SHAFT SINKING

Rajiv Gandhi College Of Engineering, Research & Technology

PRESENTED BY : SUNIL D. WASADE

Guided ByProf. B.K. KHADE

H.O.D. Dr. M.D. Uttarwar

Mining Engineering 2015-2016

CONTENTS Introduction

U/G & O/C Comparison Deepening And Widening Of Shaft Special Methods Of Shaft Sinking

1. Wood/Steel Piling2. Open Caisson3. Cementation Process4. Freezing Process

Advanced Techniques In Shaft Sinking1. VSM – Vertical Shaft Sinking Machine2. Shaft Boring System3. Shaft Boring

ConclusionsReference

INTRODUCTION

In India, “MINING” industry is the backbone of India’s economy and energy. After agriculture mining is the second most important industry on which India’s economy is depend. Which helps in growth of any country in every aspects, because all existing industries are depend on mining. There is none of the industry which will replace to mining industry. Mining remains the most important player in the Indian industry, as well as Indian economy, Mining industry plays an important role in the development of nation.

For underground mining working access should be very precious and reliable. There are many other access but most reliable option one access to excavate deep seated mineral body, that term is called as SHAFT. There is no other access existing which can replace shaft. So we will have to go through shaft. And for better shaft reliability we have to sink in better ways, that’s why SHINKING is very important. But there are many things would be considered. Then we can make better shaft.

Speedy and economical shaft sinking operation depends upon not only on actual sinking speeds but to a great extent also on the planning of the number and the size of the shaft of the hoisting equipment. the shaft sinking with permanent winding equipment offers some advantages due to the fact that in this case the transition from shaft sinking to tunneling requires less time and that in case the transition from shaft sinking to tunneling requires less time and that it is possible to dispense with the expenditures on the installation and dismantling of temporary equipment.

Mechanical excavation methods are a step change in excavation performance and labour safety compared to drill and blast operations. In hard rock conditions, road headers cannot be used effectively, so disc cutting is the first 

For excavation of declines, tunnel boring machines (TBM) can be used in many cases. These provide, in certain rock conditions, considerably higher production rates compared to drill and blast excavation. Vertical shaft sinking machine (VSM) that allows excavating shallow shafts in soil a medium soft rock.

OPENCAST AND UNDERGROUND PRODUCTION COMPARISION

DEEPENING AND WIDENING OF SHAFT

DEEPENING OF

EXISTAING SHAFAT

DEEPENING OF EXISTAING SHAFAT

• A regular coal winding shaft 6.0 m in diameter has to be deepened to touch the bottom seam 100 m below without affecting normal winding operations.

Major equipment:• 1. Electric winding engines 2• 2. Hoisting sheaves 2• 3. Sinking buckets 3• 4. Single tub cage 1

 

DEEPENING OF EXISTAING SHAFAT

• 5. Tubs• 6. Jack hammer 6• 7. Pneumatic picks 4• 8. Pneumatic face pumps 2• 9. Electric pump• 10. Platform with folding doors for shaft top• 11. Shuttering for concreting• 12. Pipes, cables, ropes etc.

Deepening operations• Small shaft “A” is sunk near the coal winding pit on the side, away from

main haulage level. Head room is made for installation of winding sheaves of the hoist “E”. The depth should be enough to reach beyond the sump of old shaft, cross the safety rock plug “p” and allow sufficient head room for the installation of the sheaves of second hoist is driven.

• Level road way “L” to the position on shaft deepening. The place is widened and heightened for installation of winding engine “H” its sheaves and other equipment. Additional hoists are installed for carrying the suspended sinking equipment. 

• The shaft center is marked accurately by correlation through the shaft “A”. The perimeter to be excavated is marked on the rock surface.

• After deepening the shaft to some depths the platform with folding doors is installed at its mouth.

• Sinking proceeds in the normal manner. The rock from sinking buckets is dumped into mine tubs and hauled up through shaft A. The debris can be packed into underground galleries or hoisted to surface through the main winding shaft for disposal.

