ALTERNATIVE VERTICAL TRANSPORT ALTERNATIVE VERTICAL TRANSPORT FROM UNDERGROUND MINE BY DSI FROM UNDERGROUND MINE BY DSI

SNAKE HIGH ANGLE CONVEYORSNAKE HIGH ANGLE CONVEYOR(6(6THTH ASIAN MINING CONGRESS) ASIAN MINING CONGRESS)

(23(23RDRD TO 27 TO 27THTH FEBRUARY, KOLKATA) FEBRUARY, KOLKATA)

BY S.K.BAGBY S.K.BAG

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In 1979 the Bureau of Mines, United States Department of the Interior, funded a major study entitled“High Angle Conveyor Study.

The purpose: (1) To advance the state-of-the-art in high angle conveying.(2) To develop high angle conveying systems that would reduce the haulage costs in open pit mines. 

The study was awarded to a prominent U.S. engineering company.  Joseph A. Dos Santos - Project Engineer was assigned to the Study.

The two volumes “High Angle Conveyor Study” report, published in 1981, included the Dos Santos theory and various sandwich belt conveying methods.  Drawing from the success of the Loop Belt, Dos Santos Sandwich Belt systems included its best features and offered versatile profiles that could follow any high-angle path.

The Snake-Sandwich High-Angle Conveyor was cited as the preferred method and it was submitted for patent in 1981. 

The Sandwich Belt High-Angle conveyor research and development was published more concisely in the 1982 landmark article “Evolution of Sandwich Belt High-Angle Conveyors” by Dos Santos and Frizzell.

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High Angle Conveyor Study by Bureau of Mines, US.

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HIGH ANGLE CONVEYOR (HAC) is sandwich belt employs two ordinary rubber belts which sandwich the conveyed material.

Additional force on the belt provides hugging pressure to the conveyed material in order to develop sufficient friction at the material-to-belt and material-to-material interface.

This prevent sliding back of material.

The wide use of longwall systems in the 1980s required upgrade or replacement of existing conveyor lines to keep up with production.

In deep coalmines this had resulted in choking at the main haulage shaft where existing skip hoists could not meet the increased production.

This created great opportunities for high angle conveyors in the 1990s.

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What is High Angle Conveyor?

GENERAL ARRANGEMENT GENERAL ARRANGEMENT OF DSI SNAKE HIGH ANGLE OF DSI SNAKE HIGH ANGLE CONVEYORCONVEYOR

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SANDWICH BELT PRINCIPLE

SANDWICH BELT PRINCIPLE

PHOTOGRAPHS OF VARIOUS PHOTOGRAPHS OF VARIOUS SECTIONS OF DSI SNAKE HIGH SECTIONS OF DSI SNAKE HIGH

ANGLE CONVEYORANGLE CONVEYOR

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LOADING FROM UNDERGROUND

CONVEYOR ON TO HAC AT PIT-BOTTOM

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PIT BOTTOM

JOINING OF TOP BELT WITH BOTTOM AT LOADING POINT

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MOVING OF BELTS AFTER JOINTING

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VERTICAL STRUCTURE OF

HAC

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SANDWICH OF TWO BELTS BETWEEN TOP & BOTTOM IDLERS

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ORE SANDWICHED

BETWEEN TOP & BOTTOM BELT

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ARRANGEMENT OF IDLERS WITH SNAKE FRAMES

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INTERMEDIATE SNAKE FRAMES

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RETURN BELT OF TOP CONVEYOR AT

DISCHARGE POINT

RETURN BELT OF TOP CONVEYOR AT

LOADING POINT

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DISCHARGE OF MATERIAL FROM

BOTTOM BELT AT DISCHRGE POINT

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WHAT WILL BE THE MAXIMUM LUMP SIZE FOR HIGH ANGLE CONVEYOR

Studies in 1990 developed single and multi-flight systems as alternates to the traditional skip hoist systems.

These proved to easily handle the large throughput rates continuously through a mere conveyor to conveyor transfer chute precluding the large terminal storage and feeding systems that were required for the skip hoist batch haulage systems.

The economics were overwhelmingly in favor of the continuous haulage systems with Sandwich Belt high angle conveyors along the vertical shafts from underground.

