Hgh quality local raw materials underpin the local manufacture of silicon eroded by the energy-intensity.
Silicon is used in metallurgical and chemical applications for which different quality products are required.
Metallurgical grade silicon is used for producing alloys with other metals such as aluminium. It has the effect of strengthening and hardening aluminium to improve its suitability and resistance to heat for specific applications. Silicon is used in the production of both primary and secondary alloys where only the highest purity of metallurgical silicon is required to produce primary alloys.
Chemical grade silicon is used in the production of silicone. Silicone is the precursor used in the production of commonly used products such as polishes, lubricants, greases, hydraulic fluids, insulators, semi conductors, adhesives, medical implants, medical and surgical aids, cosmetics, paints, silicon chips and photovoltaic or solar cells. The major users of chemical grade silicon require product qualities to meet their specific process needs.
Since the early 1980's western world consumption of silicon has grown at an average annual rate of 5% with the largest driver of growth being demand from the chemical grade market. Industry experts are forecasting continued growth into the next decade with the stronger growth in demand from the chemical industry. International research and analysis of western world silicon demand and supply, suggests that about a 30% increase in western world silicon capacity is required by 2005 to adequately satisfy demand.
Simcoa Operations operates the only silicon producing smelter in Australia at Kemerton, adjoining the MIC pigment plant. Since 1996 it is owned by the Japanese Shin-Etsu Chemical Company which has interests in the manufacture of silicon and silicones.
The plant was commissioned 1989-90 by Barrack Mines. The plant had accumulated debts of $170m when acquired by Deutsche Bank in 1995 at which time it had a replacement value of $120m (and believed to be purchased well below even that value). During this period, the price of silicon had declined from US$2 000 to US$1 100 per tonne (having since recovered).
Production of silicon is about 26 000 tonnes per year (capacity of 34 000 tonnes) valued at round $45 million. It produces a range of silicon grades, predominantly a 99.5 per cent grade.
Typically about one-quarter of the sales are to eastern Australia and New Zealand for use in the metallurgical industry, about one-third of exports for metallurgical purposes and the balance (ie. half of total production) for chemical applications (ie. principally for the manufacture of silicones). About 90 per cent of the silicon is exported through the Fremantle port with the 10 per cent balance freighted to eastern Australian markets.
About 10 000 tonnes of silica fume is also produced and sold as an additive for high performance concrete. (Silica fume is also produced by AFM).
The comparative advantage of the Simcoa plant is derived from the two principal raw materials, silica and wood. High purity quartzite is freighted 340 km from Moora, (180 km north of Perth) and jarrah timber from nearby forests.
About 60 000 tonnes of quartzite (about 45 per cent silicon) and 25 000 tonnes of charcoal (made from 90 000 tonnes of timber) are required to produce the 28 000 tonnes of silicon. In other words, the competitive manufacture of silicon is helped as the raw material inputs are three-times the mass of the finished product representing substantial freight cost savings.
Charcoal is required to reduce the silica to silicon (ie. SiO2 + 2C = Si + 2CO) - a process that is sensitive to its quality. (The carbon also acts as a conductor in the electric arc furnace and a reaction bed). Though their competitors generally use a low ash coal (metallurgical grade coal is not available in western Australia), Simcoa uses charcoal made from jarrah wood. Jarrah is considered to provide a superior form of charcoal (low ash content, uniform grade with a high ignition temperature).
The process is very energy intensive requiring about 13 megawatt hours of electricity to produce one tonne of silicon. At the industry standard of A$0.06 per kWh, electricity represents around 40 per cent of the market value of silicon. Silicon production is therefore the most energy-intensive operation in Western Australia comparable to the manufacture of aluminium. The energy cost penalty is offset by access to competitive raw materials (ie. wood [charcoal] and silica).
The company claims despite discounted access to electricity (from the Muja coal fired power station), three-quarters of its competitors have access to cheaper power (and it has threatened to build a new plant in eastern Australia).
Is an energy-intensive process normally suited to low cost energy centres that is offset in Western Australia by cost saving access to wood and silica. Its future is closely related to the discounts it can negotiate with the electricity supplier (a public subsidy for a plant with insufficient comparative advantage).
Other silicon chemicals
The manufacture of high purity charcoal suggests potential for high quality activated (commonly with steam) carbon used in the gold extraction industry. (Though the carbon is of a specific form and hardness that is commonly produced from coconut shell, there are price premiums for superior-performance forms. The prospects for manufacturing special grades of carbon are described.
Producing charcoal from timber generates substantial amounts of pyroligneous tars and volatiles that are recycled as fuel by Simcoa. Whereas up to 10 per cent by weight of wood tar is produced, the only one-time commercially viable by-products are methanol, methyl acetate and acetic acid (as once produced at Wundowie, east of Perth) that are now more cheaply produced in large scale petrochemical plants.
High purity silicon
The silicon produced by Simcoa is suitable for metallurgical purposes and for the manufacture of silicones. Semi-conductor devices require an even higher purity form of silicon than produced by Simcoa. Such grade of silicon is normally produced by its conversion to silanes (being organochlorine derivatives of silicon as used in the production of silicones) and then distilled and pyrodecomposition to silicon metal. Given the proximate location of the chloralkali plant, that produces both chlorine for the SCM plant and hydrogen as a currently low value by-product, the prospect for adding value to the silicon by further purification should be evaluated. It is worth noting that the
Silicones are used as greases, sealants, adhesives, coatings, and chemical specialties. Silicones are produced in many locations by some seven major companies using technology that is not freely available.
