FROM RAW MATERIAL TO FINAL PRODUCT

You might ask yourself Why is one substance a ceramic, another a polymer and a third a metal This paragraph will answer this question by demonstrating that the individual forming processes (syntheses) are subject to certain rules and the nature of the product of the synthesis can be predicted to a large extent. 

During a synthesis the basic substances or reagents are mixed and consequently react under specific reaction circumstances to form products with usually totally different properties. With reaction circumstances we might mean high temperature or pressure, irradiation with ultraviolet light, the presence of a catalyst and many other possibilities. 

A reaction is called exothermic when it is possible to remove the energy of activation after some time because the reaction proceeds with the help of the energy produced in the reaction. A good example of this is the so-called volcano test some ammonium dichromate is shaped into a small volcano crater. A bright flame is held to the crater until the reaction starts the volcano produces a green powder, chromium(III) oxide  

Among other things, the nature of the new bonds, and consequently the products, is determined by the energy balance. That is to say, each reaction aspires to use as little energy as possible in the formation of the main product in the case of an endothermic reaction and to produce as much energy as possible in the case of an exothermic 

When a product is a solid which can occur in several crystal structures (polymorphology), the reaction circumstances determine which structure will be formed. And thus some more factors can be mentioned which determine the nature of the product. A chemist is able to select these circumstances quite accurately and thus ensure an optimal yield of the desired substance in the synthesis. Afterwards it is very often necessary to purify the product, which often requires much more time than the synthesis itself. 

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Any process which is a consequence of discrete tasks that have to follow a predefined sequence from raw materials to final products is a batch process. This predefined sequence is commonly known as a recipe. The primary features of any comprehensive recipe are the quantities of materials that have to be processed by individual tasks as well as the duration of each task within the recipe. The secondary features are the operating conditions of the various tasks, and in less common circumstances, the locality or geographic position of the task at hand. In processes wherein safety is of great concern, it might be necessary to perform a particular task in a designated area equipped with relevant safety features. 

Batch chemical processes are broadly categorised into multiproduct and multipurpose batch plants. In multiproduct batch plants, each produced batch follows the same sequence of unit operations from raw materials to final products. However, the... 

What If/Checklist. The most frequently used method of process hazard review, the what if/checklist, is effective in reviews of relatively uncomplicated processes from raw materials to final product. The team formulates and answers What if questions at each handling or processing step to evaluate the effects of component failures or procedural errors. They use a checklist to ensure that all important subjects are addressed. This method should be used as the first step in all process hazard reviews. 

Obviously the future costs given in Table 4-1 are speculative and were based on the committee s consensus views of what might be possible. They are to some extent optimistic. Table 4-1 also includes a column on overall efficiency from raw material to final product at the pump, which is interesting for showing how difficult it is to approach today s gasoline refining and delivery efficiencies. 

In the past decades, nuclear magnetic resonance (NMR) spectroscopy has been used extensively to study various aspects of polymer chemistry and engineering. Fig. 1 shows the relationship among polymerization conditions, polymer structure, and the material s physical structure and end uses. Solution, solid state, and imaging NMR techniques contribute to imderstanding the physical and chemical aspects of the route from raw materials to final product. Solution NMR provides information about all aspects of the polymerization reactions and the final structure of the synthesized polymer. This information can be correlated with the material s final properties and provide feedback to control the initial polymerization process so that the fraction of structures responsible for desirable properties can be controlled in a systematic way. 

Short-path process from raw material to final product... 

The production of high-value-added products (pharmaceutical active principles, agrochemicals, etc.) has stimulated investigations on batch processes for several decades. Generally, a batch plant can manufacture several products sharing standard equipment in a series of production campaigns, with the ability to adapt itself to variations of raw materials and to rapid market flucmations. A batch process involves discrete tasks embedded in an interconnected predefined sequence from raw materials to final products. The predefined sequence is commonly known as a recipe. The recipe consists of the amount of raw materials that are necessary to be involved in the individual tasks as well as their durations. It also includes the operating conditions of the tasks as well as additional constraints of the process (safety features for instance). 

Golhar and Sarker (1992) and Jamal and Sarker (1993) consider the basic model under policy (a) with the assumption that the conversion rate from raw material to final product is one to one. Two cases are considered (i) Imperfect matching - production uptime and cycle time are not exact integer multiples of finished product delivery cycle (ii) Perfect matching the above numbers are integers. An iterative heuristic is used to solve the problem. Sarker and Parija (1994) consider exactly the same problem except that the conversion rate from raw material to final product is not assumed to be one to one. An exact algorithm is proposed. 

The production of moldings is the shortest way from raw material to finished product. Forming, including all related activities, is thereby bypassed. A form almost equal to the component s final shape is achieved in only one direct operation, and masses ranging from less than 1 g to hundreds of tons can thus be handled. 

FIGURE 13.1 Alkanolamides pathways from different raw material to final products (TOFA—Tall oil fatty acid). 

Hot and cold methods are also used to create synthetic fibers. A strand of fiber is a single filament that can be combined or spun with other filaments to create the final fiber product. The process from raw polymer to final product is called spinning, as illustrated in Figures 13.39 and 13.40. The cross-sectional shape of the strands is dictated by the shape of the orifice through which is it extruded. As shown in Figure 13.39, extruded fibers are spun together into a filament (bundle of fibers) that can be cut into smaller staple fibers with lengths on the order of centimeters or less that may be further processed into textile materials. ... 

Primary shaping can also be applied to materials that cannot be processed with other manufacturing techniques. An advantageous material and energy balance is ensured by the direct route from raw material to the molding or the final product. 

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