## Cliffs Natural Resources Barr Engineering Co.

Hibbing Taconite Company October 22, 2010 Hibbing, Minnesota

Emissions Calculations

SV024 Stack A Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9

DSCFM 142,166 144,632 144,038 144,186 142,217 142,441 141,079 142,340 142,943 NOIx bias corrected ppm 87 88 87 87 89 87 91 88 87 Emission Calculations

NOx lb/hr 89.1 91.4 89.3 90.1 90.2 89.1 91.7 89.7 89.3

SV023 Stack B Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9

DSCFM 146,343 149,216 150,026 150,229 149,157 147,881 147,895 146,794 148,130 NOIx bias corrected ppm 78 79 77 79 79 79 81 79 79 Emission Calculations

NOx lb/hr 82.1 84.6 83.1 84.8 84.4 83.3 86.2 83.0 83.3

SV022 Stack C Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9

DSCFM 159,200 158,500 159,000 158,700 157,000 157,800 157,400 156,200 157,800 NOIx bias corrected ppm 55 56 53 55 54 55 56 55 54 Emission Calculations

NOx lb/hr 62.3 63.4 60.3 62.1 60.4 61.8 63.6 61.8 61.3

SV021 Stack D Airflow Rates Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9

DSCFM 162,924 163,076 163,231 161,977 162,975 160,562 160,251 161,932 162,071 NOIx bias corrected ppm 47 48 45 47 46 47 48 47 47 Emission Calculations

NOx lb/hr 54.8 56.5 53.2 55.0 53.6 54.3 55.3 54.7 54.4 Line 1 During Low Fire Conditions

### Cliffs Natural Resources Barr Engineering Co.

Hibbing Taconite Company October 22, 2010 Hibbing, Minnesota
Results of the Nitrogen Oxides Relative Accuracy Test Audit
Testing performed on May 3, 2010 Test Condition: Furnace Line 1 Mid Temperature Firing Condition

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 Run 11 **SV024 Stack A** 1050-1111 1128-11491205-12261240-1301 1316-13371403-14241436-14571513-15341549-16101628-16491705-1726 Ref. Method lb/hr 107.8 105.0 106.1 102.5 113.6 111.4 112.9 118.2 118.3 114.2 118.9 PEM lb/hr 144.6 146.6 148.8 144.3 146.2 143.7 146.5 142.4 142.6 146.4 144.2 Difference 36.8 41.5 42.8 41.8 32.6 32.3 33.6 24.2 24.2 32.3 25.3

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 Run 11 **SV023 Stack B** 1050-1111 1128-11491205-12261240-1301 1316-13371403-14241436-14571513-15341549-16101628-16491705-1726 Ref. Method lb/hr 100.0 98.3 100.0 98.4 107.9 104.3 105.9 110.5 111.4 107.9 110.4 PEM lb/hr 138.3 136.5 139.5 139.5 140.2 133.2 131.9 134.7 135.5 138.1 139.4 Difference 38.3 38.2 39.5 41.1 32.3 28.9 26.0 24.2 24.1 30.1 29.0

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 Run 11 **SV022 Stack C** 1050-1111 1128-11491205-12261240-1301 1316-13371403-14241436-14571513-15341549-16101628-16491705-1726 Ref. Method lb/hr 73.6 72.4 71.7 72.6 77.8 75.7 77.2 81.0 80.0 77.8 81.3 PEM lb/hr 106.9 110.6 110.8 111.9 108.7 109.1 108.5 109.5 107.7 112.6 110.3 Difference 33.3 38.2 39.1 39.3 30.9 33.4 31.3 28.4 27.8 34.8 29.0

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 Run 11 **SV021 Stack D** 1050-1111 1128-11491205-12261240-1301 1316-13371403-14241436-14571513-15341549-16101628-16491705-1726 Ref. Method lb/hr 66.1 64.4 63.4 63.7 67.0 67.4 68.4 72.2 70.0 68.4 70.7 PEM lb/hr 106.7 105.2 107.2 106.8 107.3 103.1 101.6 107.0 107.9 108.3 108.9 Difference 40.6 40.8 43.8 43.1 40.3 35.7 33.2 34.8 37.9 39.9 38.3

### Cliffs Natural Resources Barr Engineering Co.

Hibbing Taconite Company October 22, 2010 Hibbing, Minnesota

Pellet Indurating Furnace Line 1 Testing performed on May 4, 2010 Test Condition: Furnace Line 1 High Temperature Firing Condition

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 **SV024- Stack A** 730-0751 810-0831 843-09041008-10291047-11081123-11441157-12181230-12511302-13231337-1358 Ref. Method %, dry 125.4 127.9 126.7 121.8 124.5 122.8 122.3 123.8 127.6 125.9 CEM %, dry 158.3 155.0 153.4 153.1 153.8 151.8 150.5 150.4 149.5 149.8 Difference 32.9 27.1 26.7 31.4 29.3 29.0 28.1 26.6 21.9 23.9

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 **SV023 Stack B** 730-0751 810-0831 843-09041008-10291047-11081123-11441157-12181230-12511302-13231337-1358 Ref. Method %, dry 115.3 117.5 117.0 113.2 116.2 116.4 115.9 114.5 120.8 118.6 CEM %, dry 152.4 149.8 149.1 144.7 151.7 146.0 144.6 147.7 140.4 141.5 Difference 37.2 32.2 32.1 31.5 35.6 29.6 28.6 33.2 19.6 22.9

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 **SV022 Stack C** 730-0751 810-0831 843-09041008-10291047-11081123-11441157-12181230-12511302-13231337-1358 Ref. Method lb/hr 83.1 89.6 85.7 85.2 85.5 84.6 85.7 83.1 88.1 84.1 CEM lb/hr 114.3 116.0 111.4 113.1 116.4 113.4 117.0 113.5 111.9 110.0 Difference 31.2 26.4 25.6 27.9 30.9 28.9 31.3 30.5 23.8 25.9

**NOx** Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9 Run 10 **SV021 Stack D** 730-0751 810-0831 843-09041008-10291047-11081123-11441157-12181230-12511302-13231337-1358 Ref. Method lb/hr 74.2 79.8 75.7 75.6 77.5 76.0 77.7 74.6 79.6 75.7 CEM lb/hr 109.6 108.0 107.4 105.5 110.6 107.3 106.6 108.3 108.3 109.4 Difference 35.4 28.2 31.7 29.9 33.1 31.3 28.9 33.7 28.7 33.8 All Data