GB2433215A

GB2433215A - Vehicle mounted mixer

Info

Publication number: GB2433215A
Application number: GB0604249A
Authority: GB
Inventors: Geoffrey Kevin Ellison; Francis Alan Hay
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-03
Filing date: 2006-03-03
Publication date: 2007-06-20
Anticipated expiration: 2026-03-03
Also published as: GB2433215B; GB0604249D0

Abstract

A method of mixing a sealant or sealing material (such as bentonite clay) on site at a borehole (such as in a landfill site) to be used to seal a portion of the borehole (such as an upper portion of the annular space surrounding a tubular borehole lining tube or casing), comprises transporting to the borehole site a mixing container or vessel 7 mounted on a displacement arm of an excavator, digger or the like vehicle having a lifting or articulated arm, adding liquid (such as water) to the sealing material and mixing such together using a mixing device powered from the excavator or other vehicle (such as by means of the hydraulic system thereof) and then delivering, the mixed sealing material to the required space of the borehole using the vehicle (such as by pouring the sealing mixture from the mixing vessel with the aid of the vehicle's lifting arm or pumping such therefrom using suitable pump means powered from the excavator or other vehicle's power source or by directing such from a sluice in the bottom of the vessel). A further embodiment is directed at an apparatus in which sealing material may be mixed having a coupling which connects to the articulated arm of an excavator, digger or other vehicle. The mixing device is hydraulically driven by motor 16 via couplings to the hydraulic of the vehicle and includes a pouring lip 9 and internal graduated scale.

Description

IMPROVED METHOD AND APPARATUS FOR SEALING BOREHOLES

The present invention relates to an improved method and apparatus for sealing boreholes.

On completion of drilling a borehole in a landfill site, for example, a tubular liner casing is inserted in the borehole. An upper portion of the casing, say the top three meters, is a continuous surface tube whilst the portion therebeneath is apertured to allow gas to pass into the tube for extraction.

Normally the space surrounding the apertured portion is packed with gravel.

A seal is required to be provided between the continuous surface upper portion of the casing and the surrounding strata to prevent the release of gas upwardly externally of the casing and prevent the downward flow of rainwater.

The normal sealing material is bentonite, a widely used clay material.

The bentonite is supplied in either pellet or powder form. Pellets are sometimes added to the annulus between the casing and the strata where they become hydrated by the moisture in the surrounding strata. This technique does not always enable the bentonite to become fully hydrated resulting in an ineffective seal. When powder is used, it is premixed by hand or by an electric mixer in a manually transported container, such as a wheelbarrow or bucket, before being poured into the annulus. This is a relatively slow and labour intensive process. The bentonite is thixotropic and thus may set or stiffen if not mixed promptly and handled efficiently.

The present invention is concerned with an apparatus which can achieve provision of a more reliable bentonite seal by the controlled mixing and delivery of hydrated bentonite using an excavator and by also removing or minimizing the need for manual handling.

A method of mixing a sealing material, such as bentonite clay, on site at a borehole, such as in a landfill site, to seal a portion of the borehole, such as

I

an upper portion of the annular space surrounding a tubular borehole lining tube or casing, comprises transporting to the borehole site a mixing container or vessel mounted on a displacement arm of an excavator, digger or the like vehicle with a lifting or articulated arm, adding liquid, such as water, to the sealing material and mixing such together using a mixing device powered from the excavator or other vehicle, such as by means of the hydraulic system thereof, then delivering, as desired, the mixed sealing material to the borehole using the vehicle, such as by pouring the sealing mixture from the mixing vessel with the aid of the vehicle's lifting arm or pumping such therefrom using suitable pump means powered from the excavator or other vehicle's power source or by directing such from a sluice in the bottom of the vessel.

Also according to the invention there is provided an apparatus for sealing boreholes comprising a mixing vessel in which sealing material may be mixed and having coupling means connectable to the quick-fit or like coupling of the articulated displacement arm of an excavator, digger or other vehicle having a lifting or articulated arm, and a hydraulically or other powered mixing device carried by said mixing vessel for mixing materials therein and readily connectable to quick-fit or like couplings of the hydraulic system or other system (e.g. pneumatic or electric system) of the vehicle.

Preferably means will be provided to facilitate pouring (such as a lip) or discharge of the mixed material, such as a pump preferably with tubular delivery means or a discharge sluice.

Preferably the interior of the vessel has a graduated scale to facilitate the proportioning of the mixing materials.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which:-Fig 1 is a schematic view of an example of a borehole sealed in accordance with the method of the present invention using the apparatus of the present invention; Fig 2 is a perspective view of the front of a mixing apparatus according to the invention attached to the end of the articulated arm of an excavator! digger; Fig 3 is a perspective view of the apparatus of Fig 2 from the rear and showing the coupling device of the vessel connected to the quick-fit coupling device of the articulated arm of the excavator the back-hoe bucket thererof having been removed; Fig 4 is an enlarged partial perspective view from above and showing the mixing device mounted on the top of the mixing vessel and showing the hydraulic connection of the hydraulic circuit of the excavator hydraulic system connected thereto; Fig 5 is a rear perspective view from the opposite side to that of Fig 4 showing the hydraulic hoses!pipes running from the articulated arm to the mixing device.

