July 28, 1916. THE COLLIERY GUARDIAN 165 CURRENT SCIENCE Powdered Fuel for Locomotives. A report submitted 'to the International Railway Fuel Association, Chicago, states that the Chicago and North- Western Railway has equipped and is now’ operating in its regular passenger train service between Chicago and Milwaukee an existing Atlantic type passenger loco- motive, and the Delaware and Hudson Company has just put into freight service a new consolidation locomotive, probably the largest of this type in the w-orld. The Dela- ware and Hudson Company is also installing a complete fuel drying, pulverising, storage, and disbursing plant, and equipping their stationary boilers at Olyphant, Pennsylvania, for burning the waste tailings from anthra- cite culm banks. The Missouri, Kansas and Texas Rail- way is installing a complete pulverised fuel preparing plant at Parsons, Kansas, and applying equipment for burning pulverised coal and lignite in its stationary boilers and locomotives. Various other steam railways, among which may be mentioned the Atchison, Topeka and Santa Fe, Grand Trunk, Southern Pacific, Kansas City Southern, Chicago Junction, and Central Railway of Brazil, are now considering the use of pulverised fuel for locomotive service, the last-named having already decided to adopt it after an exhaustive three months’ investigation made in the United States. The usual methods of burning pulverised fuel necessi- tate the use of steam, air, or mechanical contrivances for projecting the fuel, or a mixture of fuel and air, into the furnace. When applied to steam generators this process has resulted in failure due to the severe effect of concen- trated heat on the firebrick and firebox. The more recent process, as applied to the Chicago and North-Western Railway and other steam locomotives, provides for a combustible mixture of fuel and air being automatically induced or drawn into the firebox by means of the front end draught, and its perfect combustion in suspension without any concentration of heat, due to the fact that the combustion flameway and the products of combustion are at all times being drawn toward an opening and thereby avoid any impinging action. Furthermore, this process is divided into three stages, i.e., conveying and commingling of fuel and air, gasify- ing of combustible mixture, and perfecting of the com- bustion in the final high temperature heat zone, all of which ensures completion of the combustion process. From observations taken with fuels of different kinds and degrees of moisture and fineness, in every case the smoke-box gas analyses will average between 13 and 14 per cent, of C02 when coal is fired at the relatively low rate of about 3,000 lb. per hour, -and is increased to 15 and 16 per cent, of C02 as the rate of combustion increases, so that there is no falling off in the efficiency, as obtains when coarse coal is fired on grates. At the same time, the smoke-box temperatures are maintained between 425 and 500 degs. Fahr. Summing up the results that are being obtained in locomotive service, these may be stated as :—(1) Smoke- less, sparkless, and cinderless operation; (2) mainten- ance of maximum boiler pressure within a uniform average variation of 31b. without popping; (3) an increase of from 7| to 15 per cent, in boiler efficiency as compared with burning lump coal on grates; (4) saving of from 15 to 30 per cent, in fuel of equivalent heat value fired; (5) enlarged exhaust nozzle area, resulting in greater drawbar pull and smoother working of locomotive; (6) elimination of ashpit delays, facilities and expense and reduction in time required for, and ease in firing up; (7) maintenance of a relatively high degree of superheated steam; (8) no accumulation of cinders, soot, or ashes in superheater or boiler flues, smokebox, or on superheater elements; (9) no punishment or over- heating of firebox, new or old sheets, seams, rivets, patch bolts, stay or flue heads; (10) elimination of arduous manual labour for building, cleaning, and dumping fires; (11) avoids expense and annoyance of providing various sizes and kinds of fuels; (12) eliminates the necessity of front end and ash pan inspection and for special fuels, firing tools and appliances for building fires and for stoking and cleaning fires; (13) equal provision with engineer for fireman to observe signals and track, thus reducing liability of accident. The committee is of the opinion that the effectiveness and utility of the use of fuel in pulverised form has been demonstrated from the past year’s development, and that the progress in the use of this method of stoking and burning bituminous and anthracite coals and lignites for generating power, heat, and light on railways will be quite marked from now on. Cause and Effect in By-Product Coking. From the point of view of operating troubles, coke must be made the prime consideration. In the majority of cases the choice of coal is limited, and the conditions of w’orking have to be so arranged as to deal suitably with the particular class of coal available. Where more than one quality is used, and in varying proportions, there must, of necessity, be a variation in method if the best results are to be attained. Experience shows that the percentage of added moisture, for instance, will greatly influence the quality of the coke produced. In some cases it is not sufficiently realised that a small difference in the ash content of the coal seriously affects the quality of the coke. In a recent instance, !a fairly average blast-furnace coke was produced from a coal containing about 7 per cent, of ash. Owing to a break- down, the washing arrangement was affected, and the average ash content rose to about 10 per cent. The effect on the coke was immediately noticeable. Instead of being hard and compact, it was much softer, more