“Innovative Blast FreeMining Methods for

Aggregate Quarries "

Ramesh Bhatawdekar,

Edy Tonnizam Mohamad,

Firdaus Azlan

Department of Geoteknik and Transportation,

Faculty of Civil Engineering,

University Teknology Malaysia,

G.K.Pradhan

Department of Mining Engineering

AKS University, Satna, India中国砂石协会

Introduction

• Concrete – Per capita consumption 1 T

• Consumption of natural aggregates concrete

• Aggregates are commonly mined with blasting worldwide

• Blasting increases various hazards

• Study of geological factors necessary for optimizing blast

design as well as for breaking rock with new technology

• Physio mechanical properties affect selection of technology

• New Innovative Technologies under development for breaking

rock with minimum hazards 中国砂石协会

Environmental Hazards due to Blasting

• Type of hazard Possible Impact Common Causes

• Fly-rock Property damage, Geological conditions,

Serious injury, Over charge of explosives,

Loss of life Stemming length, back break

• Ground Vibration Annoyance to public, Exceeding max charge/ delay

Cracks in property

• Air Blast Annoyance to public, Use of detonating fuse

Glass pane breakage

• Fumes, dust Local hazard

• TECHNOLOGICAL DEVELOPMENT IN INITIATION SYSTEM

Ordinary detonators – Electric delay detonators- Sequential Blasting

Machine- Cord relays -Non electric detonators- Electronic detonators

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Technological Milestones in Mechanical Cutting

• YEAR

• 450 BC

• 1913

• 1920

• 1980s

• 1987

• 1990

• 1994

• 1999

• TECHNOLOGICAL EVENT

• Surface scratching by Paleolithic miners for stone implements

• Development of bucket wheel excavator

• Concept of continuous and mass mining systems

• Surface miners emerge as a clean mining system

• Hofmann, reported use of continuous surface miners as a

technology for opencast.

• Gujrat Ambuja Cement developed Wirgen 1900 Surface Miner

for trial basis

• Introduction of high wall system

• Surface miner introduced in Indian Coal Mines中国砂石协会

Types of Natural Aggregates

• India• Basalt

• Calcgranulite

• Charcnockite

• Chert

• Granite

• Greywacke

• Limestone

• Magnetite

• Muscovite

• Quartzite/ Quartz wacke / Greywacke

• Quartz/Quartz Mica Schist

• Sandstone

• Trap Rock

• Malaysia• Agglomeratic tuff

• Chert

• Glassy Acidic to Intermediate Volcanic

• Granite

• Geyseites

• Hornfels

• Impact rocks

• Intermediate Volcanics

• Metaquartzite

• Mylonized rocks

• Quartzite

• Rhyolite

• Sandstone

• Siliceous Shale

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Selection of Rock Excavation Process,Machines

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Evaluation of Rock Breaking Methods

for Rock Breaking Systems

• Determining rock strength – compressive and tensile strength

• Determining energy related indices- crushing energy factor

• Measurement of rock breaking parameters – cutting resistance, depth

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Rock Properties

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Prediction of specific energy required for cutting (Barendsen, 1970)

Barendsen, (1970)

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Determination of excavation possibilities(Atkinson, 1971)

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Pettifer–Fookes chartDiscontinuity Spacing Index Vs Point Load Index

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Overall Assessment of Excavability of Rock Mass

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Excavalibilty of Jointed Rock Mass using Geological Strength Index (GSI)

• ..

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Summary – Excavability of Jointed Rock Mass using GSI

• The Geological Strength Index (GSI) used to assess the ease of excavation

of rock masses :Figure A ( Is50 \3 Mpa ) and Figure B (Is50 C 3 Mpa)

• Blasting required GSI values are greater than 65 when Is50 C 3 MPa and

60 when Is50 \ 3 MPa, hence blasting is usually required in massive, blocky

and very blocky rock masses or when joints are tight.

• Successful ripping is generally achieved for rock masses with GSI values between 20 and 45

• In the transitional zone between the ripping and blasting areas of the GSI charts, excavation with hydraulic breakers is necessary.

• The proposed classification is applicable only for rock masses where discontinuities control the excavation, thus is should not be used for the assessment of excavation in heterogeneous rock masses

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Surface Miner

.

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Selection of Surface Miners

Geotechnical parameters

• Uniaxial Compressive Strength

(UCS)

• Tensile Strength

• Moisture Content

• Abrasivity

• Brittleness

• Stickiness

• Percentage of silica

Rock properties

• Schmidt hammer – for Rebound Test

• Scan line survey – to determine the discontinuity by carrying out this test at the cutting edge/face created by the surface miner,

• Laboratory investigations

• Point Load Strength Index (PLSI in MPa) using BEMEK tester. 中国砂石协会

Parameters Influencing Cuttability of Surface Miner

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UCS of Rock Vs Surface Miner

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Rippability based on Excavability Index

• The excavatability index depends upon mass strength number, rock

quality designation (RQD), joint set number of Q – system, relative

ground structure number, joint roughness number of Q – system,

and joint alteration number of Q – system (Kisten, 1982).

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Hydraulic Rock Breaker

• Various Manufacturers are

available for supplying Hydraulic

Rock Breakers mounting on Back

Hoe Excavators.

