Total versus incomplete digestions and selective leaches – Richard Holdsworth, Intertek Genalysis
Summary
TLDRこのビデオスクリプトでは消化プロセスとその分析プロセスへの適合について説明しています。まず、サンプルの受入と登録、次にサンプルの準備が行われ、その後消化に進みます。消化は、乾燥した同質のパルプを作成し、それを分析機器にフィードする必要がある理由は、乾燥したパルプでは機器が動作しないからです。消化方法には、完全消化と不完全消化があり、それぞれ異なる要素の回収率をもたらします。また、安全に関する注意点も触れられており、消化方法には危険性があると同時に、安全が最も重要な懸念事項であると強調されています。
Takeaways
- 🧪 试験室の消化プロセス:消化は分析プロセスに重要な位置を占めており、サンプルを均一な溶け出しに変える必要があります。
- 🔍 消化方法の種類:完全消化と不完全消化(部分消化)があり、完全消化は消化方法に依存しない一方、不完全消化は消化条件によって結果が変わる。
- ⚠️ 安全に関する注意:消化過程においては、特に過chloric酸など危険な化学物質を使用する際には火災や爆発のリスクがあることを意識する必要があります。
- 🔬 消化方法の選択:様々な消化方法(例えば、4酸消化、3酸消化、Aqua Regia消化など)があり、それぞれの方法は特定の要件に基づいて選択されます。
- 📉 不完全消化の限界:不完全消化では、一部の元素が適切に抽出されない可能性があり、比較分析を行う際には注意が必要。
- 🌟 火試金消化:貴金属を含む鉱石の分析に用いられ、非常に頑丈で信頼性の高い方法であるが、サンプルサイズが大きくなると分散誤差が小さくなる。
- 💧 浸出法:低レベルの分析や土壌、川底沈殿物の分析に適しており、非常に低い検出限を持つ。
- 🔥 融解消化:総量分析に適しており、頑丈な元素を含む鉱物に対する有効な方法で、消化後の溶けた物質を酸で抽出する。
- 📊 XRF融解:X線蛍光分析(XRF)のための融解消化は、物理的な影響を排除し、分析の正確性を高める。
- 📈 品質管理(QC):消化プロセスを適切に管理し、適切な基準物质を使用してプロセスの正確性を検証する必要がある。
Q & A
消化とは何であり、分析プロセスにどのように関与しますか?
-消化は、分析実験においてサンプルを適切な状態に変えるプロセスです。消化は、サンプルを溶液や融剤に変えることで、分析機器が測定できる形にします。
サンプル消化に必要な理由は何ですか?
-サンプル消化は、分析機器が乾燥したサンプルを測定できないため必要です。消化によりサンプルが溶液や融剤に変わり、測定が可能になります。
完全消化と不完全消化の違いは何ですか?
-完全消化は理性的手法であり、消化方法に依存しない結果を得られます。一方、不完全消化は経験的手法で、消化条件によって結果が変わる可能性があります。
消化方法の違いがサンプル分析にどのような影響を与える可能性がありますか?
-消化方法の違いは、特定の元素の抽出量に影響を与える可能性があり、結果の比較において注意が必要です。
鉱山現場での消化実験においてはどのような安全上の配慮が必要ですか?
-鉱山現場では、過chloric酸による煙や火災、爆発のリスクに加えて、特殊な抽出システムが必要とされます。また、熱源や融剤の危険性にも注意が必要です。
4酢酸消化とは何であり、どのような特徴を持っていますか?
-4酢酸消化は、過chloric酸、硝酸、HF、HCLを用いた消化方法です。硫化物を硫酸塩に変え、硫黄を保持することができます。
3酢酸消化はどのような特徴を持っていますか?
-3酢酸消化はHFを除外した消化方法で、多くの硫化物、氧化物、炭酸塩を効果的に消化できますが、シリカットの一部は消化しません。
Aqua Regia消化はどのような特徴を持っていますか?
-Aqua Regia消化は、硝酸と塩酸の混合物を使用し、多くの矿物種を溶解することができます。貴金属を含む多くの元素を抽出するのに適しています。
固体浸出法とはどのような分析手法ですか?
