BK-Granite(F)

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IMPACT OF FAVOURABLE AND DISATOROUS GEOLOGICAL STRUCTURES IN PRODUCTION AND SAFETY OF GRANITE QUARRY OPERATIONS:

B.KANISHKAN IMPACT OF FAVOURABLE AND DISATOROUS GEOLOGICAL STRUCTURES IN PRODUCTION AND SAFETY OF GRANITE QUARRY OPERATIONS

Focus:

Focus To discuss on various technical and environmental problems To establish a logical link between sound geological knowledge and successful exploitation To suggest optimum utilization of waste generated. To discuss on various technical and environmental problems To establish a logical link between sound geological knowledge and successful exploitation To suggest optimum utilization of waste generated. Focus

BACKGROUND INFORMATION :

BACKGROUND INFORMATION ODYSSEY OF GRANITE TRADE ROLE OF A GEOLOGIST IN DSG GEOLOGICAL FACTORS THAT CONTROL PRODUCTION Regional Geology Petrology Structure Sheet characterization

Regional Geology:

Regional Geology

Deposit Characterisation of DSG :

Deposit Characterisation of DSG Basic Criteria Marketing aspects Geological aspects

Marketing Aspects :

Marketing Aspects Fundamental aspect in determining the success of dimension stone quarry operation is its export demand. If the demand persists, the life of its operation prolongs and vice versa. Export market is based mainly on its pleasing colours, design, and aesthetic value besides capable of taking good polish. Buyer’s preference differs from country to country. Therefore,valuation of granite deposits should focus on export market demand besides on other technical considerations.

Buyers Preference in Kashmir White Past and Present:

Buyers Preference in Kashmir White Past and Present

Geological Aspects:

Geological Aspects Mainly include study of mineralogical and structural aspects of the granite sheet formation. Sheet rock should be more or less uniform exhibiting preferred design and colours besides less of inclusions. Major failures in granite quarry operations is due to the structural disconformity of the sheet rock to produce defect free gang saw size rough blocks (minimum size 240 x 120 x 100 cm). A critical study of the structural stability of the deposit is of paramount importance in determining the success of the quarry operation . Geological structures can be grouped as: Favourable Unfavourable & Disastrous structures

Favourable Geological Structures:

Favourable Geological Structures Facilitate easy recovery of blocks of desired export sizes with minimum usage of men, material and machinery forces. Presence of such favourable structures viz. sheet joints; vertical joints; steep dipping foliation planes; migmatitic structures etc. enhance the recovery percentage in quarry operation Value addition by way of production of big gang saw sized blocks.

Sheet Joints:

Sheet Joints Sheet joints at desired levels in a quarry, lessens the burden of bottom cutting and also minimise waste generation. Major advantages: To plan effectively the quarry operation/production schedule. Determine the third dimension (thickness) of the rough block, which is a vital factor in fixing the price Minimise the deployment of expensive quarry equipment for bottom cutting By inducing minimum force, the bottom cutting can be achieved The absence of sheet joint at times create more problem and also involves risk especially in a much valued black granite deposit, in achieving the bottom cutting Wire saw cutting minimises the risk.

Favourable Geological Structures:

Favourable Geological Structures

Favourable Geological Structures:

Favourable Geological Structures

Favourable Geological Structures:

Favourable Geological Structures

Vertical Joints:

Vertical Joints Presence of both vertical and sheet joints in a deposit is really a boon for speedy exploitation. Advantages are: Facilitate smooth splitting of rock. Minimum wastage High recovery and low cost of production.

Migmatitic Structures:

Migmatitic Structures Widely seen in migmatites and the major attraction to foreign buyers, when seen up with pleasing colours. Export price of rough blocks are decided on such cosmetic look. Important multi-coloured granite deposits possessing such cosmetic designs are the Paradiso deposit of Krishnagiri; Colombo Jubrano of Togamalai; Tamil Nadu; Pink-multi of Kanakapura, Karnataka; Kuppam green of AP etc., It is essential for export market that such wavy designs are less affected by natural defects, like criss-cross hair-line fractures, quartz and pegmatite veins besides, enclaves of black mica/amphhibolite patches which may spoil the look/beauty of the polished slabs.

Migmatitic Structures Tiger Skin:

Migmatitic Structures Tiger Skin

Steep Dipping Foliation Planes :

Steep Dipping Foliation Planes Natural weak planes help in smooth splitting of blocks. If the vertical splitting mechanism synchronises with the foliation plane of the rock, the advantages are: Avoids wrong cutting to spoil the beauty of the finished product viz. slabs/ tiles. Enhances the durability of the slab and tile. In the case of black galaxy deposit, Ongole, AP; the galaxy (bronzite) is exposed mainly along the foliation plane and hence rock splitting should be oriented along that plane only.