• On completion of sinking plug P is removed in sections.

 WIDENING A SHAFT • WIDENING A SHAFT USED FOR COAL WINDING: In

this case entirely different procedure must be adopted, one of the essential items of equipment being a strong cylindrical steel shield which fits inside the old shaft and does not interfere with the travel of the cages.

• PRELIMINARY WORKSufficient ground at the surface must first be excavated behind the old shaft walling down to the depth of say 30 m to enable a concrete wall 1m thick and 6m internal diameter to be erected all around the shaft. This wall should be founded on steel girders and provided with pockets with receives other girders for the support of existing pit-top frame, receiving guides etc.

• The next step is to erect a strong platform on girders at the depth of 3.6m and to widen the shaft to this depth, the debris being raise to the crab engine and kibble. The platform then removed and re-erected at the depth of 6m., the shaft being widened to this depth in similar way. The widened shaft should be supported temporarily by steel ring and backing deals, the first ring being hung from the girders at the base of the concrete walling is built up and the platform removed all together.

• All this preliminary work is necessary to enable the protecting shield walling platform to be installed in the shaft.

SPECIAL METHODS OF SHAFT SINKING

1. Wood/Steel Piling2. Open Caisson3. Cementation Process4. Freezing Process

SHAFT SINKING METHODS

a) Wood/Steel Piling

This method is known as simply PILLING or SHEET PILLING and is suited sinking through loose deposit of sand , mud,or alluvium near the surface upto a depth of 20 m. Interlocking steel pile, 6m to 10m long,are used and they are practically water-tight. Additional length may be available by welding or riveting2 or 3 lengths of pile.The surface, the piles are setup to from a ring and then they are hammered down in rotation, each member being driven a few meter at a time by adirect acting state piling hammer.As the pile descent in the lose ground, the latter,enclosed by the piles is excavated and cleared up, but it should be remembered that the bottom ends of the piles are kept sufficiently ahead of the excavation to prevent.Inrush of water are loose sand. When the excavation reaches strong rock, permanent lining is constructed and the sinking then proceeds in the manner describe for normal condition. 

a) Wood/Steel Piling

b) Open Caisson

In this method the shaft is started by digging shallow excavation and placing a cutting shoe on the bottom of the pit. The ground inside and just under the shoe is excavated and the lining is built up as theshoe sinks.

c) Cementation Process

Cavities and fissures are filled with quick-setting cement under high pressure then allowed to set. Cement pumps are designed for pressure as high as 6kgf to 300kgf.

This method is use in sudamdih and monidoh collieries.

d) Freezing Process

This method was first used in 1883. The wet round is artificially frozen

and then blasted and excavated as though it were solid rock. From 20 to

50 holes are drilled on the circumference of a circle. Circulating pipes are

placed in the holes and a calcium or magnesium chloride solution is

pumped through the pipes to freeze the ground.

ADVANCED TECHNIQUES IN SHAFT SINKING

RECENT/NEW METHODS OF SHAFT SINKING

There are different methods of shaft sinking/construction. Actually three

possible methods allowing a shaft to me sunk through highly weathered

over burden on the basis of Excavation and Wall support.

These are;

1. VSM – Vertical Shaft sinking Machine

2. SHAFT BORING SYSTEM

3. SHAFT BORING

VSM – Vertical Shaft sinking Machine

Shaft installation in difficult ground conditions – especially under ground water – requires special equipment.

Till today, with the help of several Vertical Shaft Boring Machines (VSM) dozens of shafts have been sunken in a variety of ground conditions.

They have a drill diameter of 5 to 10 meters and built shafts with a maximum depth of 65 meters.

VSM Technique is an application for Offshore Mining Purposes.

COMPONENTS SHAFT SINKING

MACHINE Shaft Sinking Machine consists of two main components

1.shaft boring machine2.the lowering units

The shaft boring machine is lowered into the launch shaft structure and attached firmly to the shaft with its three machine arms.

