Capital cost pellet

Other apphcations include dewatering extremely fine (0.1 llm) laterite leach tailings (91). These pelletizing processes should be compared in flocculant consumption and operating and capital costs with belt-filter presses. 

Base Metal Catalyst - An alternate to a noble metal catalyst is a base metal catalyst. A base metal catalyst can be deposited on a monolithic substrate or is available as a pellet. These pellets are normally extruded and hence are 100% catalyst rather than deposition on a substrate. A benefit of base metal extruded catalyst is that if any poisons are present in the process stream, a deposition of the poisons on the surface of the catalyst occurs. Depending on the type of contaminant, it can frequently be washed away with water. When it is washed, abraded, or atritted, the outer surface is removed and subsequently a new catalyst surface is exposed. Hence, the catalyst can be regenerated. Noble metal catalyst can also be regenerated but the process is more expensive. A noble metal catalyst, depending on the operation, will typically last 30,000 hours. As a rule of thumb, a single shift operation of 40 hours a week, 50 weeks a year results in a total of 2,000 hours per year. Hence, the catalyst might have a 15 year life expectancy. From a cost factor, a typical rule of thumb is that a catalyst might be 10%-15% of the overall capital cost of the equipment. 

In a typical 80,000 tons/year plant, capital costs were about 220 per metric ton in 1974. To produce 1000 kg of polymer, 1030 kg of monomer is needed, together with 1 kg of hydrogen and 25 kg of diluent. Catalyst and miscellaneous chemicals cost about 4 per 1000 kg of polyethylene pellets produced. For production, 300 kg of medium-pressure steam, 800 kg of low-pressure steam, 530 kWh of electrical energy, 200 m3 of water, 30 m3 of nitrogen, and 600 m3 of air are also required. To polymerize propylene in suspension, the same technology can be used. Catalysts now available [based on TiCl3 (see Table II)] make it unnecessary to separate isotactic from atactic materials. 

Capital costs and overhead vary among producers, and include expected return on investment. Fuel and power vary geographically. Labor and maintenance are significant processing cost factors as shown in the rough cost array that is a result of our experience with cubing and pelleting systems for various residues. 

Gudmundsson and Borrehaug have presented results from a study to determine the feasibility of transporting natural gas in the frozen hydrate form. A NGH transportation chain comprises hydrate production, marine transport, and regasification elements. Even after a conservative economic analysis, it was found that the capital cost associated with an NGH chain will be 28% lower than the equivalent LNG chain. Takaoki et al. found that the most suitable way to store hydrate for transportation was as small pellets. 

Steam-fluidized beds with steam have been in successful operation in South Africa for nearly a decade (Faber et al., 1986). Faber et al. (1986) have shown that fluid-bed steam drying of activated carbon pellets saves energy (15%) as well as capital costs (14). 

This is a process where a split, hollow mould is supplied either with a PVC plastisol or some other plastics in powdered form. The mould is then rotated on two axes at right angles to each other and heated so that the thermoplastic flows and covers the inner surface of the mould. Tooling costs are, therefore, low because no great pressures are involved. Mild steel sheeting or cast aluminium moulds are usually used. Equipment capital costs are also reasonably low. Raw material costs are higher than for some other processes because the powders used have normally to be obtained by grinding pellets, while plastisols also have to be specially compounded. 

Power consumption, equipment geometry, wear rate, as well as capital and operating costs, are all directly correlated to the internal working pressure. Therefore, there are good reasons to consider lower extrusion pressures obtained in peripheral or radial extruders and pelleting machines. 

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