{"id":12695,"date":"2022-09-27T08:00:18","date_gmt":"2022-09-27T08:00:18","guid":{"rendered":"https:\/\/admin.acceleratingscience.com\/mining\/?p=12695"},"modified":"2022-09-19T12:17:34","modified_gmt":"2022-09-19T12:17:34","slug":"tramp-metal-detection","status":"publish","type":"post","link":"https:\/\/www.thermofisher.com\/blog\/mining\/tramp-metal-detection\/","title":{"rendered":"Tramp Metal Detection"},"content":{"rendered":"

\"BulldozerEditor’s Note: This article is based on our free webcast \u201cTramp Metal detection as a crucial tool for preventing loss in cement production\u201d<\/a> delivered by Cesare Riva, expert on cross-belt analyzers, mineral products, and bulk weighing and monitoring solutions.<\/em><\/p>\n

What is Tramp Metal?<\/h1>\n

\u201cTramp metal\u201d refers to any metallic scrap that accidentally finds its way onto conveyors and into bulk material during the cement manufacturing process. Tramp metal can originate from a variety of different sources, consisting of bucket teeth, manganese steel mantles, bore crowns, bar scrap, chains, and various types of tools.<\/p>\n

In the cement industry, tramp metal is the arch enemy of the crusher. In fact, it presents a significant risk of blocking and damaging crushers, shredders, belt-conveyors and other processing equipment. As a result, a tramp metal detection is essential in order to ensure continuity of operation and protecting the safety of workers.<\/p>\n

Tramp Metal Detection<\/h1>\n

Tramp metal detection<\/a> is carried out by metal detectors installed directly on convey belt lines. Tramp metal detection is the only reliable and cost-effective method of protecting expensive crushers, shredders, conveyor belts and in-line weighing, sampling and monitoring equipment. By detecting the presence of metal objects that conventional magnets may miss, tramp metal detection provides reliable protection to your processing equipment. Investing in a tramp metal detection system is an essential part of protecting cement production<\/a> operations from costly production delays and safety risks.<\/p>\n

During tramp metal detection, solid material passes across a metal detector. When tramp metal is detected, it can either be removed manually or automatically. With manual removal, tramp metal detection triggers an alarm relay and stop the belt \u2013 this allows a safe manual removal of the tramp metal to prevent it from entering the downstream process. In automatic removal, tramp metal detection activates a bypass chute to automatically reject the tramp without stopping the belt.<\/p>\n

Tramp Metal Detection Technologies<\/h1>\n

There are two main technologies for tramp metal detection<\/a>: inductance systems and eddy current systems. The most effective for tramp metal detection in cement minin<\/a>g and other bulk industries is the eddy current system.<\/p>\n

Inductance-Type Tramp Metal Detection <\/strong><\/p>\n

Inductance-type tramp metal detection system, make use of an oscillating magnetic field produced by a wire coil. When a conductive or magnetic piece of tramp metal passes over the coil, the oscillations change. This change is detected by the electronics and an alarm is tripped.<\/p>\n

There are some advantages to induction-type tramp metal detection: in particular, they tend to be more sensitive than eddy current-type systems. However, there are also some limitations. First, in order to be detected, the tramp metal must be more conductive than the material it’s buried in. In addition, Changes in the belt loading, or the presence of water, can cause false positives. Crucially, non-conductive ore, such as manganese, can\u2019t be detected using this type of tramp metal detection system.<\/p>\n

Eddy Current-Type Tramp Metal Detection<\/strong><\/p>\n

In eddy current-type tramp metal detection system, a pulsed current is applied to a coil, which induces a primary magnetic field around it. When tramp material moves through the field, the primary field induces eddy currents in the tramp metal. The eddy currents induce their own secondary magnetic fields around these pieces of tramp metal.<\/p>\n

These secondary magnetic fields generated by metallic materials on the conveyor can be differentiated by observing the rate at which they decay once the primary field is switched off. This decay time is a signature of the material, be it ore or tramp metal. Electronics in the detector can discern the difference in the signal between valuable material and tramp by activating its measuring window only after the magnetic field from the material has decayed, but before the magnetic field from the tramp metal has ended.<\/p>\n

One of the primary advantages of this type of tramp metal detection is that it can be used to detect ferrous and non-ferrous metals alike, such as manganese steel or copper. Eddy current tramp metal detection systems also completely ignore water, and changes in belt loading have minimal effects. The disadvantage, however, is limited range: the distance between the tramp and the coil is relevant and maybe be a disadvantage in certain applications.<\/p>\n

Choosing the Most Effective Tramp Metal Detection System<\/h1>\n

While there is no one-size-fits-all solution for tramp detectors<\/a>, there are several basic features<\/strong> you should look for.2<\/sup><\/p>\n