CA2910470A1 - Method and device for management and treatment of fluid tailings in tailings pond - Google Patents

Abstract

This invention discloses a method and relevant devices for management and treatment of fluid tailings, and in-situ deposition of the treated tailings within a tailings pond, as well as simultaneous reclamation of the tailings pond. The method of the invention comprises: a) using a floating dyke to divide a tailings pond into two sections, b) using one of the sections to collect the runoff fluid tailings, c) using a floating divider and combining with the other side of the floating dyke to form a bottomless thickener for treatment of fluid tailings, in-situ deposition of the treated tailings, and building up an under-water beach from the treated tailing deposits, and d) relocating the floating dyke and the floating divider downstream to build up a new dividing and treatment system after the under-water-beach meets the reclamation requirements, and developing a new above-water-beach to cover the under-water-beach for tailings pond reclamation. The invention also provides relevant devices for using the said method.

Description

METHOD AND DEVICE FOR MANAGEMENT AND TREATMENT
OF FLUID TAILINGS IN TAILINGS POND
TECHNICAL FIELD
The technical field relates to management and treatment of fluid tailings in tailings pond, and speeding up reclamation of tailings pond.
BACKGROUND
Fluid tailings are generated from various mine-processing operations that extract the valuable components from the mined ore and leave various solid-water slurry wastes as tailings in tailings management facilities (TMF), known as tailings ponds. Over the years the volume of tailings has grown dramatically as the demand for metals, minerals, and fossil fuels has increased. In recent years, more lower grade ores are being mined using advanced processing technologies to increase the recovery of valuable fractions from the ore, resulting in more fluid tailings in tailings pond. It was estimated that in 2000 there were about 3500 active tailings ponds in the world (T E Martin, M
P Davies, (2000), hup://www.infomine.com/publications/docs/Martin2000), and the amount of fluid tailings generated by an individual mine was about 100,000 tones per day (A
Jakubick, G McKenna, et al. (2003), Stabilization of Tailings Deposits: International Experience, Mining and the Environment III, Sudbury, Ontario, Canada, May 25-28, 2003. pp. 1-9.). A new estimate in 2012 predicted the amount of fluid tailings generated by an individual mine in excess of 200,000 tones in a single day (J Engels, (2014), http://www.tailings.info/about.htm). The oil sands industry in Northern Alberta, Canada is one of the examples that generate and hold a huge amount of fluid tailings in its tailings ponds. The oil sands mining operation started in late 1960s, the bitumen in oil sands ore is extracted through hot water extraction process. The extraction process requires about 0.6 to 0.7 cubic meters of water to process per ton of oil sands ore, and the demand of fresh make-up water for the extraction process is in the range of 3 to 4 cubic meters per cubic meter of bitumen

2 produced, although most of the process water is recycled. It was estimated that by 2012 the existing tailings ponds water covered about a 77 square kilometer area (Government of Alberta, (2013), Fact Sheets Tailings, http://www.oilsands.alberta.ca/FactSheets/Tailings_FSht Sep 2013Online), and contained over 720 million cubic meters of fluid tailings (Pembina, (2010), Backgrounder: Oil Sands Tailings and Directive 074, https://www.pembina.org/reports/tailings-directive-074-backgrounder).
Conventionally, fluid tailings are stored in various surface impoundments using natural landscapes, dams and dykes to confine the fluid tailings in tailings ponds for years with or without further treatment, and the mine operators are always to seek the most cost-effective ways possible to meet regulations and mine site specific factors. In recent years, some new technologies have been employed to improve water release from fluid tailings, such as in plant thickening, centrifuging, and filtration, that make the fluid tailings into paste or cake-like tailings for direct landfills or backfills with or without further drying treatment, however, the handling and transportation of the paste and cake-like tailings are difficult, and the costs for the treatment and handling of high solids content tailings are much higher than the ponding process. In addition to the technical and economical concerns, the challenges for design of fluid tailings management facilities grow from regulatory bodies, governments, and publics, focusing on safety, environmental protection, ecological balance, and sustainable development. The challenges are forcing the mine operators to find more innovative ways to solve the issues on fluid tailings management and realize cost-savings in their operations.
The objective of the present invention is to provide mining operators with methods and devices at a much low cost to realize: a) a revolutionary conversion of tailings ponds from single-function tailings storage facilities into multi-function tailings and water handling, treatment, and management facilities, b) simultaneous reclamation of tailings ponds during the mining operations, and c) complete the reclamation right after the mine closure.
SUMMARY OF THE INVENTION
This invention discloses a method and relevant devices for handling and treatment of fluid tailings in tailings pond, and in-situ deposition of the treated tailings, so as to speed up the reclamation of the tailings pond.

3 In some embodiments, there is a method to achieve easy handling and treatment of fluid tailings in tailings pond, deposition of the treated tailings in-situ, and complete reclamation of the tailings pond during the handling, treatment, and deposition of the fluid tailings. The said method comprises multi-steps, including: a) using a floating dyke to separate a tailings pond into two sections, b) using one of the sections as runoff collection pond to collect the runoff fluid tailings that are overflow from the above-water-beach area, and developing an under-water-beach within the runoff collection pond, c) using a floating divider and combining with the floating dyke to form a bottomless thickener along the deeper side of the floating dyke, d) flocculating various fluid tailings that are derived from the processing plant and/or from the runoff collection pond through a flocculation station, e) thickening and depositing the flocculated tailings within the bottomless thickener, f) recovering water from the top of the bottomless thickener, and developing an under-water-beach by the thickened tailings deposits at the tailings pond bottom below the bottomless thickener, g) relocating the bottomless thickener along the floating dyke, and repeating the steps c to f to continue the development of the under-water-beach along the deeper side of the floating dyke until the depth of deposits meets the reclamation requirements, h) setting up a dividing and treatment system by relocating the floating dyke and the floating bottomless thickener downstream in the tailings pond, and developing the above-water-beach to cover the under-water-beach formed in previous steps a to g for tailings pond reclamation, and i) repeating steps a to h until the completion of the tailings pond reclamation.
In some embodiments, the said method can be used for handling and treatment of all types of fluid tailings that are generated from various mine processing plants and tailings storage facilities, such as coarse sand tailings, flotation tailings, mature fine tailings, fluid fine tailings, off-spec recycle water, and the combinations of the above-mentioned tailings. The said method can also be used for reclamation of all types of tailings ponds that are used to manage and store various fluid tailings, such as in-pit tailings pond, out-of-pit tailings pond, new tailings pond without old fluid tailings in it, existing active tailings pond with old fluid tailings in it, and existing inactive tailing pond with old fluid tailings in it, but without fresh tailings input into it.
In some embodiments, the said floating dykes and floating dividers are major devices for management, handling, and treatment of fluid tailings in tailings pond. The floating dykes and floating dividers are similar in structure and materials, both the floating dykes and floating dividers

