PELLETISING

Another variation of the string discharge is the use of a thick plastic belt which is perforated by conical openings. The dmm is covered with filter cloth and the belt covers the cloth for the filtration and dewatering operations. The soHds fill the perforations in the belt and then leave the dmm with the belt to be discharged by air blow as pellets. This is an effective way of pelletising coarse mineral ores. 

The Vinyloop process is based on the selective dissolution of PVC used in composites applications like cable insulation, flooring, tarpaulins, blisters, etc. After removal of insoluble parts like metals, rubber or other polymers, the PVC is reprecipitated with all additives by introduction of a non-solvent component whieh will form with the seleetive solvent an azeotropie mixture. By using typical conditions, the process is able to reeover a pure PVC eompound powder ready for use without any additional treatment like melt filtration or a new pelletisation (speeific characteristics of the powder are average diameter of 400 microns and bulk density above 600 kg/ eub.m). All the solvents used are eompletely reeyeled and reused. PVC compounds recovered in the Vinyloop process can be reused in a closed-loop recycling scheme... 

Applications Shake-flask extraction nowadays finds only limited application in polymer/additive analysis. Carlson et al. [108] used this technique to extract antioxidants from rubber vulcanisates for identification purposes (NMR, IR, MS). Wrist-action shaking at room temperature was also used as the sample preparation step for the UV and IR determination of Ionol CP, Santonox R and oleamide extracted from pelletised polyethylene using different solvents [78]. BHT could be extracted in 98 % yield from powdered PP by shaking at room temperature for 30 min with carbon disulfide. 

Litster, J. D., and Ennis, B. J., Granulation, Pelletisation, and Particle Coating, short course given at IChemE - Australia, Gold Beach, Australia (1994)... 

If stored for too long, magnesium oxide can convert to magnesium carbonate or hydroxide with resultant loss of activity as an acid acceptor. Magnesium oxide supplied in stick form overcomes this problem. Some forms of pelletised magnesium oxides can be too hard to break down in soft compounds and problems can arise from hard undispersed ceramic -like particles. 

Many manufacturers supply extruders with interchangeable heads, which can act as strainers, roller die devices or pelletisers. 

Pelletisers are designed to convert a Banbury mixer batch into free flowing pellets which can easily be conveyed to the next step in a process. 

Summarising the literature data it can be stated that most energy consumption in crop production is used on the field in the form of fertiliser and diesel. Only those energy-intensive processes such as drying or pelletising of haulm-type... 

Bell, J.H., Fisons Patent, Pelletised medieament formulations. Application no. 152047 (1975). Vidgren, M.T., Vidgren, P.A., and Paronen, T.P., Int. J. Pharm., 35 139-144 (1987). Chawla, A., Spray-dried Powders for Use in Dry Powder Aerosol Formulation, PhD Thesis, University of London, 1993. 

Three different fuels were studied two mixtures of pelletised bark and wood, and one fuel made of pelletised straw. More data regarding the fuel used by Orlanders et al is showed in Table 4 below. 

Various forms of ancillary equipment are required, in particular to ensure consistent addition of feedstock streams to the process equipment, to undertake melt cooHng and pelletisation, and, in some instances, to filter out extraneous contaminants. 

One of the drawbacks associated especially with slurry and solution CSTR processes is the necessity of removing the solvent or diluent in a post-production step. In a gas phase reactor the polymerisation takes place in a fluidised bed of polymer particles. Inert gas or gas mixture is used for fluidisation. The gas flow is circulated through the polymer bed and a heat-ex-changer in order to remove the polymerisation heat. Gaseous ethylene and comonomer are fed into the fluidisation gas line of the reactor, and a supported catalyst is added directly to the fluidised bed (Fig. 7). Polymerisation occurs at a pressure of about 20-25 bar and a temperature of about 75-110 °C. The polymer is recovered as a solid powder which is, however, usually pelletised. Due to the limited cooling capacity of the fluidising gas, reactor... 

---