As demand for nickel skyrockets in the quest for a clean-energy future, laterite ores are becoming an increasingly important source of nickel.
One of the major challenges presented by laterite ores, however, is their high moisture content, which, depending on the method of processing chosen, almost always requires removal. For this, the industry relies on rotary dryers.
Here’s a look at how rotary dryers are supporting the growing use of laterite ores.
The Laterite Ore Boom
As we highlighted not long ago in Processing of Nickel Laterite Ores on the Rise, sulfide ore resources – the primary source of the world’s nickel up to this point – have been declining as existing high-grade sources become tapped out and new discoveries wane, leaving only laterites behind.
The situation has only tightened since, as demand for nickel used in electric vehicle batteries, stainless steel, and renewable energy technologies has continued to rise ever higher.
The situation has become so dire, in fact, that some producers have even begun investigating ways to produce class 1 nickel from laterite ores, which historically have served only as an economically viable source of class 2 nickel, due to the highly complex nature of converting them to class 1.
The Need for Nickel Laterite Dryers
While drying is a common first step in many mineral processing operations, it is essential when it comes to laterites, which are typically surface mined in the tropics and can contain up to 30% moisture.¹
This high moisture content gives laterites a wet and sticky quality, which makes further processing, and even simple handling, difficult for most technologies and equipment used in beneficiation. Processing the material as-is would likely clog equipment, inhibit proper material transfer, and present an array of other processing issues associated with sticky materials.
To avoid such challenges, a drying step is therefore critical, removing the free moisture so that nickel can be beneficiated from the ore.
Drying, which may also be referred to as dewatering in this context, typically brings the moisture content down to around 5-8%, though in some cases it may be as high as 20%. Care must be taken to not overdry the ore, as this will cause it to become dusty.
In theory, drying could be carried out in the downstream pre-reduction kilns, but this approach would be highly inefficient, and as such, a separate dryer is employed.
Why Rotary Dryers for Nickel Laterites?
The industry’s choice of equipment for carrying out laterite drying is the rotary dryer.
While little information is available on the preference, it is likely due to the reasons for which rotary dryers have become the equipment of choice in other areas of the mining sector: a high-capacity throughput and heavy-duty build.
Rotary dryers can process up to 300 TPH in some cases and are known for their rugged design and construction. They also offer a number of other advantages that bode well for the mining industry:
- Simple operation
- Long-term reliability
- Well-established
- Highly customizable design
- Tolerant of variation in feedstock
Maximizing Nickel Laterites Through Dust Recovery
One important thing to note about the drying process, is that some nickel dust and fines become entrained in the process gas, exiting the system through the exhaust handling equipment.
Historically, these fines, along with other dusts generated throughout laterite ore processing and handling, have been collected and deposited into tailing heaps as a means of waste management. But as nickel becomes more valuable, and producers look to create a closed-loop business model, these fines are seeing a new life through pelletizing; by pelletizing the fines into large agglomerates, the dust and fines can be used as charge in the blast furnace, allowing the nickel to be recovered.
This process, along with drying, can be developed through testing in our Innovation Center, where we have a variety of batch- and pilot-scale equipment used to assess feasibility and gather process data for scale-up.
Conclusion
As nickel continues to play a greater role in meeting future sustainability goals while sulfide ore sources dwindle, laterite ores will increasingly be used to satiate nickel demand. The wet and sticky nature of laterites, however, requires the ore to be dried before it can move on to further processing in most cases, and for this, the rotary dryer is the equipment of choice.
FEECO has long been a preferred provider of custom rotary dryers for the mining industry. Our dryers are engineered around the specific demands of the intended application. We also offer a comprehensive rotary dryer parts and service program for keeping rotary dryers running their best. For more information on our rotary dryers or supporting services, contact us today!