4 include two major parts: a) the floating device at the top of water surface, and b) the dividing sheet with its top attached to the floating device and its bottom falling down close to the bottom of the tailings pond. The floating dykes have more floating devices on the water surface for various functions, including: a) walkways for operation and maintenance, b) working platforms for specific operations, such as flocculation stations, pump stations, utilities and materials supply and storage, c) pipe rack and pipeline supports, and d) connections for positioning and locating various operation devices, such as guiding cables, poles, pillars, lockers, and other devices for water surface positioning. The major function of floating dykes and floating dividers are to provide isolation media to form various closed cells within the tailings pond. The closed cells can be used for water holding, fluid tailings holding, fresh incoming tailings holding, and treated tailings holding.
Although the bottom of the dividing sheet is designed to touch the bottom of the tailings pond to form completely closed cells, however, in some situations, the lowest edge of the dividing sheet is designed not to touch the bottom of the tailings pond, that is, there is a gap between the bottom of the closed cells and the bottom of the tailings pond. The size of the closed part of the cells along the depth of the floating devices is carefully designed in most operation cases to meet the requirements for the isolation or treatment. The design of bottomless closed cells is used for fluid tailings handling and transportation through the bottom connection, and for the top water handling and transportation through the top connection. The design of bottomless closed cells can also be used for: a) thickening of the fluid tailings at the closed section of the cells, b) in-situ depositing the thickened tailings down to the bottom of the tailings pond just below the thickening area, and c) building up the under-water-beach with the thickened tailings deposits. The thickening also includes the clarification process for a low solids content stream.
In some embodiments, the size and shape of the floating dykes and floating dividers are adjustable to meet the requirements of different operations, including: a) complete isolation of fluid materials in tailings pond, b) partial isolation of fluid materials in tailings pond, c) gradual change of the gap between the bottom of the dividing sheet and the bottom of the tailings pond for the development of under-water-beach, d) various shapes of the closed cells to fit the space available, and e) various zoned shapes to match the requirements of rotating treatment operations. In some embodiments, any combinations between floating dykes and/or floating dividers can be used to form closed cells in different sizes and shapes in the tailings pond, and the sizes and shapes are flexible and adjustable.

In some embodiments, the sizes and shapes of the dividing sheets of the floating dykes and floating dividers are also flexible and adjustable along the depth of the closed cells.
In some embodiments, the gap between the bottom of the dividing sheet and the bottom of tailings pond is changed accordingly in terms of the elevation change of water surface.
The elevation may increase due to the increase of fluid volume in tailings pond, resulting from planned dam elevation increase, followed by the fluid volume increase. The elevation may decrease due to the decrease of fluid volume in tailings ponds, resulting from planned withdraw of water or fluid tailing out of the tailings pond.
In some embodiments, the floating devices of the floating dykes and floating dividers are commercially available devices, including: a) floating docks, b) floating platforms, c) floating working structures, d) chained barges or boats, e) chained pipe bundles, and f) chained drum bundles.
In some embodiments, the floating devices of the floating dykes and floating dividers can be mobile devices that are used to hang the dividing sheets above the water surface at required locations. The supporting devices include: a) suspending cable systems, b) above water working platforms, c) above water walkways or access roads, d) mobile pillars and poles hanging systems, and e) any combinations of a to d.
In some embodiments, the floating devices of the floating dykes and the floating dividers can be any combinations of the floating devices and the mobile supporting devices that are listed above.
In some embodiments, the materials for the dividing sheets of the floating dykes and the floating dividers include: a) woven or non-woven geotextile, b) woven or non-woven cloth, c) non-permeable and semi-permeable polymer membrane or thin film, including plastics, rubber, and composite materials, d) water permeable networks, including metal and non-metal meshes, nets, webs, and filter media, and e) any combinations of a and d.
In some embodiments, the materials for the dividing sheets of the floating dykes and the floating dividers are thermal insulations that are used in cold seasons to avoid heat loss or water surface freezing. The thermal insulation materials include: a) thin polymer foams, b) thin polymer fiber layers, c) thin polymer coatings, and d) any combinations of a to c.
In some embodiments, the dividing sheets can be made from a single piece of materials that are listed above into large piece by the following means: a) zippers, b) adhesives, c) sewing, d) Velcro strips or patches, and e) any combinations of a to d.
In some embodiments, the structure of a bottomless thickener has a simple configuration, including:
a) a peripheral border to define the settling area of the thickening operation and control the depth of the thickened tailings deposits, b) one or more feedwells with distributors at the outlets of the feedwells to improve the dewatering of thickened tailings evenly across the settling area, c) a skimming mechanism to collect the free bitumen or free floats at the top of water surface, and free bitumen and floats collection well, and d) a water transport well for water recovery from the bottomless thickener. In some embodiments, the bottomless thickener can be further simplified to have: a) a peripheral border to define the settling area and the depth of the thickener, and b) a feed pipe with a distributor at the outlet of the pipe.
In some embodiments, the peripheral border of the bottomless thickener can be form by: a) a floating dyke, b) a floating divider, c) a combination of a floating dyke and a floating divider, and d) other floating devices with dividing sheet hanging below the floating devices.
The shape of the bottomless thickener can be: a) circles, b) squares, c) rectangles, d) triangles, and e) any combinations of a to d. The preferred shape is rectangular.
In some embodiments, the size of the bottomless thickener is flexible, depending on the treatment required. The size is in a range of 100 m2 to 100000 m2, and the preferred size is in the range of 5000 m2 to 10000 m2.
In some embodiments, the size and shape of the bottomless thickener are adjustable through the change in connections and positioning of various floating devices. As mentioned before, in most cases, the floating dykes and/or the floating dividers form the bottomless thickener, so the height of the sidewall has been pre-determined. The depth for thickening and depositing operations is in a range of 5 m to 65 na, the preferred depth is in the range of 8 m to 35 m. The height of the sidewall of the bottomless thickener can be adjusted within the range of 5 in to 35 m in terms of the progress of the thickening and deposition operations.
In some embodiments, there is a method to enhance the dewatering and strengthening of thickened tailings deposits during the thickening and deposition operations within the bottomless thickener.
The method comprises: a) splitting the bottomless thickener into two zones, b) starting from zone 1 with flocculation, thickening, and deposition of fluid tailings to build up 2 m to 3 in thickened tailings deposits, c) moving to zone 2 to continue the flocculation, thickening, and deposition of fluid tailings to build the same depth of deposits, at the same time in zone 1, using coarse tailings to do flocculation, thickening, and deposition to build up 0.5 in to 1 m thickened coarse tailings deposits as sand-cap on top of the thickened fine tailings deposits, d) repeating the operation in the sequence to build up the deposits layers until the total depth of the deposits reaches the operation limit, and e) relocating the thickener to another location. The depth of the deposits is in a range of 15 to 45 m, the preferred depth of deposits is in the range of 8 m to 35 m.
In some embodiments, the bottomless thickener can be split into multi-zones by the floating dividers, the number of zones depends on the minimum settling area required, the actual settling area in each zone should be one to ten times of the minimum settling area. The preferred zone area is in the range of two to five times of the minimum settling area. The bottomless thickener can be split into multi-zones by adding a group of floating dividers.
In some embodiments, there is a method to further enhance the dewatering and strengthening of the thickened tailings deposits. In this method, the floating dividers work parallel to form a series of narrow gaps between each thickening zone, the thickening and deposition operations within the thickening zones are the same as previously mentioned, while the gaps between the floating dividers are used to deposit the coarse tailings with or without flocculation. The coarse tailings deposits form a series of coarse sand walls between each thickening zone. This operation forms a sand network within the deposits, and the sand network enhances the dewatering and strengthening process of the thickened fine tailings. The distance between two nearest sand walls is in a range of 5 in to 50 in, the preferred distance is in the range of 10 in to 35 The thickness of each vertical sand wall is in a range of 0.5 to 5 in, the preferred thickness is in the range of 1 m to 2 in.
The floating dividers can be relocated after the operation, however, the whole dividing sheets or a part of the dividing sheets can be left in place as reinforcement structure after the operation.
In some embodiments, the bottomless thickener can be split into multiple thickening zones, the thickening and deposition operations can be done the same as mentioned before, while a group of thin columns that are formed from the floating dividers are placed evenly into the bottomless thickener. When the thickening and deposition operation continue in the thickening zones, the coarse tailings are deposited into the columns with or without flocculation.
When the thickening and deposition operations are completed, a coarse sand network is formed within the deposits, and the sand network enhances the dewatering and strengthening of thickened fine tailings. The interval of sand columns is in a range of 5 m to 50 m, the preferred interval is in the range of 10 in to 30 m. The shape of the sand columns can be circle, square, rectangle, and triangle, or irregular shapes. The cross-sectional area of the sand columns can be in a range of 1 m2 to 10 m2, the preferred cross-sectional area is in the range of 2 m2 to 4 n-12. The dividing sheets can be removed from the deposits after the operation for reuse.
In some embodiments, there is a method for handling and treatment of fluid tailings in an existing active tailings pond that has old fluid tailings in it and accepts new fluid tailings from processing plant at the same time. Although the method for handling and treatment of new fluid tailings reporting to the existing active tailings pond is the same as mentioned before, extra steps are needed to deal with the old fluid tailings in order to set up a fluid tailings treatment and deposition system in the tailings pond. Furthermore, the old fluid tailings in this type of tailings pond can be treated in different ways that will be described below.
In some embodiments, in addition to the steps for fresh tailings treatment and deposition, there are extra steps needed to set up the bottomless thickener for quickly starting up the thickening operation in the existing tailings pond. The extra steps comprise: a) using a floating divider to set up a closed cell next to the floating dyke, b) withdrawing the top water from the tailings pond and feeding the water into the closed cell from the top until the water level is higher than the top water level of the tailings pond and reaches constant, c) converting the closed water holding cell to a thickening cell by discharging the flocculated tailings into the closed water holding cell, and d) starting normal thickening and deposition operations as mentioned for the new tailings pond.

