Flotation Assistance

Two methods of flotation assistance in the open sea are usually provided for the number of personnel on board (POB) the installation. They may consist of the following. 

A prime consideration in the provision of lifeboats for offshore installations is that they can be readily maneuvered away from the structure of the installation. Recent trends have been for the orientation of lifeboats to point outwards so that egress away from the structure is improved and the fear of being swept into the platform by the waves and current is lessened. Positioning in an outward orientation also improves the evacuation time for the boat to get away from the incident. 

American Society of Testing Materials (ASTM), F 1166. Standard Practice for Human Engineering Design for Marine Systems. Equipment and Facilities. ASTM, Philadelphia, PA, 1988. 

Acoustical Society of America (ASA), S3.41. Audible Emergency Evacuation Signal. (ASA 96), ASA, New York, NY, 1990. 

British Standards Institute (BSI), BS 5395 Part 3 1985. Stairs ladders and walkways. Part 3 Code of Practice for the design of industrial type stairs, permanent ladders and walkways, BSI, London, UK. 1985 

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When separating low-density solid particles or oil droplets from water, the most common method used is dissolved-air flotation. A typical arrangement is shown in Figure 8.12b. This shows some of the effluent water from the unit being recycled, and air being dissolved in the recycle under pressure. The pressure of the recycle is then reduced, releasing the air from solution as a mist of fine bubbles. This is then mixed with the incoming feed that enters the cell. Low-density material floats to the surface with the assistance of the air bubbles and is removed. 

The chemicals added to the flotation cell assist in separating the ink from the fiber and enhance the ability of the ink particles to adhere to the bubble surface. A common chemical added to the cell is sodium hydroxide (NaOH) which causes the fiber to swell, thus releasing the ink particle... 

Finkelstein, N. P., 1999. Addendum to The activation of sulphide minerals for flotation a review. Inter. J. Miner. Process, 55(4) 283 - 286 Fomasiero, D., Montalti, M., Ralston, J., 1995. Kinetics of adsorption of ethyl xanthate on pyrrhotite in situ UV and infiared spectroscopic studies. Langmuir, 11 467 - 478 Forssberg, K. S. E., Antti, B. M., Palsson, B., 1984. Computer-assisted calculations of thermodynamic equilibria in the chalcopyrite-ethyl xanthate system. In M. J. Jones and R. Oblatt (eds.). Reagents in the Minerals Industry. IMM, Rome, Italy, 251 - 264 Fuerstenau, M. C., Kuhn, M. C., Elgillani, D. A., 1968. The role of dixanthogen in xaomthate flotation ofpyrite. Trans. AIME, 241 437 Fuerstenau, M. C. and Sabacky, B. J., 1981. Inter. J. Miner. Process, 8 79 - 84 Fuerstenau, M. C., Misra, M., Palmer, B. R., Xanthate adsorption on selected sulphides in the presence of oxygen. Inter. J. Miner. Process... 

Thanks are due to Miss. U. Wamsler from this department for her technical assistance with the flotation measurements. 

Bitumen is recovered using a caustic assisted hot water flotation process and diluted with naphtha to facilitate the removal of residual solids and water. Diluent naphtha is removed by distillation prior to feeding bitumen to the Upgrading facilities. 

ACTIVATOR. 1. A substance that renders a material or a system reactive commonly, a catalyst. 2. A special use of this term occurs in the flotation process, where an activator assists the action of the collector. 3. An impurity atom, present in a solid, that makes possible the effects of luminescence, or markedly increases their efficiency. Examples are copper in zinc sulfide, and thallium in potassium chloride. See also Enzyme. 

The role of turbulence in assisting with suspension stability is described in Section 10.3.1. For example, a rule of thumb for the role of turbulence in maintaining sufficient suspension stability for mineral flotation is the one-second criterion which states that the particles in a suspension are sufficiently well dispersed for flo-... 

Foams and emulsions may also be encountered simultaneously [114]. Figure 1.5 shows an example of an aqueous foam with oil droplets residing in its Plateau borders (see Section 5.6.7). In addition to containing gas, an aqueous phase, and an oleic phase, foams can also contain dispersed solid particles. Oil-assisted flotation of mineral particles provides one example (Chapter 10). Oil-sand flotation of bitumen provides another (Chapter 11). In the case of oil-sands flotation, an emulsion of oil dispersed in water is created and then further separated by a flotation process, the products of which are bituminous froths that may be either air (and water) dispersed in oil (from primary flotation) or air (and oil) dispersed in water (from secondary flotation). In either case, the froths must be broken and de-aerated before the bitumen can be upgraded to synthetic crude oil. (See Section 11.3.2). 

Conventional filtration methods for separation generally use physioal devices such as membranes, sieves or filtration beds and force-driven methods suoh as settling, flotation or centrifugation. Some invoive the assistance of external (eleotrio or magnetic) fields. 

Use Synthesis of rubber accelerators and age resisters, perfumery, engraving, ore flotation, solvent, solvent mixtures for cellulose acetate, fungicides, organic synthesis, printer s rollers, cadmium plating, dyes, drugs, dyeing assistant, synthetic polymers. 

Use Synthesis of pharmaceuticals, dyestuffs, rubber chemicals, flotation agents, insecticides, fungicides, plasticizers, textile assistants, herbicides, oil additives, rust preventives, and pickling inhibitors. 

If a bubble carrying air-avid mineral particles reaches the surface of the flotation unit and then bursts, the raised mineral particles will sink again. Bubble stability is maximized by addition of a foam stabilizer or frother, which assists in generating a sufficiently stable foam layer on the flotation unit to enable the foam plus associated mineral to be skimmed from the water phase. The frother also puts an oily phase on the surface of each bubble as it forms, which helps the mineral-gangue differentiation function of the collector. Typical frothers are oily materials of no more than slight water solubility such as pine oil (a mixture of terpenes) or a long chain (C5 or higher) alcohol such as 1-pentanol, and are used at the rate of 20-45 g/tonne of ore. 

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