Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D3/00—Differential sedimentation
  • B03D3/06—Flocculation
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
  • C02F1/56—Macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/008—Sludge treatment by fixation or solidification
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/10—Nature of the water, waste water, sewage or sludge to be treated from quarries or from mining activities

Definitions

• the present invention relates to the treatment of mineral material, especially waste mineral slurries.
• the invention is particularly suitable for the disposal of tailings and other waste material resulting from mineral processing and beneficiation processes, including the co-disposal of coarse and fine solids, as a homogenous mixture.
• waste material consists of an aqueous slurry or sludge comprising particulate mineral material, for instance clay, shale, sand, grit, metal oxides etc admixed with water.
• the waste material such as mine tailings can be conveniently disposed of in an underground mine to form backfill.
• backfill waste comprises a high proportion of coarse large sized particles together with other smaller sized particles and is pumped into the mine as slurry where it is allowed to dewater leaving the sedimented solids in place.
• flocculants it is common practice to use flocculants to assist this process by flocculating the fine material to increase the rate of sedimentation.
• the coarse material will normally sediment at a faster rate than the flocculated fines, resulting in a heterogeneous deposit of coarse and fine solids.
• waste solids are separated from solids that contains mineral values in an aqueous process.
• the aqueous suspension of waste solids often contain clays and other minerals, and are usually referred to as tailings. These solids are often concentrated by a flocculation process in a thickener to give a higher density underflow and to recover some of the process water. It is usual to pump the underflow to a surface holding area, often referred to as a tailings pit or dam. Once deposited at this surface holding area, water will continue to be released from the aqueous suspension resulting in further concentration of the solids over a period of time. Once a sufficient volume of water has been collected this is usually pumped back to the mineral processing plant.
• the tailings dam is often of limited size in order to minimise the impact on the environment.
• providing larger dams can be expensive due to the high costs of earth moving and the building of containment walls.
• These dams tend to have a gently sloping bottom which allows any water released from the solids to collect in one area and which can then be pumped back to the plant.
• a problem that frequently occurs is when fine particles of solids are carried away with the run-off water, thus contaminating the water and having a detrimental impact on subsequent uses of the water.
• the bauxite is digested in an aqueous alkaline liquor to form sodium aluminate which is separated from the insoluble residue.
• This residue consists of both sand, and fine particles of mainly ferric oxide.
• the aqueous suspension of the latter is known as red mud.
• the sand (coarse waste) is separated from the red mud.
• the supernatant liquor is further processed to recover aluminate.
• the red mud is then washed in a plurality of sequential washing stages, in which the red mud is contacted by a wash liquor and is then flocculated by addition of a flocculating agent.
• the red mud slurry is thickened as much as possible and then disposed of. Thickening in the context of this specification means that the solids content of the red mud is increased.
• the final thickening stage may comprise settlement of flocculated slurry only, or sometimes, includes a filtration step. Alternatively or additionally, the mud may be subjected to prolonged settlement in a lagoon. In any case, this final thickening stage is limited by the requirement to pump the thickened aqueous suspension to the disposal area.
• the mud can be disposed of and/or subjected to further drying for subsequent disposal on a mud stacking area.
• the mud should have a high solids content and, when stacked, should not flow but should be relatively rigid in order that the stacking angle should be as high as possible so that the stack takes up as little area as possible for a given volume.
• the requirement for high solids content conflicts with the requirement for the material to remain pumpable as a fluid, so that even though it may be possible to produce a mud having the desired high solids content for stacking, this may render the mud unpumpable.
• the sand fraction removed from the residue is also washed and transferred to the disposal area for separate dewatering and disposal.
• EP-A-388108 describes adding a water-absorbent, water-insoluble polymer to a material comprising an aqueous liquid with dispersed particulate solids, such as red mud, prior to pumping and then pumping the material, allowing the material to stand and then allowing it to rigidify and become a stackable solid.
• the polymer absorbs the aqueous liquid of the slurry which aids the binding of the particulate solids and thus solidification of the material.
• this process has the disadvantage that it requires high doses of absorbent polymer in order to achieve adequate solidification. In order to achieve a sufficiently rigidified material it is often necessary to use doses as high as 10 to 20 kilograms per tonne of mud.
