Multivalent cation-containing copolymer, process for production thereof and use thereof to treating aqueous dispersions

Abstract

A process for producing a multivalent cation containing copolymer, containing: contacting a multivalent cation containing ethylenically unsaturated acid and at least one comonomer to produce a monomer mixture comprising the multivalent cation containing ethylenically unsaturated acid present in an amount in the range of from about 5% to about 65% by weight; and contacting the monomer mixture with a redox initiator comprising a reducing compound and an oxidising compound and contacting the monomer mixture with a thermal initiator to cause the multivalent cation containing ethylenically unsaturated acid and the at least one comonomer to react to produce the multivalent cation containing copolymer, wherein the thermal initiator is used in the range 100 to 5000 ppm.

Claims

1. A process for producing a multivalent cation containing copolymer, which copolymer is derived from one or more ethylenically unsaturated acids, the copolymer having the following characteristics: (a) an intrinsic viscosity of at least about 3 dl/g when measured in 1 M NaCl solution at 25° C.; (b) the copolymer is derived from a monomer mixture comprising an ethylenically unsaturated acid and at least one comonomer, the ethylenically unsaturated acid present in an amount in the range of from about 5% to about 65% by weight; and (c) a residual comonomer content is less than 1000 ppm when the comonomer is an acrylamide, comprising: contacting a multivalent cation containing ethylenically unsaturated acid and at least one comonomer to produce a monomer mixture comprising the multivalent cation containing ethylenically unsaturated acid present in an amount in the range of from about 5% to about 65% by weight; and contacting the monomer mixture with a redox initiator comprising a reducing compound and an oxidising compound and contacting the monomer mixture with a thermal initiator to cause the multivalent cation containing ethylenically unsaturated acid and the at least one comonomer to react to produce the multivalent cation containing copolymer, wherein the thermal initiator is used in the range 100 to 5000 ppm.

2. The process of claim 1, wherein the multivalent cation containing ethylenically unsaturated acid is a multivalent cation containing diacrylate.

3. The process of claim 1, wherein the thermal initiator comprises an azo compound.

4. The process of claim 1, wherein the thermal initiator is selected from the group consisting of azobisisobutyronitrile (AIBN), 4,4′-azobis-(4-cyanovalereic acid) (ACVA) and any mixture thereof.

5. The process of claim 1 wherein the thermal initiator is used in the range 200 to 2000 ppm.

6. The process of claim 1, in which the redox initiator is in the range of 1 to 100 ppm.

7. The process of claim 1, in which the ratio of the reducing agent to oxidising agent is in the range of 5:1 to 1:2.

8. The process of claim 1, wherein the reducing compound is selected from the group consisting of sodium sulfite, sulfur dioxide, sodium metabisulfite and any mixture thereof.

9. The process of claim 1, wherein the oxidising compound is selected from the group consisting of ammonium persulfate, tertiary butyl hydroperoxide and any mixture thereof.

10. The process of claim 1, wherein the multivalent cation containing ethylenically unsaturated acid is prepared by adding water and glacial acrylic acid to a reaction vessel and then adding an aqueous suspension of Ca(OH)2 to this mixture slowly under cooling and pH control until pH 6.0±0.1 is reached.

11. The process of claim 1, wherein Na-hypophosphite is added to the monomer mixture.

12. The process of claim 1, wherein the pH of the monomer mixture is 6.0±0.1.

13. The process of claim 1, wherein the polymerisation is initiated at a temperature of 0° C.±1.0° C.

14. The process of claim 1, wherein the multivalent cation containing copolymer is in the form of a calcium copolymer.

15. The process of claim 1, wherein the multivalent cation containing copolymer is in the form of a magnesium copolymer.

16. The process of claim 1, wherein the at least one comonomer is selected from the group consisting of acrylamide, methacrylamide and any mixture thereof.

17. The process of claim 1, wherein the at least one comonomer is acrylamide.

18. The process of claim 1, wherein the ethylenically unsaturated acid is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, acrylamido tertiary butyl sulfonic acid (ATBS) and any mixture of two or more of these.

19. The process of claim 1, wherein the ethylenically unsaturated acid is acrylic acid.

20. The process of claim 1, wherein the ethylenically unsaturated acid is acrylic acid and the at least one comonomer is acrylamide.

21. The process of claim 1, wherein the ethylenically unsaturated acid is present in an amount in the range of from about 15% to about 65% by weight.

22. The process of claim 1, wherein the ethylenically unsaturated acid is present in an amount in the range of from about 20% to about 65% by weight.

23. The process of claim 1, wherein the ethylenically unsaturated acid is present in an amount in the range of from about 35% to about 65% by weight.

24. The process of claim 1, wherein the intrinsic viscosity of the multivalent cation containing copolymer is in the range of from about 4 to about 25 dl/g when measured at 1 M NaCl solution at 25° C.

25. The process of claim 1, wherein the intrinsic viscosity of the multivalent cation containing copolymer is in the range of from about 4 to about 20 dl/g when measured at 1 M NaCl solution at 25° C.

26. The process of claim 1, wherein the intrinsic viscosity of the multivalent cation containing copolymer is in the range of from about 4 to about 15 dl/g when measured at 1 M NaCl solution at 25° C.

27. The process of claim 1, wherein the multivalent cation containing copolymer is in solid form.

28. The process of claim 1, wherein the multivalent cation containing copolymer is in particulate form.

29. The process of claim 1, wherein the multivalent cation containing copolymer is in powder form.

30. The process of claim 1, wherein the multivalent cation containing copolymer is in bead form.

31. The process of claim 1, wherein the residual comonomer (ACM) content of the multivalent cation containing copolymer is less than about 500 ppm when the comonomer is acrylamide.

32. The process of claim 1, wherein the residual comonomer (ACM) content of the multivalent cation containing copolymer is in the range of from about 300 ppm to about 500 ppm when the comonomer is an acrylamide.

33. The process of claim 1, wherein the multivalent cation containing copolymer is water-soluble.

34. The process of claim 33, wherein the multivalent cation containing copolymer has a gel content measurement of less than 50% gel.

