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MERCURY IN CEMENT. Autor (es): John Kline Charles Kline Compañía: Kline Consulting. Importance of Mercury.

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mercury in cement

MERCURY IN CEMENT

Autor (es): John Kline

Charles Kline

Compañía: Kline Consulting

importance of mercury
Importance of Mercury

The World Health Organization states: “Mercury is recognized as a chemical of globalconcern due to its ability to travel long distances in the atmosphere; its persistence in the environment; its ability to accumulate in ecosystems, including in fish, and its significant negative effect on human health and the environment.”

geneva january 19 2013
Geneva – January 19, 2013

“ Today in the early hours of 19 January 2013 we have closed a chapter on a journey that has taken four years of often intense but ultimately successful negotiations and opened a new chapter towards a sustainable future. This has been done in the name of vulnerable populations everywhere and represents an opportunity for a healthier and more sustainable century for all peoples”.

Fernando Lugris, the Uruguayan chair of the mercury treaty negotiations

139 countries agree legally binding treaty on mercury
139 Countries AgreeLegally Binding Treaty on Mercury

The Minamata Convention Calls for …

“A wide range of controls and reductions across a range of products, processes and industries where mercury is used, released or emitted”

Cement industry is specifically identified

Excerpt from the UNEP Press Release

mercury limits in latam
Mercury Limits in LATAM

* Includes Cd & Hg Source: FICEM

us three new regulations
US - Three New Regulations
  • National Emission Standards for Hazardous Air Pollutants (NESHAP) for the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants
    • Final Rule published on February 13th
  • Commercial and Industrial Solid Waste Incineration Rules (CISWI) also revised for kilns firing solid waste fuels
    • New definition of waste introduced
  • Mercury and Air Toxics Standards (MATS) rule will regulate mercury monitoring and reductions from the US coal and oil fired power industry
    • Final Rule Published on February 16, 2012
european union
European Union
  • EU directive 96/61/EC on Integrated Pollution Prevention and Control (IPPC)
  • Best Available Technology (BAT) and achieving Associated Emission Levels (AELs) below 0.050 mg/Nm3.
  • BAT Reference Document (BREF) for the cement and lime industries that was approved in 2009.
  • Cement kilns are expected to utilize BAT technologies to reduce emission levels however the allowable emission target is somewhat flexible.
earth s crust
Earth’s Crust
  • Average of 50 ppb in earth’s crust
  • Concentrated in areas of volcanic activity
    • Precipitates in new crust HgS(requires pressure and temperature)
      • Historically, cinnabar mined in volcanic areas
    • Released to the atmosphere or surface water, precipitates to background levels, and is ultimately returned to earth’s crust through organic matter (limestone, coal…)
atmospheric mercury deposition
Atmospheric mercury deposition

Wyoming\'s Upper Fremont Glacier over the last 270 years

Note: both local and global influences

slide19

33 %

33 %

33 %

slide21

Cement – 9 %

Plus a portion of

Fossil Fuel for Power

raw materials
Raw Materials

Max

Mercury Concentrations in PPM

Mean

Min

fuel sources
Fuel Sources

Mean Values 0.035 – 0.095

and materials can vary over time
And materials can vary over time

Monthly mass balance Hg contributions by raw material (Linero, Read, and Derosa, 2008)

mercury cycles1
Mercury Cycles
  • Mercury is a volatile element similar to chlorine and alkalis, but with a lower condensation temperature
  • Virtually all the mercury in the kiln system is volatilized before or in the burning zone
  • Virtually all of the mercury leaves the preheater in a gaseous form
  • However, much of that mercury is caught and returned to the system
mercury cycles in cement
Mercury Cycles in Cement

Kiln Feed

330 oC

Stack

1000 oC

Fuels From Kiln & Precalciner

90 oC

Raw Mill

Coal Mill

BH Catch

Source: "Fate and transport of mercury in Portland cement manufacturing facilities", J.K. Sikkema. Theses and Dissertations. Paper 11907. http://lib.dr.iastate.edu/etd/11907

slide29

Mercury Emissions Raw Mill Off + Raw Mill On

Scale Change

Schreiber & Kellett 2009

factors that impact oxidation
Factors that impact oxidation
  • Temperature Profile
    • Time
    • Temperature
  • Level of Oxygen in gas
  • Level of moisture in gas
  • Amount of halogens in gas
    • Cl, F, Br, I
  • Chemicals that interact with halogens
    • K, Na, SO2 / SO3
mercury oxidation occurs
Mercury oxidation occurs

Influencing Factors

Temperature

Cl Available

O Available

SO3 Available

oxidation
Oxidation
  • Oxidized mercury is water soluble
  • Oxidized mercury is easier to capture
  • Oxidized mercury becomes easily particle bound
  • Elemental mercury is none of the above
  • Therefore, we like mercury to be oxidized
slide34