Next slide shows two variations of continuous vertical haulage from underground, Scheme-A and Scheme-B. The original basis for these schemes was an underground nickel/copper mine with a net vertical lift to surface of 1381 m.

DSI SNAKE HIGH ANGLE CONVEYOR HAULAGE FROM UNDERGROUND MINE THROUGH VERTICAL SHAFT

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Scheme A - Main shaft of 7 meters finished diameter is able to accommodate the haulage system as well as all mine equipment access. The continuous vertical haulage system occupies half of the main shaft while the travel path of the 1.8 m x 4.9 m mine equipment cage occupies the other half.

Scheme B - Independent shafts are of 3.7 m finished diameter as this accommodates the haulage system as well as a 1.1 m x 1.7 m service cage.

Hoists/Elevators – Boreholes each equipped with rack & pinion type cages of approximately 1380 kg capacity. No auxiliary cage in main shaft. Main cage shall stop at mini-stations approximately 60 m apart.

SCHEME A SCHEME B

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GA OF HIGH ANGLE CONVEYOR THROUGH VERTICAL SHAFT

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~4 M

3.8 M

3.8 m diameter

1.8 m

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SUPPORT GIRDER FOR HIGH ANGE CONVEYOR IN SHAFT

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AUTOCAD DRAWING

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The HAC is a proven method for conveying materials vertically from tunneling operations to the surface.

DISCHARGE END OF HAC AT SURFACE

~4.0 M

INTERMEDIATE SECTION OF HAC

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SPRING LOADED IDLERS

INDUSTRIAL ELEVATOR (RACK & PINION TYPE) SERVICE CAGE

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Industrial elevators feature a rack and pinion drive for safe, reliable operation. Elevators are designed for safety. The pinion, which is driven by an electric motor mounted on top of the car, mates with the tower rack allowing the car to travel up or down on command. An electric multiple disc brake on the motor is used to stop travel. A loss of power automatically sets the brake.

In the event of a power failure, the car can be safely lowered to the nearest landing.

SKIP SYSTEM

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BOTTOM DISCHARGE SKIP

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SCHEMATIC ARRANGEMENT OF SKIP SYSTEM

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~25 M

~30 M

SCHEMATIC ARRANGEMENT FOR KOEPE WINDING SYSTEM

TOWER MOUNTED KOEPE WINDING DRUM

TOWER MOUNTED KOEPE WINDER

SKIP

~30 M

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SKIP LOADING AT PIT BOTTOM SKIP UNLOADING ARRANGEMENT AT PIT TOP

MEASURINGPOCKETS

SHAFT EQUIPMENT:

•The head frame•The winding rope sheaves•The winding ropes•The detaching hook & bell, safety clutches, cage/skip suspension•The guides•The kep gear – not required for Koepe system•The cages or skip•The heap stead or pit bank equipment•The pit bottom equipment•The winding engine, steam or electric•The signaling equipment•The over wind and speed-control equipment

DESIGN REQUIREMENT FOR HEADFRAME FOR SKIP

REQUIREMENT OF HEIGHT FOR HEAD GEAR FOR CAGE

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Dimension Method of windingCage Skip

A. Height of heap steadHeight of coal hopperB. Height of cageHeight of skipC. Suspension, chains, detaching hookD. Adjusting links & capelsE. Over wind distanceF. Clearance between “bell” & head sheaves

ft.20 – 30

-12 – 18

-7 – 95 – 6

5710 - 15

ft.-

20 – 30-

20 – 3066

5710 - 15

Total height of head frame

111 to 135 119 to 144

TYPICAL DIMENSIONS FOR HEIGHT OF HEADFRAME

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ARRANGEMENT OF ROPE GUIDES FOR CAGE

7.5 M DIA

ROLLER-GUIDE ASSEMBLY WITH FIXED GUIDES FOR SKIP

COMPARATIVE CASE STUDY BETWEEN SKIP & HAC SYSTEM

A nickel/copper mine located in North America.

