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Author: Admin | 2025-04-28
Similar manner. However, the metal concentration measured in the final underflow samples from each train often differed dramatically, with Train 1 always reporting a lower concentration than Train 2.Plant engineers tended to dismiss this variation as poor sample collection and filtering, as there had been perceived issues with this in the past. An investigation had been conducted, which concluded that the sampling methods were theoretically sound and the same for both circuits.Using the modern approach, it became possible to compare the assay results from the two CCD trains over a large period. From this, it appears that the underflow metal concentrations measured in CCD Train 2 are usually higher than those for CCD Train 1. A correlation analysis between the two variables proves this (Figure 1). Figure 1 – Correlation between CCD Train 1 & 2 Underflow Metal Concentration Now that we have proven that the CCD Train 2 values are consistently higher than those for Train 1, the question becomes whether this is an accurate depiction of what happens in the plant. To determine this, we need to compare the measured values from the laboratory against the calculated values from the dynamic mass balance. Figure 2 – Calculated and Measured Values for CCD Train 1 & 2 Underflow Metal Concentration Figure 2 shows the measured and calculated values for the two variables over time. At first glance, these appear to align closely, except for a few particularly high measured values.The close correlation between the measured and calculated values suggests that assay results from the two sample points are accurate. This means the dynamic mass balance, based on measurements from across the whole process plant, indicated that the metal concentration in the CCD Train 2 underflow is consistently higher than that in CCD Train 1.The next question then becomes: why is the concentration leaving CCD Train 2 higher than that leaving Train 1? This appears to be driven by the relative amounts of wash water that were added to the two circuits. Figure 3 shows the correlation between the wash ratio [wash volume] / [underflow volume] for CCD Trains 1 and 2. This shows that the CCD Train 2 wash ratio was often much lower than that for Train 1, and that there also appeared to be interruptions in the water going to the CCD Train 2 wash. Figure 3 – Correlation between CCD Train 1 & 2 Wash Ratios Finally, Figure 4 shows the relationship between wash ratio and underflow metal concentration for CCD Train 2, indicating that low wash water flow is related to higher underflow metal concentrations. Figure 4 – Correlation between CCD Train 2 Underflow Metal Concentration and Wash Ratio Case Study 2: Comparing measured and calculated data to identify outliersThe second case study comes from the same hydrometallurgical plant as Case Study 1, except this time the goal is to use the relationship between measured and calculated data to identify outliers.Figure 5 shows the measured and calculated metal concentration values in seven related plant streams
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