1. Development of Moisture Tolerant Rock Dust for Improved Mine Safety August 26, 2015 Dave Anstine - Senior Technical Leader, Building and Chemicals

2. Development Background Tragic explosion at the Upper Big Branch Mine in West Virginia in 2010 Extensive investigations were launched by the Mine Safety and Health Administration (MSHA) and found:  Mine was poorly dusted  78.92% were out of compliance with the federal standard The significance of the analysis and the role that Rock Dust played in the Upper Big Branch Mine explosion prompted MSHA to ask NIOSH to evaluate current Rock Dusts in North America and their compliance to specifications and its use in greater detail  47% of Rock Dust Samples did not meet the particle size requirement  All Rock Dust Samples tested, caked when wetted & dried and did not disperse with a light blast of air 30 CFR 75.2 Rock Dust Definition  Pulverized limestone, dolomite, gypsum, anhydrite, shale, adobe, or other inert material  Particle Size: ‒ 100% minus 20 Mesh ‒ Minimum 70% minus 200 Mesh  Particles of which when wetted & dried will not cohere to form a cake which will not be dispersed into particles by a light blast of air  Does not contain more than 5 percent combustible matter  Does not contain more than a total of 4 percent free and combined silica(SiO2) 04/12/2015Development of Moisture Tolerant Rockdust2

3. Current Rock Dust Samples Subjected to “Wet” Conditions 04/12/2015Development of Moisture Tolerant Rockdust3

4. Rock Dust Simple Caking Test 04/12/2015Development of Moisture Tolerant Rockdust4

5. NIOSH Dust Dispersion Chamber A laboratory dust dispersion chamber was developed by NIOSH to provide a reproducible air pulse across the surface of the sample to compare relative dispersibility of Rock Dust samples All test samples were subjected to the same 0.3-second pulse from a 40psi compressed air source to give a peak dynamic pressure of approximately 4.2 psi.. Sample trays were weighed before and after each air pulse to determine the amount of dust dispersed.. While this apparatus and test procedure cannot hope to duplicate the dust dispersal mechanism in advance of a propagating mine explosion, it does provide a repeatable dynamic pressure source and quantitative measure of the relative mass loss and dispersibility of dusts under controlled dispersion conditions. pressure. 04/12/2015Development of Moisture Tolerant Rockdust5

6. NIOSH Dust Dispersion Chamber 04/12/2015Development of Moisture Tolerant Rockdust6

7. NIOSH Dust Dispersion Trays with Rock Dust: After and Before Dispersion 04/12/2015Development of Moisture Tolerant Rockdust7

8. NIOSH Dust Dispersion Trays: Dry, Wet & Wet with Filter Paper 04/12/2015Development of Moisture Tolerant Rockdust8

9. NIOSH Dust Dispersion Chamber “Wet” Test Results: Current Rock Dust Samples 04/12/2015Development of Moisture Tolerant Rockdust9 Sample Identification Particle Size d(50) microns Dry Weight Loss (%) Wet Weight Loss (%) Imerys ImerWhite22.511.50 Competitive Sample #129.58.40 Competitive Sample #225.59.60 Competitive Sample #323.112.00 Competitive Sample #417.612.60 Competitive Sample #514.613.90 Competitive Sample #611.015.00 Competitive Sample #710.611.00

10. Humidity Chamber 04/12/2015Development of Moisture Tolerant Rockdust10

11. NIOSH Dust Dispersion Chamber “Wet” Test Results: Moisture Tolerant Samples 04/12/2015Development of Moisture Tolerant Rockdust11 Imerys Sample #Particle Size d(50) MicronsDry Weight Loss (%)Wet Weight Loss (%) 2A075K-925R35.28.12.4 2A125K-875R29.58.93.2 2A125S-875R28.19.33.3 2A075S-925R34.98.63.5 2A075S-925825.412.25.1 2A075S-925M21.611.95.3 2A125S-875M18.913.35.4 2A125K-875822.111.35.6 2A125S-875822.611.86.0 2A075S-9251016.013.46.1 2A125K-875M18.312.56.1 2A125S-8751014.613.46.1 2A075K-925M20.912.36.3 2A075K-925825.211.96.6

