Conv-LSTM for Real Time Monitoring of the Mineral Grades in the
Flotation Froth
Ahmed Bendaouia
1,2 a
, El Hassan Abdelwahed
1 b
, Sara Qassimi
4 c
, Abdelmalek Boussetta
3
,
Intissar Benzakour
3
, Oumkeltoum Amar
2
, Franc¸ois Bourzeix
2
, Achraf Soulala
1
and Oussama Hasidi
1,2
1
Computer Systems Engineering Laboratory (LISI), Computer Science Department, Faculty of Sciences Semlalia, Cadi
Ayyad University, Marrakech, Morocco
2
SEIA Departement, Moroccan Foundation for Advanced Science Innovation and Research (MAScIR), Rabat, Morocco
3
R&D and Engineering Center, Reminex, Managem Group, Marrakech, Morocco
4
Computer and Systems Engineering Laboratory (L2IS), Computer Science Department,
Faculty of Science and Technology, Cadi Ayyad University, Marrakech, Morocco
Keywords:
Deep Learning, Industry 4.0, Flotation Froth, Mining Industry, Monitoring.
Abstract:
Accurate monitoring of the mineral grades in the flotation froth is crucial for efficient minerals separation in
the mining industry. In this study, we propose the use of ConvLSTM, a type of neural network that combines
Convolutional Neural Networks (CNNs) and Long Short-Term Memory (LSTM) networks, to create a model
that can extract spatial and temporal patterns from flotation froth video data. Our model enables the analysis of
both spatial and temporal patterns, making it useful for understanding the dynamic behavior of the froth surface
in the flotation processes. Using ConvLSTM, we developed a more accurate and reliable model for monitoring
and controlling the flotation froth quality. Our results demonstrate the effectiveness of our approach, with mean
absolute error (MAE) of 2.59 in a lead, copper and zinc differential flotation site. Our findings suggest that
artificial intelligence can be an effective tool for improving the flotation monitoring and control, with potential
applications in other areas of the mining industry.
1 INTRODUCTION
In recent years, research has demonstrated a signifi-
cant decline in mineral resources. This decline can be
attributed to both the depletion of existing mineral re-
serves and the unpredictable reductions in raw materi-
als. In response to these challenges, the mining indus-
try has been compelled to innovate in various aspects
of its operations, including mining, exploration, pro-
cessing, logistics, and marketing. This industry-wide
push towards innovation has been further supported
by the emergence of the fourth industrial revolution,
also known as Industry 4.0. This revolution is char-
acterized by the integration of digital technologies
and physical systems, resulting in the development
of smart factories that are highly productive and ef-
ficient. Industry 4.0 is reliant on a range of disruptive
a
https://orcid.org/0000-0003-0017-9285
b
https://orcid.org/0000-0002-2786-6707
c
https://orcid.org/0000-0002-9441-986X
technologies, including the Internet of Things (IoT),
cloud computing, big data, and Cyber-Physical Sys-
tems (CPS) (Qassimi and Abdelwahed, 2022). Within
this context of digital transformation, our study aims
to investigate how disruptive technologies and inno-
vations can be utilized to optimize mineral processing
productivity and efficiency in the mining industry.
Given the challenges facing the mining indus-
try regarding the declining mineral resources and the
need for innovation, one technique that has gained
significant attention is the flotation separation. The
flotation has emerged as a promising technique in the
last century. It is a mineral processing method that
leverages the differences in surface properties of min-
erals to separate them (see figure 1). This approach
is widely employed in the mining industry to extract
valuable minerals from ores. Recent developments in
technology and research have led to the creation of
new flotation separation methods, including the use of
innovative reagents and equipment. Against the back-
drop of the digital transformation of the mining indus-
Bendaouia, A., Abdelwahed, E., Qassimi, S., Boussetta, A., Benzakour, I., Amar, O., Bourzeix, F., Soulala, A. and Hasidi, O.
Conv-LSTM for Real Time Monitoring of the Mineral Grades in the Flotation Froth.
