Progress in our knowledge of thermodynamics and physico-chemical factors in manganese ferroalloy production has developed rapidly during the past twenty-five years or so. The authors' intention has been to use this basic knowledge in discussions of industrial manganese ferroalloy production. The book presents the principles and current knowledge of processes in the production of high carbon ferromanganese, silicomanganese and low carbon manganese alloys. The book is intended for professionals working in production, plant design or development. It will also be useful for researchers in industry, universities and research institutes. The book can be used as a textbook for courses in extractive and process metallurgy, and for company in-house courses. Thermodynamics of the slag and metal systems are extensively covered. Computational modelling based on assessed thermochemical databases has made it possible to calculate and present a large number of phase and equilibrium diagrams. These diagrams are useful for easy understanding and analysis of the complex heterogeneous equilibria in the manganese ferroalloy metallurgy. The manganese ferroalloys are mainly produced in electric submerged arc furnaces. Electrical relations are briefly discussed. Supply of raw materials, especially manganese ores and coke, is extremely important for the manganese industry. The book gives the reader appropriate knowledge regarding the selection the best of available raw materials. Environmental issues, including greenhouse gas emissions and climate changes, are of growing concern to ferroalloy producers. Carbon will always be needed as a reducing agent, and consequently emission of CO2 gas is inevitable. The book describes solutions to dealing with pollution problems and gives the latest guidelines for greenhouse gas inventories.