en.Wedoany.com Reported - Brazilian mining company Usiminas (Mineração Usiminas) has improved circuit stability and productivity, and reduced unit energy consumption by over 5% after introducing an Advanced Process Control (APC) system in the ball mills of its iron ore beneficiation plant.

The grinding process accounts for a significant portion of energy consumption in iron ore beneficiation plants, directly impacting product quality and production costs. APC, as a technical tool for reducing variability and improving efficiency, is considered a viable solution for optimizing mineral processing parameters and enhancing operational stability.

Before the APC system was introduced, the Usiminas beneficiation plant experienced several abnormal operating conditions. The circulating load reached up to 520%, and the hydrocyclone bypass was 72.5%, referring to the amount of fine particles returned to the ball mill instead of entering the grinding circuit product, resulting in extremely low circuit classification efficiency. Additionally, there was a lack of proper control over slurry density, with water addition adjusted only based on the sump level, ignoring the density parameter. The sump level was set at 80% through water addition, conflicting with the centrifugal pump speed, causing the pump to operate continuously at full speed and failing to achieve the required pressure and density for feeding the hydrocyclones.

This study aimed to quantify operational improvements after APC system implementation, based on a 67-day on/off test evaluation. The dataset was divided according to different operating scenarios and analyzed through statistical tests. Results showed that, under the most favorable scenario, the variability of hydrocyclone feed slurry density was reduced by up to 63%. The average circuit ore throughput increased from 541 tons per hour to 571 tons per hour, with unit energy consumption reduced by over 5%. Slurry overflow events decreased, reflecting improved system operational stability and overall efficiency. Under stable operating conditions, the average increase was approximately 5.6%, demonstrating the system's ability to optimize feed rate under stable conditions.

Usiminas Mining Company was established in 2010, initially focusing on meeting internal demand before expanding its operations. It has since become one of the five largest mining companies in Brazil, supplying iron ore to both domestic and international markets.