DOI: 10.5220/0012090100003541
In Proceedings of the 12th International Conference on Data Science, Technology and Applications (DATA 2023), pages 89-96
ISBN: 978-989-758-664-4; ISSN: 2184-285X
Copyright
c
2023 by SCITEPRESS Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)
89
Figure 1: Froth flotation separation technique.
try and the need for enhanced efficiency and produc-
tivity, this research aims to propose a new flotation
monitoring technique based on artificial intelligence
that can be utilized to optimize the flotation monitor-
ing.
This paper focuses on the monitoring of the flota-
tion froth and proposes a cost-effective and low-
maintenance solution that enables real-time measure-
ment of mineral grades. To achieve this goal, we
employ artificial intelligence and deep learning tech-
niques in the mineral processing flotation-based. This
paper is organized into five sections. The first section
provides an introduction and outlines the general con-
text of the research, while the second section presents
the state of the art in flotation froth monitoring and
the use of deep learning techniques. The third sec-
tion details the methodology employed, including the
data types and preprocessing steps, model architec-
ture, and experimental process. The fourth section
reports the application and results of the proposed so-
lution, including mineral grade identification, perfor-
mance evaluation, and discussion. Finally, the fifth
section offers a conclusion and perspective on the re-
search findings.
2 STATE OF THE ART
2.1 Flotation Froth Monitoring
To achieve the optimization and control of the flota-
tion process, accurate monitoring of the flotation con-
centrate grades is crucial. While several existing
monitoring techniques are available, they can be ex-
pensive to implement and may have high mainte-
nance requirements in addition to their latency. Cur-
rently, the most used monitoring techniques are XRF-
fluorescence-based or laboratory analysis basically
the Atomic Absorption (AA). The laboratory analysis
method is considered the most accurate but has limita-
tions due to manual sampling and preparation, leading
to latency issues. The online mineral control method
using X-ray fluorescence (XRF) detection, specifi-
cally the XRF-based Courier 6G, is used at the Com-
pagnie Mini
`
ere de Guemassa (CMG) flotation factory
where this study was conducted. This method can
measure up to six individual process streams, mak-
ing it suitable for monitoring complex polymineral-
lic flotation circuits that contain lead, copper, iron
and zinc. However, XRF analysers require contin-
uous and high-cost maintenance and suffer from in-
sufficient detection of lightweight materials (Uusitalo
et al., 2020).
2.2 Deep Learning for Flotation
Monitoring
In recent years, both literature and practical experi-
ence acknowledge that the visual characteristics of
the froth surface are significant and strongly corre-
lated with the quality of the flotation froth (Liu et al.,
2020) (Farrokhpay, 2011) (Kaartinen et al., 2006)
(Aldrich et al., 2022). This alternative solution for the
flotation monitoring based on Machine Vision is not
only cost-effective but also requires minimal main-
tenance. Furthermore, the visual inspection of the
flotation froth offers the added benefit of enabling
real-time measurement of mineral grades, providing
a significant improvement over current monitoring
techniques such ad XRF-fluorescence and laboratory
analysis. The biggest portion of these applications
are froth classification based on Convolutional Neu-
ral Networks (CNN). Basically because of the capac-
ity of CNN to learn rich hierarchical sets of features
from images. Furthermore, CNN enables the com-
putational power of the deep learning to extract the
features from froth images for classification (Zhang
and Gao, 2021) (Zarie et al., 2020) (Cao et al., 2022)
(Wen et al., 2021). CNNs have proved their capa-
bility of determining the mineral grades more ac-
curately than the classical Machine Learning along
with the supervised features extraction of the flota-
tion froth (Bendaouia et al., 2022). In addition to the
CNNs, Long Short-term-memory based (LSTM) net-
works was used for mineral grades monitoring using
flotation froth video sequences (Zhang et al., 2021).
LSTM architecture is also used for damage detection
in pipelines (Huang et al., 2022), anomaly detection
for technical systems (Lindemann et al., 2021) and
predicting the electric power consumption (Cascone
DATA 2023 - 12th International Conference on Data Science, Technology and Applications
90
et al., 2023). Researchers and engineers are benefit-
ing from the LSTM capability of extracting temporal
patterns in time series data.
