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Design, construction and management of tailings storage facilities for surface disposal in China: Case studies of failures


Abstract and Figures

Rapid development of China's economy demands for more mineral resources. At the same time, a vast quantity of mine tailings, as the waste byproduct of mining and mineral processing, is being produced in huge proportions. Tailings impoundments play an important role in the practical surface disposal of these large quantities of mining waste. Historically, tailings were relatively small in quantity and had no commercial value, thus little attention was paid to their disposal. The tailings were preferably discharged near the mines and few tailings storage facilities were constructed in mainland China. This situation has significantly changed since 2000, because the Chinese economy is growing rapidly and Chinese regulations and legislation require that tailings disposal systems must be ready before the mining operation begins. Consequently, data up to 2008 shows that more than 12 000 tailings storage facilities have been built in China. This paper reviews the history of tailings disposal in China, discusses three cases of tailings dam failures and explores failure mechanisms, and the procedures commonly used in China for planning, design, construction and management of tailings impoundments. This paper also discusses the current situation, shortcomings and key weaknesses, as well as future development trends for tailings storage facilities in China.
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Waste Management & Research
31(1) 106 –112
© The Author(s) 2013
Reprints and permission:
DOI: 10.1177/0734242X12462281
China is currently one of the world leaders in both exploitation
and consumption of mineral resources. Billions of tonnes of
metal ores are mined in China every year, and billion of tonnes of
tailings and wastes as byproducts are disposed of on the ground.
In the early 1980s, tailings were considered as residue with no
commercial value. Most of the small and medium-size mines
directly discharged their tailings into the local valleys or rivers
close to the mines. Consequently the mining industry developed
a poor reputation for waste disposal management. With the
enhancement of environmental protection awareness, both regu-
lations and legislation were successively promulgated and imple-
mented in the early 1990s, requiring mine owners to build tailings
disposal facilities and water treatment systems before any com-
mercial mining may commence. The impoundments are regarded
as a major part of the mining facilities and were used to store
tailings and waste water from mineral processing (Kanagasbai
1980; Kwak et al., 2005). With the growth of the mining industry
in China, many tailings impoundments have been built and more
are planned. Up to now, China has achieved success in tailings
disposal and has greatly improved its environmental performance
in relation to mining activities. The authors consider that this
experience and the lessons learned by China’s mine operators
may also be useful to mine operators in other countries. Herein,
the history of tailings disposal in China is discussed and three
examples of tailings dam failures in China are analysed in detail.
The procedures of planning, design and construction of tailings
Design, construction and management
of tailings storage facilities for
surface disposal in China: case
studies of failures
Zuoan Wei1,3,4, Guangzhi Yin1,3,4, J G Wang2, Ling Wan1,4
and Guangzhi Li1,4
Rapid development of China’s economy demands for more mineral resources. At the same time, a vast quantity of mine tailings,
as the waste byproduct of mining and mineral processing, is being produced in huge proportions. Tailings impoundments
play an important role in the practical surface disposal of these large quantities of mining waste. Historically, tailings
were relatively small in quantity and had no commercial value, thus little attention was paid to their disposal. The tailings
were preferably discharged near the mines and few tailings storage facilities were constructed in mainland China. This
situation has significantly changed since 2000, because the Chinese economy is growing rapidly and Chinese regulations
and legislation require that tailings disposal systems must be ready before the mining operation begins. Consequently, data
up to 2008 shows that more than 12 000 tailings storage facilities have been built in China. This paper reviews the history of
tailings disposal in China, discusses three cases of tailings dam failures and explores failure mechanisms, and the procedures
commonly used in China for planning, design, construction and management of tailings impoundments. This paper also
discusses the current situation, shortcomings and key weaknesses, as well as future development trends for tailings storage
facilities in China.
Tailings disposal, tailings management, tailings dam failures, environmental hazards, China tailings dams
1 State Key Laboratory of Coal Mine Disaster Dynamics and Control,
Chongqing University, Chongqing, China
2 School of Mechanical and Chemical Engineering, The University of
Western Australia, Crawley, Western Australia, Australia
3 State and Local Joint Engineering Laboratory of Methane Drainage
in Complex Coal Gas Seam, Chongqing University, Chongqing, China
4 College of Resource and Environmental Science, Chongqing
University, Chongqing, China
Corresponding author:
Zuoan Wei, State Key Laboratory of Coal Mine Disaster Dynamics
and Control, Chongqing University, No. 174 Shapingba Zhengjie,
Chongqing, 400030, China.
462281WMR31110.1177/0734242X12462281Waste Management & ResearchWei et al.
Short Report
Wei et al. 107
impoundments in China are also discussed. Finally the current
situation, key weaknesses, and future development trends for
tailings storage facilities in China are presented.
History of tailings disposal
From 1949 to the present day, the history of tailings disposal in
China can be divided into the following four major phases.
Prior to 1958, mainland China had a few mines and the pro-
duction of minerals by milling was relatively small in quantity.
