Specimen preparationSpecimen preparation XRF Grine Specimen... · 2010-08-27 · products made from...

Specimen preparationSpecimen preparationSpecimen preparation Specimen preparation XRFXRFXRFXRF

Patrick GrinePatrick GrineVesuvius, USAVesuvius, USA

ICDD Conference 2010ICDD Conference 2010ICDD Conference 2010ICDD Conference 2010

Patrick Grine, Vesuvius USAPatrick Grine, Vesuvius USA

Vesuvius is a world leader in the design, engineering manufacture and delivery ofengineering, manufacture and delivery of refractory products, systems and services for high technology industrial applicationsfor high-technology industrial applications.


Applications:

• Refractories and systems used to control, y ,regulate and protect the flow of steel in the continuous casting process:g p


Flow Control refractories and systems

- Alumina graphite isostatically-pressed tubes, nozzles and stoppers.


These products are used for flow

l ti f llregulation of all grades of steel in continuous casting.



- Slide-gate and tube changer t d l tsystems and plates.


Slide gates provide precise flow control at constant casting speed in any length of cast.


Tube changers are used for long sequence casting and increased safety in extended stopper-nozzle operations.



- Gas-purging plugs and temperature-control devices. p


During the secondary metallurgy process, after chemistry and temperatureDuring the secondary metallurgy process, after chemistry and temperature adjustments, molten steel is stirred in the ladle to make it homogenous. This is done by means of gas purging plugs at the bottom of the ladle, which allows inert gas to be blown in the molten steel.


Applications:

• Refractories for the foundry industry, such as crucibles, filters, stoppers and dedicated linings.


Filters provide cleaner metal and better casting quality in the aerospace, automotive, rail transport and heavy machinery industries.


Applications:

• Fused-silica refractories for flat glass manufacture and the melting of polycrystalline silicon.


Applications:

• Refractories linings for high-temperature, g g p ,heavy-duty industrial applications.


Vesuvius is present in 30 countries on 5 continents, with 50 manufacturing units, 7 R & D centres and numerous sales agencies, together employing over 9000 people.


What are Refractories?What are Refractories?

“ A refractory is a material resistant to fusion A refractory is a material resistant to fusion or other effects of high temperatures. Such refractories, in addition to being gresistant to heat, must also withstand varying amounts of other destructive f i i h idforces in service, such as rapid temperature changes, attack by various chemicals heavy stresses under load atchemicals, heavy stresses under load at high temperatures, abrasion and physical abuse”


abuse .


Commercial refractories with fewCommercial refractories, with few exceptions, are oxides or combinations of oxides of chemical elementsoxides of chemical elements. By this means refractories fall in four major groups: Alumina Silica Silica Basicgroups: Alumina-Silica, Silica, Basic, and Special Refractories.V i i l d d iVesuvius mainly produces and services the Alumina-Silica and Basic refractories.



Alumina-Silica materials vary in refractoriness, the higher the alumina content (Al2O3) thethe higher the alumina content (Al2O3) the greater the refractoriness. They exhibit a long melting-temperature range

t di f th t t t hi h li idextending from the temperature at which liquids first form to that at which the entire mass is molten. Alumina-Silica refractories, also called “Acid Refractories”, are those that react with basic slags and fusions. These include silica bricksslags and fusions. These include silica bricks (dinas), fireclay, and other aluminosilicate refractories.



Basic refractory materials comprise theBasic refractory materials comprise the products made from magnesite or chrome oreore. As a group, basic materials --- in contrast to the alumina silica group exhibit muchto the alumina-silica group --- exhibit much greater refractoriness, and better resistance to chemical attack of slags andresistance to chemical attack of slags and metallic oxides.