The froth flotation video sequence can be con-
sidered as temporal information that can improve the
monitoring accuracy. Therefore, in our study, we pro-
pose the use of ConvLSTM to create a model that
can extract spatial and temporal patterns from flota-
tion froth. ConvLSTM is a type of neural network
that combines the properties of Convolutional Neu-
ral Networks (CNNs) and Long Short-Term Memory
(LSTM) networks. This allows the model to analyze
both spatial and temporal patterns in data, making it
useful for understanding the dynamic behavior of the
froth surface in flotation processes. By using ConvL-
STM, we created a more accurate and reliable model
for monitoring and controlling the flotation froth qual-
ity.
3 METHODOLOGY
The flotation process is a physio-chemical process
that is influenced by numerous parameters. The min-
erallurgist operators acquire the expertise of visually
monitoring the flotation froth based on the froth char-
acteristics. An important factor is the color and tex-
ture of the froth surface, which contains valuable in-
formation about the mineral composition (Farrokh-
pay, 2011). By identifying the mineral types based on
the color and texture of the froth surface, the flotation
performance can be assessed, and operation instruc-
tions can be adjusted accordingly.
In this study, we propose a digital approach that seeks
to replicate the expertise of human operators in visu-
ally monitoring the flotation froth. Specifically, we
propose the use of Conv-LSTM, which combines the
strengths of Convolutional Neural Networks (CNNs)
in image classification with Recurrent Neural Net-
works (RNNs) for processing sequential data, such
as video frames figure 2. By using Conv-LSTM, we
can extract sequential characteristics from the video
frames of the flotation froth, enabling a more accu-
rate assessment of the mineral composition and thus
better optimization of the flotation process.
3.1 Experimental Process
The experimental process employed in our study
to predict the percentages of minerals in flotation
cells using a Convolutional Long Short-Term Mem-
ory (ConvLSTM) network consisted of the following
steps:
Data Collection: A large dataset of labeled video
frames of the flotation froth of the Zn circuit was
collected, where each video frame was labeled
with the corresponding percentages of the four
minerals (Zn, Cu, Fe, and Pb) in the flotation
froth.
Data Preprocessing: The collected video frames
were preprocessed by resizing them to a consis-
tent size and format and splitting them into se-
quences of frames that could be used as input to
the ConvLSTM network.
Model Architecture: The model architecture was
defined using the Sequential class. The hyper-
parameters were selected after many training and
evaluation operations.
Model Training: The model was trained using the
labeled video sequences as input and the corre-
sponding percentages of the minerals as output.
The model was trained for several epochs using
the Adam optimizer and the mean squared error
(MSE) as the loss function.
Model Evaluation: The trained model was eval-
uated using a separate test dataset of video se-
quences and corresponding mineral percentages.
The model’s performance was measured using
metrics such as accuracy and mean squared error.
Model Deployment: The trained model was de-
ployed for use in the flotation froth cells, where it
was used to predict the percentages of the miner-
als in real-time. The predictions were utilized for
monitoring the flotation process and improve the
efficiency of the separation of the minerals.
3.2 Data Collection
We collected a real world dataset from the differential
flotation site of CMG Managem group in Morocco
figure 3. This dataset includes visual aspect parame-
ters and the elemental composition of Pb, Cu, Zn and
Fe. During the data collection phase, we collected a
sample from the flotation froth and analyzed it in the
laboratory using atomic absorption. Additionally, we
recorded a video of the flotation froth using an RGB
camera under stable luminosity to capture the visual
aspect parameters as described in the figure 4.
3.3 Data Augmentation
To further explain the approach used in the study, the
following paragraph describes the dataset and model
used for training and testing. The study utilized 340
videos from the flotation site of CMG Managem-
Group in Morocco, which were processed into seven-
frame sequences with each frame having a shape of
Conv-LSTM for Real Time Monitoring of the Mineral Grades in the Flotation Froth
91
Figure 2: Framework of the LSTM-based mineral grade monitoring system using the froth flotation video data.
Figure 3: The data acquisition system of the flotation froth
videos.
224x224x3. The sequences were then used as input
for a recurrent neural network (RNN) designed to pre-
dict the percentages of copper (Cu), iron (Fe), lead
(Pb), and zinc (Zn) in the videos. The dataset was split
into 313 training videos and 27 testing videos, with
each target value containing the concentrations of Cu,
Figure 4: The data sources and types.