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• Depth of mine – 1433 m

• Material bulk density – 2.0 t/cu.m

• Material size – 178 mm

• Production rate – 9072 t/day

• Production schedule - 8 hrs/shift; 20 shifts/week; 50 weeks/year

Based on system availability, utilization and experience, the skip hoist system was sized for 549 t/h, while the HAC system was sized for 636 t/h. The shaft diameter for skip (inside concrete lining) – 7.0 m

The shaft diameter for HAC system(inside concrete lining) – 5.0m

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BROAD PARAMETERS OF MINE

COMPARATIVE CASE STUDY BETWEEN SKIP & HIGH ANGLE CONVEYOR

The total drive power for skip hoist system was 4,476 kW, whereas the total drive power for HAC system was 3,580 kW.

HACs were 48 inches wide, belt speed 500 ft/min. Each HAC system covered 582 ft lift. Total lift for HAC system was 4,350 ft.

The capital outlay for Skip Hoist system was just over $50 million, whereas capital outlay for HAC system was around $41 million. The savings for HAC system was $9 million.

Annual operating and maintenance costs for skip hoist system was $1,963,000 /year and for HAC hoist system was $1,728,000 /year. Savings on operating & maintenance cost for High Angle Conveyor system was $235,000 /year.

Capital/construction & excavation cost summary in US $ has been given in the next slide.

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COMPARATIVE CASE STUDY BETWEEN SKIP & HIGH ANGLE CONVEYOR

Skip system HAC systemPreparatory workShaft Collar 937,000 400,000Set up sinking hoist 952,000 820,000Set up auxiliary hoist 207,000 n/aSinking hoist building 197,000 167,000Auxiliary hoist building 140,000 n/aPermanent conc. headframe 2,542,000 1,779,000Collar house 419,000 293,000A. Total preparatory work 5,394,000 3,459,000ExcavationsSink shaft Boreholes 25,334,000 13,580,000Station excavations 1,684,000 2,887,000Loading point excavation 144,000 n/aB. Total excavations 27,162,000 16,467,000Construction & InstallationLoading pocket construction 369,000 n/aStation construction 375,000 375,000Hoist rope & commission 553,000 276,000Shaft electrical - install 145,000 217,000

CAPITAL/CONSTRUCTION/EXCAVATION COST SUMMARY (IN‘$’)

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CAPITAL/CONSTRUCTION/EXCAVATION COST SUMMARY (IN ‘$’) (Contd..)

Skip hoist - install 528,000 n/aHACs – install, start-up n/a 2,865,000Cage hoist - install 526,000 526,000Tear down temporary equip. 66,000 66,000C. Total Construction & Installation 2,562,000 4,325,000Capital equipmentSubstation - Mine 2,395,000 2,395,000Friction & skip hoist 6,505,000 n/aHACs n/a 7,705,000Friction cage hoist 2,522,000 2,522,000Auxiliary hoist 933,000 n/aLoading pocket equipment 272,000 n/aSkips 290,000 n/aCage & counterweight 345,000 345,000Shaft electrics 2,205,000 3,960,000Alivator equipment for borehole cages n/a 630,000Total capital equipment 15,467,000 17,557,000GRAND TOTAL $50,585,000 $41,808,000Note: Costs include the material haulage system & also the equipment hoist & cage, the auxiliary hoist & cage and all associated excavations.

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KEY DIFFERENCES BETWEEN SKIP & HIGH ANGLE CONVEYOR SYSTEMPARAMETERS SKIP SYSTEM HIGH ANGLE CONVEYOR (HAC)

SHAFT DIAMETER 7.5 M

3.8 M(There will be ample empty space in the shaft, even after accomodating

HAC)

CAPACITY 500 -1000 TPH (CAPACITY SHALL BE REDUCED WITH SHAFT DEPTH)

4000 TPH & ABOVE (CAPACITY SHALL NOT CHANGE WITH SHAFT DEPTH)

HEIGHT REQUIRED AT SURFACE ~30 M 4 M

ADDITIONAL DEPTH AT PIT BOTTOM ~25 M NIL

DRIVE POWER DEPENDS UPON SKIP CAPACIITY & SHAFT DEPTH 20% LESS THAN SKIP SYSTEM

CAPITAL COST DEPENDS ON SHAFT DEPTH & CAPACITY LESS THAN SKIP SYSTEM

OPERATING COST -DO- LESS THAN SKIP SYSTEMMULTI LEVEL OPERATION NOT POSSIBLE POSSIBLE

DIRECT INTEGRATION WITH UNDERGROUND & SURFACE CONVEYOR

SYSTEM

NOT POSSIBLE POSSIBLE

REFERENCE PROJECTSDSI HIGH ANGLE CONVEYOR FROM

UNDERGROUND MINE

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J. A. DOS SANTOSJ. A. DOS SANTOSSandwich Belt High-Angle ConveyorsSandwich Belt High-Angle Conveyors

