EP0601023A1 - Deshydratation de boues minerales - Google Patents

Deshydratation de boues minerales

Info

Publication number
EP0601023A1
EP0601023A1 EP92918418A EP92918418A EP0601023A1 EP 0601023 A1 EP0601023 A1 EP 0601023A1 EP 92918418 A EP92918418 A EP 92918418A EP 92918418 A EP92918418 A EP 92918418A EP 0601023 A1 EP0601023 A1 EP 0601023A1
Authority
EP
European Patent Office
Prior art keywords
coal
dewatering
slurry
flocculant
filter cake
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP92918418A
Other languages
German (de)
English (en)
Other versions
EP0601023A4 (en
Inventor
Mark Edward Keeney
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Unilever PLC
Original Assignee
Unilever PLC
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 Unilever PLC filed Critical Unilever PLC
Publication of EP0601023A1 publication Critical patent/EP0601023A1/fr
Publication of EP0601023A4 publication Critical patent/EP0601023A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D37/00—Processes of filtration
    • B01D37/03—Processes of filtration using flocculating agents

Definitions

  • This invention relates to improved dewatering methods and agents for use in vacuum filtration operations in mineral and coal processing.
  • the invention is generally applicable to the dewatering of slurries including those encountered in the processing of minerals such as alumina, as well as coal, but it is of particular interest in the dewatering of fine coal and accordingly will be described in detail with particular reference to the latter application.
  • Vacuum filtration is commonly used in industrial processes to remove water from slurries.
  • Vacuum disc and drum filters are widely used, as well as vacuum belt filters.
  • Coal processing particularly the treatment of metallurgical coal, usually incorporates washing steps as part of the beneficiation scheme.
  • the coal-cleaning process produces coal with a broad range of particle sizes.
  • Coarse coal ie., >600 micron
  • fine coal are treated differently to dewater effectively.
  • Water is usually removed from coarse coal by screen drainage or centrifugation and from fine coal (ie., flotation concentrates or refuse) by centrifugation or vacuum filtration.
  • thermal drying of fine coal is employed as a necessary step to achieve target moistures.
  • the moisture levels in the cleaned coal can vary quite widely. Typical moisture levels in coarse coal range from 2-12%, while fine coal moistures can range from 15-30%.
  • Coal processing plants often have considerable trouble meeting target moisture levels in the product coal they sell. As a result of new mining methods employed in long- wall operations, the proportion of fine coal reporting to the washing & preparation plants has increased significantly. Fine coal is much more difficult and costly to dewater than coarse coal.
  • One method often employed by coal prep plants to achieve moisture specifications is to blend high-moisture fine coal with low-moisture coarse coal in proportions necessary to just meet target moisture.
  • Vacuum filtration is the most commonly used means of mechanical treatment to dewater fine coal. Fine coal, in slurry form, reports to the filtration operation where the water is removed. Vacuum disc and drum filters are the principal type used by the coal industry to filter fine coal, although increasing interest is being shown in vacuum belt filters. To assist in the efficient operation of vacuum filters, reagents are often added to the feed slurry.
  • anionic flocculants usually high molecular weight acrylamide/acrylate co-polymers
  • cationic flocculants usually low molecular weight polyamines
  • coal is an organic material. Coals vary widely in bulk/surface composition, depending upon a multiplicity of factors such as location of the deposit, rank and mineral (inorganic) matter, degree of weathering, internal structure/porosity, etc. Therefore, depending upon the specific coal treated, dewatering aid performance can be expected to vary widely since both the adsorption (a surface chemical property) and absorption (a bulk chemical property) characteristics of coals with respect to drainage aid interaction will vary widely.
  • a method of dewatering an aqueous coal or mineral slurry comprising adding a flocculant to the slurry, subsequently adding a dewatering aid, and filtering the slurry by means of vacuum filtration to obtain a filter cake and a filtrate, characterised in that the dewatering aid is added at just prior to formation of the filter cake during the filtration step.
  • the dewatering aid is a salt such as a sodium salt of a fatty acid including fatty acids derived from tall oil.
  • the fatty acid may have from 8 to 20 carbon atoms.
  • sodium oleate is particularly preferred.
  • the dewatering aid may also be a potassium or ammonium salt of a fatty acid.
  • the dewatering aid may also comprise either a salt of a sulphonic acid such as dodecyl benzene sulphonic acid, an ethoxylated alcohol or an unsaponified fatty acid.
  • a sulphonic acid such as dodecyl benzene sulphonic acid, an ethoxylated alcohol or an unsaponified fatty acid.
