Abstract: Filter cake produced from a slurry is compressed in an enclosure (6) having a pair of opposed flexible walls (5) at least one of which is constituted by a filter and drainage medium. The filter cake is cyclically deformed while under compression with the filter cake supported at least one position (14, 52) within its periphery whereby the unsupported parts of the filter cake are cyclically deformed about the periphery and the position or positions of support. All parts of the filter cake are thus subjected to substantially uniform bending whereby drying of the filter cake is improved.

Abstract: Filter cake formed from a slurry is dried in a filter press comprising a plurality of filtration units each having a chamber bounded by a pair of opposed flexible walls with at least one of said walls being constituted by a filter medium. The flexible walls are sandwiched between flexible membranes. The filter cake is formed and compressed in the chambers by hydraulic fluid pressure acting on the flexible membranes. By means of pressure oscillations set up in the hydraulic fluid, the filter cake in the chambers is deformed by bowing from side to side of an initial central plane, whereby drying is improved.

Abstract: A process for making magnesium hydroxide which comprises treating brine with an adsorptive magnesium hydroxide whereby at least part of the boron ions contained in the brine are adsorbed on to the adsorptive magnesium hydroxide, the brine being mixed counter-currently with the adsorptive magnesium hydroxide in a series of stages such that at each stage the brine is successively contacted with adsorptive magnesium hydroxide from a succeeding stage and there is recovered from the final stage a brine of reduced boron ion content, reacting the brine of reduced boron ion content with alkali to precipitate a low boron magnesium hydroxide and recovering the low boron magnesium hydroxide.