For example, the steel production in 1949 was only about
158 000 tonnes per year. Such a low production only required a
small amount of mine resources and thus the disposal of the tail-
ings was not considered as a problem.
Between 1958 and 1978, the national mining industry started
a phase of new development and growth. In 1958, the Chinese
government launched a campaign of increased steel-making,
requesting that steel and iron production achieved 10 700 000
tonnes per year. At that time only a few ore mines, such as Hainan
iron ore mine, Anshan iron ore mine, and Yunnan tin mine were
either planned or operating in the whole country. These were
small and medium-sized state-owned mines. During this period,
mineral processing technology was poorly developed and the
production of mineral milling was relatively small. Only some
medium-size mines built specific tailings storage facilities. Most
of the mines had no tailings disposal facilities due to poor envi-
ronmental protection awareness. Their tailings were directly dis-
charged into valleys or rivers near the mines. This situation did
not change much until the late 1980s.
From 1978 to 2000, the number of tailings disposal facilities
steadily increased, and the mine environment slowly changed.
The Chinese government promulgated the first Environmental
Protection Law in 1989 and relevant regulations in 1996, respec-
tively. According to these legislative codes, all mines must con-
struct tailings ponds otherwise the mine may be closed by local
government. Since then the quantity of tailings ponds has dra-
matically increased, reaching more than 6000 by the year 2000.
The planning, construction and operation of tailings storage facil-
ities has become an increasingly important issue for miners.
From 2000 to the present, the mining industry has developed
rapidly along with the rapid economic development within China.
The quantities of tailings discharged from mines also increased
considerably. Data show that there were more than 12 000
tailings ponds up to 2008 (Yin et al., 2011). With the increase of
the number of tailings ponds, some disastrous failures of tailings
dams have occasionally occurred. Consequently the issue of
safety of tailings ponds has become an increasing concern for
both local residents and governments.
Three examples of failure of tailing
dams in China
In conjunction with increased mineral production a number of tail-
ings dam failures have occurred in China since 1960. These fail-
ures have had significantly adverse socioeconomic consequences,
resulting in the loss of many lives, property damage and serious
pollution problems in downstream areas. The earliest documented
failure of a tailings dam took place in Yunnan province in 1962. At
that time, people did not fully appreciate the consequences of tail-
ings dam failures. Communications across the country were also
weak and sharing of information on failures was relatively poor.
Many small tailings dam failures were neither recorded nor
reported. Table 1 summarizes the main failures of tailings dams
that have occurred in China. From these limited records, three typi-
cal cases are analysed below.
Huogudu tin tailings pond, Yunnan
Huogudu tailings pond was owned by the Yunnan Tin Company
and located near Gejiu, a city in Yunnan province. This tailings
pond was designed in June 1956, constructed in July 1957, and
commissioned in August 1958. The pond was in a valley and the
tailings dam was built by the upstream method. At approximately
0230 to 0300 h on 26 September 1962, the main tailings dam rup-
tured after 3 days of moderate rainfall (see Figure 1). The breach
width was about 113 m on the top and 45 m at the bottom and its
depth was about 14 m. At the time of failure, the pond stored about
5.42 × 106 m3 tailings and the tailings dam reached 19.0 m in
height and 441.0 m in length. The failure released approximately
3.30 × 106 m3 of tailings and 3.8 × 105 m3 of water into down-
stream areas. The tailings flowed as far as 4.5 km from the dam
site. The tailings and water destroyed 11 villages, causing 171
deaths and 92 injuries, and rendered 13 970 persons homeless.
After the event, a forensic analysis was carried out by a specialist
team of professionals. The analysis revealed that the intense
Table 1. Main failures of tailings dams in China.
Name of dam Type of tailings Method of construction Year of failure Consequences of failure
Huogudu, Yunnan Tin Group Co., Yunnan Tin Upstream 1962 171 killed
Niujiaolong, Shizhuyuan Non-ferrous
Metals Co., Hunan
Copper Upstream 1985 49 killed
Longjiaoshan, Daye Iron Ore mine, Hubei Iron Upstream 1994 31 killed
Dachang, Nandan Tin mine, Guangxi Tin Upstream 2000 28 killed
Zhenan Gold mine, Shanxi Gold Upstream 2006 17 killed
Xiangfen tailings pond, Shanxi province Iron Upstream 2008 277 killed
108 Waste Management & Research 31(1)
rainfall was the direct cause of the failure, and the lack of experi-
ence in pond management was identified as an indirect cause.
Niujiaolong tailings pond, Hunan province
Niujiaolong tailings pond was owned by Shizhuyuan Zinc Mine
Company and located in a valley near the mine site. The tailings
dam was constructed by the upstream method. The system of tail-
ings ponds was commissioned in 1971 and the design operational
lifetime was 13 years. At that time the design height was 57 m,
and the design capacity was 2.15 × 106 m3.
