From: Maxwell, Candice A.

To: Maxwell, Candice A.

Subject: FW: Utac L-1 Burner Observations (03/22/12 - 03/23/12 NOx Tests)

Date: Friday, May 04, 2012 1:43:47 PM

Attachments: Table 1 & 2 - Utac L-1 NOX Reduction Test Results 032312.xlsx

Utac L-1 Gas Burner Primary Air Fan Airflows, Summary to Date 032312.xls

Table 14 Utac L-1 Coal Mill Exhauster Fan, Summary Airflow Data and Calcs 032312.xls

From: Suardini, Peter J.

Sent: Friday, May 04, 2012 10:29 AM

To: Gischia, Scott

Cc: Maxwell, Candice A.; mary.gade@yahoo.com

Subject: FW: Utac L-1 Burner Observations (03/22/12 - 03/23/12 NOx Tests)

Scott,

05/04/12 Revisions are in red, provides an update and better understanding to the original e-mails

sent to Candice/Jen.

Thanx for your advise and help.

Pete

From: Suardini, Peter J.

Sent: Tuesday, April 24, 2012 5:24 PM

To: Maxwell, Candice A.; Weidemann, Lisa L.

Cc: Krause, Jennifer A.; Dostal, Thomas C.

Subject: FW: Utac L-1 Burner Observations (03/22/12 - 03/23/12 NOx Tests)

Candice/Lisa/Jen,

Do we want to pass some of the attached data and blue comments (below) on to Aecometrics (as

confidential).

I feel we may want to give them some NOx data/results (at least verbally), if we want them to help us

reduce NOx.

Also see correspondence to date between Jen/Aecometrics (far below).

Trust you will setup internal conf. call to discuss our stategy, followed by Aeco conf. call (I will call in for

both).

I am at Northshore this week, and plan to be at Utac site next Tu/Wd.

Pete

From: Suardini, Peter J.

Sent: Wednesday, March 28, 2012 5:30 PM

To: Krause, Jennifer A.;

Subject: Utac L-1 Burner Observations (03/22/12 - 03/23/12 NOx Tests)

Jen,

Note attachments: Table 1 (03/22/12): Straight Gas Tests, including running coal mill exhauster fan with

cold air (damper closed and open).

· Table 2 (03/23/12): Straight Gas vs. Coal/Gas Mix vs. Straight Coal Tests

· L-1 Gas Burner Primary Air Fan Airflows, pertinent data is in Table 6 (03/22/12) and Table 7

(03/23/12)

· Table 14 contains all the L-1 Coal Mill Airflow Data with Various Burner Tip Sizes (most recent

on the bottom). Whizzer wheel diameter is 80”.

Note that Table 14 also has airflow/pressure projections in “green” if we put slightly longer blades on

the exhauster fan (to increase whizzer wheel diameter to 82-84”).

Main NOx-Related observations I would make are: (Keep in mind that Minntac’s report specified 100%stoich air to their low NOx, kiln gas burner).

I. Table 1 -Straight Gas Tests: 03/22/12, Normal Pellet Production (235 LTPH), High Fuel

Consumption/Rate (189 MCF/hr Gas)

- Opening exhausting damper and venting air from coal mill (with coal mill down) did not

help. Gas and NOx both went up.

- Running coal mill exhauster fan with damper closed-to-open reduced NOx by 30-55%,

with corresponding 5-16% increase in gas consumption.

- Reason for gas increase is 3A damper closed, cooler stack got hotter, and KOG setpoint

had to be raised by operator (to maintain pellet BZ temperatures).

Note that as we ran the coal mill and increased stoich air from 18% to 55% (present max.), the

gas flame bec a me very intense (like a cutting torch when you hit the oxygen!).

II. Table 2 - Gas/Coal Tests : 03/23/12, Lower Pellet Production (200 LTPH), Normal Fuel

Consumption/Rate (150 MCF/hr. Gas)

- Straight gas and straight coal flames looked the best (most concentric), and coal/gas mix

flame seemed to lick the bed more. We still may need/want to do more burner aiming in

the future?

- Starting coal mill (with cold air and no coal), reduced NOx similar to 03/22 test (55-60%),

although we did not allow the gas rate time to restabilize (gas & NOx would have gone

up some).

- Coal/Gas mix (65%/35%) and straight coal also reduced NOx by 55-60% (compared to

straight gas), with coal/gas mix appearing to be lowest NOx.

- Coal/Gas mix (65%/35%) and straight coal appeared to increase fuel consumption by 7-

9% above straight gas (but may need to stabilize longer to better quantify).

- Did not note it, but fuel increase was once again due to 3A damper closing, cooler stack

getting hotter, and the required KOG setpoint increase.