• Suitable application for breaking

boulders to avoid secondary

blasting

• Output 180 to 200 TPH

• Operating pressure 300 PSI

• Still need development to utilize

Hydraulic Rock Breaker as Primary

Breaking 中国砂石协会

Controlled Foam Injection Technology

• The method uses high-pressure foamto initiate, pressurize and propagatecontrolled fracturing in rock. The foamis injected to the bottom of a relativelyshallow pre-drilled hole in the rock tobe broken by means of a barrelincorporating a hole bottom sealingmet. The pressures required tofracture and excavate rock aresignificantly less than required inmethods based upon the use of smallexplosive.

• Air blast and fly rock are reduced andthus allowing application in urban andenvironment sensitive area

• .

• Controlled Foam Injection (CFI) method uses as high as 83 MPa (12,000 psi) pressure when breaking a hard granite. Breakage efficiencies of 0.06 m3 tof0.24 m3 per break observed during trials.

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Rock Breaking using Chemical Methods

• Expansive Mortar which can fracture rock or concrete with expansive force of 15,000 psi (1034 kg/cm2). Productivity of mechanical breakers is also increased by fracturing rock. Product can be used for pre-splitting rock in sensitive conditions. Expansive Mortar can be used in dry and watery conditions hole diameter upto 76 mm.

• Application : For boulders, depth of hole is 65 to 70% height of boulder.

• 10 times hole diameter is distance between holes and holes are drilled in square or diamond pattern.

• Presplitting Mortar is added to holes and after 6 hours , boulder or surface is cracked. 中国砂石协会

Rock Splitting Mortar

• Advantages• Eliminates noise, fly rock and vibration

potential caused by blasting or heavymechanical means

• Increases productivity of hydraulic rockbreaker

• Accelerates removal time once fracturingoccurs

• Works underwater in difficult conditions

• Minimizes risk in high exposure situations

• No license for storage of rock splittingmortar中国砂石协会

Plasma Technology for rock breaking

● A group of scientists at the Korea Instiute of Geology, Mining and Materials (Min et al.,1997) established the plasma blasting method for rock fragmentation.●

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Plasma Technology Process

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Conclusion

• Blasting has fly-rock, ground vibration, air-blast and fumes as hazards.

• In environmentally sensitive areas, various technologies are being tried for

more than 2 decades

• Aggregates .produced from granites, basalts, quartzite, chert, limestone, etc

• Study of compressive strength, tensile strength, geological strength Index

for excavation are necessary to decide type of excavation method

• Surface Miners, Hydraulic Rock Breaker, Rippers are suitable for certain

rock types with geological features (very blocky to disintegrated), for blast

free mining

• Hydraulic Rock Breaker is used mainly for boulder breaking. Further

development required for primary breaking.

• Rock splitting Mortar with Hydraulic Rock Breaker can give advantage of

rapid breaking of rock.

• Rock Splitting Mortar ,Foam Injection technology and Plasma Technology

are immerging technologies which need to be established for aggregate

quarry application

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Points for discussion Status of Blast Free Mining at China

• Whether proven technologies like Surface Miner or Hydraulic Rock Breaker are in use at China?

• Any other blast free technologies being used in China.

• Future scope of blast free technologies in China.中国砂石协会

.

• .

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References

• [1]. Atkinson, T.: Selection of Open Pit Excavating and Loading Equipment. Transaction Institute of Mining and Metallurgy – Section A, A101–A129 (1971)

• [2] Barendsen, P.: Tunneling with Machines Working on the Undercutting Principle. In: Goodman, J.A. (ed.) The Technology and Potential of Tunneling, Proceedings of South African Tunneling Conference, pp. 53–58 (July 1970)

• [3 ] Janus Res, K. Wladzietczyk, Ajoy K Ghose Book- Environment Friendly Techniques of Rock Breaking

• [4] Min, J. S., Chung, Y. W., Lee, H. J., & Lee, D. N. (1997). A study on the environmental and safety problems and their remediation around mining areas. Korea Institute of Geology, Mining and Materials (Vol. 32). Research Report KR-97 (C).

• [5] Pettifer GS, Fookes PG (1994) A revision of the graphical method for assessing the excavability of rock. Q J Eng Geol 27:145–164

• [6] Pradhan, G. K., Prakash, O., & Thote, N. R. (2014). Blast Free Mining in Indian Surface Coal Mines–Current Trend. In Mine Planning and Equipment Selection(pp. 335-357). Springer International Publishing

• [7] Swamy R. N. (1992) Book- Alkali Silica Reaction ,

• [8] Tsiambaos, G., & Saroglou, H. (2010). Excavatability assessment of rock masses using the Geological Strength Index (GSI). Bulletin of engineering geology and the environment, 69(1), 13-27.

• [8] Venkatesh, H. S., Bhatawdekar, R. M., Adhikari, G. R., & Theresraj, A. I. (1999). Assessment and Mitigation of Ground Vibrations and Fly rock at a Limestone Quarry. In Proceedings of the Annual Conference on Explosives and Blasting Technique (Vol. 2, pp. 145-152). International Society of Explosives Engineers.

• [9] Young, C. (1999). Controlled-foam injection for hard rock excavation. In Rock Mechanics for Industry, Proceedings of 37th US Rock Mechanics Symposium, Vail, Colorado (Vol. 1, pp. 115-122).

• [10] YOUNG, C., & GRAHAM, C. (1999). CONTROLLED FOAM INJECTION PROGRESS TOWARDS AUTOMATED HARD ROCK EXCAVATION. In Proceedings of the 5th International Symposium on. Mine Mechanization and Automation, Sudbury, Ontario (p. 39).

• [11] http://www.daighcompany.com/products.asp

• [12] https://www.youtube.com/watch?v=zzoatmX_Xh8

• [13] http://www.wirtgen.de/en/products/surface-miners/

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