In the previous topic we learned that the economics of mining is particularly related to the amount of ore that can be produced and the amount of waste rock that must be moved. That makes underground mining particularly suited to structurally compact ore bodies with high grade ores which don’t require an extensive network of access tunnels through worthless rock and which don’t involve large qualities of gain being brought to the surface with the valuable ore and deeper deposits where excessive depth of overburden makes the costs of accessing the ore prohibitive. In this topic, we will take a look at those situations in some more detail. Mineral and oil deposits come in many different forms and contain many different types of minerals. A full consideration of the geological origin of oil deposits is well beyond the scope of the current course. In this topic, we’ll only consider those mineral deposits which are relevant to our discussion of underground mining. Classifications of mineral deposits can be formed on many different basis. These include the genetic geological origin of the deposit that is how it is formed, the minerals it ….Read more
The choice of an underground mining method depends on a range of factors and these include; the size and shape of the deposit, the orientation or slope of the deposit, the depth of the deposit, geological structures, characteristics of the ore and the surrounding rocks and issues with gas and water. In combination, these factors allow us to determine an appropriate arrangement and sequence for mining operation but before going on to look to see how they combine to mine specific geological ore bodies, let’s have a look and familiarize ourselves at the different basic elements of an underground mine and there basic purpose.
Before an underground deposit can be mined it must be accessed. Access to an underground ore body is achieved through a combination of shafts which are vertical tunnels, drifts and drives which are horizontal tunnels and declines and ramps which are inclined tunnels. Access provides for getting people and equipment to the ore body, getting mined ore and waste out of the mine, ventilation and emergency egress and getting waste and tailings in to backfill the mine.In general the access arrangement for people, equipment, ore ….Read more
In model 1 with Stephen, and in the previous topic, we saw that the geological aspect is one of the main factors that affect the design of a surface mine. What are the characteristics and other aspects should be taken into a code for the final configuration of the surface mine. Between them, we have to take into account of the safety, economics, and the recovery of the material.
In the next topics we will see how all this could be achieved. But before that, let’s have I look at which are the main physical elements that make up a surface mine. When we create an excavation with the purpose to mining a deposit, the excavation is called, pit. The pit is a hole in the ground with sloping sides leading to the pit floor. The waste from the hole in the ground is placed on a dump. In a later stage, we will discuss what ….Read more
In the previous topic, we saw which are some of the advantages that can make the surface open pit mining methods superior method compared to the underground mining. However, underground mining has its own advantages. And finally, the ultimate decision to mine from the surface or from underground comes down to the specific characteristics of the deposit. In particular, mineral deposits can occur in very different forms and they may contain a very wide variety of minerals.
In this topic, we will try to see which are and which are the characteristics of the deposits that are most suited for surface mining. Generally, it’s easy to think that mineral deposits that are already outcropping to the surface or lying at very shallow depths from the surface are easily extracted using a surface mining method. From the geological point of view, we have several mineral deposits that are in these conditions and that can be extracted completely from the surface, and that we can find also some deposits for civil constructions.
For civil construction, we can consider the deposits of sand, clays, gravel, rocks, and all of the ….Read more
Mining Engineering is a lot about applying the knowledge of applied science and Engineering Mechanics to the successful extraction of useful geological resources. So in this first module we will overview the mining process in its entirety and identify those aspects which are the realm of the mining engineering. Then in the next three modules we will look at the specifics of mining engineering in greater detail. We will devote this first topic to identifying the steps in the mining process, and to introducing the terminology that used in the mining industry and that will be used throughout this course.
The mining process begins with finding a new mineral deposit and it ends when the mine is abandoned after it has been rehabilitated. Basic steps in the mining process are:
- Mineral exploration to find a new deposit.
- Economic Assessment of the deposit to a prices viability mine design which we’ve a safe, stable and financially viable operation. This is the main job of the mining engineering.
