Mangan i cementdamm
Sammanfattning: Manganese is a heavy metal that acts an essential micronutrient for plants and animals, as well as it is toxic in great amounts. Mn2+ is the form of manganese that is biologically available for plants and micro organisms living in soil. How much manganese a plant needs and tolerates varies greatly among different species. The amount of available manganese in soil also varies among different soil types, depending on the origin of the minerals in the soil. The available amount of manganese also depends on the plant it self, as different species affect their environment in different ways. The research that has been made on the effects of cement plants on the environment shows similar results. The content of manganese in the air, in dust deposition and in soil is slightly higher around a cement plant. In most cases it’s not obvious that this is due to the cement production, as it is difficult to separate which contamination is due to the actual cement production and what is coming from other activities around the plant such as transports. There are also studies carried out in the same purpose that does not analyze the effects of manganese but of other metals. There is no research available on Swedish cement plants and nothing that specializes in manganese. In literature describing the process of cement manufacturing manganese is considered a non volatile compound that will be incorporated in the burnt clinker. Today the use of renewable fuel and raw material is increasing to lower carbon dioxide emissions and replace the fossil fuel used by the mineral industries. Limestone used as raw material contains significantly more manganese then the renewable fuel. Limestone contains manganese as manganese oxides which are not volatile in the cement manufacturing process, which means that no great emissions will occur. A very small amount of heavy metals will always evaporate but will be caught in the electro filters in the chimney. A certain amount of dust will also be emitted, how much varies greatly and depends on the type of process used. Emissions from industries and activities are regulated by Swedish law and the European Union. Manganese is often grouped together with other metals, for example Sb, As, Pb, Cr, Co, Cu, Ni and V, and the emission of the total amount of all these metals including manganese is limited. This can pose a problem for the development and use of renewable fuel and raw material for the mineral industries as manganese is present in sedimentary rocks in greater amounts then the other metals it is often grouped with.
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