-固体浸出法は、低レベル分析に適した手法で、土壌、川底堆积物などのサンプルから金属イオンを抽出します。
消化プロセスにおけるQCとは何を意味していますか?
-消化プロセスのQCとは、品質管理を意味し、消化プロセスが正しく行われ、必要な元素が適切に抽出されることを確認するプロセスです。
火試金術とはどのような分析手法ですか?
-火試金術は、貴金属を抽出するための伝統的な手法で、サンプルを鉛と共に加熱し、貴金属を集約して測定します。
XRF融合消化とはどのような分析手法ですか?
-XRF融合消化は、サンプルをガラス状に融合させ、X線蛍光分析を用いて元素を測定する手法です。物理的および化学的效果を排除し、正確な分析結果を得ることができます。
Outlines
🔬 分析プロセスと消化方法の概要
第1段落では、分析プロセス全体の概要と、サンプルの消化がその中でどの位置づけにあるかが説明されています。消化とは、分析機器にサンプルを投入する前に、乾燥させた均質なパルプを作るプロセスです。消化は、機器に干したパルプを直接投入できないため、サンプルを溶液や融剤に変える必要があるとされています。また、消化方法には完全消化と不完全消化があり、完全消化は理論的手法として結果が消化方法に依存しない一方、不完全消化は経験則的手法で結果が消化条件に依存する点が強調されています。
🧪 消化方法の種類とその特性
第2段落では、様々な消化方法について詳しく説明されています。4酸消化は硫化物を硫酸塩に変え、ほとんどの矽酸塩を溶かすことができるが、いくつかの鉱物には抵抗があるとされています。3酸消化はHFを除外し、より安全性が高いとされていますが、矽酸塩を部分的に溶解し、硫化物鉱石に対する効果が優れている点が特徴です。Korea消化はニトリック酸と塩酸の混合物で、多くの鉱物種を溶解し、貴金属を含むが、矽酸塩や難溶性酸化物を効果的に処理できないことが指摘されています。また、浸出と呼ばれる技術も紹介されており、これは低レベルの分析に適しており、非常に低い検出限を持つとされています。
🌋 埋没鉱床と消化方法の応用
第3段落では、埋没鉱床におけるイオンの移動と、その分析手法について説明されています。分析の対象は基質の化学ではなく、表面に付着した外来イオンと微粒子であるとされています。様々な分析手法が応用されており、それらは表面に反応しやすい場所にイオンが集まるという仮説に基づいています。また、融剤消化は総量分析が可能で、難溶性元素にも対応できるという利点がありますが、融剤による分析の妨げになる金属の放出や、特定の元素の分析が困難になるという欠点もあります。XRF融剤は物理的な影響を排除し、より正確な分析が可能になるという利点を持ちます。
📊 分析品質の確保とQCの重要性
第4段落では、分析品質の確保とQC(品質管理)の重要性が語られています。様々な消化方法における元素の回復率についてのグラフが紹介されており、Korea消化では希土類はより抽出が困難であることが示されています。また、QCを行っている場合でも、消化プロセスが特定の成分を処理できない場合には、多くの失敗を経験する可能性があると警告されています。最後に、消化方法が正しく選択され、QCが適切に行われることが分析の信頼性を保証する上で欠かすことができないと結び付けられています。
Mindmap
Keywords
💡消化
💡総消化
💡部分消化
💡分析プロセス
💡溶け出し物
💡安全
💡酸消化
💡韓式消化
💡溶け出し物分析
💡選別消化
💡融合消化
💡XRF融合
💡ファイアアサイ
💡品質管理
Highlights
Sample digestion is a crucial step in the analytical process of an image laboratory.
Digestion methods are essential as instruments cannot process dry, heterogeneous samples.
Total digestions are rational methods with results independent of the digestion process used.
Incomplete or partial digestions are empirical methods, with results dependent on digestion conditions.
Different labs may have varied recipes for digestion, leading to different results for elements.
