Specialty Metals and Minerals – Antimony
Read the prologue to specialty metals and minerals here.
Antimony has been used for thousands of years. Antimony sulphide (stibnite) was used as a cosmetic, as long ago as 3,000BC, in Sumer (today’s south-central Iraq) and Egypt. The sulphide was finely ground and applied to the eyes and eyelashes. Much later its use as a cosmetic spread to many countries and it became known in Hebrew and Arabic as kohl. In other languages kohl was spelt “alcool” or “alkohol” and up until the Middle Ages “alcohol” referred to anything in the form of a fine powder.
A number of references state that a vase dated at around 3,000BC was discovered at Tello, in Sumer, that was cast in “metallic” antimony. References are also made to antimony plated objects in Egypt at around the same time.
Antimony was integral to the practice of alchemy, particularly in its later stages of the 17th century. It has also been used as a medicine and as a poison.
Within the periodic table of the elements, there is a continuum from non-metals to metals. Antimony lies somewhere within the middle of the range and is often referred to as a metalloid; that is, it is metallic looking, brittle and able to alloy with metals. Related elements are boron, silicon, germanium, arsenic and tellurium.
Metalloids, or their compounds, can all be used as semiconductors. For example, with regard to antimony, gallium antimonide is used in infrared detectors, LED’s and thermophotovoltaics and indium antimonide is used in thermal imaging sensors.
Antimony is a silvery grey colour that can exist in nature as the metal, but almost always occurs as the sulphide, stibnite (Sb2S3). A particularly beautiful example is shown below.
Stibnite from the Wuling Antimony Mine in China
This crystal cluster is for sale at irocks.com for USD23,500.00
There are dozens of antimony compounds in industrial use today. However the vast majority of antimony is consumed as antimony trioxide (“Sb2O3”, “ATO”), antimony metal, secondary antimonial lead and sodium antimonate.
ATO is an important component of flame retardants. Retardants are mostly used in electronics and plastics, and also in fabrics such as clothing and upholstery. Flame retardants account for about 50% of the world’s antimony consumption, and market share continues to grow.
Around 25% of world antimony consumption is in lead acid batteries. The antimony is sourced from new metal supply and from secondary antimonial lead from the recycling of batteries. Antimony is added to strengthen and harden the lead. However, the weight percent of antimony in a lead acid battery is in continuous decline and antimony metal use will also be impacted by alternative battery technologies.
Antimony metal is used in a number of other lead alloys. For example, it is important in lead bullets as it allows the correct expansion of the bullet into the rifling, thus improving accuracy and range. In general, more antimony is used in higher speed projectiles.
Sodium antimonate is used as a high temperature oxidant, in fire proofing, and in glass refining and decolourising. Antimony compounds are also used in paints and pigments.
A new generation of memory devices is being developed that will replace the flash drive memory devices presently used in computers and mobile phones. These “phase change devices” use an alloy of germanium, antimony and tellurium.
Substitutes & Recycling
Antimony can be readily substituted in batteries, paints and pigments. Some hydrocarbons and hydrate aluminium oxide are already used to reduce the usage of ATO in flame retardants. Antimony is traditionally recycled from batteries but not from flame retardants, although when plastic is recycled so is the antimony, if inadvertently.
The first spike in the antimony price was during the First World War, because of the extreme consumption of bullets and related ammunition. Prices and production quadrupled before settling back to pre-war levels at the cessation of hostilities. Similar spikes were also seen during the Korean and Second World Wars.
During the 1980’s and until the early 1990’s, China increased production until it was again supplying around 90% of the world’s market, as it had during the First World War. This supressed the antimony price, which stagnated until around 1999. For China, which was then running a trade balance deficit, antimony (and many other commodities) earned valuable foreign exchange reserves. For other countries, the depressed price led to declining production and cessation of exploration.
By 2000 the price of refined antimony had fallen to around UDS $1,500 per tonne, its lowest level since 1970. This made much Chinese production unprofitable, so the Chinese government took several steps to reduce the production and export of antimony. This worked. The price of antimony soared to a peak of around USD17,000 per tonne in 2011 and was around USD9,570 in 2014.
Supply and Demand
The United States Geological Survey (“USGS”) estimates that world mine production of antimony metal in 2014 was 160,000 tonnes. China supplied about 80% of this total, of which 60% was from Chinese mines and the balance derived from imported metal concentrates. The minor producers are Bolivia, Russia, South Africa, Tajikistan and Turkey.
Much of China’s antimony exports are as ATO rather than the metal. China itself is a large antimony consumer through both domestic consumption and export of antimony in manufactured products. Antimony, along with rare earths and tungsten, is a strategic metal for China and is therefore subject to export quota (read more about strategic minerals/metals here). This, along with mine closures for environmental and depletion reasons, and forced smelter consolidations, has significantly tightened supply since 2007.
In 2014, USGS estimated world reserves of 1.8 million tonnes of antimony metal. China hosted over 50% of this reserve. Bolivia and Russia host about 20% each.
The world’s reserves of antimony are small, perhaps enough for 10 to 15 year’s consumption at current rates. But a number of mines, including the world’s biggest (Twinkling Star in China), are mostly depleted. So ten year’s supply will be optimistic without new production.
Australia hosts five significant antimony deposits, two of which are in operation, along with hundreds of small deposits and prospects, most of which have barely been explored.
Antimony is toxic. It occurs naturally in water and on land and passes relatively quickly through an animal. However, antimony toxicity is a complex area as some antimony compounds are much more toxic than others. Antimony is often found, both in nature and industry, in combination with other potentially toxic compounds, which can make it difficult to determine the actual cause of poisoning.
This is a major negative that results in heightened environmental concerns.
The investment opportunity is that tightening supply will lead to higher prices, which in turn will spur exploration and development.
However there are limited opportunities in the listed space. The largest Australian deposit, Hillgrove, is held privately. Costerfield is owned by Mandalay Resources Corporation (TSXV:MND, Market Cap CAD331M). Both Hillgrove and Costerfield are in production.
Three Australian juniors own the remaining significant deposits.
- Artemis Resources Limited (ASX:ARV, Market Cap AUD1.3M) holds the Mt Clement deposit
- Anchor Resources Limited (ASX: AHR, Market Cap AUD1.3M) holds the Wild Cattle Creek deposit
- Northwest Resources Limited (ASX: NWR, no longer listed) holds the Blue Spec deposit. NWR is in the process of selling Blue Spec to Novo Resources Corp. (TSXV: NVO, Market Cap CAD52M).
With any sustained rise in the antimony price, I would expect to see these and other deposits and prospects win prominence in the listed space.