12. NIOSH Dust Dispersion Chamber “Wet & Humid” Test Results: Moisture Tolerant Samples 04/12/2015Development of Moisture Tolerant Rockdust12 Imerys Sample #Particle Size d(50) MicronsWeight Loss (%) 0 Days7 Days14 Days21 Days 2C100S-900M20.58.32.53.73.3 2B075K-925824.76.72.83.33.7 SU125K-875M19.17.12.93.33.1 2C075S-925M21.56.93.03.23.3 3100S-900M20.17.03.24.03.4 2C100K-900M20.37.13.25.14.3 2B125K-875M17.610.83.35.82.8 2B100K-900822.510.73.65.05.1 2C075K-925M21.06.93.92.13.0 3125K-875M19.47.74.03.03.2 2B100S-9001014.913.04.06.05.4 2B100S-900822.88.54.14.84.1 2B075S-925824.56.04.74.54.3 2C075S-9251013.811.64.84.24.1

13. Imerys Samples Tested in NIOSH 20L Explosibility Chamber 04/12/2015Development of Moisture Tolerant Rockdust13 Coal Concentration(g/cu.m)200 400 600 Rockdust Concentration(%)6570758065707580657075 Imerys Sample No. #2B075K-9258dntgono-nodnt gono-nodnt gono-no #2B100S-9008dntgo-gono-no dntgono-nodnt gono-no #2B125S-8758dntgono-nodnt gono-nodnt gono-no #2B125K-875Mdntgono-nodnt gono-nodntgono-nono #2B075K-925Mdntgono-nodnt gono-nodntgono-nono #2B100S-90010dntgono-nodntgono-gonodntgono-nono #2B125S-87510dntgono-nodntgono-nonodntgono-nono #3125K-875Mgono-gono-nodntgono-gono-nodntgono-gono-no #3100S-90010dntgono-nodntgono-gono-nodntgono-nono #3100S-900Mdntgono-nodntgono-gono-nodntgono-nono #SU125K-875Mdntgono-nodnt gono-nodnt gono-no ImerWhite dntgo-gono-nodnt gono-nodnt gono-no no-no = two tests conducted and both inerted the coal dust go = explosion no = no explosion, dnt = did not test

14. Modified & Current Rock Dusts: After “Wet” and Humid Conditions 04/12/2015Development of Moisture Tolerant Rockdust14

15. Imerys Rock Dust Samples Comparison to 30 CFR 75.2 04/12/2015Development of Moisture Tolerant Rockdust15 Imerys Sample #Particle Size d(50) um Sieve Retains:Combustible Material % % SiO2 Free & Combined 20% Mesh200% Mesh 30CFR-75.2 -0 (max)30 (max)5 (max)4 (max) 2A075S-925R34.9027.5<0.2<0.7 2A125K-875R29.5026.0<0.2<0.7 2B075S-925824.502.7<0.2<0.7 2B100K-900822.502.7<0.2<0.7 2B125K-875821.902.6<0.2<0.7 2C075S-925M21.500.3<0.2<0.7 2C100S-900M20.500.3<0.2<0.7 2C100K-900M20.300.3<0.2<0.7 3100S-900M20.100.3<0.2<0.7 3100S-9001020.10<0.1<0.2<0.7 SU125K-875M19.100.2<0.2<0.7 2B125K-875M17.600.3<0.2<0.7 2B125K-875M13.80<0.1<0.2<0.7 2B125S-8751012.80<0.1<0.2<0.7

16. Summary All samples have shown greatly improved dispersibility over the current Rock Dusts being used in North American coal mines when subjected to moisture and high humidity and then dried. The samples performed as well as the current Rock Dusts in their ability to inert explosions All samples meet the current requirements for 30CFR 75.2 Moisture Tolerant Rock Dust has been applied to a section of a Rib at the Bruceton Experimental Mine on the NIOSH Campus in Pittsburgh, PA  Compared to ImerWhite which was on a different section of a Rib  The Moisture Tolerant Rock Dust has been applied for over 6 months and is still dispersing with a light puff of air 04/12/2015Development of Moisture Tolerant Rockdust16

17. Questions?