|home | about us | articles | psu links | directory | publications | initiatives | feedback | contact us ||
Journey from Beach Sands to Nuclear Fuel
||By S. Sivasubramanian, CMD, Indian Rare Earths Ltd.|
The beach sand mineral industry in India originated in the early part of 20th century when monazite, a radio-active golden yellow heavy mineral basically containing rare earths and thorium in phosphate form was discovered in the coirs of coconut brought from Kerala to the European countries. Those days this mineral was being highly sought after for the potential uses of thorium contained in it for producing bright light out of gas burners when used as mantles. Of course at that point of time neither radio-activity nor the potential of thorium as future use in nuclear power programme was known. Foreign companies owned by the British started exploiting this mineral from the western coast of Indian peninsula and exported it to Europe for manufacturing gas mantles by using thorium extracted out of this mineral.
After India gained its independence from the British rule, Atomic Energy Commission was established in 1948 and export of monazite or any such compound bearing thorium and uranium was banned by the Govt. of India considering their potential for future use in nuclear energy. Dr. Homi Jehangir Bhabha who is the founder of India’s nuclear power programme has well conceived the role of thorium in view of its indigenously vast available resources compared to that of uranium by laying down the road map for developing 3 stage atomic power programme. On 18th August, 1950, Indian Rare Earths Ltd. was incorporated under the Companies Act with its registered Head office at Mumbai and soon after the work on setting up a plant at Aluva, Kerala, started to process monazite based on the process know-how developed by a French company. The plant was commissioned in 1952 and since then has been contributing significantly to the country’s nuclear power programme.
Beach sand minerals are a suit of 7 naturally occurring substances i.e. ilmenite, rutile, leucoxene, zircon, monazite, sillimanite and garnet. These minerals occur along the beaches in the coastal regions as placer deposits. Indian sub-continent has 6000 km long coast line out of which the Atomic Minerals Directorate for Exploration & Research, Hyderabad (AMDER) has explored about 2550 km and currently beach sand mining operations are limited to maximum 100 km. Based on survey carried out by AMDER as of September 2005 the inventory of national mineral resources is reported to be 461 million tonnes ilmenite, 27 million tonnes rutile, 10 million tonnes monazite, 28 million tonnes zircon, 151 million tonnes garnet and 190 million tonnes sillimanite. The above resource of beach sand minerals in India accounts for more than 25% that of the world.
Ilmenite is the most abundantly occurring mineral comprising approximately 53% of the total national resources of beach sand minerals. Sillimanite and garnet, occur in less percentages at 22% and 17% respectively. Zircon and rutile each share approximately 3% followed by leucoxene at 2% and monazite at 1% of the total assemblage of such minerals. However, the relative percentage of such minerals may vary depending on their mineralogy and geographical considerations of the site of their occurrence.
In addition to the above mentioned unit at Aluva, Kerala, which is known as Rare Earths Division, Indian Rare Earths Ltd. has three more mineral production units viz. Minerals Division, Chavara in Kerala, Minerals Division, Manavalakurichi (MK) in Tamil Nadu and the Orissa Sands Complex (OSCOM) at Chatrapur in Orissa. The company has total installed capacity to produce about 5 lakh ton of ilmenite, 0.3 lakh ton of zircon, 0.2 lakh ton of rutile, 0.2 lakh ton of sillimanite, 0.1 lakh ton of garnet and 0.05 lakh ton of monazite per annum. The MK plant and Chavara plant were taken over by the company from their original British owners during 1966 to 1971 and OSCOM plant was commissioned in 1987.
Global production of ilmenite is reported to be 10 million tonnes followed by zircon at about 1.3 million tonne. Annual production of rutile, garnet and sillimanite are around 4 lakh tonne each and annual production of leucoxene is reported to be around 2 lakh tonne
Titanium pigment and titanium sponge which are the value added products of the ilmenite, rutile and leucoxene account for approximately 87% of the global market estimated at US dollars 10.5 billion. The estimate of market for value added products of zircon which is mostly consumed after grinding it to micron size is much lower at about US dollars 1.5 billion. The estimated market value of other two minerals i.e. garnet and sillimanite is marginal at US dollars 0.03 billion each. Currently monazite is not processed in the world and traded in a very limited manner due to its radio-active nature.
