Q. What are the different parts of a coal MINEMESH
A. The coal MINEMESH® module consists of three key sections: the strap section, the central scat (rock) retention section and the bent sections along the outer edges of the mesh.
Q. What does the strap section do?
A. Over time the strap section has replaced the previously used “W” strap. The new strap section, utilizing OneSteel Reinforcing’s patented double wire technology and prescribed spacing, is lighter and less cumbersome than the “W” strap and is, therefore, a more effective and efficient strata control option. The strap section is positioned where the roof bolts pass through the mesh module and physically retains it to the roof of the roadway. The double wires used in the strap section increases the tensile and shear strengths required in the bolting area. The extra steel in the strap section reduces the opportunity for the plates, used with the roof bolts, to shear the wire and allows more torque to be applied to the bolt.
Q. What does the rock retention section do?
A. This is the main body of the module and is designed to capture and contain any small pieces of loose rock (scat) which can fall or be ejected from between the roof bolts. The action of restraining and maintaining support to the unraveling rock means that the mesh can contribute to the confining of the layers beyond the loose rock in the roof of the roadway.
Q. Why are mesh modules bent?
A. Roof mesh modules are bent at each edge in the reverse direction to each other in order to increase the rigidity of the module. This reduction in flex assists in making easier manual handling and installation of the modules.
Q. Why do the wire diameters vary?
A. Variations in wire diameter (5.0mm, 5.6mm and 7.0mm) are mainly a function of the strata conditions within a particular mine or area of a mine. MINEMESH® is available for light, medium and heavy-duty strata control applications depending on the ground conditions prevailing in the roof. Where roof bolts required more torque to be applied to reinforce the roof then a heavier wire
(7.0mm) could be justified in the strap section. Also, as the load comes onto the roof after the
longwall has passed then the extra strength gained through a larger diameter wire could assist in preventing the plate shearing the wire.
Q. Why do the apertures vary?
A. Traditionally the apertures have been 100mm x 100mm in the scat retention section of the module. However, in mines with more competent strata conditions a 150mm x 100mm aperture can been used to reduce the weight of the module and help make manual handling and installation easier.
Q. What are the benefits of galvanizing?
A. The major benefit of galvanizing is to increase the corrosion resistance of the wire. Corrosion of mesh can be an issue in underground mines. The wire is typically not thick and, therefore, once corrosion starts to attack the wire and welds, the load bearing capacity becomes unknown. This can lead to problems in older sections of the mine where the underground water/moisture has had time to attack the wire and welds leading to accelerated corrosion of the ground support system. Corrosion of the wire can be decreased by the use of coatings such as galvanizing.
Q. Does MINEMESH® comply with relevant Australian Standards?
A. There are no Australian Standards for MINEMESH®. However the MINEMESH® supplied by OneSteel Reinforcing for use in coal mines is manufactured under strict guidelines that meet and exceed the requirements of both domestic and international mining markets.
For more information see MINEMESH Quality Assurance Certificate.
Q. What tagging and accountability/traceability procedures do you have in place?
A. Each pack of mesh sent to a customer is tagged. The key information on this tag is the date, time, location of manufacture as well as the product code. With this information OneSteel Reinforcing, as part of its Quality Assurance program, can review test results of the batch in question and identify the source of the wire. This information is vital in trouble shooting and process improvement.