Among all the drilling method, Down The Hole(DTH) drilling is being used more and more widely and has very high efficiency for some cases. Here, we will introduce the specific application for DTH drilling as most import part of whole basic drilling knowledge.

Mining                                                 RC – Exploration

− Surface drilling                                  − Exploration

− Underground drilling                       − Grade control

Quarrying                                           Construction

− Aggregate and limestone                 − Civil engineering

− Dimension atone industry
Well drilling                                     Oil and gas

− Water well                                         − Shallow drilling

− Energy well                                       − Seismic

 

 

 

 

 

 

Surface Drilling  – Mining

Application Demands

− In surface mining productivity is probably the most important factor

− This requires high availability on equipment, good and predictable service life on drilling tools

− Customers usually have good follow up on costs and performance

− Drilling accuracy is an important factor as customers strive to use optimal drill and blast patterns

 

 

 

 

 

Three main types of holes are drilled in surface mining

− Blast holes

Hole diameter 115 – 229 mm (4½ – 9 in)

Hole depth 6 – 20 m (18 – 60 ft)

− Blast holes are production holes and will be filled with explosives

− Drilling accuracy is important to obtain good and even distribution of the explosives in the rock

− This will optimize fragmentation and facilitate further handling such as mucking, hauling and crushing

− Buffer holes

Hole diameter 115 – 152 mm (4½ – 6 in)

Hole depth 6 – 20 m (18 – 60 ft)

− Perimeter holes (pre-split)

Hole diameter 115 – 152 mm (4½ – 6 in)

Hole depth 6 – 20 m (18 – 60 ft)

 

− Pre-split and buffer holes are used for wall control

− This method reduces the amount of waist rock excavation and also the risk of rock fall from pit walls

− Usually smaller hole diameter than blast holes to carry less explosives

 

 

 

 

 

Underground Drilling – Mining

Application Demands 

− Underground mining is a very competitive industry so productivity is a very important factor

− Drilling accuracy is a must for good ore recovery and to avoid dilution

− Drilling accuracy is also important for optimal blasting pattern, good fragmentation and cost effective down stream operations

− This requires high availability on equipment, good and predictable service life on drilling tools

Application Cases

− DTH drilling in large scale mining operations underground such as Sub-level stooping and sub-level caving

− DTH is also used for drilling of holes for cables, ventilation or other “communication” needs betweendifferent areas or levels in the mine

Media Holes

− 90mm (3 ½”) – 254mm (10”)

− Media holes to connect levels, drifts, areas with each other is common in underground mining operations. Purpose of these types of holes is to                transport backfill paste, connect electric cables and waste water pipes

 

 

 

 

 

Quarrying aggregate – limestone

Application demands

− A wide spread of customers in this application, from small quarries serviced by contract drillers to big operations with own personnel and equipment

− Blast hole drilling

Hole diameter 90 – 205 mm (3½” – 8”)

Hole depth 10 – 30m

− Many quarries are located close to urban areas and environmental regulations put restrictions on drilling parameters

− Hole accuracy is important

− Noise restrictions give DTH drilling an advantage

Product selection criteria

− Price and performance are important for quarry/limestone drillers

− The smaller contractor is more price conscious and the big contractor or quarry owner is more performance focused

− Product availability, service and support are essential factors

− Drilling accuracy important for optimal drilling pattern and good fragmentation

 

 

 

 

 

Construction – Civil Engineering

Typical drilling applications

− In civil engineering DTH drilling is used for a lot of different applications

− Blast holes at construction sites used for removal of rock in road and railway projects, construction of HE plants etc

− Foundation drilling methods are used to reinforce or stabilize rock and soil in different construction projects

Geotechnical drilling

− Holes which is part of a structure or process created to stabilize and control rock and soil. Often used in combination with overburden drilling system.

− Soil Nails

− Earth / Rock Anchors

− Umbrella drilling

− Sinkhole repair

− Compact grouting

Product selection criteria

− Foundation drilling is usually made by specialized companies

− High demand on product performance in difficult drilling situations

− Trouble free drilling in mixed ground conditions, many times with casing systems

− Service and support is important

 

 

 

 

 

Water Well Drilling

Application demands

− Lots of “one rig” companies in this application

− Geothermal drilling has increased the interest and more performance conscious drillers have entered the field

− Lot of drilling in conditions that requires casing tube systems

− Product performance essential as drilled depths sometimes are over 600 m (2250 ft)

− Hole size 115 – 400 mm (4½” – 16”)

Geothermal Well Drilling

− Primarily, these contractors are engaged in energy wells for private houses, hospitals and industry buildings for heating in winter and cooling in summer

− Normally it works together with heat pump to get best efficiency, and it is being developed very well in China due to environmental protection

 

 

 

 

 

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