December 8, 1916. THE COLLIERY GUARDIAN. 1111 ______________________________________________________________________________________________ TIGHTENING COKE-OVEN DOORS. Fig. 1.—Front elevation. B I Jo r I lc' lol d' The Von der Forst coke-oven door (figs. 1—4) is reported to have been successfully employed at a German cokery for some time. The essential feature of the fitment is that the door is provided with a sheet- iron frame a (figs. 1 and 2), which attaches the edges of the door to the wall of the oven, and thus leaves a large free space b open at the top, all round the door. In the case of straight doors, a large iron plate is used, this being secured to the back of the door, on the one hand, and extending to the iron uprights on the other. The cavity b is filled with packing material, such as coke breeze or granulated slag, which, as the oven heats up, is cemented together by the tarry vapours escaping through the crack of the door and condensing in the - material. When the charge has been pushed out of the oven and the door has been pushed home by means of the usual clamps and bar, the packing material is inserted, from above, into the side joints of the door, by means of a travelling receptacle, fitted 'with a delivery valve, mounted on door cable or on the charging machine. As an alternative a special car, running on the cable track, and containing enough packing for 10 doors, may be used. When coke breeze is employed, this material is preferably used fresh from the coke screen or brought, on an overhead runway, from the coke- breeze tower, by gravitation. The breeze should not be less than about ^-inch diameter. The unconsumed liberated each time a door is opened or lifted is returned to the coke screens, so that a portion of the packing ma- terial is used over again for tightening other doors. The time required for packing in the above manner is less than that needed for luting with clay. Existing oven doors can be adapted for this method of pack- ing, without difficulty. In the case of straight doors, iron plates of the requisite length and width are fixed on the back of the door. For dished doors, cast iron fillets c (figs. 3, 4) are bolted to the plates, which are provided, with riveted flanges d. The cost of the doors averages £8 10s., or about £4 more than that of ordinary doors; but, on the other hand, since a battery of 60 ovens can be managed by two men, the labour of three Inters is saved, equivalent to about one-eighth of the addi- tional cost of the doors in a year, to say nothing of the smaller cost of packing material. The cost of adapting existing doors is about £6 each. breeze Fig. 2.—Horizontal section. Fig. 3. Horizontal sections through adapted door (fig. 3 along A—B, fig. 4 along C—D, of fig. 1). The Von der Forst Coke-Oven Door. a Fig. 4. 71'777//, A ? Fig. 5.—The Beckers Self-tightening Door. A self-tightening door, introduced by Beckers and Co., Dusseldorf, is illustrated in fig. 5. The door 6, the edges of which are turned back, is provided with bolts g, on which slide the frame e and the tightening fillets d. When the door is inserted into its frame a, which is also recessed, the frame e and fillets d fit into the wedge-shaped open space between door and door frame, and the door is then tightened up by the screws i, which are mounted in swing nuts attached to block h on the door frame. As the charge in the oven swells, the pressure against the door compresses the fillets d still more tightly against the door frame. An interchange- able sill plate I at the bottom of the door ensures a tight joint at this point, which is exposed to wear. _________________________ COAL MINING IN INDIA IN 1915.* The report presented by Mr. H. H. Hayden, Director of the Geological Survey of India, states that the value of the coal output decreased from £3,907,380 in 1914 to £3,781,064 in 191b, a decline of 3 2 per cent.; at the same time the actual quantity produced increased con- siderably, having risen from 16,464,263 tons in the preceding year to 17,013,932 tons. This means that there was a considerable fall in the price of coal, the direct cause being the scarcity of steamers and the con- sequent restriction of exports from Calcutta to other Indian ports, the pit’s mouth price falling in the Bengal fields from Rs. 3-13-10 per ton in 1914 to Rs. 3-6-2 in 1915, and in Bihar and Orissa from Rs. 3-3-4 to Rs. 2-15-6. By far the largest proportion, viz., 16,673,237 tons, was produced in the Gondwana coal fields, and the remaining 430,695 tons in the tertiary coal fields. Exports from Bengal to Ceylon rose considerably, while those by sea to Indian ports fell from the normal figure of over 2,000,000 tons to a little over 1,000,000. Table I.—Exports of Indian Coal. 1914. 1915. ___________________ ___________________ Quantity. Value. Quantity. Value. Tons. £ Tons. £ Ceylon ................ 