Introduction

Before 1977, India was one of the main sources of high grade kyanite with exports to most of the industrialised nations of the world. However, about this time the Indian Government, in an attempt to preserve indigenous resources for domestic use, imposed export restrictions. There is a huge reserve of low grade kyanite, containing 30-45% Al2O3, which awaits detailed exploration and beneficiation for making them useable in order to utilise resources and boost export possibilities. Beneficiation studies carried out on low grade kyanite ores at National Metallurgical Laboratory have shown that concentrate having 58-62% Al2O3, which is acceptable grade-I refractory raw material, could be produced by adopting suitable process technology.

Beneficiation studies carried out at NML with low grade kyanite ore, from eastern part of India, produced encouraging results. A simplified process flowsheet is given below:

ROM -> CRUSHING -> GRINDING -> DESLIMING -> (HYDROCYCLONE ) -> MAGNETIC SEPARATION -> FLOTATION -> DEWATERING -> CONCENTRATE

Details of Present/existing/Technology. Shortfall/Technological gaps in the existing technology

India is one of the leading producers of the kyanite in the world. The total recoverable reserve of kyanite in the country, as on 1.4.95., is placed at 2.8 million tonnes. Besides, conditional resources of 161 million tonnes of Kyanite are also established. High grade kyanite resources of the country are nearly depleted. Beneficiation of low grade Kyanite today is very relevant in view of the shortage of high grade kyanite, required for high alumina refractory making, and need for utilising low grade resources which are available in abundance. Few attempts have been made at NML and elsewhere to upgrade low grade kyanite ores to generate usable product. Available low grade kyanite resources are studied to be amenable to beneficiation. As there is need for high grade kyanite in domestic as well as international market, present technology has been developed.

Approach adopted in new technology to evade technological gap in the existing one

ROM ore is crushed and milled. Gangue materials are separated by desliming and magnetic separation (wherever necessary). Finally values are recovered by flotation. The process produced grade-I material having, in some cases, 97% kyanite, as well as 85-90% material as required.

Advantage

The world demand has changed from massive variety to beneficiated concentrates and synthetic mullite. Indigenous beneficiation technology being available, India's vast low grade kyanite resources could be converted to a foreign exchange earner basides meeting domestic need. At present most of the requirements of the western world for sillimanite group of materials are met by USA, South Africa and France. With the present liberalisation policy, beneficiated kyanite export may become feasible if a suitable technological process is adopted. It can be mentioned here that USA, number one exporter of kyanite, boosted its kyanite production mainly by the beneficiation of low grade ores and utilising the resultant fines. Further, countries like Germany, UK, Japan, Italy, Belgium, Netherlands being solely dependent on imports of kyanite - the prospect of exporting kyanite has become very high.

Applications

Mineral, Metals & Materials

Used in manufacture of refractory bricks and in monolithic applications such as castables, mouldables and ramming and gunning mixes.

Status of Development

The process has been developed on a 25 tpd basis

Ecological/Environmental Impact

Planned tailing disposal and dust catching arrangement should be provided.

Technology Transfer Assistance Offered

(a) Process Know-How,
(b) Details of the Equipment,
(c) Plant lay-out &
(d) Quality assurance methods.
Assistance in setting up a plant on separate terms

Contact for more information:

Director
National Metallurgical Laboratory
Jamshedpur-831 007, India
Tel: (0)657-2271715, 2270092
Fax:(0)657-2270527
Email: director@nmlindia.org