35. The process of claim 1, wherein the multivalent cation containing copolymer has an anionic content in the range of from about 20 to about 60 weight percent.

36. The process of claim 1, wherein the multivalent cation containing copolymer has an anionic content in the range of from about 25 to about 60 weight percent.

37. The process of claim 1, wherein the multivalent cation containing copolymer has an anionic content in the range of from about 30 to about 60 weight percent.

38. The process of claim 1, wherein the multivalent cation containing copolymer has an anionic content in the range of from about 40 to about 60 weight percent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will be described with reference to the accompanying drawings, wherein like reference numerals denote like parts, and in which:

(2) FIGS. 1-2 illustrate results of testing of polymers produced in Examples 1-6 to treat a slurry of mature fine tailings (MFT);

(3) FIG. 3 illustrates results of testing of polymers produced in Examples 8 and 9 to treat a slurry of mature fine tailings (MFT); and

(4) FIG. 4 illustrates results of testing of polymers produced in Examples 14 to treat a slurry of mature fine tailings (MFT).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) The present invention relates to a multivalent cation containing copolymer derived from one or more ethylenically unsaturated acids, the copolymer having the following characteristics: (a) an intrinsic viscosity of at least about 3 dl/g when measured in 1 M NaCl solution at 25° C.; (b) the copolymer is derived from a monomer mixture comprising an ethylenically unsaturated acid and at least one comonomer, the ethylenically unsaturated acid present in an amount in the range of from about 5% to about 65% by weight; and (c) a residual comonomer content is less than 1000 ppm when the comonomer is an acrylamide. Preferred embodiments of this copolymer may include any one or a combination of any two or more of any of the following features: the copolymer is in the form of a calcium copolymer (by “calcium copolymer” is meant the aforementioned copolymer in which the multivalent cation is calcium—this may be termed the calcium salt of the copolymer—in this case the calcium cation may partially or fully neutralise the acid groups of the copolymer); the copolymer is in the form of a magnesium copolymer (by “magnesium copolymer” is meant the aforementioned copolymer in which the multivalent cation is magnesium—this may be termed the magnesium salt of the copolymer—in this case the magnesium cation may partially or fully neutralise the acid groups of the copolymer); the at least one comonomer is selected from the group consisting acrylamide, methacrylamide and any mixture thereof; the at least one comonomer is acrylamide; the ethylenically unsaturated acid is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, acrylamido tertiary butyl sulfonic acid (ATBS) and any mixture of two or more of these; the ethylenically unsaturated acid is selected from the group consisting of acrylic acid, methacrylic acid, acrylamido tertiary butyl sulfonic acid (ATBS) and any mixture of two or more of these; the ethylenically unsaturated acid is acrylic acid; the ethylenically unsaturated acid present in an amount in the range of from about 15% to about 65% by weight; the ethylenically unsaturated acid present in an amount in the range of from about 20% to about 65% by weight; the ethylenically unsaturated acid present in an amount in the range of from about 35% to about 65% by weight; the instrinsic viscosity in the range of from about 4 to about 25 dl/g when measured in 1 M NaCl solution at 25° C.; the instrinsic viscosity in the range of from about 4 to about 20 dl/g when measured in 1 M NaCl solution at 25° C.; the instrinsic viscosity in the range of from about 5 to about 15 dl/g when measured in 1 M NaCl solution at 25° C.; the copolymer is in solid form; the copolymer is in particulate form; the copolymer is in spherical particulate form; the copolymer is in powder form; the copolymer is in bead form; the copolymer is in the form of a reverse-phase emulsion; the copolymer is in the form of a reverse-phase dispersion; the copolymer is in the form of an aqueous solution; the copolymer is in the form of an aqueous dispersion; the copolymer is linear; the copolymer is branched; the copolymer is cross-linked; the residual comonomer (ACM) content is less than about 500 ppm when the comonomer is an acrylamide; the residual comonomer (ACM) content is in the range of from about 300 pmm to about 500 ppm when the comonomer is an acrylamide; the copolymer is water soluble; the copolymer is in substantially pure form; the copolymer is in isolated form; the copolymer has an anionic content in the range of from about 20 to about 65% by weight; the copolymer has an anionic content in the range of from about 25 to about 65% by weight; the copolymer has an anionic content in the range of from about 30 to about 65% by weight; and/or the copolymer has an anionic content in the range of from about 40 to about 60% by weight.

(6) In one preferred form, the multivalent cation containing copolymer of the present invention is water soluble. By water soluble we mean that the copolymer has a gel content measurement of less than 50% gel. The gel content measurement is described below.

(7) Preferably, the present multivalent cation containing copolymer is used in a process to treat an aqueous slurry comprising particulate material. The term “treat” is intended to have a broad meaning and includes thickening, sedimentation, dewatering, compaction, consolidation, coagulation, flocculation and the like. Preferred embodiments of this process may include any one or a combination of any two or more of any of the following features: the process comprises the step of contacting the aqueous slurry with the above multivalent cation containing copolymer; the process comprises the step of contacting the aqueous slurry with an aqueous solution comprising the above multivalent cation containing copolymer; the aqueous slurry comprises tailings; the aqueous slurry comprises mature fine tailings (MET); the aqueous slurry comprises fluid fine tailings (FFT); the aqueous slurry comprises thin fine tailings (TFT); the aqueous slurry comprises whole fine tailings (WT); the process results in the thickening of the solid particulates; the process results in the sedimentation of the solid particulates; the process results in the dewatering of the solid particulates; the process results in the compaction and/or consolidation of the solid particulates; the process results in the coagulation of the solid particulates; and/or the process results in the flocculation of the solid particulates.

(8) Preferred embodiments of the present application will be described with reference to the following Examples which should not be used to construe or limit the scope of the invention.

EXAMPLES

(9) In the Examples, the following materials were used.

(10) Monomers:

(11) ##STR00001##

(12) For all calculations (Ca).sub.0.5AA (short Ca-AA) was used instead of Ca(AA).sub.2 and (Mg).sub.0.5AA (short Mg-AA) was used instead of Mg(AA).sub.2.

