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Mercury Flow in the Wastes Stream of China

Qingru WU

Tsinghua University

Oct 15, 2020

Air Hg emission trend and cross-media effect

2

Atm

osp

her

ic H

g e

mis

sion

s （

t）

Atmospheric Hg emissions have

shown a downward trend in China.

Improved air Hg emission control led to

the increase of Hg burden in the waste.

ULE: Ultra-low emission

Wu et al., ES&T, 2016; Liu et al., ES&T, 2019 Wen et al., JHM, 2020

ULENon-ULE

75%

87%

0

200

400

600

800

P50 =

0.16 mg/kg

0

100

200

300

400

P50 =

0.33 mg/kg

Hg content of wastes (fly ash)

Non-ULE ULE

PC

Boiler

SCRDust

collector WFGD

ULE retrofit

Fly ash Emission removal

How much of Hg in solid wastes is re-emitted?

3Wu et al., ES&T,2015

Hg would be reemitted to air or

released to water/soil during the

disposal of those waste/byproduct

from air pollution control devices.

Research scope of this study

4

To examine the Hg sources and fate in China

To examine the flow of mercury within and among 8 sectors (31 subsectors)

Fuel

consumption

Coal-fired power plants

Incineration and interment

Municipal solid wastes incinerationCoal-fired industrial boilers

Residential coal combustion Biomass combustion

Other coal combustion Interment

Natural gas combustion

Production activities using Hg

Mercuric chloride catalyst productionOil refining

Vinyl chloride monomer (VCM)

productionOil combustion

Building

materials

production

Iron and steel smelting Thermometer production

Sphygmomanometer productionCement production

Fluorescent lamp production

Nonferrous

metal smelting

Copper smelting Battery production

Lead smelting Dental amalgam production

Zinc smelting

Use of Hg-added products

Use of thermometer

Industrial gold smelting Use of sphygmomanometer

Artisanal and small-scale gold mining Use of fluorescent lamp

Aluminum smelting Use of battery

Hg recovery Hg production from recyclable resources Primary Hg ore mining Primary Hg ore mining

Conceptual framework of mercury flow analysis

5Hui et al., ES&T, 2017

Hg input (Tier 1) and distribution (Tier 2)

6

Hg input Activity level Hg input factor

Raw materialSample

number

Raw coal 494

Zinc concentrate 381

Lead concentrate 198

Copper concentrate 207

Gold concentrate 26

Limestone 167

Iron concentrate 73

Mercury is inputted embedded in raw

materials or as pure Hg.

National concentrates sampling sites Number of samples

CoalAir

AmmoniaPC Boiler

SCR

ESP/FF

FGD

Stack

Limestone

Bottom Ash Fly Ash Gypsum

Exhausted Flue GasEconomizer

APH

Waste

water

RηSCR+ESP

ηFGD

𝒅𝒇𝒃𝒐𝒕𝒕𝒐𝒎 𝒂𝒔𝒉 = 1 − 𝑅 𝒅𝒇𝒇𝒍𝒚 𝒂𝒔𝒉 = 𝑅 × 1 − 𝜂𝑆𝐶𝑅+𝐸𝑆𝑃𝒅𝒇𝒘𝒂𝒔𝒕𝒆 𝒘𝒂𝒕𝒆𝒓 = 𝑅 × 1 − 𝜂𝑆𝐶𝑅+𝐸𝑆𝑃 × 𝜂𝐹𝐺𝐷 × 𝑎

𝒅𝒇𝒈𝒚𝒑𝒔𝒖𝒎 = 𝑅 × 1 − 𝜂𝑆𝐶𝑅+𝐸𝑆𝑃 × 𝜂𝐹𝐺𝐷 × (1 − 𝑎)

𝒅𝒇𝒇𝒍𝒖𝒆 𝒈𝒂𝒔 = 𝑅 × 1 − 𝜂𝑆𝐶𝑅+𝐸𝑆𝑃 × (1 − 𝜂𝐹𝐺𝐷)

R released rate of PC boiler;𝜼𝑺𝑪𝑹+𝑬𝑺𝑷mercury removal efficiency of SCR and

ESP;𝜼𝑭𝑮𝑫 mercury removal efficiency

of FGD; a the proportion of mercury to

waster waste water

Hg distribution factor are determined by the Hg

removal efficiency of air pollution control devices,

which are obtained from field measurements.

Tier 3: Wastes & byproducts

• How wastes were disposed?

• How was Hg re-distributed during different types of waste

disposal processes?