Acidic & Basic Compounds, Solution Acidic & Basic Compounds, Solution Ch i tCh i t

• Traditional solution chemistry:

ChemistryChemistry

y• Hydrochloric acid in water dissociates to form a

hydrogen ion, also called a proton, and its chloride counter ion:counter ion:

• HCl + H2O → H+ + Cl- + H2O• Sodium hydroxide in water dissociates to form a hydroxyl

i l it di t iion plus its sodium counter ion:• NaOH + H2O→ Na+ + OH- + H2O• Hydrochloric acid reacts with sodium hydroxide in waterHydrochloric acid reacts with sodium hydroxide in water

to form common table salt plus a molecule of water:• HCl + NaOH → NaCl + H20 + Δ


Acidic & Basic Compounds, from a Acidic & Basic Compounds, from a R f t P tiR f t P tiRefractory PerspectiveRefractory Perspective

Acidic Compound: A compound that can p pcontribute silica to a reaction in a high temperature environment.Basic Compound: A compound that can acceptBasic Compound: A compound that can accept or react with silica in a high temperature environment.Th lt i ll d th t hThe result is generally a compound that has a melting range well below either of the reactants.Therefore, acidic refractories are generally used e e o e, ac d c e acto es a e ge e a y usedfor industrial processes that produce acidic slags and basic refractories are generally used for industrial processes that produce basic slags


industrial processes that produce basic slags.

Acidic & Basic CompoundsAcidic & Basic Compoundspp

Acidic Compounds Include:Acidic Compounds Include:Silica, SiO2 (the big trouble maker)Al i Al O ( k id l t bl )Alumina, Al2O3 (weaker acid, less trouble)

Basic Compounds Include:Magnesia MgOMagnesia, MgOLime, CaO


“V Ratios” Means by Which to Index Slag “V Ratios” Means by Which to Index Slag A idit / B i itA idit / B i itAcidity / BasicityAcidity / Basicity

• The “V Ratio” in its simplest form:p• “V Ratio” = (Wt % CaO)/(Wt % SiO2)• If greater than 1, slag is basic

If l th 1 l i idi• If less than 1, slag is acidic• More complex forms of this are used at various

operations to more accurately describe the situation.• For Example• “V Ratio” = (Wt % CaO + Wt % MgO)/(Wt % SiO2

+ Wt % Al O )+ Wt % Al2O3)• Remember, any “V Ratio” is an index, not an absolute

value.


What are Refractories?What are Refractories?In the processing of metals, cements, glass and other materials it is common for the furnace charge, that is, the material being processed to react chemicall and ph sicall ith the refractorprocessed, to react chemically and physically with the refractory lining.

In many furnaces the way in which the charge materials react withIn many furnaces the way in which the charge materials react with the refractories in the lining depends on the chemical nature of the reactants, that is, whether the lining and charge are chemically acidic or basic.

Because acids react vigorously with bases, the materials would be operating in ideal conditions for early failure due to high temperatures and fast chemical reaction rates. Charge-lining reactions are an important section in refractories technologyreactions are an important section in refractories technology.


Analysis of RefractoriesAnalysis of Refractoriesyy

Analysis of refractories in the Vesuvius’s yBettsville laboratory has evolved into mainly being done by X-ray spectroscopy.

Quantitatively, the majority of analyses, are completed by x ray fluorescencecompleted by x-ray fluorescence.

Due to a certain level of accuracy and efficiencyDue to a certain level of accuracy and efficiency needed, “fusion” XRF analysis has taken precedence to “pressed pellet” XRF analysis.


Vesuvius’s use and necessity of fusion Vesuvius’s use and necessity of fusion d ll t ( h li bl )d ll t ( h li bl )over pressed pellets (when applicable)over pressed pellets (when applicable)

Vesuvius reasons for use of fusionVesuvius reasons for use of fusion versus pressed pellet methodology is driven by Laboratory Operation Policydriven by Laboratory Operation Policy and Quality:

Laboratory Operation PolicyA) “As routine as possible”



What is meant by “routine” for Vesuvius? L t t f- Low cost to perform

- Does not take a long time- Limited change of methodology



B) “Quality” requirementB) Quality requirement

D fi d b t f tiDefined by two factions:1) Engineers2) Analytical Laboratory



Engineer’s requirement:Engineer s requirement:Alumina-Silica samples

If t ti f l t i 10%If concentration of element is > 10%, +/- 2% relative error allowed.If concentration of element is 1-10%, +/- 5% relative error allowed.If concentration of element is < 1%, +/-10% relative error allowed.