A typhoon caused heavy rainstorms at the mine from 22 to 24
August 1985. In the early morning of 25 August the strong rain-
storms triggered some flash flooding and mud-debris flows
around the mine area. The debris flowed down the mountain and
entered into the Niujiaolong tailings pond from locations 1# to
5#, as shown in Figure 2. The debris flows forced the pond water
to overtop the tailings dam resulting in failure. At the time of
failure the tailings pond stored about 1.1 × 106 m3 tailings to a
height of 40 m. This failure released approximately 7.3 × 105 m3
tailings. The tailings flowed as far as 4.2 km from the dam site,
destroyed many houses, caused 49 deaths, and resulted in about
US$ 1.6 × 106 in direct losses. The failure also resulted in signifi-
cant pollution of the affected area. The cause of failure was
mainly attributed to meteorological conditions.
Xiangfen tailings pond, Shanxi province
Xiangfen tailings pond was built in a valley near an iron ore mine
in 1977. At that time, the iron ore mine was owned by a large
state-owned steel company. With the mining industry downturn
in the 1980s, the mine was shut down and tailings deposition was
suspended. In 2005, this mine was reopened by a local private
company. In September 2007, the tailings pond was illegally
reused by this company. Due to lack of proper tailings pond man-
agement, the tailings pond was simultaneously used for tailings
depositions and as a water reservoir for the concentrator mill. The
pond was also used to hold extracted groundwater.
At 0758 h on 8 September 2008 the tailings dam failed. At
that time, the tailings pond held about 2.9 × 105 m3 tailings
Figure 1. Plan view of Huogudu tailings pond.
Figure 2. Plan view of Niujiaolong tailings pond.
Wei et al. 109
and the dam was 50.7 m high. This failure released approxi-
mately 1.9 × 105 m3 tailings. The tailings flowed as far as 2.5 km
downstream and covered about 35 hectares of land. Figure 3
shows a photograph at the failure and a sketch of the extent of
the tailings slurry. The tailings destroyed many houses, caused
277 deaths, 33 injuries, and caused about US$ 1.3 × 107 in
direct losses. The failure also resulted in very serious social
The failure was mainly attributed to poor impoundment
management. First, in order to store more tailings, the slope of
the dam wall was built to a vertical (V): horizontal (H) ratio of
V 1 : H 1.4 (see Figure 4(a) and (b)) after the pond was ille-
gally reused, which is significantly steeper than the V 1 : H 4.0
to V 1 : H 5.0 as required by the applicable technical stand-
ards. Second, this tailings pond was incorrectly used as a
water reservoir to store water for the concentrator mill with
the supernatant pond kept at a high level. This combination
produced a relatively short tailings bench and a high phreatic
surface (Figure 4(b)) and resulted in significant seepage
through the dam wall. Finally, a loess wall 4.0 m wide was
built on the tailings dam wall (see Figure 4 (c)) in an attempt
to solve seepage and slope stability problems. The fine loess
material reduced seepage but this resulted in the saturation
zone inside the dam continually extending with the rising
water level, with a corresponding reduction in dam stability.
The tailings dam eventually failed under these worsening con-
ditions (see Figure 4(d)). This failure was therefore due to
human factors.
Cause analysis of tailings dam failures
In China, over 95% of tailings pond incidents occurred in opera-
tions. Tailings dam failures rarely occurred in abandoned or inac-
tive tailings ponds. Accidents were normally triggered by either
natural or human factors. Investigations show that the most com-
mon cause of tailings dam failure is related to heavy rainfall or
snowmelt events. Engineering design did not have a demon-
strated capability to cope with extreme-event climatic conditions
because of a lack of climatic data. This is despite a flood capacity
assessment being undertaken during design. Consequently, the
ponds did not have enough volume to store the flood water from
the surrounding areas and tailings dam failures occurred.
The second important cause is related to human factors, such
as poor design and construction of initial dyke and drainage cul-
verts, or poor management and inadequate maintenance activities
at the tailings dam sites. For example, the cause of failure of the
Shuanghe vanadium mine tailings pond in Shanxi province in
2008 was due to failure of the drainage culvert under the tailings
dam. This accident caused 3000 m3 tailings and waste water to
flow into downstream rivers. Illegal and extended use of tailings
ponds by some private miners are also a common human cause
for failures. Table 2 summarizes the proportional distributions of
the causes of tailings dam failures.
Procedure of design and construction
of tailings ponds
Prior to 1990, China was relatively lacking in technical standards
and guidelines for tailings storage facilities. Design, construc-
tion, and subsequent operational management of tailings ponds
were essentially carried out according to conventional water stor-
age specifications and experiences. In 1990, the first specific
design standard for tailings disposal, termed the Code for Design
of Tailings Disposal Facilities of Concentration Plant (ZBJ1-90),
was promulgated and implementation began in January 1991.
Since then, the design level of tailings ponds has been greatly
improved with the increasing number of tailings ponds built. By
March of 2006, a standard for safety management of tailings
ponds, termed the Safety Technical Regulations for the Tailings
Pond (AQ 2006-2005), was promulgated and implemented.
These safety regulations provide guidance to mine owners on
how to safely and environmentally manage tailings facilities.
