After the physical mine infrastructure has been built, production activities include drilling, blasting, excavation, loading and transporting broken ore. Waste rock is piled up near the edge of the pit and spreads both horizontally and vertically. The waste dump is also tiered and stepped, to keep rocks from falling into other parts of the site. These tailings ponds are often toxic due to the presence of unextracted sulfide minerals. After mining finishes, the mine area must undergo rehabilitation to minimize environmental damage.
This step in the mining process is critical to ensuring the sustainability of the land for future use. First, waste dumps are contoured to flatten them out and stabilize them. If the ore contains sulfides, it is covered with a layer of clay to prevent rain and oxygen from oxidizing the sulfides into sulfuric acid, which is also known as acid mine drainage.
Then, the waste dump is covered with soil, vegetation is planted, and the area is fenced to prevent livestock from eating the newly planted vegetation. This layer will eventually erode but in the meantime, it will allow the leaching of heavy metals to occur slowly enough for the surrounding environment to absorb them.
The open pit is also fenced off to prevent access, and over time fills up with groundwater unless the groundwater levels are excessively deep. Our approach to mining. A world-class portfolio. Mail More Posts 2. Recent Posts. Our Directory is a simple tool that has evolved into a remarkable business system with Would you buy a new car without taking out insurance? Would you buy a house To view more Articles, please visit our Leads 2 Business Blog. If you are interested in Waste dumps are contoured to flatten them out, to further stabilise them.
If the ore contains sulfides it is usually covered with a layer of clay to prevent access of rain and oxygen from the air, which can oxidise the sulfides to produce sulfuric acid, a phenomenon known as acid mine drainage.
This is then generally covered with soil, and vegetation is planted to help consolidate the material. Eventually this layer will erode, but it is generally hoped that the rate of leaching or acid will be slowed by the cover such that the environment can handle the load of acid and associated heavy metals. There are no long term studies on the success of these covers due to the relatively short time in which large scale open pit mining has existed.
The dumps are usually fenced off to prevent livestock denuding them of vegetation. The open pit is then surrounded with afence, to prevent access, and it generally eventually fills up with ground water. In arid areas it may not fill due to deep groundwater levels.
Figure 3. An open-pit sulfur mine at Tarnobrzeg, Poland undergoing land rehabilitation. Gold is generally extracted in open-pit mines at 1 to 2 ppm parts per million but in certain cases, 0. Nickel, generally as laterite, is extracted via open-pit down to 0.
Coal without stone bands 6. Preferably non-forest land. Availability of adequate place for dumping. Stripping ratio depending on quality of the coal ISN Advantages of opencast mining There is no problem of ventilation There is no problem of Roof control, supports There is no problem of lighting in daytime.
Quick returns on capital investment. There is no risk of gas explosion. Large-scale mechanisation is possible. Gestation period is less ISN Thank you all, ISN. Total views 50, On Slideshare 0. From embeds 0.
Number of embeds Downloads 0. Shares 0. Comments 0. Likes You just clipped your first slide! Clipping is a handy way to collect important slides you want to go back to later. Now customize the name of a clipboard to store your clips. Visibility Others can see my Clipboard.
Cancel Save.
0コメント