At Minera Centinela, for the secondary milling operation, it is important to control the volume inside the mills. One part is occupied by balls (34-36% of the total volume), which are the milling media that produce the size reduction of the mineral fed to the mill. These 3.5 inch diameter steel balls wear out and when they reach diameters of less than 2 inches (scrap), they no longer perform their function optimally. In addition, this scrap continues to occupy space inside the mill and becomes a circulating load in the grinding-sorting circuit, generating process inefficiency as well as operational problems such as obstruction in the pulp transport system. Due to the above, scrap must be removed in order to make efficient use of the installed power, which optimizes the treatment of the ore and the quality of the flotation product by ensuring an adequate particle size distribution. Additionally, the removal of this circulating load will facilitate operational continuity by avoiding operational incidents due to obstruction problems in the pulp transport system.

It is necessary to implement a system or technology that allows the automated disposal of the scrap formed in the secondary milling circuit.

• Minimal intervention and modification of the millpulp conveying system-cyclone battery circuit, which must be adjusted to space limitations (see diagram in Annexes).
• The solution must guarantee operational continuity, i.e., the devices or components must be easy to install, access and maintain.
• A technology readiness level is required at least at the level of a prototype tested in an operational environment (TRL≥7).
• Must meet with Antofagasta Minerals’ safety standards.

A “basket” was designed with the objective of passing the mill discharge flow avoiding the scrap to pass into the conveying system that leads to the next stage. In addition, the circuit was equipped with a magnetic trommel which was removed due to operational problems caused by the magnetite content of the treated ore (4-6% magnetite).

• Utilization of maximum installed power in ball mills.
• Decrease of P80 by optimization of ball collar in secondary milling.
• Decrease in wear of components of pulp transport and impulsion systems.

• Ball mill power.
• P80 to flotation.
• Useful life of transport systems components and pulp drive systems.