(13) Chemicals:

(14) ACM Acrylamide

(15) Ca-AA Calcium acrylate [(Ca).sub.0.5AA]

(16) Mg-AA Magnesium acrylate [(Mg).sub.0.5AA]

(17) Na-A A Sodium acrylate [Na AA]

(18) Na-hypophosphite sodium hypophosphite

(19) sodium metabisulphite
tBHP tert-Butyl hydroperoxide
AIBN Azobisisobutyronitrile
ACVA 4,4′ Azobis (4-cyano valeric acid)
Trilon™ C D ethylene triamino pentaacetate

(20) The polymers were subject to various tests using the following methodology.

(21) Determination of Solid Content

(22) Approximately 1 g of polymer is weighed into an aluminium pan and put into the drying oven for 3 hours at 110° C. The mass difference before drying and after drying is determined and the solid content of the polymer is calculated in percent. This procedure is repeated twice and the average value of all three measurements is calculated.

(23) IV (Intrinsic Viscosity) Measurement, Visual Solubility Evaluation, and Gel Content Determination Including Solution Preparation

(24) Preparation of Stock Solution:

(25) 1.0 g of polymer is weight in a bottle and 199 nil of deionized water are added. This mixture is mixed for 4 hours on a tumble wheel at ambient temperature (25° C.).

(26) Visual Solubility Evaluation:

(27) The solubility of this stock solution is evaluated visually in terms of potential undissolved polymer particles or gel particles in the solution.

(28) Gel Content Determination:

(29) The gel content is determined by filtering the stock solution (preparation see above) through a sieve with a 190 μm mesh size. The residue which stays in the filter is washed, recovered, dried (110° C.) and weighed, and the percentage of undissolved polymer is calculated (weight of dry residue from the filter [g]/weight of dry polymer before filtration [g]). Where necessary, this provides a quantifiable confirmation of the visual solubility evaluation.

(30) Preparation of Diluted Measuring Solutions for IV Measurements:

(31) 4.0, 8.0, 12.0, and 16.0 g, respectively, of the stock solution (preparation see above) are weighed into 100 ml volumetric flasks. 50 ml of sodium chloride solution (2 M) is added by pipette and the flask is then filled to the 100 ml mark with dionized water and this mixture is shaken for 5 minutes until homogeneous.

(32) IV Measurement:

(33) The polymer solutions are transferred to an Ubbelohde viscometer and the IV is measured. The measurement carried out at 25° C. at the capillary viscometer Lauda iVisc.

(34) Residual Acrylamide Determination

(35) Chemicals:

(36) Acrylamide (Standard, purity >99.5%);

(37) water, deionized;

(38) orthophosphoric acid (85%);

(39) isopropanol; and

(40) methanol (HPLC-quality).

(41) Chromatographic Conditions:

(42) TABLE-US-00001 machine high-pressure liquid chromatographs with variable UV-detectors, Waters 2695 and 2487 column Machery-Nagel Nucleosil 100-5 C.sub.18, 250 × 4.6 mm column size 250 mm × 4.6 mm mobile 50 ppm orthophosphoric acid phase in water/methanol (94/6 vol-%) flow rate 0.8 mL/min temperature room of column temperature detection UV = 210 nm injection 5 μL volume
Preparation of Standard Acrylamide Solutions:

(43) 20.0 mg of acrylamide was weighed into a 100 ml volumetric flask. Subsequently a mixture of isopropanol and water (70/30) was added to the 100 nil mark. Out of this stock solution, several measurement solutions were prepared by means of a dilution series (e.g., 0.2 mL/50 mL, 1/50 mL, 5/50 mL 10/50 mL and 15 mL/50 mL).

(44) Sample Preparation:

(45) 1.00 g of polymer was weight in a 100 mL glass bottle and 50 mL of a mixture of isopropanol and water (70/30) were added and stirred for 2 hours. This mixture was filtered (nylon filter with pore size: 0.45 μm) and placed in a HPLC-vial.

(46) Measurement:

(47) The HPLC measurements are done by high-pressure liquid chromatographs with variable UV detectors, Waters 2695 and 2487. The signals of the standard acrylamide solutions were utilized to prepare a calibration curve with the software “Empower”. By means of the calibration curve the residual acrylamide value in the samples is calculated

Example 1—40 wt % Ca Diacrylate Polymer (IV=15)

(48) Water (1092.6 g) and glacial acrylic acid (286.3 g) are added to a reaction vessel. Next, 30 wt % aqueous suspension of Ca(OH).sub.2 (˜477 g) is added to this mixture slowly under cooling and pH control until pH 6.0±0.1 is reached. 51 wt % aqueous solution of Acrylamide (1085.6 g), Trilon™ C (4.6 g), defoamer (Xiameter™ APE-0400), 10 wt % aqueous solution of Na-hypophosphite (0.45 g), and 4% ACVA in 5 wt % NaOH solution (22.5 g) are added and the pH is main adjusted with acetic acid to pH 6.0±0.1

(49) Next, the additional water is added to reach the monomer solids of 30.5% (for calculation ACM Ca-AA, and unneutralised AA are taken into account). The reaction mixture is cooled down during degassing for 45 minutes. When a temperature of about −1° C. is reached, 4% AIBN solution in methanol (22.5 g) and 1% aqueous solution of tBHP (1.5 g) solutions are added to the monomer solution and the degassing is continued for 10 minutes.

(50) Subsequently, at a temperature of 0° C.±1.0° C., the polymerization is initiated by adding the 1% aqueous solution of sodium metabisulphite solution (3.0 g). After the polymerization, the wet gel was placed in a heated cabinet at 80° C. for 2 hours. Next, the wet gel is minced, subsequently dried in a fluid bed dryer (65° C. for 2 hours), and finally ground to obtain a white/yellowish powder.

