Ash Grove Durkee & PC MA
Goals of Meeting

• Durkee plant emissions• Need for Subcategorization

– Technical rationale for doing so

• Hg control technologies

– What works

– What doesn’t

• Next steps – What additional information do

need to make a technically and legally sound

decision?
Durkee History

• Sept/Dec 2006 extensive mercury stack testi

• April and May 2007 ACI pilot testing

• Sept 2007 ODEQ Stakeholders first met

• Dec 2007 ODEQ issued stakeholder report

• March 2008 Public Meeting on Order

• July 2008 Order signed by ODEQ

• Feb 2009 Construction initiated on ACI system

• April 2010 Complete sorbent trap installation

• Startup ACI system by July 2010

• Significant reductions will be in place 3 years 
Sources of Mercury at Durk

• Hg in cement plants comes from:

– Materials quarried on site

• Primarily limestone

• ~99% of Durkee Hg

– Fuels

• ~1% of Durkee Hg

– Additives imported from off‐site

• e.g., power plant fly ash (not used by Ash Grove)

• ~0% at Durkee

• Estimated 2007 emissions: 2,163 lbs Hg• Estimated 2008 emissions: 1,508 lbs Hg• About 2,670 pounds per million tons of clinker

Enhanced ACI Recirculation Syst

Hg0 Scrubber

Heat Exchanger

Heated Area (800°F)

Carbon

Carbon Storage Tank

Hg laden exhaust (266°F/412°F)

Carbon

Clean gas

Carbon/Raw Material Bleed

MA

I

NSTACK

Hg CMS

Hg CMS

ACI Baghouse

Make up carbon

Inert Gas + 

Hg vapor

Inert Gas (N2) Makeup

Air lock
Mercury Considerations

• Hg levels in limestone vary widely

– Durkee monthly average limestone ranges 

424 ppb to 1,740 ppb

• Samples gathered between 2006 and 2009

• Hg forms vary widely

– Elemental Hg can account for more than h

total Hg

• Hg concentrates in system
y = 2.089x + 135.67

R2 = 0.4337

y = 2.

R

-

100200300400500600

- 10.00 20.00 30.00 40.00 50.00 60.00 70.0

Time, hours

ug/dscm

Elemental HgTotal Hg

Hg CEM Data (Raw Mill On)
Mercury Transformation

• Oxidized Hg captured in raw mill and re

kiln as component of kiln feed

• Feed at top of tower (800oF) volatilizes 

primarily elemental form

• Amount and rate of conversion to oxidi

form determined by gas conditions in t

with subsequent recapture by raw mill
Ash Grove Research

• 1 month pilot study

• Hg control (relative)

Mercury 

Type

Raw Mill 

On

Raw Mill 

Off

% C

Raw 

O

Elemental 209.2 354.5 40.

Oxidized 214.6 2752.8 92.

Total 423.9 3107.3 86.

ug/dscm ug/dscm
Ash Grove Commitment

• Ash Grove signed Order with Oregon DEQ 

2008

– Requires by July 2010:

• Minimum 75% Hg control

• All reasonable efforts to remove 85% of Hg

– Would decrease Hg emissions to:

• 670 lb/MM ton clinker at 75% control

• 400 lb/MM ton clinker at 85% control

– Controls in construction

• Will remove about 2.8 tons of Hg before NESHAP 

standards require any reduction

– Assuming 2007 production/emission levels
Portland Cement MACT Prop

• EPA recognized Durkee controls as “the 

control technology currently available s

as is known”

– EPA recognized that importing limestone i

impractical for plants like Durkee

– Means Durkee must rely on controls

– ACI will not reach 43 lb/MM ton clinker

• Would require 99% SRE

• Based on the pilot test results, EERC and ODEQ

stakeholder committee recommended 75% co
Construction Underway on Durkee ACI Sys
Durkee Carbon Trap Syste
• Tectonic activit

