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Title:
SLAG EXPANSION TESTING MACHINE AND RELATED METHOD
Document Type and Number:
WIPO Patent Application WO/2012/104653
Kind Code:
A1
Abstract:
An apparatus for expansion testing of slag samples comprises: at least one heating chamber, in which water is heatable to produce steam for delivery to a testing unit containing a slag sample; and water level measurement means for measuring the level of water within the at least one heating chamber; wherein the water level measurement means is provided at a sheltered location within the at least one heating chamber.

Inventors:
JONES, Nick (191 Wickersley Road, Rotherham, South Yorkshire S60 4JP, GB)
BAGGALEY, Craig (37 Norstead Crescent, BramleyRotherham, South Yorkshire S66 2SH, GB)
WALTON, Mark (Manor Farm, Dalton Lane Dalton Parva,Rotherham, South Yorkshire S65 3QQ, GB)
GAYNOR, Ian (68 Rosemary Road, WickersleyRotherham, South Yorkshire S66 2DE, GB)
LILLEKER, Geoff (74 Cemetery Road, HemingfieldBarnsley, South Yorkshire S73 0QD, GB)
Application Number:
GB2012/050237
Publication Date:
August 09, 2012
Filing Date:
February 03, 2012
Export Citation:
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Assignee:
HARSCO METALS GROUP LIMITED (Harsco House, 299 Kingston RoadLeatherhead, Surrey KT22 7SG, GB)
JONES, Nick (191 Wickersley Road, Rotherham, South Yorkshire S60 4JP, GB)
BAGGALEY, Craig (37 Norstead Crescent, BramleyRotherham, South Yorkshire S66 2SH, GB)
WALTON, Mark (Manor Farm, Dalton Lane Dalton Parva,Rotherham, South Yorkshire S65 3QQ, GB)
GAYNOR, Ian (68 Rosemary Road, WickersleyRotherham, South Yorkshire S66 2DE, GB)
LILLEKER, Geoff (74 Cemetery Road, HemingfieldBarnsley, South Yorkshire S73 0QD, GB)
International Classes:
G01N33/42; G01N25/16
Other References:
NICK JONES MULTISERV INTERNATIONAL: "Session 3,Stream 3C,Slag pavement Workshop: The European Standard Test Method for the Expansion of Steel Slag", THE 2007 AUSTRALASIAN (IRON & STEEL) SLAG ASSOCIATION'S CONFERENCE: SUSTAINABILITY & SLAG, 4 May 2007 (2007-05-04), XP002674506, Retrieved from the Internet: URL:http://www.asa-inc.org.au/conference/papers.htm [retrieved on 2012-04-23]
DATABASE WPI Week 200707 Thomson Scientific, London, GB; AN 2007-069143 XP002674507, & KR 2006 0070043 A (RES INST IND SCI&TECHNOLOGY) 23 June 2006 (2006-06-23)
DATABASE WPI Week 201102 Thomson Scientific, London, GB; AN 2010-N86055 XP002674508, & KR 2010 0117962 A (HYUNDAI STEEL CO) 4 November 2010 (2010-11-04)
DATABASE WPI Week 198836 Thomson Scientific, London, GB; AN 1988-254507 XP002674509, & JP 63 186148 A (DAIDO TOKUSHUKO KK) 1 August 1988 (1988-08-01)
DATABASE WPI Week 200438 Thomson Scientific, London, GB; AN 2004-405373 XP002674510, & JP 2004 144690 A (DAIDO TOKUSHUKO KK) 20 May 2004 (2004-05-20)
DATABASE WPI Week 199537 Thomson Scientific, London, GB; AN 1995-277761 XP002674511, & JP 7 174757 A (KAWASAKI STEEL CORP) 14 July 1995 (1995-07-14)
None
Attorney, Agent or Firm:
AVIDITY IP et al. (Merlin House, Falconry CourtBaker's Lane,Epping, Essex CM16 5DQ, GB)
Download PDF:
Claims:
CLAIMS

1. An apparatus for expansion testing of slag samples comprising : at least one heating chamber, in which water is heatable to produce steam for delivery to a testing unit containing a slag sample; and water level measurement means for measuring the level of water within the at least one heating chamber; wherein the water level measurement means is provided at a sheltered location within the at least one heating chamber.

2. An apparatus according to claim 1, wherein the sheltered location is provided by an alcove, a recess or a cavity.

3. An apparatus according to claim 1, wherein the sheltered location is provided by a barrier, a screen or a baffle.

4. An apparatus according to claim 1, claim 2 or claim 3 further comprising at least one testing unit for receiving a slag sample, each of the at least one testing units having at least one inlet through which steam produced in the at least one heating chamber can pass.

5. An apparatus according to claim 4, wherein the at least one inlet is provided by an array of holes.

6. An apparatus according to claim 4 or claim 5, wherein the testing unit is encased in a heatable jacket.

7. An apparatus according to claim 4, claim 5 or claim 6, wherein each of the at least one testing units is associated with an individual heating chamber.

8. An apparatus according to claim 7, wherein each of the at least one testing units is securable above an individual heating chamber.

9. An apparatus according to claim 8, wherein the testing unit is securable by interengagement between the testing unit or a portion thereof, and a housing in which the heating chamber is located .

10. An apparatus according to claim 9, wherein the interengagement is provided by a flange and at least one holding projection suitable to receive the flange.

11. An apparatus according to claim 10, wherein the at least one holding projection is provided by or on the housing.

12. An apparatus according to claim 10 or claim 11, wherein there are three holding projections.

13. An apparatus according to claim 10, claim 11 or claim 12, wherein the testing unit comprises a base, which comprises the at least one inlet and provides the flange.

14. An apparatus according to any of claims 10 to 13, wherein the flange comprises at least one gap positioned around the perimeter thereof.