(51) The polymer had the following characteristics: IV: 15 dl/g Gel content: 3% Visual solubility: good Solid content: 89% Residual acrylamide: 400 ppm

Example 2-40 wt % Ca Diacrylate Polymer (IV=5)

(52) Water (135.2 g) and glacial acrylic acid (38 g) are added to a reaction vessel. Next, 30 wt % aqueous suspension of Ca(OH).sub.2 (˜67 g) is added to this mixture slowly under cooling and pH control until pH 6.0±0.1 is reached. 51 wt % aqueous solution of Acrylamide (144 g), 5 wt % aqueous solution of Trilon™ C (2.9 g), defoamer (Xiameter™ AFE-0400), 10 wt % aqueous solution of Na-hypophosphite (0.6 g), and 4% ACVA in 5 wt % NaOH solution (3 g) are added and the pH is again adjusted with acetic acid to pH 6.0±0.1.

(53) Next, the additional water is added to reach the monomer solids of 30.5% (for calculation ACM, Ca-AA, and unneutralised AA are taken into account). The reaction mixture is cooled down during degassing for 45 minutes. When a temperature of about −1° C. is reached, 4% AIBN solution in methanol (3 g) and 1% aqueous solution of tBHP (0.32 g) are added to the monomer solution and the degassing is continued for 2 minutes.

(54) Subsequently, at a temperature of 0° C.±1.0° C., the polymerization is initiated by adding the 1% aqueous solution of sodium metabisulphite solution (0.64 g). After the polymerization, the wet gel was placed in a heated cabinet at 80° C. for 2 hours. Next, the wet gel is minced, subsequently dried in a fluid bed dryer (65° C. for 2 hours), and finally ground to obtain a white/yellowish powder.

(55) The polymer had the following characteristics: IV: 5.7 dl/g Gel content: not determined Visual solubility: good Solid content: 81.6% Residual acrylamide: 259 ppm

Example 3-40 wt % Ca Diacrylate Polymer (IV=11)

(56) Water (135 g) and glacial acrylic acid (38 g) are added to a reaction vessel. Next, 30 wt % aqueous suspension of Ca(OH).sub.2 (˜66 g) is added to this mixture slowly under cooling and pH control until pH 6.0±0.1 is reached. 51 wt % aqueous solution of Acrylamide (144 g), 5 wt % aqueous solution of Trilon™ C (2.9 g), defoamer (Xiameter™ AFE-0400), 10 wt % aqueous solution of Na-hypophosphite (1.4 g), and 4% ACVA in 5 wt % NaOH solution (3 g) are added and the pH is again adjusted with acetic acid to pH 6.0±0.1.

(57) Next, the additional water is added to reach the monomer solids of 30.5% (for calculation ACM, Ca-AA, and unneutralised AA are taken into account). The reaction mixture is cooled down during degassing for 45 minutes. When a temperature of about −1° C. is reached, 4% AIBN solution in methanol (3 g) and 1% aqueous solution of tBHP (0.2 g) are added to the monomer solution and the degassing is continued for 2 minutes.

(58) Subsequently, at a temperature of 0° C. 1.0° C., the polymerization is initiated by adding the 1% aqueous solution of sodium metabisulphite solution (0.40 g). After the polymerization, the wet gel was placed in a heated cabinet at 80° C. for 2 hours. Next, the wet gel is minced, subsequently dried in a fluid bed dryer (65° C. for 2 hours), and finally ground to obtain a white/yellowish powder.

(59) The polymer had the following characteristics: IV: 10.8 dl/g Gel content: not determined Visual solubility: good Solid content: 86.9% Residual acrylamide: 240 ppm

Example 4—40 wt % Ca Diacrylate Polymer Beads (IV=3)

(60) 600 g solvent oil D40, 5.0 g Span™ 80, and 1.4 g phenothiazine were weighed into a 2 L double wall reactor and the reactor was heated to 35° C. whilst purging with nitrogen for 90 minutes.

(61) The aqueous monomer phase was prepared in a separate beaker. Specifically, 80 g water and 40.7 g glacial acrylic acid was weighed into the beaker and approximately 71.5 g calcium hydroxide (30 wt % aqueous suspension) was added dropwise with cooling to neutralize the acrylic acid until a pH 6.0 is reached. Next, 154.3 g acrylamide (51 wt % aqueous solution), 0.6 g Trilon™ C, and 0.9 g sodium hypophosphite (10 wt % aqueous solution) was added to the mixture. The pH is re-adjusted to 6.0 and the additional water (4.2 g) was added to reach a solid content of 35.7%. In addition, 1.44 g V-50™ (10% aqueous solution) and 2.88 g sodium sulfite (1% aqueous solution) were added into the monomer phase.

(62) The aqueous monomer phase and the oil phase were combined in the double wall reactor and the stirring speed was adjusted to 350 rpm. To start the reaction 5.76 g tBHP (1% aqueous solution) was added. After reaching the temperature maximum, the mixture was stirred further for 30 min. The water was removed by an azeotropic distillation at 75° C. and 50 mPa. The reaction mixture was cooled down to 30° C., removed from the reactor and the polymer beads were filtered out of the oily reaction mixture, washed with acetone and dried in the drying oven at 40° C. for 6 hours, obtaining dry polymer beads.

(63) The polymer had the following characteristics: IV: 2.9 dl/g Gel content: not determined Visual solubility: good Solid content: 84.1% Residual acrylamide: not determined

Example 5—60 wt % Ca Diacrylate Polymer (IV=

(64) Water (135 g) and glacial acrylic acid (57 g) are added to a reaction vessel. Next, 30 wt % aqueous suspension of Ca(OH).sub.2 (˜100 g) is added to this mixture slowly under cooling and pH control until pH 6.0±0.1 is reached. 51 wt % aqueous solution of Acrylamide (96 g), 5 wt % aqueous solution of Trilon™ C (2.9 g), defoamer (Xiameter™ AFE-0400), 10 wt % aqueous solution of Na-hypophosphite (0.5 g), and 4% ACVA in 5 wt % NaOH solution (3 g) are added and the pH is again adjusted with acetic acid to pH 6.0±0.1.

(65) Next, the additional water is added to reach the monomer solids of 30.5% (for calculation ACM, Ca-AA, and unneutralised AA are taken into account). The reaction mixture is cooled down during degassing for 45 minutes. When a temperature of about −1° C. is reached, 4% AIBN solution in methanol (3 g) and 1% aqueous solution of tBHP (0.2 g) are added to the monomer solution and the degassing is continued for 2 minutes.

