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An investigation was carried out into the effect of solids volume fraction and pH on the shear and compressive yield stress of fine particulate kaolin and limestone suspensions. The variation in the surface chemistry and the resulting changes in inter-particle forces and microstructure had a major effect on the rheological behaviour. This effect can be used to control the rheological properties of suspensions to optimise solid-liquid separation processes such as the dewatering of suspensions in solid bowl centrifuges., An investigation was carried out into the effect of solids volume fraction and pH on the shear and compressive yield stress of fine particulate kaolin and limestone suspensions. The variation in the surface chemistry and the resulting changes in inter-particle forces and microstructure had a major effect on the rheological behaviour. This effect can be used to control the rheological properties of suspensions to optimise solid-liquid separation processes such as the dewatering of suspensions in solid bowl centrifuges.

Laboratory and pilot-scale tests are described of the moving bed washing process. Two fractions of quartz sand were used with NaCl solution as the mother liquor and demineralised water as the wash liquid. The structure of the moving bed was analysed in relation to the local average particle velocity, the porosity in the wash chamber, the purification results and the dispersion behaviour. The results show that the level of residual impurities can be reduced by a magnitude of one to two when compared with conventional cake washing. For a given required degree of purity, the amount of wash liquid can be significantly reduced., Laboratory and pilot-scale tests are described of the moving bed washing process. Two fractions of quartz sand were used with NaCl solution as the mother liquor and demineralised water as the wash liquid. The structure of the moving bed was analysed in relation to the local average particle velocity, the porosity in the wash chamber, the purification results and the dispersion behaviour. The results show that the level of residual impurities can be reduced by a magnitude of one to two when compared with conventional cake washing. For a given required degree of purity, the amount of wash liquid can be significantly reduced.

The effects were investigated of solids concentration, pH, electrolyte type and dosage on the sedimentation behaviour of quartz and limestone suspensions. The sedimentation rate of quartz in de-ionised water decreased with increasing solids concentration. The sedimentation of coarse particles was not affected by the addition of an electrolyte (AlCl3) but fine particles tended to coagulate at higher electrolyte concentrations. At low pH values the suspension was destabilised while at alkaline pH the surface charges on the quartz were high enough to stabilise the suspension. Studies of the effect of a polymeric dispersing agent on the sedimentation behaviour of limestone particles showed that a small amount of dispersant resulted in a slightly higher sedimentation rate. Higher dosages resulted in stabilisation of the suspensions. Application of studies of the sedimentation behaviour of particles to calculate the separation efficiency of a decanter centrifuge is described using the example of a classification process for kaolin., The effects were investigated of solids concentration, pH, electrolyte type and dosage on the sedimentation behaviour of quartz and limestone suspensions. The sedimentation rate of quartz in de-ionised water decreased with increasing solids concentration. The sedimentation of coarse particles was not affected by the addition of an electrolyte (AlCl3) but fine particles tended to coagulate at higher electrolyte concentrations. At low pH values the suspension was destabilised while at alkaline pH the surface charges on the quartz were high enough to stabilise the suspension. Studies of the effect of a polymeric dispersing agent on the sedimentation behaviour of limestone particles showed that a small amount of dispersant resulted in a slightly higher sedimentation rate. Higher dosages resulted in stabilisation of the suspensions. Application of studies of the sedimentation behaviour of particles to calculate the separation efficiency of a decanter centrifuge is described using the example of a classification process for kaolin.