Silicones are produced from silane monomers (including methyl-, ethyl-, phenyl-chlorsilane), from which silicone compositions are produced by hydrolysis. Until the early 1980s, Dow Corning produced silicones in Australia from partly manufactured silane monomers imported from its blank company in the USA. The reduction in the levels of import tariffs led to the closure of the plant confirming the Australian market is simply too small to support local manufacturing without a substantial comparative advantage. It is useful to note that the current owner of Simcoa has interest in silicone manufacturing operations in Asia.
Activated and fumed silica
Activated silicas are high surface area silicas used as fillers, drying agents, carriers, for fusing to high performance optical lenses. Fumed silica is used for similar applications and in rubbers, plastics, paints and adhesives. World consumption of such silica is in excess of 1 million tonnes p.a. valued at around A$1500 per tonne.
About 40 percent of the quartz starting material is converted to “silica fume”, a solid aerosol, with particle size less than 1 micron, comprising mainly silicon dioxide and some flux-wood ash. There are conflicting reports on whether the silicon dioxide particles in the silica fume are entirely amorphous silica, which is relatively harmless; or whether containing up to 10 percent crystalline silica which is carcinogenic.
Production may be from;
Silicon tetrachloride reacted with oxygen and hence broadly similar to the titanium dioxide operation (adjoining the Simcoa silicon plant). The silicon tetrachloride is produced from silicon with hydrochloric acid or silica with chlorine and carbon. From sodium silicate reacted with hydrochloric acid where the sodium silicate is produced by reacting silica with caustic soda at high temperatures.A typical plant would produce around 10 000 tpa largely for export. It is relevant to note that Western Australia has large deposits of high quality silica.
The world market for fused silica is about 200 000 tpa of which 60 per cent is for the electronics industry growing at 20 per cent per year. The other market is for precision investment casting (ie. avoiding machining costs) growing at 6 per cent.
Fused silica is manufactured by the fusion of high quality silica sand in an electric arc and/or resistance furnace at temperatures of around 2000C (electricity typically represents 12.5 per cent of production costs at a scale of 5 000 tpa. The fused silica is crushed to market specifications.
Australian Silicon Ltd
New South Wales project
Portman Mining (with Thiess) and Iwatani Corporation of Japan (90:10) are evaluating a A$120 million silicon metal project near Lithgow in New South Wales. It would be located at Wallerawang, adjacent to power station. It aims to produce 30 000 tonnes of metal grade with a cash cost of US$1000 per tonne (metal grade valued at US$1400, chemical grade at US$1 800).
About 80 000 tonnes of quartz will be mined at Glenella about 30 km from Cowra with a minelife of 35 years.
Charcoal to be supplied from hardwood (not coal, noting Portman's interest in coal mining with Burton mine in Queensland) produced from south coast of NSW at Moruya.
45 Megawatts of power will be supplied at US$0.02 per megawatt. Power will then represent 22 per cent of operating costs.
Updates - Australian Silicon
March 2003. Suspended trading on stock exchange (shares last traded at A$0.07) responding in large part to successful campaign by environmentalists to deny access to timber waste for charcoal.
October 2001. Quaestus Ltd shareholders approved the acquisition of Portman Ltd's 90 per cent stake in the Lithgow silicon project in New South Wales. Under the terms of the sale agreement, Portman will receive 36.5 million shares in Quaestus valued at $7.3 million which will deliver it a 66 per cent stake in the company. It will be known as Australian Silicon Ltd - a Perth based company with Peter Anderton as MD.
In 1997 Doral, a subsidiary of Iwatani International Corporation of Japan acquired the Glenella quartz deposit near Cowra in New South Wales and carried out a preliminary feasibility study into the establishment of a silicon smelter. In 1998 Doral and Portman entered into a joint venture agreement to carry out a detailed feasibility study whereby Portman would contribute $1.0 million towards the cost of the study to earn a 50% interest in the Project. In May 1999, Portman increased its interest in the Joint Venture to 90% and has expended approximately $7.3 million on the Project to 30 June 2001.
The Australian Silicon Project is proposed to consist of the following:-
* The Glenella quartz mine situated approximately 200 kilometres west of Lithgow. The mine has a measured resource of 2,100,000 tonnes and is forecast to produce about 80,000 tonnes per annum of high quality quartz pebble that will be transported by road to Lithgow. The mine has sufficient reserves to sustain a proposed smelter for at least 20 years.
* A silicon smelter at Lithgow situated approximately 130 kilometres west of Sydney. The smelter technology will be provided by Mannesman Demag, an acknowledged technology supplier. The smelter will comprise of two submerged arc electric furnaces with a combined design capacity of 31,500 tonnes per annum and the associated raw material and product processing facilities.
* A carbon production plant at Moruya at the south coast of New South Wales will require 400,000 tonnes per annum of residual timber (stumps and branches) to produce 31,000 tonnes per annum of charcoal that will be transported to the silicon smelter and used as a carbon reductant in the smelter.
The total capital expenditure and working capital requirements of the Project are estimated to be approximately $165.5 million, of which a major portion is a turn key contract price for the silicon smelter, and the balance for the quartz mine and the carbon plant.
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