15. An apparatus according to claim 14, wherein the flange comprises three gaps equally spaced around the perimeter thereof.

16. An apparatus according to claim 14 or claim 15, wherein the or each gap is defined by a pair of opposed flange portions.

17. An apparatus according to claim 16, wherein one of the opposed flange portions comprises a chamfered portion.

18. An apparatus according to any preceding claim, wherein the water level measurement means comprises a probe.

19. An apparatus according to claim 18, wherein the probe comprises a plurality of rods.

20. An apparatus according to claim 19, wherein the probe comprises three rods.

21. An apparatus according to any one of claims 9 to 20, wherein the housing comprises a major aperture, which provides an opening to the heating chamber.

22. An apparatus according to claim 21, wherein the major aperture is bound by a groove suitable for receiving a sealing ring.

23. An apparatus according to any preceding claim, further comprising at least one expansion measurement means for measuring the expansion of the slag sample.

24. An apparatus according to claim 23, wherein the at least one expansion measurement means comprises a potentiometer.

25. An apparatus according to claim 23 or claim 24, further comprising a means for supporting the at least one expansion measurement means.

26. An apparatus according to claim 25, wherein the means for supporting the at least one expansion measurement means comprises a frame mountable on a part of the apparatus.

27. An apparatus according to claim 26, wherein the frame comprises a clamping mechanism for receiving and holding, in use, a portion of the expansion measurement means.

28. A method for expansion testing of a slag sample comprising : placing a slag sample to be tested inside a testing unit; heating water in a heating chamber to produce steam for delivery to the testing unit containing a slag sample; measurement of the water level within the heating chamber by a water level measurement means, wherein the water level measurement means is provided at a sheltered location within the heating chamber; measurement of the expansion of the slag sample.

29. An apparatus substantially as hereinbefore described with reference to the accompanying drawings.

30. A method for expansion testing of a slag sample, substantially as hereinbefore described .

Description:
SLAG EXPANSION TESTING MACHINE AND RELATED METHOD

This invention relates to testing machines and is especially, but not exclusively, related to expansion testing machines for use in measuring the expansion of slag, e.g. steel slag .

It is known that upon contact with steam, a slag sample may expand . Without wishing to be constrained by any particular theory, it is thought that this expansion is due to the hydration of particular components present in the slag, for instance free lime. This expansion may be measured using an expansion testing machine.

Slags, for example steel slags, have utility in many applications including as aggregate in road construction. However, use for such applications is typically subject to regulations and/or compliance with the limits set in the standard relevant to the specific application. For instance, it may be required that expansion of the slag to be consistently below a given threshold .

In Europe, slag for use as aggregate in road construction must be tested in accordance with EN1744-1 : 2009. EN 13043 is the standard relevant to aggregates for bituminous mixtures and surface treatments for roads, airfields and other trafficked areas.

In a known machine, testing of the expansion of slag is carried out by heating water in a heating unit to produce steam, passing the steam through a sample of slag contained in a pot positioned above the heating unit, and measuring the resulting upward movement of a surcharge, e.g. a weight, placed on the slag sample to determine the volume increase. The test duration can be from 24 hours to 168 hours depending on the level of MgO in the slag . During the course of the test it will be necessary to replenish the water in the heating unit. However, it may be difficult to determine when and how much water to add . This may result in significant variations in temperature in the heating unit, which in turn may affect steam production. This approach may also lead to inefficiencies in water and energy usage.

It is an object of the present invention to provide a testing machine which may be more efficient and/or safer and/or more reliable than known machines.

Accordingly, a first aspect of the invention resides in an apparatus for expansion testing of slag samples, e.g. steel slag samples, comprising : at least one heating chamber, in which water is heatable to produce steam for delivery to a testing unit containing a slag sample; and water level measurement means for measuring the level of water within the heating chamber; wherein the water level measurement means is provided at a sheltered location within the heating chamber.

Herein, by 'sheltered location' is meant a position in which the surface of the water in the heating chamber is less turbulent, in use, due to the shape of the heating chamber and/or a structure or formation within it. In an area of lower turbulence, there will be less variation in the water level at that location, and so a more accurate measure of the water level in the heating chamber may be achieved. This is advantageous as smaller changes in the water level in the heating chamber may be reliably measured. Hence, smaller amounts of water may be added to the heating chamber at a given time and, consequently, variations in the temperature of the water may be minimised .

Preferably, the sheltered location in which the water level measurement means is positioned may be provided by means of an alcove, a cavity or a recess. The heating chamber preferably comprises a base and at least one side wall extending upwardly therefrom. Preferably, the alcove, cavity or recess may be formed between a pair of side walls of the heating chamber. Alternatively, the alcove, cavity or recess may be formed in the or a side wall of the heating chamber. Preferably, the alcove, cavity or recess may extend for substantially the full height of the heating chamber.

Additionally or alternatively, the sheltered location may be provided by means of a barrier, e.g. a screen or a lattice, or a baffle located within the heating chamber.

Preferably, water in the at least one heating chamber is heated by means of a heating element positionable at least in part within the heating chamber. Alternatively or additionally, water in the heating chamber may be heated by another means, such as by an external heat source, e.g. by application of heat to an outer surface of the at least one heating chamber.

In use, water enters the heating chamber, preferably through water inlets positioned in a side wall or base of the heating chamber. Inflow of water through the water inlets may be controlled by means of a valve, preferably a solenoid valve.

Preferably, the apparatus comprises a housing in which the heating chamber is located.

The apparatus may further comprise at least one testing unit, in which a slag sample is contained, in use, comprising at least one inlet for steam. Preferably, said testing unit may comprise a pot, which may be generally cylindrical in shape. Preferably, the at least one inlet may be provided by a plurality of holes provided in a base and/or a side wall of the testing unit.

