WO2014111884A1 - Traitement de produits de queue fins - Google Patents

Traitement de produits de queue fins Download PDF

Info

Publication number
WO2014111884A1
WO2014111884A1 PCT/IB2014/058347 IB2014058347W WO2014111884A1 WO 2014111884 A1 WO2014111884 A1 WO 2014111884A1 IB 2014058347 W IB2014058347 W IB 2014058347W WO 2014111884 A1 WO2014111884 A1 WO 2014111884A1
Authority
WO
WIPO (PCT)
Prior art keywords
suspension
polymer
water
shearing
solids
Prior art date
Application number
PCT/IB2014/058347
Other languages
English (en)
Inventor
Angela Beveridge
John Ramsay
Pablo MENDEZ
Original Assignee
Basf Se
Basf Canada Inc.
Basf (China) Company Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Basf Se, Basf Canada Inc., Basf (China) Company Limited filed Critical Basf Se
Priority to CA2892982A priority Critical patent/CA2892982A1/fr
Publication of WO2014111884A1 publication Critical patent/WO2014111884A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
    • C10G1/04—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction
    • C10G1/045—Separation of insoluble materials
    • 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
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
    • C02F11/147—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using organic substances
    • 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
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/15—Treatment of sludge; Devices therefor by de-watering, drying or thickening by treatment with electric, magnetic or electromagnetic fields; by treatment with ultrasonic waves
    • 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
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
    • 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
    • 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
    • C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
    • C02F2103/36—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from the manufacture of organic compounds
    • C02F2103/365—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from the manufacture of organic compounds from petrochemical industry (e.g. refineries)

