Tiêu Chuẩn Iso 00622-2016.Pdf

© ISO 2016 Solid mineral fuels — Determination of phosphorus content — Reduced molybdophosphate photometric method Combustibles minéraux solides — Dosage du phosphore — Méthode photométrique au molybd[.]

Solid mineral fuels — Determination

Comb stible s minéra x solide s — Dosage du p osph r — Méth de

p otométrique a moly do h sph te réduit

S con edition

2 16-1 -1

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F r eword i v

1 Sc ope 1

2 Nor mati ve r eferenc es 1

3 Terms an definitions 1

4 Principle 1

4.1 Ex tr action 1

4.2 Dete mination 1

5 Re g ents 2

6 A pparatus 2

7 S mple preparatio 3

8 Proc ed re .3

8.1 Dry ox idation method 3

8.2 Wet ox idation method 4

8.3 Dete mination 5

9 Ex pres io of r esults 5

9.1 Method of calculation an formulae

5 10 Precision of the method 6

1 1 Repeatabi ty 6

1 2 Reprod cibi ty

6

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ISO cola orat es closely with the Int ernational Ele trot ech ical C mmis ion (IEC) on al matt ers of

ele trot ech ical s an ardization

The proc d r s used t o develo this document an those int en ed for it furthe maint enanc ar

desc ibed in the ISO/IEC Dir ctives, Part 1 In p rticular the dife ent a pro al c it eria ne ded for the

dife ent ty es of ISO document should be not ed This document was draft ed in ac ordanc with the

edit orial rules of the ISO/IEC Dir ctives, Part 2 ( e www.iso.org dir ctives)

A tt ention is drawn t o the p s ibi ity that some of the element of this document ma be the subje t of

p t ent right ISO shal not be held r sponsible for identifying any or al such p t ent right Detai s of

any p t ent right identif ied d ring the develo ment of the document wi be in the Introduction an / r

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Te h ical Bar ie s to Trade (TBT) se the folowing URL: www.iso.org iso/for word.html

The committ ee r sponsible for this document is ISO/TC 2 , S ld mine als f el s , Subcommitt ee SC 5,

Meth ds o a alys i s

This se on edition canc ls an r plac s the firs edition (ISO 6 2:1 8 ), w hich has be n t ech icaly

r vised Thisdocument incorporat eschang es r lat ed t o r fe enc s an othe minor it ems folowing it

sy st ematic r view

Solid mineral fuels — Deter mination ofphosphor us c ontent

This document spe if iesa r d c d moly do hosphat e phot ometric method for the det ermination of the

t otal phosphorus cont ent of hard co l, lgnit es an coke Two methods for taking the phosphorus int o

solution ar spe ified, namely extraction from theco l or coke ash with acid or b r peat ed o idation of

the co l or coke, b acid, t o r move carb nac ous matt er

2 Normati ve referenc es

The folowing document ar r fe r d t o in the t ext in such a wa that some or al of their cont ent

cons itut es r q ir ment of this document F or dat ed r fe enc s, only the edition cit ed a pl es F or

un at ed r fe enc s, the lat es edition of the r fe enc d document ( inclu ing any amendment ) a ples

ISO 3 3, L b ratory glas swar — Inte cha gea le c onic al gro nd joint

ISO 5 5, Tes t s ieves — Metal w ir cloth, pe frated metal plate a d elec troormed she t — Nomin l s i zes

o o enin s

ISO 1 7 , S ld mine al f els — Dete min tio o ash

ISO 1 2 3, Hard c oal a d c oke — Ma u l s ampln

3 Terms and definitions

No t erms an def initions ar def ined in this document

ISO an IEC maintain t erminolo ical data ases for use in s andardization at the folowing ad r s es:

— IECEle tro edia: a aia le at ht p:/ www.ele tro edia.org

— ISO Onlne brow sing plat orm:a ai a le at ht p:/ www.iso.org o p

4 Principle

4.1 Ex traction

Method 1: R emo al of carb nac ous mat erial b ashing in a muf le furnac un e spe ified con itions,

an extraction of phosphorus b tr atment with hydrofluoric an sulph ric acids

Method 2: R emo al of carb nac ous mat erial b r peat ed o idation with nitric acid in the pr senc of

sulph ric acid

A ddition of ammonium moly dat e an ascorbic acid solution t o the acid solution Measur ment of the

a sorb nc of the r sulting blue solution b a suita le o tical ins rument

5 Reag ents

During the analy sis, use only r ag ent of r co niz d analytical grade an only dis i ed wat er or wat er

of eq iv lent purity

5.1 Hy rofluor ic acid, a pr ox imately 40 g /l solution

WARNING — A queo s hy rofluoric acid is a highly cor osive lquid w hich at acks glas ; the

v apo r is ir itant and toxic Its actio o the skin and eyes is strongly cor osive, producing

severe and painful burns w hich may not be immediately evident and w hich respo d slow ly to

tre tment The solution sho ld be handled o ly inside a wel-venti ated fume cupboard In the

event of co tact or suspected co tact, flo d with water and se k immediate medical attentio

The manufacturer’s l terature sho ld be co sulted for furthe informatio

5.2 Sulphuric acid, a pr ox imately 49 g /l solution

5.3 Sulphuric acid, conc ntrated, ρ 1,84 g /ml, a pr oximately 9 % (m/m) solution

5.4 Nitric acid, conc ntrated, ρ 1,42 g /ml, a pr ox imately 7 % (m/m) solution

5.5 A mmo ium mol ybdate, 6 g /l solution

5.6 A sc or bic acid, 5 g /l solution

Pr p r the solution fr sh dai y

5.7 A ntimony p tas ium tar tr ate (KSbO·C

4 H

4 O

6 ), 1,3 g /l solution

5.8 Re g ent solutio

Mix 2 ml of the sulph ric acid solution (5.2), 1 ml of the ammonium moly dat e solution (5.5), 1 ml

of the ascorbic acid solution (5.6) an 5 ml of the antimony potas ium tartrat e solution (5.7) Pr p r

fr sh immediat ely befor use

5.9 Phosph r us, s an ar d s ock solution corresp n ing to 0,1 0 g of P pe ltr e

Weigh, t o the near s 0,0 0 1 g, 0,43 2 g of p tas ium dihydrog en mono hosphat e (KH

2 PO

4 ) (dried

at 1 0 °C for 1 h) an dis olve in wat er Trans e the solution q antitatively t o a 1 0 0 ml one-mark

v lumetric flask, diut e t o the mark an mix

1 ml of this s an ard st ock solution contains 0,1 0 mg of P

5.10 Phosph r us, s an ar d wor king solution corresponding to 1 mg of P pe ltr e

Trans e 1 ml of the s andard phosphorus solution (5 9) t o a 1 0 0 ml one-mark volumetric flask, diut e

t o the mark an mix Pr p r fr sh immediat ely befor use

1 ml of this s an ard working solution contains 1 μg of P

6 A pparatus

Ordinary la orat ory a p ratus an

6.1 Mufle furnac e, as spe ified in ISO 1 7

6.2 Dish, of si ica, p r celain or platinum, asspe ified in ISO 1 71

6.3 Insulating plate, of si ca, 6 mm thick, or its eq iv lent ,of such siz as to be an easy slding fit into

the mufle furnac (6.1)

6.4 Platinum c ucible, of ca acity 2 ml to 3 ml, with ld

6.5 Hot-air bath

6.6 Dig estio ap aratus ( e Fig ur e 1), cons ructed of b r osi cate glas , consisting of the folowing :

6.6.1 Flask, K jeldahl flask, of ca acity 3 0 ml, fited with a 24/ 9 g r oun g las socket complying with

ISO 3 3

6.6.2 F me duct, of out ide diamete a pr oximately 28 mm, fited with a dr op ing fun el of ca acity

at leas 1 ml and a 24/ 9 g r ou d glas cone complying with ISO 3 3 The fume d ct ma y beof one pie e

or as embled from sp te u its b means of g r ou d glas joint

6.6.3 F me e x tractor, comprising a glas tube of diamete a pr oximately 40 mm, sealed at one en

and drawn out at the othe en to form a con e tion to the wate pump The tube is fit ed with a drain

s o cock and a se ies of lp ed holes to ac ommodate a n mbe of fume d ct

6.7 Spectr ophotometer, or p otoelectr ic absor ptiometer, of the r eq ir ed sensitivity

The sample of co l or coke shal be the analy sis sample, groun t o p s a 2 2 μm t es sieve complying

with the r q ir ment of ISO 5 5, taken an pr par d in ac ordanc with ISO 1 2 3 The sample shal

be thoroughly mix ed, pr fe a ly b a me hanical means, immediat ely befor the det ermination