The test unit, e.g. the pot, is preferably encasable, in use, by a heatable jacket. In use, the heatable jacket may act to maintain the testing unit at a temperature of 100 ° C or more, preferably approximately 110 ° C, thereby preventing or at least minimising condensation. Preferably, a single testing unit is associated with each individual heating chamber.

Preferably, the testing unit may be securable above an individual heating chamber. Preferably, the testing unit may be securable above an individual heating chamber by interengagement between the testing unit or a portion thereof and the or a housing, in which the heating chamber is located .

Preferably, the apparatus further comprises a top plate, preferably formed of a metal sheet. Preferably, the heating chamber is fixed to the top plate, optionally by welding. Preferably, the heating chamber may be fixed underneath the top plate, e.g. such that the top plate is fixed to the top of the or a wall or walls of the heating chamber.

Preferably, the top plate may comprise at least one major aperture to provide an opening into a heating chamber located therebelow. Preferably, the major aperture may be round in shape, though other shapes may be suitable.

Preferably, the major aperture is bound by a groove suitable for receiving a sealing ring. In use, a sealing ring may be placed in the groove around the major aperture. This acts to improve the seal between the testing unit and the housing, hence preventing or at least minimising unwanted loss of steam.

The testing unit may be adapted to be capable of being secured to the housing such that it may be positioned, in use, over the major aperture in the housing and the heating chamber therebelow.

Preferably, the testing unit may comprise a flange for fixing the testing unit in place relative to the heating chamber. Preferably, the flange may comprise a chamfered portion, e.g. a chamfered edge. For instance, the flange may comprise one or more gaps positioned around the perimeter thereof. In preferred embodiments having a plurality of gaps, e.g. three gaps, the gaps may be equally spaced around the perimeter of the flange. The or each gap may be defined at least partially by a chamfered edge.

Preferably, the housing comprises a set of holding projections, e.g. three holding projections. The set of holding projections is preferably positioned, e.g. at regular intervals, such that the holding projections correspond to the position of the gaps located around the flange of the testing unit. Preferably, the holding projections are positioned, e.g. at regular intervals, around the major aperture.

Preferably, the holding projections of the housing pass through the gaps in the flange such that when the testing unit is rotated, the holding projections slide over the flange and secure the testing unit in place.

Preferably, the water level measurement means may be provided by a probe. Typically, the probe may measure the water level within the heating chamber by detecting electrical conductivity through the water between the probe and the side wall of the heating chamber. Of course, other water level measurement means may be provided without departing from the scope of the present invention. For instance, any type of contact or non-contact water level sensor may be provided, such as magnetic sensors, mechanical float sensors, vibration sensors, capacitance sensors, optical sensors, microwave sensors, magnetostrictive sensors, resistance sensors, sonic or ultrasonic sensors, e.g. pulsed wave ultrasonic sensors, or other conductivity sensors.

The probe preferably comprises a plurality of rods, e.g. three rods, each of which extends to a different depth within the heating chamber. The rods may be made from stainless steel . Where conductivity between a rod and the wall of the heating chamber is lost, it can be inferred that the water level lies below the end of that rod. The different depths to which the rods extend within the heating chamber may be regularly or irregularly spaced . In a preferred embodiment having three rods, the longest rod may extend to a depth of from 1 to 3 cm, e.g . 2 cm, greater than the middle rod, which may in turn extend to a depth of from 1 to 3 cm, e.g . 2 cm, greater than the shortest rod . The lengths of the rods and the depths to which they extend will be selected in relation to the size of the heating chamber and the position of the or a heating means, e.g . heating element, located within the heating chamber.

Preferably, the rods may be substantially straight and extend substantially vertically into the heating chamber.

Alternatively, the rods may comprise a bend or kink and enter the heating chamber through a side wall before extending downwardly within the heating chamber. Such an arrangement is known in the art; however, it may be less preferred, since it can sometimes be prone to short circuits caused by undesirable build up of lime scale on the substantially horizontal section leading to the side wall.

The testing unit may further comprise a handle for assisting rotation of the unit when securing it in place.

Preferably, the testing unit also comprises a movable element, having a single degree of freedom such that, in use, the element may move as a consequence of expansion of a slag sample in the testing unit.

In preferred embodiments, the movable element may be a lid component, which is preferably movable in a substantially vertical direction. Preferably, a surcharge, e.g. a weight, may be positioned above said lid component, thereby providing a resistance to upward movement of the lid caused by expansion of the slag sample.

The apparatus may further comprise at least one means for measuring the expansion of the slag sample, e.g. by detecting movement of the or a movable element. Preferably, the expansion measurement means may comprise a potentiometer. The potentiometer may comprise a transducer that is specially adapted to cope with heat and moisture.

The apparatus may further comprise a means for supporting the expansion measurement means, preferably a frame. The frame preferably comprises at least one swing arm, more preferably two swing arms. Typically, the apparatus may comprise one swing arm per testing unit. The position of the at least one swing arm may optionally be adjusted, preferably by a series of hand wheels. The frame secures the expansion measurement means in position, preferably by a clamping mechanism for receiving and holding, in use, a portion of the expansion measurement means. In embodiments comprising a lid component movable in the vertical direction, the expansion measurement means is preferably held in a vertical position.

Preferred embodiments of the apparatus will carry out testing in compliance with EN1744-1 : 2009.

A second aspect of the invention resides in a testing unit for use in expansion testing of slag samples comprising a container for receiving a slag sample, in use, and a base having a flange comprising a chamfered portion.

Preferably, the flange may be discontinuous, e.g. to provide at least one gap.

Preferably, the or each gap is an open-ended gap.

Preferably, the or each gap is defined by a pair of opposed flange portions.