• WO-A-96/05146 describes a process of stacking an aqueous slurry of particulate solids which comprises admixing an emulsion of a water-soluble polymer dispersed in a continuous oil phase with the slurry. Preference is given to diluting the emulsion polymer with a diluent, and which is preferably in a hydrocarbon liquid or gas and which will not invert the emulsion. Therefore it is a requirement of the process that the polymer is not added in to the slurry as an aqueous solution.
• WO-A-0192167 describes a process where a material comprising a suspension of particulate solids is pumped as a fluid and then allowed to stand and rigidify.
• the rigidification is achieved by introducing into the suspension particles of a water soluble polymer which has an intrinsic viscosity of at least 3 dl/g.
• This treatment enables the material to retain its fluidity was being pumped, but upon standing causes the material to rigidify.
• This process has the benefit that the concentrated solids can be easily stacked, which minimises the area of land required for disposal.
• the process also has the advantage over the use of cross linked water absorbent polymers in that water from the suspension is released rather than being absorbed and retained by the polymer.
• an objective of the present invention is to find a more suitable method for treating coarse and/or fine particulate waste material from mineral sands, alumina or other mineral processing operations in order to provide better release of liquor and a more effective means of disposing of the concentrated solids.
• an objective of the present invention is to find a more suitable method for treating coarse and/or fine particulate waste material from mineral sands, alumina or other mineral processing operations in order to provide better release of liquor and a more effective means of disposing of the concentrated solids.
• there is a need to improve the dewatering of suspensions of waste solids that have been transferred as a fluid to a settling area for disposal and provide improvements in the clarity of run-off water.
• aqueous liquid contains dispersed particulate solids with a bimodal distribution of particle sizes and following treatment with an effective amount of aqueous solution of a water soluble polymer, on standing, rigidifies without significant segregation of the coarse and fine fractions of particulate solids.
• aqueous solution of water-soluble polymer allows it to retain sufficient fluidity during transfer and then once the material is allowed to stand it will form a solid mass strong enough to support subsequent layers of rigidified material.
• the addition of the aqueous solution of polymer to the material does not cause instant rigidification or substantially any settling of the solids prior to standing.
• the conduit is any convenient means for transferring the material to the deposition area and may for instance be a pipe or a trench. The material remains fluid and pumpable during the transfer stage until the material is allowed to stand.
• the process of the invention is part of the mineral processing operation in which an aqueous suspension of waste solids is optionally flocculated in a vessel to form a supernatant layer comprising an aqueous liquor and an underflow layer comprising thickened solids which form the material.
• the supernatant layer will be separated from the under flow in the vessel and typically recycled or subjected to further processing.
• the aqueous suspension of waste solids or optionally, the thickened underflow is transferred, usually by pumping, to a deposition area, which may for instance be a tailings dam or lagoon.
• the material may consist of only mainly fine particles, or a mixture of fine and coarse particles.
• additional coarse particles may be combined with the aqueous suspension at any convenient point prior to discharge at the deposition area.
• the aqueous polymer solution may be added to the material in an effective amount at any convenient point, typically during transfer. In some cases the aqueous suspension may be transferred first to a holding vessel before being transferred to the deposition area.
• Suitable doses of polymer range from 10 grams to 10,000 grams per tonne of material solids. Generally the appropriate dose can vary according to the particular material and material solids content. Preferred doses are in the range 30 to 3,000 grams per tonne, while more preferred doses are in the range of from 60 to 200 or 400 grams per tonne.
• the material particles are usually inorganic and/or usually a mineral.
• the material may be derived from or contain filter cake, tailings, thickener underflows, or unthickened plant waste streams, for instance other mineral tailings or slimes, including phosphate, diamond, gold slimes, mineral sands, tails from zinc, lead, copper, silver, uranium, nickel, iron ore processing, coalt or red mud.
• the material may be solids settled from the final thickener or wash stage of a mineral processing operation.
• the material desirably results from a mineral processing operation.
• the material comprises tailings.
• the fine tailings or other material which is pumped may have a solids content in the range 10% to 80% by weight.