I some embodiments, there is a method for handling and treatment of fluid tailings in an existing inactive tailings pond that has old fluid tailings in it. The method for handling and treatment of fluid tailings in an existing inactive tailings pond comprises: a) using two floating dividers to set up two closed cells linked together, b) leaving the bottom of the two closed cell open and connected to the existing fluid tailings, c) choosing one cell for water holding, and the other one for fluid tailings holding, d) withdrawing top water from fluid tailings holding cell to the water holding cell until the top water layer disappears in the fluid tailings holding cell, e) withdrawing top water from the tailings pond and feeding into the water holding cell until the water level is higher than the top water level of the tailings pond and becomes constant, f) taking the fluid tailings in the fluid tailings holding cell to do the flocculation treatment, and depositing the flocculated tailings into the water holding cell for thickening and dewatering, g) discharging water from the water holding cell to tailings pond through overflow, and depositing the thickened tailings to the bottom of the tailings pond below the water holding cell, h) relocating the water holding cell after the deposits reach the upper limit of the operation, i) repeating steps a to h until the completion of the fluid tailings treatment in the whole tailings pond, and j) starting tailings pond reclamation during or after step i through reducing top water volume, sand-capping the thickened tailings deposits, and landfilling with solid materials along the shoreline of the tailings pond.
In some embodiments, there is a method for handling and treatment of fluid tailings in an existing active or inactive tailings pond in terms of seasonal conditions. In warm regions where no freezing happens year-round, and/or in wat in seasons when freezing does not happen, the fluid tailings can be flocculated and thickened in the water holding cell and deposited within the tailings pond below the water holding cell, or flocculated and deposited in the beach area close to the shoreline below or above water surface. In cold region and/or in freezing seasons, the fluid tailings can be treated through freezing-thawing cycles year-by-year by spreading the fluid tailings on top of the deposits that were deposited during the warm seasons, or on the ice surface close to the shoreline. The ice layer will be thawed in the coming year, and the thawed tailings will form a new tailings deposition layer on the top. The process cycle can be repeated to add more flocculated tailings on top of the thawed tailings layer during the warm seasons, and add more freezing tailings on top of the flocculated tailings layer during the freezing seasons until the fluid tailings in the tailings pond are treated completely, and further operations for tailings pond reclamation can follow.