Unfavourable Geological Structures:

Unfavourable Geological Structures Unfavourable geological structures are: Close spaced vertical/oblique joints, minor faults, silickensides, hair line fractures; low dipping foliation planes etc. Presence have an adverse effect on quarrying and ultimately restrict the size of the blocks. Though harmful to export market, may allow some blocks of smaller dimension especially in high value Kunnam black granite deposit and black galaxy deposit, Ongole. Smaller blocks of jet black granite can be utilised for processing UK monuments besides accessory items for Japanese monuments.

Unfavourable Geological Structures:

Unfavourable Geological Structures

Close Spaced Joints:

Close Spaced Joints Presence of close spaced joints of both vertical and inclined restrict the size and shape of the boulders By critical study of joint pattern vis-à-vis the size, shape and weathering pattern of the boulders especially in a dyke rock, one can visualise the nature and quality of the sheet rock occurring beneath. Accuracy in such analysis will facilitate preparation of a feasibility report for exploitation of granite deposit. In certain cases, the close spaced vertical joints as seen in some black granite quarries of Chamrajnagar, Karnataka, persist deep into the sheet rock and hence the recovery of blocks are restricted to monument size(>0.25 CBM) blocks.

Close Spaced Joints:

Close Spaced Joints

Minor Faults:

Minor Faults Frequently intercepted in black granite dykes and exhibit a dextral and sinistral pattern along its ‘Run’ By carrying out strike mapping with a tape and compass the structural disposition of the dyke can be brought out. Surface expressions: Boulders of cobble (uneven) sizes. Odd shaped sheared boulders showing deep weathering Dextral and Sinstral shifts at closer intervals. Development of secondary features like hairline fractures, silickensides, quartz and pyrite specks; white moles of quartz and feldspar etc.,seen mainly along fault planes.

Low dipping Foliation Plane:

Low dipping Foliation Plane Recovery and the size of the blocks are reduced. Further, while processing for tiles and slabs, the material quarried from such low dipping formations generally yield a poor recovery besides a low durability strength. A suitable example is the Kerala-white(leptynite) occurrence of Quilon district, wherein the formation dips at 40-45 and it becomes difficult to split the blocks parallel to the foliation plane. A similar situation has been experienced in the Summer Sky multi-coloured granite prospect of Sankari area, Tamilnadu, wherein the formation dips at a very low angle(4-5 ) and hence the operations stopped due to poor recovery.

Kerala White Deposit:

Kerala White Deposit

Low dipping Foliation Plane:

Low dipping Foliation Plane

Low dipping Foliation Plane:

Low dipping Foliation Plane

Folds:

Folds Major fold structures are common in multi-coloured granite deposits. In such case, quarrying along limb portions may be safer than nosal portion, since the fracture cleavages restrict the recovery and size of the blocks.. Sira Grey granite occurrence in Tumkur district, Karnataka is a linear deposit and the fine grained grey granite band exhibits, warping and swerving along its length. Therefore, the quarries opened within such kink portions exhibit criss-cross veination of pegmatite and hence the quarry operations are to be suspended for low recovery.

Shear Cracks:

Shear Cracks Shear cracks are normally noticed within the structurally disturbed zones. Effects of minor shears in a granite deposit is manifested in the form of thin and linear nerve like fractures cross-cutting the formation which are harmful to quarry operations. Restrict both size and recovery of blocks.

Disastrous Geological Structures:

Disastrous Geological Structures Harmful in totality in granite operations. These structures are of regional phenomena like the lineament zone, major shear zone, suture zone, active fault zone etc. Granite deposits including the dykes emplaced earlier to the tectonic activity are badly affected. Such deposits are not suitable for exploitation and in certain cases, it is difficult even to retrieve blocks of cobble sizes.

Disastrous Geological Structures:

Disastrous Geological Structures

Sheared Dyke:

Sheared Dyke

Effect of Major Shearing in DSG Deposits:

Effect of Major Shearing in DSG Deposits

Environmental Problems:

Environmental Problems Environmental impact on mining and quarrying in general is an issue of major concern since it has direct bearing not only to the natural ecosystem but to the society. Most of the major mineral deposits either occur in forests or in revenue lands and once we start exploiting them, naturally we will be damaging the environment one way or rather. It is an accepted fact that for the development of the economy some percentage of environmental sacrifice being allowed under some considerations. However, stringent laws are in force to minimise such damages. Environmental concern in the case of granite quarrying is much more alarming since quarries are mostly located both in revenue and private lands and few cases in forest lands also. Most of the agriculture belts turned out to be the potential pockets for exploitation besides it causes much of societal problems since located near the villages. Problems are very many but the remedial measures as suggested can have some solace to minimise the environmental damages.

Environmental Problems in Quarrying DSG :

Environmental Problems in Quarrying DSG Land degradation Disposal of waste rock Air and noise pollutions

Land Degradation:

Land Degradation Though land degradation in mining of any mineral wealth is inevitable, it can be minimised in the case of quarrying DSG deposits by the following measures: Proper scientific assessment of the deposit prior to its exploitation. Stringent measures to backfill the abandoned quarries.

