July 19, 1918. THE COLLIERY GUARDIAN 125 NOTES ON SAND-FILLING IN MINES.* By C. H. Greathead. The essential features of the sand-filling plant on the Simmer and Jack Proprietary Mines Limited were fully described by Dr. W. A. Caldecott and Mr. 0. P. Powell in a paper read in 1913, and since there have been no radical changes in the principles of sand-filling as then practised. The following notes relate to minor alterations that have been introduced in practice, and the development of various methods that have been put into operation in the reclaiming of pillars—foot and hanging walls in portions of the mine that have been virtually abandoned for a considerable number of years; also to the effect that sand-filling has had on portions of the mine where large areas have been sand-filled owing to there having been a considerable movement in the hanging. A further improvement* in draining areas which have only one or two boxholes at the bottom to drain through (the two sides being contained between dykes, or solid blocks of ground), or areas which for some reason or other contain an excessive amount of water in the sand and which must be drained rapidly, has Fig. 1. been effected by using a launder with a false bottom with ash clinker on top of it. This launder replaces the old square box launder with holes in the sides, which had to be plugged as the sand and water rose and covered the holes. Occasionally the native watch- ing the work forgot to put the plug in, and a con- siderable amount of sand was washed into the drives. The clinker launder obviates this danger, and be- sides requiring no supervision, also continues to drain below the surface of the sand for a considerable time. Launders have been standardised, and only three patterns are now used (fig. 1). In the case of drives on reef which have crushed badly in parts, and where it is impossible to put the barrier on the back of the drive pillars, owing to the stope above being caved in, ordinary square set- ting is put in and lagged over with 3 in. by 9 in. deals or in. by 9 in. hardwood planks; on the top of the planks a 6 in. layer of ash clinker, coarse at the bottom and finer on top, is placed, and the stope filled as usual. The ends of the square setting are masoned up sufficiently well to be sand-proof, which is rather expensive, but has answered remarkably well in places which otherwise would have been impossible to sand-fill. One level which was sand-filled in this manner nearly three years ago is at present in perfect order, and has taken no further weight. It is not, however, always necessary to put in complete sets as often; only a cap piece or a leg and cap piece are necessary. In stope barriers jute matting has been tried instead of cocoanut matting, but it has been discarded again, as it rots too rapidly, and when wet swells and tends to hold water instead of filtering rapidly. V-shaped launders have also been tried, but have not been found very satisfactory, as they are liable to overflow if the sand pulp is thick. In some wide stopes where mining operations are still being carried on, the stope has been partly filled without any side barrier, by shovel- ling up the sand in the form of a wall, much on the same principle as a slime dam wall. The sand wall is battered at an angle of about 35 degs., and the water is carried off by means of a launder and pipes, which are altered to suit daily requirements (see fig. 2). An ash drain launder might be more effective,but by carry- ing the drain pipes outside the sand-filled area they are easily recovered, whereas the ash drain launder would either have to be abandoned or dug out. Towards the middle of 1915 a considerable move- ment of the hanging wall commenced on the eastern boundary on the 14th level, and this movement steadily spread in a south and south-westerly direction down to the 28th level and seriously threatened the loss of about one-third of the No. 3 shaft section of the mine. Several reclamation sections had to be abandoned owing to the impossibility of making these places safe, owing both to the expense and height of the workings, which in places were 15 ft. in width. Several stope faces were also abandoned, as the hanging broke the timber props and caved in over the pigsties and packs, these “ falls ” commenced in the older portions of the stopes, where the supports were insufficient, but also extended to the face, where the pigsties were put in systematically, and which were very well timbered, but this did not stop the movement, which by this time had become very serious. Several accidents, two of which were fatal, occurred, due to pressure bursts, whilst the 16th to 27th levels caved in completely in the area of the movement, necessitating re-opening and re-timbering. Sand-filling was commenced, and a scheme laid out in order to save those stopes that were still being worked on the 27th and 28th levels. Barriers of light timber and matting were run up from the drive pillars parallel to the stope faces and about 15 ft. distant, the boxholes were closed off with lagging, matting and * Journal of the Chemical, Metallurgical and Mining Society of South Africa. cinders, and the space between was sand-filled. This in no way interfered with the current mining opera- tions, and it was noticed that when the stope had become about half full of sand, pressure bursts on the face became less frequent, and by the time the sand had filled the stope these had almost ceased. Along the drives, especially on 26th level, where several accidents had occurred owing to the drive pillars bursting, the movement ceased entirely after the stopes above and below had been filled for several months, and up to the present, a period of over two years, there have been no signs of any further move- ment Sand has now been filled up to the 25th level, and a considerable reclamation of foot and hang- ing and drive pillars obtained along the 25th and 26th levels, as well as a considerable amount of sweep- ings in the old stopes, portions of which have now been re-entered. The tonnage obtained from this work amounted to 86,976 tons of payable ore. Two faces which were last worked in 1913 and 1914 have been recovered and are now being worked. Sand-filling has been discontinued in this area for some months, to enable the recovery of sweepings and reclamation rock. When this has been done, sand-filling will be re- Fig. 2. f Ay MtDOi /”<■•> Ta„ cry ABOU r /4-OC)Ci Wr _______J&SXZX started for the further recovery of reclamation rock higher up in the mine. Valuable faces were recovered after entirely filling the stopes and then flushing out a raise through the sand along the faces. It is essential, wThen raising through sand-filling areas, to keep next the hanging wall of the stope. Figs. 3, 4, 5 and 6 illustrate various methods of reclamation work in conjunction with sand-filling. The area of claims filled with sand at December 31, 1917, is equivalent to 77’7 claims, and represents 23’58 per Fig. 3. 