EP2951519B1

EP2951519B1 - A furnace for preparing fused (homogenised) samples for sample analysis

Info

Publication number: EP2951519B1
Application number: EP13873188.0A
Authority: EP
Inventors: Boyne Friederich HOHENSTEIN
Original assignee: Imp Group Pty Ltd
Current assignee: Imp Group Pty Ltd
Priority date: 2013-01-31
Filing date: 2013-01-31
Publication date: 2018-08-29
Anticipated expiration: 2033-01-31
Also published as: EP2951519A4; WO2014117202A1; EP2951519A1

Description

Field of the Invention

The present invention broadly relates to a furnace for preparing fused (homogenised) samples for sample analysis.

Background of the Invention

A variety of samples such as mineral samples, cement samples and other materials need to be homogenized (or fused) before they can be analysed by analytical techniques such as X-Ray fluorescence (XRF) spectrometric analysis, inductively-coupled plasma mass spectrometry (ICP MS) and many other analytical techniques. Sample preparation typically involves mixing the sample with a flux and placing the mixture in a furnace that is heated to form a homogeneous melt.
In the case of XRF analysis the homogenized melt is allowed to cool in a crucible to form a glass bead which is then analyzed or the homogenized melt is cast into a mould which is typically preheated and allowed to cool into a glass bead prior to the analysis.
In the case of wet chemistry analyses, the homogenized mix can be allowed to cool before it is digested in an acid or acid mix. Alternatively, the molten homogenized sample can be cast into a container, containing the appropriate acid. Once digested, the sample can be further diluted before it is analysed using suitable wet chemistry techniques.
Available fusion systems that are designed for the above-mentioned purposes allow for batch operation. A batch of the crucibles loaded with the mixture of sample and flux material is places into a furnace. The furnace is then closed and samples are heated. After heat treatment the furnace is opened and the batch of the samples is removed. Such batch operation has practical disadvantages as it is cumbersome and time consuming to load and unload the furnace. EP-A 2 458 388 , EP-A 1 455 175 , DE-A 10 2007 006 553 relate to similar furnaces for preparing of laboratory samples featuring a carousel accommodating the crucibles. PCT publication number WO2003098140 and South African patent number 2005/05485 disclose a furnace that has a carousel for movement of the batch of samples about an axis. The present invention provides further improvement.

Summary of the Invention

The present invention as defined in present claim 1 provides in a first aspect a furnace for preparing fused (homogenised) samples for sample analysis, the furnace comprising:

a housing;
a heater arranged for heating an interior portion of the housing to a temperature sufficient for causing melting of each sample;
a carousel positioned in the housing, the carousel having a plurality of receiving stations for receiving crucibles containing respective samples, the carousel being arranged for rotating the crucibles about an axis when the crucibles are positioned in respective receiving stations; and
a mechanism for moving the crucibles relative to the respective receiving stations and relative to the housing to load and unload the carousel.