Preferably, one of the opposed flange portions comprises the chamfered portion. In embodiments where there are plural gaps, each gap may be spaced equally from another around the perimeter of the flange.

A third aspect of the invention provides an apparatus for expansion testing of slag samples comprising a testing unit according to the second aspect of the invention.

A fourth aspect of the invention resides in an apparatus for expansion testing of slag comprising a frame for supporting at least one expansion measurement means, the frame comprising at least one swing arm, wherein the at least one swing arm comprises a clamping mechanism for receiving and holding, in use, a portion of the at least one expansion measurement means, and a means of adjusting the position of the swing arm relative to the frame such that the orientation of the at least one expansion measurement means may be manipulated such that, in use, the expansion measurement means is positioned and orientated to measure expansion of a slag sample within a testing unit adapted to permit expansion in an allowed direction.

Preferably, the allowed direction is substantially vertical, in which case the at least one expansion measurement means may be held, in use, in a substantially vertical position.

Preferably the frame comprises two swing arms on a single frame.

Preferably the position of the at least one swing arm may be adjusted by a series of hand wheels.

A further aspect of the invention provides a method for expansion testing of a slag sample comprising : placing a slag sample to be tested inside a testing unit; heating water in a heating chamber to produce steam for delivery to the testing unit containing the slag sample; and controlling the water level within the heating chamber by measuring the water level using a water level measurement means and adding water when the water level falls by a pre-determined amount, wherein the water level measurement means is provided at a sheltered location within the heating chamber.

In order that the invention may be more fully understood, a preferred embodiment of an apparatus in accordance with the invention will now be described by way of example and with reference to the accompanying drawings, in which :

Figure 1 is a perspective view of the apparatus according to the invention,

Figure 2 is a side view of the apparatus shown in Figure 1,

Figure 3 is a perspective view of a heating unit of the apparatus shown in Figure 1,

Figure 4 is a perspective view of the heating unit shown in Figure 3 where the heating unit has been rotated anti-clockwise through 90°,

Figure 5 is a plan view of the heating unit shown in Figures 3 and 4,

Figure 6 is a perspective view of a testing unit of the apparatus shown in Figure 1,

Figure 7 is a cross-sectional view of the testing unit shown in Figure 6,

Figure 8 is a perspective view of the lid component of the testing unit shown in Figure 6,

Figure 9 is a plan view of a perforated disc of the lid component,

Figure 10 is a side view of a frame of the apparatus shown in Figure 1,

Figure 11 is a plan view of the frame shown in Figure 10, Figure 12 shows one embodiment of a water level measurement means,

Figure 13 shows a second embodiment of a water level measurement means, and

Figure 14 shows a perspective view of a portion of an alternative apparatus arrangement.

Referring first to Figure 1, there is shown an apparatus indicated generally at 100. The apparatus 100 comprises a housing having an upper housing portion 114 and a lower housing portion 115. The upper housing portion

114 overhangs the lower housing portion 115.

The lower housing portion 115 comprises a recess 102, which may be accessed by means of a panel 108 attached to the lower housing portion

115 by a hinge (not shown).

Located in recess 102 is a mains water inlet manifold 103. The mains water inlet manifold 103 is regulated by a solenoid valve 105.

Also located in recess 102 are a first tank drain pipe 112a and a second tank drain pipe 112b. First tank drain pipe 112a is controlled by means of a first ball valve 104a, similarly, second tank drain pipe 112b is controlled by means of a second ball valve 104b.

The upper housing portion 114 comprises an access plate 116, which is screwed on to the upper housing portion 114 and allows access to the interior of the upper housing portion 114 for the purpose of maintenance.

The upper housing portion 114 further comprises a top plate 101, in which there is a first major aperture 109a and a second major aperture 109b. Each of the major apertures 109a, 109b provides a round opening into the space therebelow. Major apertures 109a, 109b are substantially identical. Each of the major apertures 109a and 109b measures 19 cm in diameter. First major aperture 109a is bounded by a first groove 118a suitable for receiving a sealing ring . Similarly, second major aperture 109b is bounded by a second groove 118b suitable for receiving a sealing ring.

Top plate 101 further comprises a first set of three holding projections 110a, regularly spaced around the first major aperture 109a, and a second set of three holding projections 110b, regularly spaced around the second major aperture 109b.

It is to be appreciated that there may be fewer than or more than three holding projections 110a. It may be most preferred that the holding projections 110a are regularly spaced around first major aperture 109a. Similarly, there may be fewer than or more than three holding projections 110b, with it being most preferred that the holding projections 110b are regularly spaced around major second aperture 109b.

The holding projections 110a, 110b are formed such that there is a space between a portion of a given projection and the top plate 101 suitable to receive a flange.

The top plate 101 further comprises a first probe cover 111a and a second probe cover 111b. Top plate 101 also comprises a first pressure relief adaptor 113a and a second pressure relief adaptor 113b.

Extending upwards from the top plate 101 is a frame generally indicated at 200. Frame 200 comprises a top bar 201 supported by two posts 202, such that the posts 202 are fixed to the top plate 101.

The posts 202 of the frame 200 are hollow such that they may house electrical wiring and the like out of view, thereby improving safety and aesthetics. The posts 202 also comprise power mounting plates 213 which accommodate the necessary electrical connection points to operate the apparatus. A first swing arm 203a is pivotally fastened by means of a first cleat 214a to the top bar 201, such that the first swing arm 203a may be moved to extend over the first major aperture 109a. A second swing arm 203b is pivotally fastened by means of a second cleat 214b to top bar 201, such that the second swing arm 203b may be moved to extend over the second major aperture 109b.

