The loaded organic tank receives the solvent (also referred to as the organic phase) from the extraction stage (generally demarcated as E1) that is loaded to a high level, with the target metal, transferred from the contacted Pregnant Leach Solution (PLS). The aqueous phase that is mixed with the organic phase in the E1 extraction stage unit can be trapped ("entrained") in the organic phase, during phase to a varying degree. This phenomenon is called "aqueous entrainment in the loaded organic phase". However, they will be referred to as "loaded organic aqueous entrainment" as it is detected in the exiting loaded organic phase being transferred from E1 to the Loaded Organic Tank.

Plant operator who are in charge of ensuring continuous and normal operation of the SX plant.

Two types of aqueous entrainment are distinguished based on the rate at which they occur.

Fast entrainment means that a large amount of aqueous phase is entrained in the loaded organic stream exiting the E1 settler and entering the loaded organic tank in short span of time. The limits which define "large amount" and "short span" are specific to the various sites and are communicated to the users therein individually.

Slow entrainment refers to the gradual buildup of aqueous phase in the loaded organic tank due to lower aqueous entrainment volumes in the loaded organic exiting the E1 settler.

Two detectors have been developed:

a. one that monitors the fast aqueous entrainment and

b. one that has been trained to identify slow aqueous entrainment.

The detector monitors the loaded organic tank level and the sensor readings of the loaded organic transfer pump attached to the loaded organic tank. It then tries to deduce from these observation whether entrainment is happening or not.

The fast aqueous entrainment detector emits a zero when it assumes that no fast entrainment is happening and one when it deduces there is entrainment.

*Please note, that there are instances when the detector is instructed to return a blank which will be discussed in the Limitations section.

The slow aqueous entrainment detector emits an entrainment severity score which ranges between zero and one; zero meaning no entrainment detected. One being the indicator of severe -- fast -- entrainment. The score is related to the rate at which the tank level changes. The exact mapping between rates and scores is specific to the client site and it is communicated to the personnel individually.

The length of the period during which it is assumed the aqueous phase is entrained.

The Loaded Organic Tank Stability Dashboard collates the widgets that pertain to the aqueous entrainment.

This widget displays a real time 0/1 alert whether it detects fast aqueous entrainment an image of which is shown in Figure 1. The spikes reaching up to one indicate fast aqueous entrainment, the constant segments at zero signify the absence of it, whilst the gaps are due to either missing data or data quality requirements being violated.

Figure 1. Fast Aqueous Entrainment Alert Widget.

This widgets provides real life information of the severity of aqueous entrainment. As Figure 2. illustrates the continuous scale of the aqueous entrainment severity. Please observe that high instances of high severity tend to coincide with fast aqueous entrainment alerts. It is not necessary a one-to-one correspondence because the data used by the the slow aqueous entrainment detector need to fulfill a more extensive set of criteria.

Figure 2. (Slow) aqueous entrainment severity.

This widget displays the length of time that the signal that caused the detector to emit the current warning persists. Please note that this widget is supposed to be used in conjunction with the severity widget. The baseline length of three minutes almost only means entrainment if the severity is not zero.

Figure 3. Aqueous Entrainment duration.

This widget collates variables that help put the entrainment alerts in context. It shows the loaded organic pump status, the loaded organic pump frequency and the loaded organic tank level.

Figure 4. The loaded organic pump and tank monitor.

This widget is a colour-coded alert which displays the latest value of the loaded organic tank level. The purpose of this widget is two-fold. Firstly, it helps filter out entrainment alerts that can potentially be triggered by the rapid fluctuations of the loaded organic pump current, due to air ingress (pump cavitation). Secondly, it is to alert the operator to the increased possibility of air ingress at low loaded organic tank levels and the subsequent negative impact this has on the extent of stabilization in the receiving Strip Stage mixer to which the loaded organic is being pumped.