(66) Next, at a temperature of 0° C.±1.0° C., the polymerization is initiated by adding the 1% aqueous solution of sodium metabisulphite solution (0.40 g). After the polymerization, the wet gel was placed in a heated cabinet at 80° C. for 2 hours. Next, the wet gel is minced, subsequently dried in a fluid bed dryer (65° C. for 2 hours), and finally ground to obtain a white/yellowish powder.

(67) The polymer had the following characteristics: IV: 4.4 dl/g Gel content: not determined Visual solubility: good Solid content: 84.3% Residual acrylamide: 80 ppm

Example 6—60 wt % Ca Diacrylate Polymer (IV=11)

(68) Water (135 g) and glacial acrylic acid (57 g) are added to a reaction vessel. Next, 30 wt % aqueous suspension of Ca(OH).sub.2 (˜99 g) is added to this mixture slowly under cooling and pH control until pH 6.0±0.1 is reached. 51 wt % aqueous solution of Acrylamide (96 g), 5 wt % aqueous solution of Trilon™ C (2.9 g), defoamer (Xiameter™ AFE-0400), 10 wt % aqueous solution of Na-hypophosphite (0.8 g), and 4% ACVA in 5 wt % NaOH solution (3 g) are added and the pH is again adjusted with acetic acid to pH 6.0±0.1.

(69) Next, the additional water is added to reach the monomer solids of 30.5% (for calculation ACM, Ca-AA, and unneutralised AA are taken into account). The reaction mixture is cooled down during degassing for 45 minutes. When a temperature of about −1° C. is reached, 4% AIBN solution in methanol (3 g) and 1% aqueous solution of tBHP (0.2 g) are added to the monomer solution and the degassing is continued for 2 minutes.

(70) Next, at at a temperature of 0° C.±1.0° C., the polymerization is initiated by adding the 1% aqueous solution of sodium metabisulphite solution (0.40 g). After the polymerization, the wet gel was placed in a heated cabinet at 80° C. for 2 hours. Next, the wet gel is minced, subsequently dried in a fluid bed dryer (65° C. for 2 hours), and finally ground to obtain a white/yellowish powder.

(71) The polymer had the following characteristics: IV: 11.7 dl/g Gel content: not determined Visual solubility: good Solid content: 87.4% Residual acrylamide: 160 ppm

Example 7

(72) The polymers produced in Examples 1-6 were tested as flocculants in the treatment and dewatering of a slurry of mature fine tailings (MFT) from an oil sands mining operation. The MFT sample used had a total solids content of 33% and overall clay content of 26%.

(73) The following protocol was used during the testing.

(74) Each of the polymers were prepared as 0.5% wt/vol solutions in process water from the oil sands mining operation. Typically this water has a similar chemical composition to the aqueous phase of the MFT slurry.

(75) Prior to testing, the sample of MFT slurry should be mixed under high shear conditions to breakdown any thixotropic gel structure which may have formed in the sample. The correct amount of mixing required to achieve this may be determined by monitoring the yield shear stress of the material, and sufficient mixing should be given until the yield stress value is minimised and stable.

(76) A 300 g aliquot of the MFT slurry is placed in a 600 ml beaker and sheared at 500 rpm with a flat blade impeller until minimum slurry yield stress is achieved as described above. Reduce the mixer speed to 320 rpm and immediately add the required amount of flocculant solution to the MFT slurry. Mixing is continued until the sample is conditioned at the visual point of optimum flocculation/net water release (NWR), at which point the mixer is stopped. The time required to reach the point of optimum conditioning is recorded, and it may differ for different polymer types and dosages.

(77) The beaker is removed from the stirrer and any remaining slurry left on the impeller is scraped off into the beaker. The yield stress of the treated material is immediately recorded using a suitable rheometer (e.g., Haake Rheometer with a vane spindle).

(78) The treated material is transferred into a 2″ slump collar, located on top of a 1 mm mesh sieve and fitted with a collection base. The beaker is scraped clean and the solids are added to those in the collar. Record the total amount of solids & water transferred from the beaker to the sieve. The slump collar is removed, and timing is started.

(79) 24 hours after the material is slumped, the volume of water released from the solids, and the yield stress of the remaining solids on the sieve is measured and recorded.

(80) NWR (%) is calculated for each data point is calculated using the following equation:

(81) $\mathrm{NWR}\left(\%\right)=\left[\frac{\begin{array}{c}\mathrm{Total}\mathrm{volume}\mathrm{of}\mathrm{water}\mathrm{release}\left(\mathrm{ml}\right)-\\ \mathrm{Volume}\mathrm{of}\mathrm{polymer}\mathrm{solution}\mathrm{added}\left(\mathrm{ml}\right)\end{array}}{\begin{array}{c}\mathrm{Weight}\mathrm{of}\mathrm{slurry}\mathrm{used}\left(g\right)\times \\ \{1-\frac{\mathrm{MFT}\mathrm{Slurry}\mathrm{Solids}\mathrm{Content}\left(\%w/w\right)}{100}\end{array}}\right]\times 100$
Results:

(82) Table 1 shows the test results obtained for the 40% calcium diacrylate polymers (examples 1 to 4) and Table 2 shows the test results obtained for the 60% calcium diacrylate polymers (examples 5 and 6). The 24 hour NWR data is also represented graphically in FIGS. 1 and 2.

(83) The results show that the calcium diacrylate polymers are able to effectively treat, flocculate and dewater the oil sands, MFT slurry.

Example 8—21% wt Ca Diacrylate Polymer (IV=10.1)

(84) Water (140.4 g) and glacial acrylic acid (20.3 g) are added to a reaction vessel. Next, 30 wt % aqueous suspension of Ca(OH).sub.2 (˜40 g) is added to this mixture slowly under cooling and pH control until pH 6.0±0.1 is reached. 51 wt % aqueous solution of Acrylamide (188.9 g), 5 wt % aqueous solution of Trilon™ C (2.9 g), defoamer (Xiameter™ AFE-0400), 1 wt % aqueous solution of Na-hypophosphite (0.8 g), and 4% ACVA in 5 wt % NaOH solution (3 g) are added and the pH is again adjusted with acetic acid to pH 6.0±0.1.