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 mining and mineral processing operations.
  • the invention is particularly suitable for the treatment of oil sand tailings and especially mature fine tailings (MFT) derived from oil sand tailings.
  • MFT mature fine tailings
  • waste material consists of an aqueous slurry or sludge comprising particulate mineral material, for instance clay, shale, sand, grit, oil sand tailings, 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.
  • the ore is processed to recover the hydrocarbon fraction, and the remainder, including both process material and the gangue, constitutes the tailings that are to be disposed of.
  • the main process material is water
  • the gangue is mostly sand with some silt and clay.
  • the tailings consist of a solid part (sand tailings) and a more or less fluid part (sludge). The most satisfactory place to dispose of these tailings is, of course, in the existing excavated hole in the ground. It turns out, however, that the sand tailings alone from the one cubic foot of ore occupy just about one cubic foot. The amount of sludge is variable, depending on ore quality and process conditions, but average about 0.3 cubic feet. The tailings simply will not fit back into the hole in the ground.
  • waste solids are separated from solids that contain 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 or more usually a tailings pond in the case of oil sands. 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.
  • tailings pond or dam is often of limited size in order to minimise the impact on the environment.
  • providing larger tailings ponds can be expensive due to the high costs of earth moving and the building of containment walls.
  • These ponds 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.
  • a tailings pond may be contained within a retaining structure which may be referred to as a dyke structure.
  • a suitable dyke structure may generally be constructed by placing the sand fraction of the tailings within cells or on beaches. Tailings streams initially discharged into the ponds may have relatively low densities and solids contents, for instance around 0.5 to 10% by weight.
  • MFT matrix fine tailings
  • the composition of mature fine tailings tends to be highly variable.
  • the upper part of the stratum may have a mineral content of about 10% by weight but at the bottom of the stratum the mineral content may be as high as 50% by weight.
  • the variation in the solids content is believed to be as a result of the slow settling of the solids and consolidation occurring over time.
  • the average mineral content of the M FT tends to be of about 30% by weight.
  • the MFT generally comprises a mixture of sand, fines and clay.
  • the sand may refer- red to siliceous particles of a size greater than 44 ⁇ and may be present in the MFT in an amount of up to 15% by weight.
  • the remainder of the mineral content of the MFT tends to be made up of a mixture of clay and fines.
  • the fines refer to mineral particles no greater than 44 ⁇ .
  • the clay may be any material traditionally referred to as clays by virtue of its mineralogy and will generally have a particle size of below 2 ⁇ .
  • the clays tend to be water swelling clays, such as montmorillonites.
  • the clay content may be up to 75% of the solids.
  • composition of MFT may be as a result of the residual hydrocarbon which may be dispersed in the mineral or may segregate into mat layers of hydrocarbon.
  • the MFT in a pond not only has a wide variation of compositions distributed from top to bottom of the pond but there may also be pockets of different compositions at random locations throughout the pond.
  • aqueous suspensions waste solids from mining and mineral processing operations including mining tailings, such as MFT, held in ponds of holding areas may also contain coarse debris.
  • the type and composition of this coarse debris depends on the origin of the suspension In the case of MFT the coarse debris tends to be of different sizes, shapes and chemical compositions.
  • M FT may include coarse debris such as biomass, such as wood or other plant material; petrified matter; solids having a density low enough to float at or near the surface of the pond; glass; plastic; metal; bitumen globules; or mats.
  • the coarse debris found other mining tailings may include similar debris as in the case of MFT, with the exception of bitumen materials and may also include other debris materials such as lumps of ore or other masses depending on the geology of the ore mine, the ore extraction processing technique, or the location of the tailings pond.
  • aqueous suspensions and mining tailings such as MFT
  • a typical chemical treatment employs the addition of chemical flocculating agents to bring about flocculation and be so formed flocculated suspensions can be subjected to dewatering.
  • 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 com- prising 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 as 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 dis- posal.
  • 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.
  • WO2004/060819 describes a process in which material comprising an aqueous liquid with dispersed particulate solids is transferred as a fluid to a deposition area, then allowed to stand and rigidify, and in which rigidification is improved whilst retaining the fluidity of the material during transfer, by combining with the material an effective rigidifying amount of an aqueous solution of a water-soluble polymer. Also described is a process in which dewatering of the particulate solids is achieved.
