GB2134403A - Filtering - Google Patents

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Publication number
GB2134403A
GB2134403A GB08302834A GB8302834A GB2134403A GB 2134403 A GB2134403 A GB 2134403A GB 08302834 A GB08302834 A GB 08302834A GB 8302834 A GB8302834 A GB 8302834A GB 2134403 A GB2134403 A GB 2134403A
Authority
GB
United Kingdom
Prior art keywords
lime
slurry
filtration
added
filtration process
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Withdrawn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
GB08302834A
Other versions
GB8302834D0 (en
Inventor
Robert Hanson
John Harp
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.)
Edwards and Jones Ltd
Original Assignee
Edwards and Jones Ltd
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 Edwards and Jones Ltd filed Critical Edwards and Jones Ltd
Priority to GB08302834A priority Critical patent/GB2134403A/en
Publication of GB8302834D0 publication Critical patent/GB8302834D0/en
Publication of GB2134403A publication Critical patent/GB2134403A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • 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
    • B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
    • B03B1/00—Conditioning for facilitating separation by altering physical properties of the matter to be treated
    • B03B1/04—Conditioning for facilitating separation by altering physical properties of the matter to be treated by additives
    • 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
    • B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
    • B03B9/00—General arrangement of separating plant, e.g. flow sheets
    • B03B9/005—General arrangement of separating plant, e.g. flow sheets specially adapted for coal

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Filtration Of Liquid (AREA)
  • Treatment Of Sludge (AREA)

Abstract

A filtration process includes the steps of adding lime (Ca(OH)2 or CaO) to a slurry to be filtered such as coal tailings, prior to delivering the slurry to a filter press. Lime is added as a solid or liquid suspension in an amount up to 1% of the dry solids content of the slurry.

