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[blocks in formation]

Point of
ignition

>Posts on 8-foot centers with boards on bottom

47-135 0.71 - 2

Roof bolted

[blocks in formation]

2 face 4 a.c. right 19,140 c.f.m.

Sketch of Scene of Gas (Frictional) Ignition

Gateway Mine

Gateway Coal Company
Clarksville, Greene County, Pennsylvania

May 26, 1969

Scale 1" = 10'

->Intake air Return air

UNITED STATES
DEPARTMENT OF THE INTERIOR

BUREAU OF MINES

Coal Mine Safety District A

REPORT OF COAL MINE GAS (FRICTIONAL) IGNITION

GATEWAY MINE

GATEWAY COAL COMPANY CLARKSVILLE, GREENE COUNTY, PENNSYLVANIA

June 9, 1969

by

Henry Zavora Federal Coal Mine Inspector (Roof Control)

Originating Office - Bureau of Mines 4800 Forbes Avenue, Pittsburgh, Pa. 15213 W. Dan Walker, Jr., District Manager

Coal Mine Safety District A

REPORT OF COAL MINE GAS (FRICTIONAL) IGNITION

GATEWAY MINE

GATEWAY COAL COMPANY
CLARKSVILLE, GRHINE COUNTY, PENNSYLVANIA

June 9, 1969

by

Henry Zavora
Federal Coal Mine Inspector (Roof Control)

INTRODUCTION

This report is based on an investigation made in accordance with provisions of the Federal Coal Mine Safety Act (66 Stat. 692; 30 U.S.C. Secs, 451-483) as amended.

Gas was ignited about 7 a.m., Monday, June 9, 1969, at the face of No. 1 entry just inby 7-1/2 room 7 butt 3 face in the Gateway mine. The incident occurred when the bits of the cutting chains of a Joy 1-CM continuous miner struck roof rock and ignited methane feeders during mining of the first sump of a reactivated place. The extent of the flame was limited to the mined sump, and the flame was extinguished immediately by the direct application of water from a hose. There were no injuries or property damage.

John A. Noon, Federal Coal Mine Inspection Supervisor, Waynesburg,
Pennsylvania, was notified by a telephone call from J. M. Blair,
Safety Director, at 8 a.m. on the day of the occurrence, and the
investigation was started promptly thereafter.

GENERAL INFORMATION

Mine openings consist of 6 shafts and 2 slopes. Operations are in the Pittsburgh coalbed, which averages 68 inches in thickness in this area. Employment was provided for 585 persons, of whom 551 worked underground and 34 on the surface. The average daily production was 8,500 tons of coal.

A block system of mining was practiced. Four entries were being developed in 7 butt 3 face toward virgin territory. Entries and crosscuts were on 85-foot centers. The No. 1 entry was about 17 feet wide and had been advanced about 105 feet from the last open crosscut at 6-1/2 room about a week prior to the occurrence. It was ventilated by means of line brattice while it was idle.

The immediate roof varied from coal to rock in No. l entry, 7 butt 3 face and clay veins had been encountered. Roof bolting in accordance with a Bureau-approved plan was being done by means of equipment mounted on the continuous miner. Bearing plates were 6-inch by 6-inch by 1/4-inch bell-embossed steel. The last bolts installed in the place were about 16 feet and 12-1/2 feet from the face on the left and right sides, respectively.

The mine is classed gassy in accordance with the laws of the State. Ventilation was induced by five fans operated exhausting and properly installed on the surface. At the time of the last Federal inspection, about 1,307,180 cubic feet of air a minute was being circulated throughout the mine and about 5,154,000 cubic feet of methane was being liberated from the mine in 24 hours. A split system of ventilation was used in the mine. Check curtains, line brattices, and permissible-type auxiliary fans were used to direct the air to face regions.

At the time of the investigation about 32,470 cubic feet of air a minute was used to ventilate the 7 butt 3 face section. The air current was directed up No. 2 entry and was divided. About 11,900 cubic feet of air a minute was directed into the right split and 20,570 cubic feet was measured in the return of the left split of air. The No. 1 entry was ventilated by the left split of air. Tests made with electric methane detectors revealed me thane feeders at the face of No. I entry. Laboratory analyses of air samples collected during this investigation are shown in table 1.

The mine surfaces varied from wet to dry. Rock dust had been applied in the face area in No. 1 entry. Water was used to allay dust created during mining. The continuous miner in 7 butt was equipped with 10 water sprays.

Direct-current electric power, at 250 volts, was used to operate the face equipment. Electric face equipment in use in 7 butt 3 face consisted of a Joy 1-CM continuous miner, a Joy 11BU loading machine, and two Joy l0SC shuttle cars. The equipment was permissible type and maintained in permissible condition. Trailing cables were flame resistant and provided with overload protection. The frame-ground conductor for the continuous miner was intact.

Permissible electric cap lamps were used for portable illumination underground. Smoking was not permitted in the mine.

Information for this report was obtained by an investigation at the scene of the occurrence and from statements made by Floyd Turcheck, Assistant Mine Foreman, and members of the crew who were present when the incident occurred: Willard Gill, continuous-miner operator; and Michael Benamatti and Charles Tedrow, roof bolters.

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The last Federal inspection of the mine was completed May 16, 1969.

DESCRIPTION OF OCCURRENCE

The crew of 7 butt 3 face section entered the mine at 12:01 a.m.,
Monday, June 9, and arrived on the section about 20 minutes later.
Mining operations were started in the crosscut in No. 2 entry at
7-1/2 room to connect it with No. 1 entry.

When the crosscut was driven through to intersect No. 1 entry, the former last open crosscut was closed off and the air current was directed through the crosscut just completed. The production of coal was delayed while roof bolts were installed to support the roof area of the last portion mined (about 16 feet) in the crosscut.

The assistant mine foreman examined the face regions of 7 butt section, including No. 1 entry, about 6:40 a.m. He detected no accumulation of methane and found no other danger. He continued his preshift examination for the oncoming shift by traveling the belt conveyor entry.

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