Figure 2 shows a side elevation of the apparatus 100. The panel 108 is in a partially open position providing a view into the recess 102. Located in recess 102 is distribution manifold 106, having an inlet, a first outlet pipe 117a and a second outlet pipe 117b. The first outlet pipe 117a is regulated by means of a first solenoid valve 107a, and the second outlet pipe 117b is regulated by means of a second solenoid valve 107b. A pipe (not shown) provides fluid communication, in use, between the mains water inlet manifold 103 and the inlet of the distribution manifold 106.

In Figure 14 there is shown an alternative arrangement in which the mains water inlet manifold 103' and distribution manifold 106' are mounted to panel 108'. Such an arrangement provides for a simplified pipe network. In this embodiment the mains water inlet manifold 103' is regulated by a solenoid valve 105'. A pipe 119' provides fluid communication between the inlet manifold 103' and the distribution manifold 106'. The distribution manifold 106' comprises a first outlet pipe 117a' and a second outlet pipe 117b'. The first outlet pipe 117a' is regulated by means of a first solenoid valve 107a' and the second outlet pipe 117b' is regulated by a second solenoid valve 107b'. The mains water inlet manifold 103' further comprises an inlet port 120', e.g. a nozzle, for attachment to a water source. The pipe network ensures that water is transferred in a controlled manner from the source through the panel 108' towards the heating units described below.

The apparatus 100 further comprises a first heating unit 310a and a second heating unit 310b. Figure 3 shows the first heating unit 310a, which will now be described in more detail. It should be appreciated that the first heating unit 310a and the second heating unit 310b are substantially identical.

The first heating unit 310a comprises heating chamber 300a. The heating chamber 300a is defined by a base 311a and, extending upwardly from the base 311a, a first side wall 312a, a second side wall 313a, a third side wall 314a, and a fourth side wall 315a. The first side wall 312a and the second side wall 313a are joined at a right angle, similarly, the second side wall 313a and the third side wall 314a are joined at a right angle, and the third side wall 314a and the fourth side wall 315a are joined at a right angle. An alcove 305a joins the first side wall 312a and the fourth side wall 315a. The alcove 305a extends the full height of the first side wall 312a and the fourth side wall 315a.

The top plate 101 is welded onto the top of the side walls, such that the first major aperture 109a provides an opening into heating chamber 300a therebelow.

Figure 3 shows a portion of top plate 101. The top plate 101 is screwed onto the upper housing portion 114 through apertures not shown in the drawing .

A water inlet 301a is provided in the second side wall 313a. A pipe (not shown) provides fluid communication between the water inlet 301a and the first outlet pipe 117a exiting the distribution manifold 106.

The second side wall 313a also comprises attachments 302a, which allow for a heating element to be introduced into the heating chamber 300a.

As shown in Figure 4, extending out from the base 311a of the heating chamber 300a beyond the fourth side wall 315a is formed a drain pipe assembly 303a. A pipe (not shown) provides fluid communication between the drain pipe assembly 303a and the first tank drain pipe 112a. A first minor aperture 304a is formed in the top plate 101 such that it is situated directly above alcove 305a. The first minor aperture 304a is formed to allow a probe (examples of which are shown in Figures 12 and 13) to pass therethrough and extend into the alcove 305a of the heating chamber 300a therebelow.

The probe 600 of Figure 12 comprises three stainless steel rods 601, 602, 603, which extend to increasing depths within the alcove, wherein the shortest rod 603 extends to a depth 20 mm less than the middle rod 602, which in turn extends to a depth of 20 mm less than the longest rod 601. The rods 601, 602, 603 enter the heating chamber through the top plate 101 and are substantially straight.

Each rod 601, 602, 603 serves as a sensor to detect water in the heating chamber 300a. Due to the differences in length of the rods 601, 602, 603, variations in the water level within the heating chamber 300a may be measured . The probe 600 positioned to extend into first heating chamber 300a is concealed from view by first probe cover 111a.

The probe 600 determines the water level in the heating chamber 300a by measuring the conductivity between each rod 601, 602, 603 and the side wall of the heating chamber 300a. The rod 602 of medium length is the operating rod, which extends to a depth that corresponds substantially with the optimum water level.

At the optimum water level, conduction is measured by both the longest rod 601 and the operating rod 602. As the water level drops below the optimum water level and hence below the length of the operating rod 602, conduction is no longer detected by the operating rod 602. This triggers the addition of water to the heating chamber 300a. If the water level drops even lower such that conduction is no longer detected by the longest rod 601, the heating element is switched off until the water level reaches a higher level, i.e. such that it is detected by the longest rod 601. This is to prevent possible burn out of the heating element. Conversely, if the water level in the heating chamber 300a is such that conduction is detected in all three rods 601, 602, 603, no more water is added to the heating chamber 300a until the water level drops below the level detected by the shortest rod 603.

The probe is said to have detected a failure mode either when water is not detected by the longest rod 601, or when water is detected by the shortest rod 603. The failure mode is recorded by a control means, e.g. a Programmable Logic Controller (PLC) associated with the apparatus.

In an alternative, but less preferred, embodiment shown in Figure 13 the probe 600' comprises three rods 601', 602', 603' each comprising a 90° bend . The rods 601', 602', 603' enter the heating chamber through a side wall of the heating chamber and extend downwards into the heating chamber. In this embodiment the three rods 601', 602', 603' have vertical lengths of 20 mm, 40 mm and 60 mm. An embodiment such as this may be less preferred, since this arrangement can sometimes be more susceptible to short circuits than embodiments comprising straight rods, due to lime scale build up on the substantially horizontal section of the rods.

Referring back to Figure 4, first heating unit 310a further comprises a second minor aperture 316a, through which the first pressure relief adaptor 113a extends into the heating chamber 300a. The o-ring 306a forms a seal around the minor aperture 316a.

