Arc furnaces – Puremelting, Inc

The silicon carbothermal recovery by open bath arc furnaces

Open bath furnaces are commonly used in the recovery of metallurgical silicon from silicon-containing ores or by-products. This method utilizes high-temperature processing in an open atmosphere, where silicon dioxide (SiO₂) is reduced by carbon, typically in the form of coke or charcoal. The process occurs in a furnace with an exposed, unsealed bath of molten material, allowing gases to escape freely. These types of the furnaces traditionally applied to recover the ore. The typical example is carbothermal recovery. This process is conducted by the high temperature caused by arcs.

Metallurgical silicon (Si) is an essential material in the production of aluminum alloys, solar panels, and various electronic applications. The carbothermic reduction method is one of the most common processes used for silicon recovery. This process involves the use of carbon, usually in the form of coke or charcoal, to reduce silicon dioxide (SiO₂) at high temperatures to produce silicon. The carbothermic reduction of SiO₂ occurs at temperatures of 1700°C to 2000°C, where silicon dioxide reacts with carbon to produce metallurgical-grade silicon and carbon dioxide. Carbothermic reduction of silicon dioxide is a cost-effective and widely used method for producing metallurgical-grade silicon. The process is simple but requires precise control over temperature, carbon quality, and energy input. While the method yields a high volume of silicon, its applications are often limited to industries that do not require the highest purity silicon. Further purification steps are necessary for more demanding applications such as in solar cells or semiconductors.

The steel melting and recovery by arc and blast furnaces

The steel slabs in many regions come from the secondary market where the electric arc furnace is applied to recover the steel rod. The steel from the secondary market needed to be shredded and dried enough to not cause any explosions while melting. This type of the furnaces applied the current between the electrode and load. The ore recovery is not processed by these types of the furnaces due to the heating method. The ferrous metals industry is driven mostly by infrastructure and machinery applications, which leads the Africa, South America and Association of Southeast Asian Nations. The recent research investigated the market opportunity and sustainable manufacturing challenges.

Link to original – https://www.nature.com/articles/s41467-021-22245-6

General flow diagram of Iron – Steel making process

Steel recovery involves two main methods: extraction from iron ore and recycling of scrap steel.

Steel Recovery from Ore. Steel is primarily produced from iron ore through a process known as the blast furnace method. In this process, iron ore (mainly Fe₂O₃ or Fe₃O₄) is reduced by carbon (coke) at high temperatures (around 1500°C), producing molten iron and carbon monoxide. The molten iron is then refined in a basic oxygen furnace (BOF), where oxygen is blown in to remove impurities like carbon, yielding steel. Steel Recycling. Recycling involves melting down scrap steel in an electric arc furnace (EAF). This process is more energy-efficient and environmentally friendly compared to ore extraction, as it requires less energy and reduces CO₂ emissions. The scrap steel is melted, impurities are removed, and the metal is refined to produce new steel products.

Steel Making Process In steel production, a blast furnace is used to convert iron ore (mainly iron oxide) into molten iron. The furnace operates at high temperatures (around 1500°C), where coke (carbon) is used as a reducing agent to extract iron from its ore. The process also involves adding limestone to remove impurities, producing slag. The molten iron is then refined in a basic oxygen furnace (BOF) to create steel.
E-Waste Processing Blast furnaces can also be used for recycling metals from e-waste. In this process, materials like circuit boards and other electronic components are treated in the furnace to recover valuable metals such as copper, gold, and silver. The high heat of the furnace helps separate metals from plastics and other materials. However, e-waste processing requires careful handling to prevent the release of toxic substances

Link to original material – https://www.researchgate.net/publication/338186862_iron-steel_making_From_start_to_finish

The cold heart arc furnaces

The trend for the steel industry is sustainable recycling due to significantly lower power consumption and requirements for the infrastructure. The steel manufacturing process becomes more and more decentralized and more technologies become available on the market. The best trend I see is the cold heart plasma furnaces that have lower power consumption and better eco standard.

The main idea of my article is to review the new type of arc furnaces. I called them the cold electrode furnaces. The eco standart, power consumption and financially stable produced products. The furnace can do ore recovery, steel recycling and high melting point metals melting such as titanium. The plasma heating due to power consumption and produced materials is one of the best trends I saw on the high melting point metals and steel recycling market.

For the melting and remelting of Alloys (e.g. Titanium Alloys, Titanium Aluminides) which contain larger amounts of alloying elements with high vapor pressure that would evaporate under deep vacuum conditions, the plasma arc melting process (PAM) is the first choice. Using plasma arc melting, the metal is melted under an inert gas atmosphere (usually Helium or Argon) in a pressure range between 400 – 1,200 mbar abs. The plasma arc torch column provides the heat source with maximum temperatures well above 15,000 K. Under these process conditions evaporation of alloying elements can be suppressed and complex alloy compositions can be produced.

Link to source – https://www.ald-vt.com/portfolio/engineering/vacuum-metallurgy/plasma-arc-melting-furnace/