  • Canadian patent application 2512324 describes a process for the rigidification of a suspension which is or comprises oil sand tailings.
  • the process involves transferring the suspension as a fluid to a deposition area in which an effective rigidifying amount of an aqueous solution of a water-soluble polymer is combined with the suspension during transfer and then allowing the so treated suspension to stand and rigidify.
  • the rigidification is improved whilst retaining the fluidity of the material during transfer.
  • the process was particularly suited to the treatment of tailings as they are produced from the oil sands processing operation.
  • suspensions which contain a very high proportion of fine solids and clays, such as MFT are particularly difficult to dewater and generally require very high doses of chemical treatment aids.
  • step (b) addition of a water-soluble polymer of intrinsic viscosity of at least 3 dl/g to the modified suspension of step (a); (c) dewatering the polymer treated suspension of step (b), in which the kinetic energy stage is a shearing stage and/or application of ultrasonic energy to the suspension, wherein the shearing stage comprises subjecting the suspension to shearing employing a shearing device and in which the shearing device is selected from the group con- sisting of:
  • a shearing device comprising moving elements which rotate, preferably impellers, kneading components, or moving plates;
  • a milling device comprising moving elements
  • mineral particles of particle size below 50 ⁇ we mean solid mineral particles that are not water swelling clays that may generally be referred to as fines. Often these mineral particles may be referred to as silt. Usually these mineral particles have a size of no greater than 44 ⁇ . Typically they will have a size between 2 ⁇ and 44 ⁇ , although their size may be smaller.
  • the mineral origin of the particles often will be silica and/or quartz and/or feldspar.
  • the mineral particles may typically be present in the suspension in an amount of at least 10% by weight of the mineral content. Often the particles may be present in amount of at least 15% for at least 20% by weight of the solids content. In some cases the solids content of the suspension may be made up of up to 50 or 60% by weight.
  • the clay may be any material traditionally referred to as clays by virtue of its mineralogy and will tend to have a particle size of below 2 ⁇ .
  • the clays may tend to be a mixture of clays.
  • the clay component may comprise kaolinite; illite; chlorite; montmorillonites; kaolinite-smectite mixtures; illite-smectite mixtures.
  • the clay content of the suspension would usually be at least 20% of the solids and may be as much as 75% of the solids.
  • the suspension comprises mature fine tailings derived from oil sands tailings.
  • suspensions which contain a high proportion of very small sized mineral particles and clay particles, especially where they have been held in tailings ponds over a considerable time, even many years, such as oil sands deri- ved MFT, exhibit three-dimensional particle network structures based on the clays.
  • These network structures are believed to include clay-clay intra-particle networks and clay-inter-particle network structures which incorporate the fine mineral particles.
  • the inventors believe that these network structures comprise clay particles linked to each other and network structures where clay particles and the fine particles are linked together by clay particles. Further, it is believed that this network structure is responsible for retaining more water than in suspensions of equivalent solids.
  • the electrostatic forces within the clay inter-particle structure may be responsible for the difficulty in achieving adequate water release with conventional doses of chemical treatment aids.
  • applying kinetic energy to the suspension provides a modified suspension which is significantly more conducive to releasing water by chemical treatment.
  • the inventors believe that the action of the kinetic energy on the suspension directly interacts with the clay-clay intra-particle network structures and the clay inter-particle network structures. In fact it is believed that the shear will at least partially breakdown these network structures.
  • kinetic energy we mean that suspension is subjected some energy which is or induces motion within the suspension.
  • the kinetic energy may be ultrasonic energy.
  • the application of ultrasonic energy will induce vibrations which will at least partially break down the network structures.
  • Other forms of kinetic energy may be alternative me- ans for inducing vibrations.
  • One particularly suitable form of kinetic energy is shearing.
  • the kinetic energy stage for instance shearing, may be carried out in a vessel, for instance a shearing vessel, before being transferred to the next step of the process.
  • the kinetic energy stage for instance shearing, may be carried out in line as the suspension is being transferred.
  • any conventional shearing device may be employed as such devices are very well known in the industry and also described in the literature.
