Ferroalloys

METALS & MINERALS

Ferroalloys

We produce and market chrome ore, ferrochrome and vanadium, and we are one of the world’s largest and lowest-cost producers. We also market manganese ore and alloys.

Ferroalloys in figures - 2020

kt of ferrochrome produced from our own sources
0
mlb of vanadium pentoxide produced from our own sources
0

Uses of ferroalloys

Ferrochrome

Most of the world’s ferrochrome is used in the production of corrosion resistant steel, more specifically stainless steel.

Manganese alloys

Most of the world’s manganese is used in carbon steel production.

Ferrovanadium

Vanadium alloys are used to strengthen specialty steels for use in niche and high-end applications. It is also used in the production of vanadium redox batteries.

Here in our Analytical Services laboratory here, we have great experience working with ferroalloys. But what exactly are they and what are they used for?

Ferroalloys – an overview

Ferroalloys is a term used to identify various alloys of iron with a high proportion of one or more other elements; e.g. Cr, Al, Mn, Mo, etc. Used in the production of different steels and alloys and closely associated with the iron and steel industries, ferroalloys are produced generally by two methods: in a blast furnace or in an electric arc furnace:

a)    A BLAST FURNACE produces liquid metals by the reaction of a flow of air (oxygen) introduced under pressure into the bottom of the furnace with a mixture of metallic ore, coke (reducing agent), and flux (generally limestone) fed into the top. Coke is ignited at the bottom and burned rapidly with the forced air. The iron oxides in the ore are chemically reduced to molten iron by carbon and carbon monoxide from the coke. The slag formed consists of the limestone flux, ash from the coke, and substances formed by the reaction of impurities in the ore with the flux; it floats in a molten state on the top of the molten iron. Hot gases rise from the combustion zone, heating fresh material in the stack and then passing out through ducts near the top of the furnace. The raw materials require 6 to 8 hours to descend to the bottom of the furnace where they become the final product of liquid slag and liquid iron. Modern furnaces are highly efficient, to pre-heat the blast air and employ recovery systems to extract the heat from the hot gases exiting the furnace.

b)    An ELECTRIC ARC FURNACE consists of a refractory-lined vessel, usually water-cooled in larger sizes, covered with a retractable roof, and through which one or more graphite electrodes enter the furnace. The furnace is primarily split into three sections:

  1. the shell, which consists of the sidewalls and lower steel “bowl”;

  2. the hearth, which consists of the refractory that lines the lower bowl;

  3. the roof, which may be refractory-lined or water-cooled, and can be shaped as a section of a sphere, or as a frustum (conical section). The roof also supports the refractory delta in its centre, through which one or more graphite electrodes enter.

A typical alternating current furnace is powered by a three-phase electrical supply and therefore has three electrodes. The arc forms between the charged material and the electrode, the charge is heated both by current passing through the charge and by the radiant energy evolved by the arc. The electric arc temperature reaches around 3000C. The regulating system maintains approximately constant current and power input during the melting of the charge, even though scrap may move under the electrodes as it melts.

AC furnaces usually exhibit a pattern of hot and cold-spots around the hearth perimeter, with the cold-spots located between the electrodes. Modern furnaces mount oxygen-fuel burners in the sidewall and use them to provide chemical energy to the cold-spots, making the heating of the steel more uniform. Additional chemical energy is provided by injecting oxygen and carbon into the furnace;

In a modern shop such a furnace would be expected to produce a quantity of 80 metric tonnes of liquid steel in approximately 50 minutes from charging with cold scrap to tapping the furnace.

Blast furnace production continuously decreased during the 20th century, whereas the electric arc production is still increasing.