  • the flocculant may be added to the coal slurry prior to the filtration step in a ratio in the range from 10 to 100 and preferably 20 to 50 gms per tonne of mineral or coal contained in the slurry.
  • the dewatering aid may be added to the slurry in a ratio in the range from .02 to 1.5 and preferably 0.5 to 1.5 kg per tonne of mineral or coal.
  • a two-stage process is provided involving use of anionic flocculants in place of cationic flocculants, in combination with application of the dewatering aid at a particular stage of the process, to provide a greatly improved and much more cost-effective process for dewatering slurries than has hitherto been considered feasible.
  • Figure 1 is a graph of filter cake moisture content versus cationic flocculant dosage at a fixed drying time and applied vacuum.
  • Figure 2 is a graph of filter cake form time and apparent applied vacuum against cationic flocculant dosage rate
  • Figure 3 is a graph of filter cake moisture content and form time versus applied vacuum at a fixed dosage rate of cationic flocculant
  • Figure 4 is a graph of filter cake moisture content versus dosage rate of dewatering aid where the dewatering aid is added at different locations in the filtration step
  • Figure 5 is a graph of filter cake form time versus anionic flocculant dosage rate for two types of anionic flocculant.
  • Figure 6 is a graph of filter cake moisture content versus anionic flocculant dosage rate for two types of anionic flocculant
  • Figure 7 is a graph of filter cake moisture content versus dosage rate of dewatering aid showing the effect of incorporating the dewatering aid at various locations in the filtration step
  • Figure 8 is a graph of filter cake moisture content versus dewatering aid dosage rate for both an anionic flocculated filter cake and a cationic flocculated filter cake
  • Figure 9 is a graph of filter cake moisture content versus anionic flocculant dosage rate with and without the addition of a dewatering aid.
  • Figure 1 shows the time required to achieve filter cake formation and the apparent vacuum of the system (at 80 kPa applied vacuum) as a function of coagulant addition.
  • an equivalent dosage of 250 g/tonne of the cationic flocculant was required as an addition to the test-rig slurry.
  • Figure 2 shows the residual filter cake moistures achieved in the lab test rig as a function of cationic flocculant addition. Use of the cationic flocculant at the dosage rate determined above (for proper form time/apparent vacuum) results in a residual moisture level of 22-23%.
  • Figure 3 shows the variation in filter-cake moisture and formation time as a function of the applied vacuum (at a fixed dosage of cationic flocculant) .
  • Figure 4 shows that at the preferred dose rate 0.50 kg/tonne the most effective methods of reagent application are to ensure that the reagent is applied to the Delkor filter (from a trough or spray system) at or close to the point of formation of the filter cake. Moisture reduction of approximately 3 to 5% (22-23% to 18-19%) can be expected if the reagent is properly applied.
  • Testwork was conducted on samples of fine-coal taken from the plant prior to being treated with the cationic reagent, using both of the liquid anionic flocculants (i.e., acrylate/acrylamide copolymers) currently used by Bellambi in other process operations.
  • the results, given in Figure 5, show that by replacing the cationic flocculant with an anionic flocculant the filter cake formation time can be dramatically reduced (from 60 sec to 20 sec) using less than one-tenth of the amount of reagent (15 g/t anionic flocculant vs 250 g/t cationic flocculant) .
  • the cost per weight unit is identical, the saving is substantial.
  • the application of the drainage aid reagent to the vacuum filter as a filter-cake spray at or around the point of cake formation on the filter belt/disc enables an anionic flocculant to be substituted for a cationic flocculant for filter feed thickening.
  • This two-stage approach to fine-coal dewatering has been found to completely eliminate problems associated with process control if an anionic flocculant is used to thicken the filter feed slurry.
  • the reagent spray has been found to ensure that filter cake permeability during the dewatering phase of filtration (i.e., once air begins penetration of the filter cake) is maintained regardless of any slight overdosing of the anionic flocculant due to process swings. This permits an anionic flocculant to be substituted for a cationic flocculant with enormous process savings.
  • Figure 9 shows the impact on final product cake moisture using an anionic flocculant pretreatment step prior to filtration with and without the aid of the applied reagent.
  • High product cake moistures are encountered where the flocculated pretreatment is too high and the corresponding curve shows the rise in moisture after this phenomenon occurs (i.e., around 20 g/T flocculant dose).
  • the problems encountered with flocculant overdosing are corrected by way of a synergism with the reagent addition.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Separation Of Suspended Particles By Flocculating Agents (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
  • Treatment Of Sludge (AREA)