A rotating cutting drum equipped with chisel tools is attached to a telescopic boom.

This road header excavates and breaks the soil at the base of the shaft.

ADVANTAGES All operational processes are controlled and monitored from the surface. In addition to the separation plant, lowering units and recovery winches, the jobsite equipment includes a control container and power supply units.

All information available about the excavation is collected and visualized in the control container.

There, the operator has a full overview of the situation at hand and can respond accordingly at all times. After completing excavation or when changing excavation tools, the shaft boring machine is retrieved using the recovery winches. The advantages of the modular design of the overall system become particularly apparent in inner-city projects.

The equipment can be arranged as needed. For example, the separation plant can be installed in a street next to the jobsite if there is not enough space for it next to the shaft.

SHAFT BORING SYSTEM

The SBS is a development for the mechanized excavation of deep vertical blind shafts in hard rock conditions.

The semi full-face sequential excavation process is based on the use of a rotating cutting wheel excavating the full shaft diameter in a two stage process for one complete stroke.

The excavation process is divided into two steps:

trench excavation to a depth of one stroke with the cutting wheel rotating around its horizontal axis and being pushed downward in the shaft direction.

excavation of the entire bench (face) area by slewing the rotating cutting wheel 180° around the shaft vertical axis.

The SBS machinery consists of three major areas of equipment and

operation which are (starting from the bottom):

excavation chamber with cutting wheel, cutting wheel drive assembly, mechanical machine support structure, shotcrete and probe drilling equipment(Figure (1))

adjustable front support with slew bearing/drive assembly cutting wheel support and dust shield (Figure (2))

regular rock support area for rock bolts (Figure (3))

SBS mainframe with gripper carrier, gripper system and thrust cylinders (Figure (4))

rear alignment system (secondary gripper)

muck handling system (Figure 3(5)).

ADVANTAGES

High sinking rates.

High level of safety.

Integrated system for excavation, mucking and rock support.

Fully accessible bench.

Dedicated drill rigs for probing and pre-excavation grouting.

Semi-partial face excavation system with industry standard disc cutters.

SHAFT BORING

CONVENTIONAL PILOT DRILLING 

A tri-cone pilot bit is normally used varying from 9 inches (229mm) to 15 inches (381mm). The 15 inches (381mm) bit is normally used on long holes with a 12 7/8 inches (327mm) integral drill steel string with a 10 1/8-inch DI 42 tool joints. During drilling a fluid is pumped through the center of the drill string to the cutting face, where the rock cuttings are flushed and raised from the bottom of the hole through the annulus around the drill string to the collar of the hole. The drilling fluid is settled in a closed loop via a series of settling dams so that the drilling water can be re-used. See figure.  

CONVENTIONAL UP-REAMING OF PILOT HOLES: 

On completion of pilot drilling and at such time that the pilot hole breaks through into the lower excavation, a reaming head is fitted to the end of the drillstring. The size of the reaming heads range between 1, 2 meters and 6, 1 meters in diameter. The head is rotated by the machine and is pulled back against the rock face at the same time. Tungsten Carbide insert cutters are fitted to the head and these cut grooves in the rock in a rotary crushing mode. The ‘kerfs’ of rock in between the grooves ‘spall’ out and rock failure occurs in a tensile mode. The rock cuttings fall to the bottom of the hole where it is mucked out by a mechanical loader.

It is a safe, efficient and cost-effective method of making holes through different geological formations with the use of powerful machines, high strength drill string and reliable heads. The maximum loading capacity of the drill string limits the diameter as well as the length of the shaft. The loading is dynamic and only approximately calculable because tensile, torsional and bending stresses are overlapping. See figure. 

DOWN BORING WITH A PRE-DRILLED PILOT HOLE

In this case an oversize pilot hole is drilled. The cutting head is installed at the top of the pilot hole and drilling takes place in the downward mode. Rock cuttings are flushed down the oversize pilot hole to the bottom of the hole where it is removed. In the case of smaller holes, the machine provides cutter thrust and in the case of large diameter shafts the cutter head is weighted through the addition of steel collars. The down boring method is not used often as the risk of blocking the pilot hole and creating mud rushes at the bottom of the hole is too high. See figure.  