Referring to Figure 5, it is can be seen that the alcove 305a is defined by a first alcove side wall 317a, a second alcove side wall 318a, and a third alcove side wall 319a. The second alcove side wall 318a is joined to the third alcove side wall 319a along its height, similarly the third alcove side wall 319a is similarly joined to the first alcove side wall 317a.

The first alcove side wall 317a is joined to the first side wall 312a of the heating chamber 300a along its height and the second alcove side wall 318a is joined to the fourth side wall 315a. As can be seen in Figure 5, the three alcove side walls 317a, 318a, 319a define a shape which resembles three sides of a regular trapezium without a base. In plan-view, as shown in Figure 5, the heating chamber 300a is symmetrical about a line bisecting the third alcove side wall 319a and the opposite corner of the heating chamber 300a where second side wall 313a meets third side wall 314a.

It is also shown in Figure 5 that the first major aperture 109a is offset from the centre of the heating chamber 300a of first heating unit 310a towards the second side wall 313a.

It is to be appreciated that an alcove, a recess or a cavity defined by a different shape and positioned in a different location in the heating chamber may also be considered, provided that it provides a sheltered location for the probe or other water level measurement means.

The apparatus 100 also comprises a first testing unit 500a and a second testing unit 500b. The first testing unit 500a is positioned over the first major aperture 109a. Similarly, the second testing unit 500b is positioned over the second major aperture 109b. Figure 6 shows first testing unit 500a which will be described below. The first testing unit 500a and the second testing unit 500b are substantially identical.

The first testing unit 500a comprises a pot 501a. The pot 501a is defined by a hollow cylinder fixed to a base 502a. The pot 501a is encasable, in use, by a heatable jacket 516 (only shown in Figure 7). In use, the heatable jacket 516 acts to maintain the pot 501a at a temperature of approximately 110°C, thereby preventing or at least minimising condensation.

The base 502a is provided with an array of holes 503a such that steam may pass, in use, through the base 502a via the holes 503a and into the pot 501a. The base 502a of first testing unit 500a also provides a flange 513a having three gaps 510a regularly spaced around its circumference. A chamfered edge 511a is provided adjacent each of the three gaps 510a.

The gaps 510a are spaced to correspond with the first set of three holding projections 110a on the top plate 101.

It is to be appreciated that in the case where there are fewer than or more than three holding projections 110a, there will also be a corresponding number of appropriately spaced-apart gaps 510a.

The first testing unit 500a further comprises a handle 512a attached to the flange 513a by three upright supports 514a. The handle 512a extends around approximately three quarters of the circumference of the testing unit 500a.

When securing the first testing unit 500a in place, a rubber sealing element (not shown) is placed in the first groove 118a. Then, the first testing unit 500a is placed over the first major aperture 109a in the top plate 101 such that the first set of three holding projections 110a extend through gaps 510a in the base 502a of the testing unit 500a.

The first testing unit 500a is then rotated such that the first set of holding projections 110a slide over the flange 513a of the first testing unit 500a, aided by the chamfered edges 511a adjacent the gaps 510a. Advantageously, rotation of the first testing unit 500a may be carried out manually, aided by the handle 512a.

The provision of chamfered edges 511a facilitates rotation of the testing unit when securing it in place and also improves the seal around the major aperture.

Referring to Figure 7, first testing unit 500a further comprises a lid component indicated generally at 507a. The lid component 507a rests on the contents of the pot 501a, in use, and is free to move up and/or down in a substantially vertical direction. Typically, in use, a filter mat (not shown) will be placed between the contents of the pot and the lid .

Referring to Figure 8, the lid component 507a comprises a top 504a separated from a perforated disc 505a by means of four regularly spaced- apart spacers 506a. In the centre of the top 504a is positioned a weight locator 508a, about which a weight 509a is positioned .

Referring to Figure 9, the perforated disc 505a comprises perforations 515a extending in a series of concentric circles about the centre of the perforated disc 505a.

In use, a first potentiometer, indicated generally in Figure 2 as 700, is positioned such that it rests on the upper surface of the lid component 507a of the first testing unit 500a and can therefore detect expansion of a slag sample contained therein. The first potentiometer 700 is supported by means of the frame 200.

The frame 200 comprises a top bar 201 supported by two posts 202, as shown in Figure 10.

A first swing arm 203a and a second swing arm 203b extend from opposite sides of the top bar 201. The first swing arm 203a and the second swing arm 203b are substantially identical .

The components of the frame 200 and/or swing arms 203a, 203b may be formed from any suitable metal or alloy, e.g. stainless steel. The components of the frame 200 and/or swing arms 203a, 203b may be solid or comprise hollow channel.

Figure 10 shows a side elevation of the frame 200 such that the first swing arm 203a can be seen.

Figure 11 shows that the second swing arm 203b is similarly fastened to the top bar 201 by means of a second cleat 214b. Again referring to Figure 11, a plan view of both the first swing arm 203a and the second swing arm 203b is shown . Since the first swing arm 203a and the second swing arm 203b are substantially identical, only the first swing arm 203a will be described here in detail.

The first swing arm 203a is pivotally fastened to a side of the top bar 201 by means of a first cleat 214a. A first hand wheel 204a is provided to allow the swing arm 203a to be secured in a desired orientation relative to the top bar 201.

The first swing arm 203a comprises a swing bar 205a pivotally fastened to one end of a hinge bar 206a and securable in place by means of a second hand wheel 207a. The other end of the hinge bar 206a is pivotally fastened to a mounting block 208a, and securable in position by means of a third hand wheel 209a.

Mounting block 208a is further attached to clamp 210a, such that the mounting block 208a and clamp 210a define a hollow 211a for receiving a portion of the first potentiometer 700. A fourth hand wheel 212a acts to move the mounting block 208a and clamp 210a together, such that the first potentiometer may be held in place.

