Extractive metallurgy includes a branch known as pyrometallurgy, which enables the recovery of many valuable metals through the use of thermal treatments. These thermal treatments spur chemical and/or physical transformation and are responsible for many of the alloys, compounds and pure metals we see and use today.
Extractive metallurgy includes a branch known as pyrometallurgy, which enables the recovery of many valuable metals through the use of thermal treatments. These thermal treatments spur chemical and/or physical transformation and are responsible for many of the alloys, compounds and pure metals we see and use today.
The Processes of Pyrometallurgy
In order to achieve a pure metal, alloy or intermediate compound, a mineral must typically firstpass through one or more of the processes associated with pyrometallurgy. These processesinclude drying, roasting, calcining, smelting and refining. Each process requires some form ofenergy input in order for the process to successfully occur and complete.
The Calcining Process
Calcining is a process that causes a material to decompose through the use of heat. This process is carried out through the use of fluidized bed reactors, shaft furnaces and rotary kilns. In this process, hydrates decompose, as do many carbonates, oxides and dioxides.
The Drying Process
The drying process removes moisture from materials using thermal methods. The most frequently used aspect of drying is combustion gases. These gases are hot and are typically generated when fossil fuels are burned. However, other methods to achieve the drying process are hot air and indirectly heated inert gas. In most cases, the temperature will be set at 120 degrees Celsius or higher, depending upon the temperature required to initiate vaporization of the moisture.
The drying process is achieved through the use of flash dryers, rotary dryers and fluidized bed dryers. However, spray drying can also be involved in this process. This occurs through the use of an aqueous solution, which completely dissolves a material, and then the material is placed in an evaporation chamber where the solids will crystallize.
The Roasting Process
Gas-solid reactions that occur thermally are involved in the roasting process. The reactions mayinclude reduction, sulfation, pyrohydrolysis, chlorination and oxidation. Metal sulfides are one ofthe most frequently oxidized ores that the roasting process is used for. In roasting, the solidproduct is known as the calcine.
Dead roasting occurs when gas and temperature conditions cause complete oxidation. Partialroasting occurs when the oxygen used is not sufficient for the feed to fully oxidize. Sulfationroasting occurs when gas and temperature conditions cause sulfides to react and produce metalsulfates versus metal oxides.
The Smelting Process
When thermal reactions include at least one molten phase product, the process is consideredsmelting. This is frequently used for metal oxides, which can be heated with charcoal or coke toresult in a more refined mineral. Other ores, such as carbonates can also be smelted usingcharcoal as a reduction agent; however, other materials might be required to aid in the process.
Smelting typically occurs at temperatures above the metal’s melting point, which can varygreatly depending upon the ore.
The Refining Process
Removing impurities thermally from materials is known as refining. A wide variety of differenttypes of processes can be involved within the refining process, as well as several different typesof furnaces. The electrolytic process can also be involved in refining.
To find out more about superalloys and general mining topics, please visit PublicMining.org, a free resource directory showcasing public mining companies like Crescent Resources, Cream Minerals and thousands more.
Leaching: The Many Processes Behind the Mining and Crushing of Ore
Leaching is the process of extracting metal from the ore for refinement. Leaching is also referred to as the metallurgical process. It is also simply called metallurgy.
Mineralogy: History, Methods and More
The study of minerals and their structure, chemistry and physical properties is known as mineralogy. Mineralogy also encompasses several other processes, which include classification,distribution worldwide, formation, origin and utilization.
Superalloys: Chemistry, Process Development, Uses and Costs
Superalloys are also referred to as high performance alloys. To be identified as a superalloy it must exhibit great mechanical strength, have good surface stability, have creep resistance when under high temperatures, and resist both oxidation and corrosion. The base of a superalloy is typically cobalt, nickel, or nickel iron.
