The modern method of coal mining in underground mines is the longwall system, which has been adopted all over the world because of its high output, high productivity, better safety and improved recovery achievable by this method

When longwall technology was finding root in the country in the early 80s ,SCCL availed the opportunity and reconstructed two of its on-going mines and introduced longwall face equipment in the years 1983 and 1985

These longwall units ,apart from working creditably, have provided an opportunity for SCCL engineers to study the equipment and support parameters vis-à-vis the geo-mining conditions prevailing in the SCCL mines. The specifications of future longwall face equipment are being drawn based on this study and experience

It is proposed to replace the single motor (1x375 KW) drive sheares with twin motor (2x375 KW) drive shearers to enable the shearer to cut the face with desired ease for better machine utilization. Similarly the 4 x 360 tone chock shield supports are found to be inadequate to support the massive sand stone roofs and it is proposed to go in for higher support ranges of the order of about 750 tones. The study and recommendations of central mining research station, Dhanbad, also conforms to the proposed increase in the range of supports

A large number of the new mining areas projected in the perspective plan (like Chinnur,Bhoopalalpalli-Mulug,Srirampur) have gradients of seams varying between 1 and 2.5 to 1 in 3.5. longwall technology has not ,so far ,been attempted in the country at such steep gradients and SCCL, probably out of necessity, has had to take lead in this aspect

The technology for exploiting steep seams even of the order 1 in 1,by longwall method ,is available in countries like FRG and UK and with proper tie-ups in the initial stages, SCCL expects to implement longwall technology successfully in steep seams

Further, SCCL has formulated three projects with barrierless longwall mining which are in the process of being sanctioned by the government of India .it is proposed to implement this technology ,initially with the technical assistance from soviet experts. This technology will further increase the recovery from coal deposits by about 20 percent.

Extraction of seams thicker than four meters has always been a technical problem to the mining industry in the country as also to SCCL , which has an eight-to-ten meter thick coal seam all over its coalfields. Conventional board and pillar development and depillaring in two sections has widely been executed over the decades in the mines, but with poor recovery and risk to safety.

During the year 1980-81,SCCL looked for specialized technologies being used abroad for mechanized extraction of thick seams to obtain larger outputs with better recovery and safety from thick seams .a feasibility report was obtained from charbonnages de France (CdF) in 1984 for extracting eight-to-ten meter thick seams in GDK-10 incline by “blasting gallery technique”. This methods is currently on trail, under A to Z concepts with the technical assistance of CdF, and the results so far are encouraging . though the trail is undertaken in a virgin portion of the thick seam, the technology can be extended with little modifications for extracting thick seam working developed either in single or double section

SCCL has nearly 300 million tones of coal reserves standing on pillars. Such a huge inventory of standing coal pillrs has resulted due to

i) The upper seams became vendible and their development was taken up subsequently, locking up developed pillars in the bottom seams and

ii) Thick seams developed in the single section and final extraction delayed science there is no proper technology available to extract the complete thickness

The SCCL realized the necessity for a mechanized technology for rapid liquidation of coal pillars , to keep to the sequence of extraction of coal seams and to get larger outputs, this led SCCL to look at the experience of Australia, which gets a major portion of its underground coal production by mechanized bord and pillar method. The SCCL is, shortly hopeful of experimenting with the Australia technology of Wongawillie method continuous miners for liquidation of pillars in one of its mines with the collaboration of Australians.

The SCCL is, however ,aware that the application of continuous miners is again limited to areas of flat gradients of around 1 in 6 , and the search for a suitable method for mechanized liquidation of pillars standing on gradients steeper than 1 in 6 is to go on