Metallurgy

Metallurgy is the application of scientific knowledge of metals, i.e. how science is used in metal manufacturing, and the construction of metal components used in industrial and commercial applications. Metal working as a craft is not the same as metallurgy. For technological advancement, metal working relies on metallurgy, much as medicine is reliant on medical science. A metallurgist is someone who specialises in the discipline of metallurgy.

History of metallurgy: 

Metallurgy has a long and illustrious history. Metals have been used for nearly 6,500 years, and their current use represents the culmination of that journey. The first known metals were gold, silver, and copper, which were found in their native or metallic state, the earliest of which were most likely nuggets of gold found in the sands and gravels of riverbeds. During the late Stone Age, such native metals became known and valued for their ornamental and useful qualities.

Extraction:

The method of extracting valuable metals from an ore and refining the retrieved raw metals into a purer form is called extractive metallurgy. The ore must be reduced physically, chemically, or electrolytically to convert a metal oxide or sulphide to a purer metal. Feed, concentrate (metal oxide/sulphide), and tailings are the three basic streams that extractive metallurgists are interested in.

After mining, big chunks of ore feed are crushed or ground into minute particles, with each particle containing mostly valuable or mostly waste material. The needed metal can be extracted from waste products by concentrating the valuable particles to allow for separation.

Types of Metallurgy: 

1. Hydrometallurgy: Hydrometallurgy is concerned with extracting metals from ores using aqueous solutions. Leaching is the most prevalent hydrometallurgical process involving dissolving precious metals in an aqueous solution. After the solution is separated from the ore particles, it is often purified and concentrated before the valuable metal is recovered, either metallic or as a chemical compound. Precipitation, distillation, adsorption, and solvent extraction are methods used to purify and concentrate solutions. Precipitation, cementation, or an electrometallurgical process may be used in the ultimate recovery step.
2. Pyrometallurgy: Pyrometallurgy is concerned with high-temperature chemical reactions involving gases, solids, and molten metals. Solids that contain precious metals are either reacted to generate intermediate compounds for further processing or transformed to their elemental or metallic state. Roasting procedures are typical of pyrometallurgical processes that involve gases and solids. Smelting operations refer to a group of processes that result in molten products. The exothermic nature of the chemical reactions, mainly oxidation reactions, may provide all the energy required to sustain high-temperature pyrometallurgical processes. However, energy must often be contributed to the process by fuel-burning or direct electrical energy application in the case of some smelting processes.
3. Electrometallurgy: Electrometallurgy is the study of metallurgical processes in an electrolytic cell. Electrowinning and electro-refining are the two most popular electrometallurgical procedures. Electrowinning is an electrolysis method that recovers metals from an aqueous solution after ore has gone through one or more hydrometallurgical processes. A cathode is made up of the metal of interest, while an anode consists of an inert electrical conductor. An impure metallic anode (usually from a smelting process) is dissolved, and a high purity cathode is produced via electro-refining. Another electrometallurgical method is fused salt electrolysis. The valuable metal is dissolved in molten salt, which serves as the electrolyte, and the valuable metal gathers on the cell’s cathode.

Benefits of Powder Metallurgy:

Compared to other metalworking processes, the powder metallurgy process has some advantages. All of this adds up to better product quality, shape and material flexibility, application variety, and cost-effectiveness due to part-to-part consistency.

Conclusion

Metallurgy was once widely practised as a science. Still, by the mid-nineteenth century, massive metallurgical factories had been created (based on empirical connections, trial-and-error, instinct, etc.) and efficiently functioned. Metallurgy has evolved as a profession and has become more predictive during the last 150 years. As a result, difficulties are frequently posed in the metallurgical sector concerning real issues that plants face while operating, such as low performance, sustainability considerations, etc.