Currently mine owners select professional design firms for tail-
ings dam design to ensure project success. The design procedure
is divided into the three main steps listed here, based on the
1. Collect data and information. The information mainly com-
prises the capacity per year of the concentration plant, ore
type, processing type, tailings characteristics, local meteoro-
logical and hydrological data for the mine, and so on.
2. Determine the site of tailings pond. Several possible sites are
chosen based on a topographic map of the mine area. Then
each possible site is evaluated based on field investigations,
Figure 3. Failure of Xiangfen tailings dam: (a) picture of the
tailings pond after failure; (b) sketch plan of the tailings slurry
flowing downstream.
110 Waste Management & Research 31(1)
analysis and calculations. Their advantages and disadvan-
tages are assessed to determine the most suitable site.
3. Produce drawings and documents describing the tailings disposal
facility. After the site of the tailings pond is determined, the pri-
mary design document is formed by the design firm according to
related national standards. The primary design is then examined
officially by a specialist group organized by the local government
and detailed construction drawings are created by the design firm.
At this step, two most important calculations have to be carried
out according to the ZBJ1-90: the stability analysis of the tailings
dam, in which the limit equilibrium method is recommended, and
the flood control capacity analysis (maximum probable flood) of
tailings pond and drainage system.
Once all the construction drawings of the tailings pond have been
completed, tenders or bids are requested from the mine owner to
select a construction company for the project construction. The
construction project typically includes the starter dyke, transportation
system of the tailings slurry from the mill to the pond, the drainage
system of the pond and other facilities. Once the construction project
is completed and officially credited, the project is handed over to the
mine owner. The project starts the operation and the mine owner
takes responsibility for the project management and operation.
Based on Chinese laws, the design firm and the construction
company must have their professional licences and certificates
for design and construction of tailings storage facilities.
Otherwise, these facilities are illegal and companies may be pros-
ecuted under law.
Current situation and further
development in China
Characteristics of tailings ponds
At the end of 2008, there were 12 655 tailings ponds in China.
Their distribution is summarized in Table 3, and their character-
istics are summarized in the following list.
1. The quantity of tailings ponds is very large and widely dis-
tributed across China. Only a few provinces such as Shanghai
and Tianjin do not have tailings ponds. About 200 additional
tailings ponds are constructed each year (Yin et al., 2004).
2. Most tailings ponds are small in size. Among all the tailings
ponds, 12 122 tailings ponds are classified as small,
accounting for 95.8% of the total volume. In this context
small represents less than 60 m in dam height. Furthermore,
over 60% of the tailings dams are less than 10-30 m in
height. Most of these small tailings ponds belong to private
3. Ninety-five percent of the tailings dams were constructed by
the upstream method, the simplest and most economical con-
struction method that is generally available. Unfortunately,
these tailings dams are also inherently weaker and less stable
than those dams constructed using other methods.
Main issues for safety enhancement
Although great advances have been made in the safety manage-
ment of tailings ponds, the following issues in design, construction
and management of tailings ponds still require improvement.
1. Outdated technology and poor management. The upstream
method is the oldest construction method and still the main
Figure 4. Construction procedure of tailings dam and failure
model: (a) the section of the tailings dam not reused until
2005; (b) the section of the tailings dam after reuse in 2007; (c)
the section of the tailings dam before the failure; (d) the failure
caused sliding.
Table 2. Statistical distribution of tailings dam failure causes
in China.
Main causes of dam failure Rate (%)
Start dyke seepage 5.1
Raised dyke break 9.0
Slope seepage 14.1
Drainage facilities damage 28.2
Flood overtopping/overflow 25.6
Dam slope instability 1.3
Landslide around tailings pond 14.1
Seismic liquefaction 2.6
Wei et al. 111
method for tailings dam construction in China. The only
design technical standard of tailings disposal (ZBJ 1-90) has
not been revised since it was implemented in 1990. Most of
the operators at the site are unskilled workers and most mines
are lacking professional advice or good tailings pond man-
agement. These situations frequently lead to accidents.
2. The equipment and technology for the safety monitoring of
tailings pond are of low standard and lag behind the current
development of the mining industry. Up to now, most tailings
dam safety management is based on experience due to lack of
effective monitoring tools. In some mines, monitoring facili-
ties were not of sufficient accuracy to act as an effective
3. Backfilling of underground mines is limited necessitating
storage of large volumes of tailings ponds and dams.
Future development
Statistically tailings ponds are one of the main sources of risk for
the mining industry. The safe management of tailings facilities is
of increasing concern for both local governments and local com-
munities. Consequently technical standards for design, construc-
tion and management of tailings ponds require urgent revision.
The government and the national societies of mines should
increase investment to support application research and technical
innovation in line with the rate of increase in mining. At present,
the following main development trends are envisaged.
Table 3. Distribution of tailings ponds in mainland China (in 2008).
