Rhenish brown coals

Correlations Between Petrographical Properties, Chemical Structure, and Technological Behavior of Rhenish Brown Coal... 

The brown coal reserves in the Federal Republic of Germany amount to approx. 56 billion metric tons, 55 billion metric tons of which are in the Rhenish brown coal district located west of Cologne. About 35 billion metric tons of that reserve are considered to be technologically and economically mineable today (1). 

Rhenish brown coal is now mined in five opencast mines with an average depth of about 280 m. Modern mining equipment having a daily capacity of some 240,000 m is used. About 119 million metric tons of brown coal were mined in 1981. 

The petrographical and chemical investigations presented in the following sections were carried out in order to describe the behaviour of the coal types characteristics of the Rhenish brown coal area during refining processes. 

Rhenish brown coal consists of a variety of lithotypes which are already discernible in the coal seam by brightness variations. 

Based on the qualitative assignment of the individual coal components, Rhenish brown coal can be divided into four groups having similar... 

Figure 2. Distribution of the oxygen-containing functional groups in Rhenish brown coal.

Figure 3. Macropetrographical classification of 15 brown coal lithotypes from the Rhenish area. (Reproduced with permission from Ref. 2. Copyright 1981, Schriftleitung Braunkohle.)...

Rhenish brown coal has an average ash content of about 4 % (mf), a volatile matter of about 52 % (maf) and a lower heating value of 25.6 MJ/Kg of coal (maf). The final analysis of the coal under maf conditions shows the following average composition ... 

CORRELATIONS BETWEEN PETROGRAPHICAL STRUCTURE, CHEMICAL COMPOSITION AND REFINING BEHAVIOUR OF RHENISH BROWN COAL... 

There are many investigations and publications available on the briquetting behaviour of brown coals, both from the GDR and the Rhenish area (6 to 9). 

In order to establish statistically usable data on the briquetting behaviour of Rhenish brown coals, the 15 brown coal lithotypes were briquetted under identical conditions (water content, grain size distribution and mould pressure) with a laboratory press. 

These investigations on correlations established between the raw material properties and briquettability of Rhenish brown coal led to the following results ... 

A macro- and micropetrographical analysis with a view to before technological problems involved in the briquetting process allows one at the most to judge the briquettability of Rhenish brown coal on the basis of trend data. 

A correlation analysis of the chemo-physical parameters of Rhenish brown coal and its briquettability gives only trend data as well. Therefore generally an anticipated quality assessment of the briquettes is restricted to the following points ... 

For the purpose of an assessment with a view to refining, the petrographical, chemical and physical properties of lithotypes of Rhenish brown coal were established and compared with one another. 

For the gasification process no usable quantitative relations were established between the petrographical coal properties and the gasification behaviour. It is possible without any material problems to convert nearly all the Rhenish brown coal types into gaseous hydrocarbons or synthesis gas. 

Under the given conditions of the Rhenish brown coal deposit, an opencast mining operation, a high output and the large feed quantities required for future refining plants brown coal petrography is one out of many tesserae for quality assessment. The development of appropriate modes of determining the quality characteristics of raw brown coal is a task indispensable for the future. 

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