Boron is everywhere. It is one of the 109 elements that make up the planet and is fundamental to life. It is found in trace amounts in water, soil, plants, animals and the food we eat. Millions of tonnes of industrial borates are mined, processed and shipped round the globe every year and twice that volume of boron is moved by nature through volcanic activity and dissolved in rain.
Occurrence of Borax
In nature, boron combines to form boric acid and inorganic salts called borates and does not exist by itself. Borax is a form of hydrous sodium borate that occurs in and regions, forming from the evaporation of saline lakes. It is also synthesised as a by product of borate deposit mining. It is normally colourless, white or light grey, but can be tinted light shades of blue, green and yellow Naturally occurring borax is translucent due to water in its structure, but develops a white powder on its surface as the water evaporates. The name borax comes from the Arabic ‘buraq’ meaning ‘white’.
Figure 1. Borax
Discovery and First Application
Borax is also known as tincal, from the Sanskrit word for the mineral, and the first deposits were discovered in Tibet in dry lake beds. In the 8th Century AD tincal from these deposits was transported in ancient caravans along trade routes now called the Silk Road. This was also the time of the first confirmed use of borax by Arabian goldsmiths and silversmiths.
Applications in Ceramics and Glazes
In China in the 10th century AD, borax was used in ceramic glazes. The mineral is still used in modern ceramics to ensure a good fit between the glaze and the clay and to increase durability and shine. Borates have also recently been added to tile bodies to lower energy use during production.
Main Sources of Borates
Most of the world’s borates today come from the southern United States. In 1872 F M Smith, the founder of The Harmony Borax Works (now known as Rio Tinto Borax), discovered borates in the Nevada desert and by 1883 had established 20 mule teams to haul the minerals out of Death Valley More than 130 years on, the company is still one of the world’s largest producers of borates, meeting 43% of world demand.
Applications of Borax
Borax has myriad uses in the modern world, both at home and in industry. In the home borax is used as a laundry detergent booster, cleaner, preservative, fungicide, insecticide, herbicide, disinfectant and dessicant. In industry borax is used as a buffer, a dispersal agent, welding flux and to control viscosity.
Borates modify the structure of glass to make it resistant to thermal or chemical attack. They are used in the production of ultra-thin LCD screens, heat resistant glass and fibreglass and account for 43% of world demand for these products. They also interact with ferrous surfaces to form a coating that protects the metal from corrosion. Combined with zinc, borates are used as flame retardants in the polymers used to coat electrical cables and in cellulose insulation. Borates can even be used as a nuclear containment shield.
One major area of borate research in the US is the development of safe and durable wood preservatives. Wood is increasingly used as a building material because it is a recyclable, sustainable resource, but it is prone to biological attack. Damage caused by the Formosan termite costs American homeowners US$1 billion every year. Pesticides applied to soil are ineffective because the termites nest above ground, so the building itself needs to be treated. Borate treated building products are cost-effective measure to keep voracious termites at bay.
Borax is a star on the rise. The demand for boric acid in borosilicate is increasing, and producers of reinforcement fibreglass and ceramic glazes are using increasing boric acid concentrations to lower energy use and improve product performance. Indeed, researchers at the University of Florida recently discovered that borates were essential in converting interstellar dust clouds into ribose one of the building blocks of life - so borates may even be the key to unlock the great mystery of how life on Earth began.