In some embodiments, the handling and treatment of fluid tailings in an existing active and/of inactive tailings pond can be done in a periodical manner. The rotating period of time can be a month, three months, six months, and 12 months, or in terms of seasonal weather conditions.
Particularly in warm region, the flocculation, thickening, and deposition can be done in a whole year without a operation switch. In cold regions with freezing time longer than 3 months, the operation can be pre-determined accordingly for a flocculation, thickening, and deposition operation, then switching to a freezing-thawing cyclic operation which needs some time next year for the thawing operation.
In some embodiments, there is a method to improve the settling and water recycle within the runoff collection pond. The method includes: a) Splitting the runoff collection pond into more than one runoff collection cells by a number of floating dividers, one floating divider can separate the runoff collection pond into two cells, two floating dividers for three cells, and three floating dividers for four cells, and so on. b) Connecting one of the two ends of the floating dividers perpendicularly to the floating dyke, and locating the other end to the coarse tailings beach area. c) Operating the separated runoff collection cells rotationally to develop required beach area and split the runoff fluid tailings for water recycle and fluid tailings treatment after settlement for a certain time.
In some embodiments, there is a method for the fluid tailings treatment by flocculation. The flocculation operation is carried out at a flocculation station. The flocculation station comprises: a) a flocculant solution preparation unit, b) a set of flocculant solution storage vessels, c) a set of flocculation pipelines, and d) an operation platform with a set of equipment skids. The flocculation station can be located on shore area, or on a floating platform attaching to the floating dyke.
In some embodiments, the fluid tailings can be treated through flocculation include: a) fine tailings from processing plant, b) fine tailings from the runoff collection cell, c) fluid tailings from the tailings pond, d) coarse tailings from the processing plant, e) off-spec recycle water from the treatment systems within the tailings pond, and f) any combinations of tailings from a to e.
In some embodiments, there is a method to provide tailings ponds with multi-functions: a) separating the storage and management of fluid tailings and water, b) rapid treating fluid tailings and recovering classified process waters, c) in-situ depositing treated tailings, d) simultaneously reclaiming tailings pond during mining operation and completing the reclamation right after the mine closure, and e) providing a great flexibility for planning of short- to mid-term tailings and water management and tailings pond development.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 is a side view of conventional tailings pond.
Figure 2 is a side view of new tailings pond with floating dyke and floating bottomless thickener.
Figure 3 is a plan view of new tailings pond with floating dyke and floating thickener.
Figure 4 is a side view of existing active tailings pond with floating dyke, floating bottomless thickener, water holding cell, and fluid tailings holding cell.
Figure 5 is a side view, of new tailings pond after the first relocation of floating dyke and floating bottomless thickener.
Figure 6 is the structure of floating dyke and dividing sheets across the tailings pond.
Figure 7 is the structure of single piece of dividing sheet hanging below the floating dyke.
Figure 8 is the operation sequence of a zoned bottomless thickening area.
Figure 9 shows a network of sand-caps and sand-walls in thickened tailings deposits in bottomless thickener.
DETAILED DESCRIPTION OF THE INVENTION
In the following detailed description section, specific embodiments of the present invention are described. However, to the extent that the following description is specific to a particular embodiment or a particular use of the present invention, this is intended to be for exemplary purpose only, and simply provides a description of the exemplary embodiments. It is worth noting that the methods and devices of the present invention are not limited to the specific embodiments described below, but rather, include all alternatives, modifications, and equivalents falling within the scope of the appended claims.
As mentioned before, the mining industry is facing a great challenge to deal with the fluid tailings in tailings pond. The present invention provides a new solution to achieve handling and treatment of fluid tailings, management of treated tailings depositions, and management of recycle water and fresh make up water in tailings pond, and simultaneous reclamation of tailings pond. There is no similar approach as the present invention in the mining industry, or in the R&D areas for the handling, treatment, and management of fluid tailings in tailings pond, and the reclamation of tailings pond.
The following provides some exemplary details of the invention. Figure 1 is the side view of a conventional tailings pond with its major structure and tailings materials in it. The tailings pond is impounded by the dams 101 and 106, there are two fresh tailings streams fed into the tailings pond, that is, the coarse tailings 110 that is discharged on the coarse tailings beach 102, and fine tailings 109 that is discharged into the fluid body of the tailing pond. Two types of beaches form during tailings deposition, including: a) the above-water-beach 102 that is formed above the water surface by the coarse sands in the coarse tailings, and b) the under-water-beach 103 that is formed below the water surface by the combination of the coarse part of the runoff of coarse tailings stream 110 and the coarse part of the fine tailings stream 109. The very fine particles remaining in fluid tailings from the runoff of coarse tailings 110 and fine tailings 109 join together to form a slow flowing and diffusive suspending fluid tailings body 104 in tailings pond. Over the time after diffusion, settling, and segregation of solid minerals in fluid tailings, the rest fluid tailings body in tailings pond becomes stable and three distinct layers are observed, including a consolidated tailings layer 105 at the bottom of the pond, a fluid tailings layer 107 in the middle of the pond, and a thin water layer 108 at the top of the pond. It is the middle fluid tailings layer that retains a huge amount of water with fine mineral particles, and takes the most volume of the tailings pond.
And the quality of the top water that is used as recycle water 111 is affected significantly by the middle fluid tailings because the top water layer is thin, and the composition of the water varies with various conditions that bring fine particles from the fluid tailings into the top water layer, such as seasonal and daily temperature fluctuations, strength of wind, relocation of fresh tailings discharge points, and ore quality fluctuations. Therefore, the major challenge for the conventional tailings pond is how to deal with the fluid tailings middle layer 107 in order to improve the top water quality, reduce the volume of fluid tailings in the pond, and start up the reclamation of the pond.
The.present invention discloses a method to solve the problem that the conventional tailings pond has. Figure 2 shows the side view of the tailings pond with the embodiments of the method in details. The tailings pond is a new pond, meaning there are no old fluid tailings in the pond; instead, the tailings pond is pre-filled with only fresh water 108 for starting up a mining operation. The major difference in arrangements of tailings pond between the conventional and the invention is the addition of two devices, that is, a) the floating dyke 201, and b) the floating bottomless thickener 202 in the tailings pond. The floating dyke separates the tailings pond into two sections: a) the runoff collection section 205, and b) the remaining fresh water section 108.
After the coarse tailings 110 is discharged onto the coarse tailings beach, the runoff part of the coarse tailings 110 that flows into the fluid body of the tailings pond is stopped by the floating dyke 201 from flowing further into the fresh water body. After certain times, the runoff collected in the runoff collection section separates into three layers: a) the under-water-beach 103 on the top of the old beach 102, b) the high solids content fluid tailings 205, and c) the low solids content top water 208. Although the solids content in the top water 208 is still high for processing reuse, the quality is good enough for the top water to be used as process dilution 208 for tailings transportation purpose.
The high solids content fluid tailings 207 in the runoff collection section combines with the fine tailings 109 from the processing plant to report to the flocculation station 204 for flocculation treatment, and then report to the floating bottomless thickener 202 for thickening. The flocculated fluid tailings are thickened within the bottomless thickener; the thickened tailings are settled downward to the bottom of the tailings pond just below the bottomless thickener to from a new part of the under-water-beach 206.
The released wann water 203 within the bottomless thickener is directly recycled back to the processing plant as recycle water 209. There are several advantages for the arrangements of the invention: a) cutting down the flow path of the runoff and the fine tailings into the main fresh water body of the tailings pond, so as to avoid adding fine particles into the existing fresh water body, b) fixing down the fine particles within the pre-determined areas through flocculation, thickening, and in-situ deposition processes within the bottomless thickener, at the same time, recover the warm water through the thickening process, c) using different tailings deposits to build up the under-water-beaches for preparation of tailings pond reclamation, and d) reducing the tailings pond size and increasing the flexibility of operation planning through reducing the fluid tailings volume, improving the water quality, and reclaiming the tailings pond simultaneously.
Figure 3 further shows some details of the arrangements in plan view of the tailings pond. There are several features in the arrangement: a) the floating dyke 201 goes across the whole pond surface at one corner of the tailings pond, with its two ends next to the shoreline, b) the runoff collection section 205 is further separated into three cells by two floating dividers 301, each of the floating dividers 301 has one end connected perpendicularly to the floating dyke 201, the other end fixed to the shoreline, so the two parallel floating dividers form three runoff collection cells in parallel arrangements toward the coarse tailings beach, c) a common connection pipeline 207 is set across the three runoff collection cells 205 to transport the runoff fluid tailings 207 into the flocculation station 201, d) two types of the floating bottomless thickeners, one in round shape 202b, the other in rectangular or square shape 202a, are set next to the floating dyke 201. The arrangements provide more advantages for the operation, including: a) the multiple runoff collection cells allow for the coarse tailings beaching at different beach areas for beach development, and for the runoff settling in different cells for a long time for sufficient separation, b) the two bottomless thickeners allow for more flexible fluid tailings thickening, such as different tailings treatment at the same time in different thickeners, or in a sequential operation in the same thickener; a staged treatment from the first thickener to the second thickener if the water quality in the first stage does not meet the requirements. Furthermore, the arrangement makes the water management easy to classify the water bodies in terms of water quality and flow rates required.
For more common scenarios in current mining operations, there would be existing active tailings ponds before the present invention is used for improvement of tailings and water management in the operations. Figure 4 depicts the embodiments of the method, and some more detailed exemplary descriptions are given below. The difference between the existing active tailings pond and the new tailings pond is in that the new tailings pond holds only fresh water, while the existing active pond holds fluid tailings in most of its fluid body. The new tailing pond can be easily to start up the thickening process after the bottomless thickener is installed, however, the existing active tailings pond needs to be arranged to get rid of the fluid tailings out of the bottomless thickener, and fill up the bottomless thickener with process water. As shown in Figure 4, the operation is realized by the following steps: a) setting up the floating dyke 201 to separate the runoff collection section 205 and the main tailings pond section 107 and108, b) starting up the runoff collection, settling, recycling dilution water 208 back to the processing plant, transferring the fluid tailings 207 into the main tailings pond, and building up the under-water-beach 103 below the runoff collection section 205, c) using the floating dividers 202 and combining with the floating dyke 201 to form at least one of the floating bottomless thickener 202, d) filling up the floating bottomless thickener 202 by pumping the top water 108 of the tailings pond until the water level in the bottomless thickener 202 is higher than the water level of the tailings pond or achieves constant high level, e) starting up the flocculation and thickening process from the runoff collection section or cells 205, recycling walui process water 209 for process reuse, and depositing the thickened tailings in-situ down to the bottom of the tailings pond to form the under-water-beach 206, and f) relocating the floating bottomless thickener 202 along the floating dyke 201 to continue the flocculation and thickening process, and building up the under-water-beach 206 along the floating dyke 201 until the building of the under-water-beach is completed.
Because the fluid tailings is still holding the major volume of the main tailings pond, the present invention proposes some embodiments to speed up the treatment of fluid tailings in the main tailings pond, and improve the recycle water quality, so as to eliminate or mitigate the impact of the fluid tailings on the mining operation. Figure 4 depicts some details with two floating closed cells for the treatment and management purpose. The operation steps include: a) setting up two floating closed cells 401 and 402 by using floating dividers 202, and choosing one of the floating closed cell as a water-holding cell 401, and the other as a fluid tailings-holding cell 402, b) withdrawing the top water out of the fluid tailings-holding cell 402 until the top water layer disappears, then transferring the fluid tailings 403 in the fluid tailings-holding cell to the flocculation station 204 for treatment, c) filling up the top water into the water-holding cell 40 luntil the water level is higher than the water level in the main tailings pond or achieves a constant high level, then transferring the water for process recycle 111. There are many other alternatives through combinations of the floating dykes 201 and floating dividers 202 to form various open or closed cells for fluid tailings treatment, fluid tailings holding, recycle water holding, treated tailings in-situ deposition, in-pond deposition, or out-of-pond deposition, and to make the tailings and water management more flexible at a low cost.
The continuous development of the above-water beach and the under-water-beach can be looked as a part of tailings pond reclamation, the volume reduction of tailings pond follows simultaneously.

