WO2001038847A1

WO2001038847A1 - Sample testing

Info

Publication number: WO2001038847A1
Application number: PCT/AU2000/001433
Authority: WO
Inventors: Nicholas Bradshaw
Original assignee: Nicholas Bradshaw
Priority date: 1999-11-25
Filing date: 2000-11-24
Publication date: 2001-05-31
Also published as: CN1425129A; AUPQ422299A0; CN1219200C; ZA200204137B

Abstract

Method and apparatus for producing a specimen bead in a mouldible (9) for future analysis wherein a halogen gas is passed over the surface of the specimen whilst molten to increase surface tension thereof thus enabling the bead to be released from the mouldible. A furnace (1) has a cradle (8) to support the mouldibles (9) and an injector (12) delivers halogen gas through nozzle 17. Alternatively, a halogen source may be located in the cap or lid of the mouldible.

Description

SAMPLE TESTING

This invention relates to sample testing, more particularly to the preparation of samples for analytical testing.

In the preparation of mineral samples or processed mineral samples for testing, the mineral sample is prepared by mixing a prescribed amount of the sample to be treated, either by volume or weight, with a flux, such as lithium tetraborate or lithium metaborate and heating the mixture in a furnace to produce a sample which can then be analysed. The samples placed in a carbon, gold or platinum mould or mouldible is then heated in a furnace. However there is a serious problem in that the molten mixture adheres to the inner surface of the mould or mouldible and it is not possible to form and release a bead or sample specimen for subsequent analysis. To overcome the problem, mould release agents, or agents to increase the surface tension of the molten material are introduced into the specimen. However these substances are thus a pollutant in the specimen and thus can be a serious detriment to the correct analysis of the specimen.

Also it is often necessary to slowly agitate the specimen while being heated to ensure thorough mixing of the material and the flux, and also if the molten specimen adheres or tends to adhere to the inner wall of the mould or mouldible, bubbles can be formed in the specimen which thus seriously effect the microscopic, x-ray and other examination of the specimen.

As noted above use of the mould release agents in the preparation of fusion bead X.R.F. samples is well known. The agents used are generally compounds of the halogen group of elements, it is the halide that is the active ingredient, ie, Fluorine, Chlorine, Bromide, and iodine. These agents were added to the fusion as a compound, eg, Sodium Bromide, Ammonium Iodide, Potassium Iodide, and Hydrobromic Acid etc.

However the mould release agent would then become part of the sample, and in some cases react with the sample, often in an uncontrolled way, resulting in unsatisfactory modification of the sample and consequent inaccurate analysis. Thus it is an object to provide a method and apparatus for overcoming one or more of the problems associated with the prior art.

Trials were conducted with the addition of pure halogens as a gas to the surface of the sample during the heating and/or melting, and/or mixing and/or cooling of the fusion bead, and found that, surprisingly, applied in this way the halogens do not become part of or react with the sample.

Tests with iodine were conducted and two systems of providing the iodine gas were trialed. One system generated iodine gas from solid iodine, and the gas was delivered to the sample surface during heating and mixing.

The second system provided iodine gas to the surface of the fusion bead as it was cooling.

Both systems are satisfactory and depending on the sample being tested, either one or both of the systems can be employed on a sample.

Thus there is provided according to the invention a method of producing a specimen of a material to be tested and a flux, said method including the step of applying a halogen in gaseous form to the surface of the specimen either during the melting process in the furnace and/or after removal from the furnace whilst the specimen is in molten form.

Also there is provided according to the invention a furnace for producing a specimen for future testing, said furnace having means to receive a mouldible containing a material to produce a specimen, heating means in the furnace and means to inject or pass a halogen gas across the surface of the molten or partially molten specimen to increase the surface tension of the molten material whereby a specimen bead is produced which does not adhere to the inner wall of the mouldible.

Preferably the halogen is iodine in gaseous form.

