Belt Conveyor weightometers are required to accurately weight and chart the tonnage throughput. An operator is able to catch many problems that are developing simply by watching the tonnage. A drop or increase in tonnage can indicate something going wrong .within the system.
MAGNETS, These capture what is known as “TRAMP METAL”. This is metal that has gotten into the ore flow and could cause belt damage or plugged equipment.
And METAL DETECTORS, Usually designed to work with a magnet. The best metal detector for gold will indicate the presence of non-magnetic metal and metal that escaped the magnets pull.
The metal detector requires very little supervision, outside of testing it periodically to ensure that it is working properly. The weightometer and the magnet on the other hand must be checked quite often to ensure that they are clean. 
The magnet may become over loaded with metal to the point of not being able to lift any more. Also, depending on circumstance of course, it is possible for large rock to come into contact with the magnet and scrub off any of the trapped metal. A build-up of rock on the weightometer can be much more serious. To understand it is necessary to understand how a weightometer works mechanically. The weight-o-meter has a floating, or if you prefer a swing frame. When the ore travels over this frame it depresses it, the farther down it is pushed the higher the tonnage. The problem comes in when a small rock becomes lodged under this frame preventing it from being depressed. The readout from the weightometer will indicate a lower tonnage than it really is. The operator, or if it is automatic equipment, will adjust the tonnage to compensate for the false lower reading. Unless the operator is on his toes the result will be a very badly over loaded circuit and possibly a lot of down time before the equipment is running again.
Weightometer
The Weightometer is ingeniously designed to perform the function of continuously weighing moving loads by mechanically multiplying together two variable quantities and totalizing the successive products into a continuous reading.
These variable quantities consist of—first, the ever varying load on the conveyor which is often subject to extreme and very rapid fluctuations, and second, the slightly varying speed of the conveyor belt. The speed of any conveyor, while usually considered as constant, in reality varies slightly with the load. In continuous weighing, unless both conditions are taken into consideration, any final results will be erroneous.
The Weightometer integrates both variables perfectly because the integrator registering disc instantaneously reacts to variations of, and corresponds at all time to, the true position of the scale beam; also, the true speed of the conveyor is at all times transmitted to the integrator belt. For these reasons the remarkable accuracy of weighing with the Weightometer is consistent and assured.
Each Weightometer is carefully designed and built for the exact service intended, and for the conveyor upon which it must operate. However, the unit is applicable to all conditions and services and can be designed for use, not only upon belts, but upon bucket and pan conveyors as well. Thus, it is generally suitable to any size, type, inclination, capacity, and speed compatible with good conveyor practice.
The resulting weights in every case may be indicated and totalized in short tons, long tons, metric tons, barrels, or any other unit required by the customer.
Weightometers are in use on 12″ belts handling but a few tons per day, on intermediate size belts, and on 60″ belts carrying 2,400 tons per hour, or two-thirds of a ton per second. Any tonnage carried on a belt conveyor may be weighed with a Weightometer.
Its basic design is one of maximum flexibility, thus any Weightometer can easily be converted from its original load capacity to another capacity or from one conveyor belt size to another belt size at a minimum of trouble and expense. This is a valuable feature because of the permanence of the Weightometer. Some Weightometers have weighed over 40,000,000 tons of material and continue in excellent operating condition with accuracy of performance unimpaired.
Where are belt weightometers positioned in a conveyor belt: On a flat horizontal section is where to best place your weight scale.