Materials handling systems, concentrate

Deconstructing value/supply chains, 43 DE (design eflSciency), 369 Dedicated material-handling systems, 1660 Dedicated storage, 2092 DEDS, see Discrete event dynamic system Deep-lane warehousing systems, 2089 Defect concentration diagram (SPC), 1860, 1861... 

Features common to all CVD reactors include source evaporators with an associated gas handling system to control input gases and gas-phase precursor concentrations, a reactor cell with a susceptor heated by either radio frequency or infrared radiation, and an exhaust system to remove waste products (which may include a vacuum pump for low-pressure operations). Substrate temperatures can vary from less than 200 °C to temperatures in excess of 1000 °C, depending on the nature of the material layer and precursor used. Schematic diagrams of some simple CVD reactors are shown in Figure 4. 

The analogue to one-component thermodynamics applies to the nature of the variables. So Ay S, U and V are all extensive variables, i.e. they depend on the size of the system. The intensive variables are n and T -these are local properties independent of the mass of the material. The relationship between the osmotic pressure and the rate of change of Helmholtz free energy with volume is an important one. The volume of the system, while a useful quantity, is not the usual manner in which colloidal systems are handled. The concentration or volume fraction is usually used ... 

The materials handled in the bins were 20% solids by weight, flow of 2.9 tons of water per hour and 47 gallons/minute of pulp. The size of the material was 100 to plus 325 BSS mesh. Maximum acid concentration was 20% hydrochloric acid. The temperature in the system was 60°C. A 6 mm thick natural rubber lining of shore hardness 50°A was used to protect the equipment against the abrasive environment as well as the corrosion effects of hydrochloric acid. 

The handling of incoming concentrates, their storage, blending with flux materials and feeding to the sinter plant requires the use of mobile equipment, feed bins and conveyor systems. Electric power used is around 5 kWh/t of materials handled or 12 kWh/t of product lead. Fuels used for mobile equipment represents 75 MJ/t of material handled or 180 MJ/t of product lead. 

While operators are not required to be proficient in use of the Appendix B tables referred to above, we will cover in class discussions and handout problems to the extent that you will become familiar with the content and application of the tables. Note that releases to the sanitary sewer system are governed by University radiation safety regulations and specific UWNR procedures as well as by 10 CFR Part 20.2003. Releases to the environment for both air and water are covered by lOCFR 20.2001-20.2006, Appendix B, effluent concentration, Columns 1 and 2, and by specific UWNR procedures (to be covered later). The notes at the end of Appendix B indicate how to handle mixtures of radionuclides and situations in which all of the radionuclides in the effluent are not identified. For most materials, maximum permissible concentrations in air and water are dependent upon whether or not the material is water-soluble. For inert gases, such as Ar-41 the limit has the notation "Sub", which means the concentration limit is based on external radiation to the whole body from submersion in an infinite cloud of gas at that concentration, not on accumulation of a body burden or dose to a critical organ. 

Most of the systems that have been installed concentrate on the materials handling as much as on control of the mixing process itself. Early systems were controlled using punched cards which gave instructions on weighing and addition of raw materials and on dump criteria. Basically, these systems reduced the chance of human error. More recent systems do all of the above, but also include a programmable controller. One important advantage of these is that they can provide a printed record of each batch. Details of the... 

The pneumatic classification system should be designed to handle ha2ardous dust (28). A ha2ardous dust is one which, when finely divided and suspended in air in the proper concentration, bums, produces violent explosions, or is sufficiently toxic to be injurious to personnel health (see Air pollution control methods Powders, handling). At the least, almost any dust can be irritating to personnel because of inhalation or skin or eye contact. Fully oxidi2ed and hydrated materials are generally considered safe. 

Concentration Control. Sequestration, solubilization, and buffering depend on the concentration control feature of chelation. Traces of metal ions are almost universally present in Hquid systems, often arising from the materials of the handling equipment if not introduced by the process materials. Despite very low concentrations, some trace metals produce undesirable effects such as coloration or instabiHty. 

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