• the slurries are often in the range 20% to 70% by weight, for instance 45% to 65% by weight.
• the sizes of particles in a typical sample of the fine tailings are substantially all less than 25 microns, for instance about 95% by weight of material is particles less than 20 microns and about 75% is less than 10 microns.
• the coarse tailings are substantially greater than 100 microns, for instance about 85% is greater than 100 microns but generally less than 10,000 microns.
• the fine tailings and coarse tailings may be present or combined together in any convenient ratio provided that material remains pumpable.
• the dispersed particulate solids may have a bimodal distribution of particle sizes.
• this bimodal distribution may comprise a fine fraction and a coarse fraction, in which the fine fraction peak is substantially less than 25 microns and the coarse fraction peak is substantially greater than 75 microns.
• the material is relatively concentrated and homogenous. It may also be desirable to combine the addition of the polymer solution with other additives. For instance the flow properties of the material through a conduit may be facilitated by including a dispersant. Typically where a dispersant is included it would be included in conventional amounts. However, we have found that surprisingly the presence of dispersants or other additives does not impair the rigidification of the material on standing. It may also be desirable to pre-treat the material with either an inorganic or organic coagulant to pre-coagulate the fine material to aid its retention in the rigidified solids.
• the polymer solution is added directly to the aforementioned material.
• the polymer solution may consist wholly or partially of water-soluble polymer.
• the polymer solution may comprise a blend of cross-linked polymer and water soluble polymer, provided sufficient of the polymer is in solution or behaves as though it is in solution to bring about rigidification on standing.
• This may be a physical blend of swellable polymer and soluble polymer or alternatively is a lightly cross-linked polymer for instance as described in EP202780.
• the polymeric particles may comprise some cross-linked polymer it is essential to the present invention that a significant amount of water soluble polymer is present.
• the polymeric particles comprise some swellable polymer it is desirable that at least 80% of the polymer is water-soluble.
• the aqueous solution of polymer comprises polymer which is wholly or at least substantially water soluble.
• the water soluble polymer may be branched by the presence of branching agent, for instance as described in WO-A-9829604, for instance in claim 12 , or alternatively the water soluble polymer is substantially linear.
• the water soluble polymer is of moderate to high molecular weight. Desirably it will have an intrinsic viscosity of at least 3 dl/g (measured in 1 M NaCl at 25° C.) and generally at least 5 or 6 dl/g, although the polymer may be of significantly high molecular weight and exhibit an intrinsic viscosity of 25 dl/g or 30 dl/g or even higher. Preferably the polymer will have an intrinsic viscosity in the range of 8 dl/g to 25 dl/g, more preferably 11 dl/g or 12 dl/g to 18 dl/g or 20 dl/g.
• the water soluble polymer may be a natural polymer, for instance polysaccharides such as starch, guar gum or dextran, or a semi-natural polymer such as carboxymethyl cellulose or hydroxyethyl cellulose.
• the polymer is synthetic and preferably it is formed from an ethylenically unsaturated water-soluble monomer or blend of monomers.
• the water soluble polymer may be cationic, non-ionic, amphoteric, or anionic.
• the polymers may be formed from any suitable water-soluble monomers. Typically the water soluble monomers have a solubility in water of at least 5 g/100 cc at 25° C.
• anionic polymers are formed from monomers selected from ethylenically unsaturated carboxylic acid and sulphonic acid monomers, preferably selected from (meth)acrylic acid, allyl sulphonic acid and 2-acrylamido-2-methyl propane sulphonic acid (AMPS), and their salts, optionally in combination with non-ionic co-monomers, preferably selected from (meth)acrylamide, hydroxy alkyl esters of (meth)acrylic acid and N-vinyl pyrrolidone.
• monomers selected from ethylenically unsaturated carboxylic acid and sulphonic acid monomers preferably selected from (meth)acrylic acid, allyl sulphonic acid and 2-acrylamido-2-methyl propane sulphonic acid (AMPS), and their salts, optionally in combination with non-ionic co-monomers, preferably selected from (meth)acrylamide, hydroxy alkyl esters of (meth)acrylic acid and N-vinyl pyrrol
• Preferred non-ionic polymers are formed from ethylenically unsaturated monomers selected from (meth)acrylamide, hydroxy alkyl esters of (meth) acrylic acid and N-vinyl pyrrolidone.