India’s share is about 7% of global ilmenite production followed by 4% for rutile and 1.5% for zircon. However, India contributes in large measure to the global production of garnet and sillimanite estimated at more than 50% for the former followed by around 5.5% for the latter. India consumes about 30% of the ilmenite produced in house along with entire domestic production of zircon, rutile and sillimanite.
Ilmenite, leucoxene and rutile are the titaniferrous minerals and contribute to the feed stock of the global titanium industry. Ilmenite containing titanium dioxide (TiO2) in the range 35% to 65% alone accounts for 90% of the industries’ requirement. Rutile contains TiO2 in the range 93-95% followed by leucoxene where TiO2 content varies over a wide range of 75-92%. Other than TiO2 these ores contain iron in large measure along with minor impurities such as alumina, silica, radio-active substances, oxide of vanadium, chromium, niobium, calcium, magnesium, phosphorous, sulphur etc.
The chemical composition of an ore has important bearing on its acceptability by the user industries who process them for manufacturing either titanium slag or synthetic rutile or use them for direct conversion into pigment. The level of minor impurities mentioned above may seriously affect the market value of the ore in addition to its TiO2 content. About 94% of the titanium feed stock is consumed for manufacturing titanium dioxide pigment and the balance goes into production of titanium metal, welding electrode coatings, titanium chemicals etc.
Ilmenite is converted to intermediate value added products such as titanium slag or synthetic rutile accounting for approx. 42% and 18% respectively of its consumption. Balance 40% of ilmenite is used directly for production of pigment. Rutile and leucoxene having higher TiO2 content are consumed directly by manufacturers of pigment, sponge/metal and welding electrodes etc.
In general the site of production of ultimate value added products i.e. titanium pigment and titanium sponge/metal are nearer to their place of consumption shifted far away from their mines. Overall about 2/3rd of total ilmenite produced in the world are consumed for intermediate/ultimate value addition with tie-ups and the remaining 1/3rd only is available for free trading.
South Africa and Canada along with Norway manufacture titanium slag out of ilmenite whereas Australia contributes to maximum production of synthetic rutile with marginal contribution coming from India and Malaysia for this slag or intermediate value added product. Norway consumes almost all of its low-grade ilmenite produced from rock source by converting it to TiO2 pigment. India along with Australia, Vietnam, Srilanka etc. provide for bulk of the tradable ilmenite in the world. The pigment and titanium metal manufacturing industries being located in the developed region of the world i.e. USA, Europe, Japan and erstwhile USSR, the cost involved in transportation by way of ocean freight has significant impact on the profitability of producers of the feed stock.
Titanium pigment manufactured both in anatase and rutile forms find applications in coating, paper, rubber and plastics, pharmaceuticals etc. As a premium product owing to its superior pigment properties its consumption is associated with life style appliances and high value end users who are influenced by the overall economic growth scenario of the region of its utilisation. During the past decade, the average global growth in demand of this product has been around 2.5% with relatively higher demand growth at 6-8% registered in the Asia-Pacific region mostly driven by increased consumption in China and India.
The process of manufacturing TiO2 pigment and titanium sponge are highly capital intensive and their state of the art production technologies are closely guarded secrets by these players. The cost economics of manufacturing is also sensitive to cost of available energy such as electrical power, coal and furnace oil including availability of other vital process inputs i.e. petroleum coke, sulphuric acid, hydrochloric acid etc. at competitive rates.
Titanium dioxide pigment is produced through chloride process or sulphate process. While chloride process that uses higher TiO2 containing feed stock could limit environmental problems, the issues associated with handling of large quantities of acidic effluents and problems of utilising substantial quantities of ferrous sulphate generated as a by-product in the sulphate route processing pose challenges in adopting this process though it is easy to adopt and economics of production are generally not sensitive to the scale of manufacturing pigments.
The slag production though solves the problem of waste by-product by converting iron in the ilmenite to pig iron, the process is highly energy intensive and the production cost is extremely sensitive to the cost of available electrical power. Large-scale furnace capacity also favours the economies of production cost.