Basic samplesBasic samples

10 % l ti i ll d f ll l10 % relative error is allowed for all samples



Analytical Laboratory’s requirement:Analytical Laboratory s requirement:

) R d f th d hila) Ruggedness of method while maintaining accuracy of resultsb) 99.79 % confidence level result requirement in Quality Assurancec) Maintenance of method



In trying to fulfill these requirements forIn trying to fulfill these requirements, for Vesuvius, fusion methodology took precedence over pressed pelletprecedence over pressed pellet methodology.

Why?



a) Considerable savings ina) Considerable savings in materials compared with what had previously been done usinghad previously been done using pressed pellet methodology



The current two fusion methods usedThe current two fusion methods used cover > 95 % of the XRF analyses performed This was a reduction from 33performed. This was a reduction from 33 previous methods of which almost all utilized pressed-powder methodologyutilized pressed powder methodology.



Another reason:Another reason:

b) C id bl i i tib) Considerable savings in time.

The current two fusion methods each analyze a sample in less than 5 minutes. Prep time for

h l b t 15 i teach sample averages about 15 minutes. Clean-up is quick with no residual sample to dispose of except the analyzed bead


dispose of except the analyzed bead


Historically, most of the chemical analysesHistorically, most of the chemical analyses at Bettsville, was done by ICP (Inductively Coupled Plasma) Emission Spectroscopy.

Most of the Vesuvius products require p qanalyses at concentration ranges of 0.1 % or greater. It was not efficient to dissolve a

lid l d dil b f i ld bsolid sample and dilute, before it could be brought into the range of the instrument.



Direct read of a fused bead was more logical!g



Final Reason:

c) Scope, for the operation of the lab, not to “allow each analysis to become a research project”each analysis to become a research project .

This meant efficiency and accuracy had to be rolled into one methodology. The knowledge and work needed to do pressed powder methodology did not allow the freedom necessary to stay within the “routine” y yboundaries.



C i f M th d-------------Comparison of Methods----------------



Considerations based on analytical sample presented Considerations based on analytical sample presented

Steps Fusion Pressed Powder 1. N/A Inhomogeneity

/A i l Si ff2. N/A Particle Size effects

3. N/A Incr. scattering power due to binder

4 N/A Incr. background radiation4. N/A Incr. background radiation due to binder

5. Stability of sample: very stable

Stability of sample: depends

6 S f l Di l ti S f l P d6. Successful - Dissolution Successful - Pressed

7. Analysis valid - Check Stds. pass All of the above controlled



Frequent changing or development ofFrequent changing or development of methodology would be considered taking us out of the realm of “routine” and moreus out of the realm of routine and more into continuous research. Trends noting the frequency of samplesTrends noting the frequency of samples needing new or a change of methodology does though eventually warrant the timedoes though eventually warrant the time allowed to complete this task.


Sample Preparation of Vesuvius’s Sample Preparation of Vesuvius’s A l ti l S lA l ti l S lAnalytical SamplesAnalytical Samples

Our preparation of raw materials, materials in process and finished products forin process and finished products for chemical analysis include two methods:

“Method A” and “Method B”



• Method A is a procedure for the preparation of “soft materials” (Basic) such p p ( )as periclase (MgO), MgO boat samples, periclase refractories, dead-burned p ,dolomite and dolomitic refractories, slags, high silica refractories and such materials gfor chemical analysis.



The sample for chemical analysis must be representative of the mass from which it isrepresentative of the mass from which it is taken. This is done by following proper sampling protocol to secure asampling protocol to secure a representative laboratory sample.



If th l t i 3/8 i h t i l itIf the sample contains >3/8 inch materials, it first must be passed through a jaw crusher t d i i t 3/8 i hto reduce sizing to <3/8 inches.



