416 THE COLLIERY GUARDIAN. August 21, 1914. ciently heating the tar is liable, therefore, to cause much local offence unless effected under conditions providing for the condensation of the vapours and the proper treatment of the noxious gases driven off during this operation. The noxious gases evolved in “ tar ” works have been satisfactorily dealt with during the year. As formerly, these noxious gases were dealt with by combustion under proper safeguards, absorption in oxide of iron purifiers, absorption in lime purifiers, or absorption in purifiers containing a mixture of oxide of iron and lime. In this report on District No. 2 (North of England), Mr. E. Morley Fletcher states that the number of works registered at the close of the year for the manu- facture of sulphate of ammonia is 85, an increase of four during the year. Of these new works, three were coke oven works with recovery of by-products. The fourth is a gas works where direct recovery of ammonia from the crude coal gas by washing with weak sul- phuric acid is adopted. This is the first plant of the kind in the district. A continuous ammonia still has replaced an intermittent plant at one works, leaving only four works where the intermittent process is now in use. There has been a 17 per cent, increase in the amount of sulphate of ammonia made over that for the previous year, but this is in part due to the coal strike in 1912, which caused a diminution in output for that year. Deporting on District No. 4 (North and East Lancashire, and part of Yorkshire), Mr. H. J. Bailey says there were 57 works in which the gas liquor and sulphate and muriate of ammonia processes were carried on during the past year. Of these, 50 were registered for the manufacture of sulphate and muriate of ammonia, and 11 for the manufacture of concentrated gas liquor. The proportion of ammonia distilled by the continuous process was 97-2 per cent, of the total. Ammonia liquor produced at coke oven plants has been distilled at five works; at two of these liquor ammonia only is produced, at two the Claus process is still in use, and at the one works where the foul gases are destroyed by combustion the average total acidity of the chimney gases was 0*83 grain per cu. ft. expressed in terms of SO3. One new large coke oven plant has come into operation during the year in this district, where the plant erected for the distillation of ammonia liquor is of an efficient and up-to-date type. At two of the coke oven plants condensers which were leaky were renewed during the past year. In the East Midland District, Mr. R. D. Littlefield says there are 61 works registered under this heading, of which eight are gas liquor works. The complete direct ammonia absorption plant for dealing with coke oven gas, referred to in the report for 1912, was put in operation during the year under review. Works generally have been busy, and in all cases plant has been maintained in good order. In works making sul- phate of ammonia, the proportion made by the con- tinuous process amounted to 99-5 per cent, of the total. Calculating on the basis of the sulphate of ammonia equivalent of the total gas Ijquor dealt with in the dis- trict during the year, there is an increase amounting to 17-8 per cent, over that similarly produced during the preceding year. Separating the amount of sulphate made under headings “ ordinary gas works ” and “ coke oven works,” there is a decrease of 3-4 per cent, in the former class, and an increase of 40-9 per cent, in the latter. Coke oven plants are now responsible for con- siderably more than half the total sulphate of ammonia made in this district, and it seems probable that the output from this class of plant will increase in the near future. Several new works are in course of building, and in a number of cases additions have been made to the existing ovens. In District No. 5 (South Midland and Norfolk), Mr. Edward Jackson reports that the number of works registered where either sulphate, chloride, or carbonate of ammonia is manufactured, or gas liquor concentrated was 114. At 107 works sulphate of ammonia is pro- duced, at six works chloride of ammonia, and at 12 others gas liquor is concentrated. Thus 125 plants are under inspection for the three processes referred to. Only two new works for sulphate of ammonia manu- facture have been registered during the year. At both of these works plants for the direct process have been put into operation. One is in connection with coke ovens, and the hot gases from the ovens are passed through sulphuric acid of sufficient gravity to deposit the sulphate of ammonia crystals in the saturator. At the other works the plant is at an ordinary gas works, and the coal gas, after tar extraction, is washed with a weak (1-0 to 2-0 per cent.) sulphuric acid to arrest the ammonia. The resulting solution of the sulphate is then evaporated to the salting point. The crystals pro- duced by both these processes are of a very good quality. It is interesting to be able to report that this direct recovery of ammonia at the ordinary gas works has made further progress in the district. Two more plants have been erected this year, in addition to the one referred to in last year’s report as working satis- factorily, and a fourth is almost completed. The erec- tion of by-product coke ovens has still further increased during the year. Important additions have to be noted at works already registered. But only one new works has come into the list as yet. At these works also the “ direct ” and also “ semi-direct ” processes of sulphate of ammonia production are increasing in favour. In the “ direct ” process the hot oven gases are passed into the sulphuric acid. With the “ semi-direct ” the gases are cooled to extract tar and then heated up again before passing into the sulphuric acid. By the latter plan there is some ammoniacal liquor to distil, i.e., the virgin liquor collected with the tar; but the noxious spent liquor from the still is greatly reduced in quantity, some operators say by one-half, even by this method, as compared with the old plan of arresting