Description

SPECIFICATION Improvements in or relating to a filtration process The present invention concerns improvements in or relating to a filtration process, especially but not exclusively a filtration process involving the use of a plate filter press.
In a plate filter press a slurry to be filtered is fed to a compartment defined by two plates which are clamped together and lined with a filter cloth. Filtrate escapes through the cloth and the residue retained in the cavity forms a filter cake which, after the filtration process is completed is removed from the cavity on separation of the plates.
It has been found that in this and in other filtration processes the efficiency of filtration is not as high at the beginning of the operation as it is towards the end of the operation. At the beginning of the operation filtration is provided only by the filter medium, for example the filter cloth, whereas at the end of the operation additional filtration is provided by the filter cake retained bythe medium. This means that during initial filtration fine material may escape with the filtrate.
It is an object of the present invention to obviate or mitigate this disadvantage.
According to the present invention there is provided a filtration process including the steps of adding lime (Ca(OH)2) to a slurry to be filtered prior to presenting the slurry to a filter medium.
Preferably the slurry and added lime are agitated prior to filtration.
Preferably the amount of lime added to the slurry is up to 1% by weight Ca(OH)2 to dry solids in the slurry to be filtered. Advantageously the percentage of lime added is 0.5% or lower.
The lime may be added in solid or liquid form.
Preferably the filtering operation is carried out in a plate filter press.
An embodiment of the present invention will now be described by way of example only.
Prior to supplying slurry to the filter chambers of a plate filter press 0.5% by weight Ca(OH)2 to dry solids in the slurry of hydrated lime (or equivalent in quick lime) is added in liquid or dry form and is thoroughly mixed with the slurry by agitation in a mixing chamber fitted with an agitator.
The slurry with added lime is then fed to the filter press which operates in a normal manner.
The addition of lime, especially when utilised in the de-watering of coal tailings has been found to lead to following advantages: a) Reduced filtration times, hence increased outputs (between 50 and 100% increases have been obtained); b) Improved solids retention within the filter cake, that is retention of the fine solids during the initial stages of the filtration operation; c) improved handleabilityofthefiltercake; d) improved release of filter cake from the filter media, this leading to more automatic discharge and hence reduced discharge times and further increased output.
It will be realised that the process involved requires the expenditure of very little additional outlay as the filter press remains unmodified.
Various modifications can be carried out without departing from the scope of the invention, for example the filtration process can be carried out on filtering equipment other than plate filter presses.
Additionally, methods of addition of the lime other than addition into a mixing chamber fitted with an agitator can be employed, for example the lime can be dosed directly into pipe line feeding slurry to the filtering apparatus or can be added to bulk slurry storage tanks or thickeners.
Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to whether or not particular emphasis has been placed thereon.
CLAIMS (Filed on 15.12.83) 1. A filtration process including the steps of adding lime to a slurry to be filtered prior to presenting the slurry to a filter medium.
2. A filtration process as claimed in claim 1, in which the slurry and added lime are agitated prior to filtration.
3. A filtration process as claimed in claim 1 or claim 2, in which the lime is quick lime (CaO) or slaked lime (Ca(OH)2).
4. A filtration process as claimed in claim 3, in which the amount of lime added to the slurry is up to 1% by weight Ca(OH)2 to dry solids in the slurry to be filtered.
5. A filtration process as claimed in claim 4, in which the percentage of lime added is 0.5% or lower.
6. A filtration process as claimed in any one of the preceding claims, in which the lime is added in solid form.
7. A filtration process as claimed in any one of claims 1 to 4, in which the lime is added in liquid form.
8. A filtration process as claimed in any one of the preceding claims, in which the filtering operation is carried out in a plate filter press.
9. Afiltration process as claimed in claim 7, in which the slurry is coal tailings.
10. Afiltration process substantially as hereinbefore described.
11. A process for the dewatering of coal tailings in a plate filter press comprising adding lime to the tailings, prior to the introduction thereof into the press.
12. Any novel subject matter or combination including novel subject matter herein described, whether or not within the scope of or relating to the same invention as any of the preceding claims.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    SPECIFICATION Improvements in or relating to a filtration process The present invention concerns improvements in or relating to a filtration process, especially but not exclusively a filtration process involving the use of a plate filter press.
    In a plate filter press a slurry to be filtered is fed to a compartment defined by two plates which are clamped together and lined with a filter cloth. Filtrate escapes through the cloth and the residue retained in the cavity forms a filter cake which, after the filtration process is completed is removed from the cavity on separation of the plates.
    It has been found that in this and in other filtration processes the efficiency of filtration is not as high at the beginning of the operation as it is towards the end of the operation. At the beginning of the operation filtration is provided only by the filter medium, for example the filter cloth, whereas at the end of the operation additional filtration is provided by the filter cake retained bythe medium. This means that during initial filtration fine material may escape with the filtrate.
    It is an object of the present invention to obviate or mitigate this disadvantage.
    According to the present invention there is provided a filtration process including the steps of adding lime (Ca(OH)2) to a slurry to be filtered prior to presenting the slurry to a filter medium.
    Preferably the slurry and added lime are agitated prior to filtration.
    Preferably the amount of lime added to the slurry is up to 1% by weight Ca(OH)2 to dry solids in the slurry to be filtered. Advantageously the percentage of lime added is 0.5% or lower.
    The lime may be added in solid or liquid form.
    Preferably the filtering operation is carried out in a plate filter press.
    An embodiment of the present invention will now be described by way of example only.
    Prior to supplying slurry to the filter chambers of a plate filter press 0.5% by weight Ca(OH)2 to dry solids in the slurry of hydrated lime (or equivalent in quick lime) is added in liquid or dry form and is thoroughly mixed with the slurry by agitation in a mixing chamber fitted with an agitator.
    The slurry with added lime is then fed to the filter press which operates in a normal manner.
    The addition of lime, especially when utilised in the de-watering of coal tailings has been found to lead to following advantages: a) Reduced filtration times, hence increased outputs (between 50 and 100% increases have been obtained); b) Improved solids retention within the filter cake, that is retention of the fine solids during the initial stages of the filtration operation;
    c) improved handleabilityofthefiltercake; d) improved release of filter cake from the filter media, this leading to more automatic discharge and hence reduced discharge times and further increased output.
    It will be realised that the process involved requires the expenditure of very little additional outlay as the filter press remains unmodified.
    Various modifications can be carried out without departing from the scope of the invention, for example the filtration process can be carried out on filtering equipment other than plate filter presses.
    Additionally, methods of addition of the lime other than addition into a mixing chamber fitted with an agitator can be employed, for example the lime can be dosed directly into pipe line feeding slurry to the filtering apparatus or can be added to bulk slurry storage tanks or thickeners.
    Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to whether or not particular emphasis has been placed thereon.
    CLAIMS (Filed on 15.12.83) 1. A filtration process including the steps of adding lime to a slurry to be filtered prior to presenting the slurry to a filter medium.
  2. 2. A filtration process as claimed in claim 1, in which the slurry and added lime are agitated prior to filtration.
  3. 3. A filtration process as claimed in claim 1 or claim 2, in which the lime is quick lime (CaO) or slaked lime (Ca(OH)2).
  4. 4. A filtration process as claimed in claim 3, in which the amount of lime added to the slurry is up to 1% by weight Ca(OH)2 to dry solids in the slurry to be filtered.
  5. 5. A filtration process as claimed in claim 4, in which the percentage of lime added is 0.5% or lower.
  6. 6. A filtration process as claimed in any one of the preceding claims, in which the lime is added in solid form.
  7. 7. A filtration process as claimed in any one of claims 1 to 4, in which the lime is added in liquid form.
  8. 8. A filtration process as claimed in any one of the preceding claims, in which the filtering operation is carried out in a plate filter press.
  9. 9. Afiltration process as claimed in claim 7, in which the slurry is coal tailings.
  10. 10. Afiltration process substantially as hereinbefore described.
  11. 11. A process for the dewatering of coal tailings in a plate filter press comprising adding lime to the tailings, prior to the introduction thereof into the press.
  12. 12. Any novel subject matter or combination including novel subject matter herein described, whether or not within the scope of or relating to the same invention as any of the preceding claims.
GB08302834A 1983-02-02 1983-02-02 Filtering Withdrawn GB2134403A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08302834A GB2134403A (en) 1983-02-02 1983-02-02 Filtering