A i t l 50 f th l b t lApproximately 50 g of the laboratory sample is then riffled….



…and placed in a Bleuler mill



with a grinding ring and puckwith a grinding ring and puck.



Note !Note ! For dolomitic and any other materials that adhere to the grinding container 1or 2adhere to the grinding container, 1or 2 drops of ethylene glycol are added before grinding It is important no more than 2grinding. It is important no more than 2 drops are added.



After the grinding container is placed in theAfter the grinding container is placed in the mill, the sample is ground for two minutes. It must be noted here that some materialsIt must be noted here that some materials maybe ground for less than two minutes.

ALL MATERIAL MUST PASS A 200 MESH SCREEN FOR CHEMICAL ANALYSISSCREEN FOR CHEMICAL ANALYSIS.



The prepared sample for chemical analysisThe prepared sample for chemical analysisis then removed from the grinding container

d l d t lli l thand placed onto a rolling cloth….



the sample is then quickly placed in a…the sample is then quickly placed in a sample container to prevent the absorption of moisture and carbon dioxide. Theof moisture and carbon dioxide. The sample container is labeled and given to the chemistry analytical laboratory.y y y


Sample Preparation of Vesuvius’s Analytical Sample Preparation of Vesuvius’s Analytical S lS lSamplesSamples

• Method B is a procedure for the preparation of “hard” materials or minerals such as siliconhard materials or minerals such as silicon carbide, chromite, high-alumina (corundum), fused cast refractories, and refractories containing any of the above minerals, for chemical analysis.



Again, the sample for chemical analysis,must be representative of the mass frommust be representative of the mass from which it is taken and proper sampling protocol must be followed to secure aprotocol must be followed to secure a representative laboratory sample.



I thi th d ll t i l t fi t bIn this method all material must first be reduced to minus 20 mesh by using a l tt i il tplattner or similar mortar.



Approximately 50 g of this sample isApproximately 50 g of this sample is transferred to a rolling cloth. Magnetic iron contamination, introduced from primarycontamination, introduced from primary crushing, is removed by use of a magnet.



Th l i th l d i T tThe sample is then placed in a Tungsten Carbide (WC) Rotary Cup container with WC i di i d kWC grinding ring and puck.



The grinding container is placed in mill andThe grinding container is placed in mill and ground for 90 seconds.

Note! Some materials may take longer than 90 secondsthan 90 seconds.

The sample is then removed to a rollingThe sample is then removed to a rolling cloth and a approximately 5 g sample is removed


removed.


The 5 g sample is screened through a 200The 5 g sample is screened through a 200 mesh screen. Using a corundum mortar and pestle, the material that was left onand pestle, the material that was left on the screen is ground until all material passes the 200 mesh screen. p



H l f l t A l ¼ i h b i tlHelpful note: A clean, ¼ inch bristle brush with the bristles cut down, speeds

th iup the screening process.



Th 5 d l i thThe 5 g screened sample is then transferred to a properly labeled container

d h k til hand shaken until homogenous.



In order to insure the fusion, using the Lithium Borate flux is successful (i eLithium Borate flux, is successful (i.e., fusion of “oxides”), the laboratory sample is first weighed out into a platinumis first weighed out into a platinum crucible.



Th l b t l i th l d iThe laboratory sample is then placed in afurnace at 1025 ° C for two hours in order to “calcine” (oxidize) the sample.


Sample Preparation of Vesuvius’s Analytical Sample Preparation of Vesuvius’s Analytical S lS l

After calcining the laboratory sample for

SamplesSamples

After calcining the laboratory sample for two hours, the sample is cooled in a dessicator The sample is then weigheddessicator. The sample is then weighed into a “Bis” platinum fusion crucible at a ratio of 10:1 [flux:sample] using Lithiumratio of 10:1 [flux:sample] using Lithium Tetraborate.



