164 THE COLLIERY GUARDIAN July 28, 1916. High-speed turbo exhausters are now very common in new plants, though the Otto Company has reverted to the drum type, placing it before the benzol scrubbers, and leaving most of the plant under suction. In by-product plant there is no really important improvement to record. The direct process has come to stay, and the different varieties are well known. There are two similar semi-direct processes, however, which are working successfully in England, and making excellent salt. They are both modified Mont Cenis processes,one run by the Semet-Solvay Company (Marr’s patent), the other by the Collin Company. The great point in connection with all direct and semi-direct pro- cesses is to avoid making too much mother liquor; and it is in the schemes to this end that the various designs differ. In the Solvay process, benzol is extracted from the gas before the ammonia. In this way the re-cooling of the gas after the saturator is avoided. This process is certainly a saving both in capital expenditure and in cool- ing water. After leaving the benzol scrubbers at 20 to 25 degs. Cent., the gas is led to the saturator, receiving on its way ammonia steam from the still which deals with the condensed liquor. The steam, on coming into contact with the gas, is suddenly cooled down to an equilibrium temperature of about 45 degs. Cent., and an amount of water fog is formed, which, if carried on to the saturator, would, by diluting the bath, tend to prevent the crystallisation of salt, and produce too much mother liquor. This water fog is therefore extracted from the gas by passing it through a special separator which is of the nature of a Pelouze tar extractor. This drains back into the still, and the gases saturated with water, but no longer super-saturated, pass forward to the acid bath. Owing to the heat liberated in the reaction, the gas temperature at the both outlet is 55 to 60 degs. Cent. The gas is still saturated, and, when it is considered that each cubic metre raised 10 degs. Cent, will carry away 63 grammes of additional water, it is obvious that there is no fear of excess mother liquor. In practice, water is added to the bath all the Runway Hoppt Wagon Section S nation time. The liquor feeding the still’is pre-heated in a heat exchanger by waste liquor coming from the still. In the Collin process the benzol scrubbers come after the saturators, a system which incolves re-cooling of the gas. The method of drying the gases coming from the still is also different. The vapour from the still can join the gas by either of two pipes, and the amount pass- ing each way can be regulated. One of the pipes leads straight to the gas main, whilst the other is a liquor heater which serves to dry the ammonia steam. This is simply a tubular heater, of different form altogether from the original Mont Cenis heater and dryer. In this way the ammonia steam is prevented from super- saturating the gas with water, and the water fog which is extracted in Marr’s process is, in this case, prevented from forming. The gas temperatures are practically identical in the two processes, and in each the rock salt difficulty has been overcome by using hot water every- where and in considerable quantities. xAlso it is well to have a lead steam pipe in the saturator, and give it a boil up once a week. In addition, the acid should be run in up to 18 per cent., worked down to 8 or 9 per cent., and then made up again. Continuous working at one acid strength is apt to lead to rock salt. In connection with the direct process, one of the problems arising where benzol is recovered is the removal of naphthalene during the cooling of the gas. After the saturator, direct-process gas, though perfectly free from tar, contains from 10 to 20 grammes of naph- thalene per cubic metre. Its temperature is about 80 degs. Cent., and though it can be cooled down to 55 in tubular coolers in the ordinary way, the coolers then rapidly become blocked with naphthalene. Three methods are used for overcoming this :— (1) Duplicate plant up to the benzol scrubbers, one part being steamed out while the other is in use. It is desirable to duplicate even the gas main to the scrubbers and to keep it as short as possible, and give it plenty of size, as it is always liable to block. (2) The Otto method of direct cooling in a tower by contact water sprays. The quantity of waiter required is very considerable, but where this is available, the contact method is the simplest and best. The naph- thalene is washed down in granular form, and may be skimmed off the water as it flows through troughs. (3) Simon Carves Limited have patented a process which consists in spraying the gases with creosote oil which dissolves the naphthalene, and the oil when saturated is pumped into crystallising pans, from which the liquid oil is subsequently run off and used again. The circulating oil naturally mixes with the condensings from the gas, and the complete and continuous separa- tion of the oil and water in special tanks is part of the process. In warm weather the naphthalene does not separate very well, but the process is quite effective. For the rest, our recent changes are but small matters, and may be summed up very shortly. Ammonium Chloride. Where the coal contains sodium chloride, a