Proceedings of the Tomsk Order of the Red Banner of Labor Polytechnic Institute named after S. M. Kirov

Vol. 126　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　1964

Effect of Additions of Iron Ore and Fluxes on the Yield of Peat Semi-Coking Products

K. K. STRAMKOVSKAYA, V. D. IVANOVA

(Presented by Professor, Doctor I. V. Gebler)

An analysis of the literature on the pyrolysis of solid fuel shows that, among the numerous factors affecting the process of peat semi-coking, the influence of mineral additives on the yield of pyrolysis products is the least studied, and their influence on the composition of the tar is even less studied. Investigations carried out [1] with Baltic shales, which are high-ash fuels and whose mineral portion contains limestone and clay as the main components, gave contradictory results. Pure calcium carbonate, limestone, sand, and other substances were used as additives. At the same time, the authors gave differing explanations for the decrease or increase in tar yield. A. Kyll [1] used shale ash as an additive in an amount 2–3 times that of the shale. The shale with the additive was subjected to semi-coking at a temperature of 480°. As a result, the tar yield decreased, the gas yield also decreased, while the yield of semi-coke increased; this was explained by the adsorptive properties of the ash, which contained free calcium oxide and therefore primarily absorbed the acidic components of the tar and gas. In the tar, the acid content decreased from 24.9 to 8% and below. S. M. Bruk [2] showed that the addition of 5% freshly reduced iron during the pyrolysis of gas coals increased gas evolution by 6%, the yield of crude benzene by 42, and the yield of coke by 7%, while the tar yield decreased by 4.7%. With the addition of iron oxides, some increase in the yield of all coking products was observed, which is quite improbable.

A. N. Khidosheli and M. B. Ravich [3, 4] showed that the introduction of NaOH and Na₂CO₃ into the fuel promotes deeper cracking of the liquid and gaseous products of coal semi-coking. The consequence of this is a decrease in the yield of primary tar, an increase in the yield of gas and gas benzine, and also an increase in the yields of low-boiling fractions during distillation of the primary tar.

At present, in connection with the study of the question of using fuel-and-smelting materials in metallurgy—materials consisting of briquettes or moldings made from fine ores and fuel, or from fuel, ore, and fluxes—there has arisen a need for a detailed investigation of the influence of the mineral portion on the yield and composition of semi-coking tars during the pyrolysis of these materials. Of particular interest is the study of

study of the effect of additions of ore and fluxes on the yield and composition of products in the semi-coking of peat in connection with the development of the problem of using fuel-smelting materials based on peat in the gas-blast-furnace process.

In this process, along with the smelting of pig iron, it is envisaged to obtain gas and tar as raw materials for organic synthesis.

In the present work the effect of additions of ore and fluxes on the yields of semi-coking products was investigated.

Fuel-smelting materials (FSM) were prepared on the basis of Tagan peat, the composition of which is given in Table 1.

Table 1

Composition of peat

Ore from the Bakchar deposit was used, and limestone was used as the flux. The composition of these materials is given in Tables 2 and 3.

Table 2

Composition of the ore

Table 3

Composition of fluxes

Composition of the fuel-smelting materials: peat ($W_p$ 20%) — 59%, iron ore — 35%, limestone — 6%.

The results of semi-coking in a standard retort at a temperature of 500° are given in Table 4.

The calculated absolute experimental error with respect to the yield of tar from peat is 0.034, and the relative error is 0.17%. These same values in experiments with fuel-smelting materials are, respectively, 0.16 and 1.00%. Whereas the average absolute yield of tar from peat is 19.55, and from fuel-smelting materials 15.89, the average absolute difference between these values is 3.66%, i.e., it considerably exceeds the absolute experimental errors and indicates a certain decrease in tar yield during semi-coking of fuel-smelting materials.

For gas, the absolute values of deviations in experiments with peat are 0.23, and with FSM — 0.32, whereas the average increase in gas yield from FSM is 0.67. The yield of semi-coke varies within the limits of error.

experiment. The decrease in tar yield during the semi-coking of TPM, with a simultaneous increase in gas yield, indicates the cracking action of the iron-ore and flux additions during peat semi-coking.

Table 4

Yield of semi-coking products

Conclusions

It has been established that the addition of iron ore and fluxes to peat in the preparation of fuel-smelting materials during semi-coking produces a cracking effect, which leads to a decrease in tar yield and an increase in gas yield.

References

1. A. Ya. Aria. On the influence of mineral matter during the thermal decomposition of kukersite oil shale. Proceedings of TPI, No. 48, 1953.

2. A. S. Bruk, Z. A. Volkova et al. On the catalytic action of various substances during the pyrolysis of complex organic substances (coals). Eighth Mendeleev Congress on General and Applied Chemistry. Section of Chemistry and Chemical Technology of Fuels, Publishing House of the Academy of Sciences of the USSR, 1959.

3. A. Khidasheli. Investigation of the influence of catalysts on the yield of primary tar during the dry distillation of peat. Proceedings of the Georgian Polytechnic Institute, No. 5, 81–84, 1957.

4. M. B. Ravich. Investigation of the influence of additions of sodium compounds on the process of semi-coking of coals. ZhPKh, vol. XXIV, No. 9, 970–975, 1951.