Economic viability of synthetic rutile production is dependent on the availability of solid reductant i.e. coal of desired grade or petroleum coke etc. at competitive rates or on availability of chlorine/hydro chloric acid at the production site depending on the type of process involved i.e. lurgi becher or benelite cyclic process respectively. Though synthetic rutile having higher than 95% TiO2 is highly preferred by the titanium sponge leading to higher capacity utilisation of the processing
Both titanium dioxide pigment as well as the titanium sponge are unique products with no substitutes though their high prices lead to fall in their usage by the down stream industries who opt for cheaper products having inferior properties. Innovations and technology up gradation by the end user community also put significant pressure on price of titanium pigment forcing its producers to absorb the escalation in cost of inputs and raw materials.
The pattern of usage of titanium pigment and sponge by the consuming industries has undergone changes during the last decade. Paper industries are increasingly opting to replace this costly product by cheaper bentonite clay while boom in aero space sector has triggered demand for titanium sponge during the last 3 years after a prolonged recessionary phase of a decade when the industry was forced to limit its production level to 50% of its installed capacity.
Securing supply chain both for its process inputs and raw materials as well as ensuring control over the down stream distribution of its finished products for defending the desired profit margin in the environment of technology upgradation and product substitution are the major challenges faced by the industry players.
Unlike titanium bearing minerals which have alternate place of occurrence in rocks away from the coastal belt, zircon is industrially winned from placer deposits as a co mineral of titanium bearing ores. Chemically known as zirconium silicate, the zircon has minimum 64% zirconium oxide (ZrO2) content with balance being mostly silica. It may be associated with minor impurities such as iron oxide, titanium dioxide, alumina etc., which significantly influence its use by various market sectors and price.
About 90% of the zircon is consumed by industry segment such as ceramics, foundries and refractories without any chemical processing or change except grinding to various sizes (one micron through 45 micron) to suit the requirement of user industries. The remaining 10% is converted to zirconia, zirconium chemicals and metals for a variety of speciality uses such as abrasive, refractory, inorganic ceramic colour, structural ceramics, bio-ceramics, high temperature thermal barrier coatings, artificial gem stones, fuel cells, sensors, magneto hydrodynamic electrodes, structural of cores of nuclear power reactors, catalytic applications, electronic filters, transducers, resonators etc.
Australia and South Africa along with USA contribute to about 90% of world zircon production. Majority of the grinding facilities to convert zircon to zirflor and opacifier are located in Europe, Japan, USA and China i.e. nearer to their place of consumption. USA, China and Europe are large importers of zircon produced in South Africa and Australia. Hence, the effect of ocean freight variation and exchange rate fluctuations affecting the conversion of currencies i.e. US dollar, Euro and Australian dollar have significant impact of prices of zircon products.
The ceramic industries consume 52% of the total zircon followed by refractory and foundry sectors each of which account for 15% of the total consumption. Glass and zirconium chemicals consume each 8% of that of the industry sectors leaving remaining 2% for other users.
Processing of zircon to zirconia, zirconium chemicals and zirconium metals require chemicals such as caustic soda, sulphuric acid, petroleum coke, chlorine/hydrochloric acid and electrical power. Depending on the choice of processing route i.e. electro-thermal or chemical, the production cost is sensitive to the cost of available electrical energy or other process inputs. The production economy is comparatively less sensitive to its scale.
The product is difficult to substitute for its use as ceramic, foundry and refractory due to its unique properties i.e. to act as an opacifier in the ceramic glaze system, low-thermal conductivity coupled with stability at high temperature and low bio-toxicity respectively.
During the last decade there has been no significant change in the pattern of zircon consumption. The growth in demand for zircon in the Asia pacific region far surpasses the global average mainly due to boost in construction industries in China and India.
The uniqueness of the product associated with its source of production as well as poor substitutability by the end users translates into wild swing in its prices as can be seen from the record of past 3 decades. It has reached its peak twice falling sharply to the bottom by as much as 300% and currently on the 3rd peak after registering a hike of more than 200% from its price only 5 years back. High price leads to replacement of zircon by other products having equivalent properties such as magnesia alumina spinel substituting zircon in steel industry and vitrified tiles replacing glazed tiles etc. Zircon being a co-product of titaniferrous industry, its production is associated with that of titaniferrous minerals totally distinct from its demand by user industries.
The industry is consolidated at the supply end as well as in the processing side as about 4 companies control 40% of the market in the opacifier segment and four other players contribute to more than 70% of the production in the mineral sector.
