The proposed process
basically combines two decades old
processes (Solvay and Dow Magnesium) for the manufacture of soda ash and
magnesium, respectively into a single process that also produces “partially-desalinated”
water. It does so by subjecting salt brines first, to ammonia causing two
simultaneous actions: 1) the absorption of ammonia forming what is called
“ammoniated brine”, and 2) the precipitation of magnesium ions, found in the
brine, as magnesium hydroxide, Mg(OH)2, which is filtered and separated.
Next, carbon dioxide is introduced through the bulk of ammoniated brine, brine
saturated with ammonia, causing the chemical conversion of both Na and Cl﹣ into NaHCO3 and NH4Cl, respectively. Soda ash
(Na2CO3) and ammonium chloride (NH4Cl) come as
products, along with partially desalinated water. This process is identified as
“brine desalting”,
because of the drastic reduction of the salt content in brine. This part was
experimentally tested before by the author and coworkers. Magnesium chloride
(MgCl2) is obtained, next, by reacting ammonium chloride (NH4Cl) with
Mg(OH)2. In this double reaction, ammonia will be regenerated and
recycled back to the process: 2NH4Cl Mg(OH)2 à Mg(Cl)2 2NH3 2H2O. Magnesium chloride is the raw material for making magnesium metal. This
makes an additional economic value to the proposed process. The present
contribution offers this conceptual scheme as an
amalgamation of both Solvay/Dow (Magnesium)
processes.
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