Process for recovering sulfate and chloride salts from wastewater, mixed salts, and brines

A method for treating wastewater from a coal to chemical or coal to liquid process, comprising:

• converting coal to chemical or liquid and producing a wastewater;
• pretreating the wastewater to remove at least some contaminants;
• pre-concentrating the wastewater to form a concentrated wastewater;
• removing organics from the concentrated wastewater;
• concentrating the concentrated wastewater to form a salt solution;
• directing the salt solution comprising an alkali metal, chloride, and sulfate to a hydrous salt crystallization unit and crystallizing hydrated sulfate salts to form hydrated sulfate salt crystals comprising sulfate and at least one alkali metal, and a hydrous salt crystallization unit solution;
• melting the hydrated sulfate salt crystals to form an aqueous sulfate solution;
• directing the aqueous sulfate solution to a sulfate crystallization unit and crystallizing anhydrous sulfate salts from the aqueous sulfate solution to form sulfate salt crystals comprising sulfate and at least one alkali metal, and a sulfate crystallization unit solution;
• directing at least a portion of the sulfate crystallization unit solution to the hydrous salt crystallization unit;
• directing at least a portion of the hydrous salt crystallization unit solution or at least a portion of the sulfate crystallization unit solution to a chloride salt crystallization unit and crystallizing chloride salt from the hydrous salt crystallization unit solution or the sulfate crystallization unit solution to form chloride salt crystals comprising chloride and at least one alkali metal, and a chloride salt crystallization unit solution;
• and
• directing at least a portion of the chloride salt crystallization unit solution to the hydrous salt crystallization unit.

A method of recovering sulfate and chloride salts from a salt solution, comprising:

• directing the salt solution comprising an alkali metal, chloride, and sulfate to a hydrous salt crystallization unit and crystallizing hydrated sulfate salts to form hydrated sulfate salt crystals comprising sulfate and at least one alkali metal, and a hydrous salt crystallization unit solution;
• melting the hydrated sulfate salt crystals to form an aqueous sulfate solution;
• directing the aqueous sulfate solution to a sulfate crystallization unit and crystallizing anhydrous sulfate salts from the aqueous sulfate solution to form sulfate salt crystals comprising sulfate and at least one alkali metal, and a sulfate crystallization unit solution;
• directing at least a portion of the sulfate crystallization unit solution to the hydrous salt crystallization unit;
• directing at least a portion of the hydrous salt crystallization unit solution or at least a portion of the sulfate crystallization unit solution to a chloride salt crystallization unit and crystallizing chloride salt from the hydrous salt crystallization unit solution or the sulfate crystallization unit solution to form chloride salt crystals comprising chloride and at least one alkali metal, and a chloride salt crystallization unit solution;
• and
• directing at least a portion of the chloride salt crystallization unit solution to the hydrous salt crystallization unit.

A method of recovering sulfate and chloride salts from a salt solution, comprising:

• directing a solution comprising sodium, chloride, and sulfate to a Glauber's salt crystallizer and crystallizing Na2SO4.10H2O to form Na2SO4.10H2O crystals and a Glauber's salt crystallizer solution;
• melting the Na2SO4.10H2O crystals to form an aqueous sodium sulfate solution;
• directing the aqueous sodium sulfate solution to a Na2SO4 crystallizer and crystallizing sodium sulfate from the aqueous sodium sulfate solution to form Na2SO4 crystals and a Na2SO4 crystallizer solution;
• recycling at least a portion of the Na2SO4 crystallizer solution to the Glauber's salt crystallizer;
• directing at least a portion of the Glauber's salt crystallizer solution or at least a portion of the Na2SO4 crystallizer solution to a NaCl crystallizer and crystallizing NaCl from the Glauber's salt crystallizer solution or the Na2SO4 crystallizer solution to form NaCl crystals and a NaCl crystallizer solution;
• and
• recycling at least a portion of the NaCl crystallizer solution to the Glauber's salt crystallizer.