Andrew Howard

The rheological behavior of laterite ores greatly influences the viability of any project involving these raw materials. I'm not a specialist in Ni-Co processing but some of the challenges relating to processing of laterite ores that can be attributed to rheology are flowability across long distance pipeline transport, liquid-solid separation processes, indirect heat
exchange processes and high temperature sulphuric acid leaching.
Some of the means used to control the flowability of these slurries include ore blending, optimizing the salinity of the process water, controlled dilution during preheating and the use of rheological additives. I would think process control around slurry transport and heat exchangers will also be vitally important in managing the challenges around rheology.

One of the factors that affects the motor’s ability to dissipate heat is the density of the surrounding air. With higher air density, more heat can be transferred. Generally the density of air at a specific location is very constant, but air density does vary with elevation; thus, when motors are installed at locations where the elevation is substantially above sea level, consideration must be given to this factor. Generally HP derating factors are applied to the motors based on altitude of where it is to be installed.

Standard motors will operate successfully within their normal temperature rating at elevations up to 1000 meters above sea level. When motors are to be operated above this altitude, the motor design should be checked for its suitability at the required elevation. 

The structure design should allow for the following.

• Easy stair access to each level for easy maintenance.
• It should provide access to both sides of the take-away conveyor. 
• Braces and structures must be kept away from equipment service and maintenance areas.
• The selection of the types of flooring in a crushing plant is always controversial and comes down to site preference and economics. Checker plate flooring allows for easier clean-up and does not allow for smaller rocks or spillage to any floors below.

The structural costs for fine crushing circuits are generally high. Hence it is really important to select the most economical structure for the support of the crusher and the ancilliary enquipments. But most importantly, it is important to adhere to the design parameters and standards of the overall plant.

It'll be nice to have ability to invite colleagues from within the platform.

Particle size is a key parameter in selection of wear parts of a centrifugal pump. The selection of wear material is primarily based on the following strategy.

1. The wear material has to be hard to resist cutting action of impinging solids.
2. The wear material has to be elastic to be able to absorb the shocks and rebound of particles.

The dominant wear material in the pumps are hard metal or some sort of soft elastomer with hard metal used for coarser particles (greater than 5 mm).

There is a good table (attached) from Metso slurry pump handbook that explains the effect of particle size on material selection.