The furnace may also comprise a device for measuring temperature.
The furnace typically comprises a control system that is arranged to control operation of the heater, the carousel and the mechanism for moving the crucibles. The control system typically is configured to effect removal of a crucible with the respective sample after the sample has been treated in a manner such that the sample forms a homogeneous glass when cooled subsequent to the heat treatment. The control system typically comprises a microprocessor and may be arranged to control operation of the furnace such that the first arm in use positions a sequence of crucibles into a sequence of respective receiving stations and the heater subsequently heats the samples in the crucibles during rotation of the crucibles in the carousel. Further, the control system typically is arranged to control the furnace such that the second arm removes the crucibles with respective samples sequentially from the receiving stations after completion of a predetermined heat treatment. The control system typically is arranged such that loading, rotation by the carousel, heat treatment and unloading is performed in an automated manner. Further, the control system typically is arranged such that parameters are selectable by a user. For example, the parameters may include a rotation or an oscillation rate of the carousel, a temperature of the furnace or a duration of the heat treatment.
The control system in accordance with one example comprises a timer for timing a period of time during which the samples are exposed to the heat treatment. The control system with the timer may be arranged to interrupt the heat treatment after a predetermined time or effect an alarm signal. The control system may comprise a memory device for storing control parameters.
The furnace may be arranged to impart a rocking, oscillating or vibrating motion to the samples in the crucibles when the crucibles are positioned in the receiving stations and exposed to heat treatment and which may be controlled by the control system.
Each receiving station of the carousel typically comprises an aperture that is arranged to receive a respective crucible. The furnace may comprise an arrangement for lifting and lowering the crucibles relative to the first and second arms to unload or load the crucibles form or onto the first and second arms, respectively. In this case, the control system typically is arranged such that the first arm delivers a crucible to a position over a respective receiving station and the arrangement for lowering and lifting lifts the carousel such that the crucible is positioned in the aperture of the respective receiving station.
The control system typically is arranged such that, after completion of heat treatment, the arrangement for lowering and lifting the crucible lowers the carousel to position the crucible on the second arm and the second arm then moves the crucible to a position outside the housing of the furnace.
Further, the furnace typically comprises a conveying system that is arranged for conveying a sequence of crucibles to the first arm and a sequence of crucibles away from the second arm of the mechanism for movement of the crucibles.
In one embodiment the carousel is one of a plurality of carousels. For example a first carousel may be positioned over a second carousel and arranged for rotation about the same axis.
The access door of the access port typically is arranged for remote controlled operation and the control system typically is arranged to control the operation of the access door in an automated manner to allow operation of the mechanism for moving the crucibles (which typically comprises the above-described first and/or second arm). The control system typically is arranged to control the operation of the access door in a manner such that loss of thermal energy through the access port is reduced or minimised.
The present invention as defined in present claim 10 provides in a second aspect a method of preparing fused (homogenised) samples, the method comprising the steps of:

providing a plurality of crucibles with samples to a mechanism for moving the crucibles;
moving the crucibles in sequence to respective receiving stations of a carousel of a furnace using the mechanism for moving the crucibles;
exposing the samples to heat treatment to melt the samples in the crucibles;
rotating the crucibles in respective receiving stations about an axis of the carousel and subsequently
removing the crucibles with the respective samples in sequence using the mechanism for moving the crucibles and positioning the crucibles on a conveyor for moving the crucibles away from the furnace.

The method may also comprise imparting an oscillating motion to the samples in the crucibles during fusion when the crucibles are positioned in the receiving stations.
The method typically comprises heating the samples to a temperature above the melting point of the sample flux mixture.
The invention will be more fully understood from the following description of specific embodiments of the invention. The description is provided with reference to the accompanying drawings.

Brief Description of the Drawings

Figures 1 to 4 show schematic cross-sectional views of a furnace for preparing fused (homogenised) samples in accordance with an embodiment of the present invention;
Figure 5 shows a schematic perspective view of the furnace;
Figures 6 and 7 show schematic cross-sectional views of the furnace; and
Figure 8 is s flow chart illustrating a method preparing fused (homogenised)samples in accordance with an embodiment of the present invention.