340,289... 203,810... 554,885 ... 343,202 Straits Settlements (in- cluding Labuan) .... 111,024... 61,230... 99,363... 55,475 Sumatra .............. 83,698... 47,838... 64,263 ... 38,688 Other countries ...... 42,933... 26,737... 33,290... 21,505 Total............ 577,944... 339,615... 751,801 ... 458,870 Coke ..................... 1,802... 1,509... 1,241 ... 1,327 Total of coal and coke 579,746... 341,124... 753,042 ... 460,197 The imports of coal were insignificant, amounting only to a little over 175,000 tons. Table II.—Imports of Coal, Coke and Patent Fuel during 1914 and 1915. 1914. 1915 Quantity \ c . Value. Quantity. Value. Australia (including Tons. £ Tons. £ New Zealand) 33,419.. . 36,543... 28,106 ... 35,958 Japan 32,232.. . 33,427... 18,069 ... 20,533 Natal 39,140.. . 47,066... 15,292 ... 16,437 Portuguese East Africa 58,742.. . 69,650... 52,312 ... 61,519 Transvaal 40,355... . 53,560... 26,448 ... 29,224 United Kingdom 156,863 229,160... 30,149 ... 45,948 Other countries 39,612.. . 49,865... 3,075 ... 3,303 Total.......... 400,363... 519,271... 173,451 ... 212,922 Coke ................... 12,729... 28,215... 10,241 ... 29,221 Patent fuel .......... 5,666... 6,116... 6,962... 11,007 Government stores .... 54,738... 83,904... 12,379 ... 30,635 Total........... 473,496... 637,506 .. 203,033 ... 283,785 The relative proportions of the output contributed by the Jharia and the Raniganj fields respectively were slightly different to that of recent years, the output of the Jharia field having fallen slightly in 1915, whereas that of Raniganj rose by over half a million tons; the respective percentages of the total output of India as regards these two coal fields were Jharia 53’44 and Raniganj 32’07 in 1915 as against 55’55 and 30 04 per cent, in the preceding year. Table III.—Provincial Production of Coal during THE YEARS 1914 AND 1915. Province. 1914. 1915. In" De" crease, crease. Tons. Tons. Tons. Tons. Assam 305,160.. . 311,296... 6,136... — Baluchistan 48,234.. 43,607... — 4,627 Bengal 4,424,557.. . 4.975.460...550,903... — Bihar and Orissa 10,661,062.. .10,718,155... 57,093... — Burma — 25... 25 .. — Central India 152,906.. 139,680... — ...13,226 Central Provinces 244,745.. . 253,118... 8,373.. — Hyderabad 555,991.. . 586,824... 30,833... — North-West Frontier Province 94.. 60... — ... 34 Punjab 54,303.. 57,911... 3,608... — Bajputana (Bikaner) 17,211.. 17,796... 585... — Total 16,464,263.. . 17,103,932... 657,556... 17,887 The percentage of coal production in the tertiary coal fields was only 2’52 of the total; a little lower than in the previous year. The chief tertiary coal field is that of Makum, the output of which rose from a little over 303,000 tons to 308,000 tons. There was a steady rise in the total number of persons employed in the industry, this now amounting to 160,086 ; the output per person employed, however, was again less than in the preceding year, having fallen from 108’76 tons in 1914 to 106’84 tons in the year under review. There were altogether 178 fatal accidents, the death-rate being 1’11 per 1,000 persons employ* d._______ * From the Records of the Geological Survey of India, Vol. xlvii., Part 3, 1916. ____________________________ Hull Coal Exports.—The official return of the exports of coal from Hull to foreign countries for the week ended November 28 is as follows :—Amsterdam, 203 tons; Chris- tiansund, 51; Gothenburg, 1,368; Havre, 241; Haugesund, 80; Harlingen, 481; Nantes, 1,357; Rotterdam, 751; Rouen, 2,042; Treport, 555; Trondhjem, 64; West Coast Africa, 1,056—total, 8,249 tons. Corresponding period November 1915—total, 56,019 tons. Corresponding period November 1914—total, 20,179 tons. These figures do not include bunker coal, shipments for the British Admiralty, nor the Allies’ Governments. FUEL BRIQUETTING IN THE UNITED STATES. In a report* issued by the United States Geological Survey, Mr. C. E. Lesher states that the manufacture of this type of fuel is still in its infancy in the United States, and probably many years will elapse before it assumes large proportions. The production in 1915 amounted to about 222,000 short tons, valued at about 1,000,000dels., and although there was a decrease, as compared with 1914, of 11 per cent, in quantity and 10 per cent, in value, the output exceeded that of all years prior to 1914. The process of briquetting low-grade material, and thus converting it into fuel suitable for higher uses, is practical conservation, and as such it deserves far more attention than it now receives. European countries, more thrifty in their use of coal, have developed the industry to large proportions, but in the United States only a beginning has been made. By many experi- ments, some of them costly, most of the mechanical difficulties have been solved, foreign machinery