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J. A. DOS SANTOSJ. A. DOS SANTOSSandwich Belt High-Angle ConveyorsSandwich Belt High-Angle Conveyors

J. A. DOS SANTOSJ. A. DOS SANTOSSandwich Belt High-Angle ConveyorsSandwich Belt High-Angle Conveyors

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HAC IN VERTICAL SHAFT (DIA – 3.5)

HAC IN OPEN PIT

INTEGRATED HAC SYSTEM FROM UNDEGROUND TO SURFACE & COMPARISON WITH VERTICAL TRANSPORT WITH SKIP SYSTEM

ADDITIONALDEPTH OF29 M. AT PITBOTTOM

ADDITIONALHEIGHT OF30 M. AT SURFACE

SKIP SYSTEM

SHAFT DIA ~ 7.5 M

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VERTICAL HAC FROM U/G

HAC FROM OPEN PIT TO SURFACE

CONNECTING CONVEYOR

CONCEPT OF LINKAGE OF HIGH ANGLE CONVEYOR IN OPENCAST WITH VERTICAL TRANSPORT FROM UNDERGROUND (CHROMITE MINE)

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REFERENCE PROJECTSFOR

HIGH ANGLE CONVEYORS

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1. Receives material directly from underground conveyor and discharges directly on to surface conveyor.2. Material flow is continuous, the high angle conveyor can operate at modest speed while taking up very little space in the shaft. 3.66 m diameter shaft is enough to accommodate a high angle conveyor and service elevator.3.Single flight of 300 m is possible with standard fabric. Much higher single run lifts are possible with steel cord or aramid fiber belts. 4. A multi-flight high angle conveyor system has no depth limit as additional flights can be added. 5.The use of all conventional conveyor components permits high conveying speeds. Available belts and hardware up to 3000 mm wide make capacities greater than 4000 t/h. 4. High Angle Conveyor system suffers no loss of capacity with increasing shaft depth.5. High Angle Conveyor system exhibits high availability and very low maintenance costs.6. The economic advantage of continuous haulage with High Angle Conveyors increases dramatically with increased volumetric rate.7. Belts are easily cleaned and quickly repaired8. Spillage free operation7. Permits multi-level operation if ore is delivered to various High Angle Conveyor flights.

ADVANTAGES OF DSI SNAKE HIGH ANGLE CONVEYOR SYSTEM OVER SKIP FOR VERTICAL TRANSPORT

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HAC®s have found wide use in the marketplace. The system has proven to be very versatile with widely varying applications. Furthermore, HACs have proven their suitability for applications from underground mines to surface. By applying HAC in the shaft the production from underground mines can be easily increased.This will make a bright and exciting future for underground mines.

In India, huge good quality coal is available at a depth beyond 400 m. Ministry of Coal as well as Coal India Ltd have always mentioned to switch over to underground mining for coal. Hence, authorities may look at how “HAC” can be applied to raise coal from underground. Since, the required shaft diameter for HAC is around 4 m, hence Coal India Ltd can take-up R&D project for HAC to try in an existing ventilation shaft, which shall save sinking cost & shall not interrupt production from mine.

CONCLUSION

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ACKNOWLEDGEMENT

I GRATEFULLY ACKNOWLEDGE THE HELP, ACTIVE & PROMPT CO-OPERATION FROM M/S DSI SNAKE INTERNATIONAL, USA & THEIR INDIAN ASSOCIATE M/S BEVCON WAYORS PVT. LTD, HYDERABAD FOR PROVIDING THE RESOURCE MATERIALS ON DSI SNAKE HIGH ANGLE CONVEYOR, I.E INFORMATION, DATA, PHOTOGRAPHS, VIDEO, REFERENCE LIST ETC. USED IN THIS PRESENTATION.

WITHOUT THEIR HELP & SUPPORT, IT WOULD NOT HAVE BEEN POSSIBLE TO PREPARE THIS PRESENTATION.

THANK YOUTHANK YOU

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