(85) Next, addition water is added to reach the monomer solids of 30.5% (for calculation ACM, Ca-AA, and unneutralised AA are taken into account). The reaction mixture is cooled down during degassing for 45 minutes. When a temperature of about −1° C. is reached, 4% AIBN solution in methanol (3 g) and 1% aqueous solution of tBHP (0.32 g) are added to the monomer solution and the degassing is continued for 2 minutes.

(86) Next, at a temperature of 0° C.±1.0° C., the polymerization is initiated by adding the 1% aqueous solution of sodium metabisulphite solution (0.64 g). After the polymerization, the wet gel was placed in a heated cabinet at 80° C. for 2 hours. Next, the wet gel is minced, subsequently dried in a fluid bed dryer (55° C. for 2 hours), and finally ground to obtain a white/yellowish powder.

(87) The polymer had the following characteristics: IV: 10.1 dl/g Gel content: 0% Visual solubility: good Solid content: 90.4% Residual acrylamide: 570 ppm

Example 9-19.5% wt Mg Diacrylate Polymer (IV=10.2)

(88) Water (130.7 g) and glacial acrylic acid (20.5 g) are added to a reaction vessel. Next, 20 wt % aqueous suspension of Mg(OH).sub.2 (˜41.4 g) is added to this mixture slowly under cooling and pH control until pH 6.0±0.1 is reached. 51 wt % aqueous solution of Acrylamide (192 g), 5 wt % aqueous solution of Trilon™ C (3 g), defoamer (Xiameter™ AFE-0400), 1 wt % aqueous solution of Na-hypophosphite (0.8 g), and 4% ACVA in 5 wt % NaOH solution (3 g) are added and the pH is again adjusted with acetic acid to pH 6.0±0.1.

(89) Next, addition water is added to reach the monomer solids of 30.5% (for calculation ACM, Mg-AA, and unneutralised AA are taken into account). The reaction mixture is cooled down during degassing for 45 minutes. When a temperature of about −1° C. is reached, 4% AIBN solution in methanol (3 g) and 1% aqueous solution of tBHP (0.24 g) are added to the monomer solution and the degassing is continued for 2 minutes.

(90) Next, at a temperature of 0° C.±1.0° C., the polymerization is initiated by adding the 1% aqueous solution of sodium metabisulphite solution (0.48 g). After the polymerization, the wet gel was placed in a heated cabinet at 80° C. for 2 hours. Next, the wet gel is minced, subsequently dried in a fluid bed dryer (55° C. for 2 hours), and finally ground to obtain a white/yellowish powder.

(91) The polymer had the following characteristics: IV: 10.2 dl/g Gel content: 0.3% Visual solubility: good Solid content: 87.2% Residual acrylamide: 565 ppm

Example 10—Treatment of MFT from an Oils ands Mining Operation

(92) The polymers produced in Examples 8 and 9 were tested as flocculants in the treatment and dewatering of a slurry of mature fine tailings (MFT) from an oil sands mining operation. The protocol used was that described above in Example 7.

(93) Table 3 shows the test results obtained for the calcium and magnesium diacrylate polymers (Examples 8 and 9, respectively). The 24 hour NWR data is also represented graphically in FIG. 3.

(94) The results show that the both the magnesium and calcium diacrylate polymers are able to effectively treat, flocculate and dewater the oil sands, MFT slurry.

Example 11—Treatment of Tailings from a Mineral Sands Mining Operation

(95) The polymer prepared in Example 1 was tested as a flocculant in the treatment of a slurry of fine tailings (<53 μm) from a mineral sands mining operation. The tailings sample used had a total solids content of 38% wt/wt.

(96) The following protocol was during the testing.

(97) The polymer was prepared as 0.25% wt/vol solution in process water from the mineral sands mining operation and added to 280 ml of tailings slurry, with mixing via beaker pours to create maximum and optimal flocculation structure (visual assessment). The flocculated material was then placed into a slump collar, which was then removed, allowing the solids to slump and free water to drain from the solids. The amount of slumping was used to estimate the yield stress of the treated solids. The free water released from the treated material was collected and the volume measured after an elapsed time of 5 minutes and used to calculate the net water release, as described in Example 7 above.

(98) The results are shown in Table 4 below.

(99) The results show that the calcium diacrylate polymer of Example 1 is able to effectively treat, flocculate and dewater the mineral sands tailings slurry.

Example 12—Preparation of a 65 w % Ca Diacrylate Polymer (IV=4.5) According to Methodology Described in Examples of Sortwell #2 (CA 2,803,025)

(100) In this example, the reagents and amounts used are shown in Table 5.

(101) The Sortwell example discloses the following about a mixture of these reagents: “A rapid reaction produced a gel. The intrinsic viscosity (IV) of this polymer was 4.5 dl/gm (measured in 1 M NaCl at 25° C.)”. It was noted that the instructions in Sortwell #2 do not include information in respect of how the calcium diacrylate monomer should be prepared, the starting temperature for the reaction and whether deoxygenation was employed prior to initiating the polymerization reaction. Also, Sortwell #2 indicates that the resulting polymer was used to treat oil sands MFT without further processing of the aqueous polymer gel into a dry powder, which would be considered normal and necessary for commercial supply and use of these polymers.

(102) Attempts were made to prepare a similar polymer based on the disclosed details in Sortwell #2. With an expected exotherm of approximately 45° C. from the reaction mixture, we chose a starting temperature of approximately 9° C., as was disclosed for the preparation of the polymer in Example 13 below (as Sortwell #1).

(103) Sample A—0.04% Trilon™ C (chelating agent) addition to the aqueous monomer solution which was then degassed with N.sub.2 for 45 minutes prior to initiation.

(104) Sample B—0.04% Trilon™ C (chelating agent) addition to the aqueous monomer solution which was then degassed with N.sub.2 for 45 minutes prior to initiation. Resultant aqueous gel held at 80° C. for 2 hours after completion of the polymerization process, prior to any further processing.