Safety considerations are paramount, especially with hazardous chemicals like perchloric acid.
Four-acid digestion is a staged process involving perchloric, nitric, hydrofluoric, and hydrochloric acids.
Hydrofluoric acid (HF) dissolves most silicates, converting samples into soluble perchlorate forms.
Three-acid digestion omits HF, is more aggressive, and effective against sulfide ores.
Aqua Regia digestion, a mix of nitric and hydrochloric acid, dissolves a wide range of mineral species and precious metals.
Aqua Regia is not effective against silicates and refractory oxides like rutile and ilmenite.
Solid leach two-tops is suitable for low-level analysis of soil, stream sediments.
Leach is an accelerated solid leach for gold ores to determine the sun audible gold in the sample.
Acid soluble copper and cyanide soluble copper are partial empirical techniques with different recovery rates.
Fusion digestions guarantee total dissolution, suitable for refractory elements and factory minerals.
Different types of fusion digests have their own advantages and limitations.
XRF fusions eliminate physical effects and provide a total analysis, simplifying corrections.
Fire assay is a traditional method for concentrating precious metals with quantitate recovery.
Nickel sulfide collection for assay can analyze a wider range of elements including osmium, iridium, rhodium, and ruthenium.
QC checks should be conducted based on what the digestion process can and cannot achieve.
Transcripts
well thanks Helen yeah I'm going to talk
about digestions and different types of
digestion and where they fit into the
analytical process quick curl overview
of the generalized process flow of an
image laboratory and where sample
digestion actually fits into that first
of all as Helen just to reiterate what
Helen said sample receipts and
registrations first then we have sample
preparation and the product of sample
preparation is a dry fine homogeneous
pulp then we have sample digestion feed
it into an instrument and do your QC why
do we do sample digestion simply because
the instruments we use commonly in a
laboratory you cannot feed them dry on
homogeneous pots and we have to
generally get it into a solution or in
the case of XRF we make called fusion
disks or gloss beads okay what are the
implications of using total and
incomplete methods or partial methods
well total digestions are what are known
as rational methods and essentially the
results are independent of the digestion
method used whereas the incomplete or
partial digests are empirical methods
and this is very important that we
remember this the results are dependent
on the conditions of the digest if you
hit it harder you're going to get more
out if you get all of it out okay you've
got all of it out you can't get any more
but there are lot of elements that you
can hit hard and you can hit not so hard
and you can get different amounts art
and they're very many variations on the
sound digestion take for example at
Korea a lot of labs out there a lot of
companies doing at Korea digestions and
they all have different recipes they've
got different recipes they're going to
get different numbers for a lot of the
elements and you want to compare
- two sets of beta bear this in mind
just some quick safety considerations if
you might be involved in mine site
design for example assets the assets are
optically dangerous let me burn you the
risks of fire or explosion with
perchloric acid
you've got fumes and that you have to
deal with you need special extraction
systems with perchloric acid fusions
obviously have the the flux hazards and
heat hazards but generally on mine sites
people prefer fusions because they are
less hazardous and safety is a paramount
concern right let's launch into the for
acid digestion and one of the four acids
we have listed in there perchloric
nitric hf and HCL it's a stage digestion
we don't know we'll throw it into a
beaker and/or test tube and stand back
first of all we add things like nitric
acid to oxidize the sulfides to sulfates
and retain the sulfur it's applicable to
lower level geochemistry and many all's
minimum contaminants and you're doing an
doing the digestion and Teflon so no
dilution you can get your low detection
limits HF dissolves most silicates in
fact almost all of them and what you're
doing is essentially converting your
sample to a soluble perchlorate form of
your sample and you leach that up in
hydrochloric acid and you take it across
your instruments there are some
limitations with for acid digest what
are these principally first of all some
minerals do resist for ester dodges I'm
not saying they will not dissolve but
you cannot guarantee they've all
dissolved in your flaccid dodges I've
listed some of them there and they're
not too many of them those main ones
secondly some elements precipitate at
low dilutions and lead solver sulfates
lead silver chlorides barium sulfate
potassium rubidium as perchlorates
they're kind of one of the exceptions
