Articel

1. Influence of Geological Conditions to the Underground Mining
Natural resources occur naturally within environments that exist relatively
undisturbed by humanity, in a natural form. Natural resources have been exploited for
almost two centuries. Mining is one of the important to sufficient of the human needs.
Making decisions about mining operations is becoming increasingly difficult and
sophisticated. On the one side lie the demands of the national economy for raw materials
produced by the mining industry, and on the other the ever more complicated geological
and technical mining conditions.
Mining techniques have dramatically transformed over many years, with technological
advances improving efficiency and safety and health of our people, while minimising the
environmental impact of our operation. Sufficient knowledge of the mineral deposit, mining
technology, processing method, and cost are needed for undertaking a feasibility study and
proving the prospect worthy of being developed into a mine. Modifying the mining method
and introducing new, more powerful machines are actions that could raise the efficiency of
work procedures. The mine must remain a profit generator, which is not a simple task in an
environment of increasing labor costs and demands for better living.
The use of undergound space provides one of the best solutions for the development
of rapid communication routes. Although the cost is gretaer than for surface alternatives,
there are important advantages from an environmental and functional point of view,
distances are shortened, safety is enhanced, and there is less environmental impact.
Geological and geomechanical surveys are essential where any underground structure is
involved, during both the design and construction stages. At this geological stage, the
selection is preliminary study which is serve only as the basis for feasibility study. Then it
may be found necessary to revise details to results the final layout, but the basic principles
should be remained of the part.
Because of the uniquenes of the ore deposit, variations on each of these methods are
nearly limitless. Briefly, a few mining methods in accordance with the characteristics of
minerals and geological conditions would be used. There are three classes of underground
mining methods that recognized based on extent of support utilized. There are consist of :

2. a. Open Stope Method
This methods as like as unsupported methods, which the rock is essentially self
supporting, no major artificial support that is necessary to carry the load of overlying
rock. This methods divided in four methods, that are room and pillar mining, stope
and pillar mining, shrinkage stoping, and sublevel stopping.
b. Supported Stope Methods
Those methods that require some type of backfill to provide substantial of artificial
supports. That is for maintaining stability when exploitation persisted. Following are
considered as supported stope methods consist of cut and fill stoping, shrink and fill
stoping, stull stoping, and square set stoping.
c. Caving Method
The underground mining method that is essential, related to induced, controllled, the
ore body massive caving, the overlying rock or both. The caving method are compose
longwall mining, sublevel caving, and block caving.
Generally the differ of underground mining methods in approppriate with geological
conditions of ore deposit could be see below.
Tabel 1. Differ of Underground Mining Method Based on Extent of Support Utilezed
No Characteristics
Underground Mining Methods
Open Stope
Method
Supported Stope
Method
Caving Method
1. Ore Deposit
Strength
Relatively strong Ore depositmoderately
weak to strong
Relatively strong
2. Host Rock
Strength
Fairly strong Weak to fairly weak Weak to fairly strong,
should be jointed,
fractured, and cavable
3. Dip Sequence < 700
For vein deposit < 450
,
non vein > 450
Variable, > 600
or
vertical,falte if depositis
thick
4. Deposit Shape Tabular,lenticuler,
elongate
Tabular, irregular,
discontinuous
Tabular, massive
5. Thickness Approximately > 5
m
Approximately about 1
- 6 m
Variation
6. Uniformity Relatively uniform Moderate, variable Uniform& homogenous,
Moderate
7. Ore Grade Moderate to fairly
high grade
Fairly high grade Moderate

3. The fundamental principal of underground mining exploitation is choice the suitable
method in accordance with the characteristics of mineral deposit and be patient with safety,
technology, and economics limitation. Determining the underground mining should give
attention about :
- Dispersion characteristics of deposit or geometry (massive, vein, disseminated,
tabular, platy, sill, etc).
- Hydrology and geology characteristics (fault, joint, crack, groundwater,
permeability).
- Geotechnic characteristics (shear stress, shear strength, cohesi, rock mass rating,
etc).
- Technology (new machine and technlogy, technology authority, etc).
- Environment effect (tailing, subsidence, sedimentation, waste).
A typical development process of every mine could be presented in a steps (A. Dyczko, D.
Galica & S. Sypniowski, 2013), such as :
- Mineral exploration
- Deposit recognition
- Development of a model of the deposit
- Development and implementation of a mining plan
- Liquidation of the mining plant, reclamation and future development of the post
mining terrain.