Study of the Tar from Semicoking of Peat Fuel-Smelting Materials
Abstract Generated abstract
This study characterizes tar produced during semicoking of peat fuel-smelting materials composed of Tagan peat and iron-ore concentrate, with the aim of assessing its potential technological use. The authors determine physicochemical properties, group and fractional composition, and the characteristics of phenolic and neutral oil fractions, comparing key features with tar from semicoking of peat alone. The tar is broadly similar to peat semicoking tar, but shows a higher light fraction yield, lower phenol content, increased pitch, and evidence of greater pyrolysis. Distillation to 330°C yielded 66% distillate containing 83% of the tar phenols, and gas-liquid chromatography of the light neutral oils identified small resources of benzene, toluene, xylenes, and ethylbenzene.
Full Text
STUDY OF THE TAR FROM SEMICOKING OF PEAT FUEL-SMELTING MATERIALS
K. K. Stramkovskaya, L. A. Ponomareva, L. F. Glukhova
(Presented by the scientific-methodological seminar of the Chemical-Technological Faculty)
The use of peat fuel-smelting materials, consisting of iron ore and peat, in a chemical-metallurgical process will make it possible to obtain, along with metal and gas, a considerable quantity of low-temperature, slightly pyrolyzed tar. To develop a rational technology for using this tar, a detailed study of it was carried out. The tar was obtained in a specially designed installation [1] from fuel-smelting materials (TPM) prepared from Tagan peat and iron-ore concentrate, added in an amount of 17% relative to air-dry peat. The physicochemical characteristics, fractional composition, and characteristics of individual fractions obtained by distillation of the tar are presented in Tables 1–5.
Table 1
Physicochemical characteristics of the tar
| Indicators | Semicoking tar of TPM |
|---|---|
| Density | 0.999 |
| Molecular weight | 229 |
| Solidification temperature | 21.6 |
| Contents, % of anhydrous tar: | |
| insoluble in benzene | 6.7 |
| phenols | 14.1 |
| bases | 2.1 |
| carboxylic acids | 1.1 |
| paraffins | 5.9 |
| waxes | 6.8 |
| asphaltenes | 2.7 |
| neutral oils (by difference) | 60.6 |
Analysis of these data and comparison with those for tar from semicoking of peat without ore additions show that, in terms of physical constants and the principal indices of group composition, the tars obtained under identical conditions from pure peat and from fuel-smelting materials containing iron ore differ hardly at all; however, a more detailed study of various tar samples indicates some differences between them. Thus, in fractional composition the tar from semicoking of fuel-smelting materials is distinguished by a somewhat higher yield of the light fraction boiling up to 200°C, a considerably lower yield of the 200–230 and 230–270°C fractions, and also by an increased amount of pitch. The two-hundred-degree fraction
the tar from semicoking of TFM has a lower molecular weight and density. A characteristic feature of semicoking tar from fuel-smelting materials is the smaller amount of phenols: 14.1 as against 15.7%. The relative content of light phenols that passed into the fractions boiling up to 230°C, as the data in Table 2 show, is greater in it by 6.2%; the semicoking tar of TFM is more pyrolyzed than the semicoking tar of pure peat.
Table 2
Characteristics of the distillate fractions
| Indicators | up to 200 | 200—230 | 230—270 | 273—300 | 300—330 |
|---|---|---|---|---|---|
| Density | 0.9145 | 0,9502 | 0,9703 | 0,9819 | 0,9947 |
| Molecular weight | 103 | 140 | 184 | 175 | 200 |
| Viscosity in cSt at 20°C | 1,10 | 11,65 | 12,85 | 15,89 | solidifies |
| Content, % | |||||
| Phenols | 14,8 | 24,8 | 27,9 | 8,9 | 4,8 |
| Acids | 2,6 | 3,8 | 2,1 | 1,4 | 1,1 |
| Bases | 3,2 | 4,8 | 2,8 | 2,5 | 1,8 |
| Solid paraffins | — | — | — | 9,8 | 32,6 |
| Neutral oils by difference | 79,4 | 67,2 | 67,2 | 77,6 | 39,7 |
| Elemental composition, % C | 79,75 | 77,54 | 75,42 | 80,40 | 81,34 |
| Elemental composition, % H | 9,64 | 9,15 | 8,84 | 10,70 | 9,85 |
| Elemental composition, % O | 10,61 | 13,31 | 15,74 | 9,19 | 8,81 |
Table 3
Distribution of phenols by fractions
| Indicators | Semicoking tar of peat | Semicoking tar of fuel-smelting materials |
|---|---|---|
| Passes, as % of all tar phenols, into fractions: | ||
| up to 200 | 15,7 | 20,5 |
| 200—230 | 16,6 | 18,2 |
| 230—270 | 48,6 | 42,3 |
| 270—300 | 10,6 | 4,6 |
| 300—330 | 3,7 | 5,7 |
| Total passed into fractions | 95,3 | 93,3 |
| Remained in the pitch | 4,8 | 6,7 |
From Table 4, which characterizes the phenols isolated from each fraction separately, it is evident that the bulk of them should nevertheless be assigned to the high-boiling ones.