  • Industrial scale shear devices for instance shear mixing devices or shear pumps are available from a variety of manufacturers, for instance IKA which manufactures Ultra Turrax high shear devices, for instance the devices in the Ultra Turrax UTL 2000 range; Fluko-high shear mixers; Silverson high shear mixers, for instance Ultramix mixers or In-line mixers; Euromixers; Greaves; Admix Inc which ma- nufactures Rotosolver high shear devices; Charles Ross and Son Company which manufactures Ross high shear mixers; Robbins Myers which manufactures Greerco high shear mixers; Powershear Mixers.
  • Suitable shearing devices generally have moving elements: such as rotating components, for instance impellers; kneeding components; or moving plates.
  • the mixing pumps may also contain static elements such as baffles or plates, for instance containing orifices.
  • the moving elements will tend to move quite rapidly in order to generate shear. In general this will depend upon the mode of action within the shearing chamber and the size of the volume that is being sheared. This may be for instance at least 5 cycles per second (5 s 1 ) or at least 6 s 1 , at least 7 s 1 , or at least 8 s 1 , or at least 9 s 1 and usually at least 10 s 1 , suitably at least 20 s . Typically this may be up to 170 s 1 , up to 200 s 1 or up to 300 s 1 or more.
  • the residence time When the suspension, for instance oil sands derived M FT, is subjected to shearing, the period of shearing may be referred to as the residence time.
  • the residence time in the shearing device may be, for instance at least 1 second. Often it will be at least 5 seconds and sometimes at least 10 seconds. It may be up to 30 seconds or more or it may be up to 15 seconds or up to 20 seconds. In some situations it may be at least 20 seconds, for instance at least 1 min and often may be several hours, for instance up 10 hours or more.
  • the residence time may be at least 5 min, suitably at least 10 min and often at least 30 min. In many cases it may be at least one hour. In some cases the residence time may be up to 8 hours but desirably less than this.
  • the shearing device may even be a milling device.
  • Milling devices include colloid mills, cone mills and rotor mills etc.
  • moving elements for instance cones, screens or plates containing gaps, grooves , slots or orifices which move against other static elements.
  • the moving elements may move instance by rotation. These devices tend to generate a high level of shear stress on liquids and other materials passing through them.
  • the moving elements tend to combine high-speed with a very small shear gap which produces intense friction on the material being processed. The friction and shear that result is commonly referred to as wet milling.
  • the milling device may contain a rotor and a stator, which are both cone shaped and may have one or more stages of fine grooves, gaps, slots or orifices.
  • This stator can be adjusted to obtain the desired gap setting between the rotor and stator.
  • the grooves, gaps, slots or orifices may change direction in each stage to increased turbulence. The moving elements will tend to move quite rapidly in order to generate sufficient shear.
  • This may be for instance at least 5 cycles per second (5 s 1 ), or at least 6 s 1 , at least 7 s 1 , or at least 8 s 1 , or at least 9 s 1 and usually at least 10 s 1 , suitably at least 20 s 1 , typically up to 170 s 1 , up to 200 s- 1 or up to 300 s 1 or more.
  • the suspension may be passed through a static mixer or other static elements which bring about a shearing action, for instance baffles in a pipeline or alternatively a constriction in a pipeline.
  • the inventors have noted that during the application of kinetic energy, for instance by shearing of the suspension, in particular the oil sands derived MFT, a notable reduction in viscosity of the suspension can occur.
  • viscosity may be measured by a controlled stress rheometer, such as a Brookfield RS.
  • Viscosity may be measured at 25°C Generally the viscosity of the modified (for instance sheared) suspension would often be below 90% of the viscosity of the suspension prior to the application of kinetic energy, such as the shearing stage.
  • the viscosity of the modified suspension for instance sheared suspension
  • the viscosity of the modified suspension is no more than 80% of the viscosity of the suspension before the application of kinetic energy, such as shearing and more preferably no more than 70%. More preferably still the modified suspension, for instance sheared suspension, viscosity will be up to 60% and in particular less than 50% of the suspension before the application of kinetic energy, for instance un- sheared suspension.
  • the viscosity of the modified suspension may be as little as 0.001 % of the suspension before the application of kinetic energy, for instance shearing, or even below.
  • the modified suspension, for instance sheared suspension will be at least 0.05% or 0.1 % of the suspension before the application of kinetic energy, for instance un-sheared suspension.
  • the modified suspension, for instance sheared suspension will be at least 1 %, at least 5% or at least 10% of the suspension before the application of kinetic energy, for instance un-sheared suspension.