The operation steps for the tailings pond reclamation include: a) determining the area to be reclaimed, setting up the boundary, b) installing the floating dyke to cover the area to be reclaimed, and installing the floating bottomless thickener next to the floating dyke, c) starting up the coarse tailings beaching process to build up the above-water-beach, collecting the runoff, building up the under-water-beach in the runoff collection section, and treating the runoff fluid tailings, d) starting up the flocculation, thickening, and treated tailings deposition process, and building up the under-water-beach in the deeper side of the floating dyke, e) continuing the beach construction in the three areas until the under-water-beaches are fully developed along the two sides of the floating dyke, and 0 relocating the floating dyke forward for a new round of operation, and moving the coarse tailings discharge point forward to develop the above-water-beach to cover the under-water-beach that was built up during the last round of operation. The exemplary description for the beach status after the completion of the first round of tailings pond reclamation is shown in Figure

5. A new beach layer 501 formed from the combination of the new above-water-beach and the old under-water-beach moves forward and deposits on the top of old beach layer 102. The new under-water-beaches 103 and 502 are developed in the same way as the previous round of operation. The old under-water-beach 206 developed from the treated tailings deposits is next to the new beach layer 501 and becomes a part of the under-water-beach 103 in the new runoff collection section 205. Although there is no direct indication for the reduction of the pond size, it is obvious that the tailings pond volume is reduced due to the beach moving forward to the fluid pond end. It is worth noting that the arrangements are flexible and ready for changes to meet the requirements for different purposes.
The floating dyke is one of the key devices in the present invention. There are many ways for the construction of a floating dyke, such as using floating docks, barges or boats, suspending cables, and supporting poles, to hang the dividing sheets. Figure 6 is an exemplary design for the floating dyke.
The floating dyke comprises: a) a hanging cable 602, b) group of dividing sheets 604, c) a group of floating dock modules 606, and d) a group of height adjusting mechanisms 605.
A pair of pillars 601 that are fixed on the shore fixes the hanging cable 602, and the hanging cable 602 hangs the dividing sheets 604 and guides the floating dock modules 606 in positions required. The dividing sheets 604 are connected together through adhesive strips or patches 607 that are attached on the edges of the dividing sheets. The whole dividing sheet hangs below the hanging cable, left about 0.5 in to 1.0 in above water surface, and about 1.0 m to 3.0 m gap at the bottom of the tailings pond 608. The side edge of the dividing sheet is trimmed to tightly connect to the slope of the dam 609. The height adjusting mechanisms 605 are used to adjust the gap between the pond bottom 608 and the dividing sheet 604. During the relocation, the adjusting mechanisms are used to pull the whole dividing sheet up close to the water surface, and to set up a new height required in a new location.
Figure 7 shows more details for a single piece of dividing sheet hanging below the floating dyke, as well as the arrangement of floating devices at the water surface level. As an exemplary design in Figure 7, the floating devices 606 form a walkway 703 at the water surface level, and there are handrails 702 on both sides of the walkway. The dividing sheet 604 hangs on one side of the handrail 702 through a set of hooking mechanism 701. There is a group of Velcro patches 607 on one side of the dividing sheet 604 for connection to another dividing sheet.
Below the dividing sheet is a group of heavy balls 704 that are used to stretch the dividing sheet by the weight of the balls.
The height adjusting mechanism 605 links to the bottom of the dividing sheet 604, and controls the height of the dividing sheet 604 from the handrail level 702 where the hanging mechanism is located.
As mentioned before, the design of floating dividers is similar to the floating dykes, although there is no walkway attached to the floating dividers. In most scenarios, the floating dividers form various open or closed cells for different purposes, such as cell dividers, zone dividers, bottomless thickeners, water-holding cells, fluid tailings-holding cells, and the combinations of above mentioned cells or zones. The combinations of floating dykes and floating dividers are also flexible, and can be used for any kind of applications as mentioned above.
Another key device in the present invention is the floating bottomless thickener. As a matter of fact, a floating bottomless thickener is an operational area that is enclosed by a floating device and a dividing sheet. Although the top of the area is open, the fluid in the surrounding area cannot flow into the enclosed area, neither from the top, nor from the side-dividing sheet. However, the bottomless design provides the opportunity for fluid flow through the bottom area, the present invention makes use of the design to realize the fluid management and treatment within a single operational area, particularly for operations of tailings treatment and tailings pond reclamation. The present invention discloses a method for design and use of a floating bottomless thickener, the method includes two aspects: a) determination of the bottomless thickening area, and b) the thickening operation within the pre-determined area. Because the purpose of thickening process is to improve water release from fluid tailings, the thickening area can be anywhere within the tailings pond, however, if there are more goals to be targeted, the selection of thickening area is constrained to certain areas. Taking the tailings pond reclamation as an exemplary case, the best location for the thickening operation is close to the beach area where the upcoming reclamation will occur. In this case, the floating dykes and the floating dividers can be located to the said area to start up the construction of the under-water-beach through the thickening and in-situ deposition operation that the present invention discloses. Taking the reclamation of an existing inactive tailings pond as another exemplary case, the objective of the operation is to release water from the pond without reduction of the pond volume. In this case, the thickening area can be anywhere in the tailings pond, however, the best location is the deepest area where the thickening operation will last longest time before the bottom is filled up for relocation.
The thickening operation is also important for the bottomless thickener to achieve the highest efficiency. Figure 8 shows an exemplary embodiment for a zoned thickening area, and the thickening operation within the enclosed area. As shown in Figure 8, the shape of the thickening area is rectangular, in order to achieve the best performance of the thickening devices, the area is split into eight zones in two parallel rows with four zones in each row. There are two feedwells for the thickening operation at the same time. The two feedwells 801 and 804 are arranged in diagonal positions in zone 1 and zone 5 respectively, so there is the least impact between the two feedwells during the thickening operation. Each feedwell follows the pre-determined directions 802 to move.
The thickening operation will take certain time at each zone to build up the thickened tailings deposits layer, then move to the next zone. There may be more feedwells required for different purposes.
Figure 9 shows an exemplary result from a periodic thickening and sand-capping operation. The resulting network of sand-caps 905 and sand-walls 906 within the thickened tailings deposits 904 is constructed after the rotating operation. The detailed operation steps are described below: a) using the feedwell 901 for thickening and sand-capping operation, b) starting up the thickening first to build up the bottom layer of the thickened tailings deposits that is placed on the old deposits 908, c) capping sands layer on top of the thickened tailings deposits, d) setting up a set of paired floating dividers within the bottomless thickener to split the thickening area into isolated zones by the paired floating dividers, e) depositing coarse sands within the paired floating dividers to form sand-walls progressively, f) repeating the thickening, sand-capping, and sand-wall building until the deposits reach the feedwell, and g) remove the floating dividers from the sand-walls and relocating the thickening area for next round of operation. Although there is only one feedwell 901 in Figure 9, more feedwell in different types or different sizes may be needed for different feed streams at the same time within different zones as mentioned in the case of Figure 8.

