Stefan Jasieńko

The behaviour of sulphur forms during pyrolysis of low-rank coal

Abstract Flame coal was pyrolysed up to 1700°C in a fixed bed in an atmosphere of the evolved gases. Sequential changes in the sulphur form distribution were quantitatively determined. A marked enrichment in organic sulphur was observed between 330 and 600°C when conversion of pyrite into ferrous sulphide occurred. SEM with X-ray microanalysis showed that the reduction of pyrite followed the changes in its morphology, from massive to dendritic structure. Above 1000°C, ferrous sulphide began to lose sulphur. The organically combined sulphur appeared to be stable at 1700°C. A sulphur removal of 89.8% was achieved at this temperature. The effects of the reaction of the coal matrix with the sulphur from pyrite decomposition and the presence of alkali minerals in the original coal on the efficiency of its desulphurization during pyrolysis were also considered.

Properties and structure of different rank anthracites

The properties and structure of anthracitic coals through to meta-anthracites were examined using a variety of analytical methods. With increasing rank, the following increased as well: moisture content, carbon content, vitrinite reflectance, reflectance anisotropy, microhardness, real and apparent density, whereas volatile matter content, hydrogen content and calorific value decreased. Increasing rank effected an increase of the spatial ordering of organic matter of the anthracites, decrease of the interlayer distance, and increase in the crystallite dimensions. Also, the number of condensed aromatic rings in the basic structural unit of the anthracites, index of condensation and aromatisation and total surface area and pore volume increased. The differences in the properties and structures of the anthracitic coals and meta-anthracites are described.

The nature of coking coals

Abstract A review of the properties and the structure of coals occupying the middle position in the coalification scale that show the best coking properties — gas coals, gas-coking coals, ortho, meta and semi-coking coals — with particular regard to their behaviour on heat treatment is presented. Problems of coking coals as components of blends in the production of metallurgical coke, as component and binding agent in the process of obtaining metallurgical formed-cokes, and the utilization of coking coals and their extracts as raw materials in the electrode industry, are discussed. The classification of coking coals and questions still to be solved concerning the origin, properties, structure and rational utilization of coking coals, are commented on.

Solvolysis of three Polish coal samples by treatment with N-methyl-2-pyrrolidinone and an NaOHCH3OH mixture☆

Abstract This study concerns the extractable materials obtained by solvolysis of three Polish coals. N-methyl-2-pyrrolidinone extraction and NaOH CH 3 OH treatment of these coals were compared using several analytical procedures (extrography, sonication, gas capillary column chromatography, and i.r. and 1H n.m.r. spectroscopy). Thermodesorption, on line with gas chromatography and mass spectrometry, was also applied to these coal samples.

Biodegradation of hard coal and its organic extract by selected microorganisms

Abstract Biotransformation of powdered hard coal and its organic extract was achieved by means of Piptoporus betulinus, Nocardia rubra and Pseudomonas aureofaciens in aqueous medium. The process of depolymerization was evaluated on the basis of Chromatographic and spectral data. Gas chromatograms, high-performance size exclusion chromatograms and u.v., i.r. and 1 H n.m.r. spectra are discussed.

Sulfur characterization of Polish coals, their lithotypes and macerals

Three coals of different rank (Ro = 0.58–1.01%), and the lithotypes and macerals separated from these coals, were analysed in this study. The wet chemical technique was used to determine the distribution of sulfate, pyritic and organic sulfur forms in the coals and lithotypes. The morphology, size and mode of occurrence of pyrite were examined by optical microscopy and scanning electron microscopy with energy dispersive X-ray (SEM-EDX) analysis. An oxidative technique was developed to study the organically bound sulfur in the maceral microsamples. Pyritic and organic sulfur accounted for nearly all the sulfur in the coals examined and their lithotypes. In comparison with the coals, the lithotypes had a higher proportion of very fine pyrite. Pyrite was most abundant in fusain. The organic sulfur content in the lithotypes decreased in the order: clarain > vitrain > durain > fusain. An analysis of the SO2 evolution profile from temperature programmed oxidation (TPO) of the maceral concentrates indicated that exinite showed the most distinct changes in the chemical structure of sulfur compounds with coal rank. Based on the TPO study a new parameter describing the reactivity of organic sulfur of macerals is proposed.

The behaviour of petrographic constituents of hard coals in coking process and structure of the cokes obtained

Abstract The behaviour in the coking process of the main petrographic constituents - vitrinites, exinites, micrinites and fusinites - separated from hard coals of different rank (from flame coal to anthracite), and the differences in structure of the obtained cokes were examined and discussed.

Co-carbonization of hard coals and coal extracts 1. The co-carbonization of low rank coals with extracts

Studies on the influence of an additive derived from coal on the coking properties of lower-rank coals and on the structure of cokes obtained from blends have been undertaken in our laboratory since 1978. The two coal extracts from flame coal (Int. Class. 900) and gas-coking coal (Int. Class. 632) were used as additives. The results indicate that the blends prepared from low-rank coals — flame coal (Int. Class. 900), gas-flame coal (Int. Class. 721) and the extracts possess better coking properties in comparison to the parent coals. The optical texture and the degree of structure ordering of the cokes obtained from blends is related to the amount of extract in the blend. With increasing extract content in the blend, increases were observed in the amount of optically anisotropic areas in cokes from low-rank coal/extract blends and the crystallite height (Lc) of cokes from the blends. The isotropic optical texture of cokes from low-rank coals can be modified by coal extracts to an anisotropic optical texture. The non-fusible coal is the most difficult to modify. An explanation of the observed phenomena is given.

Sulfur groups in the cokes obtained from coals of different ranks

Abstract Coals of different ranks having their sulfur content distributed in different forms were heated up to 1000°C. It was shown that the higher the rank of the coal the more sulfur remained in the coke. The retention of sulfur in the coke is strongly dependent on the proportion of the thiophenic sulfur in the organic coal sulfur. The sulfur in the cokes examined was mainly organic in form. Iron sulfide, FeS, constituted most of the inorganic sulfur. A correlation was observed between the sulfide sulfur content in coke and the pyritic sulfur content in coal. The form and size of the iron sulfide present in the coke were determined by microscopic examination.

Co-carbonization of hard coals and coal extracts 2. The co-carbonization of medium- and high-rank coals with extracts

Abstract Studies on the influence of anthracene coal extracts on the carbonization process of medium- and high-rank coals were undertaken. Extracts from flame coal (Int. Class. 900) and gas-coking coal (Int. Class. 632) were used as additives. The blends prepared from the examined coals and the extracts exhibited better coking properties than the parent coals. The addition of extract to the coals gave an increase in the microstrength of the resultant cokes. The effects of co-carbonization of coking coals with extracts were increases in the size of the optical texture as well as in the degree of structural ordering of cokes. In the co-carbonization of semicoking coal with addition of coal extracts, a reduction in the size of the anisotropic units and a decrease in the crystallite height of cokes were observed. No modification of the basic anisotropy of coke from anthracite by coal extract was observed. With increasing extract content in anthracite/extract blends there was an increase in the degree of structural ordering of co-carbonization products. Extract addition was unable to modify the behaviour of fusinite. Based on the results of investigation of the influence of coal extracts on the carbonization of different-rank coals, a division of coals according to the modification of the optical texture of coke is given.