Chief Executive Officer, R.K.Marbles Ltd.

Sr. Manager (Mines), R.K. Marbles Ltd.

 

There are huge marble deposits scattered through out India to be exploited for dimensional stone. Estimated reserves in India are about 1200 Million Tonnes and out of this about 90% are spread in different districts of Rajasthan state.

 

For economical exploitation of marble deposits systematic & scientific mining is the critical need of the time and so is the selection of proper equipment and technology.

 

Out of various steps in extraction of marble, drilling is a most important step. Different types of drill machines like LD4, Slim drill, Quarry Master, Heavy duty Mega drill and Wagon drill are playing important role for quarry front cutting. Slim drill is mainly used for drilling co-planner holes. Mega drill, a heavy duty machine, is used for drilling 175 mm dia. and higher size holes for blind cuts etc.

 

Apart from drilling machines following combination of equipment is necessary for achieving quarry front cuts and are used depending upon the requirement of a particular pit:

 

1.      Slim Drill – Diamond Wire Saw.

2.      Quarry Master - Diamond Wire Saw.

3.      Belt Saw - Diamond Wire Saw

4.      Blind Cut Machine - Diamond Wire Saw

 

 

 

It is also known as “Performatic Drilling Method”. In this method Quarry Master is used for making a back vertical or bottom horizontal cut. The cut is generally 5-6 meter wide and 7.5-8 meter in depth, which is a limiting factor. The quarry master drills holes of 115 mm dia. at a close spacing of 2.5 cm upto the desired depth. The parting left between holes is broken with the help of a specially fabricated button bit with side wings and giving percussive motion only with the same drill. In this way a clear slot of desired width and depth is achieved. From the other end two horizontal or vertical (as the case may be) holes of 115mm dia. upto the slot are drilled with the help of slim drill. These holes shall facilitate the diamond wire to pass through them for further cutting operation. Thereafter with the help of diamond wire saw, side cuts as well as bottom/ back cuts are achieved completing the Quarry front cut operation (Fig, 1-2)  

 

 

Technical Specifications of Quarry Master

 

Drill Machine Dimensions:

 

 

·             Suitable where quartz is present in marble

·             Less skilled worker can operate & maintain the machine.

·             Handling is easy.

·             Time consuming.

·             Dust & Noise Nuisance.

·             Costly marble is wasted in slot.

·             Not suitable in loose and crack strata.

·             Jamming of hammer and bit.

·             Quarry front (galli) cut possible only in two steps.

 

Due to the above mentioned disadvantages, the use of Quarry master in mechanized marble quarries is on decline.

The belt saw is a machine specially conceived for extraction of marble blocks from a marble quarry. The machine is essentially composed of different parts shown in fig. 3

 

 

 

 

The machine is made up of a frame, which supports motor block and an arm over which a diamond belt runs. The frame is set on rails, which it runs along the rails. The machine is electrically powered except for the movement of the arm carrying head, which is hydraulically powered. The motor block consists of three electric motors, one for the rotation movement of the diamond belt, second for the turning movement of the diamond belt– carrying arm and third for the traverse movement of the frame along the rails. The same frame also holds another two motors for accessory functions and the control box for the machine. The arm can rotate vertically 360° and can be positioned both vertically and horizontally as shown in fig. 4. The belt runs along the lower edge and forms a loop around the arm. A small wheel is mounted on the top of the arm to help the translatory motion of the belt; inside the arm are the channels, which distribute pressurized water to lubricate and remove fine particle from the belt. After achieving a horizontal or vertical (as the case may be) 38mm cut of 2.97 meter deep and desired width, two vertical or horizontal holes of 115mm dia. are drilled upto the cut by slim drill machine. Thereafter with the help of diamond wire saw side cuts as well as bottom/ back cuts are achieved completing the quarry front operation.

 

The belt is composed of a series of small metal cables covered in plastic and distributed with 3 cm long rectangular steel bars whose external surface is clad in diamonds. The diamonds are sintered with help of a cobalt and bronze binder. The belt has approximately 13 diamond bars per linear meter.

HORIZONTAL CUT

 

 

 

 

 

 

Advantages

·             High Productivity.

·             No theoretical limit to the length of cutting.

·             Absence of dust.

·             Vibrations relatively scarce.

·             Quality of blocks is better.

·             Optimal dimension for Gang saw cutting.

·             Higher yield of slabs.

 

 

Disadvantages

·             Availability of water

·             Limited depth of cut < 3M

·             High cost of equipment

·             High cutting cost

·             Handling is possible only be means of cranes/ excavators

·             A regular geometric quarry is required (plain surfaces)

 

 

This is a simple machanism composed of two 37mm x 75mm MS channels 10-12 meter long. For convenience of handling and requirement of varying depth these channels are made in pieces of 5 meter, 3.5 meter, and 1.6 meter length with fish plates welded at their upper end for achieving required length by joining them with nut bolts. The lowest channel has a base plate and a 150 mm dia. pulley with double row ball bearing encased in a polyurethene seal filled with grease. The upper portion has a pulley of 350 mm dia. as shown in fig. 5

 

These channels are lowered down into already drilled 175 mm dia. holes of required depth along with diamond wire passing over the lower and upper pulleys and finally connected to a diamond wire saw. These two vertical holes accommodating channels are connected with 115 mm dia. horizontal holes at the bottom for cleaning the slurry generated during cutting. When the diamond wire saw moves away with Diamond wire in the initial stage rotating and running, linearly cut the marble rock from top to bottom. In a latest development a pulley with stand is placed in the center of the cutting width over which this diamond wire passes to minimize the trust while cutting the corner edges of the cut. The height of blind cut channel is kept more than the height of the cut so as to compensate the parabolic cutting surface at the bottom and achieve a level surface. With this technology, we can save much time and cost in making a quarry front (galli) cut which in turn reflects in higher productivity. A comparison of quarry front (galli) cut by belt saw machine vis-a vis by blind cut machines is done in a table given below:

	Belt saw			Blind cut
	Period	Cutting Sq. ft.	Cost Rs.	Period	Cutting Sq. ft.	Cost Rs.
Month	Jan.02	2892.00	764000	April,02	6038	139000
	Feb.02	2580.00	684000	May,02	4832	115000
	March,02	1163.00	308000	June,02	7173	165000
Total		6635.00	17,56,000		18,043	4,19,000
Avg. cost (Rs./Sq. ft.)	264.66			23.22

 

 

 

·             High productivity values

·             No limitation of depth of the cut

·             Initial investment is very low

·             Low cost of Cutting/ Sq. ft.

·             Simple operation

·             Easy in handling

·             Save in time due to of higher rate of cutting.