In the neutral oils (Table 5), attention is drawn to the small content of unsaturated compounds in the fractions boiling above 230°C, and the fairly considerable content in the light fraction. The bromine number of the neutral oils of the light fraction is 24 g per 100 ml.
The neutral oils of the first fraction were distilled in a rectification column with an efficiency of 25 theoretical plates into fractions boiling up to 82, 82–109, 109–115, 115–137, and 137–150°C. The component composition of the fractions obtained, determined by gas–liquid chromatography, made it possible to judge, with some approximation, the resources of benzene hydrocarbons in the neutral oil of the tar fraction boiling up to 200°C. In this oil there were determined: 0.28% benzene,
Table 4
Characteristics of phenols isolated from distillate fractions
| Indicators | up to 200°C | 200–230 | 230–270 |
|---|---|---|---|
| Yield of phenols per fraction, % | 14.8 | 24.8 | 27.9 |
| Density \(d_{4}^{20}\) | 0.9147 | 0.9805 | 0.9981 |
| Molecular weight | 126 | 129 | 137 |
| Elemental composition: | |||
| C | — | 77.06 | 75.95 |
| H | — | 8.17 | 8.82 |
| O | — | 14.77 | 15.25 |
| Fractional composition: | |||
| Initial boiling point, °C | 120 | 169 | 178 |
| 10% distilled up to temperature, °C | 183 | 189 | 205 |
| 20% —"— | 186 | 204 | 221 |
| 30% —"— | 193 | 218 | 229 |
| 40% —"— | 208 | 234 | 242 |
| 50% —"— | 218 | 248 | 258 |
| 60% —"— | 236 | 256 | 276 |
| 70% —"— | 271 | — | 284 |
| 80% —"— | 286 | — | 291 |
| 90% —"— | 292 | — | 320 |
| 92% —"— | 305 | — | 328 |
4.17% toluene, 2.10% m- and p-xylenes, 0.68% o-xylene, and 0.82% ethylbenzene, which, recalculated to the original tar, amounts respectively to 0.05, 0.74, 0.37, 0.14, and 0.15%.
Conclusions
-
A detailed characterization is given of the tar from semicoking of fuel-smelting materials and of the fractions obtained from it.
-
It is shown that the yield of distillate fractions with an end boiling point up to 330°C is 66%, into which 83% of all the phenols of the tar pass.
-
Analyses were carried out of the phenols isolated from the fractions.
-
By gas–liquid chromatography, the resources of light aromatic hydrocarbons in the neutral oils of the tar from semicoking of fuel-smelting materials were shown.
Table 5
Characteristics of neutral oils of distillate fractions of the tar from semicoking of fuel-smelting materials
| Indicators | up to 200 | 200–230 | 230–270 | 270–300 | 300–330 |
|---|---|---|---|---|---|
| Yield of neutral oil per fraction, % | 63,7 | 54,6 | 68,4 | 70,8 | 76,5 |
| Yield of neutral oil per tar, % | 11,3 | 5,4 | 12,9 | 5,8 | 8,6 |
| Molecular weight | 138 | 167 | 183 | 208 | 219 |
| Viscosity, cSt | 2,05 | 4,54 | 7,75 | 8,32 | 12,86 |
| Bromine number, g of iodine per 100 g of oil | 24,4 | — | 8,5 | — | 5,1 |
| Percentage sulfonated | 77,5 | — | 80,0 | — | — |
| Fractional composition: initial boiling point, °C | 112 | — | 195 | 221 | 238 |
| 10% distilled up to temperature, °C | 132 | — | 232 | 235 | 246 |
| 20% —"— | 146 | — | 241 | 249 | 288 |
| 30% —"— | 163 | — | 252 | 258 | 299 |
| 40% —"— | 175 | — | 275 | 289 | 346 |
| 50% —"— | 191 | — | 284 | 296 | 352 |
| 60% —"— | 208 | — | 290 | 302 | 360 |
| 70% —"— | 229 | — | 298 | 311 | — |
| 80% —"— | 248 | — | 306 | 320 | — |
| 90% —"— | 281 | — | 313 | 356 | — |
| 94% —"— | 286 | — | 327 | 360 | — |
REFERENCES
- K. K. Stramkovskaya, L. F. Karpova. Study of phenols of tar from the thermal decomposition of peat. Izvestiya TPI, vol. 146, 1967.