  • the process of the present invention involves addition of a water-soluble polymer which exhibits an intrinsic viscosity of at least 3 dl/g.
  • the addition of this polymer facilitates the removal of water in the dewatering step.
  • the inventors believe that the availability of water released from the clay-clay intra-particle network structures and clay inter-particle network structures facilitates the integration of the water-soluble polymer throughout the solids of the suspension.
  • the dewatering of the polymer treated suspension may employ any known dewatering method.
  • the dewatering step may involve sedimentation of the polymer treated suspension to produce a settled sediment.
  • Such a process may be carried out in a vessel for example a gravimetric thickener or in a settlement pond.
  • the dewatering process may involve pressure dewatering, for example using a filter press, a belt press or a centrifuge.
  • the dewatering process is a process of rigidification of the solids in the suspension and the dewatering step is part of the rigidification process.
  • the sheared suspension is transferred as a fluid to a deposition area, then allowed to stand and rigidifying, in which the water-soluble polymer is added to the sheared suspension during the transfer of the sheared suspension.
  • Rigidification is a term that refers to a networked structure of particulate solids. Compared with settling or sedimentation, rigidification is faster, produces more recovered water and results in a chemically bonded tailings that occupy a smaller surface area, which is more quickly
  • Rigidified tailings are also less likely to spread laterally after deposition enabling more efficient land use; and would more rapidly form a solid structure in the form of a beach or stack; and have a greater yield stress when deposited, with increased uniformity or homogenity of coarse and fine particles. Further by reason of its heaped geometry as a beach or stack such rigidified material would result in downward compression forces, driving water out of the stack and more rapid release of water, with better clarity.
  • the water-soluble polymer may be added to the modified suspension, for instance sheared suspension, in the form of an aqueous solution.
  • the addition of water-soluble polymer, preferably an aqueous solution of water-soluble polymer allows the modified suspension, for instance sheared suspension, 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 polymer, preferably as an aqueous solution of the polymer, to the sheared suspension does not cause instant rigidifica- tion or substantially any settling of the solids prior to standing.
  • 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 suspension particular the oil sands derived M FT
  • the flow properties of the material through a conduit may be facilitated by including a dispersant.
  • a dis- persant typically where a dis- persant is included it would be included in conventional amounts.
  • the presence of dispersants or other additives does not impair the rigidification of the suspension on standing.
  • 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 preferably as an aqueous solution, is added directly to the aforementioned modified suspension, for instance sheared suspension.
  • 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 par- tides 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 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. It will have an intrinsic viscosity of at least 3 dl/g 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 8dl/g to 25 dl/g, more preferably 1 1 dl/g or 12 dl/g to 18 dl/g or 20 dl/g.
  • Intrinsic viscosity of polymers may be determined by preparing an aqueous solution of the polymer (0.5-1 % w/w) based on the active content of the polymer. 2 g of this 0.5-1 % polymer solution is diluted to 100 ml in a volumetric flask with 50 ml of 2M sodium chloride solution that is buffered to pH 7.0 (using 1.56 g sodium dihydrogen phosphate and 32.26 g disodium hydrogen phosphate per litre of deionised water) and the whole is diluted to the 100 ml mark with deion- ised water. The intrinsic viscosity of the polymers is measured using a Number 1 suspended level viscometer at 25°C in 1 M buffered salt solution.
  • 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 hy- droxyethyl cellulose.
  • the polymer is synthetic and preferably it is formed from an eth- ylenically 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 5g/1 OOcc 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.
  • 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.MeCI) 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.MeCI diallyl dimethyl ammonium chloride
  • ATPAC trimethyl amino propyl (meth) acrylamide chloride
  • non-ionic co-monomers preferably selected from (meth) acrylamide, hydroxy alkyl esters of (meth) acrylic acid and N-vinyl pyrrolidone.
  • 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 pro- cess.
  • 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 pro- cess 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 BASF.
  • 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 add- ed 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%. More preferably the concentration will range from 0.25% to about 1 or 1.5%.
  • a suitable and effective rigidifying amount of the water-soluble polymer preferably as an aque- ous solution, can be mixed with the sheared suspension prior to a pumping stage.