Manipulation of the hand wheels 204a, 207a, 209a, and 212a allow the first swing arm 203a to be positioned and secured over the first major aperture 109a, and hence the first potentiometer 700 to be held vertically over the first testing unit 500a. The frame and swing arms may provide a more reliable, consistent and/or accurate means for holding an expansion measurement means such as a potentiometer in a desired alignment, e.g. in a vertical position. Consequently, the results of expansion tests carried out using the machine may be more reliable.

The operation of the apparatus 100 will now be described. A first slag sample is placed in the pot 501a of the first testing unit 500a. The lid component 507a is then placed on top of the slag sample. Weight 509a is positioned about the weight locator 508a such that the lid component 507a provides resistance to the expansion of the slag . A second slag sample is similarly placed in second testing unit 500b. In order to comply with EN1744-1 : 2009, the slag samples may need to be compacted so as to reduce the void content to 25 ± 3% by volume .

First testing unit 500a is then placed over the first major aperture 109a in the top plate 101 such that the first set of three holding projections 110a extend through gaps 510a in the base 502a of the first testing unit 500a. The first testing unit 500a is then rotated such that the first set of holding projections 110a slide over the flange 513a of the first testing unit 500a, aided by the chamfered edges 511a adjacent the gaps 510a. Rotation of the first testing unit 500a is carried out manually, aided by the handle 512a.

A sealing ring is situated in groove 118a and acts to create a tight seal when the first testing unit 500a is secured to the top plate 101. The chamfered edges 511a ease the rotation of the first testing unit and, together with the action of the holding projections 110a receiving the flange 513a, enable the first testing unit 500a to be tightly sealed and strongly secured to the top plate 101. Second testing unit 500b is similarly positioned and secured over the second major aperture 109b. This securing and sealing arrangement may improve operational reliability and/or safety.

First major aperture 109a provides an opening into the heating chamber 300a of first heating unit 310a therebelow. Similarly, second major aperture 109b provides an opening into the heating chamber 300b of second heating unit 310b therebelow.

The first potentiometer 700 is positioned in the hollow 211a between the mounting block 208a and clamp 210a, and secured in place by tightening hand wheel 212a. Through use of hand wheels 204a, 207a and 209a, the first swing arm 203a may be manipulated such that the first potentiometer 700 is positioned above the lid component 507a of the first testing unit 500a, wherein the first potentiometer 700 is touching the lid component 507a of the first testing unit 500a.

Similarly, the second swing arm 203b of the frame 200 is manipulated such that the second potentiometer rests above the second testing unit 500b, such that the second potentiometer is touching the lid component 507b.

The frame provides the advantage of ensuring a reliable vertical orientation of both the first and second potentiometers, therefore allowing a more accurate measure of the expansion of the slag samples.

The flow of water into the distribution manifold 106 from the mains water inlet manifold 103 is controlled by solenoid valve 105 positioned on the mains water inlet manifold 103.

The flow of water from the first outlet pipe 117a of the distribution manifold 106 is controlled by solenoid valve 107a, positioned at the first outlet pipe 117a exiting the distribution manifold 106. Similarly, the flow of water from the second outlet pipe 117b of the distribution manifold 106 is controlled by solenoid valve 107b, positioned at the second outlet pipe 117b exiting the distribution manifold 106.

Water enters the heating chamber 300a via water inlet 301a, supplied by means of mains water inlet manifold 103 and the distribution manifold 106, and is heated by an electric heating element (not shown) to form steam. The steam rises from the heating chamber 300a and passes into the pot 501a of first testing unit 500a via holes 503a in the base 502a. Similarly, steam is produced in second heating unit 310b and is delivered to the second testing unit 500b.

Steam is produced in the first and second heating chambers 300a, 300b and rises, passing into the first and second testing units 500a, 500b via holes in the bases of the first and second testing units 500a, 500b. In order to comply with EN1744-1 : 2009, the water usage may be 1.1 ± 0.6 l/hr.

Generally, producing steam in the manner described may be advantageous over other methods e.g . using a steam generator, since it can provide greater control over the volume of steam produced.

Upon contact with steam, the first slag sample within pot 501a expands causing upward movement of the lid component 507a of the first testing unit 500a. This movement, and hence the expansion of the slag, is measured using the first potentiometer 700. Similarly, expansion in the second sample is measured by the second potentiometer.

The water level inside the first heating chamber 300a is measured using a first probe 600, which extends into the alcove 305a of the heating chamber 300a through aperture 304a in the top plate 101. The probe 600 is located in alcove 305a such that it is positioned at a sheltered location away from the heating element in an area of the heating chamber 300a where the water is less turbulent, thereby enabling an accurate measure of the water level to be obtained. A second probe 600 is similarly positioned in the second heating chamber 300b.

The first and second probes 600 each comprise three rods 601, 602, 603 of different lengths for sensing the water level. As described above, since the rods 601, 602, 603 are positioned, in use, at a sheltered location within the heating chamber, variations in the water level are more reliably and accurately detected. Accordingly, relatively small additions of water will generally be required in order to maintain the water level at or close to the desired level and to maintain a steady simmer. This close control is advantageous, as it is more efficient in terms of water usage and in terms of energy usage by the heating element (the temperature of the water, in use, will be less volatile). If the probe 600 were to be positioned in an area of more turbulent water, i.e. not in a sheltered location, then the water level may vary by an amount greater than the difference in the lengths of the rods 601, 602, 603, and therefore may lead to false readings. To reduce the number of false readings, a greater difference in the lengths of the rods 601, 602, 603 of the probe 600 would be required, consequently only larger variations in the water level could be measured, resulting in reduced control in the amount of water required to top up the heating chamber.

Maintaining the water in the heating chambers 300a, 300b at a steady simmer rather than a rapid boil also increases the accuracy of the measurements made by the rods 601, 602, 603 due to reduced turbulence in the water and so results in a reduction in the number of false readings.