0 a 4 1 V) * < on < Fig. 4. a X Is3 I X0 M , Holz to s Afzef / VCrlT/^AT^Orf cent, of the area stoped out. The exact number of tons of sand lowered is not available, as no early records were kept, but the known tonnage that was lowered up to December 31, 1917, is 1,722,585 tons. The total cost of disposal of sand on surface and sand-filling underground for the year ending 1917 amounted to 6’974 pence per ton of sand filled, and the cost of disposal of sand to dump for the years 1908-1909 (before sand-filling was started) amounted to 5-904 per ton of sand to dump, making a difference of 1-070 pence in favour of disposal of sand to dump. This is more than counterbalanced by the additional advantages of having the old worked-out areas perma- nently supported, the saving in cost of labour and material in re-timbering and supporting these areas, to say nothing of the additional safety, better ventila- tion, and additional ore obtained. Coal on the Rhone.—According to the Information, determined efforts are being made to increase the pro- duction of coal in the region of Lyons. Drillers are par- ticularly active on the left bank of the Rhone. The Blanzy concern is reported to have struck the coal forma- tion, and consequently there has been a renewal of activity in the district. The Blanzy boring at Miens Sud reached the coal at a depth of 302 metres and pierced numerous seams down to 557 metres, including one 3 metres thick. THE AMERICAN COAL TRADE. A feeling of optimism is engendered by the record production of bituminous coal during the week ended June 8 (says Coal Age, June 22), when the output of soft coal reached the unprecedented total of 12,465,000 short tons. This exceeds by 1,691,000 short tons the produc- tion of the preceding week. The average daily output was well above 2,000,000 short tons, which amount of coal must be shipped every working day for the rest of the coal year if estimated demands are to be met. Though the shortage of cars continues to act as a bar to the greater production of bituminous coal, particularly in West Virginia, this condition is being alleviated rapidly. There is promise that ere long the most important producing sections will be receiving close to 100 per cent, car allotment. Labour shortage bids fair to become the chief deter- ring reason to maximum output. Mr. James B. Neale, who heads the newly formed Production Bureau of the Federal Fuel Administration, is planning a nation-wide campaign to speed up coal production. The workers at the mines are to be addressed by well-known men. Market conditions are quite active. The sharp demand for domestic and steam grades continues, and the storing of domestic coal is going on at a good rate. However, receipts by dealers are not half the tonnage desired. Boston reports state that the coastwise shipments have not yet recovered from U-boat activity, but a considerable gain was made. There has been no day recently when the volume of coal was not largely in excess of the tonnage waiting at the piers. Anthracite, deliveries are short in Philadelphia. From the production standpoint it can be said that the tonnage is almost up to the record of last year. The reason that it is not more is only because the men are not in the region, and while the reduction of labour from month to month is not heavy, yet in the aggregate it is bound to make itself felt. Unlike the bituminous region, however, there is hardly any trouble in the car supply. In Baltimore the coal yards have been placarded with signs which tell all workers, of whatever degree, that the law of Maryland requires every man between the ages of 18 and 50 inclusive to be continuously employed. Notice is given that three or four days does not con- stitute a week’s work, and prosecution followed by fines and imprisonment, or both, will be inflicted on work slackers. Production of coal in the Connellsville region for shipment to by-product plants continues to increase somewhat, but on the whole there is inadequate labour performance. Representatives of the Fuel Administra- tion are investigating matters and hope to induce the men to work more regularly., Fig. 5. 0_ —r 9 3/5 «/f-° ^■4 SAwr'atO Fig. 6. The blast furnaces in operation have practically a full supply of coke. Many foundries have been in the market for contracts, but operators prefer to sell from time to time rather than make contracts. The market remains quotable at the set limits : Furnace, 6 dols.; foundry, 72-hour selected, 7 dols.; crushed, over 1-in., 7 dols. 30 cents per net ton at ovens. Imports of Pit Props.—The table below shows the quan- tity and value of pit props or pit wood imported in June :— 1917. 1918. 1917. 1918. Loads...... 97,633... 66,805.. 572,216... 427,729 Value...... <£103,687... <£434,197... <£2,103,660... £1,919,231 The Iron and Steel Trades Confederation.—The half- yearly meeting of the No. 2 Divisional Committee of the Iron and Steel Trades Confederation was held at Darlington on Saturday. The meeting passed a resolution protesting against the attempts of the Government to enforce a lower rate of wages upon women who take employment in the iron and steel trades, and calling upon the executive to oppose any extension of female labour in the trades unless the principle of equal pay for equal work is fully accepted.