into any comparative discussion as to the methods generally of mine flushing, for that is explained most comprehensibly in detail in the paper by James B. Davis, published in the Mine Inspector's Report of 1891; United States Government Report of 1913 by Charles Enzian;3 and also by Dever C. Ashmead, in the issue of Coal Age of September 4, 1921. The flushing system in use by the Kingston Coal Go. is practically the same as that of other companies. All slate and rock from the platform, picking tables, Emery and spiral pickers, and jigs, are run by chute or conveyor to a central pocket near the foot of the breaker and fed into a 36 by 42 inch hammer crusher operated at 800 revolutions per minute—screen bar opening of threeeighths inch. A 2-inch stream of water plays into the crusher to allay dust and prevent blocking. The pulverized material is then mixed with the fine washings from the screen and run through a terra-cotta-lined trough to the borehole. Enough water is added, making the mixture from five to eight parts water, as may be required, to carry the silt into the entire length and grade of the pipe line. Duplicate boreholes are provided to permit changing from one vein or district to another. These boreholes have a full 6-inch opening. A drive pipe is sunk through the surface to the hard rock of sufficient diameter for the insertion of 1%-inch-thick glazed terra-cotta ring pipe and cement between the iron casing and terra cotta about 2 inches thick. The necessary location of the borehole at times required drilling through openings in intermediate veins. In that case a box was built through the vein to guide the drill. After the completion of the borehole terra-cotta ring pipe is set in the openings, properly cemented into the roof and bottom, and concrete abutment built around the pipe. Where openings in such veins are accessible, we insert in the concrete a cast-iron flanged tee, fitted with a slide for emergency outlet. At the bottom of the borehole a cast-iron elbow of long radius is cemented into place. To this is attached a cast-iron fitting, designed for connection to cast-iron bellmouthed pipe. The bell and spigot joints are made with wood wedge 1 inch thick driven in close together. We have almost entirely discarded the use of oakum or hemp. We do not use lead joints on account of the time and expense consumed in repairs and cleaning of the lines. Bolted joints were found unsatisfactory on account of rusted threads. At times our lines have been blocked the entire distance from borehole to flushing point. The same also applies to the borehole, but the rule has been to persevere and though such reopening is laborious and costly, yet the results of our silting have justified the expense. It is a simple matter to knock out the wood wedge and take the line apart provided you have willing, expert men. Five joints are usually sufficient to take a bell-and-spigot line apart. The silt is then cleaned out with a hoe. Reopening blocked boreholes entails more labor and expense. Our method is to take half-inch galvanized pipe cut into lengths equal to the height of the vein and screw together. The first pipe is tipped with a steel nose. The foot elbow is removed and the tipped pipe forced up into the culm, section for section, until the end of the blockage is finally reached; then water under pressure erodes the culm. We have found cast-iron bell-and-spigot pipe preferable to steel or wrought iron. Cast-iron pipe possesses an advantage of wearing smooth, thereby reducing the resistance of the flow of water. The length of pipe is 12 feet per section. The life of the cast-iron pipe depends upon the 'Enzian. C, Hydraulic Mine Filling; Ita Use In the Pennsylvania Anthracite Fields, a quality of the water. We are fortunate in having nonacidulous water from the Orchard vein; its analysis is as follows: Analysis of mine water Grains per Silica 2. 50 li on and alum oxides 2. 62 Sodium chloride 1. 57 Calcium sulphate 26. 33 Sodium sulphate _- 6. 72 Magnesium sulphate 7. 40 Total solids 59. 35 The water shows a slight alkalinity that for practical purposes is neutral in reaction. At the beginning of our flushing operations we used indiscriminate mine water, and the life of the pipes was not more than three to six months, even though we changed our pipes one-fourth turn every couple months. It was finally decided to use only Orchard vein water. The capacity of the Orchard vein sumps was doubled. The water is allowed to accumulate in the large Orchard vein sump at the foot of the inside slope and pumped from there to the bottom of No. 1 shaft. From that point it is pumped to the outside reservoir and from there distributed to the different breakers and crushing plants. The use of the Orchard vein water has lengthened the life of the equipment used in wet preparation and mine flushing. The life of our silt lines is now about