CONCLUSIONSIn day to day life, demands of mineral is increasing and for fulfillment of this we would extracted more minerals by increasing production and productivity of Indian mines working. The production of opencast mining is greater than underground mines but shallow depth reserves are being depleted, for what mineral have to extracted from underground by underground method. . But most of the mineral reserves are situated at great depth. For minerals extraction from underground drives access through shaft. And to drives shaft, sinking is most important aspect. So we have to adopt best sinking methods so that cost of sinking will be reduce and sinking work will be done at faster rate to achieve the targeted production. 

For better sinking methods we studied the various Shaft Sinking methods. After studying, found that, the advanced mechanical excavations systems can have significant advantages over conventional drill and blast methods for sinking of shafts in many different aspects. Advanced mechanical excavation systems allow for a significantly enhanced level of productivity and safety due to the high degree of mechanization and industrialization. Due to high production performance.

After studying case studies of two mines i.e Mansar and Balaghat mine in India where the shaft sinking was carried out recently by conventional shaft sinking methods techniques for the purpose of shaft sinking . The shaft of Mansar and Balaghat mines have made by Conventional Shaft sinking method but if this shaft would have been sunk with the advanced technologies like VSM and Shaft borer the production rate would have been raised to 30 % (Marks, 2002) with the sophisticated usage of manpower, increasing safety and reducing cost of capital on shaft sinking with less time required for sinking same length of shaft. 

Most reliable we can call that the advance sinking methods eliminates the usage of tedious method of Drilling and Blasting which is most critical to accidents with respect to safetyin mines. This mechanized method can also be applied for widening and deepening of existing shafts.

But there are some natural and technical problems, of using advanced techniques in India, regarding with natural and technical condition in India such as geology, ground condition, required capital cost, operating cost, environment, suitability of techniques with Indian mining atmosphere, lack of knowledge about techniques, lack of worker’s experience, other training arrangement.

So we will have to make several modification in technique’s construction and its working parameters according to suitability of techniques with Indian mining working and geological aspects. So that, it will work as better as possible and as per mentioned above, it will help to enhance production, productivity and safety measures of Indian mining industry. Really it will help to achieve India’s mineral target production.

In this thesis an attempt has been made to study the advanced shaft sinking techniques which are not practiced in Indian condition but in future those may be practiced in our condition and it will help to improve the production, productivity and safety measures. By application of the advanced techniques India can achieve their goals in production and economy.

REFERENCE 1. Dinesh Baliga, B-mechanised Shaft Sinking – JI. Of Mine, Metal

And Fuels And Special Number 1972.2. Chatterjee, S K Et Al- The Development Of Base Metal Mine –

Techniques Employed At Zawar Mines – Ji. Of Mine, Metal And Fuels And Special Number 1972.

3. Karwande, V L And Paranjpe D V – Mechanised Shaft Sinking At Singareni Collieries Ltd – Indian Mining And Engg. Journal, Special Number 1968.

4. Nath P D – Sinking Through Running Sand - Indian Mining And Engg. Journal, Special Number 1968.

5. Heinrich R. Gierke, Dulmen – Design Of Shaft ,Shaft Sinking – Symposium In Ranchi, Coal Expansion In India, 21-23 November 1983.

6. Walter Von Der Linden –N Shaft Sinking In Theory And Actual Performance - Ji. Of Mine, Metal And Fuels And Special Number 1962.

7. Mankovsky G I – Development Of Shaft Sinking Techniques In The Ussr - Ji. Of Mine, Metal And Fuels And Special Number 1962.

8. Horizon Mining By C.H. Fritzsche And E.L.J. Potts.9. Mining By B.Boky.10. Principles And Practices Of Modern Coal Mining By R.D. Singh.