On the Role of Chemical Interaction Between the Humic Component of Peat Mass and Iron Oxides in the Production of Fuel-Smelting Materials
Abstract Generated abstract
This paper examines whether chemical interaction between the humic component of peat and iron oxides contributes to the strengthening of peat-based fuel-smelting materials containing finely dispersed iron ore. Using electrokinetic potential measurements, group chemical analysis, and infrared spectral comparison of peat and peat-ore mixtures, the authors assess possible formation of dissociable iron compounds and changes in peat components. The results indicate some evidence of iron ion involvement and a modest increase in uronic acids in bitumens, but no substantial spectral changes in readily hydrolyzable compounds or humic acids. The study concludes that briquette strengthening is mainly due to physicochemical and mechanical structure-forming processes, while chemical interaction plays only a minor role.
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ON THE ROLE OF CHEMICAL INTERACTION BETWEEN THE HUMIC PART OF PEAT MASS AND IRON OXIDES IN THE PROCESS OF PRODUCING FUEL–SMELTING MATERIALS
S. I. Smolyaninov, G. T. Krinitsyn, A. I. Senchenko
(Presented by the scientific-methodological seminar of KhTF)
In addressing the question of obtaining raw material for the blast-furnace process on the basis of peat, it was found that introducing finely dispersed iron ore into an intensively dispersed peat mass in an amount of 6–10% relative to raw peat \((w = 85\%)\) leads to strengthening of the resulting material in comparison with peat molding without additions of iron ore.
The reason for this phenomenon must above all be determined by a change in the colloidal properties of the raw peat mass when iron oxides are introduced, which, in all probability, affects the course of structure-forming processes both in the initial system and in the process of drying the molded material [1].
However, of considerable interest may be the question of the presence of chemical interaction between the mineral components and the reactive components of the group composition of peat. Processes of this kind will influence not only the physical and physicochemical properties of the air-dry product, but also the course of reactions of thermal decomposition of the organic mass of peat and reduction of iron oxides.
The appearance of new formations can be recorded by methods of X-ray structural analysis. The investigation was carried out on a URS-50 X-ray unit by the Debye–Scherrer method. To confirm the occurrence of chemical reactions, it is sufficient to show that mobile iron ions appear in the system, the iron previously having been present in the form of oxides.
The presence of ions in a colloidal system leads to compression of the diffusion layer and to a decrease in the electrokinetic potential [2]. In this connection, an attempt was made to prove the possibility of the transition of iron, when its oxides are mixed with peat, from the oxide form into compounds capable of dissociation in solution with the formation of an ion.
For the investigation, Tagan peat of transitional type was taken, with a degree of decomposition of 20%, an initial moisture content of 85%, and an ash content of 9.6%. From the peat, samples were prepared with additions of 0.5% by weight of ferric chloride and 3% of iron protoxide–sesquioxide.
Then peat samples without additions and with additions were subjected to complete moisture saturation, after which the electrokinetic potential of each system was measured. Measurements were carried out by the electroosmosis method in powder diaphragms [3]. The measurements began after the electrical conductivity of the saturating medium ceased to change. The values of the electrokinetic potential obtained for peat, peat-
peat with the addition of ferric chloride and a mixture of peat with iron oxide–hydroxide gave, respectively, results of 3.66 mV, 1.88 mV, and 3.31 mV.
In view of the fact that structural changes do not affect the electrokinetic potential, and the addition of iron oxides was insignificant, it was concluded that the change in the value of the electrokinetic potential is due to the formation, in the mass, of dissociated iron compounds and to the incorporation of iron ions into the colloidal particles.
The interaction of peat mass with oxides should lead to certain changes in the chemical composition of the peat, which can be detected by analyzing its group components. To verify this assumption, a group analysis was carried out on peat and on peat with the addition of 10% iron oxide–hydroxide. In the course of the analysis, bitumens, water-soluble
Fig. 1. a) Infrared spectrum of readily hydrolyzable compounds of peat.
b) Infrared spectrum of readily hydrolyzable compounds of a peat–ore mixture.
c) Infrared spectrum of humic acids of peat.
Fig. 2. Infrared spectrum of humic acids extracted from a peat–ore mixture.
soluble compounds and humic acids. The peat bitumens were analyzed; in the course of the analysis the content of waxes, resins, asphaltenes, paraffins, and uronic acids was determined. The most substantial changes were observed in the content of uronic acids. In the bitumens from peat with an admixture of iron oxides, their amount is 4.5% higher than in peat without additives.
The infrared spectra of the readily hydrolyzable compounds and humic acids of the peat and of the peat-ore mixture did not reveal substantial differences in the chemical composition of these components (Figs. 1, 2).
Conclusion
It should be recognized that the strengthening of the peat briquette upon the introduction into it of finely dispersed inclusions of iron oxides occurs as a result of physicochemical-mechanical processes. The role of chemical interaction is insignificant.
References
- I. V. Gebler, S. I. Smolyaninov, A. P. Neznanov. Izv. TPI, vol. 112, 1963.
- S. S. Voyutskii. Course of Colloid Chemistry. “Khimiya,” 1964.
- O. N. Grigorov et al. Practical Manual for Laboratory Work in Colloid Chemistry. “Khimiya,” Moscow, 1964.