remediation of mining legacy sites: chinese practices business dialogue 2017/5... · 9 national...
TRANSCRIPT
11
Qingshan Zhu
Remediation of mining legacy
sites: Chinese Practices
Institute of Process Engineering
Chinese Academy of Sciences
2
1. Introduction
2. Use of mining legacy sites
3. Utilization of gangue and
tailings
Outlines
2
3
1. Introduction
2. Use of mining legacy sites
3. Utilization of gangue and
tailings
Outlines
3
4
(1) Chinese minerals: low grade
Coal: 50% are low-rank coal
1t coal discharges 0.15-0.2t coal gangue
Background
5
(1) Chinese minerals: low grade
Iron ore
1t iron ore concentrate: 2t waste rock+2t tailings
70 billion tons, 95% low grade iron ore
Average Fe 33%, 11% lower than world
average
4036 mines, large mine 28, medium mine
61, 97.8% are small scale mines
Need beneficiation before use
Background
6
(2) Large population, huge mineral consumption
Consumption Domestic production waste/tailings
Iron ore 1.43 0.41 0.87
Coal 3.66 3.40 0.59
Unit: billion ton
Total iron ore gangue/tailings: >10 billion tons, over 4000
iron ore waste rock piles or tailings dams
Total coal gangue:＞5 billion tons, over 1600 coal gangue
piles
Occupied 4 million hectares land
increased 40,000 hectares per year
Background
7
(3) Small agricultural land per capital
Land area: 9.6
million km2; 0.78
hectare per capital,
1/3 of world average
Agricultural land:
0.11 hectare per
capital, 43% of
world average
Background
88
History of mined land reclamation
(1) First stage (1949-1980s)
Almost no land reclamation
(2) Second stage (1988-1998)
“Land reclamation provision (1988)”: government
promotes land reclamation; State investment on research
and demonstration
(3) Third stage (1998-present)
“Land management act” (1998): all damaged land must
be remediated
“Regulations on land reclamation monitoring”
(2007): report on land damage and reclamation plan
“Regulations on land reclamation” (2011): detailed
requirements on the implementation
99
National strategy on land reclamation
All the damaged land must be remediated
(1) New mines
Licence can be obtained before the land reclamation plan
was approved by government
Land reclamation fund must first be established before
issuing the licence
(2) Mines in use
Land reclamation plan and fund need to be established
before renewing the licence
(3) Closed mines
Government initiates to make land reclamation plan and
establish the reclamation fund
1010
Land reclamation in China
(1) Overall mines
9000 large mines, 260,000 medium and small mines
Over 7 billion tons of mining gangue
Over 10 billion tons of tailings, stored on over 3000 tailings
ponds
(2) Overall land reclamation
Land damage due to mining: 4 million hectares
Land reclamation of mining legacy sites: 860,000 hectares,
~20% damaged land was remediated
100,000 hectares land reclamation every year
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1995 2000 2005 2010 2015
120
125
130
135
140
145
Agricultura
l la
nd (
mill
ion h
ecta
re)
Year
Change of agricultural land
2016
Decrease: 336 khm2
due to construction,
industrial and
mining
Increase: 293 khm2
due to reclamation
Decrease rate: from 500 khm2 to 40 khm
2 per year
Land reclamation in China
12
1. Introduction
2. Use of mining legacy sites
3. Utilization of gangue and
tailings
Outlines
12
13
(1) Huangshi national mine park
I. Mine park
Daye iron ore: high grade 54-60%
Start at 254 AC in Han dynasty;
Restart in 1890 for iron ore for
Hanyang Iron factory, provide 3000
t/m iron ore for the first modern iron
company
Up to 1938, produce 6.1 million
tons of iron ore
1938-1945: 9.2 million tons of iron
ore shipped to Japan
1960: 2.90 million t/a of iron ore
1971: 5.05 million t/a of iron ore
1958-2003: 112.61 million tons
iron ore in total
Daye iron ore mine 1930s
Hanyang iron factory 1930s
14
(1) Huangshi national mine park
444m
Closed in 2003
Revegetation area: 2.47106 m2
Total area: 30.2 km2