Preferably the mouldible is slowly agitated, and the iodine gas is periodically passed over the surface of the molten material. In another form of the invention there is provided the step of applying the iodine gas to the surface of the molten material in a mouldible after the mouldible is removed from the furnace.

Preferably the invention includes the step of removing the mouldible from the furnace and adding iodine in solution or solid form to a portion of the inner surface of a cap and placing the cap on the mouldible whereby the heat of the molten specimen and mouldible vaporises the iodine which then contacts the surface of the molten specimen to increase the surface tension thereof.

In order to more fully describe the invention reference will now be made to the accompanying drawings in which:-

Figure 1 is a perspective view of a furnace which can be used in the invention,

Figure 2 is a further view of portion of the furnace with the lid raised,

Figure 3 is a cross sectional view of one form of iodine injector,

Figures 4(a), 4(b) and 4(c) are a cross sectional view of a further form of injector,

Figure 5 are views of a mouldible and cap,

Figure 6 is a view of a further form of cap to be placed over a mouldible,

Figure 7 is a cross sectional view of the cap on a mouldible,

Figure 8 is a view of a further form of injector, and

Figure 9 is a cross-sectional view of the injector of Figure 8.

Referring firstly to Figures 1 and 2, there is shown a furnace 1 with lid 2 to close the interior 3 of the furnace which is heated, in this instance by electrical elements (not shown). The lid is supported by a parallel linkage 4 about a pivot 5, so that the lid seats flush on the upper surface 7 of the furnace. Handles 6 are provided so that the lid can be raised and lowered. The interior of the furnace includes a cradle 8 which can hold a number of mouldibles 9, the cradle being supported on pivot axles 10, one of which is driven by a motor and crank so that the cradle can slowly oscillate or rock so that the sample is mixed during the heating and melting phase of the sample. The furnace includes stands 11 in which the mouldibles can be placed during the cooling phase of the sample.

The furnace includes an injector 12 to deliver a halogen in the form of iodine gas to the sample. One form of injector is shown in a cross sectional view in Figure 3. Solid iodine can be placed in a trough 13, the iodine being heated by an electrical element 14 supplied with electrical current through conductor 15. An air supply is supplied through air line 16, the air thus blowing the gaseous iodine through nozzle 17 into the top of the mouldible 9. The injector 12 includes a reflector 18 positioned above the electrical element 14.

As noted above the cradle is oscillated or rocked, and when the mouldible open top is facing the nozzle, a control unit (not shown) energises the electrical element to vaporise a portion of the iodine and causes a puff of air to pass over the surface of the iodine collecting the gas and pass the gas into the open top of the mouldible and onto the surface of the sample.

Figures 4(a) and 4(b) show a further form of injector 26 which is of simpler construction with greater ease of adding the iodine to the injector. The injector 26 has a body 27 with an open bottom closed by a boat or trough 28, an inlet connection 29 provided for the supply of the injecting air. The body supports the electrical element 30 and electrical connection terminals 31 and 32. A reflector 33 is positioned above the element 30 to direct the heat of the element downwards to the iodine. The iodine is placed in the boat or trough 28 which can be fastened in position by fasteners passing through the holes 34, a sealing ring 35 sealing the boat or trough 28 to the body 27.

Figures 5(a) and 5(b) illustrate a second embodiment of the invention showing the mouldible 9 and a cap or lid 19 to be placed over the mouldible 9. The under surface of the lid has a liquid retaining member sponge or gauze 20 to retain a small quantity of iodine. The lid has a rim 21 to locate on the mouldible 9 and a flange 22 to rest on the top flange of mouldible. The lid or cap has a handle 2 formed by spaced discs 24 for cooling purposes, the discs being separated from the flange 22 by insulating material 25.

The lid or cap is placed on the mouldible on removal from the furnace, and the iodine in the metal sponge is vaporised by the residual heat in the mouldible and sample, the iodine gas being trapped in the mouldable as the sample cools and until the lid is removed.