• Preferred cationic polymers are formed from ethylenically unsaturated monomers selected from dimethyl amino ethyl(meth)acrylate-methyl chloride, (DMAEA.MeCl) quat, diallyl dimethyl ammonium chloride (DADMAC), trimethyl amino propyl(meth)acrylamide chloride (ATPAC) optionally in combination with non-ionic co-monomers, preferably selected from (meth)acrylamide, hydroxy alkyl esters of (meth)acrylic acid and N-vinyl pyrrolidone.
• DAEA.MeCl diallyl dimethyl ammonium chloride
• ATPAC trimethyl amino propyl(meth)acrylamide chloride
• an aqueous solution of an anionic, cationic or non-ionic polymer may be added to the above mentioned material first, followed by a second dose of either a similar or different water soluble polymer of any type.
• the water soluble polymer may be formed by any suitable polymerisation process.
• the polymers may be prepared for instance as gel polymers by solution polymerisation, water-in-oil suspension polymerisation or by water-in-oil emulsion polymerisation.
• the initiators are generally introduced into the monomer solution.
• a thermal initiator system may be included.
• a thermal initiator would include any suitable initiator compound that releases radicals at an elevated temperature, for instance azo compounds, such as azo-bis-isobutyronitrile.
• the temperature during polymerisation should rise to at least 70° C. but preferably below 95° C.
• polymerisation may be effected by irradiation (ultra violet light, microwave energy, heat etc.) optionally also using suitable radiation initiators.
• Such polymer gels may be prepared by suitable polymerisation techniques as described above, for instance by irradiation.
• the gels may be chopped to an appropriate size as required and then on application mixed with the material as partially hydrated water soluble polymer particles.
• the polymers may be produced as beads by suspension polymerisation or as a water-in-oil emulsion or dispersion by water-in-oil emulsion polymerisation, for example according to a process defined by EP-A-150933, EP-A-102760 or EP-A126528.
• the water soluble polymer may be provided as a dispersion in an aqueous medium.
• This may for instance be a dispersion of polymer particles of at least 20 microns in an aqueous medium containing an equilibrating agent as given in EP-A-170394.
• This may for example also include aqueous dispersions of polymer particles prepared by the polymerisation of aqueous monomers in the presence of an aqueous medium containing dissolved low IV polymers such as poly diallyl dimethyl ammonium chloride and optionally other dissolved materials for instance electrolyte and/or multi-hydroxy compounds e.g. polyalkylene glycols, as given in WO-A-9831749 or WO-A-9831748.
• the aqueous solution of water-soluble polymer is typically obtained by dissolving the polymer in water or by diluting a more concentrated solution of the polymer.
• solid particulate polymer for instance in the form of powder or beads, is dispersed in water and allowed to dissolve with agitation. This may be achieved using conventional make up equipment.
• the polymer solution can be prepared using the Auto Jet Wet (trademark) supplied by Ciba Specialty Chemicals.
• the polymer may be supplied in the form of a reverse phase emulsion or dispersion which can then be inverted into water.
• the aqueous polymer solution may be added in any suitable concentration. It may be desirable to employ a relatively concentrated solution, for instance up to 10% or more based on weight of polymer in order to minimise the amount of water introduced into the material. Usually though it will be desirable to add the polymer solution at a lower concentration to minimise problems resulting from the high viscosity of the polymer solution and to facilitate distribution of the polymer throughout the material.
• the polymer solution can be added at a relatively dilute concentration, for instance as low as 0.01% by weight of polymer. Typically the polymer solution will normally be used at a concentration between 0.05 and 5% by weight of polymer. Preferably the polymer concentration will be the range 0.1% to 2 or 3%.
• the concentration will range from 0.25% to about 1 or 1.5%.
• the material can typically be treated at any suitable point after flocculation in the thickener but before the material is allowed to stand.
