ORE SORTING AND GRAVITY
advantages, eco-friendly processing, low energy consumption as well as potential cost reduction due to obviating process water circuits, product and tailings dewatering and drying processes.
AKA-FLOW functions on a combination of an air fluidised bed with a specially developed sifter.“ Studies with different raw materials have shown outstanding performance both in terms of throughput, as well as classifying,” the company reports. The optimum grain size ranges from 30 µ m to 2 mm. Throughput ranges, depending on the material, between 3 and 6 t / h and 9 and 18 t / h with units of 400 mm and 1,200 mm width.
Product purity and output, can be influenced by five adjustable parameters: n The feed mass flow, which is controlled via a vibro channel. With the assistance of the vibro channel this allows an equal distribution of the feed material over the screening surface n The split preparation, which has influence on the amount of the intermediates n The number of strokes, which are controlled via the rpm of the unbalanced drives. The higher the frequency the faster the material transport via the screening surface n The amplitude, which can be changed through the adjustment of the weights n Airflow, which is produced by a fan, passes
from below through the screening surface. This generates the fluidised bed.
Sorting innovation
Comex AS of Norway has developed a new sorting system, which its says“ is tailor made for separation of metal ores of different types. It makes it possible to separate different mineral particles regarding their colour, shape, texture, size and their composition. The sorting system has been successfully tested and applied in the industrial scale, for sorting of iron ore, providing significant economic improvements.”
Two sensing methods are combined in the same unit: image analysis is carried out by the camera and the X-ray attenuation analysis is realised by the new type XRT detection system in the central part of the machine. The sorting system can be used with both optical and XRT analysis or separately depending on the application. The particle recognition used to separate different materials is based on a complex shape and colour analysis where the particles can also be identified by over 20 parameters used for shape description. Additional combinations of these parameters can also be used for distinguishing particles of interest. Finally, the XRT picture is integrated into the optical analysis, which provides a lot more information about the particle surface properties and its internal structure. This
analysis provides much more complex information about the analysed particles rather than colour recognition alone.
The picture shows the optical and X-ray image of zinc-lead ore particles indicating yellow-red areas with high metal concentration and blue areas with low or no metal content. The images show the results from the DMS( dense media separation). After sending these fractions through the Comex CXR-1000 sorting unit, it was possible to find that the high-density fraction( the left image) still contained many gangue particles( blue) which contain little or no metal. After using the CXR sorter, it was possible to make the same separation much more accurately and in addition with no water and complicated DMS system elements. Finally, the cost of separation was approximately 10 times lower when compared to the traditional DMS operation.
Comex notes:“ This brings enormous potential in metal ore processing where preconcentration of the processed material can provide many benefits in the form of reduced cost and solving of hard environmental issues. This may result in new possibilities for optimising existing circuits and making new installations more economical.”
Successful outcomes from the EU-funded I 2 Mine( Innovative Technologies and Concepts for the Intelligent Deep Mine of the Future)