MAGNESIUM, BROMINE, AND OTHER PRODUCTS FROM SEA WATER 45 



tower and the resultant solution, containing 20 per cent hydrogen chloride and a 

 small amount of sulfuric acid, is returned to the neutralizers to react with the 

 crude magnesium hydroxide. 



The plant at Freeport has a capacity of 36,000,000 and that at Velasco 72,000,- 

 000 lbs. of 99.9 per cent pure magnesium per year. 



Magnesia and Magnesia Salts from Sea Water 



The Marine Magnesium Products Corporation, established in 1927 at South 

 San Francisco, produces magnesia, milk of magnesia, magnesium carbonate, and 

 other magnesium products from sea water. According to the process used the 



(Courtesy Dorr Co.) 



Fig. 4-6. Plant of the Marine Magnesium Products Corp., South San Francisco, Cali- 

 fornia. Here magnesia, miUc of magnesia, magnesivun carbonate and other magnesium 

 products are made from sea water. 



sea water is given a preliminary pinrification by treatment with a small amount 

 of milk of lime and chlorine. After allowing the treated sea water to deposit sedi- 

 ment by standing in a huge tank, it is filtered through a gravity sand filter, then 

 mixed with more milk of lime and run into another huge precipitating tank. Here, 

 the magnesium hydroxide, formed by the interaction of the magnesium chloride 

 of the sea water and calcixun hydroxide, settles to the bottom and is pumped as a 

 12 per cent slvnry to high tanks with conical bottoms where it is washed with 

 softened fresh water. This reduces its salt content to approximately 0.05 per cent. 

 After passing through a 325-mesh screen the magnesia is pure enough to meet 

 U.S. P. specifications. 



Some of the magnesium hydroxide is carbonated by treatment with CO2, then 

 removed from suspension by filtration and dried. Another portion of the mag- 

 nesia is concentrated by the removal of water by filtration. It is spray-dried and 

 finally calcined to obtain magnesium oxide. 



From each 100 gallons of sea water approximately 34 poimds of magnesium 



