Machinery and equipment in the mining industry are often in need of repair and maintenance. The harsh operating environment leads to problems such as abrasion, chemical damage, corrosion, impact and wear.
Vibrations in the mining environment can lead to equipment wear and fatigue, resulting in cracks and a loss of material integrity. Vibrations from operational equipment can cause premature failures in concrete foundations and anchoring systems. The brittle concrete can be too weak to absorb the constant impact and vibration transferred from mining equipment. Once the concrete fails, anchor bolts in the foundations loosen, further weakening the foundation.
A copper mine in Marabá, Brazil, found this to be the case with its primary crusher. The base of the primary crusher needed to be rebuilt due to damage from vibrations. The weight and size of the primary crusher further contributed to the stress on the foundations. As one of the largest copper crushers in South America, weighing 336 t, with a height of 9.5 m and width of 5.6 m, the crusher processed over 3 000 t of copper ore an hour.
The mine required a solution to rebuild the foundation and bases of the primary crusher, allowing it to withstand high dynamic and impact loads without shattering and breaking. A fast curing time was also required to ensure that the crusher could return to service as quickly as possible.
Using an impact hammer drill, the first two layers of concrete were removed to reach the steel reinforcement structure. The substrate was cleaned and degreased with solvent and compressed air was used to remove loose debris and dust. A conditioner was then applied to ensure optimal bonding between the substrate and repair materials.
Belzona 4111 (magma quartz) concrete repair and rebuild composite was used to recreate a foundation at the base of the primary crusher. The solution offers resistance to high vibrations and dynamic loads due to its mechanical strength. In addition, the composite adheres to both metal and old concrete; allowing for a homogeneous load distribution without weak spots, during the anchoring and grouting procedure and service.
The machine was re-assembled four to six hours after application and a full return to service was possible after about 16 hours.