Nickel Ore Moisture Control  

The MOISTSCAN MA-500  has proven to be very compatible with applications within the Nickel Industry. This analyser was installed at BHP Billiton’s Yabulu Refinery at Townsville, Queensland.

Typically the MOISTSCAN MA-500 obtains an instrument precision of 0.7% for products which have a moisture range of 25% - 40%. 

The main applications for the MA-500 include,
De-watering circuits such as for the input to kiln dryers
Plant feedback by analysing the output of the kiln dryer
ROM applications for metallurgical accounting
Loading Ports and train load outs for commercial and contractual purposes.
Measurement of nickel carbonate within the process

Clients involved with the MOISTSCAN MA-500 currently include, SLN Nickel (New Caledonia) , Votorantin Metatis (Brazil) and BHP Billiton.  The QNI staff use the analyser constantly for metallurgical accounting.

Queensland Nickel Plant's use of Moistscan Microwave technology.
One of the most recent examples of Moistscan accuracy was the analysis of its performance on site at Queensland Nickel Pty Ltd. (QNI)
Located in Yabulu near Townsville, QNI is a subsidiary of BHP Billiton Ltd and refines laterite nickel ore to a range of nickel products as well as producing cobalt. The annual production capacity is 30,000 tonnes of nickel and 2,000 tonnes of cobalt. Ore is received at Townsville port, transported by conveyor to the refinery and is stored on a 800 000 tonne stockpile from which it is reclaimed and then dried for further processing.

It is important the ore is dried to a consistent moisture level as variations can lead to process instability and unnecessary losses.
there is also a need for moisture measurement to obtain a mass balance and for metallurgical accounting purposes.
The stockpiles are open to the weather and hence variation in moisture content on receival at the drier.
Several technologies have been tried at the refinery to monitor moisture content including Near Infrared (NIR).
The ores are very difficult to handle, having a claylike texture resulting in an inconsistent feeding system onto the belt which in turn causes continual changes in the ore profile.
This results in significant surging of the material.
The nickel ore also tends to agglomerate into lumps when wet and this tendency is heightened by increased moisture content.

The largest rock size is generally less than 150mm with particles down to 50 microns.
The bulk density of the nickel ore is generally 1.4 to 1.7, however extreme range is .9 to 1.8. 

Ore travelling on the conveyor belt is not necessarily homogenous; segregation of particle sizes does occur with smaller particles, of higher specific gravity, forcing the larger particles to rise to the top when transported.

A typical laterite nickel ore analysis is 1.5%Ni, 0.18% Co, 40% Fe, 3.5% Mg, 1%Mn

APPLICATION DETAILS
The moisture measurement range is given as: 
Normal Range : 29% to 37%
Extreme Range : 25% to 41%
Average Value : 35%
The bed depth of the ore was typically 80 to 300mm with an extreme range of 50 to 400mm. The temperature of the material was ambient but MoistScan was installed without protection from sun or rain and had to withstand typical north Queensland conditions. the conveyor the system was installed on was 900mm wide and 910 metres long with a belt speed of 3.28metres/sec.

RESULTS
The MoistScan performance was verified by taking two samples from the moving conveyor and analysing each sample in different laboratories.
This sample was then compared with the one minute rolling average of the MoistScan analyser.
The conclusion of the sample program was that the MoistScan displayed an equivalent accuracy to that of either laboratory.
The microwave technique has been shown to be precise and reliable in providing moisture measurements in a number of other applications.

Nickel Applications for moisture analysis  ENQUIRE ON-LINE