Stoping is the process of extracting the desired ore or other mineral from an underground mine, leaving behind an open space known as a stope. Stoping is used when the country rock is sufficiently strong not to cave into the stope, although in most cases artificial support is also provided. The earliest forms of stoping were conducted with hand tools or by fire-setting; later gunpowder was introduced. From the 19th century onward, various other explosives, power-tools, and machines came into use.
There are two principal phases of underground mining: development mining and production mining. Development mining is composed of excavation almost entirely in (non-valuable) waste rock in order to gain access to the orebody. There are six steps in development mining: remove previously blasted material (muck out round), Scaling (removing any unstable slabs of rock hanging from the roof and sidewalls to protect workers and equipment from damage), installing support or/and reinforcement, drill face rock, load explosives, and blast explosives. Production mining is further broken down into two methods, long hole and short hole. Short hole mining is similar to development mining, except that it occurs in ore. There are several different methods of long hole mining. Typically long hole mining requires two excavations within the ore at different elevations below surface, (15 m – 30 m apart). Holes are drilled between the two excavations and loaded with explosives. The holes are blasted and the ore is removed from the bottom excavation.
The carbon steels have already been discussed with regard to their corrosion problems. With welded carbon steel piping there is the additional problem of preferential corrosion along the weld unless the pipe has been normalized after manufacture.
One of the most important aspects of underground hard rock mining is ventilation. Ventilation is required to clear toxic fumes from blasting and removing exhaust fumes from diesel equipment. In deep hot mines ventilation is also required for cooling the workplace for miners. Ventilation raises are excavated to provide ventilation for the workplaces, and can be modified for use as emergency escape routes. The primary sources of heat in underground hard rock mines are virgin rock temperature, machinery, auto compression, and fissure water. Other small contributing factors are human body heat and blasting.
There is usually no direct connection from a mine railway to the mine's industrial siding or the public railway network, because of the narrow gauge track that is normally employed. In the United States, the standard gauge for mine haulage is 3 ft 6 in (1,067 mm), although gauges from 18 in (457 mm) to 5 ft 6 in (1,676 mm) are used. Original mine railways used wax-impregnated wooden rails attached to wooden sleepers, on which drams were dragged by men, children or animals. This was later replaced by L-shaped iron rails, which were attached to the mine floor, meaning that no sleepers were required and hence leaving easy access for the feet of children or animals to propel more drams.
TRC Conveyor Belting is a conveyor belt manufacturer and stockist, specialising in new conveyor belting. All supplied conveyor belting is manufactured to SANS 1173 or DIN specifications depending on the customer’s requirements and carries a full international guarantee. Original test certificates (which can be supplied on request) will confirm that the product is of the highest quality with regards to pull out strength, abrasion and adhesion.
TRC has its own slitting, splicing and warehousing facilities separate to those of Conveyor & Plant Services, and holds a large variety of standard specifications in stock. Therefore, products can often be quoted ex-stock; especially in a break down situation.
As well as the standard grade "N" rubber conveyor belting, stock of various heat resistant and chevron belting is also held and Grade "M" rubber conveyor belting, steel cord and solid woven PVC can also be quoted on.