Grain size fractions

The plant is used to produce two chemically different EPS -types A and B in five grain size fractions each from raw materials FI, F2, F3. The polymerization reactions exhibit a selectivity of less than 100% with respect to the grain size fractions Besides one main fraction, they yield significant amounts of the other four fractions as by-products. The production processes are defined by recipes which specify the EPS-type (A or B) and the grain size distribution. For each EPS-type, five recipes are available with the grain size distributions shown in Figure 7.2 (bottom). The recipes exhibit the same structure as shown in Figure 7.2 (top) in state-task-network-representation (states in circles, tasks in squares). They differ in the parameters, e.g., the amounts of raw materials, and in the temperature profiles of the polymerization reactions. 

The scheduling problem is complicated by the fact that the coupled production of grain size fractions and the mixing in the finishing lines prohibit a fixed assignment of recipes to products. Furthermore, there is neither a fixed assignment of storage tanks nor of polymerization reactors to batch processes. 

The plant is used to produce type A and type B of the polymer expandable polystyrene (EPS) in F = 5 grain size fractions each from a number of raw materials ( ). The availability of raw materials and the product storage capacity are assumed to be unlimited. The preparation stage is not limiting the production process... 

Fig. 1. Log-ratio-based normalization trends for Gulf of Trieste sediments. Grain-size fractions measured in %, chemical components scaled to relative abundance.

Thode HG, Rees CE (1976) Sulphur isotopes in grain size fractions of lunar soils, Proc Lunar Sci Conf 7 459-468... 

Table 10. Weight percent of ash panicles in different grain-size fractions bused on dry sieving at different locations in the boiler at Eesti power plant (locations 1-9 indicated in Fig. 6) ...

The continental slope represents a transit zone of the sediment fluxes supplied in the form of detrital matter from the rivers and the products of abrasion, as well as the sediments carried by turbidity flows. The continental slope is covered with compacted clayey oozes (grain-size fractions of 0.001-0.01 mm). At selected places on steeper parts of the slope, remains of mollusk fauna such as shells of Dreissena rostriformis have been encountered. At sites with gentle sloping, they are overlain by the Holocene and recent sediments [11]. 

Carbon refractories. Carbon blocks used in the construction of blast-furnace hearths are made from dense coke possibly mixed with anthracite. Suitable grain-size fractions (up to 5—15 mm) are mixed with tar to a plastic mass which is shaped at elevated temperature by pressing or ramming. The products are fired without air at about 1400 °C in saggers covered with fine-grained coke. The carbonized tar produces a firm bond between the grains. Granular mixes arc also used in certain applications. 

Figure 6.3. Percentage of grain size (fraction < 62 pm) in transects 1 and 2.

Trace metal analysis of a specific grain size fraction of sediment < 64 pm (sieving) < 20 pm (sieving) < 2 pm (settling tube) O Reilly Wiese, Bubb Lester (1995) Ackermann, Bergmann Schleichert (1983) Banat, Forstner Muller (1972)... 

Table 3.3 gives the calcium CECs for the six California oil sands at ambient temperatnre (Somerton and Radke, 1983). Also shown are the weight percentages of montmoriUonite in these sands. These data are obtained for the grain size fraction < 43 pm. Note that the exchange capacities generally parallel the montmoriUonite contents of the sands. 

Data on total organic carbon (TOC) and grain size fractions as presented in Tab. 1 were also provided by the German Federal Maritime and Hydrographic Agency (Hamburg). 

On the other hand, it has been argued by Ackermann (1980) that separation of fraction <20 p.m, which can also be performed with nylon sieves should be favoured at least for coastal sediments, where the correlation with conservative elements has been found to be better with this fraction than with fraction <63 (im (see below). Also for organic pollu tants, separation of fraction <20 um seem to compare favourably with other grain size fractions (Hellmann, 1983). 

Suitability of reference elements have been tested by Ackermann (1980) on sediment samples from the Ems River estuary in Northern Germany. Table 3-3 summarizes the correlation coefficient "r between the contents of conservative elements and the percentage of grain size fraction <20 um and <63 um, respectively, and the slope of the regression line, the quotient s(100%)/s(0%) from the ordinate values extrapolated... 

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