Industrial crystallization, hardness salts

The ultra-micro-hardness of inorganic and organic salts has been measured for 15 substances. These are products usually produced in industrial crystallization. The hardness-force-dependency was examined and data are compared to those from literature. In the case of potassium nitrate a strong direction dependency of the hardness was observed. Also effects of impurities in the crystal lattice were analysed. In the end an attempt has been introduced to calculate the hardness of crystals from a physical model. 

ULRICH KRUSE Hardness of Salts Used in Industrial Crystallization... 

As a final example of the use of pressure agglomeration for minerals, various applications of roller presses in the salt (sodium chloride) industry shall be discussed. The technology is used for the size enlargement of rock salt fines and of crystallized byproduct salt from the concentration of potassium chloride and for potassium chloride itself and for other salts. All salts deform easily under pressure and, while becoming corrosive in the presence of water, do not cause much mechanical wear unless hard solid impurities or contaminants are present, which happens rather infrequently. 

Phosphonates are surface-active chelants and are widely used in industry for scale and corrosion control, and in cleaning agents, dispersants, and other applications. The annual sales of phosphonates in the U S A amount to over two billion dollars per year [8]. Phosphonates inhibit calcium scale formation by interfering with the crystal structure of calcium salts, making the crystals softer so that they are more easily removed by washing - the threshold effect [9]. A key application is controlling scale particularly in hard-to-reach places such as laundry and dishwashing machines. 

The rosanilins are powerful triacid bases, are colorless, but combine with acids to form brilliantly colored salts. Fuchsine is industrially obtained from anilin oil, which contains both anilin and toluidin, neither of which in the pure state will produce a red color. The process consists essentially in heating the-oU with a mixture of nitro-benzene, hydrochloric acid and iron filings. The product is a mixture of the chlorids of rosanilin and pararosanilin, is in hard, green crystals, soluble in water and alcohol, to which it communicates a brilliant red color. 

A major reason for the popularity of pharmaceutical co-crystals in industry is that they lend themselves well to patent protection. They admirably satisfy the three criteria of patentability, namely novelty, non-obviousness and utility. A co-crystal almost always satisfies the novelty criterion because it is a new composition of matter. Non-obviousness is provided by the fact that the identification of the co-former is hardly ever routine, unlike say salt formation wherein an acid is obviously required to make a salt from a base. Utility is generally the only criterion that must be established but it is often easy to demonstrate—usually it is the lack of a particular attribute (solubility, bioavailability, dissolution profile, good shelf life) that has led to the identification of a pharmaceutical co-crystal. With respect to patentability, co-erystals offer opportunities vis-d-vis polymorphs. They are clearly new substances, problems of inherent anticipation are not likely to arise so often and more of them can be made for any given API, expanding the pharmaceutical space around it and consequently the types of advantageous properties that may be accessed. 

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