The water level in heating unit 300a is controlled using a Programmable Logic Controller (PLC) which, in response to readings from the probe 600, regulates the volume of water introduced into the first heating chamber 300a through the water inlet 301a by controlling solenoid valve 105a, which regulates the water supplied by the mains water inlet manifold 103, and solenoid valve 107a, which regulates the water supplied by the first outlet pipe 117a of the distribution manifold 106. The water level in the heating unit 300b of the second heating unit 310b is similarly controlled .

The probe 600 detects a failure mode either when water is not detected by the longest rod 601, or when water is detected by the shortest rod 603. The occurrence of this failure mode is recorded by the PLC.

The temperature of the water in the heating chambers 300a, 300b may be measured by temperature sensing means (not shown). The heating element may be controlled to regulate the temperature in the heating chambers. The power supplied to the heating element, in use, will preferably be controlled so as to maintain a steady simmer of the water in the heating chamber. Maintaining a steady simmer, i.e. a relatively consistent level of turbulence of the water surface, will help to ensure that the number of false readings is reduced. The PLC is linked to a Human Machine Interface (HMI). The PLC and/or HMI can be arranged to provide data to a computer at a remote location, for example for analysis of the performance of the machine.

Control of the water level and/or water temperature in this manner permits the addition of smaller amounts of water to the heating chambers as and when required. This enables a more constant temperature profile to be maintained, reducing the amount of energy required to keep the water in the heating chamber boiling and ensuring a steadier production of steam. Close control of the water level and/or water temperature also results in lower water consumption overall, reducing the build up of lime scale in the machine, meaning that the machine may require maintenance less often and/or will operate optimally for longer periods.

Maintaining the water at a steady simmer rather than a rapid boil also may have safety benefits for operators of the apparatus.

Perforated disc 505a of the lid component 507a allows steam to escape, in use, after it has passed through a slag sample, thereby minimising the build-up of pressure within the pot 501a. First pressure relief adaptor 113a and second pressure relief adaptor 113b are operable to ensure that the pressure inside the first heating unit 310a and the second heating unit 310b respectively does not become too great.

When necessary, for example at the end of a test, water may be removed from the heating chamber 300a of first heating unit 310a via drain pipe assembly 303a. There is fluid communication between drain pipe assembly 303a and tank drain pipe 112a through a pipe not shown in the drawings. Water is removed from the heating chamber 300a by opening ball valve 104a. Drainage is similarly achieved for heating chamber 300b of second heating unit 310b.

A typical expansion test of slag samples using the apparatus 100 will now be described . The expansion of two slag samples was tested for a period of up to seven days, during which time steam generated in the heating chambers passed through the slag samples and the consequent expansion of the samples was measured.

When necessary, water was added to the heating chamber in 25ml amounts - such relatively small additions could be made due to the accurate measurement of the water level by the sheltered sensors and/or the close control of power to the heating elements. Addition of such small amounts may ensure the water is kept continually boiling, i.e. at a constant, steady simmer, and that there is consequently a steady production of steam.

During the test, it was found that each heating unit consumed 0.7 litres per hour of water. This relatively low water consumption is beneficial, first because less water is required to carry out the test, and secondly because lower water consumption may lead to reduced lime scale build up in the machine.

Water in each heating chamber may be heated by a heating element. Control of the temperature and the incremental addition of water to the heating chamber are such that the heating element need only be on for approximately 25% of the test, resulting in lower energy consumption.

In another preferred embodiment of a slag expansion apparatus according to the invention, ten slag samples may be tested simultaneously. In this embodiment, five of the apparatus 100 as described above are essentially placed adjacent one another such that the slag samples form a five by two arrangement.

In such a ten sample arrangement, there may be one distribution manifold comprising ten outlet pipes, each providing water to one of the ten heating chambers. Each outlet pipe will be controlled by means of a solenoid valve. Conveniently, there may be only one mains water inlet manifold in the ten sample arrangement.

Each of the ten heating chambers comprises a drain pipe assembly and so there are ten corresponding tank drain pipes allowing drainage of water from each of the ten tanks.

In an alternative embodiment, the alcove may be defined by a different shape and be located at a different position in the heating chamber. For instance, the alcove may not extend the entire height of the heating chamber. Also, the sheltered location may be provided by a recess or cavity in the base or a side wall. The recess or cavity may be formed of a box-like shape, or alternatively may be hemispherical in shape. In another embodiment, the alcove could be defined by a semi-cylindrical shape formed between two side walls of the heating chamber and extending up part or all of the height of the heating chamber.

Alternatively, the probe may be positioned inside the body of the heating chamber itself, and sheltered from the most turbulent water in the heating chamber by means of a shielding device such as a barrier, a screen, a mesh or a net or a baffle within the heating chamber.

The invention is also not to be limited by the shape defining the heating chamber. The heating chamber may take an alternative form while falling within the scope of the invention. For instance, the heating chamber may be defined by one wall in a hemispherical shape. Or, in an alternative embodiment the heating chamber may comprise one side wall and a base forming a cylindrical shape.

Of course, it is also possible according to the invention to construct an expansion testing machine which measures the expansion of just one sample of slag. However, typically it may be preferred for the apparatus to comprise one or more pairs of testing units, since relevant standards, e.g . EN1744-1 : 2009, may require that tests are carried out in duplicate. It has been found that the apparatus according to the invention tests to the required standards and regulations for the use of slag as aggregate in road surfaces. It is to be appreciated that the machine may be suitable for the testing of slag samples to ensure the standards required for alternative applications are met.

It is also to be appreciated that the apparatus according to the above described invention may be suitable for testing the expansion of other materials, and/or that liquids other than water may be used.