good deal of the ammonia can be recovered as ammonium chloride, sometimes 30 per cent, of the salt made being in this form. The direct process lends itself well to the recovery of ammonia in this form, as in the washing of the- gases with hot liquor the chloride is extracted, the saturated solution being evaporated to obtain a crude salt. The salt, a fair colour at first, soon turns black; but if the dark salt is heated for some time to a temperature just short of volatilisation, and re-dissolved in water, the carbonaceous matter is rendered insoluble, and, after settling and filtering, a clear liquid is obtained, from which a permanently white salt is produced by evapor- ation. In another process the same result is produced in one evaporation. Naphthalene. Mr. Middleton, of Consett, has rigged up a useful little subliming plant for treating dirty naphthalene. It con- sists simply of two old Lancashire boiler tubes, 3 ft. diameter. A bridge is built in the usual position, and a few coils of steam pipe, laid in the furnace area, serve to volatilise the naphthalene, which sublimes over into the rest of the tube, and nearly fills it up. xA small outlet is left at the other end for observation. After the first sublimation, the naphthalene is slightly yellow, but on re-subliming a pure white product is obtained. No live steam is used. The number of by-products manufactured at coke works is being extended. Carbolic and cresylic acids and pure naphthalene arc made at one plant i'n Durham. Pure benzene and pure toluene are made at certain places, but most coke works refineries go no further than “ Government benzol ” and toluol containing 75 per cent, toluene. More pure products ought to be manufactured. Pyridine is still wasted on all coke works; also cyanogen. Briquettes. The making of coke ballast into briquettes is a useful line, plant for which is to be started at Crook, Durham. Seven per cent, of pitch and 3 per cent. tar are to be used. Pitch Coking. This has been tried at several plants with varying success. Some have used 7 or 8 per cent, of pitch and taken no harm, while others find the ovens stick if only 2 or 3 per cent, is used. Evidently one should proceed cautiously in this matter when experimenting, as the result appears to depend on the nature of the coal. Dry Cleaning. Another interesting point is the “dry cleaner’’ in use at New Brancepeth. It is found that dry coal, when crushed in an ordinary bar type disintegrator, may be divided into two qualities by means of a riddle. The crushed coal is passed through a screen with yL- in. holes. The coal passing through will contain 6 per cent, ash, whilst the coarser part contains 30 or 40 per cent., and is returned to the washer. Lampblack. This is made from surplus gas at one plant, but the exact method is kept a close secret. It is understood that a number of gas jets burn under a revolving plate, the deposited carbon being scraped off. American Coaling Station Scheme. — The Tidewater Securities, having obtained power to build a bridge from Cedar Point to Dauphin Island, in Mobile Bay, is expected to develop Dauphin Island as a coaling station for the largest vessels. Arrangements have been made for dredging the bay, which will ultimately have both rail and water com- munication with the Alabama coal fields. Peat for Locomotives. — A plan is being worked out in Sweden with a view to operating the Swedish State rail- ways by peat powder in place of coal. The committee which has been investigating the matter has made a favourable report, and has requested a large appropriation from the Government for the erection of a peat powder factory at one of the large peat bogs, and for the use of enough locomotives for peat powder, so that all the trains on one line may use this fuel The peat powder is found to be very efficient and practical, with a fuel value compared with that of coal of about two to three, though a higher ratio is expected when the peat powder is in regular use. It is estimated, basing the calculation on the lowest figures, that the cost of peat powder per ton will be about two-thirds that of coal. INDIAN AND COLONIAL NOTES. Africa. Wastefulness in Natal.—In a paper read at a meeting of the Engineering Section of the Natal Society for the Advance- ment of Science and Arts, Mr. J. Wilson, of the Glencoe Collieries, observed that the coals of Natal included prac- tically all known varieties. It was quite common to find a steam-raising plant burning under forced draught conditions an excellent coal for gas making, or one which would be highly suitable for household purposes, a coal that would give excellent results under natural draught. The South African railways bought all kinds of coal for one purpose only, without regard to its suitability for the excessive draught conditions which occurred in the furnace of a loco- motive mounting an incline, and that, added Mr. Wilson, was one of the reasons why the efficiency obtained by the railways was so very low. He thought that it would be quite safe to assume that the percentage of -work extracted from coal by the railways did not exceed 25 per cent, of its work content, and that 75 per cent, of the coal bought and used became a total loss. This loss was the more serious when it was stated that the economical working of the