In the borehole schematically illustrated in Fig 1, the a circular cross-section borehole I has previously been drilled and then a tubular steel casing or liner 2 inserted in the borehole and this liner 2 has in its lower region a plurality of apertures or holes 3 extending through the wall to enable the passage of gas from the landfill site into the interior of the liner 2 to enable withdrawal by suitable pumping means (not shown). The apertures 3 are not in the upper region (e.g. not in the top three meters) of the casing as such has to be sealed to prevent the downflow of water and to prevent the upward escape of gas. In the annular space surrounding the lower portion of the casing gravel 4 is packed and is such as to enable gas to pass through such and through the holes 3 into the interior of the casing. On top of this gravel 4 a layer of particulate or dry bentonite 5 is applied to seal such and then a hydrated or wet mix of bentonite clay 6 has been delivered and filled there from the apparatus 7 according to the present invention and in accordance with the method of the present invention to seal the upper surrounding annular space as required.

The apparatus 7 according to the preferred embodiment of the invention is shown in Figures 2-5 and comprises a free standing, open-topped generally cylindrical vessel 8 of horizontal circular cross-section but with upwardly diverging tapering walls and having a pouring lip 9 at its upper edge on one side. On the opposite external side the vessel 7 has coupling means 11 provided for ready connection/disconnection to/from the quick-coupling device such as are commonplace on the free ends of the articulated arm 12 of an excavator or digger 13 and to which normally a back-hoe (not shown) is connected and also to which back-hoe hydraulic pipes 14, 15 are also connected to work the back-hoe. In the illustrated embodiment the back-hoe has been removed and the hydraulic pipes 14, 15 disconnected therefrom but connected via quick coupling means to a hydraulic mixing device 16 which has a long shaft 17 extending down into the container on which blades or elongate paddles (not shown) are mounted extending along the length of the shaft 17 to form a mixing device for material 18 within the vessel. The mixer device 16 is mounted on a plate 19 with the rotor extending therethrough and which is welded to the top rim of the vessel 8. The vessel 8 and plate 19 are normally made of steel.

The inside of the vessel 8 has a graduated scale or scales (not shown) to enable accurate measurement of the ingredients, and as mentioned, the lip 9 is provided for pouring the material therefrom such as the hydrated bentonite 18.

Alternatively, although not shown, material may be pumped from the vessel by means of an hydraulically operated pump (or other) which may be provided in the base of the vessel 8.

The mixer 16 has a stirrer as mentioned which is operated hydraulically by a motor attached to the mixer. As mentioned the power for the mixer is taken by means of "quick-fit" connectors to the hydraulic pipes 14, 15 and system of the excavator. Instead of hydraulic power of course pneumatic or electric power may be used.

In use and in the method according to the invention, water is added to the required level in the vessel and then bentonite powder is added in a sufficient amount to achieve the required mix for the particular use and then the mixing device is energised by activation of the supplementary hydraulic circuit on the excavator normally for the backOhoe attachment and agitation continues until the mixture is homogonous and the bentonite is fully hydrated. The mixing vessel is then positioned by using the articulated arm of the excavator adjacent the borehole and the mixture poured (or pumped) into the borehole.

The process requires no manual handling and as the bentonite is added rapidly to the borehole it prevents problems of solidification that can occur when using a thixotropic material.

It will be appreciated that the apparatus of the invention enables operation at remote locations and the materials for the proceeding operation may be carried by the excavator or other vehicle such as possibly even within the vessel itself or elsewhere.

By using the hydraulic circuit of the excavator for the mixing, there is considerable labour-saving as also for the lifting and pouring (or pumping) the use of the excavator facilities and provides considerable advantages.

It is to be appreciated that other materials such as cement might even be mixed with the apparatus of the invention and according to the method of the present invention for use in boreholes or on landfill sites.

Claims

CLAIMS

1. A method of mixing a sealant or sealing material (such as bentonite clay) on site at a borehole (such as in a landfill site) to be used to seal a portion of the borehole (such as an upper portion of the annular space surrounding a tubular borehole lining tube or casing), comprises transporting to the borehole site a mixing container or vessel mounted on a displacement arm of an excavator, digger or the like vehicle having a lifting or articulated arm, adding liquid (such as water) to the sealing material and mixing such together using a mixing device powered from the excavator or other vehicle (such as by means of the hydraulic system thereof) and then delivering the mixed sealing material to the required space of the borehole using the vehicle (such as by pouring the sealing mixture from the mixing vessel with the aid of the vehicle's lifting arm or pumping such therefrom using suitable pump means powered from the excavator or other vehicle's power source or by directing such from a sluice in the bottom of the vessel).

2. An apparatus for sealing boreholes comprising a mixing vessel in which sealing material may be mixed and having coupling means connectable to the quick-fit or like coupling of the articulated displacement arm of an excavator, digger or other vehicle having a lifting or articulated arm, and a hydraulically or other powered mixing device carried by said mixing vessel for mixing materials therein and readily connectable to quick-fit or like couplings of the hydraulic system or other system (e.g. pneumatic or electric system) of the vehicle.

3. Apparatus as claimed in claim 2, in which discharge means are provided to facilitate pouring (such as a lip) or discharge of the mixed material, such as by means of a pump, preferably with tubular delivery means or a discharge sluice.

4. Apparatus as claimed in claim 2 or 3, in which the interior of the vessel has a graduated scale to facilitate the proportioning of the mixing materials.

5. Apparatus substantially as herein described with reference to the accompanying drawings.

6. A borehole site whenever sealed according to the method of claim 1.