Original Title: 6 Processes of Open-pit Mining from Perforation, Blasting to
Dumping The mining technology of open-pit mine is relatively simple, mainly
including drilling, blasting, mining, loading and transportation, and rock
dumping. Next, we will talk about the mining technology of open-pit mines in
detail. I. Perforation work Perforation is the first working procedure of open
pit mining. In the whole process of open pit mining, the cost of perforation
accounts for about 10%-15% of the total production cost. 1. Down-the-hole drill
The down-the-hole drilling machine has the advantages of large drilling angle
change range, high mechanization degree, reduction of auxiliary operation time,
improvement of the operation rate of the drilling machine, flexibility of the
down-the-hole drilling machine, light equipment weight and low investment cost,
and particularly can control the ore grade by drilling various inclined holes,
eliminate toes, reduce large blocks and improve the blasting quality. Therefore,
the down-the-hole drill is widely used in small and medium-sized mines at home
and abroad, which is suitable for medium hard rock drilling. 2. Rotary drill
Rotary drilling rig is a new type of drilling equipment developed on the basis
of rotary drilling rig, which has the characteristics of high drilling
efficiency, low operation cost, high degree of mechanization and automation, and
is suitable for drilling operations of various hardness of ore and rock. At
present,
dth
rock bit, it has become a common drilling equipment used in open-pit mines
all over the world. 3. Rock drilling jumbo Drill jumbo is a new type of drilling
equipment with the development of mining industry. One or a plurality of rock
drills are arranged on a special drill boom or a rack together with an automatic
propeller, and a traveling mechanism is arranged, so that the operation of the
rock drill is mechanized. II. Blasting work The purpose of blasting work is to
break the hard solid ore rock and provide the excavation material with
appropriate size for mining and loading work. In the total cost of open-pit
mining, blasting cost accounts for about 15% -20%. The quality of blasting not
only directly affects the efficiency of mining, transportation, coarse crushing
and other equipment, but also affects the total cost of the mine. 1. Shallow
hole blasting Expand the full text The diameter of the hole used in shallow hole
blasting is small, generally about 30-75 mm, and the depth of the hole is
generally less than 5 meters,
Tapered
Rock Bit, sometimes up to about 8 meters. If the drilling jumbo is used for
drilling, the depth of the hole can be increased. Shallow-hole blasting is
mainly used for the excavation of open-pit mines or quarries, caverns and
tunnels with small production scale, secondary blasting, the treatment of new
open-pit mine hills, the formation of hillside open-pit single-wall ditch
transportation channels and other special blasting. 2. Deep-hole blasting
Deep-hole blasting is a blasting method that uses drilling equipment to drill
deeper boreholes as the charging space of mining explosives. The deep-hole
blasting of open-pit mine is mainly the production blasting of bench. Drilling
equipment for deep-hole blasting mainly includes down-the-hole drill and roller
drill. It can be used to drill vertical deep holes or inclined blast holes. The
charging of inclined blast holes is more uniform, and the blasting quality of
ore and rock is better, which creates good conditions for mining and loading
work. In order to reduce the seismic effect and improve the blasting quality,
such measures as millisecond blasting in large area, interval charging in
blastholes or bottom air interval charging can be taken under certain
conditions, so as to reduce the blasting cost and obtain better economic
benefit. 3. Chamber blasting Chamber blasting is a blasting method in which more
or a large amount of explosives are loaded in the tunnel of the blasting
chamber. Open-pit mines are used only during the capital construction period and
under specific conditions, and quarries are used when conditions permit and when
the demand for mining is high. 4. Multi-row hole millisecond blasting method In
recent years, with the rapid increase of the excavator bucket capacity and the
production capacity of the open-pit mine, the normal excavation blasting of the
open-pit mine requires more and more blasting quantity each time. Therefore,
large-scale blasting methods such as multi-row-hole millisecond blasting and
multi-row-hole millisecond extrusion blasting are widely used in open-pit mining
at home and abroad. Advantages of multi-row millisecond blasting: The one-time
blasting quantity is large, the blasting times and the blasting avoidance time
are reduced,
Mining Drilling
Equipment ,
DHD
Drill bit, and the utilization rate of the stope equipment is improved; The
broken quality of ore and rock is improved, and the boulder rate is reduced by
40 to 50% compared with that of single-row hole blasting; The efficiency of
perforating equipment is increased by about 10% -15%, which is due to the
increase of working time utilization coefficient and the decrease of the number
of operations of perforating equipment and filling area after blasting; Improve
the efficiency of mining and transportation equipment by about 10% -15%. 5.