Claims (48)

20

1. A method for management and rapid treatment of fluid tailings, and in-situ deposition of the treated tailings within a tailings pond, as well as simultaneous reclamation of the tailings pond. The said method comprises: a) using a floating dyke to separate a tailings pond into two sections, one section is shallower, and linked to an above-water-beach area, the other section is toward the deeper side of the tailings pond, b) using the section linked to the beach area as a runoff collection pond to collect the runoff fluid tailings that are overflow from the above-water-beach area, and to form a part of under-water-beach in the shallow side of the floating dyke, c) using a floating divider and combining with the floating dyke to form a bottomless thickener along the deeper side of the floating dyke, d) flocculating various fluid tailings that are derived from the processing plant and/or from the runoff collection pond through a flocculation station, e) depositing the flocculated tailings within the bottomless thickener for thickening and dewatering, f) recovering water from the top of the bottomless thickener, and developing a thickened tailings deposits layer at the bottom of tailings pond below the bottomless thickener, g) relocating the bottomless thickener along the floating dyke, and repeating the steps c to f to continue the development of under-water-beach along the deeper side of the floating dyke until the depth of the treated tailings deposits meets the reclamation requirements, h) setting up a new runoff collection and bottomless thickening system by relocating the floating dyke and the floating bottomless thickener downstream of the under-water-beach, and starting the tailings pond reclamation by forwarding the above-water-beach to cover the under-water-beach formed in previous steps a to g, and i) repeating steps a to h until the completion of the tailings pond reclamation.

2. The method of claim 1, wherein the tailings pond can be: a) an in-pit tailings pond, b) an out-of-pit tailings pond, c) a new tailings pond holding prefilled fresh water for fresh incoming fluid tailings storage, d) an existing active tailings pond holding fluid tailings with a top water layer for fresh incoming fluid tailings storage, and e) an existing inactive tailings pond holding fluid tailings with a top water layer without fresh tailings input.

3. The method of claims 1 and 2, wherein the tailings pond can be a tailings storage facility for:
a) oil sands mining operation, b) coal mine, c) metallurgical mining operation, d) metal and metal oxide mining operation, d) phosphate mining operation, and e) china clay mining operation.

4. The method of claim 1, wherein the fluid tailings can be: a) coarse sand tailings, b) fluid fine tailings, c) mature fine tailings, d) runoff of coarse sand tailings, e) off-spec recycle water from treatment systems, and 1) any combinations of a to e.

5. The method in claims 1-4, wherein the tailings pond is an existing active pond with fluid tailings in it. In addition to the steps a to i of claim 1 for fresh tailings treatment and deposition, there are extra steps needed to set up the bottomless thickener for quickly starting up the thickening operation in the existing tailings pond, although the method of claim 1 can be directly used. The extra steps comprise: a) using a floating divider to set up a closed cell next to the floating dyke, b) withdrawing the top water from the tailings pond and feeding the water into the closed cell from the top until the water level is higher than the top water level of the tailings pond and reaches constant, c) converting the closed water holding cell to a thickening cell by discharging the flocculated tailings into the closed water holding cell, and d) starting normal thickening and deposition operations as mentioned in claim 1.

6. The method in claims 1-5, wherein the tailings pond is an existing inactive pond with fluid tailings in it, however, there is no fresh tailings fed into the tailings pond. The method of claims 1 and 5 can be simplified to the following steps: a) using two floating dividers to set up two closed cells with or without direct connection each other, b) leaving the bottom of the two closed cells open and connected to the existing fluid tailings, c) choosing one of the two cells for water holding, and the other one for fluid tailings holding, d) withdrawing the top water out of the fluid tailings holding cell until the top water layer disappears, e) withdrawing the top water from the tailings pond or from the fluid tailings holding cell, and feeding the water withdrawn into the water holding cell until the water level is higher than the top water level of the tailings pond and reaches constant, f) converting the water holding cell to a thickener by flocculating the fluid tailings in the fluid tailings holding cell, and discharging the flocculated tailings into the water holding cell, g) discharging water from the water holding cell to tailings pond through overflow or recovering water from the water holding cell, and depositing the thickened tailings to the bottom of the tailings pond below the water holding cell, h) relocating the water holding cell after the depth of the deposits meets the reclamation requirements or reaches the operation limits, i) repeating steps a to h until the completion of the fluid tailings treatment in the whole tailings pond, and j) starting tailings pond reclamation during or after step i by reducing top water volume, s.and-capping the thickened tailings deposits, and landfilling with solid materials along the shoreline of the tailings pond.

7. The method of claims 5 and 6, wherein the fluid tailings in the fluid tailings holding cell can be handled in different ways in different seasonal conditions. In warm seasons, including spring, summer, and fall, the fluid tailings can be flocculated and thickened in the water holding cell and deposited within the tailings pond below the water holding cell, or flocculated and deposited in the beach area close to the shoreline below or above water surface. In cold winter season, the fluid tailings can be treated by spreading the fluid tailings on top of the deposits that were deposited during the warm seasons, or on the ice surface close to the shoreline. The ice layer will be thawed in the coming year and form a new tailings deposition layer on the top, then the process can be repeated to add more flocculated tailings on top of the thawed tailings layer until the fluid tailings in the tailings pond are treated completely, and further tailings pond reclamation with sand-capping can follow.

8. The method of claims 1-7, wherein the operations for tailings treatment and deposition can be done in a periodical manner. The rotating period of time can be a month, three months, six months, and 12 months, or in terms of seasonal weather conditions.
Particularly in warm region, the flocculation, thickening, and deposition can be done in a whole year without a long-term operation switch. In cold region with the summer is 3 months, the winter is 7 months, and the spring and fall seasons are one month each, the operation can be pre-determined accordingly for a five-month flocculation, thickening, and deposition operation, then switching to a five- to six-month freezing operation, and followed by a three- to four-month thawing operation next year with the rotating operations on the pre-determined deposition areas accordingly.

9. The method of claim 1, wherein the floating dyke is a device that has multiple functions, including: a) separating the tailings pond into sections, b) forming confined cells in tailings pond, c) positioning various floating operation systems, and d) providing access for operation and maintenance. The floating dyke comprises: a) a hanging device above water surface, b) a dividing sheet hanging along the hanging device and immersing down close to the bottom of the tailings pond, c) an above water walkway attaching to the hanging device, d) an above water platform attaching to the above water walkway, e) a positioning system along the hanging device from one end to another, including pillars, anchors, hooks, guiding cables, and linkages between the floating devices, the hanging device, the dividing sheet, and the positioning devices, and f) a number of connection systems to link the floating dividers for setting up various open or closed cells linked to the floating dyke, including runoff collection cells in the shallow side of the floating dyke, and the bottomless thickener in the deeper side of the floating dyke.

