Extractive Metallurgy

Metal is extracted from ores. The main factors which determine whether a particular mineral is an ore of the metal are a)the percentage metal content b)the cost of extraction c) the market price. Broadly, the ore consists of mainly two parts: Metal and Gangue (impurities). The metal is usually reduced from their oxides (ores). The separation of the metal from their impurities is carried out in the extraction the metal. The entire process is known as extractive metall-urgy. The metal can be extracted by different methods. They are classified into the following categories: a) Pyro metlallurgy b) Hydrometallurgy and c) Electrometallurg

Principles of Extractive Metallurgy

Extractive metallurgy as a discipline deals with the ext-raction of metals from naturally occurring and man made resources. Separation is the essence of metal extraction. Development of efficient separation schemes calls for a through understanding of extractive metallurgy principles in terms of physical chemistry (thermodynamics & kine-tics); materials and energy flow/balance, transport phenomena, reactor and reactor engineering, instrumen-tation and process control, and environment and waste management

Mineral Processing and Nonferrous Extractive Metallurgy

The nuclear industry throughout the world is experiencing a dilemma of resource exhaustion, technological innovat-ions, and economic challenges. The energy needs parti-cularly have put enormous pressure on increased consumpt-ion of base and rare metals/rare earths and nuclear metals over the past few decades, calling for devising newer and effective methodologies to utilize available resources/ low grade reserves, besides recycling wastes and by prod-ucts. This has provided a momentum for development of novel techniques in mineral beneficiation/processing, metal extraction, separation, and environmental controls. This also calls for a re-look at the present practices and formulate suitable innovative approaches to cater to tie requirements of energy security of the country

Application of alternative lixiviants for secondary heap leaching of gold

Some preliminary results on the secondary leaching of previously heap leached gold ore are presented. Alternative lixiviants for gold comprising chlorine, thiourea and thiosulphate were compared with cyanide using bottle roll tests. Chlorine was subsequently selected for column leaching tests. Column tests at 1.0, 0.1 and 0.01 gL-1 Cl2 at pH 2 were conducted. The results indicated that about 23 per cent of the gold was leached over 45 days using 1 gL-1 Cl2 at pH 2. The experiments conducted proved that the chlorine/chloride system has good potential for further extraction of gold and silver from the existing cyanide heap leach residues and a process for secondary leaching of gold has been proposed. Further testwork is recommended to extend conditions, sample types, and the duration of leaching period

Vaccum - A New Tool in Extractive Metallurgy

Theoretical considerations involved in metal extraction reactions under vacuum have been discussed.The general advantages of carrying out reactions under vacuum are derived from the lowered temperature for reaction and the possibility of carrying reactions to completion, by the removal of one of the reaction products. The conditions for the reduction and dissociation of oxides, sulphides, halides, hydrides and nitrides are discussed and various examples cited of reactions of this type adopted for metal-winning

Mechanical Activation of Solids in Extractive Metallurgy

Mechanochemistry is the branch of chemistry that has primarily evolved in the twentieth century.It deals with the field of reactions caused by mechanical energy, often referred to as Mechanical or Mechanochemical Activation [1-3]. The process of activation depends on the breakage process and the rate at which energy is supplied to the system [1-3]. In contrast to coarse grinding, where the objective is size reduction, mechanical activation is concerned with structural changes that are brought about by application of mechanical energy. Fine grinding is an intermediate case between coarse grinding and mechanical activation [1-3]. Mechanical activation has been attem-pted in a variety of disciplines, such as extractive meta-llurgy, waste utilisation, mechanical alloying, advanced ceramics, catalysis, coal gasification, paints and dyes, fertilizers, drugs and pharmaceuticals, organometallic synthesis, and many others

Extractive metallurgy Techniques possibly applicable in India

METALLURGY remained an art from the time of Agicola (credited with having written the first treatise on the subject) to the end of the 19th century. In many areas, it remains an art to this day. "This does not mean to imply that no advances have been made in metallurgy. But there are many examples of early metallurgical work which our best scientists today find difficult to explain. An out-standing one is that of the Delhi Pillar at Kutub Minar forged of iron, as far as is known, about the 12th century and still standing, almost unweathered,in uprightposition a few miles outside the city of New Delhi. During the present rocket race, a great deal of scientific work has been done on the metallurgy of steel and special alloys, with the result that ductilities and tensile strengths have increased dramatically within the past twenty years

Mehanokemija i priprema nanokristaliničnih materijala

The possibility of application of mechanochemistry in extractive metallurgy and material science is illustrated. Surface oxidation of mechanically activated sulphides, sorption properties of CaCO3 after mechanical activation, gold leaching from mechanochemically pretreated Cu-Pb-Zn complex concentrate and pilot plant tests of mechanochemical technology (process MELT) have been selected as examples of application of mechanochemistry in physical chemistry and extractive metallurgy. The mechanochemical reduction of Cu2S with the aim to prepare nanocrystalline copper can serve as an example of a novel process for preparation of advanced materials in materials science.U radu su prikazane mogućnosti primjene mehanokemije na procese ekstrakcije u metalurgiji i znanosti o materijalima. Za primjer takve primjene mehanokemije u fizičkoj kemiji i metalurgiji ekstrakcije odabrani su oksidacija površine mehanički aktiviranih sulfida, apsorpciona svojstva CaCO3 nakon mehaničkog aktiviranja, izdvajanje zlata luženjem prethodno mehanokemijski pripremljenog kompleksnog koncentrata Cu-Pb-Zn i pilot-pogonskog testiranja mehanokemijske tehnologije (proces MELT). Mehanokemijska redukcija Cu2S radi pripreme nanokristalnog bakra može u znanosti o materijalima poslužiti kao primjer neuobičajenog procesa za pripremanje poboljšanih materijala