that the chlorides are generally very
sorry
but potassium rubidium not so much and
some volatile elements are lost and I'm
silicon boron silicon and boron are
Luster's volatile fluorides and there's
some other elements that are lost
partially lost no not not all lost
moving on to three acid artists dozen
three acid you'll note the emission of
HF and that's why they prefer that on
many mine sites because they don't like
working with HF because you don't have
HF a lot of silicates will be partially
dissolved it is generally more
aggressive than a creature and it's
effective against many sulfides oxides
carbonates and particularly a lot of
sulfide ores and that's why it's very
popular in mind science let's move along
to a Korea as Helen mentioned 3 to 1 or
1 to 3 molar mix of nitric and
hydrochloric and forms nitrile chloride
and chlorine and the solution which is
powerful oxidizing complex in reagent
and it dissolves a lot of mineral
species it dissolves precious metals and
nice thing about a creature it's
amenable to up scaling can you big
samples like 25 grams or 10 grams and
you get your gold platinum play at him
coming out in the wash and most of the
gold is dissolved roughly about 95
percent of what you get our fire assay
is dissolved in that Korea but remember
it is not very effective against many
silicates and is not very effective
against refractory oxides things like
rutile ilmenite and it's not selective
that's a mistake people make often get a
lot of people sending in for example
nickel copper nickel magnetic sulphide
ores and they want us to do it by
something like a Korea and they believe
that we all get the sulfide component of
the niccola but not the silicate yeah
and not really it's
it's not selective it will leach
something out of the silicates and most
of the sulfides there are basically of
doing that if you wanted to do that and
there's a very wide range of recovery
for different elements for example
copper generally must have mostly
recovered whereas something like
selenium very poorly recovered I've got
some examples just now living on
something like a solid leach two-tops
we deal with blegh and that's a very low
level analyses great for soil stream
sediments I've seen some marvelous Cal
cricketer cartridge examples with
Blake's and has very very low detection
emits 10 parts per trillion that's good
and there's a big a lot of people are
looking for many Blake's i screen out
the very far infractions and i send it
in for a blegh you don't need a killer
like a normal blake would take you can
do it on 50 grams no problem and very
good numbers coming out of that as well
now moving on for the leach well it's an
accelerated solid leach for gold ores
and what it does is determine determine
the Sun audible gold in the sample and
we can take the tales from the littoral
process and we can dry them reimagine
eyes them Washington rather than
reimagine eyes them and put them through
far si and you can get a very good idea
of what's refractory and what amenable
to a silent process in your oars things
like acid soluble copper and cyanide
soluble copper these are classic partial
empirical techniques the acid soluble
copper uses a sulfuric acid leach and
again remember they no standard
procedures or additives none of them
have things like ferrous sulfate added
in it and they all have different times
temperatures and they will get different
amounts of copper art and we have I
think about twenty of these different
recipes on file at the moment and you
can pick and choose or give us your own
we can do it but most proper
sides of carbonates insoluble and
sulfides are pretty soluble something
like a solid soluble copper which has
very important metallurgical
implications for the fact that it does
use up your cyanide again standard
procedure most proper minerals are
soluble the with the exception of chalk
apart and chrysocolla and then you can
hook them up together as a sequential
digest first of all it dress it soluble
copper and the tails of that process
goes into your solid soluble copper and
then they do a force it on the residue
partial selective Dargis I'm going to go
over this very quickly normally you are
get the a horizon and soils what are we
doing with them we are looking for
buried mineralization ions move through
the substrate the substrate can be
something that's moved in for example
let's write my two movements from
somewhere else till or for example :
sand and barns make their way through
the substrate and they coat the grains
so goes the theory and what we do is
we're not interested in the chemistry of
the substrate we just interested in the
chemistry of of what's actually on the
surface the exogenous label ions and
fine fractions that's a common theme
that we seem to be hearing an awful lot
of late their work best lots of reaction
sites big surface area devoid of barren
phases like quartz and feldspar and
different Dargis work in different
settings some of them are listed over
there
moving on to fusion digests well fusion
