Ruhr Coal Basin

the principal coal basin of Western Europe. Located in the Federal Republic of Germany, in the Land (state) of North Rhine-Westphalia, primarily on the right bank of the lower Rhine and in the basin of its tributaries—the Ruhr, Emscher, and Lippe rivers—and partly on the left bank. The Ruhr Coal Basin has an area of 4,500 sq km and measures 140 km from east to west. In 1972 its total geological reserves were 213.6 billion tons. The deepest mines (1970) are the Hugo (940 m) and the Katharina (900 m).

The coals of the Ruhr Coal Basin are limited to Carboniferous deposits, specifically to Upper Carboniferous strata—sandstones, shales, and coal and limestone seams with a total thickness of 5,000–6,000 m. These strata have been formed into large anticlines and synclines, which have an amplitude of up to 2,000 m. Broken by transverse faults and powerful thrust faults, the lower strata (Lower Namurian) have no coal, but the upper strata (Westphalian stage) are productive. The Carboniferous deposits are unconformably overlain by less disturbed Permian, Triassic, and Cretaceous deposits measuring more than 1,000 m thick.

In the productive strata there are as many as 200 coal seams more than 0.5 m thick, including 48–60 seams with a working thickness of more than 1 m. The coals have a medium and low ash content (6–8 percent) and a low sulfur and phosphorus content. Many of the coals (60–65 percent) are long-flame coals, which produce good coke and have a combustion heat of 36–36.5 megajoules/kg (8,600–8,700 kilocalories/kg); 10–12 percent are short-flame coals.

Mining conditions in the Ruhr Coal Basin are very complex. They include heavy tectonic dislocation, extensive flooding, and a rapid increase in temperature with depth. Annual coal output in the Ruhr Coal Basin declined from 102 million tons in 1963 to 90 million tons in 1970 and 78.1 million tons in 1974.