7

Wastes disposal

8

Over half industrial wastes are re-used or land-filled

Wastes

Municipal wastes

Industrial wastes

Hazardous wastes National List of Hazardous Wastes

Metallurgical industry

Energy industry

Petrochemical industry

Mining industry

Light industry

Other industry

3%3%3%

13%

18%

28%

32%

3%

3%

3%

28%

Land Cement clinker Fly ash bricks

Commodity concrete Building roads

Mineral substances Used in agriculture

3%3%3%

13%

18%

28%

32%

3%

3%

3%

28%

Land Cement clinker Fly ash bricks

Commodity concrete Building roads

Mineral substances Used in agriculture

Disposal of industry wastes

Wastes disposal

9

Wastes

Municipal wastes

Industrial wastes



Energy industry


Mining industry

Light industry

Other industry

0

500

1000

1500

2000

2500

3000

3500

4000

2010 2011 2012 2013 2014

贮存量

处理量

综合利用量

产生量

Stock

Disposal

Reuse

Production

Unit: 10kt

Disposal of hazardous wastes

Wastes disposal

10

Wastes

Municipal wastes

Industrial wastes



Energy industry


Mining industry

Light industry

Other industry

0%

20%

40%

60%

80%

100%

2006 2007 2008 2009 2010 2011 2012

81.8 81.9 82.9 80.2 79.4 76.9 72.6

3.7 2.7 1.7 1.6 1.5 3.3 2.7

14.5 15.4 15.4 18.2 19.2 19.9 24.7

填埋堆肥焚烧Landfill LandfillCompost Incineration

1) Poor landfill site: Significant environmental

pollution

2) Controlled landfill site: Problems on seepage,

leachate treatment, daily cover

3) Advanced landfill site: Standard landfill site,

accounting for more than 20%.

Hg re-distribution during waste disposal (Tier 3)

11

Final fates of Hg consist of six categories:

Hg emissions to air, releases to water, and releases to land

Hg emissions/releases in this study do not consider Hg transportation

across different environmental media through biogeochemical cycling.

Hg exports

The term “export” indicates Hg exported abroad by embedding in Hg-

containing products

Hg stabilization

The term “stabilization” means that Hg is properly treated in an

environmental sound manner.

Hg stocks

The term “stock” implies that Hg is stored in wastes and byproducts

due to the delay of sales or disposal (more than 1 year). Wastes and

products containing Hg are generally sealed-stored. Thus, they are

regarded to have few environmental impacts during the storage period.

However, once these wastes and products are reused, the embedded Hg

will re-enter production activities and cause potential environmental

impacts.

, 1, ,l q l l h q l h

h

r RE RM

The notation r-REl,q indicates Hg re-distribution from

waste/byproduct l to fate q;

RMl stands for Hg embedded in byproduct l;

α is the utilization rate of waste/byproduct l;

βh is the application proportion of treatment process h;

θq×1,l,h is a column vector, whose element θq1,l,h represents the

distribution factor from waste/byproduct l to fate q during

the treatment process h.

Hg re-distribution factors are calculated by

identifying the utilization/disposal method of

wastes/byproducts and Hg distribution during

different utilization/disposal process.

Re-distribution of Hg in fly ash disposal processes for example

12

Hg re-distribution during utilization of fly ash

1)Producing cement clinker 5% stabilized; 95% emitted to air

2)Producing fly ash bricks 7%-40% emitted to air; the rest stabilized

3)Producing commodity concrete 100% stabilized

4)Building roads 100% stabilized

5)Producing mineral substances 5% released to water;

the rest released to land as wastewater treatment residues

6) Used in agriculture 100% released to land

Hg re-distribution factors for fly ash utilization/disposal

Fate Air Water Land Stabilization

Hg re-distribution factor, % 30.0 0.1 38.0 31.9

Hg flows in China

13

Nonferrous metals

Smelting (NMS)

Incineration and

interment

Primary Hg ore

mining

Use of Hg-added

products

Land 651

Stock 795

Stabilization

420

Water 84

Fuel

consumption

Production activities

using Hg

428

265

1019

11 38

83

71

105

8 8

181

92

4137486

222

41

723 53

Hg input 2643

95

790

408

47

26

116

257760

645

35

Unit: t

1

Recovery companyHg

3To Biomass

66*

20

To NMS

Primary

Hg 20

Building materials

production

2

Biomass 3

Export 129**12814

374

Air 633

226

176

170

28

21

10

4

12

19

Hg as impurity

1714Hg ore

926 Hg input: overall situation of motive

Hg in China’s anthropogenic activities. clean energy or scrap metals substitution;

use of recycled Hg; reducing the production

and use of Hg-added products.