• Created belt wthere is enhanced history• Geothermal acindication of Hg

Why is Oregon Limestone Differ
50

75

100125150

Net U.S. Cement Supply Balance (million metric tonnes)

Source: Portland Cement Association

U.S. cement supply is already predicted to be un

meet future demand even without plant closure

Green 

Red = U
Global Cement Manufacturing:

•2.75 billion tons per year, with majority in 

expanding developing nations, primarily C•Worldwide demand for cement is predicte

to 80% in the next 20 years

Western U.S. demand that cannot be met domeswill be satisfied by imports from Asia
Existing Pacific Cement Imp

Infrastructure

 Pacific Coast has 

strong population and economic growth and cement supply imbalance.

 None of the 

planned plant modernizations is for Pacific coastal region, due to role and threat of imports.
Imported Cement Results 

Greater Emissions

• Environ study found that cement impor

from China to California has ~50% grea

emissions than domestic cement

– Study assumed that Chinese and U.S. cem

plants are equally efficient and equally we

controlled

• These may not be rational assumptions

– Difference in emissions attributable solely 

electricity usage and moving cement from plant to U.S. port
Emissions From Cement Imp

• Emissions of pollutants such as SO2, PM

NOx also higher for imported cement

• Ships bringing cement from Pacific Rim countr

bunker fuel with up to 5% sulfur

– Average sulfur content in cargo ship fuel = 27,000 

– U.S. trucks cannot use diesel with more than 15 pp

• Ships burn fuel with over 1,800 times more su

gallon than allowed in fuel used by a U.S. truc

• Ship fuel has much higher nitrogen con

resulting in more NOx emissions

• SO2 and NOx result in more PM2.5 emiss
Unintended Consequences of 

Providing a Technical Option

• Durkee plant provides:

– 116 direct jobs in Baker County

• Six different union lodges represent hourly wo

• >$9,000,000 per year payroll and benefits

– Numerous indirect jobs

• Operating budget is in excess of $40,000,000

• Capital budget normally exceeds $3,000,000 a

– ~$1 million/year in property taxes– Substantial contributor to local causes
Solution: >225 ppb Subcateg

• Clean Air Act allows EPA to create

subcategories with different standards:

– “The Administrator may distinguish among classe

and sizes of sources within a category or subcate

establishing such standards...” Clean Air Act § 11

– “The concurring opinion in Brick MACT supports

subcategorization in situations involving sources’dependence on high‐HAP raw materials to avoid 

where a level of performance achieved by some s

proves unachievable by other sources even afterapplication of best technological controls, viewinsources as of a different type than others in the scategory.” EPA Preamble to Proposed Rule (p.21
Subcategorization Accords W

Common Sense

• Brick MACT decision:

“one legitimate basis for creating additional

subcategories must be the interest in keepin

relation between ‘achieved’ and ‘achievable’ accord with common sense and the reasonab

meaning of the statute.”
Subcategorization Accords W

Clean Air Act

• Congress clearly stated that EPA should 

require substitution of mined feedstock

setting NESHAP standards [Conf. CommReport]:

“the substitution of cleaner ore stocks was noevent,

a feasible basis on which to set emissio

standards...[where] metallic impurity levels ar

and unpredictable both from mine to mine an

specific ore deposits.”

– This quote sums up limestone quarries
MACT is NOT Intended to Shut Down So

Congress’ intent in relation to subcategorizat

similarly made clear in the House Report asso

with the 1990 Amendments. The House Rep

states that:

“ The Committee expects MACT to be meaningful, s

MACT will require substantial reductions in emissuncontrolled levels. However, MACT is not inten

require unsafe control measures, or to drive southe brink of shut down.” House Rep. No. 101‐49

at 328 (May 17, 1990) (emphasis added).
Subcategorization

• Subcategorization for sources with >225 ppb

limestone

• Floor based on current, uncontrolled emissio

the two plants in subcategory

• EPA could then impose

a “beyond the floor”

standard

– Technology based limit

– Work practices

• Total reductions at Durkee will be subst

and could reach as high as 90%

– 90% control

= 267 lb/MM ton clinker
Beyond the Floor Technolo

• ACI

– Best technology for addressing mix of Hg 

• Wet scrubber does not work for elemental Hg

– Only technology that works for arid areas

• Tehachapi and Durkee in very arid areas

• Annual rainfall in Durkee is ~8 inches so wet s

not technically feasible
Beyond the Floor Technolo

• ACI

– Require 75% minimum SRE

• SRE standard appropriate for beyond the floo

technology

– Technology may outperform this level

• Too uncertain to set standard at 85% SRE

– Solution: Require Control Enhancement Ac

Plan

• Ash Grove committed to all reasonable measu

reach 85% control
Beyond the Floor Work Pract

• Minimize Hg entering system

– Require Mercury Minimization Plan

• Identify and minimize Hg in off‐site mat

– Prohibit use of fly ash in raw feed

• Not currently used by Durkee
Dust Shuttling

• Ash Grove recognizes benefits of maxim

dust shuttling (aka, raw meal purge)

– Wasting baghouse dust not appropriate– Shuttling baghouse dust to finish mill has g

promise

– Cannot be required above levels where pr

product specification would not be met

• Creates quality issues if overused
What are the Specific Restrictions to Dust Shu

Most DOTs do not support ASTM C1157 Cements. Florida, Oregon,

Washington, Idaho, and Nevada do not allow C1157 cements for DOT proj

only allows C1157 for road base.

There are Four National Cement Specifications

Portland CemePortland CemeType IP and IS 

ASTM C150 AASHTO M-85 ASTM C595 Blended 

Insoluble Residue 0.75%, Max 0.75%, Max IP = no limit, IS = 1% LOI, limit 3.00% 3.00% IP = 5% max, IS = 3.0% Limestone Addition 5% Max 5% Max Not defined Process Additions 5% Max 5% Max No limit, Use C465 comparisons 
Action Items from February 11, 2009 Meeting with FDE

Cement Industry, Consultants (Dr. Greg Miller), and 

The focus was to discuss the options available to the Cement In

limit mercury (Hg) emitted during the clinkering process.

Meeting Action Items:

• “Cement industry to try and utilize filter dust back into the cem

product.”

• “FDOT will assist with testing the ‘new’ cement to verifying com

with M‐85. The Department has agreed that the filter dust is o

long as the cement continues to comply with AASHTO M‐ 85.”

• “Once the new cement is available, the FDOT will conduct test

durability tests in hopes that the high alkali, high Hg cement is 

deleterious to our concrete or reinforcing steel.”

• “DEP indicated that the new restrictions on Hg emissions have 

deployment date of March 31, 2009. However the standards m

implemented prior to or after this intended implementation da
2005 Portland Cement Shipme

Information from USGS 2005 Minerals Yearbook
Dust Shuttling

• AASHTO and ASTM standards allow up 

inorganic processing additions

• Cement must still meet other specs

– Insoluble residue: ≤ 0.75 percent

– Loss on ignition: ≤ 3.0 percent

– Limestone addition: ≤ 5 percent

• Based on CO2 content

– Process addition: ≤ 5 percent

• Extensive debate as to what this will tra

to at any individual plant
Mercury Reduction Patent

• Heidelberg’s patent application

– German (only) patent pending (Feb 2007)

• Taiheiyo Cement Co filed patent application filed in J

(Sept 2004)

• Ash Grove filed patent application in US (March 200

• Status

– Patents pending– Protective filings– Technical details are sparse

– Not yet demonstrated in long term practice and no capture

efficiencies claimed

– European and Japanese cement standards are different th
Dust Shuttling at Durkee

