Separation of manganese from brine

A method for the selective precipitation and recovery of manganese and zinc from a geothermal brine, the method comprising the steps of:

• contacting the geothermal brine with ammonia at a pH of between about 7 and 8.6 to selectively precipitate manganese and produce a manganese depleted brine solution, without the co-precipitation of other metals present in the geothermal brine;
• separating the precipitated manganese from the manganese depleted brine solution;
• contacting the manganese depleted brine solution with air and lime until a pH of less than 8 is achieved to selectively precipitate zinc from the manganese depleted brine solution, thereby producing a manganese and zinc depleted brine solution;
• separating the precipitated zinc from the manganese and zinc depleted brine solution;
• and
• injecting the manganese and zinc depleted brine solution into a geothermal well.

A method for the selective removal of manganese and zinc from a geothermal brine, the method comprising the steps of:

• contacting the geothermal brine with lime until a pH of between about 7.5 and 8 is achieved, thereby selectively precipitating manganese and zinc from a depleted geothermal brine solution;
• separating the manganese and zinc precipitates from the depleted geothermal brine solution;
• contacting the manganese and zinc precipitates with an ammonium salt at a pH of at least about 8.8 to dissolve the zinc precipitate and produce a zinc containing solution;
• separating the manganese precipitate from the zinc containing solution;
• contacting the zinc containing solution with air, until the ammonia is removed and adding lime to maintain the pH at between about 7 and 8.5 to precipitate zinc hydroxide or zinc hydroxide derivatives;
• and isolating the zinc precipitate.

A method for the separation and isolation of manganese from a manganese containing brine solution, the method comprising the steps of:

• contacting a manganese containing brine solution with ammonia in a reaction tank at a pH of about 6.5 to 8.5 to selectively precipitate manganese from the solution and produce a manganese depleted brine solution, said manganese precipitate having a purity of at least about 95%;
• separating the manganese precipitate from the manganese depleted brine solution;
• contacting the manganese depleted brine solution, which includes ammonia, with air to separate the brine solution and the ammonia;
• collecting an ammonia and air stream and an ammonia-free manganese depleted brine stream;
• separating the air and ammonia to produce an ammonia recycle stream;
• and recycling the ammonia recycle stream to the step of contacting the manganese containing brine solution.

A method for the selective removal of manganese and zinc from a geothermal brine, the method comprising the steps of:

• contacting the geothermal brine with ammonia at a pH of between about 7 and 8.6 to selectively precipitate manganese and produce a manganese depleted brine solution, without co-precipitation of other metals present in the geothermal brine;
• separating the precipitated manganese from the manganese depleted brine solution;
• contacting the manganese depleted brine solution with a gas and an ion exchange agent until a pH of less than 8 is achieved to selectively precipitate zinc from the manganese depleted brine solution, thereby producing a manganese and zinc depleted brine solution;
• separating the precipitated zinc from the manganese and zinc depleted brine solution;
• and
• injecting the manganese and zinc depleted solution into a geothermal well.