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08302834A GB2134403A (en) 1983-02-02 1983-02-02 Filtering

Publications (2)

Publication Number Publication Date
GB8302834D0 GB8302834D0 (en) 1983-03-09
GB2134403A true GB2134403A (en) 1984-08-15

Family

ID=10537331

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08302834A Withdrawn GB2134403A (en) 1983-02-02 1983-02-02 Filtering

Country Status (1)

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GB (1) GB2134403A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110203999A1 (en) * 2010-02-19 2011-08-25 Simpson Daniel J Dewatering of drilling mud using a filter press

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB380239A (en) * 1930-09-22 1932-09-15 Dorr Co Inc Improvements in slurry filtration
GB425976A (en) * 1933-06-23 1935-03-25 Gutehoffnungshuette Oberhausen A method of drying sludges
GB2016942A (en) * 1977-11-09 1979-10-03 Kuebler H A method of and an apparatus for expressing liquid from clarifying sludges
GB2024250A (en) * 1978-06-23 1980-01-09 Broken Hill Pty Co Ltd Treatment of aqueous slurries of particulate material
EP0040903A2 (en) * 1980-05-27 1981-12-02 Dow Corning Corporation Dewatering fine coal slurries using two types of organopolysiloxanes
EP0040906A2 (en) * 1980-05-27 1981-12-02 Dow Corning Corporation Dewatering fine coal slurries using organopolysiloxanes

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB380239A (en) * 1930-09-22 1932-09-15 Dorr Co Inc Improvements in slurry filtration
GB425976A (en) * 1933-06-23 1935-03-25 Gutehoffnungshuette Oberhausen A method of drying sludges
GB2016942A (en) * 1977-11-09 1979-10-03 Kuebler H A method of and an apparatus for expressing liquid from clarifying sludges
GB2024250A (en) * 1978-06-23 1980-01-09 Broken Hill Pty Co Ltd Treatment of aqueous slurries of particulate material
EP0040903A2 (en) * 1980-05-27 1981-12-02 Dow Corning Corporation Dewatering fine coal slurries using two types of organopolysiloxanes
EP0040906A2 (en) * 1980-05-27 1981-12-02 Dow Corning Corporation Dewatering fine coal slurries using organopolysiloxanes

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110203999A1 (en) * 2010-02-19 2011-08-25 Simpson Daniel J Dewatering of drilling mud using a filter press
US9138668B2 (en) * 2010-02-19 2015-09-22 Daniel J. Simpson Dewatering of drilling mud using a filter press

Also Published As

Publication number Publication date
GB8302834D0 (en) 1983-03-09

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