Detailed Description of Specific Embodiments

Embodiments of the present invention relate to a furnace for preparation of fused (homogenized) samples suitable for analytical techniques, such as X-ray fluorescent spectrometry or mechanical analysis techniques such as inductively-coupled plasma mass spectrometry.
Referring now to Figures 1 to 7, a furnace 100 in accordance with an embodiment of the present invention is now described. The furnace 100 comprises a housing 102 in which a carousel 104 is positioned. The carousel 104 is arranged for rotation about an axis and Figures 6 and 7 show a drive 105 of the carousel 104. The carousel 104 has a plurality of receiving stations 106 that each have an aperture and the apertures are positioned in a ring-like manner along the periphery of the carousel 104. Each aperture of a receiving station 106 is sized to receive and hold a crucible 108. The crucible 108 has a radial lip that extends in a ring-like manner at an upper portion of the crucible 108 and which rests on the carousel 104 when the crucible 108 is positioned in a respective receiving station 106.
The furnace 100 is arranged for heating samples to a temperature suitable for melting the samples to generate fused (homogenised) samples that form a homogeneous glass bead when cooled and are suitable for the above-mentioned analysis techniques. In one embodiment the furnace is arranged for heating the samples to a temperature sufficient to melt the sample and flux mixture. The samples for fusion may for example include mined materials (in powder form) or any other type of mineral that is suitably prepared. Sample preparation includes mixing with a flux material and loading a resultant mixture into the crucibles 108.
The furnace 100 also comprises a mechanism 110 for moving crucibles 108 between respective receiving stations 106 and a location that is exterior to the housing 102. The mechanism 110 comprises a first arm 112 and a second arm 114. The first arm 112 is arranged for moving the crucibles 108 from the exterior position to a respective receiving station 106 of the carousel 104. The second arm 114 is arranged for moving the crucibles 108 out of respective receiving stations 106 and to the exterior location. Both arms 112 and 114 have suitable support surfaces for supporting the crucibles 108 and are arranged for moving by suitable electrical or hydraulic means in horizontal directions.
Figure 1 shows how an end of the second arm 114 is in contact with a crucible 108. Figure 2 shows the second arm 114 after it removed the crucible 108 and is in a contracted condition. The representation of Figure 3 is similar to that of Figure 2, but the mechanism 110 moved in a direction that is transversal to the rotation direction of the carousel such that the first arm is now positioned opposite the receiving station 106 from which previously a crucible 108 was removed by the second arm 114.
Figures 4 to 6 show the first arm 112 in an extended condition in which the first arm 112 moved a crucible 108 into the receiving station 106 and Figure 7 shows the furnace 100 with the first arm 112 in a contracted condition.
In this embodiment the carousel 104 is moveable along its axis in upward and downward direction. Figure 6 shows the carousel in an upward position and Figure 7 shows the carousel in a downwards positions. The upward and downward movement of the carousel 104 is controlled such that the carousel 104 is in a downward position when the arm 112 moves a crucible 108 over a respective receiving station 106. The carousel 104 then moves to the upward position such that the crucible 108 is lifted off the arm 112 and is placed in the aperture of the receiving station 106. The first arm 112 then retracts. The second arm 114 and the carousel 104 operate in a corresponding manner for unloading the crucibles 108.
Coupled to the furnace 100 is a conveying system from which crucibles 108 are positioned by the second arm 114 and which delivers crucibles 108 to the first arm 112 in a sequential manner. A person skilled in the art will appreciate that such a conveying system may take any suitable form and such systems are known in the art.
The housing 102 of the furnace 100 has an access port 116 at a side portion through which the arms 112 and 114 move the crucibles 108. The access port 116 has an access door (not shown) that can be remotely opened and closed when the first or second arms 112, 114 are in use. In variations of the described embodiment the furnace 100 may also comprise more than one carousel 104 and the carousels may be positioned over one another and arranged for rotation about a common axis driven by the drive 105. In this case the furnace 100 comprises a suitable means for moving all carousels up and down such that the arms 112 and 114 are able to operate as described above. Alternatively, the furnace 100 may also comprise more than one mechanism for moving the crucibles 108 and the mechanisms may be stacked on top of one another in the same manner as the carousels.
The furnace 100 comprises control electronics (not shown) that is arranged to allow automated operation of the furnace 100. Further, the furnace 100 comprises temperature sensors (not shown) and is arranged such that a user can select a temperature and a time for the heat treatment. These parameters may be preselected and the control electronics is arranged to operate in accordance with the pre-selected parameters in an automated manner. Consequently, the control electronics controls operation of the drive 105, a heater (not shown), the carousel and the first and second arms 112 and 114. The control electronics is also arranged to control operation of the access door (not shown) at the access port 116 when the first or second arms 112, 114 are in use. In one specific embodiment a drive shaft of the carousel 104 is arranged for imparting an oscillating movement about the axis of the carousel 104 and is also controlled by the control system.
Referring now to Figure 8, a flow chart of a method 800 of preparing fused (homogenised) samples for sample analysis in a furnace in accordance with a specific embodiment of the present invention is now described. For example, the furnace may be the above-described furnace 100. The method 800 comprises the initial step 802 of providing a plurality of crucibles with samples to a mechanism for moving the crucibles. Further, the method 800 comprises step 804 of moving the crucibles in sequence to respective receiving stations of a carousel of the furnace using the mechanism for moving the crucibles. Step 804 moves the crucibles through an access port in a side wall of the furnace. Further, the method 800 comprises step 806 of rotating and oscillating the crucibles in respective receiving stations about an axis of the carousel while exposing the samples to heat treatment in the furnace. The heat is sufficient to cause melting of each sample. The method 800 also comprises step 808 of removing the crucibles with respective samples in sequence using the mechanism for moving the crucibles and positioning the crucibles on a conveyor for moving the crucibles away from the furnace.
Having described a specific embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments and that various changes and modifications could be effected therein by one skilled in the art without departing from the scope of the invention as defined in the appended claims.

