Some companies mistakenly believe that the use of magnesium chloride anhydrous can overcome the halogen-returning and frosting phenomenon of magnesium oxychloride materials. If you can’t grasp the correct quantitative reaction molar ratio between magnesium oxide and magnesium chloride in the material composition, you can’t use the admixtures and the correct process system rationally and effectively. Even if the magnesium chloride anhydrous is used, the phenomenon of back-halogenation and frosting will also occur. .
Since this type of magnesium chloride anhydrous is an industrial by-product, the content of magnesium chloride will fluctuate, and its fluctuating value is between 92% and 97%. The user must analyze the content of MgCl2%, and the supplier's publicity cannot be trusted. Otherwise, it will affect the quantitative relationship between magnesium oxide and magnesium chloride, resulting in back-halogenation and frosting.
When preparing brine with magnesium chloride anhydrous, pay attention to adding magnesium chloride anhydrous to the water for multiple times. Never add water to the magnesium chloride anhydrous, otherwise it will cause a violent bumping phenomenon, causing chlorine-containing water vapor to harm human health.
Because the dissolution of magnesium chloride anhydrous is a violent exothermic reaction, when the percentage concentration of magnesium chloride is 19.13% (equivalent to 21°Bé brine), put 1 part by weight of magnesium chloride anhydrous with 97% MgCl2% content into 4.07 parts by weight of water at once. When dissolving, heat is released rapidly. The temperature of the brine can reach 96℃. This temperature can last for 6 to 8 minutes, and is accompanied by vaporization. The vaporization can last for 35 minutes, and the water vaporization loss rate reaches 9.4%. At this time, the MgCl2% concentration of the brine rose from 19.13% to 20.55%, and the Baume degree of the brine was 21.5°Bé. That is to say, the behavior of preparing brine with magnesium chloride anhydrous is different from the dissolution behavior of industrial magnesium chloride hexahydrate.
When using magnesium chloride anhydrous to prepare brine, you must not use Baumé degree as the quantitative dosage for preparation. The MgCl2% content must be determined to obtain the percentage concentration; according to the amount taken, converted into the amount of magnesium chloride, and the amount of light burnt magnesium chloride used must be calculated with a certain active magnesium oxide content.
The pH value of the brine prepared by using magnesium chloride anhydrous is between 4 and 5. Due to the violent heat release and corrosion in the heated state of the dissolution process, the use of a concrete dissolution tank will cause the dissolution tank to crack and seep out. Therefore, an acid-proof (water glass with a modulus of 2.8~3.2 + sodium fluorosilicate + diabase powder + cast stone particles + furfuryl alcohol) metal dissolution tank or an acid-resistant cement should be used to protect the surface of the cement concrete dissolution tank, avoiding losses caused by the leakage of brine.