32). Anhydrous sulfate salts are crystallized from the aqueous sulfate solution to form sulfate salt crystals comprising sulfate and at least one alkali metal. In the chloride salt crystallization unit (38), chloride salt is crystallized to form chloride salt crystals. At least a portion of the purges from the sulfate and chloride salt crystallization units (32, 38) is directed to the hydrous salt crystallization unit (28).
摘要:
The present invention provides a continuous process for producing ammonium sulfate crystals, wherein said process comprises: (a) feeding to a first group of crystallization sections, which crystallization sections are heat integrated in series, a first aqueous ammonium sulfate solution that contains one or more impurities; (b) feeding to a second group of crystallization sections, which crystallization sections are heat integrated in series, a second aqueous ammonium sulfate solution that contains one or more impurities; (c) crystallizing ammonium sulfate crystals in each crystallization section respectively from each of said solutions of ammonium sulfate that contain one or more impurities; (d) purging a fraction of the ammonium sulfate solution that contains one or more impurities from each of said crystallization sections; and (e) discharging ammonium sulfate crystals from each crystallization section, characterized in that: (i) both the first group of crystallization sections and the second group of crystallization sections are together heat integrated in one series of crystallization sections; wherein the first group of crystallization sections operates at higher temperature than the second group of crystallization sections; and (ii) the composition of the first aqueous ammonium sulfate solution that contains one or more impurities is different to the composition of the second aqueous ammonium sulfate solution that contains one or more impurities. Further provided is apparatus suitable for producing ammonium sulfate crystal.
摘要:
Appareil de cristallisation du soluté contenu dans une solution, comprenant : une première (2) et une deuxième (1) chambres communicantes, pour ladite solution, et des moyens (20) pour y maintenir un état de sursaturation, - un premier circuit pour extraire d'une zone calme (15) de la dernière chambre, un premier courant de liquide à petits cristaux et pour recycler ce courant dans la première chambre, et un deuxième circuit pour extraire de la deuxième chambre, un deuxième courant de liquide à gros cristaux, et pour amener ce deuxième courant dans la première chambre, l'extrémité avale (26) du premier circuit débouchant dans le deuxième circuit de manière à ce que les premier et deuxième courants de liquide soient amenés à s'écouler dans le même sens dans ledit deuxième circuit.
摘要:
The process of the invention deals with significant improvements in salt purity and whiteness brought about through treatment of brine with alum prior to charging into crystallizers for solar salt production. The improvements realized are partly on account of elimination of suspended impurities like gypsum and clayey matter in the brine, which may otherwise be carried along with the brine in the crystallizer and finally end up in the salt, and partly due to the improved crystal size and morphology that minimizes embedded impurities in the salt. Rain washing of the heaped salt has resulted in a salt with greatly reduced calcium and sulphate impurity levels hitherto not achieved in solar salt production. Alum treatment by the process of the invention requires no additional time or infrastructure and the cost of the treatment works out to
摘要:
Disclosed is an optimized process and apparatus for more efficiently producing and purifying aromatic dicarboxylic acids (e.g., terephthalic acid). The optimized system employs at least one zoned slurry concentrator to enhance purification of the aromatic dicarboxylic acid.
摘要:
A crystallization apparatus having an agitating vessel, a liquid circulating means which circulates a liquid or slurry along the wall of the agitating vessel and one or more means for generating a temperature difference which can generate a temperature difference on the wall of the vessel. The temperature difference generating means is disposed, for example, in or below a region at which a liquid or slurry being sprayed from a liquid spraying device by the rotation of the device contacts with the wall of the vessel and renders the temperature of the liquid or slurry sprayed to be higher or lower than that of a liquid or slurry surrounding it. The crystallization apparatus provides large areas for evaporation and heat transfer, which leads to a decreased induction period for crystal formation, and thus results in the formation of crystals having a large average particle size and a narrow particle size distribution. Further, the apparatus can be used for obtaining substantially only crystals of a specific crystal form, that is, the apparatus enables the control of crystal polymorphism.