Patent ID: 8273320

Claim:
A method for making substantially pure salt from hydro-fracturing wastewater comprising: removing oil from hydro-fracturing wastewater selected from the group consisting of post-drilling flowback water and production brine water; removing solid particulates from the hydro-fracturing wastewater; removing large organic molecules selected from the group consisting of benzene, ethylbenzene, toluene and xylene from the hydro-fracturing wastewater; after removing the oil, the solid particulates, and the large organic molecules, evaporating the hydro-fracturing wastewater to produce a concentrated brine containing from about 15 wt % to about 30 wt % of salt relative to the total weight of the concentrated brine and a first clean water distillate containing less than about 500 ppm of total dissolved solids; recovering the first clean water distillate; sampling the concentrated brine to determine an effective amount of at least one reagent to be added to the concentrated brine to form a precipitate comprising at least one chemical constituent selected from the group consisting of barium and strontium; adding the effective amount of the at least one reagent to the concentrated brine to produce a chemically treated brine and the precipitate; separating the precipitate from the chemically treated brine; after separating the precipitate, introducing the chemically treated brine to a crystallization process using a mechanical vapor recompression evaporator, multi-effect evaporator or a combination thereof to produce sodium chloride solids, a calcium chloride solution and a second clean water distillate containing less than 500 ppm of total dissolved solids; drying the sodium chloride solids to produce over about 98% pure dry sodium chloride; recovering the calcium chloride solution; recovering the second clean water distillate; and using the first and second clean water distillates as source water for hydro-fracturing or returning the first and second clean water distillates to the environment.