10. The method of claims 1 and 9, wherein the hanging device of the floating dyke has a set of floating devices to hang the dividing sheets above the water surface at required locations.
The floating devices include: a) floating docks, b) floating platforms, c) floating working structures, d) chained barges or boats, e) chained pipe bundles, f) chained drum bundles, and g) any combinations of a to f

11 . The method of claims 1 and 9-10, wherein the hanging device of the floating dyke has a set of supporting devices that are used to hang the dividing sheets above the water surface at required locations. The supporting devices include: a) suspending cable systems, b) above water working platforms, c) above water walkways or access roads, d) mobile pillars and poles to support the hanging systems, and e) any combinations of a to d.

12. The method of claims 1 and 9-11, wherein the hanging device of the floating dyke can be any combinations of the floating devices of claim 10 a to g and the supporting devices of claim 11 a to e.

13. The method of claims 1 and 9, wherein the floating divider is a device that has two functions: a) separating the tailings pond into cells, and b) forming confined cells in tailings pond. The floating divider comprises: a) a floating dock, b) a dividing sheet hanging along the floating dock and immersing down close to the bottom of the tailings pond, and c) a positioning system along the floating dock to form the connections to other floating devices or positioning devices, including pillars, anchors, hooks, guiding cables, and other positioning devices.

14 . The method of claims 1-13, wherein the floating dykes and the floating dividers can be placed in tailings pond at the depth of about 5 m to 65 m, the preferred location has a depth in the range of 15 m to 35 m.

15 . The method of claims 1-14, wherein the height of the dividing sheet of the floating dykes or the floating dividers depends on the depth of the tailings pond where the floating dykes or the floating dividers is installed. The total height of the dividing sheet of the floating dykes or the floating dividers includes: a) above water surface portion, and b) below water surface portion. The above water surface portion of the floating dykes or the floating dividers is kept about 0.5 m to 1 m above the pond water surface. The below water surface portion is determined by the depth of the tailings pond. The dividing sheet of the floating dykes or the floating dividers can reach the bottom of the tailings pond, so the total height of the dividing sheet is in a range from 6 m to 60 m. A gap of about 0.5 m to 5 m between the dividing sheet and the bottom of tailings pond is arranged to keep the deposits spreading along the bottom of the tailings pond, so the height of the dividing sheet of the floating dykes or the floating dividers can be shorter. The preferred gap between the dividing sheet and the tailings pond bottom is in the range of 1m to 3 m at the beginning of the thickening operation.

16. The method of claims 1-15, wherein the height of the dividing sheet of the floating dyke or the floating dividers is adjustable, so the floating dykes or the floating dividers associated with its dividing sheet can be relocated to any locations in the tailings pond without major change in its structure.

17. The method of claims 1-16, wherein the gap between the dividing sheet of the floating dykes or the floating dividers and the tailings pond bottom is adjustable, so the under-water-beach between the dividing sheet of the floating dyke can be connected directly at the pond bottom up to many meters above the pond bottom level, depending on the depth of the thickened tailings deposits. The adjustable gap is in a range of 3 m to 55 m, the preferred adjustable gap is in the range of 5 m to 25 rn. The adjustable mechanism can be a group of rope-linked adjustment systems that adjust the dividing sheets up and down when the adjustment is required.

18. The method of claims 1-17, wherein the dividing sheet of the floating dykes and the floating dividers can be left in place as reinforcement structure during the relocation, only the floating part of the floating dykes and the floating dividers is removed from the operation for building up new floating dykes and floating dividers.

19. The method of claims 1-18, wherein the floating dyke can be placed toward a small part of beach area, the runoff collection section can be used to collect the runoff intermittently, so as to allow for the runoff collected settling for a longer period of time. The other side of the floating dyke can still be used for the flocculation, thickening, and deposition operations.

20. The method of claims 1-19, wherein the floating dyke can be placed cross a wider range of the tailings pond to form two large pond sections, each section can be alternately used for runoff collection and fluid tailings flocculation, thickening, and deposition for a longer period of time.

21. The method of claims 1-20, wherein more than one floating dykes can be installed in a tailings pond in different areas at the same time to perform operations of claims 1-20.

22 The method of claims 1-21, wherein a floating dyke can be used with its both sides to form bottomless thickener for fluid tailings treatment and deposition.

23. The method of claims 1-22, wherein a floating dyke can be added parallel to another floating dyke to form a closed section in the tailings pond. This closed section can be used for: a) a cell for thickening and deposition, b) a cell for water holding, and c) a cell for fluid tailings holding.

24. The method of claims 1-23, wherein one or more floating dykes can be connected to other floating dykes to form multiples closed cells at different locations in the tailings pond. These closed cells can be used for: a) cells for runoff collection, b) cells for thickening and deposition, c) cells for water holding, d) cells for fluid tailings holding, and e) cells with function of a to d, switching to another function of a to d.

25 The method of claims 1-24, wherein one or more floating dykes can be connected with one or more floating dividers to form multiple closed cells at different locations in the tailings pond. These closed cells can be used for: a) cells for runoff collection, b) cells for thickening and deposition, c) cells for water holding, d) cells for fluid tailings holding, and e) cells with function of a to d, switching to another function of a to d.

26. The method of claims 1-25, wherein one or more floating dividers can be connected with one or more floating dividers to form multiple closed cells at different locations in the tailings pond. These closed cells can be used for: a) cells for runoff collection, b) cells for thickening and deposition, c) cells for water holding, d) cells for fluid tailings holding, and e) cells with function of a to d, switching to another function of a to d.

27 The method in claim 1, wherein the runoff collection pond can be further split into more than one runoff collection cells. The runoff collection cells are formed by a number of floating dividers, each of the floating dividers has one end connected perpendicularly to the floating dyke and the other end extended to the above-water-beach. One floating divider can separate the runoff collection pond into two cells, two floating dividers for three cells, and three floating dividers for four cells, and so on. With the separated runoff collection cells, the above-water-beach can be developed in a rotating way and allow for the runoff collected settling for a certain time required for water recycle and fluid tailings treatment. The runoff collection cells can also be switched to a bottomless thickener if needed. The number of runoff collection cells is in a range of 2 to 5, the preferred number of runoff collection cells is 3.

28. The method of claim 1, wherein the flocculation operation is carried out at a flocculation station. The flocculation station comprises: a) a flocculant solution preparation unit, b) a set of flocculant solution storage vessels, c) a set of flocculation pipelines, and d) an operation platform with a set of equipment skids. The flocculation station can be located on shore area, or on a floating platform attaching to the floating dyke.

29. The method of claims 1 and 28, wherein the flocculation operation in the flocculation station include: a) fine tailings from processing plant, b) fine tailings from the runoff collection cell, c) fluid tailings from the tailings pond, d) coarse tailings from the processing plant, e) off-spec recycle water from treatment systems within the tailings pond, and f) any combinations of tailings from a to e.

30. The method of claim 1, wherein the bottomless thickener is a device that has a simple configuration, including: a) a peripheral border to define the settling area of the thickening operation and the depth of the thickener, b) one or more feedwells with distributors at the outlet of the feedwells, c) a skimming mechanism to collect the free bitumen or free floats at the top of water surface, and free bitumen and floats collection well, and d) a water recovery transport well.

