Dewatering method and system
The present invention relates to methods for dewatering tailings and systems for performing same. In certain aspects, the invention relates to methods of producing a dewatered tailings residue or a stackable tailings residue, comprising subjecting tailings to hydrocyclonic separation to produce one or more partially dewatered underflows and a final water-rich overflow; separating the final water-rich overflow, by centrifuging, into a recovered water stream and a low-water residue; and mixing together the low-water residue and at least part of the one or more partially dewatered underflows to produce a dewatered tailings residue or a stackable tailings residue.
1 . A method of producing a dewatered tailings residue, comprising:
feeding tailings comprising a waste material that is the end result of a consecutive processing system in a mining operation, to a hydrocyclone at a feed inlet pressure ranging from 0.5 MPa to 1.5 MPa,
subjecting the tailings to hydrocyclonic separation to produce one or more partially dewatered underflows and a final water-rich overflow;
separating the final water-rich overflow, by centrifuging, into a recovered water stream and a low-water residue wherein at least 96% of the solids contained in the final water-rich overflow are recovered in the low-water residue; and
mixing together the low-water residue and at least part of the one or more partially dewatered underflows to produce the dewatered tailings residue, wherein the dewatered tailings residue has a solid content of 75 wt % to 90 wt %.
2 . The method according to claim 1 , wherein:
the tailings are subjected to a plurality of hydrocyclonic separation stages, including a first stage and a final stage;
each hydrocyclonic separation stage is configured to separate an input into one of the one or more partially dewatered underflows and the water-rich overflow;
the input of the first stage comprising the tailings;
the water-rich overflow of each stage preceding the final stage being an input to a next adjacent stage; and
the final water-rich overflow is the water-rich overflow of the final stage.
3 . The method according to claim 2 , wherein at least some of the one or more partially dewatered underflows of one of the plurality of hydrocyclonic separation stages is collected as a highly dewatered product.
4 . The method according to claim 3 , wherein the stage from which the highly dewatered product is collected is the first stage of hydrocyclonic separation.
5 . The method according to claim 1 , wherein the dewatered tailings residue has a solids content of about 80 wt %.
6 . The method of producing a dewatered tailings residue according to claim 5 , further comprising pumping the dewatered tailings residue to a disposal site.
7 . The method according to claim 1 , further comprising:
injecting gas into the tailings, before the tailings are fed to the hydrocyclone, at a pressure higher than the feed inlet pressure.
8 . The method according to claim 7 , wherein injecting gas comprises injecting up to 60 m 3 /hr of gas into the tailings.
9 . The method according to claim 7 , wherein the gas is air.
10 . The method according to claim 1 , wherein the dewatered tailings residue contains a final solid content of greater than 85 wt %.
11 . The method according to claim 1 , wherein the low-water residue has a solids content of at least 60 wt %.
12 . The method according to claim 1 , wherein the recovered water stream has a solids content of 1 wt % or less.
13 . The method according to claim 1 , wherein the recovered water stream is directly reused in the consecutive processing system in a mining operation which produced the tailings.
14 . The method according to claim 1 , wherein the amount of solids contained in the final water-rich overflow is less than 50% of the total solids from the tailings.