subject: Impregnated Grade Coal Tar Pitch - CSIR - NPL Technology [print this page] Impregnated Grade Coal Tar Pitch - CSIR - NPL Technology
Impregnated Grade Coal Tar Pitch
Recently I visited CSIR technofest 2010 showcased by Council of Scientific & Industrial Research, New Delhi, at India International Trade Fair in New Delhi, the Capital of India. In this technofest, I have seen a technology "Impregnated Grade Coal Tar Pitch" which was developed by NPL (National Physical Laboratory), New Delhi under the aegis of CSIR, New Delhi, India.
The commercially-available coal tars or tar pitches invariably contain the QI-particles (5-15%), which make them unsuitable for the impregnation purposes.
The impregnating-grade coal tar pitch is a special type of coal tar pitch, which has a low content (0-3 %) of quinoline insolubles (QI), besides having lower values of softening point (SP), toluene insolubles (TI), coking yield and specific gravity (SG), compared to those of the binder-grade coal tar pitch.
It is used in large quantities to densify graphite electrodes, employed in steel and chemical industry. Besides this, it is also used in the development of advanced carbon products like high performance carbon fibre, needle coke, high-density high-strength graphite and carbon-carbon composites which has many potential applications.
The conventional methods involving filtration, solvent extraction and centrifugation for the reduction or total removal of these QI-particles from these materials are cumbersome and expensive. The present process of the producing the impregnating-grade coal tar pitch is very novel and involves the treatment of the commercial coal tar or coal tar pitch with special inexpensive / industrial solvents.
The treatment results in the separation of the pitch-solvent mixture into two components - one major, which contains almost no QI, and the other minor, which is rich in QI. The minor component is reused in the process and the major component is heat-treated to recover the solvent and obtain the impregnating pitch.
The process involves state of art technology to remove QI particles from the coal tar pitch without filtration or centrifugation techniques. This is extensively used for the densification of graphite electrodes & anodes, C-C composites and other carbon products.
It is used an excellent precursor for advance carbon products like pitch based carbon fibres, high density high strength isotropic graphite, Supreme Quality needle coke, Matrix of C-C composites.
The characteristics of the pitch produced at NPL by the present process are as follows:-
Softening point 80-100*C Quinoline insolubles (QI) 0.0-3.0 % Toluene insolubles 16-24 % Coking value 42-46 % Specific gravity 1.26-1.28 Ash content 0.05 % (Max.). It is indigenous technology and economical and 2 Kg batch level development of QI free impregnating pitch.
This technology has already been transferred to M/s Konark Tar Products Pvt Ltd, Durgapur, India for 200 Metric Tons per month capacity.
The below links may be useful for more details and information