has been adapted to American coals, new machines have been devised, binders have been found, and the best size and shape of the product have been determined. The future growth of this industry in the United States depends on the development of markets for the product, and it is here that the greatest obstacles are met. The producing plants are so widely distributed over the country, and the total output is so small compared with that of other kinds of fuel, that the conditions affecting the market of each plant are more or less local and peculiar to its own area. In general, in the Eastern States, briquettes compete with anthracite as domestic fuel, and nearly all the output of the Eastern plants is manufactured from anthracite culm, or the fine sizes, such as buck- wheat. It appears that people in the Eastern cities, accustomed to the incomparable anthracite, have not taken very kindly to these briquettes, probably because of the volume of tarry smoke those made with coal tar as a binder give off when first ignited, and perhaps also because it has not been possible to offer them cheap enough, as compared with the domestic sizes of anthra- cite, to induce their extensive use. Being made from cheap anthracite, the briquettes contain more ash than the domestic sizes, which ash reduces the heat value of the fuel, even though it does not clinker in the furnace. The production of briquetted fuel in the United States in 1915 amounted to 221,537 short tons, valued at 1,035,716 dols., compared with 250,635 tons, valued at 1,154,678 dots., in 1914, a decrease of 29,098 tons, or 11 per cent., in quantity, and of 118,962dols., or 10 per cent., in value. The number of plants in operation is given as 16, of which seven were in the Eastern States, six in the Central States, and three in the Pacific Coast States. Of these plants, four used anthracite as a raw material; six, Arkansas semi-anthracite, West Virginia semi-bituminous or bituminous slack, or mixtures of them; one, a mixture of anthracite culm and bituminous slack; one, lignite; one, a mixture of lignite, anthracite culm, and bituminous slack; and two, oil gas residue. Five plants used coal tar pitch as a binder; two, tar mixed with other substances; three, asphaltic pitch; one, an organic binder; and one, petrolastic cement. No binder is required in briquetting carbon residues from oil gas works, or at the lignite plant in California. The total consumption of raw fuels used in making briquettes was in short tons :—Anthracite, culm and fine sizes, 53,118 tons; semi-anthracite, semi-bituminous, and bituminous slack, 123,944 tons; lignite and oil gas residue, 37,742 tons—total, 214,804 tons. The number of plants manufacturing briquettes in the Eastern States increased steadily from 1907 to 1911, but has decreased each year since that time. Likewise, the production, whirfffi in the period from 1907 to 1911 nearly trebled, in 1915 (output 33,541 tons) had decreased to 20,000 tons less than in 1907, and to 126,000 tons less than in 1911. In the Central States, where competition with anthra- cite is not so sharp, the production has increased every year since 1907, except 1913. Progress was gradual from 1907 to 1911, but in 1912 there was a large increase, and in 1914 and in 1915 the output was greater than in 1912. During the earlier period, particularly in 1909 and 1911, a number of the plants whose output is recorded were only in the experimental stage, and their small production brought down the general average. Nearly all the briquettes in the Central States are manu- factured from bituminous, semi-bituminous, or semi- anthracite, or mixtures of these kinds of coal. The plant of the Northern Briquetting Company, at Minot, North Dakota, uses the residue from brown lignite, which, after dry distillation in ovens of the type employed in making beehive coke, is mixed with a small quantity of bitu- minous slack, anthracite culm, and a binder composed of tar and low-grade flour. The plants in Wisconsin use bituminous slack and anthracite fines obtained from the re-screening plants of the coal storage docks at the head of the Lakes. On the Pacific coast the progress of the fuel briquetting industry has been steady during the last five years. There was no output in 1908 and 1909, but in 1911 the produc- tion (from three plants) was nearly 20,000 tons. In 1915 four plants manufactured 88,000 tons of briquettes, more than twice the output of the five plants in the Eastern States, and within 11,000 tons of the output at the six establishments in the Central region. In fact, owing to the increased activities of the Pacific Coast Coal Company, in Washington, and the addition of one new plant, in California, the product increased nearly two- thirds in 1915, as compared with 1914. * Mineral Resources of the United States, 1915, Part H.