Metso master of material handling
Upgrading a material handling system or plans to increase production requires a review of several aspects, writes Göran Persson* of Metso.
01 September 2005
Companies planning to increase production or streamline their current set-up, often begin by thinking in terms of production levels before considering material flow.
There are however many contributing factors which have to be considered when optimising a material transportation operation.
A natural starting point is to look at the speed of the conveyor belt. An increase in conveyor belt speed moves more material per hour but it will have a ‘knock on’ effect along the complete chain – from loading, over transfer points, to discharging and stocking of material.
It is also likely to result in increased wear in the chutes, generate more noise, increase dust plus general ‘wear and tear’ of the conveyors together with possible degeneration of material.
With optimisation software – from suppliers such as Metso Minerals Wear Protection and Conveying (WPC) – it is possible to find the optimum solution needed to achieve the lowest cost per tonne.
The software allows simulation of all incoming factors, such as chute design, speed of belt and material density, etc.
The key is to have the competence to balance all the factors that includes material character, such as abrasiveness, velocity of the material, material density, discharge angle, material flow/volume, chute design, wear material selection, conveyor design, dust and noise.
Belt speed
An increase in belt speed means that the material will have a higher end-velocity when it leaves the belt and consequently hit the chute at a higher level. This can create the need for a redesign of the chute and most likely require new wear material for optimum wear economy.
Wear material is determined by the impact of the material and also its abrasiveness. The other factor to be looked upon while deciding on the plates is the need for noise reduction.
One proven material which is excellent to use in many applications, is rubber-based wear-plates such as Trellex PP, SQ and PolyCer. Rubber not only has excellent characteristics against wear but also against impact and noise.
Reduced noise
Trellex rubber-based wear plates and rubber-lined trucks not only give a lower cost per tonne but can also reduce noise by up to 10-15 dB (A) and can be the difference between being allowed to operate or not, especially since there is an ever increasing demand from neighbouring residential areas to reduce noise levels from quarrying, recycling and other similar operations.
Dust control
One aspect often overlooked in the first phase is dust in the loading area – a real problem for many operations. Meeting an increased conveyor belt speed and material flow, will almost certainly require redesign of the hoods above the belt. The increased volume of moved material may not permit sufficient volume of air to pass resulting in a possible uncontrolled spread of the dust.
Spillage is yet another factor to consider. Most spillage takes place in the loading/ unloading area. Often the handled material changes speed and direction creating airborne dust. It is also important to incorporate a sealing system able to contain the fine particles so that they remain on the belt. Trellex sealing systems are designed in such a way that they do not damage the belt and are easy to adjust.
While material degeneration may not be the most common aspect to consider, in applications such as lime, it requires careful consideration. The increased velocity of the material when it hits the chute can often cause it to change shape/character.
Conveyor evaluation
The conveyor itself also needs evaluation on aspects such as belt width and speed, motor effect, dump bed, scraper placements and roller types if it is to meet the new production level. A too wide belt or too high speed gives poor utilisation of capacity and energy, while on the other hand too small a width gives overfill, spillage and lack of capacity control.
Metso has the relevant know-how and offers assistance and advice when it comes to the effect such an upgradation of the material handling system will have on other parts of the operation and, the possibility to solve the resulting criteria with the company’s large range of products.
*Göran Persson is product line manager for Metso Minerals Wear Protection and Conveying (WPC).
