Patent ID: 8158097

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