Geotechnical Analysis of Mine Tailings: Major Project Report

This report presents a geotechnical analysis of mine tailings, focusing on the laboratory experiments conducted to investigate the geotechnical properties of various tailings, including copper and iron tailings. The study addresses issues such as compression, strength, and permeability, crucial for understanding dam behavior and ensuring safety. The results discuss grain size distribution, specific gravity, plasticity, and compressibility, along with triaxial compression tests. The findings highlight the differences between fine and coarse tailings, as well as copper and iron tailings, in terms of damping ratio, compressibility coefficients, strength, permeability, and cyclic resistance. The study emphasizes the importance of drainage and consolidation for dam safety and the significance of understanding the relationships between tailings characteristics and dam design. The report concludes by agreeing with the authors' proposal that simulation using experimental data is crucial for determining dam tailing's stability under various working conditions.

MAJOR PROJECT: GEOTECHNICAL
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Contents
Introduction.................................................................................................................................................2
Issues addressed by the authors in the article............................................................................................2
Results and Discussions...............................................................................................................................3
Conclusion...................................................................................................................................................4
Lesson learned.........................................................................................................................................5
Agreement with the Authors...................................................................................................................5
REFERENCES................................................................................................................................................6
Introduction
The exploitation as well as use of the mineral resources is known for the production of large
amount of tailing which are usually in the form of slurry and has very high compressibility and
water content. In the last few decades, there has been dramatic increase in the volume of tailing
being generated as the demand of the minerals increase. This particular paper presents the results
of the laboratory experiments which were carried out so as to assist in the investigation of the
geotechnical properties of four various tailings (Silveira et al.2019). They included two copper
tailings which were both course and fine and also two iron tailings (both course and fine).
The rate of failure of the dam which has been on the increase has resulted into the need to
educate or create awareness in regard to the enhanced safety in the design as well as operation of
the tailing dams (Yin et al.2019). These two properties of the dam are known to be highly
dependent on cyclic as well as static characteristics of the tailings applied for the dam
construction in addition to the hydrological and geological condition of the site for disposal
(Schoenberger 2016). The laboratory tests as provided by this particular paper have provided

very useful information that assist in the understanding of the geotechnical behaviour of the mine
tailings including deformation, seepage, seismic responses and strength.
Issues addressed by the authors in the article
The primary aim of the laboratory study was to assist in ascertaining the basic geotechnical
characteristics of the entire tailings which were four in umber. The focus was on:
i. Compression: Focuses on the horizontal forces which are primarily from the silt pressure
and wave pressure which acts against the gravity dam (Slingerland, Schafer and Eaton
2018).
ii. Strength: It is the ability of the dam to resist damage under the influence of forces
iii. Permeability: Highlights the “self –healing” property of the dam as it becomes stable
overtime.
Results and Discussions
The primary geotechnical properties of the dam which include the distribution of the grain size,
specific gravity, permeability, plasticity and finally compressibility were compressively
investigated. This went alongside the performance of the triaxial compression tests. The test was
found to be relevant in the analysis of the cyclic responses as well as the strength of the four
tailings. It is from this test that the two course tailings were classified as the s silty sand (SM)
while the fine tailings were classified as sandy lean clay (CL). The concept of this classification
was guided with the systems of the Unified Soil Classifications (Jeyapalan, Duncan and Seed
1983).
The damping ratio of fine and course tailings was found to be almost the same. This was both for
the case of the fine and course tailings. The ratio of damping was found to increase with the

increase in the shear strain as per the results of the cyclic modulus tests. The tailings of copper
however showed larger ratio of damping than the iron tailings (Santamarina, Torres and Bachus
2019). When compared with the previous tests which had been done by the other scholars, the
damping ratio obtained from the four founding was actually larger than those of zinc and copper.
Figure 1: Graphical representation of the relationship between shear strain and the damping ratio
of the fine and course tailings (Harder and Stewart 1996).
The two fine tailings indicated very large coefficients of the compressibility. The values of the
strength, permeability and cyclic resistance were actually smaller as compared to the other two
coarse tailings in the respective order. According the results, the comparisons between the
copper and the iron tailings clearly showed that tailings of the iron had larger compressibility
coefficients, lower strength, lower permeability and final lower value of the cyclic resistance.

Conclusion
In the case of the course tailings, there was slower accumulation of the pore water pressure in the
early period although this later became faster as the time progressed. This enhanced strength,
permeability and reduced the susceptibility to compressional forces. The study therefore
identified drainage as well as consolidation to be very important factors as far as safety of the
dams are concerned. This is the reason why consolidation stress had very little impact on the
cyclic resistance ratio. In the case of the fine tailings the susceptibility of the liquefaction which
was predicted from the criteria of the empirical was in agreement with the tests of cyclic triaxial.
Lesson learned
It was through this article that I discovered that the dam tailing characteristics though vary in
one aspect or the other are highly dependent on the type of the ore, the mineralogy, chemical
and physical process that are applied in the extraction of this particular economic product. In fact
I discovered that it is through compressive understanding of some of these properties that safety
design of the dam can be achieved (Harder and Stewart 1996).
Agreement with the Authors
I particularly agree with the authors’ proposal that the dam tailing’s stability under various
working conditions can be determined through simulation using numerical values from the
experimental data. This is because the consideration will actually be given to the acceleration of
the process of consolidation which is caused by the increase in coefficient of the compression
(Fontes et al.2016).

REFERENCES
Fontes, W.C., Mendes, J.C., Da Silva, S.N. and Peixoto, R.A.F., 2016. Mortars for laying and
coating produced with iron ore tailings from tailing dams. Construction and Building
Materials, 112, pp.988-995.
Harder Jr, L.F. and Stewart, J.P., 1996. Failure of Tapo Canyon tailings dam. Journal of
Performance of Constructed Facilities, 10(3), pp.109-114.
Jeyapalan, J.K., Duncan, J.M. and Seed, H.B., 1983. Investigation of flow failures of tailings
dams. Journal of geotechnical engineering, 109(2), pp.172-189.
Santamarina, J.C., Torres-Cruz, L.A. and Bachus, R.C., 2019. Why coal ash and tailings dam
disasters occur. Science, 364(6440), pp.526-528.
Schoenberger, E., 2016. Environmentally sustainable mining: The case of tailings storage
facilities. Resources Policy, 49, pp.119-128.
Silveira, F.A., Gama, E.M., Dixon, K.W. and Cross, A.T., 2019. Avoiding tailings dam collapses
requires governance, partnership and responsibility. Biodiversity and Conservation, 28(7),
pp.1933-1934.
Slingerland, N., Schafer, H. and Eaton, T., 2018. Long-term performance of tailings dams in
Alberta. Geotechnical News, pp.50-53.

Yin, S., Shao, Y., Wu, A., Wang, S. and Li, G., 2019. The effect of ferrous ions on hydraulic
conductivity in fine tailings. Engineering Geology, 260, p.105243.