Emission and Release: Direct

environmental impact:,51.8%end-of-pipe Hg control;

increasing controlled landfills and

strengthening solid waste recycling

Safely disposed: 15.8%

Stock: Potential environmental impact,

depending on the disposal/utilization

methods

Atmospheric Hg emissions

14

0.32%1.58%4.42%

16.11%

19.91%

21.96%

35.7% Fuel consumption

Building materials production

Nonferrous metal smelting

Secondary emissions



Primary Hg mining

0.32%4.42%

1.58%

Hg re-emissions from waste reuse

15

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)

0

5

10

15

20

25

30

Atm

osp

her

ic H

g e

mis

sions

(t)

Emissions sources

(1) Recovery of zinc oxidize in zinc smelters

(2) Wastes disposal in cement plants

(3) Disposal of waste Hg-added products

(4) Disposal of smelting slags in zinc smelters

(5) Production of recycled Hg

(6) Fly ash used for bricks production

(7) Acid slags roasting in zinc smelters

(8) Flue gas desulfurization gypsum used for wallboard production

(9) Acid slags roasting in lead smelters

(10) Smelting slags disposal in copper smelters

(11) Acid slags roasting in copper smelters

(12) Disposal of smelting slags in lead smelters

About 102 t of Hg is emitted due to the use of

wastes/byproducts. Recovery of zinc oxide in

zinc smelters and wastes disposal in cement

plants contribute to 26% and 25% of total

secondary atmospheric Hg emissions.

If solid wastes containing Hg are treated

through high temperature, we should

either remove Hg from solid wastes before

the treatment or strengthen Hg reduction

of APCDs for treatment procedures. This

is especially important for solid wastes

disposal in zinc smelting and cement

plants.

Hg release to water and land

16



Fuel consumption


Primary Hg mining

1.20%4.82%

13.25%

31.33%

49.40%



Fuel consumption


Primary Hg mining

1.20%4.82%

13.25%

31.33%

49.40%

0.15%1.08%5.41%

12.83%

13.6%

14.68%17.93%

34.31%



Primary Hg mining


Fuel consumption



Hg recovery

0.15%5.41%1.08%

0.15%1.08%5.41%

12.83%

13.6%

14.68%17.93%

34.31%



Primary Hg mining


Fuel consumption



Hg recovery

0.15%5.41%1.08%

0.15%1.08%5.41%

12.83%

13.6%

14.68%17.93%

34.31%



Primary Hg mining


Fuel consumption



Hg recovery

0.15%5.41%1.08%

34.31%

Water Land

Hg stocks in wastes/products

17

Subsectors Hg stocks (t) Waste/product types

Hg recovery 374

Hg-containing catalysts, waste activated

carbon

Zinc smelting 310

Waste acid sludge, waste water treatment

sludge, calomel

Lead smelting 40


sludge

Fluorescent lamp

production 40Fluorescent lamp

Copper smelting 18

Waste acid sludge, arsenic slag, waste water

treatment sludge

Dental amalgam

production 7 Dental amalgam

LGSP 7


sludge, arsenic slag

Wastes stored in the Hg

recovery companies and

zinc smelters can be used

as Hg recovery materials.

Utilization/disposal of these

wastes in a environmental

sound manner will reduce

potential emissions/releases

Challenges for Hg waste management

Around 651 t Hg released to land, which proposes environmental risks. Around 795 t Hg

stored in the wastes, which proposes big challenge for waste treatment/disposal.

Information gaps: No information system on the production, transfer, recycle, and

disposal of Hg-containing waste.

The system of waste sorting, collection and recycling is still in its infancy.

Current comprehensive utilization of solid wastes can reduce Hg releases to land, but

lead to Hg re-emissions to air.

Limit values for mercury containing waste are not set. Technical guidelines on mercury

waste management in environmentally sound manners not set.

18

References

• Hui M L, Wu Q R, Wang S X, Liang S, Zhang L, Wang F Y, Lenzen M, Wang Y F, Xu L X, Lin Z T, Yang H, Lin Y, Larssen T, Xu M, Hao J M. Mercury flows in China and global drivers. Environ Sci Technol, 2017, 51: 222-231.

• Wu Q R, Wang S X, Li G L, Liang S, Lin C-J, Wang Y F, Cai S Y, Liu K Y, Hao J M. Temporal trend and spatial distribution of speciated atmospheric mercury emissions in China during 1978–2014. Environ Sci Technol, 2016, 50(24): 13428-13435.

• Wu Q R, Wang S X, Hui M L, Wang F Y, Zhang L, Duan L, Luo Y. New insight into atmospheric mercury emissions from zinc smelters using mass flow analysis. Environ Sci Technol, 2015, 49(6): 3532-3539.

• Liu K Y, Wu Q R, Wang L, Wang S X, Liu T H, Ding D, Tang Y, Li G L, Tian H Z, Duan L, Wang X, Fu X W, Feng X B, Hao J M. Measure-specific effectiveness of air pollution control on China's atmospheric mercury concentration and deposition during 2013-2017. Environ Sci Technol, 2019, 53(15): 8938-8946.

• Wen M, Wu Q, Li G, Wang S, Li Z, Tang Y, Xu L, Liu T. Impact of ultra-low emission technology retrofit on the mercury emissions and cross-media transfer in coal-fired power plants. J Hazard Mater, 2020, 396: 1-8.

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Thank you for your attention!

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