SE027D -Sensors for Mineral Processing

A mineral processing company is interested in exploring methods to inspect and sort pyrometallurgical waste by-product (slag/rock) fragments to determine which fragments are rich in mineral content and to separate them from the non-recoverable or discard fragments.

It is estimated that the bulk of the recoverable minerals are contained in only 5% of the total waste by-product fragments. This 5% has sufficient mineral content for economical recovery if it can be identified and separated from the discard material.

It is not sufficient to simply reprocess all pyrometallurgical waste by-products.

The principal technical objectives include the following tasks:
(1) Identify potential discriminator properties that distinguish between mineral rich fragments and mineral poor fragments.
(2) To establish assessment techniques that can distinguish between mineral-rich mine waste and discard mine waste.

General specifications are:

To process the large volume of waste material in a timely and economic fashion the fragments must be evaluated on a conveyor belt and pass by a sensor bay. As such all technologies should meet the following specifications, unless otherwise noted:

• The preferred sensors are non-contact (or minimal contact) ones that can measure discriminator properties without having to stop the belt.
• The sensors must be able to analyze rock fragments of various sizes (diameters ranging from 3 cm to 30 cm)
• The sensors must be able to operate in a conveyor operational environment, or be adapted to work in such a setting.
• The sensors must be able to measure and report a discriminatory value in a minimum amount of time.

Chemical Element Sensor:

The main base metals recovered are Copper (Cu), Nickel (Ni), and Cobolt (Co). A non-contact sensor to detect the presence of significant amounts of one or more of these elements is desired. In addition, these elements are most often associated with the element Sulphur (S), so a sensor to detect the presence of S (alone or with Cu, Ni, and Co) would suffice.
In general, it is best if the sensor can give a quantitative measure of the amount of the elements present in the rock sample. The reported measured value can be the combined total of all four elements or the total content of one or more of the elements. The measured value can be actual or relative.

Mineral Sensor

The recoverable metallic elements are contained in or associated with specific minerals. A sensor that can detect the presence of these minerals, and preferably report a actual or relative quantitative value, is required. The elements of interest are contained in or associated with sulphide minerals, i.e. those that contain sulphur. A sensor that can detect metallic (Fe, Ni, Cu, Mg, Co) sulphide minerals is required. However, the ability to identify one or more of the following minerals may be appropriate: pyrrhotite, troilite, and pentlendite.

Density Measurements

One difference between mineral bearing rock fragments and waste rock fragments is density. A device that can discriminate between rock samples using the properties of density is required. The instrument can measure and report true density, specific gravity, or any feature related to density. If a device that directly measures density is found, it must be able to report density to the 10th of a g/ml.

Volume Measurements

A tool to calculate the volume of rock samples is required. The tool should be able to determine the volume of rock samples to the nearest ml (or some similar sized unit).

Mass Measurements

An instrument, that meets the "General Specifications" above, is required to measure the mass of rock samples to the nearest 10th of a gram or better.

Electrical Properties

The resistivity of mineral bearing samples is different then the resistivity of discard samples. As such, an instrument is required to measure the resistivity (or its inverse, conductivity) of rock samples. It is preferred that such a tool be non-contact, but in this case it is not required. An alternative, is an instrument that can measure the resistance across a sample.
Since we only want to discriminate rock samples that contain base metal minerals from those that do not, the requirement for this device is more general. Any instrument that uses electrical properties (such as resistivity, dielectric constant, chargability, etc.) to produce some quantitative value that can be used to compare any two samples is sufficient.

Electromagnetic (EM) Properties

Many geophysical devices exist that use EM properties of base metal minerals as a means of exploration and ore body evaluation. A similar, metal detector-like, device is needed to exploit differences in the EM properties of rock fragments that contain base metal minerals (sulphides) versus those that do not. More specifically a tool is needed that can emit a primary EM field and measure the secondary EM field that is produced in the rock sample in response to the primary field.

Infrared Imaging Device (Thermal Imaging Camera)

A thermal imaging camera device that can detect temperatures between +40 C to -40 C and has a temperature resolution of 0.05 C or less is required. In order to interpret IR images, an image processing software library is also needed.

To obtain more information on the request, please contact Nodal Consultants