Scientific Assessment of Deposit Prior to its Exploitation:

Scientific Assessment of Deposit Prior to its Exploitation Average failure rate in DSG deposits is quite high besides yielding a low recovery rate. For example in the type area of Paradiso granite deposit in Krishnagiri belt, Tamilnadu, out of the 125 working quarries examined by GSI during the resource survey, only 25 quarries assessed to be more promising and productive and another 25 quarries categorised under average and the balance 75 quarries under failure category. Reasons for failures are : Failure to produce desired gang saw size blocks due to hair line fractures Non-uniformity in colour and texture of the material Quartz and pegmatite intrusions Irregular pattern of enclaves inclusions etc.,

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CASE STUDY Paradiso Granite Deposit,Krishnagiri, TamilNadu

Paradiso-Bed Rock Profile:

Paradiso-Bed Rock Profile

Scientific Assessment of Deposit Prior to its Exploitation:

Scientific Assessment of Deposit Prior to its Exploitation In view of the geological attributes as mentioned, failure rate in quarry operations turned out to quite high. As a result the quarries had to be abandoned abruptly causing much damage to the environment (land degradation) and huge accumulation of waste rocks. Most of the agricultural belt mainly mango yielding belt has been damaged in Krishnagiri area. Above environmental damage could have been avoided had the deposit been assessed scientifically prior to commencement of exploitation. Basic failure to understand the geometry of deposit is causing much environmental degradation besides on disposal of huge waste rocks.

Disposal of Waste Rocks:

Disposal of Waste Rocks Disposal of huge quantity of waste rocks in quarry belts is causing much of following environmental problems: Space crunch to locate and maintenance of spoil banks within the quarry belts. Sliding and creeping of boulders along the slopes of spoil banks sometimes causing accidents. Damage to vegetation especially dumped along the slopes of hills. Accumulation of waste in granite quarrying especially in black granite deposits is huge and unimaginable due to its poor recovery (5 to 10% in black granite and 25 to 30 % in multi- coloured granite deposits) and high failure rate.

Remedial Measures to Dispose of the Granite Wastes:

Remedial Measures to Dispose of the Granite Wastes Production of value added products from granite wastes like garden lamps and other artefacts Production of kerb and cobble stones for export market Utilised for laying local roads and construction materials especially multi-coloured material Erection of groynes along the vulnerable coastal erosion zones to resist against future attack of Tsunami.

Erection of Groynes/Rubble Mounted Sea Walls (RMS) in vulnerable Tsunami affected coastal stretches:

Erection of Groynes/Rubble Mounted Sea Walls (RMS) in vulnerable Tsunami affected coastal stretches Out of the 480 km coastal stretch lying between Nagapattinam and Kanyakumari fringing the east coast, only around 75 km aggregate length of villages is to be protected by the proposed Rubble Mounted Rubble Walls (RMS)/groynes, to resist against the damages of tsunami waves (Source GSI Survey report)

Stone budgeting Erection of Tsunami Rip-Raps/Groynes :

Stone budgeting Erection of Tsunami Rip-Raps/Groynes Estimated requirement of granite rubbles is around 10 million cu.m. Estimated availability of accumulated granite in quarry belts is around 30 million cu.m. Therefore considering the surplus quantity of granite waste available in the quarry belts, the proposal for its utilization for Tsunami protection structures can be easily achieved

Advantages:

Advantages Solves major environmental problem in quarry belts. Material readily available for the proposed Tsunami protection structures. Cost effective. Requirement for the coastal stretch between Cuddalore and Nagapattinam can be sourced from Tindivanam-Villupuram-Trichy sector and between Nagapattinam and Kanyakumari from Trichy-Pudukkottai-Madurai-Tirunelveli-Kanyakumari-Trivandrum sector to optimize the lead. Prevent further land degradation in out sourcing the material from new granite deposits.

Conclusion and Recommendations :

Conclusion and Recommendations Proper assessment of the geometry of each granite deposit ultimately determines its recovery, size and scope of the prospect. Our past experience in the trade has taught us a lesson that the success of the industry primarily depends on adopting the right techniques both in evaluation and its exploitation with latest technological advancements to fulfil the basic requirements of overseas buyers. Present trend in the industry is focused on High volume and Low margin business.

Conclusion and Recommendations:

Conclusion and Recommendations Any new material which was earlier rejected by the buyers is acceptable to-day, provided the price is competitive. Thus, by re-orientation of the granite resource survey and its exploitation methods to suit the global requirements, the industry is poised for a big growth in the years to come.

Conclusion and Recommendations:

Conclusion and Recommendations Suggestion to utilise the huge accumulated granite wastes in the quarry fronts for erection of groynes along the identified pockets of coastal stretch to protect against future attack of Tsunami has not only a relief to environmental problem but also has societal significance

Slide 57:

. THANK YOU

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