31. The method of claims 1 and 30, wherein the bottomless thickener can be further simplified to have: a) a peripheral border to define the settling area and the depth of the thickener, and b) a feed pipe with a distributor at the outlet of the pipe.

32. The method of claims 1 and 30-31, wherein the peripheral border of the bottomless thickener can be form by: a) a floating dyke, b) a floating divider, c) a combination of a floating dyke and a floating divider, and d) other floating devices with dividing sheet hanging below the floating devices.

33. The method of claims 1 and 30-32, wherein the shape of the bottomless thickener can be: a) circles, b) squares, c) rectangles, d) triangles, and e) any combinations of a to d. The preferred shape is rectangular.

34. The method of claims 1 and 30-33, wherein the size of the bottomless thickener is variable, depending on the treatment required. The size is in a range of 100 m2 to 100000 m2, and the preferred size is in the range of 5000 m2 to 10000 m2.

35. The method of claims 1 and 30-34, wherein both the size and shape of the bottomless thickener are adjustable through the change in connections and positioning of various floating devices.

36. The method of claims 1 and 30-35, wherein the height of the sidewall of the bottomless thickener determines the depth of the thickener. However in most cases, floating dykes and/or floating dividers form the bottomless thickener, so the height of the sidewall has been pre-determined at the beginning of the thickening operation. The depth for thickening and depositing operations is in a range of 5 m to 60 m, the preferred depth is in the range of 8m to 35 m. The height of the sidewall of the bottomless thickener can be adjusted within the range of 5 m to 35 m in terms of the progress of the thickening and deposition operations.

37. The method of claims 1 and 30-36, wherein the bottomless thickener can be used as a clarifier when the recycle water from a bottomless thickener needs to be further treated. The treatment system becomes a two-stage treatment system, the first stage is a bottomless thickener, and the second stage is a bottomless clarifier. It is preferred that the treatment system has two bottomless thickeners to act as a two-stage treatment system if required.
Alternatively, one of the runoff collection cells can be used as the first stage bottomless thickener if the second bottomless thickener does not exist in the deeper side of the floating dyke.

38.A method for enhancement of dewatering and strengthening of thickened tailings deposits during the thickening and deposition operations within the bottomless thickener. The method comprises: a) splitting the bottomless thickener into two zones, b) starting from zone 1 with flocculation, thickening, and deposition of fluid tailings to build up 2 in to 3 in thickened tailings deposits, c) moving to zone 2 to continue the flocculation, thickening, and deposition of fluid tailings to build the same depth of deposits, at the same time in zone I , using coarse tailings to do flocculation, thickening, and deposition to build up 0.5 m to 1 m thickened coarse tailings deposits as sand-cap on top of the thickened fine tailings deposits, d) repeating the operation in the sequence to build up the deposits layers until the total depth of the deposits meets the reclamation requirements or reaches the operation limit, and e) relocating the thickener to another location. The depth of the deposits is in a range of 5 m to 65 rn, the preferred depth of deposits is in the range of 8 m to 35 m.

39. The method of claim 38, wherein the bottomless thickener can be split into multi-zones within the enclosed thickening area, the number of zones depends on the minimum settling area required, the actual settling area in each zone should be one to ten times of the minimum settling area. The preferred zone area is in the range of two to five times of the minimum settling area.

40. The method of claims 38-39, wherein the bottomless thickener can be split into multi-zones by adding a group of floating dividers. The floating dividers work parallel to form a series of narrow gaps between each thickening zone, the thickening and deposition operations within the thickening zones are the same as claims 38-39, while the gaps between the floating dividers are used to deposit the flocculated coarse tailings to form a series of coarse sand walls between each thickening zone. This operation forms a sand network within the deposits, so as to enhance the dewatering and strengthening process of the thickened fine tailings. The distance between two nearest sand walls is in a range of 5 m to 50 m, the preferred distance is in the range of 10 m to 30 m. The thickness of each vertical sand wall is in a range of 0.5 m to 5 m, the preferred thickness is in the range of 1 m to 2 m. The floating dividers can be relocated after the operation, however, the whole floating dividers or a part of the floating dividers can be left in place as reinforcement structure after the operation.

41 . The method of claims 38-40, wherein the bottomless thickener can be split into multiple thickening zones, the thickening and deposition operations can be done the same as claims 38-39, while a series of floating dividers that form a series of closed columns are placed and distributed evenly into the thickener. With the thickening and deposition operation continued in the thickening zones, the flocculated coarse tailings are deposited into the columns formed by the floating dividers. When the thickening and deposition operations are completed, a coarse sand network is formed within the deposits, so as to enhance the dewatering and strengthening of thickened fine tailings. The interval of sand column is in a range of 5 m to 50 m, the preferred interval is in the range of 10 m to 30 m. The shape of the sand column can be circle, square, rectangle, or triangle, or irregular shapes. The cross-sectional area of the sand column can be in a range of 1 m2 to 10 m2, the preferred cross-sectional area is in the range of 2 m2 to 4 m2. The floating dividers can be removed from the deposits after the operation for reuse.

42. The method of claims 38-41, wherein the coarse tailings can be deposited into the thickened tailings deposits without flocculation.

43. The method of claims 38-42, wherein the coarse tailings can be other coarse materials, particularly for the building of the vertical sand-walls or the vertical sand-columns. The coarse solid materials include: a) coarse sands with an average particle size larger than 90 microns, b) delayed cokes, c) solid minerals with an average particle size larger than 75 microns, and d) solid wastes with an average particle size larger than 0.5 mm.

44 The method of claims 38-43, wherein the coarse tailings are deposited and distributed evenly on top of the thickened tailings by a coarse tailings discharge distributor that is driven by a horizontal moving device. The moving coarse tailings discharge distributor comprises: a) a vertical fishtail-like distributor, b) a series of rods installed in the tip of the distributor for plowing of the deposits, and c) a flat board that is falling on the top of the deposits and towed by the distributor for pressing and smoothing the deposits.

45. The method of claims 1-26 and 30-37, wherein the floating dykes and the floating dividers may have an additional thermal insulation layer attached to the dividing sheet at the upper section of the dividing sheet, particularly for cold regions in winter time.
The height of the insulation layer is in a range of 2 m to 10m, the preferred height of the insulation layer is in the range of 3 m to 5 m.

46. The method of claims 1-26 and 30-45, wherein the materials for the dividing sheets that are used in both the floating dykes and the floating dividers include: a) woven or non-woven geotextile, b) woven or non-woven cloth, c) non-permeable and semi-permeable polymer membrane or thin film, including plastics, rubber, and composite materials, d) water permeable networks, including metal and non-metal meshes, nets, webs, and filter media, and e) any combinations of a and d.

47. The method of claims 1-26, 30-46, wherein the dividing sheets are made from small pieces of materials of claim 46 by the following means: a) zippers, b) adhesives, c) sewing, d) Velcro strips or patches, and e) any combinations of a to d.

48.A method to provide tailings ponds with multi-functions, including: a) separating the storage and management of fluid tailings, tailings deposits, fresh water, and process recycle water, b) rapid treating fluid tailings and recovering classified process waters, c) in-situ depositing treated tailings, d) simultaneously reclaiming tailings pond during mining operation and completing the reclamation right after the mine closure, and e) providing a great flexibility for short- to mid-term planning of tailings and water management and tailings pond development.