#Industry News
Application of Level Switch in Transfer of Mine Filling Material
An environmental protection engineering company was convinced by the excellent quality of vibrating rod level switch from Jiwei and purchased Jiwei Tube-11 for one kilometer deep well test project.
In deep well mining, how to transfer mine filling material and support materials in a safe, efficient and environmentally friendly way is a difficult question that mining enterprises are facing. The filling material is generally a fine powder which often solidifies quickly when it is stirred with water. There are two traditional methods for transferring filling materials. One is with mining trucks and another is with a transfer belt. Both methods have the problems of longer transportation time and too many links in the transfer path. In comparison, pipeline transfer uses compressed air as a power to fulfill one-stop automatic transportation of filling materials from ground to underground mine through an intelligent control system so that the problems with traditional methods will be effectively solved. Intelligent pipeline transportation systems mainly include ground terminal, transit station, working station, transfer pipeline and communication system. The stable operation of the system is relying on the accurate material level measurement. We need to figure out where the level switch will be applied in the filling material transfer process, what are the special requirements for the level switch in the underground environment, and how we can make the right choice for the level switch.
1. Applications of level switch in pipeline transportation of mine filling material.
Ground terminal usually includes several vertical silos and transit silos that are ten meters or tens of meters high. It functions as a ground material storage terminal and control center. Transit station is located between the ground terminal and underground working station and should have a function of automatic feeding for empty silos and automatic stop when the silo is full. When the working station sends signal and demand filling materials, the transit station will automatically transfer the filling material to the working station. The working station mainly fulfills the function of automatic material proportioning and filling. Monitoring pipeline status involves the detection of pressure, flow rate and material level. Therefore, detection and control of the material level is throughout the entire filling material conveying process.
2. Technical requirements for level switches
High reliability, easy installation, and maintenance-free are very important features of an instrument. Among them, high reliability is particularly important. High reliability of a level switch means no false alarm and with strong interference resistance. We know that powdery material has a strong hygroscopicity in humid air. Therefore, the level switch must have a certain tolerance to material buildup to avoid fault caused by slight material buildup. In the ground terminal, a level switch is used for high-level interlocking alarms. Tolerance to material buildup and false alarm are main concerns here. While in the underground transit station and working station, there are different concerns. Besides high reliability, underground safety requirements must also be satisfied. Because there are flammable and explosive gases in the underground mine, the electric circuit must be designed for intrinsic safety explosion protection. In addition, the selected material for the external housing of the instrument has to meet specific requirements in order to avoid sparks generated from collision between foreign objects and external housing of the instrument to ignite flammable and explosive gases in the mine. According to the provisions of GB3836.1, for material used for external housing of an electronic equipment in category I, EPLMa or Mb grade, its content in mass percentage should not exceed: a) 15% aluminum, magnesium, titanium, zirconium; b) 7.5% magnesium, titanium , Zirconium. And the material should also satisfy a specified friction spark test. Generally speaking, stainless steel, copper, and cast iron can all meet the above requirements.
3. Performance comparison of level switch products and level switch selection
It is obvious to see that a double rod vibrating level switch, which is designed with nested internal and external vibrating rod, has more advantages under mining working conditions than other level switches: maintenance-free, strong resistance to material buildup, easy installation and safer to operate.
After careful comparison between different brands and different types of level switches at home and abroad, an environmental protection engineering company in Beijing was convinced by the excellent quality of vibrating rod level switch from Jiwei and purchased Jiwei Tube-11 for a one kilometer deep well test project in Tianjin.
Sales engineer in Jiwei communicated with the customer and helped the customer place the order for Jiwei Tube-11ICXXWXML with Intrinsic Safety explosion protection. Tube-11 vibrating rod level switch is the first domestic double rod vibrating level switch. The probe is designed with a unique nest configured in the inner and outer double tube. The resonance frequency of the inner and outer vibrating tubes is precisely adjusted to the same value to reach complete resonance so that the instrument reaches extremely high detection sensitivity and reliability. The measurable medium density can be as low as 0.02g/cm³. The ingress protection level of the instrument reaches to IP66 /IP67. Signal output is selected as a two-wire system. The external housing is made of T3 copper.
The instrument has also been successfully certified for coal mine safety by the Safety Supervision Bureau China. 24 vibrating rod level switches from Jiwei have been working stably and reliably in the first phase of the project since they were put into use in 2018 and Jiwei Tube-11 double rod vibrating level switch has been well evaluated by the user.