- Environmental impact assessment mitigations
- Beneficiation of the mining product
- Handing on the mining products and wastes
- Mine closure in site remediation
These headings services as the list of ….Read more
In this topic we will discuss what constitutes a rock mass and its relevance for engineering.in this photo, you can see a rock face and what is quite clear is that the rock is not homogeneous. Compare to this specimen of sandstone, which has a uniform color and no clear planes crossing it. In contrast, the photo shows many lines, vertical lines and horizontal lines. Vertical lines are simply referred to as discontinuities and discontinuities fall into two categories. They’re called faults if some relative movement has taken place. As we can see on this second photo, you can see that the stripes of color do not align from left to right. There’s been some vertical movements that offsets the stripes. This happens along the faults. If there is no relative movement observed, these are typically called joints.
The rock mass, as a whole is a combination of blocks of homogeneous rock, also called rock matrix, or intact rock separated by discontinuities. The rock matrix has certain properties depending upon its mineralogy, origin, the degree of weathering, and the discontinuities would have different properties.
We’re going to introduce in this topic the two key variables required to define the fundamental behaviour of materials. These variables are stress and strain.
In many engineering applications it is required to assess how a structure deforms or behaves under a load. Making such an assessment requires some knowledge about the material constituting the structure itself. For example you couldn’t sit on the chair made of rubber. You need a stronger material like hard plastic or timber. So when it comes to characterising a material there are two questions we need to answer. One is, how much does a material deform under a load? The second questions is, how much load does it take for the material to break? And to answer these questions we need to define stress and strains. Let’s see why with an experiment.
We take a short rubber band and we’re going to place this rubber band in intention. We start by measuring its initial length, which comes to 54 millimetres and we place weights on this hanger to stretch the rubber band. It now stretched to 62 millimetres. Let’s ….Read more
How Explorers develop an exploration strategy, how they develop an exploration model and design an exploration program and select the optimal exploration tools to carry out that program. As usual of the talk will end with a series of learning points from this talk.
There are two fundamental truths about the exploration industry; the first is that most exploration programs are doomed to failure. It’s been estimated that only 1 in 5000 or even 10,000 of all prospects will eventually be shown to halt deposits that can support a viable mining operation. Therefore the odds are that the vast majority of exploration programs will end up with nothing to show for the dollars they’ve spent. The second fundamental truth is that most Explorationists has more ideas than they have funding to test those ideas. These two truths mean that simply playing the odds and drilling hundreds of targets is a short cut to financial ruin. If they are able to be successful, companies need to develop their explorations strategy with a huge amount of thought and research. The old adage of failing to prepare is preparing to fail holds particularly true to the exploration industry.
In the previous topic, we considered methods of stope mining were the stopes were intended to stay open and collapse and collapse of the roof was not an intended outcome. In some situations however, it may be permissible or even desirable that the roof of the mine collapse to fill the stope as mining proceeds. These methods are called cave mining or caving techniques. Cave mining has the advantage of greater recovery since less of the ore has to be left behind to support the rock above and the resource is not consumed in trying in stabilize the roof. The disadvantages however are; the subsidence occurs in the ground surface above, that progressive collapse may be difficult to control may be unpredictable and hence dangerous and as the roof collapses before or during ore removal, the ore is contaminated with waste which must then be removed. As with stoping, caving is adaptable to both inclined and flat deposits. Let’s start by taking a look at caving in flat deposits through a technique known as long wall mining, commonly used in the mining of coal seams. In long wall mining, flat ….Read more
Here is some history of the Witwatersrand Gold Style Ore Deposits as they related to South Africa since the arrival of the Dutch and the southernmost tip of the continent in 1652. The Dutch set up a small fort where Cape Town stands today and started Market Gardens as a place that the Dutch East India Company ships to shelter and to restock with freshwater and provisions on the long journey between Holland and East Indies. The East Indies was a vital spice trading destination for the Dutch.
As time went on the tiny community expanded and some of the Dutch were allowed to move into the surrounding area to set up new farms on the condition that they still sell their produce to the Dutch East India Company to supply the expanding ship traffic. This arrangement although it was very successful only lasted for a fairly short time before these farmers or Boers as they became known became frustrated by the restrictions set by the company and they started breaking free of the bond and moving inland in their wagons with the Bible in one hand and the rifle in the other.
Towards the end of the ….Read more