quarrying fernado daniel

QUARRY EXPLOITATION OF ORNAMENTAL STONES

THE PORTUGUESE EXPERIENCE

Instituto Geológico e MineiroMINISTÉRIO DA ECONOMIA

Portugal as some experience in the ornamental stones exploitationand in equipment production connected with this sector

The main production is centred in Granites, Marbles andSedimentary Limestone that are mined the first in the centre and north and the second in centre and south of Portugal.

We have yet some quarries of shales using the old technology – garrafão (big bottle)- but with very little production.

The development of the quarries industry is now dependent ofthe application and the coming in force of the new law publishedlast October.


One of the main alterations in this law is the newQuarry Plan that includes:

Geological surface mapping

Quarry exploitation plan

Environmental and landscape incidences, proposed solutions and control systems

Landfill plan

Closure plan and the landscape integration


This improvement in the law comes from the urgency to

modernise the old quarries with the integration of the

environmental questions and safety and environmental controls

and prevent, for the new quarries, the safety and environmental

incidences.

Looking at the ornamental stones types and exploiting methodswe will divide in two main sections:

Marbles and sedimentary limestone

Granites and similar rocks

Granites &Similars

Marbles & Sedim. Limes.

AREAS OF ORNAMENTAL STONES


MARBLES AND SEDIMENTARY LIMESTONE OPPEN PIT

The Marble area is the most important industry in the ornamentalstones field and was studied with the propose of reserves calculation and the possibility of underground mining.

In the biggest area of marbles occurrence the State Mining Servicemade a exhaustive study with the finality of preserving the resources and to give the necessary information for the development of underground exploitation.

This study can have a big influence in the development of the marble quarries

We know that the marble as yet good conditions at about 400 meters below surface

The methods used nowadays are the cut with the diamond wire and the transport of the blocks and waste rock by a ramp with dumpers or LHD machines. The vertical haulage is falling out of use because it is slower and more dangerous.


GEOLOGICAL MAP OF MARBLES AREA

The steel-wire and sand is not anymore in use because thevery poor performance and the danger connected with the length of the wire and the lack of signalling devices.

The cutting system with diamond-wire is used since we have a free face to facilitate the movement of the rock.


The evolution of the exploitation connected with the haulagesystem produced one change in the methodology to access the lower levels using the cut in ramp in such a way that it is opened the free face and the access for equipment.

ACCESS TO EXPLOITING AREA

MARBLE QUAARY

The evolution of the exploitation connected with the haulagesystem produced one change in the methodology to access the lower levels using the cut in ramp in such a way that it is opened the free face and the access for equipment.


AREA OF THE RAMP

ACCESS DRILING MACHINEdiameter 120mm

Drilling cutting system

ACCESS AREA WITH RAMP

DETEAILS OF PERFORATION

1

43

5 6

2

7

89

1011

Development Scheme

A

A

B

B

The development of is made using the diamond wire to cut the blocks with approximately 4 x 2 x 2 meters

The sequence and direction of the exploitation is commanded by the existence of fractures and fissures on the massif

The traditional system of access in the opening of the ramp is the side of the quarry that has poor conditions of profitabilityNow it can be made everywhere.

MARBLES - UNDERGROUND EXPLOITATION

The Environmental problems and the new laws about land occupation are moving the owners or the marble quarries to underground exploitation.

We have only a quarry that is using this methodology butsome studies are been conducted in the direction of this change.

The experience is not yet enough to present many problems connected with this activity.

In any case the cost of underground exploitation got with this experience is sufficiently attractive to suppose that it will cover the environmental costs that with the evolution of the exigencies of the surrounding communities will be each time bigger.

UNDERG. EXPLO. OPPENING

INSIDE VIEW

UNDERGROUND EXPLOITATION

GRANITE AND SIMILAR ROCKS EXPLOITATION

Portugal has a good experience in granites production andthe exploiters try to use the best technologies in this field.

We can find quarries of all dimensions using more or less up-to-date methods.

The normal method is the use of drilling to cut the blocks afterthe opening of the free face using the explosive and placed in anon usable area.

DIAMOND WIRE CUT

HORINTAL PERFORATION

CUT MACHINE

HORIZONTAL AND VERTICAL PERFORATIONFOR THE FREE FACE OPENING

The normal way is to open the free face using the diamond wire and separate the big blocks with explosive.

PERFORATION FOR CUTING THE BLOCK

CUTING SYSTEM

VIEW OF THE QUARRY

The operation is conducted:

Drill one vertical hole with 100/120 mm diameter in such a waythat they contact in the bottomIntroduce the diamond wire and cut all surface

At about 8 meters in the length of the front, repeat the operation

Drill horizontal and vertical holes with a pitch of about 20 cm

Blast with detonating cord and ANFO

Cut the big block into pre-commercial blocks with gunpowder

Tilt the blocks with a machine

Gunpowder cut

The transport of the blocks is made with dumpers to the store near the cutting equipment to prepare the faces and to put themat commercial dimensions

SHAPING MACHINE

The granite quarries operating in this conditions can reach one efficiency of about 15% in total blocks but less than 10% in good quality blocks.

The waste rock is used for civil work purposes.

EXPLOSIVE PREPARATION

For the control of the power of the explosion nowadays thecharges are pre-prepared and adapted to the effect they want.

The size of the charges of ANFO and its spacing is calculatedusing the the parameters connected with the rock type and volume of the main bloc.

Although it is not evident all workers use cotton clothes to avoid possible accidents with the explosives.

Safety and Environment in ornamental quarries

The bigger problem in quarries operation is:- the control of environment problems- the current of the public opinion - the opinion of environment authorities about it’s aggressiveness and of the unsafeness.

What can we do to change this opinion?Really the operation can be dangerous, insecure and aggressive to

the environment.

But, we have solutions and we must apply them.

The operators must

Study the geological conditions in such a manner that permits to provethe existence of the useful rock, the mineral reserves, the main structure and the economical operation,

Study the main environment problems and the solutions to resolve or mitigate them

Prove to the Environment that the solutions presented are effective

Make the risks analyse and the prevention measures

Instruct and inform the workers of all security and environment problems and solutions

Prepare the solution and the way to finish the operation

Execute the project of the final restoration of the site

The quarry exploitation has strong influence in the environmental systems by the land use and the operation

The control of the operation and of the impacts resulting of quarry’s activity can minimise this influence

It is possible and we must exploit the quarries in accordance with the nature and with it’s values.

A stork’s nest near the granite quarry

As an example