Abstract

Cette méthode concerne la déshydratation des boues minérales et notamment celles de charbon fin. Elle consiste à ajouter à la boue un floculant anionique puis un adjuvant de déshydratation pendant ou juste avant la formation d'un gâteau de filtre-presse lors d'une phase de filtration. Cette méthode montre que la surcharge par un floculant anionique est évitable si on utilise ce dernier en combinaison avec un adjuvant de déshydratation.
EP9292918418A 1991-08-20 1992-08-19 Dewatering slurries. Withdrawn EP0601023A4 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AUPK785591 1991-08-20
AU7855/91 1991-08-20
PCT/AU1992/000437 WO1993003812A1 (fr) 1991-08-20 1992-08-19 Deshydratation de boues minerales

Publications (2)

Publication Number Publication Date
EP0601023A1 true EP0601023A1 (fr) 1994-06-15
EP0601023A4 EP0601023A4 (en) 1994-09-28

Family

ID=3775635

Family Applications (1)

Application Number Title Priority Date Filing Date
EP9292918418A Withdrawn EP0601023A4 (en) 1991-08-20 1992-08-19 Dewatering slurries.

Country Status (5)

Country Link
EP (1) EP0601023A4 (fr)
JP (1) JPH06509975A (fr)
CA (1) CA2115153A1 (fr)
WO (1) WO1993003812A1 (fr)
ZA (1) ZA926247B (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3199218B1 (fr) 2009-09-15 2019-11-06 Suncor Energy Inc. Procédé de séchage de résidus fins des sables bitumineux
CA3050234C (fr) 2009-09-15 2022-11-08 Suncor Energy Inc. Techniques de floculation et de deshydratation de residus fins
AU2009354586A1 (en) 2009-10-30 2012-05-24 Suncor Energy Inc. Depositing and farming methods for drying oil sand mature fine tailings
US11459257B1 (en) * 2017-05-12 2022-10-04 Eco Environmental, LLC Method of treating a liquid with nanobubbles

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4132630A (en) * 1978-04-03 1979-01-02 Gulf Research & Development Company Method for separating solids from coal liquids
US4290897A (en) * 1980-05-27 1981-09-22 Dow Corning Corporation Dewatering fine coal slurries using two types of organopolysiloxanes
CA1156535A (fr) * 1980-10-29 1983-11-08 Dieter Frank Hydroxybenzylamines, utilisees comme agents de deshydratation
IN172903B (fr) * 1990-05-08 1994-01-01 Lever Hindustan Ltd

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
No further relevant documents disclosed *
See also references of WO9303812A1 *

Also Published As

Publication number Publication date
JPH06509975A (ja) 1994-11-10
WO1993003812A1 (fr) 1993-03-04
ZA926247B (en) 1993-04-22
EP0601023A4 (en) 1994-09-28
CA2115153A1 (fr) 1993-03-04

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