Multi-row hole differential extrusion blasting method It refers to the multi-row
millisecond blasting in the case of residual muckpile in the working face. The
existence of muck pile creates conditions for extrusion. On the one hand, it can
prolong the effective action time of blasting and improve the utilization of
explosive energy and crushing effect; on the other hand, it can control the
width of muck pile and avoid the scattering of ore and rock. The millisecond
interval of multi-row hole millisecond extrusion blasting should be 30% ~ 50%
longer than that of ordinary millisecond blasting, and 50 ~ 100ms is often used
in open-pit mines in China. The advantages of multi-row hole millisecond
extrusion blasting are as follows: (1) The ore rock crushing effect is better.
This is mainly because the front is blocked by the slag heap, and each row of
boreholes, including the first row, can increase the charge and be fully crushed
under the extrusion of the slag heap; (2) The muckpile is more concentrated. For
the mine using railway transportation, it is not necessary to dismantle the road
before blasting, so as to improve the efficiency of mining, loading and
transportation equipment. The disadvantages of multi-row hole millisecond
extrusion blasting are as follows: (1) High explosive consumption; (2) The
working platform is required to be wider to accommodate the ballast pile; (3)
The blasting pile height is large, which may affect the safety of excavator
operation. III. Blasting measures near the slope With the downward extension of
the open-pit mine, the problem of slope stability has become increasingly
prominent. In order to protect the slope, the blasting near the slope should be
strictly controlled. According to the experience at home and abroad, the main
measures are millisecond blasting, presplitting blasting and smooth blasting. 1.
Adopt millisecond blasting to reduce vibration One of the main functions of
millisecond blasting is to reduce the seismic effect of blasting. In order to
give full play to the shock absorption effect of millisecond blasting, the key
is to try to increase the number of blasting segments and control the
millisecond interval. 2. Adopt presplitting blasting to isolate the slope. The
presplitting blasting near the slope is to drill a row of dense parallel
boreholes along the slope boundary, fill each hole with a small amount of
explosives, and detonate before the excavation zone is blasted, so as to obtain
a crack with a certain width and running through each borehole. Due to the
separation of the excavation zone from the slope by the pre-fracture, the
seismic wave of the subsequent excavation blasting will produce a strong
reflection on the fracture surface, which will greatly reduce the seismic wave
passing through it, thus protecting the slope. 3. Adopt smooth blasting to
protect the slope. Smooth blasting near the slope is to drill a row of dense
parallel boreholes along the boundary line, fill a small amount of explosives in
the holes, and then blast after the excavation of boreholes, so as to form
parallel rock walls along the dense boreholes. The difference between smooth
blasting and presplitting blasting lies mainly in the initiation time. The
initiation of smooth holes is later than the previous rows of excavation holes,
usually 50 to 75 ms later. In addition, another measure is to control the
blasting of the last few rows of boreholes. The explosive quantity and
resistance line of the last rows of boreholes near the slope should be reduced,
which is called "buffer blasting", which can reduce the damage of drilling
blasting to the slope. IV. Purchase, loading and transportation Acquisition and
loading: Mining and loading operation is to use loading machinery to excavate
ore rock directly from the ground or blasting pile, and load it into the
carriage of transport machinery or unload it directly to the designated place.
It is the central link in the process of open-pit mining, and other production
processes such as drilling and blasting, transportation and so on serve for
mining and loading. Main mining and loading equipment: excavator, dragline,
hydraulic shovel and rubber-tyred front loader. Transportation In the process of
open-pit mining, the capital construction investment of mine transportation
accounts for about 60% of the total investment of mine capital construction, and
the transportation cost and labor volume account for more than half of the total
ore cost and labor volume respectively, which shows the important position of
transportation in open-pit mining. Transportation modes of open-pit mine:
automobile transportation, railway transportation, belt transportation, slope
skip lifting transportation and combined transportation, among which dump truck
transportation is the most common. Mining and transportation are inseparable,
and they influence and restrict each other. At present, the development trend of
mining and transportation technology is mainly reflected in the large-scale
mining and transportation equipment, the integration and continuity of mining
and transportation links, and computer automation. 5. Rock discharge Rock
dumping is the operation of the transport terminal, which transports the
stripped topsoil and waste rock to the waste rock yard for disposal. Rock
dumping process: rock dumping by railway transportation, road transportation and
belt transportation. 6. Dump Waste dump (waste rock dump): a place where
stripped materials are piled up, which refers to the place where mining wastes
are discharged in a centralized manner. According to the stacking sequence, the
dump can be divided into single-bench dump,
overburden
drilling systems, covering multi-bench dump and slope-pressing multi-bench
dump. The dump is mainly divided into road transport dump, railway transport
dump, belt transport dump and hydraulic transport dump according to the dumping
process. Return to Sohu to see more Review of past issues Responsible Editor:.
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