  • the polymer solution can be distributed throughout the sheared suspension.
  • the polymer solution can be introduced and mixed with the sheared suspension during a pumping stage or subsequently.
  • the most effective point of addition will depend upon the substrate and the distance from the kinetic energy stage, for instance shearing stage to the deposition area. If the conduit is relatively short it may be advantageous to dose the polymer solution close to where the modified suspension, for instance sheared suspension, flows from the shearing device.
  • shearing device 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 sheared suspension as it exits the outlet.
  • the polymer treated suspension will be pumped as a fluid to an outlet at the deposition area and the so treated suspension allowed to flow over the surface of rigidified material.
  • the suspension is allowed to stand and rigidify and therefore forming a stack of rigidified mate- rial. This process may be repeated several times to form a stack that comprises several layers of rigidified solids of the suspension.
  • the formation of stacks of rigidified material has the advantage that less area is required for disposal.
  • the rheological characteristics of the polymer treated suspension 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 suspension. 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 suspension as it rigidifies is important, since once the polymer treated suspension is allowed to stand it is important that flow is minimised and that solidi- fication of the polymer treated suspension proceeds rapidly. If the polymer treated suspension 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 suspension. It is also necessary that the rigidified material is sufficiently strong to remain intact and withstand the weight of subsequent layers of rigidified suspension being applied to it.
  • the process of the invention will achieve a heaped disposal geometry and will co- immobilise the fine and any coarse fractions of the solids in the suspension and also allowing any released water to have a higher driving force to separate it from the suspension 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 de- watering. 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 suspension is de- watered 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 mining operation, for instance oil sands operation, from which the suspension originates.
  • the liquor can be recycled to the spirals or other processes within the same plant.
  • clarifying polymers may optionally be added after the thickener to the underflow but before disposal by rigidification. This may enhance the clarity of the water released from the rigidifying stack.
  • the clarifying polymers are typically low molecular weight, polymers.
  • low molecular weight means an average molecular weight ranging from about 10,000 to about 1 ,000,000 g/mol.
  • anionic polymers in the range of about 10,000 to about 500,000 g/mol may be used. These can be anionic, non-ionic or cationic. They can be synthetic or naturally derived, e.g. from starch, gums or cellulose, e.g. carboxymethyl cellulose. Preferably they are anionic, e.g.
  • the amount of clarifying polymer will be determined by the composition of the oil sands tailings but generally about 5 to about 500 g/tonne of dry solids.
  • the amount of clarifying polymer may be about 5 g to about 100 g/tonne of dry solids.
  • the clarifying polymer may be added as a solution and may be added in any suitable concen- tration. 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.
  • the clarifying polymer solution can be added at a relatively dilute concentration, for instance as low as 0.01 % by weight of polymer. Typically the clarifying 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%. More preferably the concentration will range from 0.25% to about 1 or 1.5%.
  • the clarifying polymer may be added before, simultaneously, or after the rigidifying amount of the water-soluble polymer added according to the present invention.
  • the present invention also includes a test method for evaluating suspensions which contain fine mineral particles and clay, especially mature fine tailings derived from oil sands tailings.
  • a further aspect of the invention defines a method of testing a suspension which comprises particulate solids dispersed in an aqueous liquid, said particulate solids comprises clay and mineral particles of size below 50 ⁇ , which method comprises the steps of,
  • step (b) addition of a water-soluble polymer intrinsic viscosity of at least 3 dl/g to the modified suspension of step (a);
  • step (c) transferring the polymer treated suspension of step (b) onto a mesh; and (d) measuring the water drained through the mesh and measuring the angle formed between the base of the solids retained on the mesh and a line drawn between the perimeter of the solids at the highest point in the centre of the solids.
  • the suspension may be in accordance with the suspension already defined herein.
  • the suspension comprises mature fine tailings (MFT) that have been derived from oil sands tailings.
  • MFT mature fine tailings
  • kinetic energy we mean that suspension is subjected some energy which is or induces motion within the suspension.
  • the kinetic energy may be ultrasonic energy.
