### Cliffs Natural Resources Barr Engineering Co.

Hibbing Taconite Company October 22, 2010 Hibbing, Minnesota

Pellet Indurating Furnace Line 2 Testing performed on 6/3/010 Test Condition: Furnace Line 2 Low Temperature Firing Condition

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 **SV028 Stack A** 1319-13401400-14211440-15011517-15381553-16141629-16501706-17271741-18021815-18361850-1911 Ref. Method lb/hr 55.0 53.1 55.2 52.8 53.1 52.0 53.4 52.8 53.6 52.2 PEM lb/hr 96.7 82.9 83.4 87.6 88.6 88.2 87.2 80.7 81.9 82.6 Difference 41.8 29.7 28.2 34.8 35.4 36.2 33.7 28.0 28.2 30.4

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 **SV027 Stack B** 1319-13401400-14211440-15011517-15381553-16141629-16501706-17271741-18021815-18361850-1911 Ref. Method lb/hr 91.3 84.8 88.9 89.4 88.9 87.2 87.0 88.9 90.6 87.4 PEM lb/hr 121.3 115.9 116.0 116.8 116.2 116.3 115.6 115.5 114.4 115.7 Difference 30.0 31.1 27.0 27.4 27.3 29.2 28.7 26.6 23.9 28.3

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 **SV026 Stack C** 1319-13401400-14211440-15011517-15381553-16141629-16501706-17271741-18021815-18361850-1911 Ref. Method lb/hr 125.2 122.7 125.4 125.0 124.8 124.4 126.0 126.9 128.6 125.4 PEM lb/hr 122.3 116.8 116.2 114.9 116.5 115.1 120.2 116.7 119.3 117.7 Difference -3.0 -5.9 -9.1 -10.1 -8.3 -9.4 -5.8 -10.3 -9.3 -7.7

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 **SV025 Stack D** 1319-13401400-14211440-15011517-15381553-16141629-16501706-17271741-18021815-18361850-1911 Ref. Method lb/hr 142.9 143.7 144.2 144.4 143.1 144.3 144.6 146.7 144.2 142.9 PEM lb/hr 130.3 120.8 120.3 123.2 123.4 122.7 123.5 123.3 123.6 125.7 Difference -12.7 -22.9 -23.9 -21.2 -19.6 -21.5 -21.2 -23.4 -20.7 -17.2 

### All Runs

### Cliffs Natural Resources Barr Engineering Co.

Hibbing Taconite Company October 22, 2010 Hibbing, Minnesota
Test Condition: Furnace Line 2 Mid Temperature Firing Condition Emissions Calculations 6/3/10 SV028- Stack A Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10

DSCFM 142,195 140,618 139,459138,353 138,509 138,171 136,514 137,361 137,217138,696 NOIx bias corrected ppm 62 62 62 61 63 62 63 62 62 60 Emission Calculations

NOx lb/hr 63.5 62.7 61.9 60.5 62.4 61.6 61.2 61.1 61.1 59.8

SV027 - Stack B Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10

DSCFM 175,688 174,442 176,489176,204 176,314 172,095176,699 173,831 173,969175,919 NOIx bias corrected ppm 82 81 82 81 84 83 82 82 83 81 Emission Calculations

NOx lb/hr 103.2 101.6 104.1 102.3 105.9 101.9 104.3 102.7 103.2 101.8

SV026 - Stack C Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10

DSCFM 167,086 162,537 161,065162,548 160,578 158,526 159,209 158,929 158,924158,805 NOIx bias corrected ppm 123 122 124 122 125 123 123 124 125 122 Emission Calculations

NOx lb/hr 146.7 142.6 142.8 142.4 144.3 139.4 140.5 141.2 142.6 138.9

SV025 - Stack D Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10

DSCFM 146,690 148,711 149,968149,514 150,410 149,036 145,810 146,701 148,019146,679 NOIx bias corrected ppm 150 151 153 151 154 152 151 152 155 151 Emission Calculations

NOx lb/hr 158.2 161.0 164.1 162.1 166.4 161.9 157.9 159.8 164.8 158.6

### Cliffs Natural Resources Barr Engineering Co.

Hibbing Taconite Company October 22, 2010 Hibbing, Minnesota

Emissions Calculations 06/02/10 SV028 Stack A Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10

DSCFM 139,175 140,140 140,388141,452 139,566 138,712 139,399 137,529 140,546139,400 NOIx bias corrected ppm 65 65 66 66 64 66 64 66 64 64 Emission Calculations

NOx lb/hr 64.9 64.9 66.2 66.4 64.1 65.2 64.2 64.9 64.5 64.1

SV027 Stack B Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10

DSCFM 169,282 174,365171,680 175,575 171,971 173,488 172,685172,288 178,830174,729 NOIx bias corrected ppm 88 87 88 88 85 88 86 88 87 88 Emission Calculations

NOx lb/hr 106.2 108.5 108.4 110.3 105.2 109.3 106.9 108.2 111.6 110.0

SV026 Stack C Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10

DSCFM 165,160 163,442 164,097 162,900 162,080 161,471 163,321 165,072 162,470163,584 NOIx bias corrected ppm 135 133 137 136 134 136 136 137 136 137 Emission Calculations

NOx lb/hr 159.8 155.9 161.1 158.3 155.4 157.8 158.6 162.2 158.3 160.2

SV025 Stack D Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10

DSCFM 152,808 152,569 152,688153,648 151,408 151,061 148,533 151,250 150,007149,554 NOIx bias corrected ppm 172 168 174 171 171 173 173 172 171 172 Emission Calculations

NOx lb/hr 188.0 184.1 190.4 188.2 185.4 187.0 183.9 186.9 183.9 184.0 

### Test Condition: Furnace Line 2 High Temperature Firing Condition