all the ammonia with water and then distilling the ammo- niacal liquor. There are 23 by-product coke oven plants in the district where sulphate of ammonia is manufactured. At five works chloride of ammonia is also produced, and at one work gas liquor is concen- trated. in addition to the manufacture of sulphate and chloride. This year the sulphate of ammonia produced from coke ovens reaches 42-y per cent, of the total make in the district. There has been a considerable increase in the production of ammonia compounds in the dis- trict over the previous year amounting to 17*4 per cent, on the 1912 figures. Coke ovens are responsible for over 7 0 per cent, of the increase, gas works contribute zO per cent., and the remaining 10 per cent, of the increased production is divided between producer plants, iron works, and coal carbonising plants. Coke ovens now account for nearly one-half the production. lieporting on the South and South-West of England, Dr. Alfred C. Fryer says the number of works regis- tered at the close of the year where either ammonium sulphate or ammonium chloride is manufactured was 105. Two new works have been registered this year for sulphate of ammonia manufacture. These plants have continuous stills, hand-fishing saturators, suitable condensers, and oxide of iron purifiers. Two small works have discontinued to make sulphate of ammonia, and the plant at one of them has been dismantled. Four works have built new sulphate houses and erected new stills in place of more antiquated arrangements. New saturators have replaced old ones at seven of the plants, and four works have built new oxide of iron purifiers. It cannot be impressed too strongly, says Dr. Try er, on the minds of those managers of small gas under- takings who are not chemists that every ton of coal carbonised in this country should produce from 25 to 30 lb. of sulphate of ammonia, and that if due care is exercised throughout the whole operation this produc- tion should be realised. Inefficient washers, leaky store tanks, and poorly constructed sulphate of ammonia s Gills carelessly worked are all points where serious loss of ammonia may take place. It is well for them to test their gas liquor for ammonia, both free and fixed, and it is most desirable to ascertain that the fume pipe from the saturator and the effluent from the still or boiler is not removing some of it to the drains. A thorougnly efficient still can reduce the loss to a decimal point per cent. This, however, cannot be done with a hand-fired boiler, as it is a well-known fact that steam displaces ammonia from a liquid more easily than by a closed steam coil or external firing. In selecting a still it is prudent for them to err on the safe side, as wasteful work always results when the still is driven beyond its capacity. Variations of steam are inevitable and loss of ammonia always results owing to inefficient boiling. At one or two works in this district a ther- mometer is fitted on the liquor pipe at the outlet of the superheater so that any decrease in steam temperature may be at once indicated and correction made. Com- paratively few managers of small works have grasped the fact that 40 lb. of pure caustic soda, 53 lb. of soda ash, or 37 lb. of pure slaked lime cannot liberate more than 17 lb. of fixed ammonia, and that a certain allow- ance must always be made for extraneous substances, and also for moisture in both caustic soda and lime. It is frequently calculated that gas liquor contains 20 per- cent. of fixed ammonia, and if this is not all displaced by an alkali the loss must be serious. The alkali used is either lime, caustic soda, or soda ash, and the latter is now employed at several works in the district. It requires a longer contact with the liquid, but it is cheaper and much easier to manipulate than caustic soda. Some few gas works in the South and South- West of England dispose locally of their make of sul- phate of ammonia, yet by far the larger bulk manu- factured is sent abroad, although nearly all the works are situated in towns surrounded by agricultural districts. Statistics inform us that in England the consumption of sulphate of ammonia is only 24 per cent, of the production, while the United States, France, and Belgium consume more sulphate than they produce, and Germany, with a manufacture of about 500,000 tons, utilises 84 per cent, of her very large output. In South Wales and Monmouthshire, according to Dr. T. Lewis Bailey, the number of sulphate and muriate of ammonia works has increased to 24, the new registrations including two coke oven by-product plants and three sulphate of ammonia plants at gas works. Two new coke oven by-product plants also are nearing completion. The amount of ammonium salts produced in this district during 1913 constitutes a record for both gas works and coke ovens. The total made was 26 per cent, more than the previous highest, which was in 1911, and 31 per cent, more than in 1912; the production of the latter year was, however, reduced by colliers’ strikes. The direct methods of making sul- phate of ammonia at gas works have not yet made their appearance in South Wales, though there are small gas works where one would imagine that such an installa- tion would be of great advantage and a source of profit, especially in the western portions of the district, where considerable quantities of ammonium compounds in the form of gas liquor are run to waste. This year, however, two coke oven by-product plants have com- menced work, in which direct methods of sulphate of ammonia manufacture are employed, and up to the present all appears to be working nicely, and salt of excellent appearance is produced. The concentration or distillation of gas liquor for the manufacture of various ammoniacal compounds is carried on at 96 works in the Eastern district. The products consist chiefly of sulphate of ammonia, but include carbonate, chloride, and nitrate of ammonia, liquid (concentrated and refined) and anhydrous ammonia. An increase is shown in the total products of some 4,600 tons (in terms of sulphate) on the figure