No. Province Total tailings ponds Active Inactive Closed Constructing
1 Jiangsu 19 13 0 5 1
2 Beijing 37 9 0 28 0
3 Qinghai 57 10 44 1 2
4 Heilongjiang 62 45 3 0 14
5 Zhejiang 78 44 8 25 1
6 Xinjiang 103 47 0 11 45
7 Sichuan 137 87 6 7 37
8 Jilin 167 112 2 22 31
9 Gansu 183 107 24 8 44
10 Guizhou 219 103 36 50 30
11 Guangdong 226 63 101 47 15
12 Hubei 236 54 149 3 30
13 Fujian 247 136 0 36 75
14 Shanxi 269 125 25 49 70
15 Anhui 341 263 6 27 45
16 Jiangxi 380 234 45 26 75
17 Shandong 494 252 25 136 81
18 Guangxi 504 184 136 116 68
19 Hunan 651 356 109 160 26
20 Henan 681 275 281 5 120
21 Inner Mongolia 685 449 118 14 104
22 Yunnan 692 457 54 104 77
23 Liaoning 1475 1091 90 120 174
24 Shanxi 1735 602 247 330 556
25 Hebei 2888 1773 343 614 158
1. Strengthen the application of research and technical innova-
tion. It is suggested that the centerline construction method
be considered for use. Some new methods such as the rein-
forced terraced fields method (RTFM) (Wei et al., 2006;
2008) can be also used. Furthermore, the government and
related agencies should carry out new research on engineered
tailings disposal, such as thickened discharge, paste fill, fil-
tered tailings and dry stacking. This may result in new depo-
sition methods and eliminate the need for tailings ponds.
2. Enhance safety management. The emphasis should be put on
pre-failure prevention rather than post-failure repair (Rico
et al., 2008a; 2008b).
3. Reutilization of tailings. For example, tailings can be reused
to produce building materials. This also prolongs the life of
storage facilities.
Conclusions and recommendation
Currently China has more than 12 000 tailings ponds, 95% of
which use the upstream method to construct their tailings dam.
The small size tailings ponds account for 95.8%, and most of
these belong to private miners. Whereas the design and construc-
tion of tailings storage facilities are in accordance with Chinese
regulations the level of operational management is lower in com-
parison with developed countries. This results in most of the tail-
ings ponds having one or more deficiencies. Monitoring
technology for tailings dam is also relatively poor. Although
112 Waste Management & Research 31(1)
assessment of flood capacity of the tailings impoundment is
undertaken during design, floods due to extreme climatic condi-
tions remain a direct cause of tailings dam failures. Another
direct cause of tailings dam failures is the low level of operation
management and lack of professional advice. The future develop-
ment trend is to carry out new engineering research and innova-
tion for tailings disposal, such as thickened discharge, paste fill,
filtered tailings and dry stack, as well as increased reutilization of
The authors are very grateful to Dr Allen L. Li (URS Australia Pty
Ltd., Australia) and Dr Shen Jiayi and anonymous reviewers for their
very useful comments and reviews.
This research has been funded by the National Natural Science
Foundation of China (No. 51074199).
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... The mechanical law of tailings flow is quite complicated, involving multiple interdisciplinary fields, including fluid mechanics, sediment transport and geological hazards [9,11,12]. Although neither systematic theories nor specific guidelines of tailings flow have been established, current research has progressed on the methods of empirical formula, model test and numerical simulation. ...
... The initial reservoir high was chosen to be 0.1 m. The Herschel-Bulkley model is given by Equation (9) τ = τ 0 + kγ n (9) where τ 0 is the yield shear stress; k is the consistency, γ is the shear rate and n is the flow index. It is a generalised model of the Bingham model for n = 1. ...
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... ∆u 0 was defined for the node located at the top of the fill (Equation (7)). ∆u w can be defined using Equation (8). ...
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A sustainable raw materials (RMs) recovery from waste requires a comprehensive generation and communication of knowledge on project potentials and barriers. However, a standardised procedure to capture sustainability aspects in early project development phases is currently missing. Thus, studies on different RM sources are not directly comparable. In this article, an approach is presented which guides its user through a practical interpretation of on-site exploration data on tailings compliant with the United Nations Framework Classification for Resources (UNFC). The development status of the overall project and the recovery of individual RMs are differentiated. To make the assessment results quickly comparable across different studies, they are summarised in a heat-map-like categorisation matrix. In Part I of this study, it is demonstrated with the case study tailings storage facility Bollrich (Germany) how a tailings mining project can be assessed by means of remote screening. In Part II, it is shown how to develop a project from first on-site exploration to a decision whether to intensify costly on-site exploration. It is concluded that with a UNFC-compliant assessment and classification approach, local sustainability aspects can be identified, and a commonly acceptable solution for different stakeholder perspectives can be derived.
... A tailing pond is formed by the accumulation of tailings discharged from metal and non-metal mines, which has a high potential risk of debris flow (Vick, 1990;Wei et al., 2013). Once a tailing pond is damaged, it will lead to vast environmental pollution along with casualties and property losses (Villavicencio et al., 2014;Martin-Crespo et al., 2015;Santamarina et al., 2019;Chen et al., 2021). ...
