A Phased Approach to Test Programs to Meet Feasibility Study Requirements

摘要

The role and importance of a well designed test work program during the development of an orebodyrnis often underestimated. A test work program should be tailored to deliver very specifi c answersrnto relevant questions. With a clear purpose, the results from the test work program will enhancernthe outcome of the feasibility study and provide the information required to meet the requirementsrnof all stakeholders. With regard to test work programs there are three main areas that should bernconsidered: orebody characterisation and defi nition, process fl ow sheet development and engineeringrndesign information.rnOrebody defi nition relies on reliable analytical methods to characterise and assess the economicrnminerals present in the ground. In mineral sands, the physical processing characteristics of thernminerals play a signifi cant role in the defi nition of an orebody. The analytical method thereforernhas to be customised using a combination of laboratory techniques. These techniques can includernheavy liquid separation, gravity separation and magnetic separation and are usually combined withrnchemical and mineralogical analyses to create a picture of the orebody. During the defi nition phasernof test work programs, an appropriate analytical technique has to be developed to evaluate drillingrnsamples, but also to support the information collected during fl ow sheet development.rnProcess fl ow sheet development is usually done once there is a reasonable understanding of the sizernand variability of the orebody. Selecting the best sample for test work is critical, as any fl ow sheetrndesign is tied to the specifi c characteristics of the sample used for development. There are otherrnfactors that can improve the outcomes of fl ow sheet development test work, including the skills andrnknowledge of the operator and allowing suffi cient time to process and analyse the results. Very oftenrnthis work is conducted under pressure with limited time and resources, only to result in a suboptimalrnfl ow sheet. During this phase of fl ow sheet test work, iterative testing will provide the informationrnrequired to develop an optimal metallurgical fl ow sheet. The data collected will provide indicativernrecoveries and yields that are required for feasibility studies.rnEquipment specifi cation is often included as part of process fl ow sheet development. This includesrncomparative test work between different equipment suppliers, assessment of operating conditionsrnsuch as the loading to determine the number of processing units required, as well as other designrninformation required such as particle size distributions, density and operating temperatures.rnWhile restricting the time and costs expended on test work programs may seem to meet a short termrnneed to meet investor requirements, neglecting to develop a proper framework of the requirementsrnthat has to be met in the long-term can lead to signifi cant long-term cost overruns. This is mainly duernto a need to repeat test work, or do confi rmation test work, as insuffi cient information was collectedrnduring the initial program.