for the previous year. The gas works belonging to statutory companies and local authorities produced 91*2 per cent, of the products, and the balance has been made in the works of private firms. At three works the crude gas liquor is concentrated by distillation to about 80 oz. strength to facilitate carriage to a central works, where it is again distilled for various products. The intermittent process of distillation now only survives at five works, and 99-2 per cent, of the gas liquor has been treated by continuous distillation methods. The whole of the saturator gases evolved from the extensive gas liquor distillation plants of the three chief gas com- panies supplying the metropolitan area is used direct for the manufacture of sulphuric acid. The proportion thus disposed of is 63-3 per cent, of the whole, and this large quantity of sulphur material is again utilised for subsequent combination with ammonia. The Claus sulphur recovery process remains in use at seven works, and deals with 14-4 per cent, of the total saturator gases. The sulphur recovered is either used for acid manufacture, or more generally for the recovery of cyanogen compounds from the crude coal gas by extraction as sulphocyanide of ammonia. The sulphur recovery process is less popular than formerly, partly owing to the comparatively short life of the brick depositing chambers, and also to the fact that the treatment of large quantities of sulphuretted hydrogen by oxide purification is better understood than formerly. The use of a sheet-lead depositing chamber in place of brickwork has not, unfortunately, extended, although its merits in resisting the destructive action of the acid gases has been well proved. Treatment of the saturator gases by absorption in hydrated oxide of iron is most universally adopted and is practised at 65 of the 90 works of this class, and the proportion of gases so treated amounts to 13-7 per cent. The adaptability of the oxide-heap system for large works is now much better understood, but a considerable amount of open ground fepace is essential if a large quantity of gas is to be treated economically. The system again is useful for cleaning and working up to high sulphur content oxide which has become inert in the carburetted water gas purifiers through impregnation with oil. The heat of chemical action taking place in an exposed heap of such contaminated oxide will in time entirely remove the oil by volatilisation. The “ combustion neutralisa- tion ” method of treatment of gases continues in use at 10 works, and accounts for 7-7 per cent, of the total. At three works the saturator gases are passed to the crude coal gas main, and thence to the purifiers. Com- bustion of foul saturator gases in retort or boiler flues survives at only two. One is a very small gas works, and the other treats ammoniacal liquor recovered in the manufacture of bone charcoal. Mr. J. W. Young, Chief Inspector for Scotland, states that the production of salts of ammonia (expressed as sulphate) was as follows :—Gas works, 21,626 tons; iron works, 18,554 tons; shale works, 63,061 tons; producer gas, coke, and carbonising works, 22,205 tons—total, 125,446 tons, against 120,347 tons in 1912. The output of pitch was 174,884 tons, against 151,345 tons. . The most marked change here is the yield of sulphate of ammonia from the iron works, and of pitch. There were 119 works registered for the gas liquor, sulphate and muriate of ammonia processes last year, as iwo new works were started. There is tendency for gas firing to replace solid fuel, on account of the value of the recovered residuals. At the coke ovens using the direct sulphate of ammonia process yields more abun- dant than formerly are heard of. There is no present example of this system applied to the manufacture of illuminating gas. The influence of the vertical gas retort, of which now there are frequent installations, it is too early as yet to recognise by any decisive change in the character of by-products. A case of partial poisoning by inhalation was reported from one of the shale works : the man affected had been cleaning a sul- phate of ammonia saturator, laid idle for repair. Precautions suitable in washing and ventilation had been beforehand taken. The causes of poisoning were obscure, and although more readily to be explained by the evolution of arseniuretted hydrogen, to which his symptoms were attributed by the physician, it is uncertain that all the conditions necessary for such evolution were present. A valuable warning has, how- ever, resulted against the use of new and galvanised- iron pails to contain refuse which has been in contact with arseniferous acid. A stout wooden bucket is much safer and also more durable. In continuance of the table presented in recent annual reports of the progress of shale distillation and ammonia recovery, figures are given compiled from the statistical returns to the Home Office on mines and quarries for the last 10 years to December 1913, and from returns of sulphate of ammonia manufactured :— Total sulphate Year. Total shale mined and of ammonia recovered from Yield in lb. quarried in Scotland. the shale in paiafiin oil per ton of shale. woiks. Tons. Tons. 1904 .. .... 2,331,885 . 42,486 ... ... 40-8 1905 .. 46,344 ... ... 416 1906 .. .... 2.545,724 . 48,534 ... ... 42’7 1907 .. .... 2,690,028 . 51*338 1908 .. .... 2,892,039 . 53.628 .. ... 41*5 1909 .. .... 2.967,017 . 57,048 ... ... 43’1 1910 .. .... 3,130,280 . 59.113 ... ... 423 1911 .. .... 3,116,803 . 60,765 ... ... 43’7 1912 .. .... 3,184,826 . 62,207 ... 43’7 1913 .. .... 3,280,143 . 63.061 ... ... 43T The above ratio is affected by various factors, one of which is that some of the shale mined is used elsewhere than in shale oil works. The ratio is therefore not strictly accurate as to the recovery of ammonia per ton of shale distilled in oil works, but it is approximately so, and the figures for the different years are compar- able. The limited fluctuations in the figures of the fourth column show that little improvement is practicable over the results of recent years.