digest guarantee total this does
guarantee total dissolution so they're
great for refractory elements for
factory minerals suicide what happens is
you mix the sample of the flux and the
sample dissolves in the flux when you
put in in in the methyl just luck
sugar dissolves in water and then you
dissolve the product of the fusion
process in an acid the disadvantages are
the flux is now you've got all that the
disadvantage of the fusion is now you
got all that flux in the solution and
you also have the crucibles give off a
lot of metals so they will compromise
what they will preclude analysis of
those particular elements they come in a
number of flavors and principally the
lithium borate fusions we analyze them
Platinum where and that ideal for whole
Rock analysis and sulfides are not
particularly kind to to platinum where
although they are tricks of the trade to
limit the damage and then we get the
sodium peroxide fusions which would be
either nickel or zirconium highly
oxidizing and suitable for most all
samples including sulfide ores just
remember you know if you're doing
something like sodium peroxide you now
have sodium in the solution if you do it
in zirconium or have like the zirconium
and hafnium solution so there's a lot of
elements that are excluded by the
process XRF fusions what are we doing an
X or if we're dissolving the sample and
a piece of glass no why would you want
to do such a thing
simply become just before I get on to
that x-ray is a total analysis the XRF
part not the fusion makes it a total
analysis and we get rid of what we call
physical effects particle size and
monological effects so the only
compromise X or if accuracy so if you
get rid of the interactions that x-rays
have with crystals or minerals you get a
far better analysis and your the
corrections you need to make are
relatively simple and can be done or the
computer whereas if you try and encrypt
for powder analyses it's very messy and
they're very difficult and the dates are
not particularly good there's an example
what fusion does look like typical
silicate forty millimeter diameter piece
of glass and there's a is neurons are on
rich sample
Farah say it's a very robust process
which concentrates precious metals
basically gets rid of everything in your
sample that's not precious metals and
you get pretty close to quantitate a
recovery for gold platinum palladium in
the traditional lead collection for
assay and I'm typically use a big sample
which if you want to lower your variance
in your sampling error that is a good
thing
materials like Roma tights and and
copper concentrates for example we're
going to use a smaller sample so you're
not going to do a 50 gram fire assay on
on a copper concentrate unless you do it
five times and put put all the buttons
together the two stages to fara say
firstly the you collect the the precious
metals and a piece of lead and that's
your hold your button and secondly you
get rid of the lead by a process called
cupellation and you put it in a magnesia
Capel and you left behind with the
precious metals what happens is let
oxidizes the Capel magnesia Capel
absorbs the lead oxide and leaves behind
the precious metals and a little bead
called Aprill and you can see that one
didn't work very well with it - Larry a
minute
but yet Farah says are trying to look
for these kind of things it's not an
infinitely robust process but it is very
robust and triple view when things do go
wrong we can pick it up well the
alternative is the nickel sulphide
collection for assay where you can do
gold platinum palladium osmium iridium
rhodium and ruthenium and just some
quick graphs on before we wind up on
different dodges and recovery these are
Orias reference materials and looking at
your child file elements when were
Goldschmidt classification from earlier
and there's some cobble nickel which not
strictly Chaka Falls but basically with
a forest digest and a Curie G reasonably
good recovery on Chaka fall elements not
always for
the lead they might be in might be in
the silicate for example and you would
not recover it real world there Korea
majors and lots of our elements this is
where Korea starts - am i running out of
time one minutes up government okay at
Korea struggles and half yield strength
elements you can see actor age is really
struggling and rare earth elements what
we take away from that is heavy rare
earths are more difficult to extract
than light rails with acid dodges and
your rails patterns might look different
and just to wind up if you doing your QC
lock one should and you can try to enact
to read your process it might look very
good but if you control it on what the
process doesn't do for example a Peter
and what you got off the certificate but
if you're empirical method doesn't do
what's on the such I figured you might
get a whole host of failures that are
not particularly useful but yeah that's
only because you controlling it on the
wrong parameters thank you Richard
[Applause]
5.0 / 5 (0 votes)