Solid/liquid separation laboratory tests

Plastics are frequently used for applications requiring erosion resistance, but there does not seem to be much activity or interest in the tribology community of the 1990s. However, there are a number of tests that are applied and have been used to rate erosion resistance of plastics. Erosion, by definition, is progressive loss of material fiom a solid surface due to mechanical interaction between that surfitce and a fluid, a multicomponent fluid, or impinging liquid or solid particles (3). The field of erosion is usually separated into a number of forms of erosion liquid erosion, either continuous stream or droplet, solid particle erosion, slurry erosion, and cavitation erosion. Each have separate laboratory tests. 

Note that filter aid selection must be based on planned laboratory tests. Guidelines for selection may only be applied in the broadest sense, since there is almost an infinite number of combinations of filter media, filter aids, and suspensions that will produce varying degrees of separation. The hydrodynamics of any filtration process are highly complex filtration is essentially a multiphase system in which interaction takes place between solids from the suspension, filter aid, and filter medium, and a liquid phase. Experiments are mandatory in most operations not only in proper filter aid selection but in defining the method of application. Some general guidelines can be applied to such studies the filter aid must have the minimum hydraulic resistance and provide the desired rate of separation an insufficient amount of filter aid leads to a reduction in filtrate quality — excess amounts result in losses is filtration rate and it is necessary to account for the method of application and characteristics of filter aids. 

Level 1 sampling provides a single set of samples acquired to represent the average composition of each stream. This sample set is separated, either in the field or in the laboratory, into solid, liquid, and gas-phase components. Each fraction is evaluated with survey techniques which define its basic physical, chemical, and biological characteristics. The survey methods selected are compatible with a very broad spectrum of materials and have sufficient sensitivity to ensure a high probability of detecting environmental problems. Analytical techniques and instrumentation have been kept as simple as possible in order to provide an effective level of information at minimum cost. Each individual piece of data developed adds a relevant point to the overall evaluation. Conversely, since the information from a given analysis is limited, all the tests must be performed to provide a valid assessment of the sample. 

Laboratory experiments may also be necessary to aid in the selection and preliminary design of separation operations. The separation of gas mixtures requires consideration of absorption, adsorption, and gas permeation, all of which may require the search for an adequate absorbent, adsorbent, and membrane material, respectively. When nonideal liquid mixtures are to be separated, laboratory distillation experiments should be conducted early because the possibility of azeotrope formation can greatly complicate the selection of adequate separation equipment, which may involve the testing of one or more solvents or entrainers. When solids are involved, early laboratory tests of such operations as crystallization, filtration, and drying are essential. 

Purchas (1981) has suggested a selection system consisting of three selection steps to produce a shorthand profile of the application from a combination of desk study to define the required duty, and some simple laboratory testing to characterize the separation properties of the solid-liquid mixture. The profile is expressed as a sort of code formed from a group of alphabetic letters (e.g., bdh-BEG-K), and is used in a fourth step to select suitable... 

The manufacturer requires complete solids and/or liquids data, feed size analysis, and requirements for separation. In some instances, it may be best to have a sample tested by the manufacturer in their laboratory. 

Trimedlure may exist in eight different isomeric forms, depending on which of the four dotted lines of Figure 3 the chlorine atom resides upon, and whether the methyl and ester groups are cis or trans. Our preparations of trimedlure are not pure compounds but mixtures of isomers. Trimedlure has been separated into two solid isomers and a liquid fraction. Tests at our Hawaii laboratory indicated that one of the solids and the liquid portion of trimedlure are attractive, but the other solid is not attractive 91). Apparently, stereoisomerism can play an important role in insect attraction. 

---