friable, and the percentage of breeze produced was almost doubled. A return to normal washing conditions was followed by a return to the production of the original quality of coke. AND TECHNOLOGY. The quantity of moisture in the coal as charged into the oven has also a serious effect, because excessive moisture results in the production of an easily friable coke. It has been shown by actual experiments that with normal conditions the time of carbonisation of a charge is increased something like 20 per cent, by increasing the moisture content from about 9 to 15 per cent. From the point of view of the effect on the quality of coke, the most probably explanation is the following :— The carbonisation of the charge proceeds from the outside towards the centre. With a high percentage of moisture in the coal, when the outer layers 'are thoroughly burned off, the coal still remaining in the interior of the charge will contain a large amount of water. This is gradually converted into steam, and, in passing through the red-hot coke causes disruption of the structure and ultimate breakage. Here, again, the improvement is most marked if the moisture is reduced to a reasonable limit. If, however, by any chance there should occur a combination of excessive ash content and excessive moisture content, the result is disastrous, the coke produced being very inferior. A still further ill effect of an increased moisture con- tent is that the outer portion of the charge has to remain in the oven for a considerable period after it is quite carbonised, and this, again, tends to cause the coke to break up more. The practice of allowing the coke to remain in the oven for a few hours after the charge is quite burned off, is claimed to produce a harder coke; but prolonged heating after the charge is burned off is both wasteful and harmful. If the ovens are being worked at all on the hot side, very great care is neces- sary in the regulation of the heat. After the charge is quite carbonised, very little heat is being absorbed, so that the gas burning in the flues has only to supply sufficient heat to balance radiation losses. Hence neglect to reduce the gas supply to the walls o>f an oven which is burned off frequently results in an excessive temperature in the walls, and, in some cases, in fusion of the brickwork. From all points of view it is advis- able so to arrange the heats that each oven can be dis- charged within an hour of being turned off, as in this way regularity of heating and working can be best main- tained. Obviously, if the gas has to be reduced in the walls, it is more difficult to maintain constant tempera- tures. Again, when an oven is only partially burned off, a large volume of gas is being given off, so that a pressure is maintained in the oven. When the charge is carbonised, no gas is being evolved, and it may be that there is a suction on the oven. This eventually results in hot ascension pipes and a hot gas main; then, when the oven is again charged, the hot ascension pipe is liable to bring about the commencement of pitch trouble in the main.—Gas World. Potash from Blast-Furnaces. In discussing the possibility of recovering potash from the blast furnace, Mr. C. Catlett (Manufacturers Record) says that furnace slag may be assumed to contain 0-4 per cent, potash (K2O) on the average, the flux containing 0-3 per cent., and the coke 0-3. Iron ores are variable, the leaner, more siliceous ores containing between 1-50 per cent, and 2 per cent. A rough calculation on a normal mixture would give : Potash from 2| tons ore, 0-035; from 1-Jtons coke, 0-0048; from 1-2 tons limestone, 0-0036 per ton iron. Of this there is lost in slag 0-0060 ton, leaving 0-0374 per ton of iron, probably all as cyanide in the gas, and corresponding to about the same as reported by Sir Lowthian Bell, viz., 6 tons potassium cyanide per 100 tons of iron produced. The potash is apt to follow the siliceous impurities, so that those furnaces which are at a disadvantage on account of what is spoken of as a low- grade material may by the utilisation of the by-products produce iron cheaper than other furnaces which are at present blessed with the purest of raw material. If the gas is not created till it is burnt in the stoves and under the boilers, the cyanide would be destroyed and the potash would no doubt occur as the carbonate or sulphate. There is no limit to the demand for potash at a price. It is probable that large quantities could not be sold for more than 300dols. per ton (based on pure K2O), even though much higher prices are paid at present for it. Even on this basis the potash alone saved from such a furnace, ignoring cyanide, lead or zinc, would be easily saleable to-day at over 7 dels, per ton of iron pro- duced, and at pre-war prices between Idol, and 2 dols. per ton of iron. Below are the results of analyses of the dust collected in the down-comer, stoves and back of the boilers. It is noted that the higher temperature of the stoves prevents the potash being deposited. In old times when lower temperatures were the rule it is probable the stove dust ran higher. The material in the down-comer represents largely coke breeze and fine ore with very little of the fume. Water Soluble Potash (K2O) from Furnace Dust. Down- comer. Boilers. Stoves. Flue to stack. Slag. Per cent. Per cent. Per cent. Per cent. Per cent. 050 . .. 7’35 .. 1*45 . — — 0*48 . .. 7*40 .. 1’33 . — 0’36* 0-02 . .. 0 009 .. 0’02 . 1T8 — — .. 2*75 .. 1'42 . — — 0-23 : .. 1*32 .. 2’27 . — — 0*57 . .. 0-87 .. 0-80 . — — 0’30 . .. 5T0 .. 