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The construction period of most tailing ponds generally lasts for more than 10 years or even decades. During this period, it may be affected by more than one earthquake and is often subjected to vibrations generated by mining activities. The tailings liquefied by earthquakes or vibrations may experience dynamic loads again. Due to the low permeability of tailings, the reconsolidation process of tailings after liquefaction is prolonged. Therefore, changes in the nature of the tailings caused by previous earthquakes will affect the performance of the tailing dam in the subsequent earthquakes. Dynamic triaxial tests and bending element tests were conducted on two kinds of tailings from a copper mine in Southwest China to study this process. The tailing specimens will undergo two consolidation processes and subsequent cyclic loads during the test. The influence of reconsolidation degree, confining pressure, and particle size on the dynamic characteristics and wave velocity of the tailings after liquefaction under cyclic loading was measured. The results show that the reconsolidation degree significantly affects the trend of the excess pore water pressure ratio changing with the increase in the cycle number of loads. The reconsolidation process after liquefaction of tailings will improve its liquefaction resistance. The relationship between the ratio of the cycle number of liquefaction after reconsolidation to the cycle number of first liquefaction and the reconsolidation degree is proposed. In the entire experimental process, the shear wave velocity of the tailings gradually decreases when applying the cyclic load and gradually increases during the consolidation process, including the first consolidation before cyclic loading and reconsolidation after liquefaction. The research results are of great significance to the safe disposal of tailings, especially those in earthquake-prone areas.
... This construction approach differs from the one used for water-retaining dams, which are completely built before becoming operational. Most of the tailings dams were built several decades ago and about 45% have been constructed with the upstream method, which is considered the least stable among the tailings dam construction methods (Wei et al., 2013). ...
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Tailings dams are commonly built incrementally to increase the storage capacity of the Tailings Storage Facility (TSF), usually without interrupting the mining activities. Dam management practices, lack of knowledge on tailings behaviour and the poor performance of monitoring and management processes have resulted in disastrous tailings dam failures with human and economic losses, as well as huge environmental consequences to ecosystems and local communities. In the literature, correlation analyses have been carried out considering different variables: stored volume, released volume, runout distance, dam height, peak discharge. Several databases of tailings dam failure are available online, each with different levels of detail. This paper looks at the statistics of tailings dam failures using an up-to-date database on failures and a catalogue of existing TSF. This paper verifies the existing correlations between stored and released volumes using a larger database. The new proposed regression analysis considers the functional relationship between released volume and characteristics of the dam such as height and stored volume (i.e., dam factor). The effect of construction type, fill material and failure mode on the released volume has also been evaluated as well as the frequency of tailings dam failure as function of the construction method. Tailing dams built using the upstream construction method turn out to be more prone to failure, and more susceptible to static and dynamic liquefaction. The new correlation provides more reliable estimates of the expected released volume as a function of dam height and stored volume and should prove useful for runout analyses and risk assessment of tailings dam failure. Finally, the analyses carried out show that there is no correlation between the water pond extension and the released volume.
The high-value utilization of sulfate-rich tailings (SRCTs) can accelerate their mass consumption, so the many problems caused by the massive accumulation of SRCTs can be alleviated, such as environmental pollution, land occupation, security risk, etc. This study proposes using SRCTs to replace fine natural aggregates in MgO-activated slag materials (MASMs) and investigate the influence of the sulfur content in SRCTs on the properties of MASMs. The experimental results showed that the 28 d compressive strength of MASM mortars was increased by up to 83% using SRCT composites. Two major mechanisms were discovered: additional hydration product formation and pore structure refinement. The results of XRD suggested that incorporating SRCT composite into MASMs increased the production of expansive sulfate-containing hydration products, such as ettringite, gypsum, and hydroxyl-Afm. The results of element mapping showed that the oxidation of pyrite in SRCTs could release sulfates into the surrounding area and participate in the hydration of MASM, indicating that SRCTs can work as an auxiliary activator for MASMs. Furthermore, the addition of SRCT significantly refined the pore structure of MASMs, leading to the reduction in porosity by up to 37.77%. These findings confirm a synergistic effect on activating the slag between SRCTs and MgO, promoting the mass utilization of SRCTs. As a result, the additional expansive hydration products contribute to the enhanced compressive strength and refined pore structure.
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In the research on environmental hydraulics, its turbulence and sediment transport, constant challenges have been faced. The complexity of hydraulic impacts towards sediment morphology and turbulent flow properties makes research in this area a difficult task. However, due to pressure from climate change and the mounting issue of pollution, environmental flow studies are more crucial than ever. Bedforming within rivers is a complex process that can be influenced by the hydraulics, vegetated field, and various suspended and bedload transports. Changes in flow conditions due to rain and flood can further complicate a hydraulic system. To date, the turbulence, morphologic, and bedforming characteristics of natural environmental flows are still not well understood. This book aims to bring together a collection of state-of-the-art research and technologies to form a useful guide for the related research and engineering communities. It is useful for authorities and researchers interested in environmental and civil engineering studies, as well as for river and water engineers to understand the current state-of-the-art practices in environmental flow modelling, measurement and management. It is also a good resource for research, post-, or undergraduate students who wish to know about the most up-to-date knowledge in this field.
