Phosphoric acid for removing calcium and magnesium
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I read in the Chlor-Alkali magazine that phosphoric acid can be used to remove calcium and magnesium, and it can basically help achieve the quality standards for secondary brine. Excessive amounts of phosphoric acid have an adverse effect on the membranes, and magnesium phosphate has a high viscosity, making it difficult to remove from the membrane tubes. Please have a colleague from Chuanyou who uses the calcium and magnesium removal process with phosphoric acid share information on the following aspects: the impact on the electrolytic cell, the impact on membrane filters, the impact on filter presses, what is the appropriate amount of excess phosphoric acid, and daily operation controls.
We don’t need this; just hold it up
Phosphate has a significant impact on the membrane; in practice, it is common to add phosphate after sodium carbonate has been added and the reaction has completed. Excess phosphoric acid circulates within the system, and it reacts with elements such as calcium and magnesium even before any purification is carried out. The resulting calcium magnesium phosphate is sticky and deposits on the membrane tubes, which not only affects flow rates but also makes it difficult to remove. Have those who have used this system encountered such a problem? How can it be solved?
Few manufacturers use it these days; at most a few do.