NEW CONTRIBUTIONS TO ENERGY SAVINGS IN THE TRANSPORT OF MINERALS BY CONVEYOR BELTS

Born during the crisis of 1982, TTM (Technology in Mineral Transportation) has been linked from its origins to the efficient use of resources to provide transport systems of mineral. Today, with more than 430 employees and branches from Lima, Peru, Bolivia and across the North and Central zone of Chile, TTM is focused, with its supplier partners in developing technology to target the energy efficiency of material transport systems.

“Our concern now is to make a contribution to energy consumption savings in the mining industry,” explains Horacio Undurraga, director and founder of TTM.

“This is actually done through efficiency in the transport and through various scientific researches in which we’ve been able to improve to achieve significant energy savings,” adds Undurraga.

The resistances that must be overcome to move the material are divided into primary and secondary. Part of phenomena that produce secondary resistance on the belt are at haulage points or tail resistors produced by friction due to the acceleration of the load, the skirtboards, scrapers; and in the discharge or head, by the scrapers, but they only have influence in the case of short belts. In the long belts or Overlands, these secondary resistances are negligible when considered part of the total resistance and in this case are only considered for the purpose of calculating primary resistances.

The primary resistances include the bending of the belt and the influence of the weight of the material that goes up and down between the idler stations; rolling resistance on each idler; channeling resistance, misalignment and dirt; and indentation resistance, which is the asymmetric deformation of the belt in contact with each idler.

“We have targeted two areas that have allowed us to achieve significant savings in the process of material transportation. The first has to do with the introduction of idlers with low rolling resistance, by our supplier K√ľpper, allowing the passage of load using less energy to overcome this resistance. Each standard idler used to this date, with 12 Newton of rolling resistance measured and a shooting speed of 6 meters per second, consuming 72 watts, and today the same work is performed with low resistance idlers developed by K√ľpper, with only 3 Newton of rolling resistance, with barely 18 watts at the same speed. For example in a belt of 10 thousand idlers (3.000 stations spaced at 1.5 meters), with a consumption of 720 kilowatts for this item was passed to 180 kilowatts, with an actual saving of 540 kilowatts, “explains the director of TTM.

 

Indentation Resistance

At the same time their strategic partner Phoenix commissioned a study conducted at the University of Hannover in Germany, to study and measure the resistance of indentation, making a complete conveyor especially for laboratory analysis, but under various conditions of mining operation. “In that study it was calculated that 62% of the indentation resistance is caused by the elastic deformation of the belt as it passes with load over each idler. It is because of the asymmetric deformation occurring on the opposite side of the passing of the load. And it is force acting against the movement of the belt, “explains Horacio Undurraga.

With the survey results in hand, Phoenix changes the composition of the elements of the conveyor belt, producing a new product: the EOB straps (and following the conclusions of this study also finished producing what is now the standard DIN 22123 ).

“The change in composition of the elements of the belt was vital to cause less resistance to indentation, which resulted in higher energy savings. The results were very good, because a 20% decrease in energy consumption was achieved in horizontal straps. To give an example, if before with one belt we used a 1MW engine, today it works with one of 800 KW, or it can, with even better results, increase the load carried with the same drive system “says the founder of TTM.

The study was checked on site in a real operation, together with RWE in a coal mine near Cologne, Germany, and the field results were very consistent to those laboratory tests yielded with the test machine of ITA Hannover.

“It’s always good to remember that energy savings also depend on the good alignment of the belt, how it is loaded, the tension, the distance between idler stations and what also has great influence is the belt cleanliness”, concludes the executive.

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