We Claim:
1. A method for re-dispersing dewatered, partially dried or essentially dried
microfibrillated cellulose, the method comprising the steps of:
(a) adding a quantity of a suitable dispersing liquid to a tank having at least one
inlet and an outlet, wherein the tank further comprises a mixer and a pump
attached to the outlet;
(b) adding a quantity of dewatered, partially dried or essentially dried microfibrillated cellulose to the tank through the at least one inlet in sufficiënt quantity to yield a liquid composition of microfibrillated cellulose at a desired solids concentration;
(c) mixing the dispersing liquid and the dewatered, partially dried or essentially dried microfibrillated cellulose in the tank with the mixer to partially de-agglomerate and re-disperse the microfibrillated cellulose to form a flowable slurry;
(d) pumping the flowable slurry with the pump to an inlet of a flow cell, wherein the flow cell comprises one or more sonication probe in series and at least one outlet;
(e) applying ultrasonic energy to the slurry of at least 200 kWh/t continuously by the sonication probe at a frequency range of 19 to 100 kHz;
(f) collecting the re-dispersed suspension comprising microfibrillated cellulose
with enhanced tensile strength and/or viscosity properties from the at least one
outlet of the flow cell in a suitable holding vessel.
2. The method of claim 1, wherein a second outlet of the flow cell is connected to a second inlet of the tank, thereby providing for a continuous recirculation loop providing for the continuous application of ultrasonic energy to the slurry for a desired time period and/or total energy input range.
3. The method of claim 1 or 2, wherein the dewatered, partially dried or essentially dried microfibrillated cellulose composition further comprises at least one inorganic particulate material.
4. The method of claim 1 or 2, wherein the dispersing liquid is water.
5. The method of claim 3, wherein the dispersing liquid is water.

6. The method of claim 1 or 2, wherein the ultrasonic energy input is from about 1,000 kWh/t to about 10,000 kWh/t.
7. The method of claim 3, wherein the ultrasonic energy input is from about 1,000 kWh/t to about 10,000 kWh/t.
8. The method of claim 7, wherein the ultrasonic energy input is from about 1,000 kWh/t to about 2,000 kWh/t.
9. The method of claim 1 or 2, wherein the ultrasonic energy input is from about 1,000 kWh/t to about 2,000 kWh/t.
10. The method of claim 1 or 2, wherein the ultrasonic energy input is from about 200 kWh/t to about 400 kWh/t.
11. The method of claim 3, wherein the ultrasonic energy input is from about 200 kWh/t to about 400 kWh/t.
12. The method of claims 1 or 2, wherein the flow cell has a cooling jacket for maintaining a temperature of the suspension of microfibrillated cellulose in the range of about 1°Cto about 80° C.
13. The method of claim 12, wherein the flow cell has a cooling jacket for maintaining a temperature of the suspension of microfibrillated cellulose in the range of about 20° C to about 50° C.
14. The method of claim 3, wherein the flow cell has a cooling jacket for maintaining a temperature of the suspension of microfibrillated cellulose in the range of about 1°Cto about 80° C.
15. The method of claim 14, wherein the flow cell has a cooling jacket for maintaining a temperature of the suspension of microfibrillated cellulose in the range of about 20° C to about 50° C.
16. The method of claim 13, wherein the temperature is room temperature.
17. The method of claim 15, wherein the temperature is room temperature.
18. The method of claim 13, wherein the temperature is 20° C.
19. The method of claim 15, wherein the temperature is 20° C.