  • the application of ultrasonic energy will induce vibrations which will at least partially break down the network structures.
  • Other forms of kinetic energy may be alternative means for inducing vibrations.
  • One particularly suitable form of kinetic energy is shearing.
  • the shearing may be carried out by any suitable shearing devices that may be employed in a laboratory.
  • suitable shearing devices may be domestic or laboratory shearing devices, such as those manufactured by Silverson or Moulinex.
  • One particularly suitable shearing device comprises a flat paddle impeller.
  • a sample of the suspension desirably M FT
  • a sample of the suspension may be placed into a beaker or other convenient receptacle, suitably having a circular cross-section.
  • Kinetic energy should then be ap- plied to the suspension, for instance ultrasonic energy or shearing using a shearing device.
  • the shearing member of the shearing device should then be inserted into the suspension.
  • the shearing device comprises a flat paddle impeller it is preferred that the length of the paddle fits substantially across the diameter of the beaker or receptacle. By this we mean that there may be up to 1 , 2, or 3 mm clearance between the wall of the beaker or receptacle and the ends of the flat paddle.
  • the sample should be sheared by operating the shearing device at a rate of at least 200 rpm, preferably at least 300 rpm and more preferably at least 400 rpm, especially at the 450 rpm.
  • rate of shearing There is no upper limit to the rate of shearing but generally this would tend to depend on the type of shearing device and this would tend not to be greater 10,000 rpm or 20,000 rpm.
  • the upper rate of shearing may be no more than 1000 rpm and usually less than this.
  • a desirable rate of shearing when using the flat paddle impeller may be in the range of between 200 and 800 rpm, preferably between 300 and 700 rpm, more preferably between 400 and 600 rpm, especially between 450 and 550 rpm.
  • the duration of the shearing will tend to be at least 1 or 2 seconds and usually at least 5 seconds and in some cases at least 30 seconds or at least 1 min.
  • the period of shearing may be longer than this, for instance up to 30 min or more. Generally the period of shearing would be up to 20 min.
  • the polymer solution will normally be used at a concentration between 0.05 and 5% by weight of polymer.
  • the polymer concentration will be the range 0.1 % to 2 or 3%. More preferably the concentration will range from 0.25% to about 1 or 1.5%.
  • the polymer treated suspension may be transferred to a sealed container and inverted several times, for instance between 2 and 10 inversions, suitably between 3 and 5 inversions.
  • the mesh onto which the polymer treated suspension is applied maybe any suitable mesh which allow water to drain through it and retain the solids on top of it.
  • the mesh may be part of a sieve.
  • the mesh may be made from metal or other material such as plastic.
  • MFT mature fines tailings
  • the sheared suspension is passed along a conduit and an anionic polyacrylamide, consisting of an aqueous solution of a copolymer of acrylamide with sodium acrylate (30/70 on a weight basis) are an intrinsic viscosity of 19 dl/g at a concentration of 0.5%, is introduced into the suspension at a dose of 2000 g/tonne (based on active polymer per dry aqueous sheared suspension).
  • an anionic polyacrylamide consisting of an aqueous solution of a copolymer of acrylamide with sodium acrylate (30/70 on a weight basis) are an intrinsic viscosity of 19 dl/g at a concentration of 0.5%
  • the polymer treated sheared suspension continues to flow along the conduit to an outlet where the polymer treated sheared suspension is allowed to flow on to a sand bed.
  • the so treated sheared suspension very quickly dewaters and forms a heap of rigidified, dewatered MFT solids. As the MFT dewaters substantially clear aqueous fluid flows from the heap.
  • a sample (100 ml.) of an aqueous suspension comprising mature fines tailings (MFT) derived from oil sands is fed into a laboratory shearing device.
  • the shearing device comprises a flat bottomed flask of diameter of 10 cm containing a flat paddle stirrer with a 2 mm clearance from the wall of the flask which flat paddle stirrer is connected to a motor.
  • the flat paddle stirrer is rotated at 500 rpm for 30 seconds thereby shearing the suspension comprising MFT.
  • the sheared suspension of M FT is then treated with an aqueous solution of a copolymer of acrylamide with sodium acrylate (30/70 on a weight basis) are an intrinsic viscosity of 19 dl/g at a concentration of 0.5% at a dose of 1900 g/tonne (based on active polymer per dry aqueous sheared suspension).
  • the polymer treated MFT suspension is then poured on to a metal mesh where it instantly de- waters and forms a rigidified mass of solids on the surface of the mesh. Water which drains through the mesh is collected and measured. The yield stress of the deposited material is peri- odically measured to establish its increasing rigidity with time.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Water Supply & Treatment (AREA)
  • Environmental & Geological Engineering (AREA)
  • Hydrology & Water Resources (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Wood Science & Technology (AREA)
  • Separation Of Suspended Particles By Flocculating Agents (AREA)

