Presenting at the Emerson Exchange EMEA 2024, Juan Rodriguez, process control supervisor at Poderosa Mining Company, outlined how the implementation of magnetic flow meters has helped to boost energy efficiency and gold recovery.
Poderosa Mining is a gold processing company located in the province of Pataz, almost 320 km from the city of Trujillo, in Peru. At the company’s Maranon and Santa Maria plants, gold is recovered utilizing the cyanide leaching or direct cyanidation process. The total processing capacity of the two plants is 980 tons per day.
In the mining industry, there are several challenges related to the milling process. These include optimizing the mass balance of the circulating load, increasing worker safety, reducing energy use and increasing recovery. Within milling operations at the two processing plants, manual measurements and calculations were being performed that prevented optimal cyanidation that would increase gold recovery and reduce energy costs. Performing mass balance analysis of the circulating load was very time-consuming, taking over a week to perform calculations. As a result, the ratio of fine material to coarse material returned to the mill was outside of the accepted tolerance values. This variability led to significant rework by the hydrocyclones, increasing energy costs, and reduced recovery in the flotation cells process.
Due to the nature of this application, safety and environmental risks are an issue. Performing manual pH and level measurements placed personnel near cyanide, creating an increased safety risk. Spills and gases produced during the cyanide hydrolyzation process are dangerous to workers. It was therefore essential to maintain the correct pH to decrease the production of hydrogen cyanide gas.
The milling application is particularly challenging for measurement instrumentation. Measuring flow is challenging due to the high solids content. Manual level measurements introduced variability and human error, while an irregular surface could cause an issue for automated measurement technology, and constant vibration could impact device reliability. The performance of pH sensors is impacted by coating, and their lifespan is compromised by the abrasive chemicals.
Poderosa Mining Company turned to Emerson for support and it recommended its magnetic flow and density meter, radar level transmitter and pH sensor and monitoring system. Rosemount™ MS magnetic flow meters for slurry applications were installed in the feeding pipelines to the hydrocyclones, which enable accurate in-line density and flow measurements. The sensors provided a real-time response to flow rate changes and reduced measurement variability, even in high solid content applications such as this. As a result, hydrocyclone rework has been minimized.
Emerson’s Rosemount MS magnetic flow meter for slurry applications has enabled real-time mass balance calculations.
A Rosemount 5408 Non-contacting Radar Level Transmitter was installed to replace manual measurements, minimizing personnel exposure to safety hazards and increasing measurement accuracy. The advanced radar technology easily copes with irregular surfaces and its robust design can handle the high levels of vibration. Remote configuration capability has further limited workers’ exposure to risk. Emerson’s Rosemount 396 Submersion/Insertion pH Sensor and the Rosemount 1056 Intelligent Four-wire Transmitter were also deployed. The 396 sensor is ideal for installation in harsh, dirty and abrasive applications. Sensor maintenance is minimized due to TUpH reference technology, which ensures a steady pH signal, even when the sensor is coated. Sensor life is maximized due to a helical reference pathway which hinders reference poisoning.
A Rosemount 5408 Level Transmitter installed at the Poderosa Mining Company’s Maranon plant.
The advanced measurement devices have helped to improve safety, operational efficiency, energy conservation and gold recovery. Real-time mass balance calculations are now possible. This has led to a 15% improvement in the circulating load ratio. A 0.5% increase in gold recovery can be directly related to the project. In terms of safety, exposure of workers to pulp materials has been reduced by 50%, and there have been zero spills or cyanide hydrolyzation since implementation.