8.1 Dry ox idation method

8.1.1 Dete mine the per centag e of ash in the co l or coke as spe ified in ISO 1 7 Grind the ash in an

agate mortar to p s a 6 μm sieve complying with ISO 5 5

8.1.2 Weigh, to an ac ur acy of 0,1 mg , a out 0,0 g of the ash into the platin m c ucible(6.4)

8.1.3 Add 2,0ml of the sulph ric acid solution (5.2) an a out 2,0ml of the hydr ofluoric acid solution

(5.1) Plac the ld on the c ucible an dig es on a b i ng wate b th for 3 min in a wel-ventiated

fume cup o r d Remo e an rinse the ld, cole ting the washing s in the c ucible A llow the solution to

ev p rate on the wate b th u til mos of the hydrofluoric acid an wate ha ve be n r emo ed

8.1.4 Transe the c ucible to the hot-air b th (6.5), ev porate until dense white fumes fr om the

sulph ric acid ha ve ev lved for a few minutes A llow to co l, add 0,5 ml of the sulph ric acid solution

(5.2), heat or a few min tes an alow to co l

NOTE It is es ential that he contents of the c ucible are not evaporated completely to dry es at an sta e

8.1.5 Add a out 2 ml of wate to the c ucible and dig es on the wate b th for 3 min, when al the

ex tract should be in one solution A llow to co l, trans e the solution to a 1 0 ml one-mar k v lumetric

flask an diute with wate to the mar k ( olution A )

If the sample has a high arsenic cont ent, this can int erfe e with the r sult an the solution should be

r d c d befor the phosphorusdet ermination

8.1.6 Pr ep r e a blan solution exactly as desc ibed a o e, but omiting the co l or coke ash

8.2 Wet ox idation method

8.2.1 Weigh, to an ac uracy of 1 mg , a out 1 g of the co l or coke sample

8.2.2 Tr anse the tes p rtion (8.2.1) to the clean, dry K jeldahl flask (6.6.1) A ssemble the a p ratus

(6.6) as shown in Fig ur e 1, in a wel-ventiated fume cupb ar d Add 7 ml of the sulph ric acid (5.3) an

3,5 ml of the nitric acid (5.4) b means of the dr op ing fu nel, rotating the flask so as to wash down any

sample r emaining in the ne k

8.2.3 A fte the initial r eaction has subsided, heat the flask car efuly so that the r eaction proc eds

smo thly and without frothing C ntin e heating the flask u de the same con itions u ti only fumes of

sulph ric acid ar e ev lved Add 0,2 ml to 0,4 ml of the nitric acid (5.4)to the dr op ing fu nel an ru the

acid, drop b drop, into the flask

NOTE If violent rothing oc ur on ad ition of the mix ed acid, ap ly a damp cloth t o the neck of the flask an

he t intermit ently as the frothing subsides

8.2.4 Heat for 2 min to 3 min u ti no mor e dense brown fumes ar e ev lved Repeat the ad ition of

the nitric acid an the heating , r otating the flask pe iodicaly to wash down any car bonac ous mate

ad e ing to the sides of the flask, u ti al visible car bonac ous mate has be n ox idiz d and the solution

is a p le g r eenish-yelowish colour This ma y take 1 1 2 h to 2 h, or even long er in exc ptional cases with

some coke samples

NOTE For the f ir t 1 min of he ting a co l sample, the re ction mixture is a tar y mas ; subseq ently, it

chang s its colour from black t o dark red ish-brown, to amb r, an f inal y t o a pale gre nish-yelow If a black

liq id stil remains aft er 45 min he ting, either

a) to low a t emperature has b en used an the nitric acid has not re cted with the sample; raise the

temperature to distil of ex ces nitric acid, then contin e the normal o idation as des rib d, or

b) to high a temperature has b en used, nitric acid b ing distil ed of without re cting; co l, ad more nitric

acid an he t he mixture as des rib d

8.2.5 Heat the flask mor e s r ongly u ti white fumes a pear an alow to fume for 5 min C ol the flask

to a prox imately room temperatur e, r emo e the dr op ing fu nel an fumed ct as embly an ad a few

glas beads to the content of the flask

NOTE If the colour reverts to amb r or de p red, ad a further 0,2 ml t o 0,4 ml of the nitric acid, he t t o

