Mercury ready to stage comeback

After a long period of declining consumption, mercury may be in for a reversal in fortunes. London- based Roskill reports it sees the prospect of a plateau in demand for the mineral in the U.S. and a modest growth in demand in much of the rest of the world except Japan.

Mercury has been in plentiful supply for several years because of the widespread availability of redistilled mercury from redundant industrial processes and to poor growth in demand, reflecting concern over the toxicity of mercury released into the environment from the industrial end-uses in which it is consumed. By September, 1986, mercury was selling for $170 per flask (34.5 kg) in the U.S. and $115 per flask in Europe, its lowest free- market prices for almost 10 years.

Weak demand forced the closure, in early 1987, of the McDermitt mine in the U.S., that country’s only mercury mine. The Idrija mine in Yugoslavia also came under scrutiny.

Prices rallied, however, with Spanish producer Minas de Almaden y Arrayanes S.A. (whose output accounts for about half of the non-Communist world’s prime virgin mercury production) leading the way towards its target producer price of $400 per flask. By September, 1987, prices had recovered to $330 per flask in the U.S. and $280 per flask in Europe.

World production of prime virgin mercury has been close to 200,000 flasks (6,500 tonnes) annually since 1977, with a 10-year peak of 210,300 flasks recorded in 1986. Production is divided almost equally between the non-Communist world, the U.S.S.R, Eastern Europe and China. Mercury batteries

The principal end-use for mercury is in the manufacture of batteries. The U.S. consumes more than 1,000 tonnes per year in this end-use alone. The standard mercury battery is an akaline dry cell with a mercury oxide cathode; it exhibits a relatively flat discharge curve, a constant voltage, a long shelf life and functions well from low to high temperatures. Because of the compactness and performance characteristics of these batteries, they are widely used in hearing aids, calculators, watches and cameras.

Spent batteries are a source of secondary mercury which can be recycled. Roskill says the scale of recovery of secondary mercury, not well documented, is probably in the order of several hundred tonnes per year.

Until the 1960s, the principal end-use for mercury was as the flowing mercury cathode for the electrolysis of brine to yield chlorine and caustic soda.

As mercury-cell plants are closed, their mercury is redistilled and sold for other uses. Western world chlor- alkali capacity is about 33 million tonnes per year of chlorine, of which some 12 million tonnes per year is still mercury-cell capacity. This capacity contains about 300,000 flasks of mercury, equivalent to some three years of Western world production of prime virgin mercury. Plant closures

A minimum of 30,000 flasks of redistilled mercury was returned to the market from closures of Japanese chlor-alkali plants alone in 1986, but this type of plant has now been completely eliminated in that country; closures elsewhere in the world now occur at a slower pace than that which occurred in Japan.

World demand for prime virgin mercury is forecast to rise by 1.2% per year to 7,200 tonnes in 1990 and 8,130 tonnes in the year 2000. World reserves, tentatively placed at 136,000 tonnes, are adequate, and Roskill says many mines closed in recent years could be tempted to reopen if any growth in demand is translated into favorable prices. However, recycled mercury is expected to meet an increasing proportion of demand, with consumption forecast to grow at 2.5% per year to 1,000 tonnes in 1990 and almost 1,300 tonnes in 2000.

Key factors that will influence the future mercury market include growth in consumption of mercury batteries, closure of further mercury-cell chlor-alkali plants and disposal of the supplies of redistilled mercury which these closures will provide, sales of mercury to the West from Eastern bloc countries and a degree of success achieved in reaching the target set by Almaden for a producer price for mercury.

Environmental issues concerning mercury are now well appreciated and largely accommodated, and Roskill points out the threat of large-scale environmental pollution by release of mercury from industrial processes has been effectively removed, and will have little impact on the future of the mercury market.