Method and device for shear-thinning of solids containing material
This invention relates to a method and device to be used in connection with thickening and clarifying apparatuses for shear-thinning of solids containing material such as slurry. According to the invention the flow area of the shear-thinned material ( 11 ) is restricted by arranging a restriction element ( 12 ) in the conduit ( 4,15 ) for discharging back the shear-thinned material ( 11 ).
1. Apparatus for producing shear-thinned slurry, comprising:
a thickening apparatus having a wall,
a shear-thinning apparatus,
at least one first conduit for feeding slurry to be shear-thinned from the thickening apparatus to the shear-thinning apparatus, said first conduit having an end connected to the wall of the thickening apparatus,
at least one second conduit for returning the shear-thinned slurry from the shear-thinning apparatus to the thickening apparatus, said second conduit having an end connected to the wall of the thickening apparatus, and
at least one discharge line connected to the second conduit;
wherein the first conduit and the second conduit are positioned essentially concentrically to each other at least in the ends connected to the thickening apparatus, said conduits forming openings in the wall of the thickening apparatus,
and wherein the apparatus further comprises a controllable restriction element arranged in the second conduit and located downstream of the discharge line, wherein said restriction element restricts the flow area of the shear-thinned slurry and increases shear-thinning of the slurry.
2. Apparatus according to claim 1 , wherein the second conduit has an end portion of a larger external dimension than the first conduit and concentrically surrounds an end portion of the first conduit and the restriction element is arranged in the second conduit upstream of said end portion thereof.
3. Apparatus according to claim 1 , wherein the second conduit has an end portion of a smaller external dimension than the first conduit and concentrically surrounded by an end portion of the first conduit and the restriction element is arranged in the second conduit upstream of said end portion thereof.
4. Apparatus according to claim 1 , wherein the restriction element is a controllable valve.
5. Apparatus for producing shear-thinned slurry, comprising:
a thickening apparatus having a wall,
a shear-thinning apparatus,
at least one first conduit for feeding slurry to be shear-thinned from the thickening apparatus to the shear-thinning apparatus, said first conduit having an end connected to the wall of the thickening apparatus, and
at least one second conduit for discharging back the shear-thinned slurry from the shear-thinning apparatus to the thickening apparatus, said second conduit having an end connected to the wall of the thickening apparatus,
wherein the first conduit and the second conduit are positioned essentially concentrically to each other at least in the ends connected to the thickening apparatus, said conduits forming openings in the wall of the thickening apparatus,
and wherein the apparatus further comprises a restriction element arranged in the second conduit, wherein said restriction element restricts the flow area of the shear-thinned slurry and increases shear-thinning of the slurry, and
wherein the restriction element is an orifice plate.
6. Apparatus according to claim 1 , further comprising a discharge line arranged between the shear-thinning apparatus and the restriction element for discharging a part of the shear-thinned slurry.