Mining Rocks on an Industrial Scale

Rock Mining

Mining might have been the second earliest humankind activity after agriculture. The two endeavors were together the primary industries of the first civilizations. Little has changed in terms of the significance of these industries to humankind. From the ancient times to date, mining has played a significant role in human existence. Here the term mining refers to the extraction from the earth of any naturally occurring mineral substance for utilitarian purposes. After minerals have been extracted, they can be sold in open markets, enabling the countries that have these minerals to get paid by those that do not. This results in the countries that have minerals to be the great-powers of the world while those that do not to suffer from lower living standards. There are two general types of mined minerals geologically, these are:

Mineral: this refers to a naturally formed inorganic compound that has an orderly internal structure and a specific/characteristic crystal form, chemical composition and physical properties.

Rock: this refers to any naturally occurring aggregate made of one or more different types of minerals (Introduction to mining, n.d).

The Process

The core of mining in the extraction of minerals is to move excavations from the surface deep into the earth where the mineral deposits lie. Usually, these excavations (openings) into the earth surface are for allowing workers to access the underground deposits. However, boreholes are at times dug to extracts mineral deposits from the earth. These fields made up of boreholes are known as mines, even if the workers do not get to the geologic level of the mineral deposit. It is crucial to note that when a mineral has been determined to be economically viable with some confidence, the mineral occurrence is then referred to as ore or ore deposit. If the method used for excavating the mineral is entirely operated from earth's surface, the mine is called a surface mine. If the excavation method requires only openings into the ground for workers to enter below the surface of the earth, then the mine is called an underground mine. The characteristics of the procedure of excavation, its layout and the tools and equipments used in the mine differentiate each mining method. The characteristics or details are determined by the legal, geologic, economic, environmental and physical conditions that are associated with the mineral ore being excavated (Introduction to mining, n.d).

For people to use the rock deposits from earth they must collect them. Rocks from underneath the earth are collected though a process referred to as mining. The powerful equipments and machines used to extract rocks from deep inside the earth are referred to as miners. The process of gathering rocks from underneath the surface using machines is referred to as underground mining. Rocks have always been of importance to humankind; from the prehistoric use of rocks as tools, to today's use of rocks such as marbles and granite for countertops and floors. Other high value rocks such as diamonds are used to make jewelry. Geologists use several different methods to identify rocks. One way of identifying a rock is to conduct a scientific experiment. Another method which is quite simple is to scratch a rock against another to know its hardness or to rub a rock really hard on another hard surface so as to know its streak color (Zappa, 2011).

While on one hand geological classification of rocks based on their mineral content, origin or geological structure is useful for showing certain characteristics or trends, such classification of rocks provides little or no details to an engineer who is mining the rock. The engineer needs functional geo-mechanical classification of a rock for utilization for designs or for predicting the rock's performance in a structure (Heinio, 1999).

Geology is of primary importance in construction, this is because constructions take place only in two places; in or on the ground. Open excavations entails the removal of rocks or other material at the surface of the earth within specified boundaries. Open excavations depend on the conditions of the ground. Rock, particularly hard rock is removed by blasting or drilling. If the rock is suitably discontinuous, then it can also be ripped. The stability of the slope is also of importance in excavation, even though in certain areas some space for failure can be allowed due to cost. This applies particularly for situations where rock falls can occur. Various steps can be taken to stabilize slopes. Another challenge that can interfere with excavations is excess ground water and it can be handled by de-watering techniques or the deployment/erection of impermeable barriers around the excavation site (Bell, n.d).

Drill-ability of rock masses is based in the discontinuities, abrasiveness, grain size and the abrasiveness of the masses. The harder the rock is, the stronger the drill-bit required. Abrasiveness refers to a rock's ability to wear away bits. The size of fragments produced also influence the drill-bit's abrasiveness, this is because even though large fragments can cause scratching they cause relatively little wear compared to dust which causes polishing. Even bits tipped with diamond can wear because of polishing. Discontinuities only ease drilling if they are perpendicular to the drill-hole (Bell, n.d).

Spacing of holes for blasting is based on the fracture pattern, density, and the strength of the rock mass, in addition to the size of the charge (explosive mass). Generally, a kilogram of high explosive will bring down about 12 tons of rock. Good fragmentation eliminates the need for secondary blasting. Rocks that are characterized with high degrees of inter-granular cohesion with no specific orientation and high specific gravity resist crack initiation or elongation upon blasting. Rocks that are relatively brittle (little or no resistance to dynamic pressures) may result in a higher degree of pulverization only in the area immediately surrounding the blast holes and leave the area in between largely intact (Bell, n.d).