20. The method of claim 1 or 2, wherein the flow cell comprises an adjustable valve at the second outlet to create back pressure of the recirculated liquid of from about 0 to about 10 bar.
21. The method of claim 20, wherein the flow cell comprises an adjustable valve at the second outlet to create back pressure of the recirculated liquid of from about 0 to about 4 bar.
22. The method of claim 21, wherein the pressure is 3 bar.
23. The method of claim 3, wherein the flow cell comprises an adjustable valve at the second outlet to create back pressure of the recirculated liquid of from about 0 to about 10 bar.
24. The method of claim 23, wherein the flow cell comprises an adjustable valve at the second outlet to create back pressure of the recirculated liquid of from about 0 to about 4 bar.
25. The method of claim 24, wherein the pressure is 3 bar.
26. The method of claim 1 or 2, wherein the flow cell further comprises one or more boosters to mechanically increase or decrease the amplitude of the at least one sonication probe.
27. The method of claim 3, wherein the flow cell further comprises one or more boosters to mechanically increase or decrease the amplitude of the at least one sonication probe.
28. The method of claim 1 or 2, wherein the liquid composition of microfibrillated cellulose is at least 0.5 to 5% fibre solids.
29. The method of claim 28, wherein the liquid composition of microfibrillated cellulose is about 0.5% to about 1%.
30. The method of claim 28, wherein the liquid composition of microfibrillated cellulose is about 1.5% fibre solids.
31. The method of claim 28, wherein the liquid composition of microfibrillated cellulose is about 1.8% fibre solids.
32. The method of claim 28, wherein the liquid composition of microfibrillated cellulose is about 2.5% fibre solids.

33. The method of claim 3, wherein the liquid composition of microfibrillated cellulose is at least 0.5 to 5% fibre solids.
34. The method of claim 33, wherein the liquid composition of microfibrillated cellulose is about 0.5% to about 1%.
35. The method of claim 33, wherein the liquid composition of microfibrillated cellulose is about 1.5% fibre solids.
36. The method of claim 33, wherein the liquid composition of microfibrillated cellulose is about 1.8% fibre solids.
37. The method of claim 33, wherein the liquid composition of microfibrillated cellulose is about 2.5% fibre solids.
38. The method of claim 1 or 2, wherein the microfibrillated cellulose is pelletized.
39. The method of claim 3 wherein the microfibrillated cellulose composition comprising inorganic particulate material is pelletized.
40. The method of claims 1 or 2, wherein the ultrasonic energy is applied for about 1 to about 120 minutes.
41. The method of claim 40, wherein the ultrasonic energy is applied for about 30 minutes.
42. The method of claim 3, wherein the ultrasonic energy is applied for about 1 to about 120 minutes.
43. The method of claim 42, wherein the ultrasonic energy is applied for about 30 minutes.
44. The method of claim 1 or 2, wherein the ultrasonic energy is applied until a specified ultrasonic energy input is achieved greater than 200 kWh/t.
45 The method of claim 3, wherein the ultrasonic energy is applied until a specified ultrasonic energy input is achieved greater than 200 kWh/t.
46. The method of claim 1 or 2, wherein the ultrasonic energy is applied until a specified cumulative ultrasonic energy input greater than 400 kWh/t is achieved.

47. The method of claim 3, wherein the ultrasonic energy is applied until a specified cumulative energy input is achieved.
48. The method of claim 1 or 2, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 500 kWh/t is achieved.
49. The method of claim 3, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 500 kWh/t is achieved.
50. The method of claim 1 or 2, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 1,000 kWh/t is achieved.
51. The method of claim 3, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 1,000 kWh/t is achieved.
52. The method of claim 1 or 2, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 1,500 kWh/t is achieved.
53. The method of claim 3, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 1,500 kWh/t is achieved.
54. The method of claim 1 or 2, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 2,000 kWh/t is achieved.
55. The method of claim 3, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 2,000 kWh/t is achieved.
56. The method of claim 1 or 2, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 2,500 kWh/t is achieved.
57. The method of claim 3, wherein the ultrasonic energy is applied until a cumulative ultrasonic energy input of 2,500 kWh/t is achieved.
58. The method of claim 1 or 2, wherein the recirculation loop further comprises a high shear mixer.
59. The method of claim 3, wherein the recirculation loop further comprises a high shear mixer.
60. The method of claim 1 or 2, wherein the suspension of microfibrillated cellulose has an FLT index of 7.5 Nm/g or more.

