<strong>Production</strong> of kaolin tonnes Country 2002 2003 2004 2005 2006 Australia (d) (f) 228 000 280 000 285 543 231 611 182 304 New Zealand 17 250 14 770 15 250 15 750 14 864 <strong>World</strong> Total 23 400 000 23 900 000 24 800 000 25 300 000 25 100 000 Note(s):- (1) In addition to the countries listed Denmark is believed to produce kaolin (a) Sales (b) Years ended 7 July of that stated (c) Years ended 31 March following that stated (d) Years ended 30 June of that stated (e) Sold or used by producers (f) Excluding New South Wales (g) Washed and dried (h) Beneficiated (i) Beneficiated; excludes directly used natural kaolin (j) Years ended 20 March following that stated (k) Washed (l) Dry weight 52
LEAD Characteristics Lead is a dense (11.34 g/cm 3 ), bluish-white metal with little mechanical strength and virtually no elasticity. It is extremely soft and highly malleable, with a low melting point (327.4ºC). When freshly cut the surface has a metallic lustre, but this quickly tarnishes to dull grey when exposed to air due to oxidation. It has poor electrical conductivity compared to other metals. Lead is a potent neurotoxin that accumulates in soft tissues and bone over time, and this has lead to increasing restriction in its usage in recent years. Lead is rarely found as native (free) metal, but is usually extracted from sulphide ores in which the most common lead mineral is galena (lead sulphide; PbS). It is usually found in association with other sulphide minerals also used as ores, most frequently those of zinc and copper, but also precious metals. Silver commonly occurs in galena both in solid solution and as a sulphide phase. Galena is the chief source of commercial silver output. Other economic lead ore minerals include cerussite (lead carbonate; PbCO3) and anglesite (lead sulphate; PbSO 4), commonly found as weathering products overlying sulphide ore bodies. In terms of mine output lead is almost always a co-product with other base metals Lead is obtained from galena by a process called smelting. This involves roasting the ore to remove the sulphur and to obtain lead oxide, which is then reacted with coke in a furnace. The resulting lead bullion contains many impurities such as silver and gold (hence the name bullion) as well as antimony, arsenic, copper, tin and zinc. These impurities are then removed by various refining steps to obtain pure lead (Lead Development Association International, 2008). <strong>World</strong> reserves of lead are 79 million tonnes (Mt), of which Australia holds 24 Mt, China 11 Mt and USA 7.7 Mt. Uses Current global use of lead (Ellis, 2007): • lead-acid batteries 77% • pigments 8% • rolled extrusions 6% • alloys (including casting) 3% • shot/ammunition 2% • cable sheathing 1% • miscellaneous 3% The most important use of lead is in lead-acid batteries which provide ancillary electrical power (chiefly for starting) in virtually all road vehicles and also in electrically-driven vehicles. They also provide emergency power in the event of power failure. Lead’s softness and low melting point make lead very easy to work hence it has a long history of exploitation. Its high resistance to corrosion makes it ideal for weather-proofing buildings and for equipment used in the manufacture of acids. Lead's high density means that it absorbs radiation and noise. It is thus used as radiation shielding in medical applications and the nuclear industry, and in sound-proofing. Lead chromate (yellow) and lead molybdate (red/orange) are used as colouring pigments for ceramic glazes, plastics and to a lesser extent under current legislation, paints e.g. in road paint. Lead oxide (PbO) in glass reduces the transmission of radiation, and glasses for VDU equipment may contain up to 28 per cent PbO (Lead Development Association International, 2008). Other minor uses include weights and molten lead is used as a coolant in fast reactors. Owing to its toxicity, lead use has become more strictly regulated and restricted over the last 30 years. Initially, the change was due to the requirement of US lead consumers to comply with environmental regulations which significantly reduced or eliminated the use of lead in non-battery products, including as a petrol additive, in paints, solders, and water systems. Lead use is being further curtailed by the European Union’s RoHS Directive which came into force on 1 July 2006. Lead may still be found in harmful quantities in stoneware, vinyl (such as that used for tubing and the insulation of electrical cords), and in brass manufactured in China. Throughout 2006–2007, many children's toys made in China were recalled due to lead in paint used to colour the product; e.g. the toy firm Mattel recalled 55 000 Chinese-made toys in the US after lead contamination fears (BBC News, 25 October 2007). <strong>World</strong> production in 2006 <strong>World</strong>wide production of refined lead was eight million tonnes in 2006; a 19 per cent increase over 2005 production. <strong>Production</strong> increased steadily during the period 2002 to 2006, with an overall increase of 16 per cent, although levelling out in 2005. China is the top-producing country with 2.7 million tonnes in 2006. This represents a 14 per cent increase on 2005 and a 106 per cent increase since 2002. The USA was the second largest producer with 1.3 million tonnes and Germany, third, with production of 0.3 million tonnes. The reliance on reliance scrap metal recycling is increasing, and in 2006 about 50 per cent of refined lead was produced this way. In the ‘western’ world today more lead is produced by recycling than by mining (Lead Development Association International, 2008). Primary (mined) lead production is dominated by China, Australia and the USA, which together account for more than half of the total. Prices Lead prices started to increase in 2006 after a period of relative price stability at around US$500 per tonne through the 1990s up until 2003. Prices had doubled by mid-2006 before the rate of increase began to escalate more dramatically. In 2007 the London Metal Exchange (LME) official price for lead set record highs, reaching an all-time high of US$3980 per tonne on 15 October as a result of concerns about tight supplies and expectation of continuing growth in demand. At the beginning of October, LME stocks stood at just 22 000 tonnes sufficient for less than one day’s global consumption, and the squeeze on supplies available for immediate delivery showed no signs of easing (Ellis, 2007). Prices rose dramatically in response to the suspension of production at Toronto-based Ivernia Inc.’s Magellan Mine in Western Australia in March 2007 (Ellis, 2007). This mine remains the world’s only pure primary lead mine. Output was suspended after contamination at the Port of Esperance, where Magellan routes all its exports, when thousands of seabirds died from lead poisoning. The company was officially blamed for the contamination in September 2007 (Parliament of Western Australia, 2007). Supplies to the world market were further disrupted by an explosion at Doe Run Resources Corporation’s Herculaneum smelter in Missouri, USA, which was reported to have halved production (Mining Journal, 20 July 2007). 53
Change language