• Baghouse dust has calcium carbonate so it w

as limestone and the maximum addition rate 

• At 5% addition rate the insoluble residue is 1

– BH dust has 20% silica and a IR of about 18%

– Maximum dust is 2.14% to achieve 0.70 IR

• BH dust is 35% LOI so adding 4% would raise 

cement with 1% LOI to 2.5% LOI

• Insoluble residue limits BH dust addition to 
Durkee Baghouse Dust

Concentration During Pilot T
Durkee’s Maximum Addition 

• Clinker produced – 900,000 tons

• Clinker shipped to grinding operation – 300,000 tons

• Cement produced at Durkee with clinker and gypsum

630,000 tons

• Dust shuttled at 2.14% – 13, 482 tons or 2.0 tph whe

mill is running.

• Potential mercury reduction is 404 pounds or 15%

• This leaves 2223 pounds left to reduce to meet the p

standard or

a 98.1% reduction

• We can’t but WHAT if we could reduce it by 30%?

– 1819 pounds to reduce to meet the proposed standard or

reduction
Question?

How many control technologies installed 

cement plant can achieve 98% control o

monthly rolling averaging period?
Dust Shuttling

• Degree of benefits not clear

– Lehigh believes it could reach 30% SRE at 

Bridge plant

• Union Bridge baghouse dust averages 25 ppm 

during raw mill down conditions

• Result of high relative percentage of oxidized 

• Union Bridge shows higher Hg concentration i

baghouse dust than other Lehigh plants

(From e‐mail Tim Matz to Keith Barnett)
Dust Shuttling

• Tehachapi data suggesting Union Bridg

control efficiency is not transferrable

– Tehachapi: Vast majority of Hg is element

baghouse dust Hg concentrations typically 

ppm

– Tehachapi Hg concentration in raw feed is 

of Union Bridge

– Tehachapi Hg concentration in baghouse 

40% of Union Bridge

(From e‐mail Tim Matz to Keith Barnett)
Dust Shuttling Conclusion

• Dust shuttling clearly holds great prom

• Degree of benefit varies with site‐speci

characteristics

– Not all variables fully understood

• Percentage of baghouse dust that can b

in finish mill can be defined by objectiv

• Percentage of baghouse dust that can b

in finish mill will vary plant to plant
Dust Shuttling Conclusion

• In light of uncertainty, don’t lose track 

– Work practice requiring maximum reducti

rather than a specified emission rate

• Require use of dust shuttling

– Up to limit of what can be accomplished w

impairing cement’s ability to meet quality

standards

• Require documentation of shuttling

maximization
Other Suggested Technolog

• Selective Quarrying• SCR• Limestone scrubbing• CKD treatment ‐ Roasting????
Selective Mining

• Some commenters suggested possibilit

selective mining to avoid Hg in raw feed

• Extensive Ash Grove research at Durkee

quarry

• Variability in Hg concentration through

quarry

– No means of predicting areas of high

concentration
What Causes Variability?

• Plate tectonic movement has disrupted origin

position and composition of rocks through fo

fracturing, igneous activity and metamorphis

• Secondary structures such as fractures, faults

folds caused by plate movement created pref

pathways for geothermal fluids and gases to

infiltrate original host rock

• Geothermal activity associated with mineral d

such as Hg

Durkee Quarry Geology

• Geologically Complex

– Limestone deposits have undergone

extreme deformation since first depo

• Severely folded, fractured and faulted• Multiple faults with significant stratigra

offsets

• Lack of stratigraphic continuity

–Quarry is in an area of an active

hydrothermal vent
Main Limestone Quarry

Quarry Bench Faces ‐ Nelson Marble

Bench 1

Bench 2

Bench 3

Typically 45’ Thick
Mercury Distribution in Qua

• Bench blasts from 2006‐2009 have bee

correlated to Hg distribution

– Unpredictable distribution across benches

– Unpredictable distribution within individu

(3895’ map)

– 2006‐2009 bench blast map exhibits check

distribution of Hg concentrations
Mercury Distribution With Blast Layo
● Tremendous Hg variation 

within just a few feet● Not predictable so cannot be mined around
Selective Mining Conclusio