Open at April 22, 2007
I. Mine park
15
(2) Maoming mine park
Start in 1958, closed in
1992
Produce oil shale oil
100 million tons, which
produce shale oil 2.92
million tons
Mine area 6.8 km2, depth 70 meters, ecological environment deterioration
Ecological remediation started in 2014
I. Mine park
16
(2) Maoming mine park
Plant 13,000 trees, over 100 hectares, new road 25.2 km;
Capacity of reservoir 1600 million m3, irrigating farmland 600 hectares
I. Mine park
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II. Revegetation of mining site
(1) Soil reconstruction
leveling
refilling
Topsoil
Isolation
layer
Vegetation
Gangue
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(2) Plant selection
Festuca arundinacea Clover Vetiver grass
Erect milkvetchLucerne Bermuda grass
II. Revegetation of mining site
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(3) Slop stabilization
II. Revegetation of mining site
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Example 1: iron ore mine (Anshan steel)Established in 1948, produce crude steel 331.93 million tons in 2015
Has 6 iron ore mines, produce 65 million tons raw ore, get 18 million
tons iron ore concentrate
Formed 8 tailings dams (4 still in use) of 1669 hectares, and 8 waste rock
fields of 2094 hectares
II. Revegetation of mining site
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Example 1: iron ore mine (Anshan steel)Reclamation and revegetation start in 2007
II. Revegetation of mining site
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Example 1: iron ore mine (Anshan steel)Pant 6 million trees, 5.8 million bushes
II. Revegetation of mining site
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Example 1: iron ore mine (Anshan steel)Reclamation area: 3000 hectares, reclamation rate 90%; revegetation
rate 95%
II. Revegetation of mining site
25
Example 1: iron ore mine (Anshan steel)Established 3 reclamation demonstration park
II. Revegetation of mining site
26
Example 1: iron ore mine (Anshan steel)
II. Revegetation of mining site
Established 3 reclamation demonstration park
27
Example 2: coal gangue hill (Luan coal Ltd.)
II. Revegetation of mining site
Over 200 coal gangue hills of ~1500 hectares were revegetated all over China
13 coal gangue “hills” (8 still in use), occupied land 67 hectares
5 coal gangue hills of 33.7 hectares revegetated
28
III. Photovoltaic power generation
(1)Xiaoyi subsided coal mine PV projectCapacity 100 MW: Sept. 2014 start to construction, capacity 30 MW,
finished August 2015; second phase 70 MW finished Nov. 2016
Subsided area: 200 hectares
Investment 1 billion RMB, electricity output 140 million kWh
29
(2)Linxiang copper ore tailings pond PV projectCapacity 20 MW: start in July 2015, connected to the grid in June 28,
2016
Covered area: 120 hectares
Investment 180 million RMB, electricity output 19.5 million kWh
III. Photovoltaic power generation
30
(3)Huainan coal mine subsided lake PV projectCapacity 40 MW, 165000 PV module in total, connected to the grid in
June 16, 2017
Subsided lake area: 400 hectares, PV module covered area: 87 hectares
Investment 320 million RMB, electricity output 33 million kWh
III. Photovoltaic power generation
31
(4)Others
Other 10 mine PV projects finished with capacity of 220 MW
Around 20 mine PV projects planned with capacity over 500 MW
III. Photovoltaic power generation
32
1. Introduction
2. Use of mining legacy sites
3. Utilization of gangue and
tailings
Outlines
32
33
I. Coal gangue utilization
1600 coal gangue “hills”, total amount 5 billion tons
increased by 150-200 million tons per year
Land occupation: 13,700 hectares
Utilization ratio increased year by year, currently utilization
ratio ~70%
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Utilization technologies
(1) Thermal utilization (power generation, combustion)
carbon content >20%, calorific value >6200 kJ/kg