Fe, Pb, and Zn. The seven-frame sequences and target
mineral grades were combined to enable the model to
accurately predict mineral concentrations by captur-
ing the patterns and dependencies in the data. Ad-
ditionally, the data was augmented by adding noise
between 0 and 0.25 to artificially increase the dataset
size and improve the model’s performance. The con-
trolled addition of noise was an effective way to in-
troduce variability and diversity into the labels while
preserving their overall structure and meaning.
3.4 ConvLSTM-Based Network
We are using ConvLSTM to build a model that can
extract simultaneously both spatial and temporal pat-
terns from the flotation froth. ConvLSTM is a type of
recurrent neural network that combines the strengths
of CNNs and LSTMs, allowing it to process both spa-
tial and sequential data effectively. In a ConvLSTM,
convolutional operations are applied to the input, for-
get, and output gates of an LSTM cell, enabling the
network to learn spatial and temporal patterns simul-
DATA 2023 - 12th International Conference on Data Science, Technology and Applications
92
taneously. This makes ConvLSTM a powerful tool for
tasks such as video prediction and time-series fore-
casting. The equations for a ConvLSTM cell are
shown below:
i
t
= σ(W
xi
x
t
+W
hi
h
t1
+W
ci
c
t1
+ b
i
)
f
t
= σ(W
x f
x
t
+W
h f
h
t1
+W
c f
c
t1
+ b
f
)
c
t
= f
t
c
t1
+ i
t
tanh(W
xc
x
t
+W
hc
h
t1
+ b
c
)
o
t
= σ(W
xo
x
t
+W
ho
h
t1
+W
co
c
t
+ b
o
)
h
t
= o
t
tanh(c
t
)
x
t
is the input at time step t
h
t1
is the hidden state at time step t 1
c
t1
is the cell state at time step t 1
i
t
, f
t
, o
t
are the input, forget, and output gates,
respectively, at time step t
σ is the sigmoid activation function
denotes convolution operation
denotes element-wise multiplication
W and b are the weight matrices and bias vectors,
respectively, for the input, hidden state, and cell
state
4 Conv-LSTM FOR MINERAL
GRADES DETERMINATION
4.1 Model Architecture
The ConvLSTM network architecture was used in our
study to predict the percentages of four different min-
erals in flotation cells from video data figure 5. The
architecture was effective in processing both the spa-
tial and temporal information present in the video
frames and sequences, which was crucial for our task.
In addition to the ConvLSTM layer, the model also in-
cluded a BatchNormalization layer, a MaxPooling3D
layer, a Dropout layer, a Flatten layer, and a Dense
layer. The Adam optimizer with a low learning rate
of 0.0001 was chosen for its effectiveness in adapt-
ing the learning rate for each parameter and avoiding
overshooting the optimal solution.
4.2 Performance Evaluation
To evaluate the performance of our model in predict-
ing the percentages of the mineral grades from the
froth video, we utilized a separate test dataset that
was not used during the training process. Evaluation
was conducted using several metrics, including accu-
racy, mean squared error (MSE), mean absolute error
(MAE), and mean absolute percentage error (MAPE).
Evaluation is particularly crucial for this study aim-
ing to predict mineral percentages from froth videos
for several reasons. Evaluation allows us to deter-
mine how close the model’s predictions are to the true
values and how much error is present in the predic-
tions. This information can be leveraged to choose the
best model for deployment or identify the key factors
that influence the model’s performance. As the model
is deployed and new data is collected, it is essential
to assess its performance to ensure that it continues
to make accurate predictions. The figure 6 shows a
comparison between the measured and the predicted
mineral grades using our proposed model. The ta-
ble 1 evaluate the model according to the MSE, MAE,
MAPE evaluation metrics. The Standard deviation
(STD) was also calculated for the different elements
in the data test.
Table 1: The evaluation metrics of the ConvLSTM model
on datatest.