1*73 . J — — 7’00% f * Total potash (K2O). f Average sample boilers and stoves. In addition to the water-soluble, there were consider- able amounts of acid soluble potash. These figures mean very little, except that the potash is present and in such form that a slight slowing of the speed or lowering of the temperature of the gases causes precipitation to commence. Not only does the dust which is thus incidentally collected represent but a small fraction of the potash in the gases, but it is far less pure and far less concentrated than that which is at present lost. It has long been known that dust and fume could be precipitated from gases by means of an electric current of high intensity, and in the last few years the method has been used so extensively and in so many directions as to leave no doubt that it can successfully be applied to the gases from the blast furnace. From a furnace operat- ing standpoint the only thing absolutely necessary is .to reduce the temperature of the gases as low as convenient, but not necessarily lower than should be the case any- how in an efficiently operated furnace, and to pass them through chambers of such cross section that the velocity will be reduced. In other words, it is easy to remove the fumes and dust from the gases without interfering in any way with the operation of the furnace. The invest- ment would be moderate and the cost of operation of the potash recovery plant would be low, while the gases would be improved for use in the stoves. Controlling Coal Dust. In Bulletin 102 of the U.S. Bureau of Mines, Messrs. J. K. Clement and L. A. Scholl, jun., give the results of a detailed study of the dusts of Illinois coal mines, for the purpose of investigating the quantity and character of the dusts produced in the mines of the State, in order that proper methods might be devised for preventing dust explosions. The tests were made in a laboratory apparatus, by the methods devised by Dr. J. C. W. Frazer. More than 500 samples of dust from 100 repre- sentative Illinois mines were tested. The results lead to the following conclusions :— (1) The coals of Illinois when ground to a sufficient degree of fineness yield highly inflammable dusts which when suspended in air may give rise to violent explosions. (2) In the majority of the mines of the State the dusts adhering to the ribs are inflammable. In about one- fourth of the mines the quantity of rib dusts present in the entries is sufficient to form an explosive mixture with air. (3) Most of the road dusts are inflammable when ground to a sufficient degree of fineness. For the purposes of the co-operative mining investiga- tion, the State was divided into eight districts, the mines working the same seam being grouped together as far as possible. The dusts of the various districts were found to differ appreciably from one another, both in quantity and in character, corresponding to differences in the character of the coal and in the mining methods and conditions. For example, in District 1, in which the longwall system of mining is used, the dust samples collected in the entries were exceptionally high in ash J and low in inflammability. The road dusts from District 8, which includes Edga.il and Vermilion counties, showed high ash content anew were less inflammable than those of any of the otheri- districts. In other districts, especially those of the southern part of the state, the rib dusts and the road dusts were found to be very inflammable. TRADE AND THE WAR. Messrs. Head, Wrightson, and Company Limited, Teesdale Ironworks, Thornaby, applied in the Patents Court for a Board of Trade licence to manufacture under four German policy patents improvements in blastfurnaces, and the con- troller decided in their favour. The London Gazette announces that at the end of three months, unless cause is shown to the contrary, the names of Charbonite (1909) Limited, Gellyonenen Collieries Limited, Gwyn Mines (Merioneth) Limited, Methane Limited, Petro- lite (1908) Limited, St. Vincent Colliery (Forest of Dean) Limited, and Smoke Consumption (Cowper-Coles Patents) Limited, will be struck off the register and the companies dissolved. The Commercial Intelligence Branch of the Board of Trade, 73, Basinghall-street, E.C., has received an enquiry from an Australian contractor (reference number, 218), who desires agencies for gas-recording calorimeters; from a Sydney importer (reference number, 219), who desires to represent British manufacturers of rustless hand and edge tools; and from Australian agents who desire to represent British manu- facturers of mining and railway material and machinery of all kinds. Some British manufacturers are enquiring for machines for cutting and pressing peat for fuel, for spring steel for clock springs and for cheap files. The Board of Trade has ordered the winding up of the business of F. M. Frye and Company, tool makers, etc., 46, Upper Thames-street, London, and M. C. Wedekind and Company Limited, dealers in old iron and steel, 6, Lloyds- avenue, London. An amended notice mentions the winding up of the British Huhn Metallic Packing Company Limited, Snowdon’s-wharf, Millwall. A consolidated statutory list (No. 5a) has been issued in connection with the Trading with the Enemy Act, 1915. British firms are prohibited from trading with anyone mentioned in the list, which is issued at the price of 2d. by Messrs. Wyman and Sons Limited, 29, Bream’s-builflings, London, E.C. Coal seams which are now being opened up near South- port, on the south coast, and at Seymour River, on the east coast of Tasmania, are claimed to be of good quality. The location of the south coast coal field is within a mile and a-half of a deep-water jetty, and is distant from Hobart 50 miles. The Minister of Munitions has appointed a Committee to consider and recommend as to arrangements to be made for the release of workmen for holidays in relays, so as to main- tain without interruption an adequate output of munitions. Mr. A. Henderson, M.P., is the chairman, and Mr. R. H. Crooke, Ministry of Munitions. 6, Whitehall-gardens, S.W., is secretary.