In recent years, the safety of tailings pond has become a common concern by the local communities and governments. The stability of tailings dam can be increased by improving the mechanical properties of tailings. With the development of chemistry and chemical technologies, the stabilization of soil using polymer has become one of the hotspots in geotechnical engineering. However, few publications focus on studying the mechanical properties of polymer-treated tailings. In this paper, the polyacrylamide, sodium carboxymethyl cellulose, polyvinyl alcohol, and calcium lignosulfonate were used to improve the mechanical properties of tailings. And, the mechanical properties and microstructural characteristics of polymer-treated tailings were investigated. The direct shear test results show that the polyacrylamide has the best performance on improving the mechanical properties of tailings among the four polymers. The mechanical properties of polyacrylamide-treated tailings tend to be stable after 7 days of curing. With the increase of the polyacrylamide content, the shear strength of tailings increases. The cohesion increases first and then tends to be stable. The internal friction angle decreases first and then increases. When the polyacrylamide content is 0.3%, the triaxial compression test results show that the values of cohesion of tailings (tailings clay, tailings silt, and tailings sand) increase by 21.43 ~ 99.34%. The values of internal friction angles of tailings clay and tailings silt increase by 0.87 ~ 2.34%. But, the value of internal friction angle of tailings sand decreases by 3.77%. The SEM images and CT results show that the small particles are adsorbed together by polyacrylamide to form aggregate. The polyacrylamide can also form membrane structures on the surface of particles. These lead to the internal structure of polyacrylamide-treated tailings that is more uniform and dense.
The nonuniformity of samples in reinforcement treatment is a bottleneck that restricts the development of microbial geotechnical technologies, which severely affects the reinforcement effect of microbially reinforced tailings and other fine-grained geotechnical materials. This study presents a mixing method that represents an innovative sample preparation and grouting technology for reinforcing tailings using microbially induced calcite precipitation (MICP) based on the characteristics of tailings discharged in the form of mud and accumulated layer-by-layer. A large number of mechanical experiments and microanalyses were conducted to compare the effects of various methods on tailings reinforcement, including the methods of adding bacterial solution (i.e., the traditional grouting method and the proposed mixing method) and the treatment methods of cementing solution (i.e., the grouting method and soaking). The results of the shear test showed that the strength of the samples generated by the mixing method increased compared with the original tailings samples and samples generated using the traditional grouting method. Moreover, miniature cone penetration test results showed that the samples made using the mixing method had better uniformity, which could be attributed to the fine particles (silt and clay particles) of tailings that strongly adsorb bacteria and the low permeability of the fine particle tailings, which is not conducive to the spread of bacteria. In the tailings samples, the traditional grouting method only makes the bacteria gather at the region where the bacterial solution initially makes contact. However, the mixing method evenly distributed the bacteria among the tailings particles, which significantly improved the reinforcement effect of bacteria, as the reinforcement reaction occurred throughout each region of the samples. Therefore, the mixing method can be used for reinforcement research and in the application of MICP to tailings or other fine-grained geotechnical materials.
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A detailed search and re-evaluation of the known historical cases of tailings dam failure was carried out. A corpus of 147 cases of worldwide tailings dam disasters, from which 26 located in Europe, was compiled in a database. This contains six sections, including dam location, its physical and constructive characteristics, actual and putative failure cause, sludge hydrodynamics, socio-economical consequences and environmental impacts. Europe ranks in second place in reported accidents (18%), more than one third of them in dams 10-20 m high. In Europe, the most common cause of failure is related to unusual rain, whereas there is a lack of occurrences associated with seismic liquefaction, which is the second cause of tailings dam breakage elsewhere in the world. Moreover, over 90% of incidents occurred in active mines, and only 10% refer to abandoned ponds. The results reached by this preliminary analysis show an urgent need for EU regulations regarding technical standards of tailings disposal.
Surface disposition of mine tailings in paste form is a new disposal technique, and to achieve a desired depositional geometry, it is necessary to characterize the paste's flow properties. This study investigates how water content affects the flow behaviour and depositional geometry of tailings and kaolinite pastes, which are shear-thinning, high solids content, mineral pastes. A stress-controlled rheometer and a strain-controlled viscometer with vane fixtures were used to characterize the yield behaviour of the pastes, and three types of yield stress were determined. A flume apparatus was used to simulate paste deposition under laboratory conditions. The depositional angle, determined from the flume tests, and the yield stresses, determined from the rheometers, decreased as the water content increased. For each type of yield stress, a linear relationship was found between the depositional angle and the Sofra–Boger dimensionless group (τy′Fr/Re), with the linear coefficient depending on paste type.
