The analysis of inorganic siliceous materials by atomic absorption spectrophotometry and the hydrofluoric acid decomposition technique

SHORT

445

COMMUNICATIONS

The analysis of inorganic siliceous materials by atomic absorption spgctrolphotometryandt)le~ydrofIuoricaciddecompositiontechnique Part IV. The analysis of cements, clinkers, raw mixes and siliceous Iimestones In the cement and related industries rapid and reliable methods are required for production control, particularly of the constituents silicon, aluminium, iron and calcium. Atomic absorption spectrophotometric methods have been described1 for the determination of various components of cement. However, some of these schemes do not describe a method for silicon, and in other schemes the determination of silicon is lengthy and tedious. In the present scheme, hydrofluoric acid is used to obtain silicon in solution. Methods are described for the determination of silicon, aluminium, iron and calcium in cements, clinkers and raw mixes, particularly of the Portland type; the scheme is also applicable to the analysis of siliceous limestones. In the sample solution it is possible to determine other constituents, e.g. magnesium, sodium, potassium, titanium, manganese and chromium. Before analysis, samples of raw mix and siliceous limestone must be ignited, e.g. in a high-frequency induction furnace, to convert them to an acid-decomposable state. Reagtvzts a92d soEutio92s

The reagents required for the present determinations are listed in Part 12; the detailed preparation of the primary standard solutions (designated below as metal standard I) is also described in Part I. The composition of the secondary standard solutions is given below. Each of these series is prepared for measurement of a definite dilution of the sample solution ; this is indicated in each case. Szlico~t (undihted sample sohtions). Transfer by plastic pipette 8-12 ml, in steps of 0.5 ml, of silicon standard I to plastic bottles, add 20 ml of calcium reagent solution (31.5 mg CaO/ml) and water to a final volume of IOO ml. (Range: 16-24~/~ SiOa, in steps of I%.) Alurrtilziunt (u?2dilzrted sample soZ~22tio?ts). Transfer up to 40 ml, in steps of 2 ml, of aluminium standard I to roe-ml volumetric flasks, add 20 ml of calcium reagent solution and dilute to volume with water. (Range: up to 8% AlsOa, in steps of 0.4%.) Iron (undiluted sample solutions). Transfer up to 50 ml, in steps of I ml, of iron standard I to xooo-ml volumetric flasks and dilute to the mark with water. (Range: up to 5 o/oFez03, in steps of o.I.O/~.) Calciwn (sample solutions diluted zoo tinzes). Dilute calcium standard I to a concentration of 0.02 mg GO/ml with water. Transfer 30-34 ml, in steps of I ml, of this solution to roe-ml volumetric flasks, add I ml of nitric acid and 20 ml of lanthanum reagent solution (50 mg La/ml) and dilute to volume with water. (Range : 60-68% CaO, in steps of 2 %.) Procedure Weigh 1.0000 g of cement, clinker, ignited a plastic beaker. Moisten the sample with water, of hydrochloric acid (I + I). Place the beaker on the sample has decomposed. Add 3.0 fo.2 ml of

raw mix or limestone, and transfer to cover the beaker and add 40 f 2 ml the boiling water bath and heat until hydrofluoric acid, heat on the boiling Anal. Chim. A&a, 44 (IgGg) 445-446

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446

water bstlz for 5-G min, add 20 ml of saturated boric acid solution and continue the the cooled solution to a x000-ml locating until a clear solution is obtained. Transfer volumetric flask and dilute to volume with water. Deterr.~ine silicon, aluminium and iron in the main solution. Determine calcium 135’pipetting 10 ml of the main solution into a xoo-ml volumetric flask, dilute to volume wit11 water. Transfer x0 ml of this solution into another Ioo-ml volumetric flask, add 1 ml of nitric acid, 20 nil of lanthanum rea,qnt sol.ution and dilute to volume with water. Deterlninc silicon and aluminium wit11 the acctylcnc-nitrous oxide flame, and iron and calcium with the acctylenc-air flames. Make tllc mcasurcments and calculntions as clcscrihed iii Part I”.

No.

The methods were tested 13~ analyzing the U.S. Burcnu of Standarcls sample data arc given in Table I. (Portlancl cement) and 2 clinkers. The analytical

1013

si

.‘I f

as Si 02

0s

ClL

I:l’

,‘I I20:,

as

I:c~o:,

(1.~

P-x,) (‘X, ) -...-.___-.__._.. ^._ ..__... -- . .._ ~._ ._ (‘X, ) .-..-.-- ----.-. -._._.--._._-__.-. IJ.S.13.S. IOI .l

Clinker L’

Clinltcr I I

19.53;

x.-19.51

C,..1.3; ~-O..p

lo*@:

1\== I<).‘19

(,.sb; h-b.38

19.53 lQ.05; s=: 1g.52 19.39: s = 0.12 1g.fe ; c = o.Gr

5.5” 5.55; 5.60;

S”5.57 S =0.03

Jj,s;t;

c -0.g.t

10.39

5.60

2 I ..}3 2r .z.+; .g=no.ga 20.81; s = 0.42 20.58; C = 2.0

d.50 4.37; S==.#G 4.45; s =0.06 .}..tfJ; C = I.3

ZO.SG

4.53

____l________ L’s = arithnwtic \‘ZLlUL’.

_ ...__.__ _,_. ___

IlIc;LII VillUC: S =

I

----..-

2.55 : ,y== 2._ql 2.57; h=2.p

CD3.27; S:==63.13 A = fij . 10 02.gS;

2.86 2.85; 2.86: 2.YG; 2.82

G.} . ‘17

3.24

Oq.34; G.}.r‘j; 04.21; 6.t. 24

~:=:2.Sc, s -0.02 C ==o.(ig

3.26;

x=3.25

3.23;

S =O.OI

3.26; 3.26

C ==0.31

65.55 65.G.t; G5.58; Gg.14; 65.05

x=6.+.28 s = 0.13 C 0.20

X=65,3g s = 0.28 C = 0.<+3

.._. _~__.____...__._____.__-_.__-__ .-----C = rcl:Lti\vc deviation ; A = ccrtificntc

stxnclarcl clcviation;

The authors gratefully acknowleclgc for Scientific and Industrial Research. Cltentical Imtitute A, Ustiversity of OsZo, BZi~tdew

CnO

P%II) ..__. -_..-..--

grants

from the Royal

Norwegian

F.

Council

J. LANGMYHR

1’. E. PAUS

(Norway)

SCC ~~6,: 1X. I?. CROW, W. G. I-ImE AND J. n. CONNOLLY, .J. .PCA Xcs. Develop. Lnb., 9 (1967) 60: L. CAPACI-IO-DELCADO ANU D. C. &TANNING, ~f~~ly~l, 5)2 (1g67) 553; T. TAKIuJC~~I AND RI. SUZUKI, TdcWltCL, II (I&.) 1391.

2 F. J.LANG~IYHRAND

(Received A,wZ. Cfht.

P.E.

September Ada,

I"AUS,il.)tnl.Ct~~)rr.RCtn,

gth, 1968)

44 (rg6g) 445-446

43 (1068) 397.