Briquetting partial

Segments. Segments for heavy-duty use such as for medium-sized tmcks ate produced by a dry-mix process. The fiber, modifiers, and a dry novolak resin are mixed in an appropriate mixer. The blend is then formed into about a 60 by 90 cm preform (or briquet) at 3—4 MPa (400—600 psi). The briquets are hot-pressed for 3—10 min at 140—160°C and then cooled. The resin is only partially cured at this point to be thermoplastic when subsequently reheated for bending. The hot-pressed preforms are then cut to desired size and bent at 170—190°C and cured in curved molds for 4—8 h at 220—280°C. Final grinding produces the finished segments. 

NH4)2S03 sublimes unaltered [946] but the monohydrate undergoes partial decomposition to H20, NH3 and (NH4)2S207. Decomposition of ammonium thiosulphate is inhibited by the addition of other ammonium salts, e.g. (NH4)2C03, and by briquetting [947]. 

Company B Blending ratio DPC 2 and 5% FPC 5% selective blending to partial briquetting of coal charge is also applied. 1. Blending limit is 3-5% partial briquetting of coal charge 2. DPC is superior to FPC. 

Figure 405. Partially assembled modern roller press for coal briquetting with two pocketed rings per shaft. (Courtesy of Koppern, Hattingen, FRG)...

Partial briquetting of coke oven charges The essential difference between the partial briquetting of coke oven charges and the formed coke processes is the densification of only part of the coke oven feed by briquetting. The briquettes are subsequently mixed with loose coal and charged into conventional (slot-type) coke ovens (Figure 410). 

Figure 410. Block diagram of partial briquetting technologies for coke making ...

J. T. Price, J. F. Gransden, and W. R. Leeder, Canadian R D studies of partially briquetted coke oven charges , CANMET Report 82-8E, 1981. 

Fig. 8.88 Partial view of a row of twin (two channel) ram extrusion presses in a lignite briquetting plant (courtesy KRUPP Fordertechnik, Essen, Germany).

From its invention in 1857 to approx, the 1960s, the Exter press was almost exclusively applied for the binderless briquetting of processed (partially dried) peat and soft coal (mostly lignites). For several reasons, during the second part of the 20th century use of such briquettes became no longer acceptable and many of the classic manufacturers of ram presses, who were mostly located in Europe, folded or gave up... 

To obtain the required density, according to IMO the temperature of the feed must be > 650 °C (better > 700 °C). Therefore, all parts of the system that come in contact with the hot material, especially the roller presses and separators must be made of temperature-resistant steel, vigorously cooled, and, at least partially inert (Section 13.3, refs. 102, 125). Fig. 6.9-13 shows views into the hot briquetting bays of different merchant DR plants, depicting the specialized roller presses, and Fig. 6.9-14 shows photographs the facilities. 

Fig. 6.10-9 Partial view of the briquetting bay showing the drive side of the ram extrusion presses [6.10.2.2]...

Fig. 6.10-21 Sketch (partially cut, interior view right ofthe center line) of a vertical pug mill for steam conditioning mixtures offlne coal before briquetting [Section 13.3, ref. Ill]...

Although a number of processes were developed, which were based on the partial removal of volatile matter and/or either cold cure binders or hot briquetting, the meanwhile abundant availability of cheap, clean energy did not let this technology grow as was originally anticipated. The few plants built, mostly in the UK and Japan, were small and used low-capacity roller presses for briquetting. Most of these enterprises became quickly unprofitable and dosed. 

While some of the processes combined known technologies, for example hard coal briquetting with pitch binder and conventional coke making in indirectly heated slot type ovens, others used a number of novel partial steps which, for the complex overall... 

Parallel to the efforts to develop a process in which formed coke is produced as a new commodity, the partial briquetting of coke oven charges was introduced (Fig. 6.10-31). 

Fig. 6.10-32 Mixture of briquettes and loose coal on its way to the coke ovens in one of the plants for partial briquetting (courtesy Iscor, New Castle Works, South Africa)...

Fig. 6.10-10 Partial view of the briquetting building showing the briquetter heads and the beginning of the cooling channels...

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