I am sure these measurement will vary with circuit conditions, but wanted to start to

document/quantify NOx reductions and fuel penalties, as we test pushing more combustion air to the

burner.

Note: On 03/22/12, We did not assess any potential pellet quality problems and other circuit

operational issues (such as particulate emissions) caused by running the extra air from the coal mill

when we were on straight gas. The test was not long enough to evaluate those issues, but note that

the pellets leaving the cooler did get significantly hotter. Sometimes, the coal mill will not be

available to run when we are running on straight gas.

Note: On 05/02/12, We tried repeating the Table 1 tests from 03/22/12 (running the coal mill on

straight gas), but had to shut down the coal mill due to decreasing pellet BZ temps, high gas

consumption (about 20% increase, ie., 215 MCF/hr vs. 180 MCF/hr), and pellet fusing in the cooler.

Under those conditions, pellet production rate would have had to be substantially cut to keep running

with the higher burner air rates. Based on these observations, more testing is probably warranted.

A few other items:

· Coal mill airflow was pretty low at 6.0 STPH coal (10,600 ACFM vs. 15,000 ACFM design airflow).

If coal mill operating problems arise/persist, may need to go back to bigger coal burner tip or

longer whizzer wheel blades (we are buying 84” blades).

· Best to free up atomizing & flame shaping orifice adjustment on burner during next down (they

are closed/jammed). Will allow us to increase atomizing & flame shaping airflows even more

(perhaps 7000 ACFM max. instead of present 5000 ACFM max.)

, may further reduce NOx on

straight gas.· Need to keep experimenting with burner and coal mill adjustments. If buildup on coal still

proves unmanageable, we may want to get aiming capability back (and move burner down/right

even more in the back?).

Let me know any comments.

Pete

From: Krause, Jennifer A.

Sent: Tuesday, April 24, 2012 1:11 PM

To: Chris Onysko

Cc: Dostal, Thomas C.; Suardini, Peter J.; Maxwell, Candice A.; Weidemann, Lisa L.

Subject: RE: United Taconite - Kiln Burner

Chris,

Sorry to clarify the Coal Firing 11000-12000 CFM is conveying air

The air we would have on for coal firing would be the shaping air (cooling air) which varies from 30-80%

open on the valve (see airflows listed in previous email). Generally we operate in of the more in 60-80%

Open range on cooling air. This is an automated valve in the field. At times we have run lower cooling

air.

We also keep the atomizing air on at the max flow rate generally but this is done in case we need to

switch gas because the coal goes down. There is no automated valve for atomizing air it is a manual

valve in the field.

Basically the air settings we are operating at is based on the flame shape/appearance. We are still

experimenting with the burner on Line 1. It appears the coal flame looks better when atomizing air is cut

back to 25% valve open range however, this is a problem if we run a low valve setting and we lose the

coal due to atomizing air being a manual valve however, we should probably look at purchasing an

automated valve. Again the requirements for air settings/adjustments have been experimental just

based on visual observation.

For co-firing we would be running around 4- 5 TPH of coal and 1000-1200 CFM of gas but the flame dips

into pellet bed causing more build-up so, we do not do co- firing. We are unable to run lower gas

settings due to our gas valve in field which will be changed out in August.

We would like to gain more information on how to operate the burners to lower emissions (NOX, SOX)

and/or reducing fuel consumption.

Thanks

Jen

From: Chris Onysko [ mailto:COnysko@aecometric.com ]

Sent: Tuesday, April 24, 2012 8:23 AM

To: Krause, Jennifer A.

Subject: RE: United Taconite - Kiln Burner

Hi Jen,

Thank you for getting back with that information. I have a few more questions I would like to clarify:

- You listed the combustion air for coal firing as 11000-12000 CFM. I think there may be a bitof a misunderstanding. I assume that that is the conveying air flow rate, which carries the

coal into the kiln chamber. The combustion air I was referring to would be a separate line

entering the kiln, possibly your “Cooling Fan 1” shown on the PDF you sent. If you could

send a P&ID, showing all process streams entering the kiln, and the flows of each, that

would be very helpful. Additionally, if you could provide the temperature of the combustion

air, this would be useful information

- You mentioned on the phone that you were having problems co-firing the burner on gas

and coal. Could you please provide the flow rates of each that you attempted to fire at,

along with the combustion air flow rate used during co-fire?

- You also mentioned that you were trying to “optimize” the burners. Were there any specific

problems that you are trying to address? It is difficult for us to make suggestions without

knowing what the problems are. Any specifics you could provide with regards to areas you

would like to improve would be helpful

A plant P&ID would be especially helpful, which lists the flow rate of all process streams entering and

exiting the kiln, including combustion air. Please let me know if you can provide this information.