fuming an alow to fume for 5min

8.2.6 Add cautiously 1 ml of wate , heat u til white fumes a pear an then alow to fume g ently for

1 min C ol the flask u ti the ev lution of the white fumes c ases, ad 0,2 ml of the nitric acid, r eheat

the flask an alow to fume for a furthe 1 min

8.2.7 To ensur e complete ox idation, co l the flask to a pr ox imately r oom temperatur e an r epeat the

pr oc d r e desc ibed in 8.2.5

8.2.8 C ol the flask to a pr ox imately r oom temperatur e, ad 1 ml of wate , heat to fuming an alow

to fume for 2 min A dd a furthe 1 ml of wate , heat o fuming , alow to fume for 1 min an co l

8.2.9 Add a furthe 2 ml of wate to the flask an dig es on the b i ng wate b th for 3 min, when al

the ex tract should be in solution Fite the solution thr ough a hardened, acid-washed fite p pe , alow

to co l, tr ans e the fitrate to a 1 0 ml one-mar k v lumetric flask an diute w ith wate to the mar k

( olution B) ( e the note in 8.1.5)

8.2.10 Pr ep re a blan solution exactly as desc ibed a o e, but omitting the co l or coke sample

8.3.1 Pipete 1 ml ofsolution A or B asa pr opriate ( e 8.1.5or 8.2.9)( he alq ot p rtion taken ma y

be v ried ac or ding to the phosphorus content of the sample), 1 ml of the blan solution ( e 8.1.6 or

8.2.1 as a propriate) an 1 ml of the s an ar d solution (5.10) into separate 5 ml one-mar k v lumetric

flasks A fourth 5 ml flask isr eq ired for the r eag ent blan

Calbration is lnear for alq ot p rtions containing up t o 3 μg of phosphorus W ith high phosphorus

co ls or cokes, it ma be ne es ary t o takea smal e al q ot portion

8.3.2 Pipete 5 ml of the r eag ent solution (5.8) into each flask, swir ling the contents d ring the

ad ition, di ute with wate to the mar k, and mix thor oughly A llow to s and for 20 min

8.3.3 Measur the a sorbanc e of the solutions a ains wate, in the spe tro hotomete (6.7) using 40 mm

c ls at a wavelength of 7 0 nm or in the photoele tr ic a sor ptiomete fited with an a pro r iate fite

9 Ex pres ion of r esults

9.1 Method of calculation and formulae

Calculat e the pe c ntag e of phosphorus (P) in the analy sis sample, using F rmulae (1)an (2)

a) Dry o idation method ( e 8.1):

Vm D D

10 0

−

−

(1)

w he e

A is thepe c ntag e of ash in the analy sis sample;

m is themas , in grams, of ash taken;

V is thev lume, in mi l itr s, ofsample solution taken for colour develo ment ;

D

1

is thea sorb nc of the sample solution;

D

2

is thea sorb nc of the sample blan solution;

D

3

is thea sorb nc of the s an ard phosphorus solution (5.1 );

D

4

is thea sorb nc of the r ag ent blank solution

b) Wet o idation method ( e 8.2):

Vm D D

1

−

−

(2)

w he e

m is the mas , in grams, of the t es p rtion;

V, D

1

, D

2

, D

3

an D

4

ha e the same meaning as in a) a o e

R ep rt he r sult, pr fe a ly the mean of d plcat e det erminations, t o the near s 0,00 %

10 Precision ofthe method

10.1 Repe tabi ity

The r sult of d plcat e det erminations, car ied out at dife ent times in the same la orat ory b the

same o e at or with the same a p ratus on two r pr sentative p rtions taken from the same sample

( e Clause 7), should not dife b mor than the v lues given in Ta le 1

10.2 Reproducibi ity

The means of the r sult of d plcat e det erminations, car ied out in two dife ent la orat ories on

r pr sentative p rtions taken from the same sample ( e Clause 7), should not dife b mor than the

v alues given Ta le 1

Table 1

Ph sp orus cont ent of

co l or coke

% (m/m )

R epeata i ity R eprod cibi ity

Les than 0,0

E ual t o or more than 0,0

0,0 2 a solute

1 % of the me n of

the results

0,0 5 a solute

2 % of the me n of

the results

Key

1 to p mp

Figure 1 — Ap aratus for wet o idatio of the sample