THE COLLIERY GUARDIAN AND JOURNAL OF THE COAL AND IRON TRADES. Vol. CIX. FRIDAY, JUNE 4, 1915. No. 2840. Recent Developments in Coal Briquetting.* By CHARLES T. MALCOLMSON. A description is given of the Rutledge press, which has been developed to meet American conditions. A prominent feature is the use of a “fluxor” of special construction, utilising superheated steam. The press is of the continuous type, consisting of a chain of moulds oi die-plates passing under a feeding hopper and between t m revolving drums, upon which punch rams are carried. In the United States, improvements in methods of combustion have made possible the use of the smaller sizes of anthracite. This coal is now being reclaimed. Fig. 1.—Berwind Briquetting Plant, Superior> Wisconsin. ’■’’Wl® 1 >"■“1 sjl ■ —I from the culm banks accumulated by the miners in the more prodigal years. To-day, the freshly mined “ slush ” is segregated and stored against the time when, through briquetting or some other means, it may be utilised as a commercial fuel. The experience of the past few years- points to the conclusion that the anthracite product as now manu- factured is not what the consumer wants. Briquettes marketed on the Eastern seaboard are nearly all made with coal-tar pitch as a binder, following the European practice, and are sold for domestic purposes at from 1 dol. to 1-50 dol. below the price of chestnut coal. While the culm may not contain more ash than is allowed by the Government specification for prepared sizes of anthracite, the ash is thoroughly distributed through the briquette, and this feature, combined with conditions under which the fuel is consumed, causes the binder to distil off ’at lower temperatures than the coal burns, thus producing some soot and smoke. While this defect is not great, the difference in price does not seem to compensate for it. Other binders which will eliminate this objectionable feature are now available. The greatest single impetus to the industry was given by the United States Geological Survey through its experiments at St. Louis and Norfolk, from 1904 to 1907. During this period the Semet-Solvay Company erected a plant at Detroit to utilise its accumulations of coke breeze. Results at this plant demonstrated the necessity of equipment designed to meet American conditions. It must be borne in mind that the most important commercial feature in the marketing of briquettes is the margin between the ‘Selling price of the fine coal to be briquetted and that of the prepared coal which the briquettes meet in competition. It is principally because of the variableness of this margin that the coal- briquetting industry has not been successful in every part of the United States where it has been tried. In 1909, the Standard Briquette Fuel Company built a plant at Kansas City, Mo., to try out a 10-ton per hour plunger press, following the German and English * From a paper read before the American Institute of Mining Engineers. design, but modified to meet American conditions as to size of briquettes. The plant was an improvement over former designs, but after two years of costly experimentation the press was replaced by another of the same tonnage. Even after the second press was perfected mechanically, during a period of two years, its operating cost was too great to make briquetting pro- fitable on the margin obtaining at Kansas City. About this time a plant of somewhat similar design, and using a Renfrow press, was built by the Detroit Coalette Fuel Company. It is still in operation, producing 12-oz. briquettes out of Pocahontas ceal at the rate of 8 tons per hour. The same necessity for conservation which found a use for the hitherto waste coal in the culm banks of Eastern Pennsylvania, found a market for the fine coal in the great Mississippi Valley region. This market was created by the development of the mechanical stoker, and as a result the prices of slack and lump coal were more nearly equalised. Hence it transpired that the future of bituminous briquettes must be limited to domestic use, and that the industry could be made profitable only by developing highly efficient machinery of large tonnage. The railroads and large coal operators Fig. 2.—Rutledge Briquetting Press and Fluxor. could. be interested only on this basis. The Rutledge: press was designed to meet these conditions. The St. Louis Briquette Machine Company began in 1909 the construction of a plant at Livingston, HL, to be used in perfecting the Rutledge press, and to learn something of the value of Illinois briquettes. The plant had a capacity of 32 tons per hour of 16-oz. briquettes. In 1911, the press had been sufficiently developed to warrant the Berwind Fuel Company in contracting for the construction of a plant on its dock at Superior, Wis., which was completed the following year. Within a year after the operations were begun, a second complete unit was installed, bringing the rated capacity of this plant up to 80 tons of 13-oz. briquettes per hour, and making it by far the largest plant in the country. Thus the briquetting industry at the head of the Lakes was from the outset placed on. a sound economic basis. Before passing to a description of the plant which forms .the basis of this paper, it will not be amiss to mention the Stott Briquette Company’s plant at Superior, Wis., built in 1910. After several unsuc- cessful attempts to exploit anthracite briquettes, the company decided this year to manufacture a product consisting principally of Pocahontas coal. A modified Belgian roll press, built by the Mashek Engineering Company, is used, producing 2-oz. . pillow-shaped briquettes at the rate of 12 tons per hour. The residue from petroleum is used as a binder. In all coal-briquetting the binder is a factor of prime importance. Coal-tar pitch has been generally recog- nised in Europe as the logical binder for coal briquettes. It has one serious defect : it will not make a smokeless fuel out of anthracite culm. To remedy this evil, binders of vegetable origin have been much exploited. They are, however, expensive, difficult to handle, and do not make waterproof briquettes., Two small plants in the country are using vegetable binders, of which starch is the principal ingredient, and one plant uses oil emulsified with starch. In all cases the briquettes must be baked before shipment, and the product is irregular in quality. The processes can hardly be said to be commercially successful. Another excellent binder is asphalt obtained from the distillation of petroleum. It has many of the qualities of coal-tar pitch; the diffi- culties in its use will be referred to later. The coal-briquetting plant of the Pacific Coast Coal Company is located near Seattle, Wash., close to the shore at the southern end of Lake Washington. It is served by the Newcastle branch of the Columbia and Puget Sound Railroad, from which a spur passes the plant on its way to the coal piers at this end of the lake. The raw coal is delivered to the plant in dump-bottom cars, and is unloaded through a track hopper alongside the raw coal bin. A gravity-discharge elevator, into which the coal is delivered from the track hopper by a reciprocating feeder, elevates the coal to an 800-ton raw coal storage bin, of wooden construction and divided into two compartments. Two feeders deliver the coal from these compartments into two flight con- veyors. These feeders are designed for close regulation, so that the requirements of the plant can be adjusted at this point. The feeders are driven through friction clutches by an electric motor. The raw coal Conveyors, travel horizontally and terminate at the intake chutes of the driers. Between the driers and the raw coal bin a Williams dustless crusher is installed. Gates and chutes, permit the delivery of coal from either raw coal conveyor to the crusher, from which it is discharged into a continuous-bucket elevator, and is again elevated to the raw coal conveyors. If the coal is very wet, it may be passed directly through either drier to a flight conveyor installed between the driers, which returns it to the crusher. The necessary part of the surface Fig. 3.—Cooling Conveyor. I moisture is eliminated in the first drier, and after crushing the coal is completely dried and heated in the second drier. This duplicate. arrangement of driers and conveying machinery permits the blending of two or more coals, to improve the quality of the mixture, and ensures uniformity of the dried product. Two Ruggles-Coles A-14 driers of improved design, with shell of special length, are installed in the drier building. Each of these driers is direct-driven by an electric motor of sufficient size to pick up the load under all conditions. The exhaust fans are driven by variable-speed motors through silent-chain drives, and the exhaust gases pass through cyclone separators