Resumo

OCAMPO-RAMIREZ, Arturo et al. Mitigation of Dynamic Stresses of a Ball Mill Using Rubber Coatings. Rev Cie Téc Agr [online]. 2020, vol.29, n.4  Epub 01-Dez-2020. ISSN 2071-0054.

Ball mills are widely used in mining, agriculture and cement industries. There is little information on the design of such equipment from the structural point of view. Some of the main causes of failure are fractures of their walls, due to the impact of steel balls on their internal surfaces. Normally, they are attenuated through the use of wet milling, which acts as a shock absorber and a casing that protects the internal surfaces of the mill. However, it should be noted that this casing is not used in small mills. To avoid failure, the thickness of the mill is over-designed, increasing its cost. The design of small mills improves when considering the direct impact of the steel balls on the inner wall. This leads to the most critical condition of operation. In this work, the resulting stress field was evaluated following a couple of approaches: (I) the dynamic coefficient of impact loads was evaluated with the working energy principle and (II) a numerical analysis was performed with the Finite Elements Method. The operating parameters were calculated with the BM-Crush Program. The results showed that the cyclic stresses were close to the elastic limit. It was proposed to implement a rubber coating on the internal walls of the mill and the stress field was reduced 8.3 times, for a rubber thickness of 3 mm. In this way, a potential fatigue failure could be reduced.

Palavras-chave : Internal Wall; Load Impact; Direct Impact; Finite Elements.

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