Treaceability of raw materials in process streams
Traceability, defined as the ability to preserve and access the identity and attributes of a physical supply chain’s objects, gives the advantage to have a better control over the material through a process and allows for necessary adjustments. It can show “the current” values of different parameters and how much adjustment is needed to achieve the goals. The ability to trace a product backward throughout the process to locate the cause of a defect is therefore a vital ability for any industry.
Traceability is much easier to use in batch processes than in continues processes. In food and pharmacy industries it is very common to use different traceability tools but within the mining industry, which usually operates continuous processes, traceability is an untouched area.
In November 2006 LKAB started the new pelletization plant at Malmberget (MK3). The raw material is a mix from Kiruna and Malmberget ores, i.e. different ores having different Fe-content and levels of contaminants are treated in one process. Therefore traceability of the material throughout the process is one of the crucial factors for future product development and quality insurance.
Objectives
The main task is to find a way to make the traceability easy and practical. One way to reach good traceability would be to find a process mineralogical signature or identification. For having a good traceability we need information from the system. It is important to analyse and look into the variables that have a crucial importance to the process.
Approach
To have a good view over the different samples, Particle Texture Analysis (PTA) was done at NTNU, Trondheim, Norway. The PTA data system is based on the Oxford Inca Feature software and an existing scanning electron microscope (Moen, 2006). Using Back Scattered Electrons (BSE) the images are analysed by means of grey level and every grain of interest is analysed with X-rays.
Results and conclusions
The combination of PTA and MVDA seems to be a promising development. Further refinements would be to use MVDA models to discriminate between “good” and “bad” feed materials using SIMCA classification techniques. By comparing different sections and different minerals it can be shown how the cobbing stage affect the circuit. By comparing the feldspar and apatite it is obvious that the apatite continue to exist during the whole circuit, while most of the feldspar is separated after the first separation stage. It seems that the free particles disappear while mixed particles continue to exist in the circuit.
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