John Kline – John Kline Consulting

Robert Schreiber Jr. – Schreiber, Yonley & Associates

April 2013

Presentation

Background

Sources of Mercury

Mercury Oxidation

Typical Emissions

Internal Cycles

Mass Balances

Conclusions

NESHAP Rules Reissued

Pollutant Existing Sources New Sources EPA expected

Emissions

Reductions

Mercury 55 lb/million tons

clinker

21 lbs/million tons

clinker

93%

THC 24 ppmvd 24 ppmvd 82%

O-HAP 12 ppmvd 12 ppmvd

PM 0.07 lb/ton clinker 0.02 lb/ton clinker 91%

HCL 3 ppmvd 3 ppmvd 96%

Compliance Date September 2015

Knowledge comes from coal

And Slag

Input

Outputs

Output

Source - Tutorial: Mercury Chemistry in Boilers and Mercury Control Technology (Part 1), C. Senior, April

17-21, 2005 30th International Technical Conference on Coal Utilization & Fuel Systems, Clearwater,

Florida

But, Cement is Very Different

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

Kiln Feed

Fuels From

Kiln &

Precalciner

Raw Mill

BH Catch

Stack

Coal

Mill

1000 oC

330 oC

90 oC

Fuel Sources

Mean Values 0.035 – 0.095

Raw Materials

0.001

0.01

0.1

1

Limestone Clay Shale Sand Flyash Bottom Ash

Mill Scale

Me

rcu

ry C

on

cen

tra

tio

ns

in

PP

M

Min

Max

Mean

And materials can vary over time

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

Mercury oxidation occurs

Influencing

Factors

Temperature

Cl Available

O Available

SO3 Available

Typical Cement Kiln Emissions

Schreiber & Kellett 2009

Mercury Speciation – Long Wet

Mercury Speciation – Long Dry

Schreiber & Kellett 2009

Good

Generalization

but each case is

specific

Mercury Speciation – Summary

Schreiber & Kellett 2009

Internal Cycles

Raw mill

Can capture 90% of mercury emissions

Captured mercury tends to be oxidized

Coal mill

Captures mercury if using preheater gases

Complete internal cycle until disruption

Baghouse

Can capture a large amount of mercury

Dust removal can be effective bleed

Large internal cycles

Mercury in the Cement Industry, commissioned by Cembureau – CSI (April 2010)

Raw

Meal

BH

Dust

Scale

Change

Mercury Emissions Mill On / Off

Schreiber & Kellett 2009

Mass Balances

Periodic / Average value mass balances

Give a good overall picture

Can take into effect longer term variations in

fuels and raw materials

Spot Balances

Give a view of what is happening at the

moment

Allows identification of internal cycles

Annual Mass Balance Tons/hr PPM Hg Lbs Hg/hr

Limestone 136 1.02 0.292

Shale 20 0.01 0.037

Clay 16 0.23 0.008

Iron 5 0.00 0.000

Total Feed 174 0.90 0.3370.000

Fuel 13 0.02 0.0010.000

Total Input 0.338

Clinker 117 0.02 0.005

Hours ug Hg/DSCM Lbs Hg/hr

Mill On 6,245 241 0.094

Mill Off 1,207 2197 0.162

Stack Total 0.2560.000

Total Output 0.260

Balance 77%

Mercury Cycles

0%

100%

200%

300%

400%

500%

600%

700%

800%

900%

1000%

Raw Coal As Fired Fuel

Raw Mill Feed

Kiln Feed Preheater Exit

Raw Mill Product

CKD Stack

Plant A Mill On

Plant A Mill Off

Plant B Mill On

Plant C Mill On

Plant D Mill On

Plant E Averaged

Spot Balance Particle Gaseous

DRY TPH ppm lbs/hr Bound lbs/h lbs/hr

Inputs

Kiln Feed 122.4 3.016 0.813 0.813

Mix fuel (as fired) 6.8 2.996 0.045 0.045

Tires (as fired) 0.4 0.168 0.000 0.000

CFS (as fired) 1.4 0.586 0.002 0.002

Coarse coke 0.000 0.000

Coal fines 0.001 0.001

Raw Mill Feed Rate 121.0 2.425 0.646 0.646

Total In 0.646 0.860

Outputs

Raw Mill Product 119.6 3.145 0.828 0.828

Out of Filter in CKD 8.4 13.988 0.260 0.260

Stack Oxidized 0.166

Stack Elemental 0.217

Coke Mill Product 9.4 1.676 0.035 0.035

Coke Mill Stack 0.000

Total Out 1.123 0.383

Spot Balance

Calculated Measured

ug/DNCM ug/DNCM

Oxidized Hg+ 394 400

Elemental Hg0 517 525

Total HgT 911 925

Balance 98%

53% Oxidized captured in raw mill from kiln gas

57% Oxidized captured in Filter

98% Oxidized & elemental captured in coal mill

Spot Balance

OutputsInputs

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

1400.0

1600.0

8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00

Fuel Kiln Feed Mill Feed Mill Product CKD Stack

Raw Mill Feeder Choke

0.0

100.0

200.0

300.0

400.0

500.0

600.0

700.0

800.0

900.0

In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out

8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00

Spot Balance

Conclusions

Cement plants are more complex and

more variable than power plants

Mercury input varies according to the

raw materials and fuels used

Mercury levels vary even within a

specific raw material or fuel over time

Mercury oxidation is important to control

strategies and needs to be better

understood

Conclusions

Modern cement plants have up to 3 internal cycles

In-line raw mills

Fuel processing using preheater gases

Return dust from exhaust gas filters

Global and spot balances should be performed over several time periods to better understand the mercury cycles

Do not purchase your abatement technology until you understand your cycles