(2) Construction materials (bricks)
calorific value 2100-6200 kJ/kg
(3) Filling materials (mine, roads)
calorific value <2100 kJ/kg
(4) Pigments
Special compositionThermal
utilization
Construction
materials
Filling
materials
I. Coal gangue utilization
2013
35
(1) Coal gangue power generation plantsHuanglin mine Guolin power plant
Over 250 coal gangue power plant with total capacity 35
GW, the largest capacity 330 MW
Consume 150 million tons of coal gangue in 2013, 32% of
the total coal gangue discharged in 2013
I. Coal gangue utilization
36
(2) Make construction materials
Over 1000 coal gangue brick plants, produce 13 billion bricks
Consume 56 million tons of coal gangue in 2013, 12% of the
total coal gangue discharged in 2013
I. Coal gangue utilization
37
(3) Filling materials
260 million tons of coal gangue were used to filling and
remediating mines and in 2013, 56% of the total coal gangue
discharged in 2013
I. Coal gangue utilization
38
(4) White pigment from kaolinite coal gangue
Roasting
additives
product
Mixing
Established 30,000t/a kolin white
pigment in 2013
Whiteness 95，particle size: 0.1-5m
Hydrothermal
I. Coal gangue utilization
39
II. Iron ore tailings utilization
Over 2000 iron ore tailings dams, total amount 10 billion tons
increased by 400-600 million tons per year
Iron content (TFe) 10-18%
Low value utilization, most of them are not used
New technology to recovery iron ore concentrate
40
New utilization processIron ore tailings
TFe: 10-18% high gradient magnetic separator
Primary iron ore concentrate
TFe: 30-35%
Magnetizing roasting
Fe2O3+H2Fe3O4+H2O
II. Iron ore tailings utilization
41
New utilization process
Primary iron ore concentrate after roasting
Magnetic
separation
Secondary tailings
TFe 3.5%
Recovery concentrate
TFe 66.5%
Bright phase: Fe3O4; dark phase: silicates
II. Iron ore tailings utilization
42
New utilization processIron ore tailings
TFe: 10-18% high gradient magnetic separator
Primary Iron ore concentrate
TFe: 30-35%
magnetic separatorTFe: 60-66%
II. Iron ore tailings utilization
4343Yunnan Province, China
Shaft FB
（1966)
FB
(2009)
FB
(2013)
capacity(10kt/a) 10 3 5 10
T(C) 850 700 850 500
Time(h) 4 0.5 0.5 0.25
Fe recovery(%) 72 81 81 93
Energy
comsumption
(kgce)102 85 91 68
Fe2O3+H2Fe3O4+H2O
100kt/a technology demonstration plant
II. Iron ore tailings utilization
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6 million (4*1.5 million) t/a plant (Anshan Steel)
28.5 m tons of tailings processed to produce 6.2 m tons primary
iron ore concentrate, after magnetizing roasting-magnetic separation,
2.5 m tons of iron ore concentrate with TFe 66.5%
II. Iron ore tailings utilization
空气
5660.4 Nm3/h, 823K
矿石 15.2 t/h
水 0.76t/h
4519.0 Nm3/h
高炉
煤气 5770 Nm3/h
5660.4 Nm3/h, 823K
1591K
24t H2O
923K
9596.5
Nm3/h
12138.3 Nm3/h
682K
10660.5
Nm3/h
373K
H2O 6 t/h
矿浆
1
2
5
7
8
9
10
17
16
15
13
11
12
14
19
20
21
6
3
4
18
矿石
Fe2O3.1.5H2O 8.9t/h
脉石 6.3 t/h
水 0.76t/h
Fe2O3.H2O 8.5 t/h
SiO2 6.3 t/h
Fe2O3 7.6 t/h
脉石 6.63 t/h
Fe3O4 7.4 t/h
脉石 6.3 t/h
Fe2O3 7.6 t/h
脉石 6.3 t/h
矿石 15.2 t/h
水 0.76t/h
823K
5770 Nm3/h
12138.3 Nm3/h
22
23
23
454K
45
Thank you for your
attention!
46
(1) Soil reconstruction
Acidic gangue
an isolation layer
II. Revegetation of mining site
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Example 3: red mud tailings pond (Pingguo Alumina)
Area: 45 hectares, 5 million tons of red mud
II. Revegetation of mining site
48
Example 3: red mud tailings pond (Pingguo Alumina)
Revegetation area: 70 hectares
II. Revegetation of mining site
49
Example 3: red mud tailings pond (Pingguo Alumina)
II. Revegetation of mining site
Revegetation area: 70 hectares
50
(4)Chengde iron ore tailings pond PV project
Capacity 20 MW: closed in 2014, start to install PV module in June
2016, 77436 PV module in total, connected to the grid in June 29, 2017
Land area: 50.76 hectares
III. Photovoltaic power generation