(105) Samples C, D & E—repeat preparations using the same method as sample A

(106) Following Sortwell #2, the aqueous polymer gel was initially characterized directly and, for a more complete evaluation, we also processed part of each gel through to a dry powder product (as described in Examples 1-6, 8 and 9 above). In all cases, irrespective of whether we used the aqueous gel or dry powder, it was found that the polymer produced was poorly soluble. In general, it required approximately 15 hours to complete the dissolution process and for preparations when it was possible to adequately separate sufficient soluble polymer from the insoluble residue, it was found that the polymers had IV's in the range of 7-10 dl/g, which is substantially higher than the range claimed in Sortwell #2 (i.e., IV of less than 5 dl/gm). It was also found that all the preparations had high levels of residual acrylamide monomer such that of the gels would be classified as being hazardous materials (according to GHS criteria), which would render them unsuitable for general application for industrial water and waste treatment processes (NB: residual monomer values were recorded based upon either the total weight of the aqueous gel or total weight of dry powder, as appropriate). These test results are reported in Table 6.

(107) This example demonstrates that Sortwell #2 provides insufficient information for the preparation of the claimed polymer and/or that the method disclosed is not viable for its production.

Example 13—Preparation of a 65 w % Ca Diacrylate Polymer (IV=18) According to Methodology Described in Examples of Sortwell #1 (CA 2,803,904)

(108) In this example, the reagents and amounts used are shown in Table 7.

(109) The Sortwell example states: “The pH was adjusted to 6.5 with HCl before initiation of the reaction, and the reagents were de-aerated with N.sub.2 and the reaction was initiated at 9° C. and carried to completion, resulting in a linear calcium diacrylate copolymer with an intrinsic viscosity of 18 dl/gm”. It was noted that the instructions in Sortwell #1 provide no information in respect of how the calcium diacrylate monomer should be prepared, duration of the degassing period or the method, and especially the solvent conditions used to measure the IV. Also Sortwell #1 (Example 3) indicates that before the resulting polymer was used to treat the “10% solids clay (predominately sodium clays) slurries in water” the “polymers were dried and ground” by which it was understood that the aqueous gel polymer was further processed into a dry powder, as would be the normal method for the supply of commercially viable polymeric flocculants.

(110) Attempts to prepare a similar polymer based on the disclosed details in Sortwell #1 were undertaken. Each gel was processed through to a dry powder product (as described in Examples 1-6, 8 and 9 above).

(111) Samples F and G—0.04% Trilon™ C (chelating agent) addition to the aqueous monomer solution which was then degassed with N2 for 45 minutes prior to initiation.

(112) Sample H and J—0.04% Trilon™ C (chelating agent) addition to the aqueous monomer solution which was then degassed with N.sub.2 for 45 minutes prior to initiation. Resultant aqueous gel held at 80° C. for 2 hours after completion of the polymerization process, prior to any further processing.

(113) In all cases, it was found that the polymer produced was substantially insoluble, such that it was impossible to measure the IV of the polymer. Attempts were made to dissolve the dry polymer in deionized water, 1% NaCl solution and 1M NaCl solution without success. It was also found that all the preparations had high levels of residual acrylamide monomer such that the products would be classified as being toxic materials (according to GHS criteria), which would render them unsuitable for general application for industrial water and waste treatment processes. As the polymers so produced were all insoluble, it was not possible to elevate the effectiveness of these preparations in the treatment and dewatering of mineral clay, as further described in the examples of Sortwell #1. These test results are reported in Table 8.

(114) This example demonstrates that Sortwell #1 provides insufficient information for the preparation of the claimed polymer and/or that the method disclosed is not viable for its production.

Example 14—20% wt Ca Diacrylate, 20% wt Na Acrylate Polymer (IV=15)

(115) Water (65 g) and glacial acrylic acid (19 g) are added to a reaction vessel. Next, 30 wt % aqueous suspension of Ca(OH).sub.2 (˜34 g) is added to this mixture slowly under cooling and pH control until pH 6.0±0.1 is reached. 35% aqueous solution of sodium acrylate (68.6 g), 51 wt % aqueous solution of Acrylamide (144 g), 5 wt % aqueous solution of Trilon™ C (3.0 g), defoamer (Xiameter™ AFE-0400), 1 wt % aqueous solution of Na-hypophosphite (0.2 g), and 4% ACVA in 5 wt % NaOH solution (3 g) are added and the pH is again adjusted with acetic acid to pH 6.0±0.1.

(116) Next, addition water is added to reach the monomer solids of 30.5% (for calculation ACM, Ca-AA, Na-AA and unneutralised AA are taken into account). The reaction mixture is cooled down during degassing for 45 minutes. When a temperature of about −1° C. is reached, 4% AIBN solution in methanol (3 g), 1% aqueous solution of 2,2-Azobis (2-(2-imidazolin-2-yl)propan) dihydrochlorid (0.4 g) and 1% aqueous solution of tBHP (0.16 g) are added to the monomer solution and the degassing is continued for 2 minutes.

(117) Next, at a temperature of 0° C.±1.0° C., the polymerization is initiated by adding the 1% aqueous solution of sodium metabisulphite solution (0.32 g). After the polymerization, the wet gel was placed in a heated cabinet at 80° C. for 2 hours. Next, the wet gel is minced, subsequently dried in a fluid bed dryer (55° C. for 2 hours), and finally ground to obtain a white/yellowish powder.

(118) The polymer had the following characteristics: IV: 14.5 dl/g Gel content: 0% Visual solubility: good Solid content: 88.1% Residual acrylamide: 200 ppm

Example 15—Treatment of MFT from an Oils ands Mining Operation

(119) The 40% wt anionic polymer produced in Example 14 and a repeat preparation of Example 1 (designated here as Example 1A) were tested as flocculants in the treatment and dewatering of a slurry of mature fine tailings (MFT) from an oil sands mining operation. The protocol used was that described above in Example 7.

(120) Table 9 shows the test results obtained for the 40% wt anionic polymers; calcium diacrylate and the combined sodium/calcium neutralised acrylate (Examples 1A and 14, respectively). The 24 hour NWR data is also represented graphically in FIG. 4.