Abstract

La présente invention concerne un procédé de déshydratation d'une suspension comportant des solides particulaires dispersés dans un liquide aqueux. Les solides particulaires comportent de l'argile et des particules minérales de taille inférieure à 50 μπι. Le procédé comprend les étapes suivantes : (a) le traitement de la suspension dans une étape d'énergie cinétique pour produire une suspension modifiée ; (b) l'addition d'un polymère hydrosoluble ayant une viscosité intrinsèque d'au moins 3 dl/g à la suspension modifiée de l'étape (a) ; (c) la déshydratation de la suspension traitée de l'étape (b), l'étape d'énergie cinétique étant une étape de cisaillement et/ou d'application d'énergie ultrasonore à la suspension, l'étape de cisaillement comprenant le traitement de la suspension par cisaillement au moyen d'un dispositif de cisaillement. Le procédé est particulièrement approprié pour la déshydratation de produits de queue fins dérivés de produits de queue de sables bitumineux.
PCT/IB2014/058347 2013-01-18 2014-01-17 Traitement de produits de queue fins WO2014111884A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA2892982A CA2892982A1 (fr) 2013-01-18 2014-01-17 Traitement de produits de queue fins

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201361753958P 2013-01-18 2013-01-18
US61/753,958 2013-01-18
EP13151880 2013-01-18
EP13151880.5 2013-01-18

Publications (1)

Publication Number Publication Date
WO2014111884A1 true WO2014111884A1 (fr) 2014-07-24

Family

ID=47598701

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2014/058347 WO2014111884A1 (fr) 2013-01-18 2014-01-17 Traitement de produits de queue fins

Country Status (2)

Country Link
CA (1) CA2892982A1 (fr)
WO (1) WO2014111884A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10513451B2 (en) 2017-03-23 2019-12-24 Baker Hughes, A Ge Company, Llc Treatment of mature fine tailings in produced water by flocculation and dewatering

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1102627A (zh) * 1994-04-16 1995-05-17 黑龙江大学聚合物科学与技术试验研究基地 聚合物eor工程采出水中残存聚合物分离方法及药剂
WO2001005712A1 (fr) * 1999-07-19 2001-01-25 Ciba Specialty Chemicals Water Treatments Limited Procede de floculation de suspensions
CN102532409A (zh) * 2011-12-15 2012-07-04 东营市诺尔化工有限责任公司 网状阳离子聚丙烯酰胺制备方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1102627A (zh) * 1994-04-16 1995-05-17 黑龙江大学聚合物科学与技术试验研究基地 聚合物eor工程采出水中残存聚合物分离方法及药剂
WO2001005712A1 (fr) * 1999-07-19 2001-01-25 Ciba Specialty Chemicals Water Treatments Limited Procede de floculation de suspensions
CN102532409A (zh) * 2011-12-15 2012-07-04 东营市诺尔化工有限责任公司 网状阳离子聚丙烯酰胺制备方法

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10513451B2 (en) 2017-03-23 2019-12-24 Baker Hughes, A Ge Company, Llc Treatment of mature fine tailings in produced water by flocculation and dewatering

Also Published As

Publication number Publication date
CA2892982A1 (fr) 2014-07-24

Similar Documents

Publication Publication Date Title
CA2651863C (fr) Suppression de poussiere dans un materiau mineral particulaire deshydrate
CA2651440C (fr) Traitement de suspensions aqueuses
US7901583B2 (en) Treatment of aqueous suspensions
CA2512324C (fr) Traitement de suspensions aqueuses
AU2016254609A1 (en) Separation of suspensions of solids employing water soluble polymer and a chemical agent
WO2015083069A1 (fr) Processus de déshydratation de résidus minéraux par le traitement de ces résidus avec une solution comprenant au moins un polymère et au moins un sel
WO2015173741A1 (fr) Procédé de déshydratation de résidus minéraux par traitement de ces résidus avec au mois un tensioactif et au moins un polymère
WO2015173728A1 (fr) Procédé de déshydratation de résidus minéraux par traitement desdits résidus avec au moins deux polymères différents de viscosités intrinsèques différentes
CA2897663C (fr) Procede de deshydratation de residus mineraux par le traitement de ces residus avec au moins un polymere anionique et au moins un polymere cationique
WO2014111884A1 (fr) Traitement de produits de queue fins
WO2014111886A1 (fr) Procédé d'égouttage mécanique de refus de crible minéraux par traitement des refus de crible au moyen d'au moins une solution de polymère dilué et d'au moins un polymère concentré
CA2897660C (fr) Procede de deshydratation de residus mineraux par traitement des residus avec des particules polymeres
CA2892983C (fr) Traitement de refus de crible fins
AU2013204568C1 (en) Treatment of Aqueous Suspensions
CA3077551A1 (fr) Deshydratation amelioree de residus miniers au moyen d`un pretraitement a l`aluminosilicate
AU2007100377B4 (en) Treatment of aqueous suspensions

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 14740487

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2892982

Country of ref document: CA

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 14740487

Country of ref document: EP

Kind code of ref document: A1