According to the relative position of the shaft and the ore body, there are several development methods.
First, the lower shaft development method
Figure 6-8 shows the lower shaft development method, V1, V2, and V3 indicate steeply inclined ore bodies. The shaft is drilled outside the rock movement belt of the ore body, and the stone gate reaches the vein. This method of exploitation is the most widely used in domestic metal ore.
The biggest advantage of the downhole shaft development method is that the wellbore protection conditions are good and there is no need to leave a security pillar. The disadvantage is that the length of the stone gate lengthens as the depth of mining increases. When the inclination of the ore body becomes small, the lower stone door is particularly long. Therefore, the lower shaft development method is applicable to steeply inclined ore bodies buried below the ground level. It is more advantageous when the inclination angle of the ore body is greater than 75°.
Second, the upper shaft development method
Figure 6-9 shows the upper shaft shaft development method. The shaft is drilled outside the rock movement belt on the ore body, and the Shimen access to the ore body is drilled. This kind of development method has serious shortcomings compared with the lower shaft development method. Mainly in the upper stage to be excavated: entering a long stone gate, long construction time, large investment in the initial stage of infrastructure construction, only considered under the following special conditions.
(1) According to the topographical conditions of the ground, the lower part of the ore body is Lushan, and the top plate is flat, and the upper shaft is used, and the length of the wellbore is small;
(2) The mining ground terrain conditions and internal and external transport links mining, mineral processing plants and tailings should only be arranged on the disc in the direction of the ore body, when using the disc and the vertical transport route can be shortened, thereby reducing the laying Investment and transportation costs of transport routes;
(3) The geological conditions of the lower plate are complex, and it is not possible to avoid the fracture zone or the sand layer and the aquifer with a large amount of water inflow. Because it is very difficult to dig into the wellbore under such conditions.
Third, the wing shaft development method
Figure 6-10 shows the flank shaft development method, the biggest feature of which is that the wellbore is placed on the side of the ore body. When using this method of development, roadway tunneling and downhole transportation can only be one-way, so the tunneling speed is limited. Generally used under the following conditions:
(1) The top and bottom plate topography and rock formation conditions are not conducive to the arrangement of the wellbore, and the ore body has suitable industrial sites on the flank, and the selection plant and the tailings reservoir are arranged on the side of the ore body. At this time, the flank shaft is used to make the direction of underground and ground transportation consistent;
(2) The inclination of the ore body is relatively slow, and the stone door is long when the shaft is arranged on the lower plate or the upper plate;
(3) The length of the ore body along the strike is small, the tunneling time of the roadway is not long, and the transportation cost is not large.
Iron-based alloy powder is commonly used in plasma transfer arc welding (PTAW) due to its excellent mechanical properties and high resistance to corrosion and heat. This type of powder is typically composed of iron as the base metal, along with various alloying elements such as nickel, chromium, molybdenum, and tungsten.
The specific composition of the iron-based alloy powder may vary depending on the desired properties and application requirements. For example, adding nickel can increase the strength and toughness of the weld, while chromium enhances the corrosion resistance. Molybdenum and tungsten are often added to improve the high-temperature strength and creep resistance of the weld.
Iron-based alloy powders for PTAW are available in various particle sizes, typically ranging from a few micrometers to several hundred micrometers. The powder is usually fed into the plasma arc through a powder feeder, which ensures a controlled and consistent supply of powder during the welding process.
During PTAW, the powder is melted and deposited onto the workpiece, forming a weld bead. The high energy plasma arc provides the heat necessary to melt the powder and the base metal, creating a strong and durable weld joint.
Overall, iron-based alloy powder for plasma transfer arc welding offers excellent weldability, high mechanical properties, and resistance to corrosion and heat, making it suitable for a wide range of applications in industries such as aerospace, automotive, and power generation.
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