Elements Evaluation metrics
MSE MAE MAPE STD
Zn 11.43 2.59 6.22 16.10
Cu 0.66 0.68 77.70 0.31
Fe 5.81 1.98 15.037 10.54
Pb 0.168 0.313 65.51 0.78
4.3 Discussion of the Results
The table 1 displays the MSE, MAE, and MAPE val-
ues for each elemental composition. Each metric
value corresponds to a specific target mineral. For the
Zn mineral, the MAE value is 2.59, and the MAPE
value is 6.22 while the standard deviation is 16.10,
which is an accurate result according to the variation
of the Zn mineral grade in the Zn flotation circuit. The
low values for these metrics indicate that the model
is making more precise predictions according to high
standard deviation of the Zn mineral grades. Addi-
tionally, the table emphasizes that the model’s perfor-
mance varies depending on the mineral, which is due
to the variety of the concentrate grades distributions.
Compared to other minerals, the Copper has lower
MSE, MAE, and MAPE values, indicating that the
model is making more accurate predictions for this
particular mineral.
The model’s performance varies among the differ-
ent minerals. Overall, the predictions are more accu-
rate for the low grade elements copper (Cu) and lead
(Pb).
Conv-LSTM for Real Time Monitoring of the Mineral Grades in the Flotation Froth
93
Figure 5: The used architecture for the Zn, Fe, Cu and Pb mineral grades prediction.
Figure 6: The measured values of copper, zinc, lead, and iron with the predicted values provided by the ConvLSTM-based
network on deployment data.
5 CONCLUSIONS
Our study demonstrated the added value an indus-
trial application of artificial intelligence in mining in-
dustry. We used a Convolutional Long Short-Term
Memory (ConvLSTM) network to accurately predict
the percentages of minerals in real time in flotation
froth. By utilizing video data as input, the model was
DATA 2023 - 12th International Conference on Data Science, Technology and Applications
94
able to effectively process both spatial and temporal
information, resulting in precise predictions of min-
eral percentages. Our proposed approach has a direct
added value on the monitoring of flotation processes.
The model demonstrated a good level of accuracy and
precision, indicating its ability to be generalized on
the whole differential flotation. The use of the Con-
vLSTM network in flotation froth monitoring, show-
cases its potential for similar industrial applications
that require processing of spatial and temporal infor-
mation.
The real time monitoring the flotation froth is a cru-
cial aspect of optimizing and controlling the flotation
process. Our proposed approach offers significant ad-
vantages over existing monitoring techniques, as it is
not only less expensive and low-maintenance but also
provides real-time information on mineral grades.
This makes it a valuable addition to the flotation mon-
itoring process. Once implemented on the zinc cir-
cuit, our proposed soft sensor will be tested for its
ability to accurately monitor the mineral grades of the
CMG differential flotation circuit’s three base miner-
als: lead, copper, and zinc. By combining froth fea-
tures, physio-chemical sensors, and intelligent control
techniques, this innovative approach has the potential
to become a reliable and effective flotation monitor-
ing system. Our proposed approach of using Con-
vLSTM neural networks for real-time monitoring of
mineral grades in flotation froth has significant po-
tential for future industrial applications beyond lead,
copper, and zinc differential flotation sites. Specif-
ically, we will be testing the generalization of our
approach to other mineral compositions using froth
video data, an aspect that will be addressed in future
work. We acknowledge the limited experimental data
used in this study and are committed to conducting
further research to validate the effectiveness of our
proposed solution in a wider range of industrial set-
tings.
ACKNOWLEDGEMENTS
The Smart Connected Mine project, which this re-
search is a part of, was supported by the Moroccan
Ministry of Higher Education, Scientific Research
and Innovation, the Digital Development Agency
(DDA), and the National Center for Scientific and
Technical Research of Morocco (CNRST) through
the Al-Khawarizmi program. The project was a
collaboration between MASCIR (Moroccan Founda-
tion for Advanced Science, Innovation and Research),
REMINEX R&D (an engineering and project man-
agement subsidiary of the MANAGEM Group), UCA
(Cadi Ayyad University), ENSMR (National School
of Mines of Rabat), and ENSIAS (National School
of Computer Science and Systems Analysis at Mo-
hammed V University). We would like to express our
gratitude to the MANAGEM Group and its subsidiary
CMG for providing us with the opportunity to conduct
research, collect and validate data on-site, and for be-
ing an industrial partner in this project.
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