Thank you,



### Chris Onysko

Project Manager

COnysko@aecometric.com

____________________________________________________________________________________________________________

Aecometric Corporation / Conamara Limited

374 Ohio Road

Richmond Hill, Ontario

L4C 2Z9

Tel: (905) 883-9555 x.255

Fax: (905) 883-9578



### www.aecometric.com

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From: Krause, Jennifer A. [ mailto:Jennifer.Krause@CliffsNR.com ]

Sent: April 23, 2012 4:14 PM

To: Chris Onysko

Cc: Suardini, Peter J.; Dostal, Thomas C.; Maxwell, Candice A.; Weidemann, Lisa L.; Ekholm, Corie A.

Subject: RE: United Taconite - Kiln Burner

Chris,

See responses to questions below (shown in red).

We would like to gain more information on how burner adjustments for the Line 1 Burner can affect

emissions (NOX, SOX) and/or fuel consumption for all fuel combinations (straight coal; straight gas;combination of gas and coal). Also, could this information be applied to our Line 2 Conamara gas/fuel oil

burner that was installed in 1988.

Please let me know if any additional information is needed.

Thanks

Jen

From: Chris Onysko [ mailto:COnysko@aecometric.com ]

Sent: Monday, April 23, 2012 12:14 PM

To: Krause, Jennifer A.

Subject: United Taconite - Kiln Burner Emissions

Hello Jennifer,

To follow up with our earlier telephone conversation, I have spoken with our engineering department,

and they would like some more information about the plant operating conditions in order to provide

helpful answers about the NOx levels. Could you please provide the following information:

- What fuel are you firing? Are you co-firing any fuels?

– Primarily firing on straight coal. We

tried mixing with gas but more build-up was generated in Kiln. Basically running either

straight coal or straight gas. We are unable to change burner aiming position at this time

(adjustment turnbuckles).

- What are the flow rates of the fuels you are using? Approximately 5-6 TPH of Coal when on

straight coal. On straight gas approximately around 2400-3300 CFM. Fuel Usage depends on

process conditions.

- Please provide the composition of fuel gas/oil you are firing

– No Fuel Oil. Gas is natural gas.

Coal blend is a eastern coal.

- What are the flow rates of the atomizing/shaping/conveying air you are supplying?

- We have

been running with our atomizing air valve primarily at 75-100% open which would be

around 1100-1400 ACFM. At times we when we are on straight coal we may cut back on the

atomizing air valve to 20-30% open this would be approximately 600-1000 ACFM.

On Shaping Air we have been running mainly with 60-80% open on the valve when firing on coal

this would be approximately 1900 -2450 ACFM with swirl air valve open 2/3 and straight air

valve open 1/3. At times we have cut back the shaping air when firing on coal to 30% which is

around 600 ACFM. When firing on gas we open the shaping air valve at 95%-100%.

- What is the flow rate of the combustion air you are supplying to the burner? When firing on

coal our coal mill exhauster outlet flow rate has been 11,000 -12,000 ACFM. When firing on gas the

atomizing air and shaping air are at maximum flow rates.

- What are the NOx and CO emissions? What are the targets? Unable to provide this

information at this time.

- What is the temperature in the chamber?

– Unclear of question. UTAC is a grate- kiln

system. The Burners are located on discharge end of Kiln. Temperatures in the kiln are

approximately 2300-2400 F.

- Please provide a plant P&ID showing upstream and downstream processes and conditions

–

Attached is the flowsheet of the Induration Furnace

- Please provide composition of the material being treated in the kiln

– Iron Ore Pellets

–Magnetite.

Other information: Natural Gas Orifice (linear actuator) on Line 1 Burner is usually open 60-80% open

except for start-up on straight gas when we open (linear actuator) orifice to 100% open.

Conamara Line 2 Burner Information:

Generally running a mix of coal and gas on Line 2 furnace. Coal burner is a separate burner. Generally

running around 1000 CFM of gas then 5-6 tons of coal.

Shaping Air Fan and Atomizing Air fan always running at maximum flow all the time (no matter what

fuel combination is being burned). Shaping Air flow around 2500 CFM. Atomizing Air around 1400 CFM.

On Line 2 Conamara Burner generally natural gas orifice (linear actuator) is always 100% open.

Temperatures in Kiln, material composition and Induration flow sheet apply to both Line 1 and Line 2

Furnace.

The information above will be useful in helping us determine where the excess NOx is coming from, and

what measures may be required to reduce it. Please let me know if you have any questions.

Thank you,



### Chris Onysko

Project Manager

COnysko@aecometric.com

____________________________________________________________________________________________________________

Aecometric Corporation / Conamara Limited

374 Ohio Road

Richmond Hill, Ontario

L4C 2Z9

Tel: (905) 883-9555 x.255

Fax: (905) 883-9578



### www.aecometric.com