Claims

A furnace for preparing fused (homogenised) samples for sample analysis, the furnace comprising:
a housing;

a heater arranged for heating an interior portion of the housing to a temperature sufficient for causing melting of each sample;

a carousel positioned in the housing, the carousel having a plurality of receiving stations for receiving crucibles containing respective samples, the carousel being arranged for rotating the crucibles about an axis when the crucibles are positioned in respective receiving stations; and

a mechanism for moving the crucibles relative to the respective receiving stations and relative to the housing to load and unload the carousel;

characterised in that the mechanism for moving the crucibles is arranged to move the crucibles in a direction that has a component perpendicular to the axis about which the carousel is arranged to move the crucibles; and

in that the housing has an access port in a side wall portion through which in use the crucibles are moved by the mechanism for moving the crucibles.
The furnace of claim 1 wherein the mechanism for moving the crucibles comprises a first arm having a portion for supporting a crucible and being arranged for contraction and extension along a length of the arm whereby the first arm is arranged such that the crucible can be moved between a receiving station of the carousel and a position that is remote from the carousel.
The furnace of claim 2 wherein the mechanism for moving the crucibles comprises a second arm for moving the crucibles with the respective samples and wherein the second arm has a portion for supporting a crucible and is arranged for contraction and extension along a length of the arm whereby the second arm is arranged such that the crucible with respective samples can be moved between a receiving station of the carousel and a position that is remote from the carousel.
The furnace of claim 3 wherein the first arm is arranged for positioning the crucibles into the receiving stations of the carousel and the second arm is arranged for removing the crucibles with the respective samples from the receiving stations.
The furnace of any one of the preceding claims comprising a control system that is arranged to control operation of the heater, the carousel and the mechanism for moving the crucibles in an automated manner and wherein the control system is configured to effect removal of a crucible with the respective sample.
The furnace of claim 5, wherein the control system is arranged to control the furnace such that the first arm in use positions a sequence of crucibles into a sequence of respective receiving stations and the heater subsequently heats the samples in the crucibles during rotation of the crucibles in the carousel, and wherein the control system is arranged to control the furnace such that the second arm removes the crucibles with respective samples sequentially from the receiving stations after completion of a predetermined heat treatment.
The furnace of any one of the preceding claims wherein the furnace is arranged to impart an oscillating motion to the samples in the crucibles when the crucibles are positioned in the receiving stations.
The furnace of claim 3 wherein the mechanism for moving the crucibles comprises an arrangement for lifting and lowering the crucibles relative to the first and second arms.
The furnace of any one of the preceding claims wherein the housing comprises an access port that has an access door that is arranged for closing the access port.
A method of preparing fused (homogenised) samples, the method comprising the steps of:
providing a plurality of crucibles with samples to a mechanism for moving the crucibles;

moving the crucibles in sequence to respective receiving stations of a carousel of a furnace using the mechanism for moving the crucibles;

rotating the crucibles in respective receiving stations about an axis of the carousel;

exposing the samples to heat treatment in the furnace to melt the samples in the crucibles; and subsequently

removing the crucibles with the respective samples in sequence using the mechanism for moving the crucibles and positioning the crucibles on a conveyor for moving the crucibles away from the furnace.;
characterised in that the step of moving the crucibles comprises moving the crucibles in a direction that is transversal to an axis of rotation of the carousel and through an access port in a side wall of a housing of the furnace and

in that the step of removing the crucibles with the respective samples comprises moving the crucibles in a direction that is transversal to an axis of rotation of the carousel and typically through an access port in a side wall of a housing of the furnace.
The method of claim 10 comprising using a control system to effect removal of a crucible with the respective sample.
The method of claim 10 or 11 wherein the step of moving the crucibles comprises using a first arm having a portion for supporting a crucible and being arranged for contraction and extension along a length of the arm whereby the crucible is moveable between a receiving station of the carousel and a position that is remote from the carousel; and
wherein the step of removing the crucibles with the respective samples comprises using a second arm that has a portion for supporting a crucible and is arranged for contraction and extension along a length of the arm whereby the crucibles with the respective samples are moveable between a receiving station of the carousel and a position that is remote from the carousel.
The method of any one of claims 10 to 12 comprising imparting an oscillating motion to the samples in the crucibles during fusion when the crucibles are positioned in the receiving stations.