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US 8,912,001 B2Granted
Process for high concentration cation exchanges metathesis
AssigneeCyanco Holding Corporation
InventorsMarcus Rajchel, Michael F. Ray
Life of this patent
Estimating the term…
Abstract
Provided is a method for high concentration cation exchange metathesis of divalent ions such as calcium with univalent ions such as sodium or potassium. Due to the difference between ionic valences between the exchanged ions, the provided process behavior is strongly dependent upon the selection of resin properties and to total solution normality. A combination of resin properties and solution normality is provided to achieve the cation exchange.
Claims31
A method of cation exchange comprising:
- contacting a divalent cation-feed solution with a strong acid cation ion exchange resin having a crosslinking of between 4 and 15% divinylbenzene (DVB) that has been initially loaded with a univalent charged counter ion, wherein the strong acid cation ion exchange resin has been loaded to greater than 90% of the resin capacity with the univalent charged counter ion, and wherein the univalent-loaded ion exchange resin has an initial ionic equivalent composition, the divalent cation-feed solution has a specified ionic equivalent composition, and the resin has a specified activity such that a separation coefficient K′ defined by the ion exchange reaction of divalent ion with univalent-loaded ion exchange resin is greater than or equal to 1.0;
- exchanging the divalent cation with the univalent charged counter ion on the resin to produce a univalent counter ion-product solution and a divalent cation loaded resin, wherein the univalent counter ion-product solution has an ionic equivalent composition that is substantially the same as the initial ionic equivalent composition of the initial univalent-loaded ion exchange resin, and wherein before the last exchanging step, the divalent cation loaded resin is at least 90% divalent-ion form;
- advancing the divalent cation loaded resin counter currently with respect to solution flow through a rinse zone wherein unreacted divalent cation-feed solution is recovered;
- advancing the divalent cation loaded resin to a regeneration zone where the divalent cation loaded resin is contacted with a solution having a univalent exchangeable cation, wherein the divalent cation loaded resin has an initial ionic equivalent composition, the solution having a univalent exchangeable cation has a specified ionic equivalent composition, and the resin has a specified activity such that the separation coefficient, K′, is less than or equal to 1.0, where K′ is defined by the ion exchange reaction of divalent ion with univalent-loaded ion exchange resin, wherein the resin with capacity Q, in gram-equivalents-per-kg, resin bulk density ρr, in kg-per-liter, resin mass action equilibrium constant K for the ion exchange equilibrium defined by absorption of the divalent ion on univalent-form ion exchange resin;
- and the total normality C0, in gram-equivalents-per-liter, of all cations in the divalent cation feed solution or the total solution normality of all cations in the univalent cation feed solution are given by:
- K
- ′
- =
- K
-
- Q
-
-
- ρ
- r
- C
- 0
-
-
- where
-
-
- K
- ′
-
-
- is
-
- :
- (
- Eq
- .
-
- 1
- )
- K
- ′
- =
- (
- 1
- -
- C
- Ca
- C
- 0
- )
- 2
-
- (
- q
- Ca
- Q
- )
- (
- C
- Ca
- C
- 0
- )
-
- (
- 1
- -
- q
- Ca
- Q
- )
- 2
- (
- Eq
- .
-
- 2
- )
- wherein Cca, in gram-equivalents-per-liter, is the solution normality of the divalent cation and qCa, in gram-equivalents-per-kg, is the concentration of divalent species in the resin phase;
- exchanging the divalent cation on the divalent cation loaded resin with the univalent exchangeable cation, producing a resin loaded with the univalent cation and a divalent cation product solution, wherein the divalent cation product solution has an ionic equivalent composition that is substantially the same as the initial ionic equivalent composition of the divalent cation loaded resin.
73 more elements
Dependencies are inferred from the claim text.