• a suitable and effective rigidifying amount of the water-soluble polymer solution can be mixed with the material prior to a pumping stage. In this way the polymer solution can be distributed throughout the material. Alternatively, the polymer solution can be introduced and mixed with the material during a pumping stage or subsequently. The most effective point of addition will depend upon the substrate and the distance from the thickener to the deposition area.
• conduit is relatively short any may be advantageous to dose the polymer solution close to where the material flows from the thickener.
• the deposition area is significantly remote from the thickener in may be desirable to introduce the polymer solution closer to the outlet. In some instances in may be convenient to introduce the polymer solution into the material as it exits the outlet.
• the effective rigidifying amount of the water-soluble polymer solution will normally be added during or after the mixing of the different waste streams into a homogeneous slurry.
• the material will be pumped as a fluid to an outlet at the deposition area and the material allowed to flow over the surface of rigidified material.
• the material is allowed to stand and rigidify and therefore forming a stack of rigidified material. This process may be repeated several times to form a stack that comprises several layers of rigidified material.
• the formation of stacks of rigidified material has the advantage that less area is required for disposal.
• the rheological characteristics of the material as it flows through the conduit to the deposition area is important, since any significant reduction in flow characteristics could seriously impair the efficiency of the process. It is important that there is no significant settling of the solids as this could result in a blockage, which may mean that the plant has to be closed to allow the blockage to be cleared. In addition it is important that there is no significant reduction in flow characteristics, since this could drastically impair the pumpability on the material. Such a deleterious effect could result in significantly increased energy costs as pumping becomes harder and the likelihood of increased wear on the pumping equipment.
• the rheological characteristics of the material as it rigidifies is important, since once the material is allowed to stand it is important that flow is minimised and that solidification of the material proceeds rapidly. If the material is too fluid then it will not form an effective stack and there is also a risk that it will contaminate water released from the material. It is also necessary that the rigidified material is sufficiently strong to remain intact and withstand the weight of subsequent layers of rigidified material being applied to it.
• the process of the invention will achieve a heaped disposal geometry and will co-immobilise the fine and course fractions of the solids in the material and also allowing any released water to have a higher driving force to separate it from the material by virtue of hydraulic gravity drainage.
• the heaped geometry appears to give a higher downward compaction pressure on underlying solids which seems to be responsible for enhancing the rate of dewatering. We find that this geometry results in a higher volume of waste per surface area, which is both environmentally and economically beneficial.
• a preferred feature of the present invention is the release of aqueous liquor that often occurs during the rigidification step.
• the material is dewatered during rigidification to release liquor containing significantly less solids.
• the liquor can then be returned to the process thus reducing the volume of imported water required and therefore it is important that the liquor is clear and substantially free of contaminants, especially migrating particulate fines.
• the liquor may for instance be recycled to the thickener from which the material was separated as an underflow.
• the liquor can be recycled to the spirals or other processes within the same plant.
• the aqueous polymer solution is applied to the material in a similar manner as described above.
• the polymer solution is applied in an effective dewatering amount and in the same way as a first aspect of the invention it is important that the fluidity of the material is retained during transfer.
• the material is transferred to a settling area, which can for instance be a tailings dam or a lagoon.
• the dewatering step must proceed as quickly as possible such that the solids are allowed to concentrate and aqueous liquor is released. It is important that the liquor is of high clarity and not contaminated by solids, particularly fines, which would impair further processing.
• a suspension of solids is flocculated in a vessel to form a supernatant layer comprising an aqueous liquor and an underflow layer comprising thickened solids, which forms the material.
• the underflow-suspension flows from the vessel, is optionally combined with additional coarse particulate material, and in which the material is then pumped to a settling area where it is allowed to dewater.
• the aqueous polymer solution is mixed into the material after flocculating the suspension and before the material is allowed to rigidify and dewater.
• the aqueous polymer solution may comprise any of the polymers and be used in a similar manner as that described above.
• Sample C from example 1 was tested according to the procedures and using the tailings slurry detailed in example 1 in conjunction with some additives which may be added to the slurry for other purposes.
• TABLE 6 Sample Additive X organic coagulant - poly DADMAC Y inorganic coagulant - poly aluminium chloride Z organic dispersant - sodium polyacrylate
• Product 1 is an inverse emulsion containing a 80/20 sodium acrylate/acrylamide copolymer.