Cardiovascular disease (CVD) has a multifactorial aetiology and many potential risk markers are known. As it was not feasible to discuss all markers and their possible interactions in relation to all aspects of CVD, selections had to be made in this paper. In the context of claims and functional foods, emphasis was placed on those aetiological processes and risk markers that have been shown previously to be modified by diet: lipid and lipoprotein metabolism, haemostatic function, oxidative damage, homocysteine metabolism, and blood pressure. Except for methodological and biological characteristics of these biomarkers, their relationships with the risk of CVD are discussed. For LDL and HDL cholesterol, fasting triacylglycerol, homocysteine, and blood pressure well-validated, easy applicable, and generally accepted biomarkers exist. For haemostatic function and oxidative damage validation of markers with respect to CVD or intermediate clinical markers is recommended. For diet-related CVD, however, the ultimate question is whether changes in the biomarker are truly related to changes in risk. Only for LDL cholesterol and blood pressure does consensus exist among scientists for a possible application as enhanced function claims. For HDL, triacylglycerol, and homocysteine, and in particular for haemostatic function and oxidative damage, however, formal proof is lacking that diet-induced changes in these biomarkers alter the risk of CVD. At the same time, it should be emphasised that CVD is multifactorial. Therefore it does not seem justified that a change in one particular biomarker is enough evidence to substantiate a claim. There are examples of food components or drugs that one biomarker is changed in a favourable way, but at the same time another biomarker is changed in an unfavourable way. Therefore, studies to further validate generic predictors for the CVD risk should be initiated.

The residual moisture of bulk materials after conventional vibration dewatering is often only a little lower than that achievable by gravitational dewatering due to the limiting drop formation mechanism on vibrating sieves. Pilot-scale studies have shown that the use of capillary suction media can reduce residual moisture content. This is the first continuous operation in pilot scale of the system at the Institut fur Mechanische Verfahrenstechnik und Mechanik, Germany. The use of such a modified vibrating sieve for dewatering coal and quartz sands was studied., The residual moisture of bulk materials after conventional vibration dewatering is often only a little lower than that achievable by gravitational dewatering due to the limiting drop formation mechanism on vibrating sieves. Pilot-scale studies have shown that the use of capillary suction media can reduce residual moisture content. This is the first continuous operation in pilot scale of the system at the Institut fur Mechanische Verfahrenstechnik und Mechanik, Germany. The use of such a modified vibrating sieve for dewatering coal and quartz sands was studied.

Steam is used instead of pressurised air in steam pressure filtration. The process has been carried out for the first time in a continuous pressure filter using a modified hyperbar disc filter and a special steam cabin. A feldspar and a gypsum slurry produced in the flue-gas cleaning plant of a power station were processed using the method. The effects of working pressure, specific steam consumption and number of filter revolutions on dewatering were examined. It is shown that steam pressure filtration could be successfully operated in a pilot plant. Cost implications are discussed., Steam is used instead of pressurised air in steam pressure filtration. The process has been carried out for the first time in a continuous pressure filter using a modified hyperbar disc filter and a special steam cabin. A feldspar and a gypsum slurry produced in the flue-gas cleaning plant of a power station were processed using the method. The effects of working pressure, specific steam consumption and number of filter revolutions on dewatering were examined. It is shown that steam pressure filtration could be successfully operated in a pilot plant. Cost implications are discussed.

The addition of an electric field to pressure dewatering brings on the electrokinetic effects of electro-osmosis and electrophoresis and also electrolysis and a decrease in thermal viscosity. The effects of these processes are separated and discussed. Experiments on a specially constructed pressure-electro-filter showed that the acceleration of filtration kinetics is caused mainly by electrophoresis., The addition of an electric field to pressure dewatering brings on the electrokinetic effects of electro-osmosis and electrophoresis and also electrolysis and a decrease in thermal viscosity. The effects of these processes are separated and discussed. Experiments on a specially constructed pressure-electro-filter showed that the acceleration of filtration kinetics is caused mainly by electrophoresis.

Mechanical dewatering processes, especially those where pusher centrifuges are in use, can have unwanted effects such as the destruction of the separated particles which may impair product quality. A research project investigating the sources and reasons for particle destruction in solid-liquid separation apparatus, especially centrifuges, is presented., Mechanical dewatering processes, especially those where pusher centrifuges are in use, can have unwanted effects such as the destruction of the separated particles which may impair product quality. A research project investigating the sources and reasons for particle destruction in solid-liquid separation apparatus, especially centrifuges, is presented.