The sample and flux is mixed using a spatula and then a mortar and pestle. The crucible, p ,containing the mixed sample, is then placed on an automatic “fluxer” to be fused. Predetermined programs have been entered into the controls of the fusion instrument specific for h f l b i f dthe type of sample being fused.



Th lt i f d b d t l t dThe result is a fused bead translucent andsymmetrically shaped.


In addition to XRF, other methods of In addition to XRF, other methods of l i i l b t i l dl i i l b t i l danalysis in our laboratory include:analysis in our laboratory include:


Other Methods:Other Methods:

• Wet Chemistry MethodsWet Chemistry Methods

- Used for specific analyses that have not yet- Used for specific analyses that have not yet been developed using other available means (i.e, current available instruments) or an ( , )alternative means, has not yet been afforded financially or it is still warranted as the best

h d il bl f dmethod available for our needs.



Hydrogen Evolution Method for Free Silicon Metal



• X-ray DiffractionX ray Diffraction- Qualitiative analyses

[picture 9]



• Inductively Coupled Plasma (emissionInductively Coupled Plasma (emission spectroscopy)

- Quantitative multi-element trace l & h k th danalyses & cross-check method.



• Atomic Absorption SpectroscopyAtomic Absorption Spectroscopy

Q tit ti t l f- Quantitative trace analyses for single elements & a cross-check

th dmethod.



• UV-Vis SpectrophotometerUV Vis Spectrophotometer

N t l l (NO PO- Non-metal analyses (NO3, PO4, SO4) Hach digestion setup.



• Leco CS 230Leco CS 230

C b ti l i f C d S- Combustion analysis for C and S.


Troubleshooting Product FailureTroubleshooting Product Failuregg

• The value of a refractory depends upon it’s ability to y p p yretain it’s original volume.

• As a refractory is exposed to operation the• As a refractory is exposed to operation, the refractory wears away with the result that the thickness and therefore the volume, is reduced.

• Refractories are reduced in volume by the processes of fluxing, peeling, spalling, g g gdisintegration, loss of strength and vaporization.


Troubleshooting Product FailureTroubleshooting Product FailureTroubleshooting Product FailureTroubleshooting Product Failure

Vesuvius’s approach in determiningh th t d t h f il dwhether or not a product has failed,

involves Physical Testing / Mechanical T ti d/ Ch i l T tiTesting and/or Chemical Testing supported by Optical analysis.


Troubleshooting Product FailureTroubleshooting Product Failure

1 The process usually starts with a product

gg

1. The process usually starts with a product complaint from a customer.

2 A sample is submitted The sample can2. A sample is submitted. The sample can be in the form of the actual product prior to service or it can be a sample obtainedto service or it can be a sample obtained from what is called “post-mortem” – a sample that represents the product aftersample that represents the product after it has been put into service.



3. After analyses have been completed, interpretation of the results is done in ainterpretation of the results is done in a collective manner by the technicians, analysts and engineersanalysts and engineers.



As mentioned previously the products

gg

As mentioned previously, the products Vesuvius mainly produce and service are Alumina-Silica and Basic productsAlumina Silica and Basic products. Also mentioned earlier was the effects of a “charge” and the resulting slag from thatcharge and the resulting slag from that charge, on the refractory.


High MgO basic gunning product

Slag Cup test showing compatibility of Slag Cup test showing compatibility of basic and non-basic refractories to slags

Alumino-silicate gunning productgunning product



Alumina-Silicate refractory products develop a problem when elements such as what Vesuvius

gg

problem when elements, such as what Vesuvius calls “The Big Five” (Al, Si, Fe, Ca, Mg) are present as oxides because they enter intopresent as oxides because they enter into various solid solutions.IN GENERAL, elemental Si and Fe are not a ,major issue. Elemental Al, Ca, and Mg become a issue because they are capable of reducing the oxides, thereby becoming oxides that enter into solid solutions.



For Example:



Most of these elements are only critical in their

gg

ynear absence.