61. The method of claim 1 or 2, wherein the suspension of microfibrillated cellulose has an FLT index of 8.0 Nm/g or more.
62. The method of claim 1 or 2, wherein the suspension of microfibrillated cellulose has an FLT index of 8.5 Nm/g or more.
63. The method of claim 1 or 2, wherein the suspension of microfibrillated cellulose has an FLT index of 10 Nm/g or more.
64. The method of claim 3, wherein the suspension of microfibrillated cellulose has an FLT index of 7.5 Nm/g or more.
65. The method of claim 3, wherein the suspension of microfibrillated cellulose has an FLT index of 8.0 Nm/g or more.
66. The method of claim 3, wherein the suspension of microfibrillated cellulose has an FLT index of 8.5 Nm/g or more.
67. The method of claim 2, wherein the liquid composition comprising microfibrillation cellulose is recirculated for about 30 to about 120 minutes.
68. The method of claim 67, wherein the liquid composition comprising microfibrillation cellulose is recirculated for about 30 minutes.
69. The method of claim 3, wherein the liquid composition comprising microfibrillation cellulose is recirculated for about 30 to about 120 minutes.
70. The method of claim 69, wherein the liquid composition comprising microfibrillation cellulose is recirculated for about 30 minutes.
71. A re-dispersed microfibrillated cellulose suspension produced by the process of claim 1 or 2.
72. A re-dispersed microfibrillated cellulose suspension produced by the process of claim 3.
73. The method of claim 1 or 2, wherein sonication is run in pulse mode.
74. The method of claim 3, wherein sonication is run in pulse mode.
75. The method of claim 1 or 2, wherein said partially dry product is formed into a belt-pressed cake prior to sonication.

76. The method of claim 3, wherein said partially dry product is formed into a belt-pressed cake prior to sonication.
77. The method of claim 1 or 2, wherein the FLT index of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 5% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
78. The method of claim 1 or 2, wherein the FLT index of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 10% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
79. The method of claim 1 or 2, wherein the FLT index of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 20% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
80. The method of claim 3, wherein FLT index of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 5% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
81. The method of claim 3, wherein the FLT index of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 10% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
82. The method of claim 3, wherein the FLT index of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 20% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.

83. The method of claim 1 or 2, wherein said viscosity of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 5% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
84. The method of claim 1 or 2, wherein said viscosity of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 10% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
85. The method of claim 1 or 2, wherein said viscosity of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 20% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
86. The method of claim 3, wherein said viscosity of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 5% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
87. The method of claim 3, wherein said viscosity of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 10% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
88. The method of claim 3, wherein said viscosity of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties is increased by at least 20% over the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material not subject to sonication.
89. The method of claim 1 or 2, wherein the microfibrillated cellulose may be prepared from chemical pulp, or a chemithermomechanical pulp, or a mechanical pulp,

or a recycled pulp, or a paper broke pulp, or a papermill waste stream, or waste from a papermill, or combinations thereof.
90. The method of claim 3, wherein the inorganic particulate material is an alkaline earth metal carbonate or sulphate, such as calcium carbonate, magnesium carbonate, dolomite, gypsum, a hydrous kandite clay such as kaolin, halloysite or ball clay, an anhydrous (calcined) kandite clay such as metakaolin orfully calcined kaolin, talc, mica, perlite or diatomaceous earth, or combinations thereof.
91. The method of claim 3, wherein the microfibrillated cellulose may be prepared from a chemical pulp, or a chemithermomechanical pulp, or a mechanical pulp, or a recycled pulp, or a paper broke pulp, or a papermill waste stream, or waste from a papermill, or combinations thereof.
92. The method of claim 3, wherein the inorganic particulate material is an alkaline earth metal carbonate, for example, calcium carbonate.
93. The method of claim 3, wherein the inorganic particulate material is kaolin.
94. The method of claim 1 or 2, wherein the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties obtained by the method is suitable for use in a method of making paper or coating paper, paints and coatings, inks, oilfield chemicals, composites, consumer products, cosmetic products, pharmacological products and food products.
95. The method of claim 3, wherein the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material with enhanced viscosity and tensile strength properties obtained by the method is suitable for use in a method of making paper or coating paper, paints and coatings, inks, oilfield chemicals, composites, consumer products, cosmetic products, pharmacological products and food products.
96. The method of claim 1 or 2, wherein said method further comprises one or more of high shear mixing, homogenization and refining either before or after the sonication step.