• Hg concentrations not predictable

– Range from 424 ppb to 1,740 ppb

• Not practical to mine around Hg as it ha

identifiable pockets

• Lowest value found in quarry is still out of range 

plants

• DC Circuit previously stated ore switc

not a “predictable and consistent con

strategy” [Copper Smelter MACT dec
Additional Control Options Rais

Comments

• Serial wet scrubber

– Same issue as primary wet scrubber: No water

– Wet scrubber does not work on the elemental Hg 

the challenge for ACI

• CEM & stack test data show high levels of elemental Hg

• Oxidation Techniques

– SCR

• We know of no evidence it enhances Hg conversion to 

form any better than ACI

– EERC tried several exotic carbons at Durkee
Full scale ACI Test at Durkee Show Captu

of Oxidized and Elemental are Simil

AGCC Du May 10, 2007

0

500

10001500

2000250030003500400045005000

0:000:452:553:404:305:156:006:457:358:209:059:5710:4211:2712:2013:0513:5014:3515:2516:1016:5517:4018:3019:1520:0021:2522:10

Time hh:mm

TOTAL 

Hg ug/Nm3 @ 7% O2

TotalAve TotalElementalAve Ele.RM Status Ave Elemental Hg: 266 ug RM Down

Ave Elemental Hg: 90 ug with PAC = 66% reductionAve Total Hg: 2715 ug RM DownAve Total Hg: 1129 ug with PAC = 58% reduction

Raw Mill Off

PAC Injection On
Additional Control Options Raised in Com

Mercury Roaster

The information contained or referenced in this presentation is confidential and proprietary to

FLSmidth and is protected by copyright or trade secret laws.

Mercury Roaster

Baghouse

dust

Quench Quench

Sorbent

To stack

To

finish 

mill

Clean

Dust

to silo

Calcium

chloride

Heat source

(bypass,

Cooler, HGG)

Key points• Will not conthan Durkee because we t

gas stream• Increases hconsumption 

emissions• May be go

smaller reducrequired
Best Beyond the Floor Packa

• >225 ppb subcategory must install ACI

– 75% minimum SRE

– Implement Control Enhancement Action P

maximize benefits of ACI

• Require all reasonable measures to maximize

performance

• Recurring assessment of whether SRE exceeds 

– Duty to reassess injection rates and other

reasonable measures

• Ensures continuous improvement efforts to r
Best Beyond the Floor Packa

• Reduce Hg entering cycle from offsite

materials

– Require Mercury Minimization Plan

• Prohibit use of fly ash in raw feed• Evaluate and minimize Hg in other imported m

• Require dust shuttling up to maximum 

achievable without impacting product q

– Require site specific evaluation:

• Document maximization of shuttling

• Document optimal timing of dust bleed
Best Beyond the Floor Packa

• Could result in 90%+ SRE

– Until optimized at individual plant, not cle

combination can achieve

– This approach puts emphasis on optimum

possible Hg reduction

– If 90% is achieved, Durkee would be ~267 

Hg/million ton clinker

• Huge reduction• Incremental additional reductions unlikely
Best Beyond the Floor Packa

• This approach enables Ash Grove to:

– Commence Hg control 3 years earlier than 

MACT standards

• About 2.8 tons additional mercury removed

– Employ “the best control technology curre

available so far as is known”

– Employ the only control technology know

effective on all forms of Hg

– Keep jobs in the U.S.– Avoid emissions associated with imported 
Conclusions

• Proposed resolution ensures:

– Protection of environment

– Compliance with Clean Air Act

– Protection of jobs and community

• Avoids offshoring jobs to country’s with poore• If plants such as Durkee & Tehachapi close, th

Western U.S. will meet cement demand throuimports

• What is EPA thinking on approach?

• What addition information does EPA ne

• Next steps
Questions?