Figure 6 shows a further form of cap 36 for the mouldible 9. The cap 36 has two portions an inner cap 37 and an outer cover cap 38. The two portions are separated by an air gap 39 while being joined at their upper end by a stud 40 on a metal sponge 41. The metal sponge 41 abuts the upper end of the inner cap with the stud passing through a hole in the inner cap and through the outer cover cap, a nut 42 holding the two portions together.

The inner cap has a rim portion 43 to enter the mouldible and an upstanding flange 44. The end 45 of the outer cap terminates above the flange 37 to provide a gap 46. The outer cover cap has an air inlet 47 leading to an air jet 48. In use the cap is placed over the mouldible and the air supply connected to the air inlet. The air flows around the space between the inner cap and the cover cap thus effectively insulating the outer cap from the inner cap so that when the cap has to be removed the outer cap can be grasped and the cap removed.

A further form of injector 50 is shown in Figures 8 and 9. The injector 50 includes a body portion 51 to which is attached a vapourising chamber 52 and a nozzle 17. The chamber 52 includes an air injection aperture 53 and air supply hose 54. An electrical element 55 is connected to electrical supply wires 56. The injector 50 has a locking collar 57 and stud 58 whereby the injector can be mounted in a furnace. The end of the chamber 52 is closed by a plug 59 mounting the heating element 55 and having nipple 60 to which the air hose 54 is attached. The plug 59 is removable being retained in position by a locking stud 6. In use the plug is removed, a quantity of iodine crystals is placed in the bottom of the chamber and the plug replaced. Preferably the heater element is a small lamp which provided sufficient heat to vapourise the iodine crystals. By using a lamp the heating element is protected from any corrosive effects of the iodine gas. Thus it can be seen that there is provided by the invention a system where there are produced beads for analysis which are free from bubbles and which are not contaminated by the material the mould release agent. The release agent such as the halogen gas is applied to the surface of the molten specimen during the molten stage , and this can be either during the heating and mixing of the specimen or to the surface during the cooling of the sample on removal from the furnace.

Although various forms of the invention have been described in some detail, it is to be realised that the invention is not to be limited to the specific details but can include variations and modifications falling within the spirit and scope of the invention.

1 A method of producing a specimen of a material to be tested and a flux in a mouldible, said method including the step of applying a halogen in gaseous form to the surface of the specimen in the mouldible either during the melting process in the furnace and/or after removal from the furnace whilst the specimen is in molten form to reduce the surface tension of the molten specimen.

2. A method as defined in Claim 1 wherein the halogen is gaseous iodine.

3 A furnace for producing a specimen for future testing, said furnace having means to receive a mouldible containing a material to be tested and a flux to produce a specimen, heating means in the furnace and means to inject or pass a halogen gas across the surface of the molten or partially molten specimen to increase the surface tension of the molten material whereby a specimen bead is produced which does not adhere to the inner wall of the mouldible.

4 A furnace as defined in Claim 3 wherein the halogen is iodine in gaseous form.

5 A furnace as defined in Claim 3 or Claim 4 including drive means to slowly agitate the specimen in the mouldible.

6 A furnace as defined in any one of Claims 3 to 5 and including means to periodically pass a halogen gas over the specimen.

7 A furnace as defined in Claim 6 wherein the means to periodically pass a halogen gas over the specimen includes an injector.

8 A furnace as defined in Claim 7 wherein the injector includes heating means to vapourise iodine, and means to supply a periodic flow of air through the injector.

9 A method as defined in Claim 1 including the step of removing the mouldible from the furnace, and applying the halogen gas to the surface of the

Claims

specimen in the molten state.

10 A method as defined in Claim 9 including the step of applying the solid or liquid halogen substance to the interior of a cap, and placing the cap on the mouldible wherein the heat in the mouldible and specimen vapourises the halogen substance over the surface of the specimen.

11 A method as defined in any one of Claims 1 , 2, 9 and 10 wherein the halogen gas is selected from iodine, flouring, chlorine, and bromide.