An introduction to arsenic

Arsenic demand and end-uses

Arsenic demand is influenced by its applications across various industries and is subject to strict regulatory oversight due to its toxicity and potential environmental impact. As a result, industries are continually seeking safer alternatives or ways to minimize arsenic use while maintaining the benefits it provides. This has led to a dynamic market where demand can fluctuate based on regulations, technological advancements, and shifts towards more sustainable practices. Key areas driving arsenic demand include agriculture, wood perseveration, semiconductor manufacturing, glass manufacturing, alloying and medicine.

Semiconductor Industry: Arsenic is essential in the production of gallium arsenide (GaAs), a semiconductor used in microelectronics, LED lights, and solar cells. GaAs is prized for its efficiency in converting electricity into light and vice versa, making it valuable for certain high-frequency and high-speed electronic devices.

Glass Manufacturing: Arsenic is used in the production of speciality glass products. It helps remove bubbles and improve the clarity of glass, playing a role in the manufacturing of high-quality glass for various applications.

Alloying Agent: Arsenic can be added to lead and other metals to improve their properties. For example, it is used in lead alloys for car batteries, enhancing the strength and charge retention of the batteries.

Medicine: Some arsenic compounds have medical applications. For example, arsenic trioxide is used in the treatment of certain types of leukaemia, highlighting its role in pharmaceuticals.

Wood Preservation: Arsenic compounds, particularly chromated copper arsenate (CCA), have been used as preservatives to prevent rot in timber. The demand in this sector has fallen in residential applications in many countries but may persist in industrial settings.

In agriculture, historically, arsenic compounds were used in pesticides, herbicides, and insecticides. Although the use of arsenic in these applications has decreased significantly in many countries due to environmental and health concerns, some regions may still use arsenic for pest control in agriculture.

Arsenic supply

Arsenic production is closely tied to the processing of minerals and ores from various mining operations worldwide. Primarily, arsenic is obtained through the treatment of copper, gold, and lead smelter flue dust. Additionally, roasting arsenopyrite, the most prevalent arsenic-bearing mineral, is a common method of extraction.

Significant recovery of arsenic also comes from orpiment and realgar, especially in Peru and China. These minerals are often associated with gold mining activities, where arsenic is a by-product. In the Sichuan Province of China, arsenic is extracted from these minerals sourced from gold mines.

Chile is noted for its production of arsenic from copper-gold ore processing, while in Canada, arsenic is often found in conjunction with gold mining operations. The recovery of arsenic from copper minerals, such as enargite, represents another source of this element.
In Morocco, arsenic is produced as cobalt-arsenide from the Bou Azzer mine, highlighting a unique method of arsenic production. Moreover, the Guernmassa hydrometallurgical complex in Morocco is known for producing arsenic trioxide, further diversifying the global sources and methods of arsenic production.

Arsenic substitution

In mid-tier third-generation cellular handsets, silicon-based complementary metal-oxide semiconductor (CMOS) power amplifiers are emerging as competitors to GaAs (gallium arsenide) power amplifiers. The semiconductor industry is witnessing a shift from GaAs and silicon-based lateral diffused metal-oxide-semiconductor (LDMOS) field-effect transistors (FETs) to those using gallium nitride (GaN). Indium phosphide (InP) components offer an alternative to GaAs-based infrared laser diodes for specific wavelength needs, while helium-neon lasers present competition to GaAs in applications requiring visible laser diodes. Silicon stands as a principal rival to GaAs in solar cell technologies.

Despite these advancements, GaAs-based integrated circuits remain irreplaceable in many defence applications due to their distinct properties. However, in certain uses of heterojunction bipolar transistors (HBTs), silicon-germanium (SiGe) is beginning to replace GaAs, indicating evolving preferences and technologies in semiconductor applications.

There are several other wood preservatives to chromated copper arsenate (CCA), such as alkaline copper quaternary (ACQ), ammoniacal copper quaternary (ACQ), ammoniacal copper zinc arsenate (ACZA), boron-based ACQ preservatives, copper azole, copper citrate, and copper naphthenate. For replacing treated wood, options like concrete, plastic composite materials, recycled plasticized wood, and steel are available.