Melt crystallization Phillips process

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One type of suspension processes using a scraped crystallizer to create the feed suspension is the Phillips process (see McKay 1967). The crystallizer consists of a vessel with filters in the wall of the upper section. There is a heater at the bottom to remelt the crystals. Some of the melt is taken as product, some is used as reflux. The reflux serves mainly as washing liquid for the crystals which are forced downward by a reciprocating piston, or with pulses from a pulsator pump. The Phillips crystallizer column is shown in Figure 7.14. 

In the Phillips process, which nowadays is applied in only few cases, the crystal-lizate is refined by counter current crystallization in a pulse column through the ascending melt (Figure 4.20) this process was introduced in 1957. 

A fourth process is the Brennan-Koppers crystal purifier (Brennan 1982). The apparatus has wall filters like the Phillips column and a melter at the top like the Kureha process. The crystals move up due to the movement of the liquid. The crystal bed is held compact with a rotating top plate, which is called a harvester. Some crystals at the top of the bed are collected (scraped off) and some openings thereafter permit these crystals to enter the melting zone at an adjustable rate. Some of the remolten liquid flows back through the harvester and washes the crystals in the bed. The residue leaves the apparatus by the filters. Details are given in the patent cited above. 

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