The upstream method is a popular method for raising tailings dams. Currently in China there are more than 12,000 tailings impoundments and almost 95% of them use the upstream method for the construction of the dam. Statistical data has shown that the tailings impoundment is one of the main sources of risk in the mining industry. Failures of tailings impoundments have resulted in the loss of many lives, considerable property damage, and irreversible pollution in downstream areas. Therefore, the safety of tailings management facilities has been of increasing concern to governments and local communities. The management of a conventional tailings storage facility requires the maintenance of a high level of structural stability. Therefore, according to the relevant mine Acts, the mine operators are required to conduct stability analyses for all types of tailings facilities, whether they are new, active, or decommissioned. For the stability analysis of tailings dams, the accurate profile of the tailings dam is very important. The profiles are easily obtained for both active and decommissioned tailings facilities because their data can be collected through field investigations. However, collecting basic data from newly constructed tailings facilities is difficult. In this paper, a laboratory physical model test has been performed. The construction process for new tailings impoundment has been physically simulated in the laboratory, where the tailings particle composition and distribution below a beach, the change of phreatic surface of the dam, and the engineering properties of the tailings of the dam profiles have been measured. A new tailings facility, Yangtianqin tailings impoundment, owned by Tongchang copper mine of Yuxi Mine Co., was used as a case study to illustrate the physical modeling of the tailings dam. In the model test, the geometrical model of pond area was constructed according to the scale factor, λL, of 1:200 (model:prototype), and the tailings discharge system was also established, the tailings slurry then being discharged based on the design data. Finally, on the basis of the model test results on profiles, the stability analysis of the tailings dam at different heights was conducted under different conditions. The model test results and stability analysis show that the height of the tailings dam should be less than that originally planned. The original design of Yangtianqing tailings impoundment should therefore be revised for the safety of the tailings impoundment.
A characteristic common to most tailings dam failures is that the mine tailings tend to liquefy and flow over substantial distances, with potential for extensive damage to property and life. In order to be able to assess the potential for damage in case of such failure, it is necessary to be able to predict the characteristics of the flow and the possible extent of flood movement. This paper presents analytical procedures for making such evaluations. The behavior of tailings materials during flow is represented by a Bingham plastic rheological model in these analysis procedures. It is apparent from the analyses that the flow of phosphate tailings would be expected to be turbulent but flows for other types of tailings would be expected to be laminar. The procedures described are applicable for flow of tailings on horizontal and sloping planes and in prismatic valleys. The analyses can be performed using dimensionless charts in the case of flow on planes, and a computer program in the case of flow in prismatic valleys.
New mining technologies can exploit low-grade ores but they produce high volumes of waste, such as tailings. Further, current mineral processing techniques produce more and more fine tailings. How to dispose of these tailings is a key issue in the sustainable operation of a mine. A traditional method is to construct a settling or tailings pond for storage. Such a method requires sufficient coarse particles to raise a dam or embankment. However, the fine tailings contain little coarse particles and have poor mechanical properties. The stability of a tailings dam thus becomes a major issue if the traditional method is used. According to statistical data, all fine tailings dams or ponds in China have failed or have failure potential. Therefore, fine tailings disposal is a challenge to mine operators and new disposal methods should be explored for the stability improvement of tailings dams. In this paper, an innovative method of reinforced terraced fields is presented to satisfy the specific requirement of fine tailings disposal. By using an actual mine, this paper reports in detail the design concept and procedures for this method. Its feasibility is evaluated and its fundamental are analyzed.
Thesis (Ph. D.)--University of California, Berkeley, 1980. Includes bibliographical references (leaves 247-256). "8113085." Photocopy.
This paper compiles the available information on historic tailings dam failures with the purpose to establish simple correlations between tailings ponds geometric parameters (e.g., dam height, tailings volume) and the hydraulic characteristics of floods resulting from released tailings. Following the collapse of a mining waste dam, only a part of tailings and polluted water stored at the dam is released, and this outflow volume is difficult to estimate prior the incident. In this study, tailings' volume stored at the time of failure was shown to have a good correlation (r2=0.86) with the tailings outflow volume, and the volume of spilled tailings was correlated with its run-out distance (r2=0.57). An envelope curve was drawn encompassing the majority of data points indicating the potential maximum downstream distance affected by a tailings' spill. The application of the described regression equations for prediction purposes needs to be treated with caution and with support of on-site measurement and observations. However, they may provide a universal baseline approximation on tailing outflow characteristics (even if detailed dam information is unavailable), which is of a great importance for risk analysis purposes.
Fine Tailings and its Dam Stability Analysis
  • G Yin
  • Z Wei
  • J Xu
Yin G, Wei Z and Xu J (2004) Fine Tailings and its Dam Stability Analysis. Chongqing, China: Chongqing University Publishing House, pp. 1-4 [in Chinese].
The Reinforcement Terraced Fields Method
  • Wei Z Li
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  • Liu
  • Zhao
Wei Z, Li SH, Liu X and Zhao Y (2006) The Reinforcement Terraced Fields Method. Chinese patent (No. 200610075635.3).
The Reinforcement Terraced Fields Method
  • Z Wei
  • S H Li
  • X Liu
  • Y Zhao
Wei Z, Li SH, Liu X and Zhao Y (2006) The Reinforcement Terraced Fields Method. Chinese patent (No. 200610075635.3).