Abstract |
This report cites results of an experimental study on the distribution of rare-earth and nonferrous metals in coal combustion in grate-fired (flame grate-fired) furnaces. Many rare, scattered and nonferrous metals (gallium, molybdenum, tungsten, scandium, niobium, tantalum, lead and others) have been discovered in solid energy fuel (coals and shales). Currently, hundreds of millions of tons of energy fuel are mined which could become a serious potential raw material source of rare-earth and nonferrous metals even if their concentration in coal and shale is not high. The bulk of energy coals and shales are used as fuel for power plants; moreover, their mineral components are divided between slag, which is separated out in the furnace chamber of water heaters, and the so-called ash soot, which is carried out of the furnace chamber by gaseous combustion products and to a certain degree is recoverable by the devices of the sanitation purification of flue gases. According to theoretical calculations, the elements listed above are distributed in different ways between the slag and ash soot. As a result of these reasons, solid combustion products can be extremely enriched by a certain valuable component to a percentage where the ash soot can be considered a raw material for industrial extraction of this component. In particular, it has been established that minute fractions of ash soot are enriched with elements which form sublimating compounds. |