Continuous melting

Process Batch-continuous Melt-solution Mode Auxiliary... 

Soda-lime glass accounts for about 90% of the U.S. production. It is produced in large, direct-fired, continuous-melting furnaces in which the... 

Introducing this expression into (9.3.14), the equations for continuous melting become... 

Figure 9.7 The continuous melting model for Dt=0.001 and diverse values of the residual porosity

REACTOR DESIGN FOR CONTINUOUS MELT-PHASE POLYCONDENSATION... 

Additional processes include the Woera and the Irstil processes w hich arc based upon continuous melting and/or relining techniques. The eycloslecl and jet-smelting processes make liquid iron by Hash smelting of iron ore. 

PVC powder compounds are heated, sheared, and deformed during melt processing. During this process, the grains of PVC are broken down. A processing window of stable primary particles exists even with continued melt processing. The primary particle is about a billion molecules of PVC held together by a structure of crystallites and tie molecules. 

Table 3 (continued) Melting Point, °C -AHg (avg)/ Kcal/mole... 

F STC-H T-23-0225-75, US Army Foreign Sci Technol Center, Charlottesville, Va (1974) (Limited distrib) 21) R-G. Hunt T.A. Groce, Hazard Analysis of Continuous Melt-Pour System , Rept A0258-740-03-010, Herc-74-6, Allegheny Ballistics Lab, Hercules, Inc, Cumberland, Md (1974) (Limited distrib)... 

Figure 4.106 Scheme of a continuous melt-coating process of polymer foils 1, powder for coating 2, substrate unwinding 3, preheating ... 

Polyethylene Terephthalate. PET (Table 15.9) is produced by continuous melt condensation polymerization of ethylene glycol plus terephthalic acid,... 

Because direct dynamic measurements of materials state within the barrel are impossible, the structural and molecular changes relevant to extrusion must be measured off-line and related to real process conditions. In principle, we need to explain not only the effect of applied physical parameters of heat, shear and pressure, but also the effect of formulation. This is not yet possible, and for reasons stated above, the behaviour of carbohydrate (starch) dominated systems will be quite different from proteinaceous systems, since their heat denaturation behaviour and glass to rubber transitions are different in detail during their conversion from a moist powder to a continuous melt. ... 

After hydration, a rise in temperature causes disruption of internal structure, for example crystallites in starch or folded structure in proteins. The extent to which this is achieved is determined primarily by a specific cooperative melting event, whose temperature is dependent upon moisture content and applied pressure. If these critical conditions are reached by any part of the flow stream, then shear can cause further fragmentation of both starch granules and the polymers released from them, whereas for proteins or their dissociated subunits, molecular weights remain largely imchanged. A polymer continuous melt is formed in both cases. 

They report no microscopic structures of their extmdates, but from the extrusion conditions reported it is likely that homogeneous starch continuous melts were... 

One other parameter critical to product properties is the size distribution of the bubbles in the expanded product. Comparable bulk densities will be measured either with a few large bubbles or a large number of small ones. However, the rehydration and textural properties of the two structures will be markedly different. The distribution of bubble sizes relates to nucleation rather than growth. Frequently, the presence of insoluble particles in the melt is sufficient to cause multisite nucleation as shown in the above figure, but when this is not the case, small amounts of finely divided powder can be added to the formulation. Calcium carbonate is frequently used, acting as a weak point in the continuous melt, and also releasing gaseous carbon dioxide (personal communication, Charles Chessari, Food Science Australia, N. Ryde, Australia). 

Gurenko A. A. and Chaussidon M. (1995) Enriched and depleted primitive melts included in olivine from Icelandic tholeiites origin by continuous melting of a single mantle column. Geochim. Cosmochim. Acta 59, 2905-2917. 

Figure 23 Chondrite-normalized abundances of REEs in representative harzburgites from the Oman ophiolite (symbols—whole-rock analyses), compared with numerical experiments of partial melting performed with the Plate Model of Vemieres et al. (1997), after Godard et al. (2000) (reproduced by permission of Elsevier from Earth Planet. Set Lett. 2000, 180, 133-148). Top melting without (a) and with (b) melt infiltration. Model (a) simulates continuous melting (Langmuir et al., 1977 Johnson and Dick, 1992), whereas in model (b) the molten peridotites are percolated by a melt of fixed, N-MORB composition. Model (b) is, therefore, comparable to the open-system melting model of Ozawa and Shimizu (1995). The numbers indicate olivine proportions (in percent) in residual peridotites. Bolder lines indicate the REE patterns of the less refractory peridotites. In model (a), the most refractory peridotite (76% olivine) is produced after 21.1% melt extraction. In model (b), the ratio of infiltrated melt to peridotite increases with melting degree, from 0.02 to 0.19. Bottom modification of the calculated REE patterns residual peridotites due to the presence of equilibrium, trapped melt. Models (c) and (d) show the effect of trapped melt on the most refractory peridotites of models (a) and (b), respectively. Bolder lines indicate the composition of residual peridotites without trapped melt. Numbers indicate the proportion of trapped melt (in percent). Model parameters...

---