Example of APC integrated directly into System 800xA for grinding and flotation optimization in minerals processing

In a typical grinding circuit ore is fed into the mills where abrasion, attrition and impact reduce its size. Usually, the grinding circuit contains at least two interconnected mills with material classifiers (e.g. cyclones) separating the fine material from the coarse (that then goes for regrinding).

The process is energy intensive with power consumption of roughly 20 to 30 MW and feed throughputs of 2,500 to 3,000 t/hr. Process variables are mill loads, motor torque and power, plus pressures and flow rates. The ground product is specified in terms of fineness.

The typical results of an APC controller are increased throughput, homogeneous product quality, reduced consumables and lower maintenance costs.

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Further, APC can be advantageously deployed in the flotation plant, where the ground ore, now in slurry form, is “washed” to separate valuable minerals from waste. The goal is maximum production or maximum yield at a given concentrate quality.

APC performs timely adjustments to froth levels, air flows and reagents leading to process stabilization, minimized reagents and increased recovery.

• Particle size controlled
• Mill loads stabilized (standard deviation decreased by 79%)
• Autopilot for operators
• No constraint violations with respect to power, torque, mill load

^{*Results gathered over a six month evaluation}

• Recovery increased by 1%
• Reduction of variability in product grade
• Increased stability of froth levels and reagent consumption

^{*Results gathered over a two month evaluation}