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Process for the treatment of saline water

  • US 7,595,001 B2
  • Filed: 08/27/2003
  • Issued: 09/29/2009
  • Est. Priority Date: 11/05/2002
  • Status: Expired due to Fees
First Claim
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1. A process for treatment of water containing dissolved solids, said process being usable for each of the following types of water:

  • Type 1 water comprising total dissolved solids of 1 to 60 g/L, a Cl

    /HCO3

    ratio of <

    2 and a Cl

    /2SO42−

    ratio of >

    1,Type 2 water comprising total dissolved solids of 1 to 15 g/L, a Cl

    /HCO3

    ratio of ≧

    2 and a Cl

    /2SO42−

    ratio of >

    1,Type 3 water comprising total dissolved solids of 1 to 15 g/L, a Cl

    /HCO3

    ratio of >

    2 and a Cl

    /2SO42−

    ratio of <

    1,Type 4 water comprising total dissolved solids of >

    15 and ≦

    60 g/L, a Cl

    /HCO3

    ratio of >

    5 and a Cl

    /2SO42−

    ratio of >

    7,Type 5 water comprising total dissolved solids of >

    15 and ≦

    60 g/L, a Cl

    /HCO3

    ratio of >

    5 and a Cl

    /2SO42−

    ratio of <

    7,Type 6 water comprising total dissolved solids of >

    60 g/L, a Cl

    /HCO3

    ratio of >

    5 and a Cl

    /2SO42−

    ratio of >

    9, andType 7 water comprising total dissolved solids of >

    60 g/L, a Cl

    /HCO3

    ratio of >

    5 and a Cl

    /2SO42−

    ratio of <

    9,said process comprising the steps of;

    (a) contacting the said water with a first reagent comprising a source of calcium ions selected from the group consisting of calcium oxide, calcium hydroxide, and a combination thereof as a sole agent to cause at least some solids dissolved in the water to react with the first reagent and to form a first solid product and a partially processed water, wherein the water containing dissolved solids is a Type 1 water and the first solid product is precipitated calcium carbonate (PCC) or the water containing dissolved solids is a water of any of Types 2 to 7 and the first solid product is gypsum-magnesium hydroxide mixture (GMH) and wherein the said GMH is further treated by the addition of sulphuric acid to react with 5-50% of the stoichiometric amount of magnesium hydroxide present in the GMH;

    (b) recovering the first solid product from the partially processed water;

    (c) at least partially concentrating the partially processed water or a portion thereof, so as to promote the formation of a precipitate and a mother liquor; and

    (d) recovering the precipitate from the mother liquor as a second product, wherein the water is a water of type 1 and the second product is sodium hydroxide, sodium sulphate, sodium chloride or sodium carbonate;

    wherein the water is a water of any one of types 2, 4, 5, 6 and 7, and the second product is sodium chloride;

    or wherein the water is a water of type 3, and the second product is sodium sulphate.

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