Stages of Activities in Mining Business
December 10, 2015 - Uncategory
Mining is a set of processes starting from site prospecting to marketing. In general, mining process involves prospecting, exploration, mining, processing, transportating, and marketing.
Prospecting is the search for, study and discovery of valuable mineral deposits. In other words, the main purpose of this activity to find the presence or indication of presence of ores or minerals to warrant further exploration. If no significant deposit is found at this stage for further exploration, the mining activities stop at prospecting. Wasteful spending will result in additional activities. This stage is often skipped when the deposits are assumed to be sufficient for direct exploration.
The methods of prospecting, among others, are float tracing and geological mapping and deposit analysis. Float tracing method is employed especially on river tributaries and easier performed during the dry season. Prospectors look for deposited floats of the intended minerals originated from erosion processes of mineralization zone on hillsides and washes that end up on river banks. By tracing the floats from downstream to upstream, mineraliatio zone could be found upstream. For this method, most of the lithology of the area should be known. Geological mapping and deposit, the second method, is performed when the area lithology has not generally been studied and more detailed data area needed.
Exploration is the next set of activities undertaken after prospecting or when deposits have been discovered. This stage is to acertain the presence of the intended mineral deposits by collecting data on shapes, size, location, quality (concentration) and physical characteristics of the deposits.
Besides getting the data of distribution and thickness of the deposits, this activity includes sampling of the deposits and reclamation soil. This exploration stage has a very important role in the reclamation stage, because during this stage we can know and understand all the components involved in the ecosystem before mining.
In general, there are two stages of exploration, ie. initial exploration and detailed exploration. The initial exploration involves literature study, survey and mapping, and feasibility study. After the initial exploration yields data for significant deposits, the detailed exploration will follow. The main activity at this stage is by sampling in closer proximity, ie. increasing the number of testing wells to gain more detailed data on the distribution and thickness (volume) of the deposits, and horizontal and vertical quality distribution. From this tight sampling, the deposits can be measured with more uniform classification and smaller risk (<20%), and thus the mine planning can be made more detailed and risk can be avoided.
The more accurate knowledge and data on the depth, thickness, slope, and distribution of deposits in 3D (length-width-thickness), and data on sampled rock hardness, ground water condition, and structural distribution (if any) will facilitate the planning for the mine development. The width/size of the opening or slope of mine is also important to plan the monthly/yearly production and choose the correct equipment and other support priorities.
The next stage after the series of initial studies is the last stage to determine whether it will be advantageous to mine the availble deposits. The bases to decide include technical and economical considerations based on the currently available technology, and the attention to workers’ safety and environmental conservation. If it is not feasible, data will be archived.
Mine development will commence when a significant deposit has been discove and the amount is measured. The deposits can be classified into three categories: 1) Measured deposit is when the maximal error rate is 20% and sampling from drilling has been obtained; 2) Indicated deposit is when the maximal error rate is 40% and drilling has not been performed; 3) Implied deposit is when the error rate reaches 80% and drilling has not been performed. And when it is at the development stage, the deposit has already been classified as measured.
Mine development is performed to plan the technical, economical, and environmental activities of mining, so that the processes take place well and safely for the environment.
Preparation/construction is an event to prepare the mining facilitaties before mining operation commences. The work include the making of mine access roads, harbors, offices, repair shop, employ housing, communication facilities, and power station for the mining operation and processing facilities for the mined materials.
Mining can be categorized into three types: open mine, underground mine and underwater mine. Open mines can be grouped into strip mine quarry, open cut, alluvial mine, and spray mine. Underground mines include room and pillar, longwall, caving, open stope, supported stope, and shrinkage. The mining system that utilizes dredging ships on shallow water is considered an underwater mining.
1. Open Mining Method
Open mining is generally defined as the mining of deposit exposed to open air. The general stages of open mine include areal cleaning, peak cutting and storing it at a certain location, opening and excavating overburden (cover soil) with or without explosives and moving it to a designated disposal area, mineral excavation or exploitation, and transporting it to a stockpile for processing and marketing and for reclamation (to be discussed later).
2. Underground Mining Method
Underground mining is generally defined as the mining of deposits with no direct contact to open air. The stages in underground mining consist of building main road, installing supports, making forward holes for production, ventilation, drainage, and other facilities for underground mining. After mining operation undergoes with or without explosives, materials are transported to the stockpile for processing and marketing.
3. Underwater Mining Method
Underground mining is a method of obtaining materials from alluvial deposits, under shallow or deep water. The main equipments for underwater mining is dredge ships.
In general, mining is an activity to obtain the deposits, which will be processed futher and marketed. The process consists of excavating and transportating either to a processing plant or direct market.
The deposits that have been mined usually will be processed at a processing plant. This is because the deposits are usually contaminated with waste materials and the market requires certain specifications. Raw/unprocessed materials usually yield lower prices than the processed ones. The processing also reduces volumes, which in turn reduces transportation cost, increases the value of materials, and reduces the chemical compounds unwanted at the smeltering plants.
There are three types of processing: physical, physical and chemical without metal extraction, and physical and chemical with metal extraction. Physical processing involves grinding, washing, drying, and low temperature heating. An example for this process is that of coal mining. The example for physical and chemical processing without metal extraction is in low scale coal mining using chemical reagents. The physical and chemical processing with metal extraction is for ore mining of precious and basic metals.
After processing, deposits can be marketed to the consumers. There is a business relationship between mining companies and consumers whether it is in long-term contracts or spot (transient) purchases. Long-term contract is when marketing to the same customers occurs for at least a year, whereas spot purchase takes place when there is a single transaction or a couple of shippings of orders.
Reclamation is an activity to restore the environment after it is changed by mining or other events. This reclamation process usually involves with the replanting of vegetation at the affected areas. The process is undertaken because mining changes the physical, chemical and biological characteristics of the area, such as the quality and flow of water , soil characteristics, vegetation patterns, animal habitats, etc. These changes have to be managed to avoid further negative impacts on the environment, such as erotion, sedimentation, poor drainage, weed and pest infestations, pollution of surface and ground water by toxic chemicals. The two activities in reclamations are the restoration of former mines to improve the disturbed land, and the preparation of the area for further utilization.