Naturally occurring garnet in the placer deposits of coastal belts is of iron alumina silica type known as almandite having the highest hardness of 7.5 in the mho scale among the family of 5 other varieties of garnet. The mineral is a solid solution of one or more varieties of these garnet types in almandite. The mineral product having minimum 98% garnet should not contain more than 25 tpm of chloride and level of quartz should preferably be less than 0.5%.
The product fetches a premium when graded in close range of particle size distribution for its use in abrasive, blast cleaning or water jet cutting. The abrasive blast cleaning application attaches a premium to the coarser range such as higher than -20 + 40 mesh size and the water jet cutting application prefers finer grade of material such as -80+110 mesh size.
Garnet grinded to micron range particles such as 5 micron or less find application in the polishing of glass, furniture, TV/computer display tube faceplate and IC chips. Micronised garnet for polishing application is a high value product.
Coarse garnets also find its use as a filter media in the tri-media filter used for water filtration. In this system, the tiny-grained garnet forms the first layer at the bottom of the filter on which medium grained silica sand is used followed by top layer of coarse hard coal
During the last decade the consumption pattern of garnet has under gone changes with enhanced application in the field of water jet cutting. Currently blast media application account for 35% of consumption followed by 30% for water jet cutting, 15% for filtration and 10% each on account of powder abrasive and other uses. The garnet production has gone up at an annual compounded rate of 10% during the last 10 years and the price has remained constant due to supply pressure.
The aluminium silicate is the chemical formula of sillimanite. Andalusite and kyanite are the other isomorphs of this mineral. The mineral contains minimum 58% of alumina, the remaining being mostly silica. Titanium oxide, iron and alkalinity originating from shale materials are not desirable in the product as they affect the refractoriness of the finished products.
90% of the product goes for refractory application with remaining 10% being consumed by other applications. Steel industry is the major user of sillimanite refractories and the remaining is consumed by chemicals, glass, non-ferrous metals and other materials.
This product, like garnet is highly vulnerable to substitutions from other competing materials and hence is highly price elastic.
Indian sillimanite compares favourably with calcined kyanite and andalusite as it has very low loss in ignition and low iron. Sillimanite converts to mullite when heated above 1650oC resulting in economies in cost of production of refractory bricks. This can be used along with zircon or zirconia to produce zircon mullite bricks used in glass melting furnaces.
During the last decade, sillimanite from placer deposits have replaced the lump sillimanite produced from rocks in the Meghalay region. Increased demand for glass and steel in construction industries keeping in pace with the general economic growth of the country has kept the demand for sillimanite growing at an average rate of 6% year.
The chemical composition of the ore is thorium, rare earths phosphate. Thorium being a radio-active material, the processing of monazite is subject to strict provisions of radiation control measures. The ore has around 9% thorium oxide, 55% rare earth oxide and 22% phosphate as P2O5. Titanium dioxide, zirconium oxide, quartz etc. are not desirable as impurities as they affect the over all economics of processing of the ore.
In India, monazite provides the rare earths also known as lanthanides which are obtained during processing of the ore by caustic soda route. Phosphate value is realised as trisodium phosphate and thorium is recovered as thorium hydroxide/oxalate. Part of the thorium is processed to make thorium nitrate used by gas mantle industries and the surplus thorium is stored in engineered silos for future use in nuclear power reactors.
Measures to handle radio-active material during processing of monazite coupled with the cost of long term storage of thorium severely affects the cost economics of producing rare earths from monazite. The competitive pricing of rare earth compounds manufactured in China from non-radioactive sources such as bastanaesite and ion exchange clays have completely taken over the Indian market and monazite processing has been suspended for the last three years.
During the last decade the usage pattern of rare earths have undergone radical change owing to developments in technology front and application of individual rare earth element in magnets, battery etc.
IREL uses state of the art technology in mining and mineral processing. The rich experience and professional expertise of the people, who are one among the best in the industry and strict compliance to quality standards, have enabled IREL to remain as the leading supplier of heavy minerals, to the nation and abroad.
|All articles in this website are copyrighted and any infringement will be dealt with strict legal action.|
| RNI No.
@ Shilpa Bichitra | All Rights
Reserved | Designed by: DigiPalette
Gouri Shankar Das