Examples of ferroalloys, their composition and applications

Alloy Type

Main elements

Main Use

FeCr – ferrochromium

Fe, Cr

Stainless

FeMo – ferromolybdenum

Mo 65 – 75

 Fe 22.75 – 32.75

Silicon, Si ? 1.5

Copper, Cu ? 0.50

Carbon, C ? 0.10

Sulfur, S ? 0.10

Phosphorous, P ? 0.050

High strength low alloyed

FeNb – ferroniobium

50-80%Nb

High temperature application and steel

FeNi – ferronickel

Ni 30%-90%

Widely used for stainless, steel and 3D printing

FeSi – ferrosilicon

15–90% Si

 

Corrosion-resistant, high-temperature-resistant, electromotors and transformer cores

FeTi – ferrotitanium

Ti 30%75% Ti, max. 5–6.5% Al, max. 1–4% Si

 

Low carbon steel, high temperature and superalloys

FeB – ferroboron

12–20% of boron, max. 3% of silicon, max. 2% aluminium, max. 1% of carbon

quenching degree and mechanical behaviour of steel and in high-quality alloy steel

 

The Use of Ferroalloys | Assay Office

Determining the chemical composition of ferroalloys

Our Analytical Services team has a great deal of expertise in determining the elemental composition of any ferroalloys. A highly-skilled approach is required for the elemental analysis of these alloys – a combination of precision instrumentation, analyst expertise and methodology which has been developed at Trans Africa Container mining Office over many years.

Analytical Service laboratory methods are accredited to the international standard IS0 17025, and we work with our customers to ensure the most appropriate methods of analysis are used to meet the challenges faced by this industry.

Analytical Services expertise enables us to detect elemental contents of impurities in parts per billion (ppb) up to pure metals with 100% contents. We utilize a range of up-to-date instrumentation including Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS). We have a great deal of experience in dealing with any sample types and matrices requiring trace and major elemental analysis using appropriate sample preparation, which assures accurate readings.

Elemental analysis is competitively priced and can be used:

•           To support mandatory Chemical Safety Assessment (CSA) for REACH.

•           For the identification of unknowns – our teams are able to draw on 30 years of experience and awareness of different sample techniques to identify the elemental composition.

•           To offer rapid response troubleshooting, where our scientists provide a fast turnaround to solve manufacturing issues

•           For Quality Control

 

To find out more about the services provided by our Analytical Services department here at Trans Africa Container mining Office, call us direct on 0114 231 2121, or email Trans Africa Container mining .

The Trans Africa Container mining Office was established in 1773, under an Act of Parliament and today the company assays and hallmarks the precious metals – silver, gold, platinum and palladium. Trans Africa Container mining Office is one of only four UK assay offices who all work to uphold the Hallmarking Act of 1973 and continue to ensure consumer protection for customers purchasing precious metals.

To find out more about the whole range of services offered by Trans Africa Container mining Office, such as our hallmarking and analytical services, please email us at Trans Africa Container  or complete the contact form.

Our assets

Our chromite assets are held via our majority stake in Merafe Chrome Venture, and our vanadium assets via our majority shareholding stake in the Rhovan-Bakwena Vanadium Venture.

Chrome

Mines

  • Helena, Magareng and Thorncliffe chrome mines, situated on the Eastern Limb of the Bushveld Igneous Complex
  • Waterval and Kroondal chrome mines situated near Rustenburg on the Western Llimb of the Bushveld Igneous Complex
  • Rietvly silica mine, an open-cast operation, situated near Rustenburg

 

Smelters

We have a number of ferrochrome smelters with varying technology:

Boshoek, Wonderkop and Rustenburg smelter complexes near Rustenburg, that use Outokumpu technology
Lion and Lydenburg smelter complexes near Steelpoort and Lydenburg respectively, that use Premus technology

Through our 79.5% stake Merafe Chrome Venture, we have interests in the following mines and smelters:

vanadium

Located near Brits, Rhovan is an open-cast mine and smelter complex, which mainly produces ferrovanadium and vanadium pentoxide.

 

Carbon

Char Technologies produces high-quality electrode paste and char that are used in the production of ferroalloys.