ISSN 1068�364X, Coke and Chemistry, 2014, Vol. 57, No. 2, pp. 41–42. © Allerton Press, Inc., 2014.Original Russian Text © E.A. Koshelev, V.K. Fritsler, A.S. Chernyshov, 2014, published in Koks i Khimiya, 2014, No. 2, pp. 17–19.

41

Various means are adopted to predict coke qualityand optimize coal utilization. The basic characteristicsof the coal are determined by technical analysis andpetrographic study, along with the clinkering and otherproperties. The ever�more�stringent requirements onmetallurgical coke entail determination of the ashcomposition, which greatly affects its reactivity CRIand hot strength CSR.

With allowance for all the processes involved(intake, coal storage, batch preparation, coke produc�tion), only a few days pass between coal delivery to theenclosed store and the charging of the batch in thecoke oven, whereas determination of the ash composi�tion takes 3–4 days. That prevents ongoing monitor�ing of the coal quality and timely correction of thebatch composition on that basis. To accelerate thedetermination of the ash composition, OAO Koks hasacquired a Spectroscan MAX�GV spectrometer,which permits swift and precise determination of thesulfur and phosphorus content in coal and the ashcomposition.

The following are some benefits of the SpectroscanMAX�GV spectrometer:

—replacement of the expensive and energy�inten�sive SRM�18, 25, and 35 quantometers;

—listing in the Russian state register of instru�ments and certificate of verification;

—completely automatic analysis;—minimum requirements on the operators;—certification by the Russian Ministry of Health,

which eliminates the need for radiation monitoringand registration with the State EpidemiologicalInspectorate;

—fast analysis (10–100 s per measurement,depending on the element and its content);

—analysis in the range from sodium Na (atomicnumber 11) to uranium U (atomic number 92);

—simple maintenance (only a 220�V single�phasevoltage; absence of water and gas).

—low power consumption (200�W X�ray tube);—more precise analysis, since, in contrast to the

quantometers, the background may be taken intoaccount, which is very important for trace elements.

Thus, the Spectroscan MAX�GV spectrometer ispreferable to the quantometers and to importedinstruments in the express analysis of coal, ash, varioussolutions, hard deposits, steel, alloys, ferroalloys,electrolytes, galvanic baths, slags, slurries, sinters, andconcentrates.

Its applications include the following:—in industry, to determine the elementary com�

position of various products and to control technolog�ical processes;

—in ferrous and nonferrous metallurgy, to monitoralloy compositions;

—in mining and enrichment, to control the keyprocesses;

—in geology and geochemistry, to identify mineraldeposits;

—in ecology, to determine the heavy�metal con�tent in the atmosphere, water, soil, etc.

As already noted, the Spectroscan MAX�GV spec�trometer is used at OAO Koks to determine the sulfurand phosphorus content in coal and the ash composi�tion.

The regression method is used in determining thesulfur and phosphorus content in coal. This methodemploys calibration characteristics—that is, empiri�cal formulas obtained by the analysis of measurement

Determining the Ash Composition of Coal by X�Ray Spectrometry

E. A. Koshelev, V. K. Fritsler, and A. S. ChernyshovOAO Koks, Kemerovo, Russia

e�mail: eak@kem.metholding.ruReceived December 23, 2013

Abstract—For timely determination of the ash composition in coal, chemical analysis has been replaced byX�ray analysis using a Spectroscan MAX�GV spectrometer at OAO Koks. That permits prompt determina�tion of the ash basicity, which affects the reactivity and hot strength of the coke. The plant’s coal purchasesare optimized to stabilize and improve the coke’s CSR and CRI values.

Keywords: X�ray spectrometer, ash composition, reactivity of coke, hot strength of coke

DOI: 10.3103/S1068364X14020112

COAL

42

COKE AND CHEMISTRY Vol. 57 No. 2 2014

KOSHELEV et al.

results for samples of known composition (calibrationsamples). For this purpose, the plant laboratory selectscoal samples with different sulfur and phosphoruscontent.

Switching from chemical determination of the sul�fur and phosphorus content to a spectroscopic methodpermits analysis of the whole range of coals and con�centrates supplied to OAO Koks, since the analysis issignificantly faster. For example, chemical analysis ofthe sulfur and phosphorus content takes 40 min and9 h, respectively, as against 5 min for spectrometricanalysis of both elements. The sulfur and phosphoruscontent in the available coal is taken into account inbatch formulation.

On the Spectroscan MAX�GV spectrometer, theash composition is determined by the fundamental�parameter method, using standard samples. The exci�tation of X�ray fluorescence in the coal sample isdescribed by means of theoretical formulas, and thenthe radiation is recorded by the spectrometer, with cal�culation of the concentration of a particular elementor oxide in the sample. The state standard sample ofcoal ash is used as the standard.

Most of the elements present in coal are deter�mined on the spectrometer: silicon, aluminum, iron,magnesium, calcium, sodium, potassium, sulfur,phosphorus, manganese, and titanium. Their effect onthe coal and coke quality will be different. For exam�ple, high sulfur and phosphorus content weakens andbreaks down the coke structure; 1% increase in theSO3 content reduces CSR by 20–24% (rel.) andincreases CRI by about the same amount.

Note that CRI is a key characteristic of the coke,influencing the blast�furnace process. In particular, itaffects the temperature distribution and gas fluxes inthe furnace and hence the utilization of the gas and thedegree of composition of the reducing agent. In addi�tion, CRI affects the strength of the coke mass in the

furnace hearth, since gasification weakens the struc�ture of the coke [1].

Most elements exist in a state of interdependence.This is expressed by the basicity index, which is theratio of the content of alkaline oxides (oxides of iron,calcium, magnesium, sodium, and potassium) andacidic oxides (silicon and aluminum oxides) [2]

To obtain coke with CSR < 60%, we require batchwith Ib < 2.5. Thus, Ib offers an additional way ofassessing coal quality. For example, on the basis of Ib,we may reject some coal that is satisfactory in terms oftechnical analysis, petrographic characteristics, andclinkering properties but not in terms of ash composi�tion (high content of calcium, iron, and sulfur oxides).By rejecting such coal and optimizing the batch interms of ash composition, CRI was reduced by 5.9%from 2011 to 2013 (from 39.9 to 34.0%), while CSRwas increased by 11% (from 41.7 to 52.7%).

The Spectroscan MAX�GV spectrometer greatlyhastens and simplifies the analysis and permits moni�toring of all the coal and concentrates supplied to OAOKoks. It permits stabilization and improvement of thecoke’s CSR and CRI values, optimizing the batchcomposition.

REFERENCES

1. Bulanov, E.A., Zainutdinov, V.N., Kuznetsov, V.Ya.,et al., Predicting the hot strength CSR and reactivityCRI of coke, Koks Khim., 2005, no. 5, pp. 23–26.

2. Miroshnichenko, D.V., Preliminary assessment of theCRI and CSR values of coke on the basis of the physicalproperties of coal ash, Coal Chem., 2008, vol. 51, no. 11,pp. 447–451.

Translated by Bernard Gilbert

IbFe2O3 CaO MgO Na2O K2O+ + + +( )Ad

SiO2 Al2O3+( ) 100 V daf–( )������������������������������������������������������������������������������������ 100.×=