railways was of paramount importance to everyone in the province. Rail- way rates and railage were the great handicap to the progress of all industrial concerns, and in certain producing centres the railage cost was seven times more than the pits’ mouth price of the coal. Electrification of the railways might solve the problem to a considerable extent. Mr. Wilson referred to the advantages of electricity over steam, but considered that financial considerations would preclude any change in our present system. It was, therefore, most desirable that greater efficiency should be obtained from the coal used, in order that cheaper transport could be possible to enable Natal coal to extend its activities. Natal coals were very friable, and the layers rich in carbon were the softest part. In mining the large percentage of smalls made was mostly com- posed of the best portions of the seams, and to a great extent that material found its way to the waste dump, where the large accumulations were evidence of enormous wastage of a valuable asset. There was no difference in the work content, or calorific power of the larger coal and the dross, but the latter could not be applied except in specially constituted grates. These grates were in use at the Durban Power Station and at some of the sugar mills, which consequently enjoyed an advantage over their rivals owing to the fact that dross coal was so much cheaper than large coal. South Africa had a large home consumption for many of the products obtained from waste coal, and the lecturer mentioned motor spirits and sulphate of ammonia, both of which came under that category. It was probably, he thought, the high cost of erecting plants at the mines, and the heavy railway charges, which had deterred companies from entering that field of enterprise. However, the development of the low temperature high vacuum retort would in the near future solve the problem of capital expenditure, and that method would enable collieries to produce motor spirits at prices that would render the importation of petrol both unnecessary and economically impossible. He ventured to predict that within two years of the cessation of war the production of motor spirits and other valuable products from our waste coal would be accomplished, and be the foundation of a new era of prosperity for Natal. Australia. Only 9,670 tons of coal were exported from Newcastle to oversea ports during the first week in June, 1,643 tons to Hawaii, 1,074 tons to Sandwich Islands, 823 tons to Fiji, and balance as bunkers to three other countries. The Waterside Workers’ Union in Melbourne demanded the abolition of contract system of unloading coal heretofore carried out under the arbitration award of Is. 4d. per ton, refusing to handle cargo until paid at an hourly rate of Is. 9d. to 2s. 6d. per hour. In the first quarter of 1916 coal exports from New South Wales to Australasian and other ports were 884,453 tons, valued at £478,425, which included 130,425 tons of bunker coal valued at £78,424. These figures show a decrease of £166,371 on those recorded for the similar period last year. Canada. A serious factor in the reduction of coal outputs is the very drastic requisitioning of coal-carrying steamers by the Admi- ralty. The large coal companies of Nova Scotia have made a practice of chartering vessels on long-term seasonal con- tracts. These vessels have been especially built for the St. Lawrence coal-carrying trade, and include the finest and most capacious coal-freighters afloat. The charter parties call for delivery of these, vessels on charter during the season of open navigation, and in some instances cover periods of 18 years. These vessels, being excellently suited for the needs of the Admiralty, have been most freely requisitioned, but the action of tire Admiralty has borne very heavily upon the coal companies. With the exception of the coal used locally at the mines, and the coal consumption of the Cape Breton steel works, all the coal mined in Cape Breton Island is exported to market by water. The selling price of coal under the usual contracts will not bear the cost of rail trans- portation, even were that physically possible, which it is not; nor will it allow the delivery of the coal by vessels chartered at current market rates. During the winter of 1915-1916 the lack of shipping tonnage caused a good deal of idle time at the collieries, and this in its turn moved many workmen to look for work elsewhere. The resulting situation bids fair to have grave results in the districts where Nova Scotian coal has been sold in the past. Some of the shortage will be made up by American coal imports, but it cannot all be made up, and a shortage of fuel supply in Montreal and the vicinity is certain to assume serious proportions during the winter. Apart from the injury to the chief market for Nova Scotian coal, it is certainly far from desirable that Canadian money at this time should be expended in the purchase of American coal, and that the production of coal in Nova Scotia should decline so alarmingly as it is doing at the present time. It appears quite probable that the coal output of Nova Scotia during 1916 will be one and a quarter million tons below the capa- city of the collieries. The great bulk of the coal is being used for war purposes.