(121) The results show that the both the polymers prepared by both wholly and partially neutralising the ethylenically unsaturated acid with calcium, are able to effectively treat, flocculate and dewater the oil sands, MFT slurry.

(122) While this invention has been described with reference to illustrative embodiments and examples, the description is not intended to be construed in a limiting sense. Thus, various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments.

(123) All publications, patents and patent applications referred to herein are incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.

(124) TABLE-US-00002 TABLE 1 40 wt % Calcium diacrylate polymers Oil sands MFT Polymer Conditioning Initial Yield 24 hrs NWR 24 hrs Yield treated with: Dose (g/t) Time (Secs) Stress (Pa) (%) Stress (Pa) Example 1 Polymer 1266 19 133 13.9 542 @ 0.5% 1421 66 133 17.2 949 1539 91 131 19.5 1011 1574 140 147 21.7 1105 1635 162 165 21.4 875 1732 215 136 25.5 1261 1815 264 149 21.1 1035 1942 343 112 15.3 633 2043 438 NA 11.7 559 Example 2 Polymer 1020 5 88 16.5 873 @ 0.5% 1172 7 125 22.4 841 1220 6 141 22.1 1257 1278 7 134 23.0 1039 1375 7 124 20.3 781 1525 6 121 17.3 806 Example 3 Polymer 1115 9 116 15.7 423 @ 0.5% 1272 25 143 23.8 930 1369 36 135 23.3 848 1427 54 172 28.8 1260 1528 52 165 27.8 996 1769 112 137 18.2 911 Example 4 Polymer 1355 10 101 13.0 695 @ 0.5% 1445 6 113 12.1 828 1556 4 131 9.3 749 1706 3 125 10.8 1085 1775 3 124 9.4 830 2044 4 89 5.6 731

(125) TABLE-US-00003 TABLE 2 60 wt % Calcium diacrylate polymers Initial 24 hrs Oil Polymer Conditioning Yield 24 hrs Yield sands MFT Dose Time Stress NWR Stress treated with: (g/t) (Secs) (Pa) (%) (Pa) Example 5 1325 16 48 1.6 UR Polymer 1542 6 110 8.0 537 @ 0.5% 1688 8 184 14.0 1219 1775 8 168 14.2 1041 1871 8 187 12.6 870 2037 8 146 12.0 1406 Example 6 1375 8 138 4.1 277 Polymer 1559 11 139 15.0 549 @ 0.5% 1781 18 132 7.6 527 1947 41 163 14.3 943 2037 50 189 12.5 840 2283 101 179 12.4 876

(126) TABLE-US-00004 TABLE 3 Calcium and Magnesium diacrylate polymers Initial 24 hrs Oil Polymer Conditioning Yield 24 hrs Yield sands MFT Dose Time Stress NWR Stress treated with: (g/t) (Secs) (Pa) (%) (Pa) Example 8 1019 12 54.1 6.6 128.0 Polymer 1129 13 68.5 8.7 151.0 @ 0.5% 1320 15 69.4 17.5 307.2 1430 17 64.3 17.9 360.0 1520 18 77.0 21.0 356.8 1735 36 126.9 22.1 744.0 Example 9 1241 12 70.5 19.1 392.0 Polymer 1337 4 78.2 20.6 465.5 @ 0.5% 1441 19 74.0 22.1 444.8 1534 20 72.8 23.5 566.4 1747 41 130.8 24.0 787.2 1845 55 97.7 22.0 760.0

(127) TABLE-US-00005 TABLE 4 Calcium diacrylate polymer Estimated Mineral sands Polymer Yield Stress 5 mins NWR tailings treated with: Dose (g/t) (Pa) (%) Example 1 Polymer 138 54 35 @ 0.25% 173 54 34 208 63 35 234 98 40 260 184 39

(128) TABLE-US-00006 TABLE 5 Reagents Used in Example 12 Reagent Weight % Calcium diacrylate 13.0 Acrylamide 7.0 Demineralized water 79.99 2,2′-Azobis [2-(imidazolin-2-yl)propane] dihydrochloride 0.0018 t-butyl Hydroperoxide 0.0063 Sodium bisulfate 0.0023

(129) TABLE-US-00007 TABLE 6 Product Properties (Example 12) Aqueous Gel Polymer Dry Powder Polymer Sample Solubility ACM (ppm) IV (dl/g) Solubility ACM (ppm) IV (dl/g) A Insoluble 5700 N T Insoluble 8500 NT B Insoluble 1760 NT Insoluble 5500 NT C Very Poor N T 7.6 N T N T N T D Very Poor N T 9.7 N T N T N T E Very Poor N T 6.6 N T N T N T

(130) TABLE-US-00008 TABLE 7 Reagents Used in Example 13 Reagent Weight % Calcium diacrylate 15.6 Acrylamide 8.4 Demineralized water 75.99 Ammonium persulfate 0.0009 Sodium bisulfite 0.0014 2.2:azobis (2-amidinopropane) dihydrochloride 0.0001

(131) TABLE-US-00009 TABLE 8 Product Properties (Example 13) Dry Powder Polymer Sample Solubility ACM (ppm) IV(dl/g) F Insoluble 26,800 NT G Insoluble 40,000 NT H Insoluble 50,400 NT J Insoluble 33,400 NT

(132) TABLE-US-00010 TABLE 9 40% Anionic polymers Initial 24 hrs Oil Polymer Conditioning Yield 24 hrs Yield sands MFT Dose Time Stress NWR Stress treated with: (g/t) (Secs) (Pa) (%) (Pa) Example 1A 1125 16 83 16.3 254 Polymer 1232 13 0 17.9 611 @ 0.5% 1338 17 92 19.5 584 1433 22 96 20.4 934 1525 88 91 23.3 1032 1636 97 108 22.2 1059 Example 14 1130 13 98 16.9 565 Polymer 1233 21 80 19.5 872 @ 0.5% 1330 63 92 20.9 830 1434 120 95 22.0 998 1532 223 110 21.9 1144 1649 282 127 22.6 1157