Case Study Research

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shotcrete_tunnelling_robotic_1_image_.32585308The benefits of mechanized shotcrete application can be evaluated by three categories:

1) Increased production
2) Better quality shotcrete in-situ
3) Improved worker safety

Increased Production

A multitude of reasons exists which allows increased production with the use of a shotcrete robot, most of which are due to the elimination of the human fatigue factor.

The predominant reasons are as follows:

Increased concrete hose diameter – Some spraymobiles are equipped with 102mm

(4.0 in) hoses. Hand nozzling will typically use a 51mm (2.0 in) hose diameter. The weight of shotcrete in the 102mm (4.0 inch) line is equal to 18.3 kg/m (12.3 lbs/ft).
With the human fatigue factor eliminated, shotcrete volumes can increase
dramatically. Hand nozzling volumes can range from 7-9 m3/hr (9-12 yd3/hr), while mechanized spraying can easily reach volumes of 20m3/hr (26 yd3/hr). This is particularly beneficial in larger diameter tunnels, stations, galleries or when shotcreting for the final lining is being utilized.

Higher Quality Shotcrete In-Situ

There are combinations of capabilities with mechanized spraying that allow shotcrete to be placed with improved in-situ properties. Some of these are:

1. Dedicated maximum air volume for optimum compaction
2. Lance mounting is automatically held parallel to the axis of the tunnel
3. New robotic manipulating capabilities also allow for automated nozzle adjustments to be made to maintain proper standoff distance as well as nozzle angle to the substrate.

mining_tunnel_people_image.32585915Improved Worker Safety

The contributions to a safer working environment via robotic spraying are clear. With use of a remote control, crews are able to remain in supported areas while letting the reach of the spraymobile apply shotcrete in the newly excavated areas. In areas that require a combination of rock bolts and shotcrete, the bolting crews can take advantage of working in a supported environment where an initial layer of shotcrete has been sprayed for temporary support. Click Here Read Full Study

Shotcrete Robotic Spray Effective – Case Study Kidd Creek Mine Canada

The Kidd Creek Mine is located in Timmins, Ontario, Canada, where copper-zinc-silver deposits were discovered in 1963. Owned by Falconbridge Limited, it was put into production in 1965 with an open pit mine, which was excavated from 1965 –1977. Subsequently, the ore body has been mined through three separate shafts known as the

No.1, No.2, and No.3 mines.

For years, Kidd Creek used bolt and screen construction for primary ground support. Dry shotcrete was used as secondary reinforcement and for repair where needed. At the end of the 1990s the company began searching for a better, faster, safer ground support method.

In approaching the search for a new ground support protocol, the challenge was to
develop a system that would be safe and economically feasible to apply in a complex and
deep mining environment, and would be accepted by workers in the mine. They needed a viable new ground support method that would reduce exposure to unsafe working conditions, and meet stringent government and company regulations.Robotic_Shotcrete_Applications_for_Mining_and_Tunnelling.32590521

Early in the process, the workers were focused simply on finding a better, faster way of applying dry shotcrete – they were not considering wet shotcrete. The mine had tried wet shotcrete in the early 1980s and it was not a success, so they were reluctant to explore that alternative. In 1999 the mine explored new technologies to help them meet their goal. They recommended an innovative wet mix shotcrete system using the latest automatic delivery and robotic concrete spray equipment as a solution that would meet all of the Kidd Creek goals – increased productivity, enhanced safety and improved structural performance. Ultimately, their goals were in fact exceeded as outlined in this case study. 

In July of 2000 the Falconbridge Board of Directors approved the development of a new mine on the Kidd Creek site. Known as Mine D (Deep), it will extend the mine from a depth of 2070 M (6800 ft.) to 3050 M (10000 ft.). When completed it will be the deepest base metal mine in the world, and it requires a significant infrastructure, including a new internal underground shaft, hoisting facilities, and approximately 15 kilometers (9miles) of development. Started in 2001, the project is estimated to take four years to complete and approximately 100,000 m3 (130,000 yd3) of construction concrete and 60,000 m3 (78,000) of shotcrete will be used.

As a result of the success of the SFRWS in field trials and subsequent use, Kidd Creek Mine management decided to use the system in the construction of Mine D. The mine commissioned a state-of-the-art on-site batch plant with capacity to feed two 200 mm( 8”) diameter cased boreholes to depths of 1400 m (4600 ft.) and 1460 m (4800 ft.) respectively. Five wet shotcrete spray mobiles and seven transmixers were acquired to meet the needs of the mine.
Tenders were let and the mine chose the MSV shotcrete sprayer as supplied from MBT’s manufacturer. The MSV was designed especially to handle the underground environment. It features a robust carrier and utilizes some of the most effective and efficient drive components on the market. It has an overall tramming length of only (7.3m) 24 ft. and a height of (228 cm) 90 inches. The sprayer was not only capable of higher and safer tramming speeds, it was also able to cover numerous headings in one shift.

As of late summer 2003, the Mine D project had reached a level of 2438 m (8000 + ft), with more than 14,000 m3 (18,200 yd3) of shotcrete applied using the MBT MSV spraying units. An indicator of the improved safety is the fact that since fully implementing SFRWS as primary ground support in early 2002, there has not been oneloose related injury. Click Here Read More Analysis