Green Pellets

Fig. 6. QSL furnace. The green pellets consist of concentrate, fluxes, flue dust, and coal.

A hydraulic setting cement is incorporated as the binder additive. The green pellets are partially hardened in silos, where they remain for about 24-36 hr, and the hardening process is completed during storage in stockpiles. 

Sastry, K. V. S., Similarity size distribution of agglomerates during their growth by coalescence in granulation or green pelletization, Int. J. Miner. Process. 2, 187 (1975). 

In the FASTMET process iron oxide fines (minus 0.1 mm), pulverized coal, and binder are mixed together and pelletized. The green pellets are heated in a dryer to remove moisture and fed to a rotary hearth furnace, where the pellets are placed on a flat rotating surface (hearth) in an even layer one to two pellets deep. As the hearth rotates the pellets are heated to 1250—1350°C, and the iron oxide is reduced to metallic iron in 6 to 10 minutes. 

J.S. Wakeman, Method for evaluation of data from the batch testing of green pellets, Trans. Amer. Inst. Mining Eng., 252 (1972) 83—86. 

Sastry K, Fuerstenau DW. Mechanisms of agglomerate growth in green pelletization. Powder Technol 1973 7 97-105. 

The granulated mixtures are compacted in double-acting, cam-operated automatic pellet presses. The ends of the green pellets are dished by means of punches with slightly convex faces. The dished configuration provides space for thermal expansion of the pellet... 

As in green agglomerate , green pellets , etc., means fresh (e.g. wet), uncured, etc. 

Figure 124. Relationship between percentage of fines in the raw materials and compressive strength of green pellets according to von Struve as well as Urich and Han ...

Cylindrical compacts (approximately 16 mm in diameter and 25 mm long) were formed in a stainless steel die with double- acting rams so that diamond powder was dispersed in the 1/3, 1/5, 1/8 bottom layer of the compacts. In case of the graded dispersion, the composition of each layer was mixed individually, then layered in the steel die in the green pellet. The compacts were pressed uniaxially at the pressure of... 

Fig. 7.20 Sketch of the flow sheet of a drum agglomerator that operates in closed circuit prior to curing the green pellets.

As shown in Fig. 6.8-14, the traveling grate is now completely enclosed and the housing is subdivided to produce the different process conditions. The belt consists of pallet cars with grate bottoms and side walls, connected with each other by hinges to form a continuous unit (Fig. 6.8-15a). To protect the pallet walls, recirculating fired pellets are deposited in the hearth and side layers in which the green pellet bed rests [B.18]. 

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