• Product 1 was inverted into water to provide an aqueous solution containing 0.35% active polymer.
• the product was evaluated on a combination of fine and coarse tailings from a mineral sands operation according to the methods outlined in Example 1 above.
• Fine solids fraction thickener underflow @ 27.7% wt/wt
• Coarse solids fraction cyclone rejects @ 96.4% wt/wt
• the blend of coarse and fine solids were diluted with water to a target solids of 43-47% w/wt.
• Product 2A is an gel product consisting of a 30/70 sodium acrylatelacrylamide copolymer.
• Product 2A was dissolved into water to provide an aqueous solution containing 0.25% product as supplied.
• the polymer was evaluated on a combined fine and coarse tailings from a coal preparation operation at a dosage of 740 gpt.
• the total solids content of the combined tails was approximately 19% wt/wt and approximately 1.4:1 fines/coarse ratio.
• FIG. 1 shows that for the untreated material, a high degree of segregation in the compacted solids has occurred with the majority of the coarse particles only present in the bottom section of the sample.
• FIG. 2 shows that for the material treated with 740 gpt of Polymer 2A, the particle size distributions in both the top and the bottom sections are very similar, and only minimal segregation has occurred during compaction.
• Product 2A was evaluated according to the procedures detailed in example 10 on a combined fine and coarse tailings from a gold CIL/CIP processing operation at a dosage of 240 gpt.
• the total solids content of the combined tails was approximately 53% wt/wt with approximately 2:1 fines/coarse ratio.
• FIG. 3 shows a high degree of segregation of the coarse solids to the bottom section for the untreated material where as for the material treated with Polymer 2A,
• FIG. 4 shows that the top and bottom sections contain similar amounts of both coarse and fine particles.
• Product 2B is an inverse emulsion containing a 30/70 sodium acrylate/acrylamide copolymer.
• Product 2B was inverted into water to provide an aqueous solution containing 1.0% product as supplied.
• the polymer was evaluated on a combined fine and coarse tailings from a mineral sands operation.
• the total solids content of the combined tails was 53% wt/wt with a fines/coarse ratio of approximately 1:5.
• the tails from the Mineral Sands process is pumped uphill out of the lagoon-covered mining area to a raised tailings disposal area.
• the low viscosity of the waste stream together with the high flow rates means that solids are deposited over a great distance, and a long way from the discharge point. Scouring by the tailings stream also creates deep channelling in the disposal area.
• the fluidity of the flow endangers the operation of the mine since at maximum flows, the tails can flow back down into the mining area, swamping the lagoon and interfering with mining efficiency.
• FIG. 5 and FIG. 6 show the discharge of the mineral sands tailings without and with treatment.
• the tails are highly mobile and there is no deposition of solids at the point of discharge.
• FIG. 6 shows stacking of the treated tailings underneath the discharge point and the liberation of clean water in the foreground.
• Product 2B is an inverse emulsion containing a 30/70 sodium acrylate/acrylamide copolymer as used in Example 12 above.
• Product 3 is a solution grade, sodium polyacrylate homopolymer.
• Product 2B was inverted into water to provide an aqueous solution containing 1.0% product as supplied.
• Product 3 was used as supplied with no further dilution necessary.
• the polymers were evaluated on a combined fine and coarse tailings from a mineral sands operation. The solids of the combined tails was 67% wt/wt with a fines/coarse ratio of approximately 1:7.
• the mining operation is mobile and follows the line of the ore body.
• the combined waste material is pumped to a series of pits that are filled sequentially and re-vegetated afterwards. It is desirable for the mining company to operate in as small a footprint as possible at any one time. Faster dewatering rates would allow the rehabilitation process to be started earlier. Additional drainage water could be returned to the process plant for improved efficiency's and reduced imported water costs.
• FIGS. 9, 10 and 11 show the slump angle at discharge into the dam for untreated tails, and tails treated with 513 gpt and 1050 gpt respectively.
• FIGS. 12 and 13 show the discharge characteristics and the dam surface respectively.

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• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)
• Treatment Of Sludge (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)

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