Rare metals play an important role in the development of major branches of industry, such as vacuum equipment, semiconductor electronics, nuclear power and rocket production, as well as in the production of special steels and hard, refractory and corrosion-resistant alloys. Rapid development and improvement in the production of rare metals took place in the ten years which have elapsed since the publication of the first edition of this book. These ten years have witnessed the beginning of large-scale production of titanium, zirconium, and germanium, and a significant increase in the production volume; new, improved methods for the separation and purification of metals and compounds (ion-exchange, extraction, crystallization methods) as well as arc and electron-beam melting processes for metals were developed. This made it necessary to rewrite most of this book. In view of the growing importance of the lanthanides and rhenium, chapters on these metals were also included. At the same time, we decided to dispense with the chapters on lead and antimony, since these are not usually listed as rare metals. In describing the metallurgy of each metal, much attention was paid to its physicochemical nature and to the practical operations involved in the main technological processes for the production of its chemical compounds and of the pure metal. This book is a textbook for students specializing in the metallurgy of the rare metals. It is assumed that the student is familiar with the physicochemical fundamentals .of metallurgy, ore dressing, metallurgical furnaces, and processes and apparatus used in extractive metallurgy. The description of standard equipment (leaching apparatus, thickeners, filters, comminution installations, etc.) has accordingly been omitted. The references are grouped together at the end of the book.
