Comminution Process: How energy-savings can be increased in mining

Mining is known for its long-lasting and resource consuming processes which ultimately lead to an increase in cost and consumption of energy. For instance, the Comminution process, the combination of grinding and crushing, consumes approximately 3% of the total global electricity. In addition, the Coalition for Energy Efficient Comminution (CEEC) states that the process is responsible for 10% production costs.

Designs

In order to control the energy consumption, different comminution circuit designs undergo a hit and trial approach since there is no standard design that fits every circuit. Samples of the ore are collected and their characteristics are studied comprehensively. The results of this analysis are processed through various comminution designs until the energy savings are maximized.

Circuit designers

Designers have to choose the appropriate type of mill (solid material crushing device) or design depending upon the characteristics of ore, applications, operation size, site location, environmental (natural factors), and all round company requirements. For high moisture applications, the design is made to suit autogenous or semi autogenous grinding. Similarly, in case of solid rock applications, designers prefer a High-Pressure Grinding Roll (HPGR) circuit since crushing is of upstream nature.

Equipment size and energy saving

Since the last three decades, the underlying notion associated with energy saving has promoted the use of big machinery. However, this cannot be considered as a universal choice for sites. Reduction ratio of comminution machinery is directly and inversely proportional to the size and energy conservation respectively.

Designers often encounter the dilemma of one large mill or two small ones. While former supports cost reduction due to less equipment, manpower, space, and material, latter ensures output even if one of the mills encounters a functioning issue. Weighing the pros and cons, the concept of large mill was preferred and consequently, semi autogenous grinding gained traction. However, it wasn’t until a few years ago that F80 to P80 comminution machinery offered the benefits of both mill arrangements in one system.

This made designers assume that energy saving is not necessarily about reducing the number of grinding steps in every situation. It might be possible that the steps may increase by one, but their concise nature can prove instrumental in increasing energy conservation.  

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