Extractive Metallurgy of Non-Ferrous Metals: Part One


One of the most fundamental yet critical areas of metallurgy relates to the extracting of metals from ores, concentrates, scrap and other sources with a view to refining to the liquid state.
Three methods can be considered as the major processes for carrying our extractive metallurgy activities, pyrometallurgy, hydrometallurgy, and electrometallurgy.

Extractive metallurgy is the art and science of extracting metals from their ores and refining them. The production of metals and alloys from these source materials is still one of the most important and fundamental industries in both developed and developing economies around the world. The outputs and products are essential resources for the metallic, mechanical, electromagnetic, electrical and electronics industries (silicon is treated as a metal for these purposes).

Generally speaking, extractive metallurgy is the process of the extraction of metals from ores, concentrates (enriched ores), scraps, and other sources and their refining to the state of either liquid metal before casting or to solid metals. The extraction and refining operations that are required may be carried out by various metallurgical reaction processes.

Traditionally, methods of extraction and refining have been classified into the following categories:

  • Pyrometallurgy
  • Hydrometallurgy
  • Electrometallurgy

Pyrometallurgical processes (in Greak, ‘pyr’ means ‘more at fire’) are carried out at high temperatures. Hydrometallurgy (in Greak, ‘hydor’ means ‘more at water’) is carried out in aqueous media at or around room tempearture. Electrometallurgy employs electrolysis for separation at room temperature as well as at high temperature.

Another method of classification can be in terms of unit operation or unit process. Pyrometallurgy can be further classified as follows:

1. Solid-state processing: This does not involve any melting. It is typically carried out in the temperature range of 500-1200°C, as exemplified by the roasting of sulphides, calcination, solid-state reduction of metal oxides by H2 and Cao. Solids are mostly immiscible and hence the product of solid state processing is either pure or is a mechanical mixture. In the latter case, it requires further separation.

2. Liquid-state processing: This involves melting of at least the metal-containing phase and is on the whole carried out at a higher temperature. Examples are blast furnace smelting, steelmaking, distillation refining of zinc from impure lead etc. Liquid state processing separates out the metal either in pure or in impure form. Appreciable compositional changes in the liquid are possible due to miscibility, rapid diffusion and mixing.

As mentioned above, a raw ore cannot be used as such as a finished product for industrial or commercial uses.

The steps of the transformation chain, which lead to the production of the final metal, is a technically coherent sequence of processes, which include physical treatments of the ore (grinding and flotation processes).

Figure 1 shows the simplified chain of processes in mineral processing and metallurgical plants:

Figure 1: Process flow chain of non-ferrous extractive metallurgy

Mineral processing

Mineral processing involves the use of physical processes to manipulate ore particle size, and concentrate valuable minerals using the processes of separation, based on such properties of the ore, such as density, chemical composition, electrostatic, magnetic or fluorescence properties. A good example of a separation process is froth flotation.

Also of interest to the mineral processor is the separation of mineral solids from water and aqueous solutions by thickening, filtering and drying.


Pyrometallurgy involves the treatment of ores at high temperature to convert ore minerals to raw metals, or intermediate compounds for further refining. Roasting, smelting and converting are the most common pyrometallurgical processes.

A roasting process is used to extract metals from sulfide ores: in this process the ore is heated in the presence of oxygen and the sulfur is oxidized and driven off as sulfur dioxide. Some metals in this process remain in the sulfide form, while other metals are turned into an oxide form. The desired metal may be in either product.

Oxidative smelting and converting are similar to the roasting process, but differ slightly in the way that the processes' temperatures are high enough to promote melting of materials. Some minerals are more reluctant to oxidation, so they remain in the sulfide form, while other minerals are completely oxidized and form compounds with additives, often called flux. Molten sulfides and oxide compounds split in two layers because of the different specific weights.

The subsequent bi-products of these operations, sulfur dioxide and carbon dioxide, are major pollutants.


Hydrometallurgy involves the use of aqueous solutions to extract metals or compounds from their ores. Some of the hydrometallurgical processes include leaching, precipitation of insoluble compounds, pressure reduction.

Leaching is a process for chemical dissolution of the desired minerals in aqueous solutions. Due to the difference in the dissolution rates, it is possible to separate the compounds of different metals. Often, some oxidative reagents need to be added to promote leaching.

Search Knowledge Base

Enter a phrase to search for:

Search by

Full text


This article belongs to a series of articles. You can click the links below to read more on this topic.

Finding chemical composition data in the Total Materia database couldn’t be easier.

Within seconds it is possible for you to find useful chemical composition data for over 175,000 materials in the database.

Enter the material of interest into the quick search field. You can optionally narrow your search by specifying the country/standard of choice in the designated field and click Search.

solution img

Total Materia will generate the search list for you to select the material of interest from the material list.
Click on the material of interest.

solution img

On the subgroup page, click the composition link to view chemical composition data for the selected material. The number of chemical composition data records is displayed in brackets next to the link.

solution img

The chemical composition data will be then be displayed along with all selected material information for your reference.

solution img

For you’re a chance to take a test drive of the Total Materia database, we invite you to join a community of over 150,000 registered users through the Total Materia Free Demo.