two years. The length of our main silt is 6,600 feet, 6 inches in diameter. The discharge point is 250 feet higher than- the bottom of the 500-foot borehole. We have experienced the bursting out of sections of perfectly good pipe from undue pockets of compressed air carried with the water down the borehole, said pockets being caused by the gradual blocking of the pipe beyond and the inrush of silt. This illustrates the strength of the wedged joint. The silt through the long lines does not discharge in a steady stream but passes out in gushes. The batteries built at the bottom of the chambers are constructed in different ways, the method depending upon the conditions encountered. The general practice, however, is to set 12-inch timbers vertical, about 2-foot centers. The timbers are set in hitches cut in the bottom rock and are wedged at the roof. Halfway up a horizontal timber is set in place, supported by posts and braced to the hitches cut in the bottom rock and roof. The face of the battery is covered with 2-inch hardwood plank. The cracks are filled with hay, which permits drainage of water but prevents the escape of the silt. Silt is porous and must be treated as to pressure as a liquid. Water should not be used for more than one circuit. In taking out local pillars or stumps the opening should be flushed at once to restore the solidity of that section. One of the essentials in silting is to give attention to proper drainage and not silt over a wide and inaccessible area; that might result in confined bodies of water. We use to advantage 8-inch pipe for our main trunk line and uphill, capacity 1,000 gallons per minute. A 6-inch pipe under a pressure and down grade will work satisfactorily. In the past 15 years we have put back into the mines 250,000 cubic yards of ashes. Ashes alone are harder to flush than when mixed with fine coal and rock. We have experienced difficulty in trying to silt ashes to a higher level. The wear is also harder on the pipe lines, due to the sulphuric acid and the friction on the metal. Wherever possible the ashes should be mixed with breaker silt. Care should be used in the drainage opening and the overflow to a well for the pump suction. Whenever there is a depression in the silt line the pipe should be cleaned out frequently to remove the heavy "sulphur" particles that collect in the depressions. It is our custom to flush the lines out with clean water before the breaker starts, also at noon and the close of the day, also at night to plug the top of boreholes that there may be no accumulation of drippings from the breaker, etc. Precautionary measures with regard to the collection of gas should be used in all silted districts and in opening pipe lines and boreholesuse safety and electric lamps. At Kingston silting operations are all on gravity flow, from breaker, while at Gaylord the location of the breaker required a pumping plant. For the past 14 years said pumping plant has been in continuous operation, lifting a mixture containing about 10 per cent of solids to an elevation of 228 feet through 2.800 feet of 8-inch cast-iron pipe. This material is then run down boreholes and thence distributed by pipe lines where required. At Gaylord we use the water from the Susquehanna River. The pumping of this material requires special valves and seats for the pumps, a gravity intake to the pump instead of suction lift, and the pipe line provided with tees at regular intervals in case of blocked lines. We have found that 8-inch diameter pipe gives about the best results for our 10 by 36 inch pump. In the winter the use of exhaust steam in the mixture prevents the freezing of the silt in the pipe lines. A point of interest in connection with our silting was the extinguishing of the Are in the Dodson mine of the Plymouth Coal Co. The fire was in the caved section of the Red Ash vein, which is about 20 feet thick, but by perseverance and the concentration of our silt operations we effectually surrounded and isolated the section and extinguished the fire, also stiffening the pillar support. We have tried sand and loam, but find such impracticable in uphill discharge. Another point of interest, where a squeeze occurred we spread out silt en masse over the bottom of the chamber with a taper or batter half way up the pillar, and it was surprising how quick were the results that we obtained in stopping the squeeze. In the Orchard vein district the first mining was 24-foot chamber with 36-foot pillar. The gangways, headings, and chambers were flushed tight. A new gangway was driven in the coal along the high rib of the old gangway (see map, fig. 43). Advancing along the farther side of the pillar betwen the old chambers a cut 18 feet wide was made the entire length of the pillar. When the end of the pillar was reached the remaining length of 18 feet was taken out in the retreat. In the retreat 7-foot