0.20 % SiO2 contamination in a white, silica-free castable (like Criterion 92SR) will reduce the hot MOR (Modulus of Rupture) at 2700 F from 1000MOR (Modulus of Rupture) at 2700 F from 1000 psi to < 50 psi (essentially zero). This is because the silica forms a liquid at the grain boundaries and interferes with the bonding between refractory grains.



Alumina has the similar effect on extremelyhi h ili d t (lik H d M 97S)high silica products (like HydraMax 97S). More than roughly 0.5% Al2O3, will cause amassive melting at the service temperature.



Fe2O3 is an issue under reducing conditions,

gg

Fe2O3 is an issue under reducing conditions, primarily with carbon monoxide. CO will reduce Fe2O3 to Fe3O4 or FeO or 2 3 3 4ultimately, Fe, with the resultant increase in volume which causes “bursting” in the refractory. Products, like Vesuvius’s SurShot 85AX, used in blast furnace stacks, have a maximum limit of 1 0 % F 2O3 b i1.0 % Fe2O3 to prevent bursting.



Basic refractory products also suffer fromtt k f ll t f l tattacks from small amounts of elements.

Some are actually introduced through theapplication used to protect them.


Tundish Safety Lining

Cracks and irregularirregular surfaces

promote sticking of working

li i d k lllining and skull

Peeling safety lining due to alkali attackalkali attack



Failure of “Basic” products can also occur

gg

Failure of Basic products can also occur when not enough of a minor element is presentpresent.

In this instance the element sodium as anIn this instance, the element sodium, as anoxide, which is used as a binder in refractorylinings was lacking in the amount neededlinings, was lacking in the amount needed.



F a i l u r e d u e t o n o t e n o u g h b in d e r



Basic Products also involve the “Big Five”Basic Products also involve the Big Fiveanalysis requirements for a number of h i lchemical reasons :



1. Analysis for MgO is done to make sure the product contains the correct amount pof MgO needed for expected refractoriness.



2. Analysis for Al2O3 is performed because high amounts of alumina and silica canhigh amounts of alumina and silica can deteriorate basicity of the refractory.



3 T hi h t f F O t

gg

3. Too high amounts of Fe2O3 promotescorrositivity within the refractory.

The following photo shows the result of t hi h t f b th SiO d F Otoo high amounts of both SiO2 and Fe2O3in the slag.



S la g lin e a fter 3 0 h e a ts- H P 7 6



4. If CaO is in excess of required amounts, hydration can occur causing destructionhydration can occur, causing destruction of the refractory by expansion.


Example of failure due to hydrationExample of failure due to hydrationp yp y


Hydrated Furnace BlockHydrated Furnace Block


How Strong is Hydration?How Strong is Hydration?How Strong is Hydration?How Strong is Hydration?



The previous slide shows Basic gunning

gg

The previous slide shows Basic gunning mix that got in the metal legs of the gunning apparatus by falling into the top ofgunning apparatus by falling into the top of the legs. The gunning material hydrated after about a year The legs of the gun areafter about a year. The legs of the gun are about six inch square steel pipe.


In SummaryIn Summaryyy

1. Vesuvius’s assurance of product integrity di t t th l i i d fdictates the analysis required for determining any loss of this integrity.

2. Vesuvius’s scope, for laboratory l i i t th d fanalysis, incorporates the need for a

certain level of quality to be achieved and maintained without beingand maintained without being overburdened by expense and time.


In SummaryIn Summary

3. Vesuvius’s ability to maintain the integrity

yy

3. Vesuvius s ability to maintain the integrity and quality of it’s products starts with the ability to properly prepare “complaint” y p p y p p psamples for analysis.

4. Fusion methodology, used in conjunction gy jwith x-ray fluorescence analysis, allows Vesuvius laboratories to provide the i f ti d d t k th d iinformation needed to keep the edge in the refractory market.


THANK YOU !


Specimen preparationSpecimen preparation XRF Grine Specimen... · 2010-08-27 · products made from...

Documents

Transcript of Specimen preparationSpecimen preparation XRF Grine Specimen... · 2010-08-27 · products made from...