The book addresses the issues of chemical and physico-chemical interaction occurring in multicomponent water-salt systems, which are formed at separate stages of the production of complex NP and NPK fertilizers, including gray and magnesium-containing fertilizers. Particular attention is paid to chemical interactions between the individual components, occurring at the stages of granulation and drying, depending on the method and types of input nitrogen, potassium and magnesium-containing components. The book is intended for specialists of industrial enterprises of mineral fertilizers and design organizations, researchers, graduate students and students engaged in the field of chemical technology of inorganic substances.