Optimisation of tungsten ore processing through a deep mineralogical characterisation and the study of the crushing process

Abstract

The unstoppable increasing global demand for metals calls for an urgent development of more efficient extraction and processing methods in the mining industry. Comminution is responsible for nearly half of the energy consumption of the entire mining process, and in the majority of the cases it is far from being optimised. Inside comminution, grinding is widely known for being more inefficient than crushing, however, it is needed to reach liberation at an ultrafine particle size. Sometimes the material is excessively reduced in size, while liberation could be achieved at a coarser scale. Therefore, in this work a deep characterisation of a specific tungsten ore is performed in order to find guidance in optimising the processing. Either by discarding and avoiding the unnecessary crushing of uneconomic material or any other useful recommendation. The aim is that the methodology utilised for the characterisation of the material, can be applicable to other ores, with the purpose of initiating the optimisation of the mineral processing. This thesis is divided in two main parts: the mechanical characterisation of the breakage and the mineralogical characterisation. For the first part, the breakage behaviour of the sample material will be studied and described in terms of particle size distribution after interparticle breakage. The latter will be assessed in terms of the different minerals and tungsten concentrations and mineral associations, through the use of image analyses (scanning electron microscope), X-Ray diffraction of crystalline dust and chemical analyses. The liberation and fracture characteristics that occur due to compressive crushing will be analysed. Furthermore, recommendations in the processing of the ore will be detailed, along with potential problems that should be avoided during its exploitation or the own processing. Results show that it is possible to obtain ore liberation during coarse comminution. Moreover, preconcentration of the tungsten ore at coarse scale and early rejection of gangue has been determined to be achievable due to the tendency of the ore to concentrate in specific size fractions.