Sandvik Mining and Construction is inviting interested parties to see its new generation Borer Miner MF420 in operation at the factory in Zeltweg, Austria. The machine will be presented January 25 to February 5, 2010. After cutting through a 1,000 m3 concrete block at our test facility, the machine will also cut through 30 m3 of solid ice! The 240-t MF420 offers a cutting width of 6,100 mm and cutting heights up to 3,600 mm.
Anyone intersted in seeing the demonstration should contact [email protected]. The MF420 Borer Miner is based on the design of the well proven Marietta Borer Miner 1012. Several of these machines have been in operation for many years centuries in a number of Canadian potash mines. The MF420 is a boring type, variable height and width-machine which cuts and delivers material to auxiliary haulage equipment in one continuous operation. The machine may be used to drive entries, mine rooms and extract pillars as rapidly as haulage equipment can remove material to the main haulage way. The instantaneous advance rate of the machine can be as high as 23.5 t/min or 0.5 m3/min.
The miner consists, basically, of two sections: the cutting and conveying mechanisms, which are jointed together and connected to the main frame, and the tractor frame/tramming unit assemblies. The main frame carries the rear thrust posts and serves as a mounting structure for both the rear trim cylinders and the conveyor lift cylinder. The front thrust posts are integral with the rotor drive gear case. The tractor frame supports the entire weight of the machine and transfers this weight to the tractor treads through bogie wheels. The weight of the rotor drive gear case, conveyor assembly and main frame is supported by the tractor frame through the front and rear trim cylinders. These cylinders provide for complete control of the cutting mechanism position regardless of the seam orientation. The thrust of the tramming mechanism is transferred to the cutting elements through the thrust posts on the rotor drive gear case and the mainframe.
The cutting unit is driven by two 448 kW continuous duty electric motors for the rotors and three 132 kW electric motors for the top and bottom cutting drum. The hydraulic system is driven by a separate 250 kW motor, which allows the miner to be positioned and trammed without sacrifice of power to the rotors, conveyor and cutter drums when mining. This independently powered hydraulic system also allows the miner to be trammed without the necessity of running the rotor motors. The conveyor chain is driven hydraulically.
The MF420 is equipped with a Top and Bottom Cutting Drum Set. The cutting drums are equipped with drum extensions to improve the manoeuvrability in backward direction. Lifting cylinders can raise and lower the top cutting drum as well as the bottom cutting drum. Both bottom and top drums are driven with a separate drive system comprising of one 132 kW motor with a gearbox for the top drum and two 132 kW motors and two gearboxes for the bottom drum. This set up has no drive shaft take up from the main gear box. It allows the machine to cut approximately 100 mm higher than the main rotors if required to follow the undulating potash seam (clay marker).
Advantages of cutter drum are:
- Sharp corner between roof & rib
- Reduces major cause of breakdown and wear (trim chain)
- Less power required – higher penetration rates
- Reduced fines
- Greater manoeuvrability to follow seams (negotiates gradient changes better)
- Slow rotation for safe pick change through separate inching drive.