cogs were set every 30 feet in the center of the opening. The bottom rock was taken up advancing to permit transportation. The rock removed was packed along the left side, making a substantial 6-foot wall in front of the silt pillar. This, in the final extraction of the pillars, left an opening of 30 feet. The cogs in the hand wall retarded the settling sufficiently to prevent the breaking of the roof until the artificial pillars took the load. The percentage of recovery is practically 100 per cent, and the surface shows no sign of disturbance. Our experience is that the composite mass of ground-up slate, rock, and fine coal has made a most effectual artificial pillar as applied to the workings of the Kingston Coal Co. We have not gone into detail as to the relative cost of our flushing system or the value of the tonnage of pillar coal thus far reclaimed or available in the future, nor have we gone into a comparison as to the cost relative to the surface dump, nor as to the question of the commercial value of the fine coal if FIGURE 43.—Map of part of Red Ash bed at Kingston No. 2 colliery of Kingston Coal Co., showing method of recovering pillars Whenever there is a depression in the silt line the pipe should be cleaned out frequently to remove the heavy "sulphur" particles that collect in the depressions. It is our custom to flush the lines out with clean water before the breaker starts, also at noon and the close of the day, also at night to plug the top of boreholes that there may be no accumulation of drippings from the breaker, etc. Precautionary measures with regard to the collection of gas should be used in all silted districts and in opening pipe lines and boreholes— use safety and electric lamps. At Kingston silting operations are all on gravity flow, from breaker, while at Gaylord the location of the breaker required a pumping plant. For the past 14 years said pumping plant has been in continuous operation, lifting a mixture containing about 10 per cent of solids to an elevation of 228 feet through 2,800 feet of 8-inch cast-iron pipe. This material is then run down boreholes and thence distributed by pipe lines where required. At Gaylord we use the water from the Susquehanna River. The pumping of this material requires special valves and seats for the pumps, a gravity intake to the pump instead of suction lift, and the pipe line provided with tees at regular intervals in case of blocked lines. We have found that 8-inch diameter pipe gives about the best results for our 10 by 36 inch pump. In the winter the use of exhaust steam in the mixture prevents the freezing of the silt in the pipe lines. A point of interest in connection with our silting was the extinguishing of the fire in the Dodson mine of the Plymouth Coal Co. The fire was in the caved section of the Red Ash vein, which is about 20 feet thick, but by perseverance and the concentration of our silt operations we effectually surrounded and isolated the section and extinguished the fire, also stiffening the pillar support. We have tried sand and loam, but find such impracticable in uphill discharge. Another point of interest, where a squeeze occurred we spread out silt en masse over the bottom of the chamber with a taper or batter half way up the pillar, and it was surprising how quick were the results that we obtained in stopping the squeeze. In the Orchard vein district the first mining was 24-foot chamber with 36-foot pillar. The gangways, headings, and chambers were flushed tight. A new gangway was driven in the coal along the high rib of the old gangway (see map, fig. 43). Advancing along the farther side of the pillar betwen the old chambers a cut 18 feet wide was made the entire length of the pillar. When the end of the pillar was reached the remaining length of 18 feet was taken out in the retreat. In the retreat 7-foot cogs were set every 30 feet in the center of the opening. The bottom rock was taken up advancing to permit transportation. The rock removed was packed along the left side, making a substantial 6-foot wall in front of the silt pillar. This, in the final extraction of the pillars, left an opening of 30 feet. The cogs in the hand wall retarded the settling sufficiently to prevent the breaking of the roof until the artificial pillars took the load. The percentage of recovery is practically 100 per cent, and the surface shows no sign of disturbance. Our experience is that the composite mass of ground-up slate, rock, and fine coal has made a most effectual artificial pillar as applied to the workings of the Kingston Coal Co. We have not gone into detail as to the relative cost of our flushing system or the value of the tonnage of pillar coal thus far reclaimed or available in the future, nor have we gone into a comparison as to the cost relative to the surface dump, nor as to the question of the commercial value of the fine coal if |