Mercury Emissions Averages All Cement Kilns Surveyed

Good Generalization but each case is specific

Schreiber & Kellett 2009

sorbent trap monitoring systems
Sorbent Trap Monitoring Systems
  • Known volumes of flue is pulled through a sorbent. Vapor phase Hg is collected on the sorbent.
    • Typical sorbent medium is halogenated carbon
    • Paired sorbent traps are used for quality-assurance purposes and to ensure measurement precision
  • A pair of sorbent traps is typically used for 24 to 168, before being removed and analyzed.
  • Less expensive, but only good if emissions are steady
continuous emissions monitors cems
Continuous Emissions Monitors (CEMs)
  • Measure emissions continuously
  • Expensive to install and operate
  • Give a continuous signal, many differentiate between oxidized and elemental
  • Good for investigations and plants with variable emissions patterns
    • In-line raw mills
    • High variability in inputs
slide38

APPROVED CEMS(CEMs)

German UBA - http://www.umweltbundesamt.de/luft/messeinrichtungen/e_quecksilber.pdfUS EPA - http://www.epa.gov/etv/vt-ams.html#mcem

dust wasting 2 35
Dust Wasting (2 – 35%)

Taking the baghouse dust out of the kiln feed

Advantages

  • Low Capex Requirement
  • Dust can often be shuttled to cement
  • Adjustable to needs

Disadvantages

  • Low reduction potential
  • Capture depends on particle bound mercury
  • Can be ineffective when in-line raw mill is off
dust roasting 25 75
Dust Roasting (25 – 75%)

Removing the mercury captured on the dust by heat treating the dust and recapturing the mercury in a concentrated stream

Advantages

  • Can use the dust as raw feed or product
  • Relatively low Capex

Disadvantages

  • Can only roast what is captured, so limited capture
  • Need a sorbent or other system to trap the mercury
  • Hazardous waste to remove from plant
chemical fixers 5 50
Chemical Fixers (5 – 50%)

Chemicals that are added to the gas stream to “fix” mercury, usually as a sulphur compound

Advantages

  • Avoid the issues associated with activated carbon
  • Little Capex required, may be able to use existing equipment

Disadvantages

  • Not proven
  • Chemicals may be expensive
  • Limited temperature range to work within
  • May cause “problems” in cement kilns
wet scrubber systems 5 60
Wet Scrubber Systems (5 – 60%)

Dry Kiln System with SOx Problem

Using a wet scrubber to remove water soluble (oxidized) mercury from the flue gas

Advantages

  • May already be installed or required for SOx control

Disadvantages

  • Capex intensive $50 mn to $250mn +
  • Can only scrub oxidized mercury
  • Need oxidizer system to produce gypsum
  • Can have re-emission of mercury from liquid
    • Typically 20% and will be in elemental form
  • Mercury trapped in liquids will need cleaning
  • Mercury trapped in gypsum, may make it unusable in cement (waste to land fill)
dry sorbent injection 50 90
Dry Sorbent Injection (50 – 90%)

Using a dry sorbent (most likely activated carbon) to capture gaseous emissions

Advantages

  • Low capital costs to install
  • Easy to operate
  • Sorbent rate can be varied according to needs

Disadvantages

  • Baghouse dust must be removed from the kiln feed
  • Sorbent may impact cement properties (air entraining) if dust and sorbent is added to cement
  • Therefore, may require off-site disposal
semi dry scrubber 85 95
Semi Dry Scrubber (85 – 95%)

Using low temperature, sorbents and particle contact to capture Hg in a partial or full exhaust stream.

Advantages

  • Less Capex than FGD (less than half)
  • Can take a partial gas stream
  • Can use multiple sorbents
  • Simpler to operate
  • No waste liquids to treat
  • Solid product maybe usable in cement

Disadvantages

  • Requires a particulate collection device after it
  • Higher Capex than AC and existing / new baghouse
slide46

Estimates of Mercury Capture Efficiency

2 – 35%

2 – 40%

5– 60%

25– 75%

50– 90%

85– 99%

Source: FLSmidth

slide47

Estimated Operating Costs

0% 100% 200% 300% 400%

Mercury Reduction Required

Source Adapted from: Gore, Kolde and Knotts 2012

summary and conclusions
Summary and Conclusions
  • 2013 Will be the year in which mercury emissions will come under a global treaty
  • Many countries are already controlling mercury emissions
  • The cement industry accounts for approximately 9% of the global emissions
  • Mercury measurement and abatement will be coming to the global cement industry
summary and conclusions1
Summary and Conclusions
  • In preparation:
  • Know your mercury balance
    • Measure all inputs on a regular basis
    • The higher the variability the more frequent the testing
  • Confirm your emissions
    • Long wet and dry kilns can use Hg traps
    • Kilns with inline raw mills should use CEMs
summary and conclusions2
Summary and Conclusions
  • Reduce your emissions now
    • Eliminate high Hg inputs (fuel and raw materials)
    • Remove baghouse dust from the kiln feed and add to the cement
    • Consider using oxidizers to enhance mercury capture
  • Plan abatement strategy (<0.05 mg/Nm3)
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