Modernizing Your Assay Lab for Lateritic Nickel Ore Mining - Observing the Present Our expertise

As with lateritic ore, the valuable content is in the soil exposed to the elements. Sun and rain will affect the water and moisture content, which will affect the chemical concentration per weight due to dilution factors. As such, it is important for any buyer to know the moisture content and hence determine the actual weight and value of the materials.

On average, the water content in the sample will range from 20 to 50 percent. A simple method of determination is by proper sampling and a quantity of the samples are then weighed before and after being placed in a heating oven, usually at approximately 105 degrees Celsius, for an hour to ensure all trapped moisture are evaporated. The weight difference can then be used to calculate the moisture content of the sample.

Cargoes that contain a certain proportion of small particles and a certain amount of moisture may liquefy when the moisture content exceeds the Transportable Moisture Limit (TML). In the resulting viscous fluid state, cargo may flow to one side of the ship with a roll one way but not completely return with a roll the other way, causing the ship progressively to reach a dangerous heel and capsize suddenly. The TML is determined by sampling the cargo correctly and determining the FMP.

The flow table test is primarily used to determine the FMP of relatively homogenous mineral cargos. The test requires a cargo sample in the form of a truncated cone to be placed on a flow table, raised, and dropped repeatedly, around 50 times, from a measured height.

The elements of values need to be determined as it will define the price of each batch. For typical analysis, Fe, Ni, and Co are the main elements to be determined. However, for mining exploration purposes, all elements need to be known and screening is necessary as some elements will increase or decrease the value of the ore.

Chemical analysis can be performed with various techniques from manual titration to AAS/ICP-OES. Many mining labs prefer the EDXRF method as this technique uses minimal sample preparation, is easy to operate, and provides the fastest sample-to-results. There is no sample dissolution or harsh chemicals involved in the analysis.

Collected samples are dried in an oven, pulverized into a fine powder, and then pressed into a solid pellet using a hydraulic press, which can then be analyzed directly in an EDXRF instrument. Occasionally a sample will be taken for titration analysis for cross-checking.