Problems in Calciners

Logic dictates that when corrosion occurs in a calciner, one should lower the temperature to determine if a satisfactory product can be obtained. This was done and corrosion became much worse. It was soon learned that the bed was much less corrosive to steel at higher temperatures where melt crystallized to crystals more quickly. When optimum temperatures and feed rates were determined, high-quality crystals could be made without causing harm to the calciner. This process was scaled up to pilot plant size and will be discussed in more detail in Chapter 7. 

Along the way we have mentioned other long-chain sodium polyphosphates. In science there is one known as Maddiell s salt. In industry this salt is called IMP, which stands for insoluble sodium metaphosphate. Like so many salts in industry it is a complete misnomer. It is not insoluble. It is a polyphosphate with a metaphosphate composition, just as the other phosphate fibers are polyphosphates with metaphosphate compositions. It is sodium and it is an extremely interesting substance, because it is completely harmless and is ever so slowly soluble. 

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