(_a_) _Accretions_, (_b_) _Irregular working of the furnace and the charge_, (_c_) _Clotting and low concentration_, (_d_) _Heavy flue-dust losses_, and their presence is often the cause of much trouble at many of the modern smelters. The agglomerating of the fines is, therefore, a very important preliminary in any scheme of treatment involving the employment of the blast furnace on such material. Agglomerating is usually performed by one of two methods—(1) briquetting, (2) sintering. Of these, briquetting has hitherto been in very general use, but several advantages connected with the sintering process and the resulting product are leading to its adoption with much success in several localities, and attracting for it considerable attention at present. (_a_) =Briquetting=.—Among the advantages of briquetting is the fact that it utilises large quantities of the copper-bearing slime produced at the concentrating plant, this material often possessing good binding properties which render it very suitable for briquette-making. [Illustration: Fig. 13.—Sketch Plan of Briquetting Plant.] [Illustration: Fig. 14.—Section through Auger-Former, showing Briquetting Mechanism, of Chambers’ Machine.] [Illustration: Fig. 15.—Chambers’ Briquette-making Machine.] The type of plant in use at different smelters varies considerably, the method adopted being either the stamping out of the briquettes, or by the application of steady pressure, the production of bars which are then cut up to convenient size. The constituents used depend naturally on the materials available at the smelter, briquettes, both with lime and without, being made. _The Briquetting Plant at Anaconda._—The operation of this plant affords a good example of the process. Its working is very successful in using up much fine concentrate, as well as the slime from the ponds, which acts as binding material and at the same time supplies copper. Briquette, indeed, constitutes one of the biggest items of the charge for the Anaconda blast furnaces. There are four Chambers’ machines in use, making 840 tons of briquettes daily. The briquettes consist of slime, fine first-class ore screenings (< ⅜-inch size), fine concentrate from the dressing plant, and coke (which is recovered from the reverberatory furnace gratings). The quantities used daily are somewhat as follows, though they are naturally subject to some variation, depending on supplies:— Slime, 500 tons. First-class ore screenings, 300 " Fine concentrate, 200 " Coke, 70 " and the composition of the briquettes is about—