LONGWALL TECHNOLOGY

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।

t 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

LONGWALL TECHNOLOGY IN STEEP SEAMS

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

LONGWALL WITH BARRIERLESS MINING

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.

THICK SEAM WORKING

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

RAPID LIDUIDATION OF COAL PILLARS

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