Chemical treatment and distillation of sea water

Claim 1

IN THE PROCESS FOR PREPARING POTABLE WATER BY DISTILLING SEA WATER IN A TUBULAR HEAT EXCHANGER WHEREIN THE PRODUCTS ARE POTABLE WATER AND STILL WASTE, WHEREIN SULFURIC ACID IS ADDED TO PREVENT THE DEPOSIT OF SCALE ON THE HEAT EXCHANGERS TUBES AND CONCENTRATES IN THE STILL WASTE, AND WHEREIN THE SULFURIC ACID IN SAID STILL WASTE IS NEUTRALIZED WITH LIME BEFORE DISCHARGING SAID STILL WASTE, THE IMPROVEMENT COMPRISING: (A) ADDING SUFFICIENT LIME TO SAID STILL WASTE TO NEUTRALIZE SAID WASTE AND ADJUST ITS PH OF SAID WASTE TO ABOUT 7.0-9.5; (B) ADDING CULCICUM CHLORIDE TO SAID NEUTRALIZED WASTE IN SUCH QUANTITY THAT THE TOTAL CALCIUM ION CONCENTRATION IN THE RESULTING MIXTURE IS SUBSTANTIALLY EQUIVALENT STOICHIOMETRICALLY TO THE SULFATE ION CONCENTRATION IN SAID MIXTUE, THEREBY PRECIPITATING SUBSTANTIALLY PURE GYPSUM; (C) SEPARATING THE THUS PRECIPITATED GYPSUM FROM THE THUS TREATED STILL WASTE; (D) ADDING SUFFICIENT LIME TO THE THUS TREATED STILL WASTE TO ADJUST THE PH THEREOF TO ABOUT 10.4, THEREBY PRECIPITATING MAGNESIUM HYDROXIDE; (E) SEPARATING THE THUS PRECIPITATED MAGNESIUM HYDROXIDE FROM THE THUS TREATED STILL WASTE TO LEAVE A REMAINING EFFLUENT.